Development of a method for the simultaneous determination of multi-class pesticides in earthworms by liquid chromatography coupled to tandem electrospray mass spectrometry.

PubMed

Daniele, Gaëlle; Lafay, Florent; Pelosi, Céline; Fritsch, Clémentine; Vulliet, Emmanuelle

2018-06-04

Agricultural intensification, and in particular the use of pesticides, leads over the years to a loss of biodiversity and a decline of ecosystem services in cultivated zones and agricultural landscapes. Among the animal communities involved in the functioning of agro-ecosystems, earthworms are ubiquitous and recognized as indicators of land uses and cultural practices. However, little data is available on the levels of pesticides in such organisms in natura, which would allow estimating their actual exposure and the potentially resulting impacts. Thus, the objective of this study was to develop a sensitive analytical methodology to detect and quantify 27 currently used pesticides in earthworms (Allolobophora chlorotica). A modified QuEChERS extraction was implemented on individual earthworms. This step was followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The whole analytical method was validated on spiked earthworm blank samples, with regard to linearity (from 1 to 100 method limit of quantification, r 2  > 0.95), intra-day precision (relative standard deviation (RSD) < 15%), inter-day precision (RSD < 20%), recoveries (mainly in the range 70-110%), and limits of detection and of quantification (inferior to 5 ng/g for most of the pesticides). The developed method was successfully applied to determine the concentrations of pesticides in nine individuals collected in natura. Up to five of the selected pesticides have been detected in one individual. Graphical abstract.

Targeted profiling of hydrophilic constituents of royal jelly by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

PubMed

Pina, Athanasia; Begou, Olga; Kanelis, Dimitris; Gika, Helen; Kalogiannis, Stavros; Tananaki, Chrysoula; Theodoridis, Georgios; Zotou, Anastasia

2018-01-05

In the present work a Hydrophilic Interaction Liquid Chromatography-tandem Mass Spectrometry (HILIC-MS/MS) method was developed for the efficient separation and quantification of a large number of small polar bioactive molecules in Royal Jelly. The method was validated and provided satisfactory detection sensitivity for 88 components. Quantification was proven to be precise for 64 components exhibiting good linearity, recoveries R% >90% for the majority of analytes and intra- and inter-day precision from 0.14 to 20% RSD. Analysis of 125 fresh royal jelly samples of Greek origin provided useful information on royal jelly's hydrophilic bioactive components revealing lysine, ribose, proline, melezitose and glutamic acid to be in high abundance. In addition the occurrence of 18 hydrophilic nutrients which have not been reported previously as royal jelly constituents is shown. Copyright © 2017 Elsevier B.V. All rights reserved.

Qualitative and quantitative measurement of cannabinoids in cannabis using modified HPLC/DAD method.

PubMed

Patel, Bhupendra; Wene, Daniel; Fan, Zhihua Tina

2017-11-30

This study presents an accurate and high throughput method for the quantitative determination of various cannabinoids in cannabis plant material using high pressure liquid chromatography (HPLC) with a diode array detector (DAD). Sample extraction and chromatographic analysis conditions for the measurement of cannabinoids in the complex cannabis plant material matrix were optimized. The Agilent Poroshell 120 SB-C18 column provided high resolution for all target analytes with a short run time (10minutes) given the core shell technology. The aqueous buffer mobile phase was optimized with ammonium acetate at pH 4.75. The change in the mobile phase and the new column ensured a separation between cannabidiol (CBD and cannabigerol (CBG) along with cannabigerol and tetrahydrocannabinolic acid (THCA), which were not well separated by previous publications, improved buffering capacity, and provided analytical performance stability. Moreover, baseline drifting was significantly minimized by the use of a low concentration buffer solution (25mM ammonium acetate). In addition, evaporation and reconstitution of the sample residue with a methanol-organic pure (OP) water solution (65:35) significantly reduced the matrix interference. The modified extraction produced good recoveries (>91%) for each of the eight cannabinoids. The optimized method was validated for specificity, linearity, sensitivity, precision, accuracy, and stability. The combined relative standard deviation (%RSD) for intra-day and inter-day precision for all eight analytes varied from 2.5% to 5.2% and 0.28% to 5.5%, respectively. The %RSD for the repeatability study varied from 1.1% to 5.5%. The recoveries from spiked cannabis matrix samples were greater than 90% for all analytes, except delta-8-tetrahydrocannabinol (Δ 8 -THC), which was 80%. The recoveries varied from 81% to 107% with a precision of 0.7-8.1%RSD. Delta-9-tetrahydrocannabinol (Δ 9 -THC) in all of the cannabis samples (n=635) was less than 10%, which is in compliance with the NJ Medicinal Marijuana regulation. Analysis of samples from two cultivars, which included ten individual samples, four composite samples, seven calibration standards, and four quality control standards, can be performed within 24hours by this high throughput method. Published by Elsevier B.V.

Real time quantitative colourimetric test for methamphetamine detection using digital and mobile phone technology.

PubMed

Choodum, Aree; Parabun, Kaewalee; Klawach, Nantikan; Daeid, Niamh Nic; Kanatharana, Proespichaya; Wongniramaikul, Worawit

2014-02-01

The Simon presumptive color test was used in combination with the built-in digital camera on a mobile phone to detect methamphetamine. The real-time Red-Green-Blue (RGB) basic color data was obtained using an application installed on the mobile phone and the relationship profile between RGB intensity, including other calculated values, and the colourimetric product was investigated. A wide linear range (0.1-2.5mg mL(-1)) and a low detection limit (0.0110±0.0001-0.044±0.002mg mL(-1)) were achieved. The method also required a small sample size (20μL). The results obtained from the analysis of illicit methamphetamine tablets were comparable to values obtained from gas chromatograph-flame ionization detector (GC-FID) analysis. Method validation indicated good intra- and inter-day precision (2.27-4.49%RSD and 2.65-5.62%RSD, respectively). The results suggest that this is a powerful real-time mobile method with the potential to be applied in field tests. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Investigation of six bioactive anthraquinones in slimming tea by accelerated solvent extraction and high performance capillary electrophoresis with diode-array detection.

PubMed

Wang, Ning; Su, Ming; Liang, Shuxuan; Sun, Hanwen

2016-05-15

A rapid and effective method for effective separation and rapid simultaneous determination of six bioactive anthraquinones by capillary zone electrophoresis was developed. An accelerated solvent extraction procedure was used for the extraction of anthraquinones from slimming tea. Under the optimized conditions, the effective separation of six anthraquinones was achieved within 8 min. Good linearity was achieved, with a correlation coefficient (r) of ⩾ 0.999. The limit of detection ranged from 0.33 to 1.40 μg mL(-1). The intra- and inter-day relative standard deviation (RSD) of the six analytes was in the range of 2.3-3.9% and 3.2-4.9%, respectively. The average recovery of the six analytes from real tea samples was in the range of 86.15-98.30% with the RSD of 1.04-4.99%. The developed and validated method has speediness, high sensitivity, recovery and precision, and can be applied for the quality control of slimming tea. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multivariate optimization and validation of an analytical methodology by RP-HPLC for the determination of losartan potassium in capsules.

PubMed

Bonfilio, Rudy; Tarley, César Ricardo Teixeira; Pereira, Gislaine Ribeiro; Salgado, Hérida Regina Nunes; de Araújo, Magali Benjamim

2009-11-15

This paper describes the optimization and validation of an analytical methodology for the determination of losartan potassium in capsules by HPLC using 2(5-1) fractional factorial and Doehlert designs. This multivariate approach allows a considerable improvement in chromatographic performance using fewer experiments, without additional cost for columns or other equipment. The HPLC method utilized potassium phosphate buffer (pH 6.2; 58 mmol L(-1))-acetonitrile (65:35, v/v) as the mobile phase, pumped at a flow rate of 1.0 mL min(-1). An octylsilane column (100 mm x 4.6mm i.d., 5 microm) maintained at 35 degrees C was used as the stationary phase. UV detection was performed at 254 nm. The method was validated according to the ICH guidelines, showing accuracy, precision (intra-day relative standard deviation (R.S.D.) and inter-day R.S.D values <2.0%), selectivity, robustness and linearity (r=0.9998) over a concentration range from 30 to 70 mg L(-1) of losartan potassium. The limits of detection and quantification were 0.114 and 0.420 mg L(-1), respectively. The validated method may be used to quantify losartan potassium in capsules and to determine the stability of this drug.

Determination of benzimidazole anthelmintics in milk and honey by monolithic fiber-based solid-phase microextraction combined with high-performance liquid chromatography-diode array detection.

PubMed

Zhang, Yong; Huang, Xiaojia; Yuan, Dongxing

2015-01-01

A porous poly(methacrylic acid-co-ethylene dimethacrylate) monolithic fiber (MEMF) for solid-phase microextraction (SPME) of five benzimidazole anthelmintics was prepared by in-situ polymerization. The effect of polymerization conditions on SPME of the target analytes was studied thoroughly. The physicochemical properties of the monolith were characterized by infrared spectroscopy, elemental analysis, scanning electron microscopy, and mercury intrusion porosimetry. Several conditions affecting the extraction efficiency were investigated and, under the optimized conditions, a simple and sensitive method for the determination of trace benzimidazoles residues in milk and honey was established by coupling MEMF-SPME with high-performance liquid chromatography-diode array detection (MEMF-SPME-HPLC-DAD). Under the optimum experimental conditions, the limits of detection (S/N = 3) of the method were 0.11-0.30 μg L(-1) for milk and 0.086-0.28 μg L(-1) for honey. Evaluation of intra-day and inter-day precision showed reproducibility was satisfactory-relative standard deviations (RSD) for both were <10 %. Finally, the method was successfully used for determination of benzimidazole residues in milk and honey. Recoveries obtained for determination of benzimidazole anthelmintics in spiked samples ranged from 72.3 to 121 %, with RSD always <11 %.

Towards the identification of alkaline phosphatase binding ligands in Li-Dan-Hua-Shi pills: A Box-Behnken design optimized affinity selection approach tandem with UHPLC-Q-TOF/MS analysis.

PubMed

Tao, Yi; Huang, Surun; Gu, Xianghui; Li, Weidong; Cai, Baochang

2018-05-30

Alkaline phosphatase conjugated magnetic microspheres were synthesized via amide reaction, and employed as an effective adsorbent in affinity selection of binding ligands followed by UHPLC-Q-TOF/MS analysis. The analytical validity of the developed approach was evaluated under optimized conditions and the following figures of merit were obtained: linearity, 0.01-0.5 g L -1 with good determination coefficients (R 2  = 0.9992); limits of detection (LODs), 0.003 g L -1 ; and limits of quantitation (LOQ), 0.01 g L -1 . The precision (RSD%) of the proposed affinity selection approach was studied based on intra-day (0.8%) and inter-day (1.3%) precisions. Finally, the adsorbent was successfully applied to identification of binding ligands in Li-Dan-Hua-Shi pills and good recoveries were obtained in the range from 96.9 to 99.4% (RSDs 1.6-3.0%). Copyright © 2018 Elsevier B.V. All rights reserved.

Development and validation of a stability-indicating RP-HPLC-FLD method for determination of 5-[(4-chlorophenoxy) methyl]-1, 3, 4-oxadiazole-2-thiol; A novel drug candidate.

PubMed

Shehzadi, Naureen; Hussain, Khalid; Islam, Muhammad; Bukhari, Nadeem Irfan; Asif, Noman; Khan, Muhammad Tanveer; Salman, Muhammad; Qamar, Shaista; Parveen, Sajida; Zahid, Fakhra; Shah, Arshad Ali; Bilal, Abida; Abbasi, Muhammad Athar; Siddiqui, Sabahat Zahra; Rehman, Azizur

2018-03-01

The present study describes the development and validation of a simple high performance liquid chromatographic method for the determination of a novel drug candidate, 5-[(4-chlorophenoxy) methyl]-1, 3, 4-oxadiazole-2-thiol. The stability-indicating capacity of the method was evaluated by subjecting the compound's solution to hydrolytic, oxidative, photolytic, transition metal- and thermal- stress. The chromatographic separation was achieved over a C18 column (Promosil, 5 µm, 4.60 × 250 mm), maintained at 25°C, using an isocratic mobile phase comprising a mixture of acetonitrile and acidified water of pH 2.67 (1:1, v/v), at a flow rate of 1.00 mL/min and detection using a fluorescent light detector (excitation at 250 nm and emission at 410 nm). The Beer's law was followed over the concentration range 2.50-50.00 μg/ml. The recovery (98.56-100.19%, SD <5%), intraday accuracy and precision (97.31-100.81%, RSD <5%), inter-day accuracy and precision (97.50-100.75%, RSD <5%) and intermediate accuracy and precision (98.10-99.91%, RSD <5%) indicated that the method was reliable, repeatable, reproducible and rugged. The resolution and selectivity factors of the compound's peak from the nearest resolving peak, particularly in case of dry heat and copper metal stress, were found to be greater than 2 and 1, respectively, which indicated specificity and selectivity. The compound was extensively decomposed in alkaline-hydrolytic, oxidative, metal- and dry heat- stress. However, the compound in acidic and neutral conditions was resistant to photolysis. The results of the present study indicate that the developed method is specific, selective, sensitive and suitable, hence, may be used for quality control, stability testing and preformulation studies.

Gas chromatographic analysis of fatty acid methyl esters of milk fat by an ionic liquid derived from L-phenylalanine as the stationary phase.

PubMed

Mendoza, Laura González; González-Álvarez, Jaime; Gonzalo, Carla Fernández; Arias-Abrodo, Pilar; Altava, Belén; Luis, Santiago V; Burguete, Maria Isabel; Gutiérrez-Álvarez, María Dolores

2015-10-01

A Gas Chromatography (GC) method has been developed for the separation and characterization of the different fatty acids in anhydrous milk fat (AMF) by means of an ionic liquid stationary phase, characterized by a monocationic imidazolium salt derived from L-phenylalanine. The inner surface of a fused silica capillary column was modified using this ionic liquid functionality and 3-aminopropyldiethoxymethyl silane. This coated GC column, which exhibited good thermal stability (270°C) and good efficiency (2700 plates/m), has been characterized using the Abraham solvation parameter model. The intra-day and inter-day precision of the method have been evaluated, obtaining relative standard deviations (RSD) from 0.99% to 4.0% and from 2.8% to 9.2%, respectively. Furthermore, recoveries from 90% and 99% have been achieved. Copyright © 2015 Elsevier B.V. All rights reserved.

Magnetic N-doped carbon nanotubes: A versatile and efficient material for the determination of polycyclic aromatic hydrocarbons in environmental water samples.

PubMed

Menezes, Helvécio Costa; de Barcelos, Stella Maris Resende; Macedo, Damiana Freire Dias; Purceno, Aluir Dias; Machado, Bruno Fernades; Teixeira, Ana Paula Carvalho; Lago, Rochel Monteiro; Serp, Philippe; Cardeal, Zenilda Lourdes

2015-05-11

This paper describes a new, efficient and versatile method for the sampling and preconcentration of PAH in environmental water matrices using special hybrid magnetic carbon nanotubes. These N-doped amphiphilic CNT can be easily dispersed in any aqueous matrix due to the N containing hydrophilic part and at the same time show high efficiency for the adsorption of different PAH contaminants due to the very hydrophobic surface. After adsorption, the CNT can be easily removed from the medium by a simple magnetic separation. GC/MS analyses showed that the CNT method is more efficient than the use of polydimethylsiloxane (PDMS) with much lower solvent consumption, technical simplicity and time, showing good linearity (range 0.18-80.00 μg L(-1)) and determination coefficient (R(2) > 0.9810). The limit of detection ranged from 0.05 to 0.42 μg L(-1) with limit of quantification from 0.18 to 1.40 μg L(-1). Recovery (n=9) ranged from 80.50 ± 10 to 105.40 ± 12%. Intraday precision (RSD, n=9) ranged from 1.91 to 9.01%, whereas inter day precision (RSD, n=9) ranged from 7.02 to 17.94%. The method was applied to the analyses of PAH in four lake water samples collected in Belo Horizonte City, Brazil. Copyright © 2015 Elsevier B.V. All rights reserved.

[Determination of tungsten and cobalt in the air of workplace by ICP-OES].

PubMed

Zhang, J; Ding, C G; Li, H B; Song, S; Yan, H F

2017-08-20

Objective: To establish the inductively coupled plasma optical emission spectrometry (ICP-OES) method for determination of cobalt and tungsten in the air of workplace. Methods: The cobalt and tungsten were collected by filter membrane and then digested by nitric acid, inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the detection of cobalt and tungsten. Results: The linearity of tungsten was good at the range of 0.01-1 000 μg/ml with a correlation coefficient of 0.999 9, the LOD and LOQ were 0.006 7 μg/ml and 0.022 μg/ml, respectively. The recovery was ranged from 98%-101%, the RSD of intra-and inter-batch precision were 1.1%-3.0% and 2.1%-3.8%, respectively. The linearity of cobalt was good at the range of 0.01-100 μg/ml with a correlation coefficient of 0.999 9, the LOD and LOQ were 0.001 2 μg/ml and 0.044 μg/ml, respectively. The recovery was ranged from 95%-97%, the RSD of intra-and inter-batch precision were 1.1%-2.4% and 1.1%-2.9%, respectively. The sampling efficiency of tungsten and cobalt were higher than 94%. Conclusion: The linear range, sensitivity and precision of the method was suitable for the detection of tungsten and cobalt in the air of workplace.

Development, validation and evaluation of an analytical method for the determination of monomeric and oligomeric procyanidins in apple extracts.

PubMed

Hollands, Wendy J; Voorspoels, Stefan; Jacobs, Griet; Aaby, Kjersti; Meisland, Ane; Garcia-Villalba, Rocio; Tomas-Barberan, Francisco; Piskula, Mariusz K; Mawson, Deborah; Vovk, Irena; Needs, Paul W; Kroon, Paul A

2017-04-28

There is a lack of data for individual oligomeric procyanidins in apples and apple extracts. Our aim was to develop, validate and evaluate an analytical method for the separation, identification and quantification of monomeric and oligomeric flavanols in apple extracts. To achieve this, we prepared two types of flavanol extracts from freeze-dried apples; one was an epicatechin-rich extract containing ∼30% (w/w) monomeric (-)-epicatechin which also contained oligomeric procyanidins (Extract A), the second was an oligomeric procyanidin-rich extract depleted of epicatechin (Extract B). The parameters considered for method optimisation were HPLC columns and conditions, sample heating, mass of extract and dilution volumes. The performance characteristics considered for method validation included standard linearity, method sensitivity, precision and trueness. Eight laboratories participated in the method evaluation. Chromatographic separation of the analytes was best achieved utilizing a Hilic column with a binary mobile phase consisting of acidic acetonitrile and acidic aqueous methanol. The final method showed linearity for epicatechin in the range 5-100μg/mL with a correlation co-efficient >0.999. Intra-day and inter-day precision of the analytes ranged from 2 to 6% and 2 to 13% respectively. Up to dp3, trueness of the method was >95% but decreased with increasing dp. Within laboratory precision showed RSD values <5 and 10% for monomers and oligomers, respectively. Between laboratory precision was 4 and 15% (Extract A) and 7 and 30% (Extract B) for monomers and oligomers, respectively. An analytical method for the separation, identification and quantification of procyanidins in an apple extract was developed, validated and assessed. The results of the inter-laboratory evaluation indicate that the method is reliable and reproducible. Copyright © 2017. Published by Elsevier B.V.

Development and Validation of an HPLC Method for Karanjin in Pongamia pinnata linn. Leaves.

PubMed

Katekhaye, S; Kale, M S; Laddha, K S

2012-01-01

A rapid, simple and specific reversed-phase HPLC method has been developed for analysis of karanjin in Pongamia pinnata Linn. leaves. HPLC analysis was performed on a C(18) column using an 85:13.5:1.5 (v/v) mixtures of methanol, water and acetic acid as isocratic mobile phase at a flow rate of 1 ml/min. UV detection was at 300 nm. The method was validated for accuracy, precision, linearity, specificity. Validation revealed the method is specific, accurate, precise, reliable and reproducible. Good linear correlation coefficients (r(2)>0.997) were obtained for calibration plots in the ranges tested. Limit of detection was 4.35 μg and limit of quantification was 16.56 μg. Intra and inter-day RSD of retention times and peak areas was less than 1.24% and recovery was between 95.05 and 101.05%. The established HPLC method is appropriate enabling efficient quantitative analysis of karanjin in Pongamia pinnata leaves.

Development and Validation of an HPLC Method for Karanjin in Pongamia pinnata linn. Leaves

PubMed Central

Katekhaye, S; Kale, M. S.; Laddha, K. S.

2012-01-01

A rapid, simple and specific reversed-phase HPLC method has been developed for analysis of karanjin in Pongamia pinnata Linn. leaves. HPLC analysis was performed on a C18 column using an 85:13.5:1.5 (v/v) mixtures of methanol, water and acetic acid as isocratic mobile phase at a flow rate of 1 ml/min. UV detection was at 300 nm. The method was validated for accuracy, precision, linearity, specificity. Validation revealed the method is specific, accurate, precise, reliable and reproducible. Good linear correlation coefficients (r2>0.997) were obtained for calibration plots in the ranges tested. Limit of detection was 4.35 μg and limit of quantification was 16.56 μg. Intra and inter-day RSD of retention times and peak areas was less than 1.24% and recovery was between 95.05 and 101.05%. The established HPLC method is appropriate enabling efficient quantitative analysis of karanjin in Pongamia pinnata leaves. PMID:23204626

Environmentally friendly ionic liquid-in-water microemulsions for extraction of hydrophilic and lipophilic components from Flos Chrysanthemi.

PubMed

Chen, Jue; Cao, Jun; Gao, Wen; Qi, Lian-Wen; Li, Ping

2013-10-21

Ionic liquids (ILs) have numerous chemical applications as environmentally green solvents that are extending into microemulsion applications. In this work, a novel benign IL-in-water microemulsion system modified by an IL surfactant has been proposed for simultaneous extraction of hydrophilic and lipophilic constituents from Flos Chrysanthemi (Chrysanthemum morifolium). Constituents were analyzed by rapid-resolution liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. A mixture-design approach was used to optimize the IL surfactant and the IL oil phase in the microemulsion system. Microemulsions consisting of 6.0% 1-dodecyl-3-methylimidazolium hydrogen sulfate, 0.1% 1-vinyl-3-methylimidazolium hexafluorophosphate and 93.9% water offered the acceptable extract efficiency that are comparable to or even better than conventional volatile organic solvents. This assay was fully validated with respect to the linearity of response (r(2) > 0.999 over two orders of magnitude), precision (intra-RSD < 0.49 and inter-day RSD < 2.21), and accuracy (recoveries ranging from 93.73% to 101.84%). The proposed IL-in-water microemulsion method provided an environmentally friendly alternative for efficient extraction of compounds from Flos Chrysanthemi and could be extended to complex environmental and pharmaceutical samples.

Deep Eutectic Solvent-Based Microwave-Assisted Method for Extraction of Hydrophilic and Hydrophobic Components from Radix Salviae miltiorrhizae.

PubMed

Chen, Jue; Liu, Mengjun; Wang, Qi; Du, Huizhi; Zhang, Liwei

2016-10-17

Deep eutectic solvents (DESs) have attracted significant attention as a promising green media. In this work, twenty-five kinds of benign choline chloride-based DESs with microwave-assisted methods were applied to quickly extract active components from Radix Salviae miltiorrhizae . The extraction factors, including temperature, time, power of microwave, and solid/liquid ratio, were investigated systematically by response surface methodology. The hydrophilic and hydrophobic ingredients were extracted simultaneously under the optimized conditions: 20 vol% of water in choline chloride/1,2-propanediol (1:1, molar ratio) as solvent, microwave power of 800 W, temperature at 70 °C, time at 11.11 min, and solid/liquid ratio of 0.007 g·mL -1 . The extraction yield was comparable to, or even better than, conventional methods with organic solvents. The microstructure alteration of samples before and after extraction was also investigated. The method validation was tested as the linearity of analytes ( r ² > 0.9997 over two orders of magnitude), precision (intra-day relative standard deviation (RSD) < 2.49 and inter-day RSD < 2.96), and accuracy (recoveries ranging from 95.04% to 99.93%). The proposed DESs combined with the microwave-assisted method provided a prominent advantage for fast and efficient extraction of active components, and DESs could be extended as solvents to extract and analyze complex environmental and pharmaceutical samples.

Simultaneous determination of eight active components in Houttuynia cordata injection and its quality control in productive process.

PubMed

Ji, Wei; Bi, Kaishun; Chen, Qianqian; Jiang, Lingyan; Liang, Ke; Li, Qing

2011-11-01

A simple, reliable and effective gas chromatography coupled with flame ionization detection method was developed for the simultaneous determination of eight components (α-pinene, β-pinene, myrcene, limonene, terpinen-4-ol, α-terpineol, bornyl acetate and methyl-n-nonylketone) in Chinese medicine Houttuynia cordata and its injection. The chromatographic separation of all eight components, including undecylene as internal standard was performed on a DB-1 column (30 m×0.25 mm, 0.25 μm). Excellent linear behaviors including herb and injection over the investigated concentration ranges were observed with the values of r(2) higher than 0.9990 for all analytes. Satisfactory intra-day and inter-day precisions were achieved with RSD less than 2% and the average recoveries for all analytes at three different concentrations obtained were in the range of 93.4-104.4%, with RSD ranging from 1.3 to 4.1%. The proposed method was successfully applied in the simultaneous determination of these active components in H. cordata and H. cordata injection (HCI), including the intermediate product of HCI in productive process, from different pharmaceutical factories and different production batches, indicating that the method in this paper was particularly suitable for the routine analysis of HCI and its quality control in productive process. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of d-limonene in adipose tissue by gas chromatography-mass spectrometry

PubMed Central

Miller, Jessica A.; Hakim, Iman A.; Thomson, Cynthia; Thompson, Patricia; Chow, H-H. Sherry

2008-01-01

We developed a novel method for analyzing d-limonene levels in adipose tissue. Fat samples were subjected to saponification followed by solvent extraction. d-Limonene in the sample extract was analyzed using gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring. Linear calibration curves were established over the mass range of 79.0-2,529 ng d-limonene per 0.1 grams of adipose tissue. Satisfactory within day precision (RSD 6.7 to 9.6%) and accuracy (% difference of −2.7 to 3.8%) and between day precision (RSD 6.0 to 10.7%) and accuracy (% difference of 1.8 to 2.6%) were achieved. The assay was successfully applied to human fat biopsy samples from a d-limonene feeding trial. PMID:18571481

An LC-MS/MS method for simultaneous determination of nine steroidal saponins from Paris polyphylla var. in rat plasma and its application to pharmacokinetic study.

PubMed

Yang, Guangyi; Lu, Wei; Pan, Meng; Zhang, Chenning; Zhou, Yuan; Hu, Pei; Hu, Ming; Song, Gao

2017-10-25

Paris polyphylla var is an herbal plant herb widely used in Traditional Chinese Medicine. The purpose of this study is to develop an Ultra Performance Liquid Chromatography-tandem mass spectrometer (UPLC-MS) method to quantify the major components (i.e., nine saponins) from P. polyphylla in plasma samples. A UItra BiPh column (100×2.1mm, 5μm) was used with acetonitrile/0.1% formic acid in water as mobile phases. The analytes were quantified using a Waters XEVO TQ mass spectrometer via multiple reaction monitoring (MRM) with positive scan mode. A protein precipitation method was used to extract the analytes from rat plasma. The inter/intra-day precision, accuracy, recovery, matrix effect, and stability were evaluated per the FDA guidance. The method showed linearity in the concentration ranges of 2.4-1250ng/mL. The intra-day and inter-day precisions (RSD) of these analytes at three different levels were less than 15.0%. The extraction recoveries of these analytes were from 83.8% to 109.4% and the matrix effects ranged from 87.4% to 105.4%. The stabilities of these compounds in plasma were evaluated by analyzing three different concentrations following storage at 25°C for 6h, and -80°C for 30days. All the samples displayed less than 15.0% variations. The validated method was successfully used to a pharmacokinetic (PK) study using Sprague Dawley (SD) rats with intravenous (i.v.) and oral (p.o.) administration of P. polyphylla extract. The applications revealed that this method can be used to analyze major steroidal saponins from P. polyphylla in biological samples. Copyright © 2017 Elsevier B.V. All rights reserved.

High-throughput quantitation of amino acids in rat and mouse biological matrices using stable isotope labeling and UPLC-MS/MS analysis.

PubMed

Takach, Edward; O'Shea, Thomas; Liu, Hanlan

2014-08-01

Quantifying amino acids in biological matrices is typically performed using liquid chromatography (LC) coupled with fluorescent detection (FLD), requiring both derivatization and complete baseline separation of all amino acids. Due to its high specificity and sensitivity, the use of UPLC-MS/MS eliminates the derivatization step and allows for overlapping amino acid retention times thereby shortening the analysis time. Furthermore, combining UPLC-MS/MS with stable isotope labeling (e.g., isobaric tag for relative and absolute quantitation, i.e., iTRAQ) of amino acids enables quantitation while maintaining sensitivity, selectivity and speed of analysis. In this study, we report combining UPLC-MS/MS analysis with iTRAQ labeling of amino acids resulting in the elution and quantitation of 44 amino acids within 5 min demonstrating the speed and convenience of this assay over established approaches. This chromatographic analysis time represented a 5-fold improvement over the conventional HPLC-MS/MS method developed in our laboratory. In addition, the UPLC-MS/MS method demonstrated improvements in both specificity and sensitivity without loss of precision. In comparing UPLC-MS/MS and HPLC-MS/MS results of 32 detected amino acids, only 2 amino acids exhibited imprecision (RSD) >15% using UPLC-MS/MS, while 9 amino acids exhibited RSD >15% using HPLC-MS/MS. Evaluating intra- and inter-assay precision over 3 days, the quantitation range for 32 detected amino acids in rat plasma was 0.90-497 μM, with overall mean intra-day precision of less than 15% and mean inter-day precision of 12%. This UPLC-MS/MS assay was successfully implemented for the quantitative analysis of amino acids in rat and mouse plasma, along with mouse urine and tissue samples, resulting in the following concentration ranges: 0.98-431 μM in mouse plasma for 32 detected amino acids; 0.62-443 μM in rat plasma for 32 detected amino acids; 0.44-8590μM in mouse liver for 33 detected amino acids; 0.61-1241 μM in mouse kidney for 37 detected amino acids; and 1.39-1,681 μM in rat urine for 34 detected amino acids. The utility of the assay was further demonstrated by measuring and comparing plasma amino acid levels between pre-diabetic Zucker diabetic fatty rats (ZDF/Gmi fa/fa) and their lean littermates (ZDF/Gmi fa/?). Significant differences (P<0.001) in 9 amino acid concentrations were observed, with the majority ranging from a 2- to 5-fold increase in pre-diabetic ZDF rats on comparison with ZDF lean rats, consistent with previous literature reports. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of molindone enantiomers in human plasma by high-performance liquid chromatography-tandem mass spectrometry using macrocyclic antibiotic chiral stationary phases.

PubMed

Jiang, Hongliang; Li, Yinghe; Pelzer, Mary; Cannon, Michelle J; Randlett, Christopher; Junga, Heiko; Jiang, Xiangyu; Ji, Qin C

2008-05-30

A sensitive and selective bioanalytical assay was developed and validated for the determination of enantiomeric molindone in human plasma using high-performance liquid chromatography-tandem mass spectrometry along with supported liquid extraction procedures. The chiral separation was evaluated and optimized on macrocyclic antibiotic type chiral stationary phases (CSPs) based on teicoplanin aglycone (Chirobiotic TAG) in polar organic, polar ionic, and reversed-phase mode chromatography, respectively. Complete baseline separation was achieved on a Chirobiotic TAG column under isocratic condition in reversed-phase chromatography. The method validation was conducted using a Chirobiotic TAG column (100 mm x 2.1 mm) over the curve range 0.100-100 ng/ml for each molindone enantiomer using 0.0500 ml of plasma sample. The flow rate was 0.8 ml/min and the total run time was 9 min. Supported liquid extraction in a 96-well plate format was used for sample preparation. Parameters including recovery, matrix effect, linearity, sensitivity, specificity, carryover, precision, accuracy, dilution integrity, and stability were evaluated. The intra- and inter-day precision and accuracy of the quality control samples at low, medium, and high concentration levels were RSD

Development and validation of a single LC-MS/MS assay following SPE for simultaneous hair analysis of amphetamines, opiates, cocaine and metabolites.

PubMed

Imbert, L; Dulaurent, S; Mercerolle, M; Morichon, J; Lachâtre, G; Gaulier, J-M

2014-01-01

The two major challenges in hair analysis are the limited amount of samples usually available and the low targeted concentrations. To overcome these limitations, a liquid chromatography-electrospray-tandem mass spectrometry method (LC-ESI-MS/MS) allowing the simultaneous analysis of 17 amphetamines (amphetamine, BDB, m-CPP, dexfenfluramine, DOB, DOM, ephedrine, MBDB, MDA, MDEA, MDMA, methamphetamine, methylphenidate, 4-MTA, norephedrine, norfenfluramine and PMA), 5 opiates (morphine, codeine, heroin, ethylmorphine, and 6AM), cocaine and 5 metabolites [ecgonine methyl ester (EME), benzoylecgonine (BZE), anhydroecgonine methyl ester (AME), cocaethylene, and norcocaine] has been developed. The validation procedure included linearity, intra-day and inter-day variability and accuracy for 5 days (5 replicates at 3 concentration levels). Proficiency studies were used to check the accuracy of the method. As a result, all amphetamines, opiates and cocaine derivatives were satisfactory identified by 2 MRM transitions in 15 min. Calibration curves were performed by a quadratic 1/X weighted regression. The calibration model fits from 0.05 to 10 ng/mg. The limits of detection (LODs) range between 0.005 and 0.030 ng/mg. Precision has been checked by intra-day and inter-day RSD, and associated relative bias, which were lower than 25% for the limits of quantifications (LOQs) and lower than 20% for the other levels tested. This method was routinely applied to hair samples: two positive results of adult drug addicts are presented. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

A validated high-performance liquid chromatography method with diode array detection for simultaneous determination of nine flavonoids in Senecio cannabifolius Less.

PubMed

Niu, Tian-Zeng; Zhang, Yu-Wei; Bao, Yong-Li; Wu, Yin; Yu, Chun-Lei; Sun, Lu-Guo; Yi, Jing-Wen; Huang, Yan-Xin; Li, Yu-Xin

2013-03-25

A reversed phase high performance liquid chromatography method coupled with a diode array detector (HPLC-DAD) was developed for the first time for the simultaneous determination of 9 flavonoids in Senecio cannabifolius, a traditional Chinese medicinal herb. Agilent Zorbax SB-C18 column was used at room temperature and the mobile phase was a mixture of acetonitrile and 0.5% formic acid (v/v) in water in the gradient elution mode at a flow-rate of 1.0mlmin(-1), detected at 360nm. Validation of this method was performed to verify the linearity, precision, limits of detection and quantification, intra- and inter-day variabilities, reproducibility and recovery. The calibration curves showed good linearities (R(2)>0.9995) within the test ranges. The relative standard deviation (RSD) of the method was less than 3.0% for intra- and inter-day assays. The samples were stable for at least 96h, and the average recoveries were between 90.6% and 102.5%. High sensitivity was demonstrated with detection limits of 0.028-0.085μg/ml for flavonoids. The newly established HPLC method represents a powerful technique for the quality assurance of S. cannabifolius. Copyright © 2012 Elsevier B.V. All rights reserved.

[Determination of doping in human urine by gas chromatography-high resolution mass spectrometry].

PubMed

Xing, Yan-Yi; Liu, Xin; Zhang, Yu-Mei; Wang, Xiao-Bing; Xu, You-Xuan

2012-12-01

A method was evaluated for determination of twenty-one doping (including nandrolone, boldenone and methandienone) in human urine by gas chromatography-high resolution mass spectrometry. Samples were prepared by liquid-liquid extraction, concentrated, TMS derivatization and limit of detection at ng x mL(-1) by MID/GC/HRMS. According to the code of the World Anti-Doping Agency (WADA), precision and recoveries of the procedure were evaluated by replicate analysis (n = 6), the recoveries in the range of 66%-103%, with the RSD below 10.0%. The precision within the day of the method with three different concentrations was also determined RSD were less than 9.5%, 10.0% and 9.7%.

Identification and simultaneous quantification of five alkaloids in Piper longum L. by HPLC-ESI-MS(n) and UFLC-ESI-MS/MS and their application to Piper nigrum L.

PubMed

Liu, Hao-Long; Luo, Rong; Chen, Xiao-Qing; Ba, Yin-Ying; Zheng, Li; Guo, Wei-Wei; Wu, Xia

2015-06-15

A simple, effective and suitable UFLC-ESI-MS/MS method was firstly developed to simultaneously determine five characteristic constituents (piperine, piperlonguminine, Δα,β-dihydropiperlonguminine, pellitorine and piperanine) of Piper longum L. The total alkaloids of P. longum L. was prepared. The alkaloid contents of Piper nigrum L. and P. longum L. were compared. The analysis was carried out in multiple reaction monitoring scan mode. The method showed a good specificity, linearity (R(2)>0.995), stability (RSD<2.53%), repeatability (RSD<2.58%), and recovery (90.0-103.5%). The limits of detection and limits of quantification of five alkaloids were in the range of 0.02-0.03 and 0.05-0.10 ng/mL, respectively. The intra- and inter-day precision was less than 9.30% and 9.55%, respectively. The validation results confirmed that the method could simultaneously determine the target alkaloids in the sample. Furthermore, the identities of the alkaloids were verified by HPLC-ESI-MS/MS. Compared with P. nigrum, P. longum had lower piperine content but was enriched in the other four alkaloids. Copyright © 2015 Elsevier Ltd. All rights reserved.

A critical evaluation of liquid chromatography with hybrid linear ion trap-Orbitrap mass spectrometry for the determination of acidic contaminants in wastewater effluents.

PubMed

Cahill, Michael G; Dineen, Brian A; Stack, Mary A; James, Kevin J

2012-12-28

Acidic pesticide and pharmaceutical contaminants were pre-concentrated and extracted from wastewater samples (500 mL) using solid-phase extraction. Analyte recoveries were 79-96%, with % RSD values in the range, 1.7-7.4%. Analyte identification and quantification were carried out using liquid chromatography-mass spectrometry (LC-MS) with hybrid linear ion trap (LIT) Orbitrap instrumentation. Using a resolution setting of 30,000 FWHM, full-scan MS analysis was performed using heated electrospray ionization (HESI) in negative mode. The high mass resolution capabilities of the Orbitrap MS were exploited for the determination of trace contaminants allowing facile discrimination between analytes and matrix. The dependant scan functions of the Orbitrap MS using higher collisional dissociation (HCD) and LIT MS were evaluated for the confirmation of analytes at trace concentration levels. Mass accuracy for target contaminants using this method was less than 2 ppm. The limits of quantitation (LOQs) were in the range, 2.1-27 ng/L. The inter-day accuracy and precision were measured over a five-day period at two concentrations. The % relative errors were in the range, 0.30-7.7%, and the % RSD values were in the range, 1.5-5.5%. Using this method, 2,4-D, mecoprop, ibuprofen, naproxene and gemfibrozil were identified in several wastewater treatment plants in Ireland. Copyright © 2012 Elsevier B.V. All rights reserved.

Development and validation of a HPLC-UV-ESI-MS method for the simultaneous quantitation of ten bioactive compounds in Dahuang Fuzi Tang.

PubMed

Guo, Hui; Li, Huan; Liu, Xiao; Cai, Hao; Wu, Li; Cai, Bao-Chang

2014-12-01

To develop a high performance liquid chromatography (HPLC) coupled with electrospray ionization mass spectrometry (ESI-MS) and ultraviolet (UV) detector method for the acid-alkaline simultaneous determination of ten bioactive compounds, and analyze the effect of compatible medicinal plants on the concentration of components in Dahuang Fuzi Tang (DFT). The chromatographic separation was performed on a Hypersil BDS C18 analytical column by gradient elution with acetonitrile and formate buffer (containing 0.15% formic acid, V/V) at 25 °C with a flow rate of 1.0 mL·min(-1) and UV detection at 280 nm. Four of the ten compounds in DFT were identified and their MS fragments were elucidated by HPLC-ESI-MS, and the contents of the six compounds were determined by HPLC-UV. All calibration curves showed good linear regression (r(2) ≥ 0.9990). The limits of detection and limits of quantification were 0.021-0.155 -g·mL(-1) and 0.076-0.520 -g·mL(-1), respectively. Overall precision RSD (intra-day and inter-day) were less than 2.96%, and the average recoveries were 98.35%-101.45%, with RSD ranging from 1.54% to 3.01% for the analytes. The developed method can be applied for the quality control and provide analytical evidence on the chemical basis and combinational principles of DFT. Copyright © 2014 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

Rapid liquid chromatography-tandem mass spectrometry analysis of 4-hydroxynonenal for the assessment of oxidative degradation and safety of vegetable oils.

PubMed

Gabbanini, Simone; Matera, Riccardo; Valvassori, Alice; Valgimigli, Luca

2015-04-15

A novel method for the UHPLC-MS/MS analysis of (E)-4-hydroxynonenal (4-HNE) is described. The method is based on derivatization of 4-HNE with pentafluorophenylhydrazine (1) or 4-trifluoromethylphenylhydrazine (2) in acetonitrile in the presence of trifluoroacetic acid as catalyst at room temperature and allows complete analysis of one sample of vegetable oil in only 21 min, including sample preparation and chromatography. The method involving hydrazine 1, implemented in an ion trap instrument with analysis of the transition m/z 337→154 showed LOD=10.9 nM, average accuracy of 101% and precision ranging 2.5-4.0% RSD intra-day (2.7-4.1% RSD inter-day), with 4-HNE standard solutions. Average recovery from lipid matrices was 96.3% from vaseline oil, 91.3% from sweet almond oil and 105.3% from olive oil. The method was tested on the assessment of safety and oxidative degradation of seven samples of dietary oil (soybean, mixed seeds, corn, peanut, sunflower, olive) and six cosmetic-grade oils (avocado, blackcurrant, apricot kernel, echium, sesame, wheat germ) and effectively detected increased 4-HNE levels in response to chemical (Fenton reaction), photochemical, or thermal stress and aging, aimed at mimicking typical oxidation associated with storage or industrial processing. The method is a convenient, cost-effective and reliable tool to assess quality and safety of vegetable oils. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous determination of gingerols and shogaol using capillary liquid chromatography and its application in discrimination of three ginger varieties from Indonesia.

PubMed

Rafi, Mohamad; Lim, Lee Wah; Takeuchi, Toyohide; Darusman, Latifah Kosim

2013-01-15

A new method using reversed phase capillary liquid chromatography was developed for simultaneous determination of four bioactive compounds found in ginger (Zingiber officinale) namely, 6-, 8-, 10-gingerol, and 6-shogaol. The separation of these four compounds was performed using C30 as the stationary phase and 60% acetonitrile as the mobile phase in isocratic elution mode with a flow rate of 5 μL/min. All four compounds were separated within 25 min with good resolution. As the evaluation of method validation, a linear regression of the four compounds was obtained within the tested range with correlation coefficients ≥ 0.9995. The limits of detection and quantitation were between 0.034-0.039 μg/mL and 0.112-0.129 μg/mL, respectively. Intra- and inter-day precision expressed as relative standard deviations (RSD) were less than 3.1%, and the accuracy based on recovery test was ranging from 97% to 105%. Stability of the analytes within 1 day was found in the range between 1.34% and 2.93% (RSD). In addition, based on the amount of these four compounds combining with the discriminant analysis, a reliable and accurate method was developed for discrimination of three ginger varieties found in Indonesia. The results indicated that the developed method could be used as quality control for ginger raw material and its related products. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of a stability-indicating CE assay for the determination of amlodipine enantiomers in commercial tablets.

PubMed

Fakhari, Ali Reza; Nojavan, Saeed; Haghgoo, Soheila; Mohammadi, Ali

2008-11-01

A simple, accurate, precise and sensitive method using CD for separation and stability indicating assay of enantiomers of amlodipine in the commercial tablets has been established. Several types of CD were evaluated and best results were obtained using a fused-silica capillary with phosphate running buffer (100 mM, pH 3.0) containing 5 mM hydroxypropyl-alpha-CD. The method has shown adequate separation for amlodipine enantiomers from its degradation products. The drug was subjected to oxidation, hydrolysis, photolysis and heat to apply stress conditions. The range of quantitation for both enantiomers was 5-150 microg/mL. Intra- and inter-day RSD (n=6) was <4%. The limit of quantification that produced the requisite precision and accuracy was found to be 5 microg/mL for both enantiomers. The LOD for both enantiomers was found to be 0.5 microg/mL. Degradation products produced as a result of stress studies did not interfere with the detection of enantiomers and the assay can thus be considered stability indicating.

Multifamily determination of pesticide residues in soya-based nutraceutical products by GC/MS-MS.

PubMed

Páleníková, Agneša; Martínez-Domínguez, Gerardo; Arrebola, Francisco Javier; Romero-González, Roberto; Hrouzková, Svetlana; Frenich, Antonia Garrido

2015-04-15

An analytical method based on a modified QuEChERS extraction coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) was evaluated for the determination of 177 pesticides in soya-based nutraceutical products. The QuEChERS method was optimised and different extraction solvents and clean-up approaches were tested, obtaining the most efficient conditions with a mixture of sorbents (PSA, C18, GBC and Zr-Sep(+)). Recoveries were evaluated at 10, 50 and 100 μg/kg and ranged between 70% and 120%. Precision was expressed as relative standard deviation (RSD), and it was evaluated for more than 160 pesticides as intra and inter-day precision, with values always below 20% and 25%, respectively. Limits of detection (LODs) ranged from 0.1 to 10 μg/kg, whereas limits of quantification (LOQs) from 0.5 to 20 μg/kg. The applicability of the method was proved by analysing soya-based nutraceuticals. Two pesticides were found in these samples, malathion and pyriproxyfen, at 11.1 and 1.5 μg/kg respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Quantification of almond skin polyphenols by liquid chromatography-mass spectrometry.

PubMed

Bolling, Bradley W; Dolnikowski, Gregory; Blumberg, Jeffrey B; Oliver Chen, C Y

2009-01-01

Reverse phase HPLC coupled to negative mode electrospray ionization (ESI) mass spectrometry (MS) was used to quantify 16 flavonoids and 2 phenolic acids from almond skin extracts. Calibration curves of standard compounds were run daily and daidzein was used as an internal standard. The inter-day relative standard deviation (RSD) of standard curve slopes ranged from 13% to 25% of the mean. On column (OC) limits of detection (LOD) for polyphenols ranged from 0.013 to 1.4 pmol, and flavonoid glycosides had a 7-fold greater sensitivity than aglycones. Limits of quantification were 0.043 to 2.7 pmol OC, with a mean of 0.58 pmol flavonoid OC. Mean inter-day RSD of polyphenols in almond skin extract was 6.8% with a range of 4% to 11%, and intra-day RSD was 2.4%. Liquid nitrogen (LN(2)) or hot water (HW) blanching was used to facilitate removal of the almond skins prior to extraction using assisted solvent extraction (ASE) or steeping with acidified aqueous methanol. Recovery of polyphenols was greatest in HW blanched almond extracts with a mean value of 2.1 mg/g skin. ASE and steeping extracted equivalent polyphenols, although ASE of LN(2) blanched skins yielded 52% more aglycones and 23% less flavonoid glycosides. However, the extraction methods did not alter flavonoid profile of HW blanched almond skins. The recovery of polyphenolic components that were spiked into almond skins before the steeping extraction was 97% on a mass basis. This LC-MS method presents a reliable means of quantifying almond polyphenols.

Quantification of Almond Skin Polyphenols by Liquid Chromatography-Mass Spectrometry

PubMed Central

Bolling, Bradley W.; Dolnikowski, Gregory; Blumberg, Jeffrey B.; Oliver Chen, C.Y.

2014-01-01

Reverse phase HPLC coupled to negative mode electrospray ionization (ESI) mass spectrometry (MS) was used to quantify 16 flavonoids and 2 phenolic acids from almond skin extracts. Calibration curves of standard compounds were run daily and daidzein was used as an internal standard. The inter-day relative standard deviation (RSD) of standard curve slopes ranged from 13% to 25% of the mean. On column (OC) limits of detection (LOD) for polyphenols ranged from 0.013 to 1.4 pmol, and flavonoid glycosides had a 7-fold greater sensitivity than aglycones. Limits of quantification were 0.043 to 2.7 pmol OC, with a mean of 0.58 pmol flavonoid OC. Mean inter-day RSD of polyphenols in almond skin extract was 6.8% with a range of 4% to 11%, and intra-day RSD was 2.4%. Liquid nitrogen (LN2) or hot water (HW) blanching was used to facilitate removal of the almond skins prior to extraction using assisted solvent extraction (ASE) or steeping with acidified aqueous methanol. Recovery of polyphenols was greatest in HW blanched almond extracts with a mean value of 2.1 mg/g skin. ASE and steeping extracted equivalent polyphenols, although ASE of LN2 blanched skins yielded 52% more aglycones and 23% less flavonoid glycosides. However, the extraction methods did not alter flavonoid profile of HW blanched almond skins. The recovery of polyphenolic components that were spiked into almond skins before the steeping extraction was 97% on a mass basis. This LC-MS method presents a reliable means of quantifying almond polyphenols. PMID:19490319

Microbiological assay for the determination of meropenem in pharmaceutical dosage form.

PubMed

Mendez, Andreas S L; Weisheimer, Vanessa; Oppe, Tércio P; Steppe, Martin; Schapoval, Elfrides E S

2005-04-01

Meropenem is a highly active carbapenem antibiotic used in the treatment of a wide range of serious infections. The present work reports a microbiological assay, applying the cylinder-plate method, for the determination of meropenem in powder for injection. The validation method yielded good results and included linearity, precision, accuracy and specificity. The assay is based on the inhibitory effect of meropenem upon the strain of Micrococcus luteus ATCC 9341 used as the test microorganism. The results of assay were treated statistically by analysis of variance (ANOVA) and were found to be linear (r=0.9999) in the range of 1.5-6.0 microg ml(-1), precise (intra-assay: R.S.D.=0.29; inter-assay: R.S.D.=0.94) and accurate. A preliminary stability study of meropenem was performed to show that the microbiological assay is specific for the determination of meropenem in the presence of its degradation products. The degraded samples were also analysed by the HPLC method. The proposed method allows the quantitation of meropenem in pharmaceutical dosage form and can be used for the drug analysis in routine quality control.

Analysis of DDT and its metabolites in soil and water samples obtained in the vicinity of a closed-down factory in Bangladesh using various extraction methods.

PubMed

Al Mahmud, M N U; Khalil, Farzana; Rahman, Md Musfiqur; Mamun, M I R; Shoeb, Mohammad; Abd El-Aty, A M; Park, Jong-Hyouk; Shin, Ho-Chul; Nahar, Nilufar; Shim, Jae-Han

2015-12-01

This study was conducted to monitor the spread of dichlorodiphenyltrichloroethane (DDT) and its metabolites (dichlorodiphenyldichloroethylene (DDE), dichlorodiphenyldichloroethane (DDD)) in soil and water to regions surrounding a closed DDT factory in Bangladesh. This fulfillment was accomplished using inter-method and inter-laboratory validation studies. DDTs (DDT and its metabolites) from soil samples were extracted using microwave-assisted extraction (MAE), supercritical fluid extraction (SFE), and solvent extraction (SE). Inter-laboratory calibration was assessed by SE, and all methods were validated by intra- and inter-day accuracy (expressed as recovery %) and precision (expressed as relative standard deviation (RSD)) in the same laboratory, at three fortified concentrations (n = 4). DDTs extracted from water samples by liquid-liquid partitioning and all samples were analyzed by gas chromatography (GC)-electron capture detector (ECD) and confirmed by GC/mass spectrometry (GC/MS). Linearities expressed as determination coefficients (R (2)) were ≥0.995 for matrix-matched calibrations. The recovery rate was in the range of 72-120 and 83-110%, with <15% RSD in soil and water, respectively. The limit of quantification (LOQ) was 0.0165 mg kg(-1) in soil and 0.132 μg L(-1) in water. Greater quantities of DDTs were extracted from soil using the MAE and SE techniques than with the SFE method. Higher amounts of DDTs were discovered in the southern (2.2-936 × 10(2) mg kg(-1)) or southwestern (86.3-2067 × 10(2) mg kg(-1)) direction from the factory than in the eastern direction (1.0-48.6 × 10(2) mg kg(-1)). An exception was the soil sample collected 50 ft (15.24 m) east (2904 × 10(2) mg kg(-1)) of the factory. The spread of DDTs in the water bodies (0.59-3.01 μg L(-1)) was approximately equal in all directions. We concluded that DDTs might have been dumped randomly around the warehouse after the closing of the factory.

High performance liquid chromatography analysis of aliphatic thiols in alimentary supplements and pharmaceuticals using menadione as a new useful derivatization reagent.

PubMed

Gatti, Rita; Vitellaro, Valeria

2013-12-04

The use of menadione (MD) as a pre-column reagent for high performance liquid chromatography (HPLC) analysis of aliphatic thiols is proposed. The reaction was carried out for 5 min at room temperature and pH 8.5. The developed method was applied to the N-acetylcysteine (NAC) analysis of alimentary supplements and pharmaceutical formulations. The effect of the complex matrix was evaluated by the study of the thiol derivatization reaction both in standard and in placebo solutions. The yield of NAC-MD adduct was found to be quantitative at a reagent to thiol molar ratio of about 4 in comparison with an authentic specimen of synthesized NAC adduct, which was characterized by (1)H NMR, IR and UV. The routine chromatographic separations were performed on a Synergi MAX-RP column using a mobile phase consisting of methanol/triethylammonium (TEA) phosphate buffer (pH 3; 0.05 mol L(-1)) 70:30 (v/v) at a flow-rate of 0.4 mL min(-1). UV-diode array detection was used setting the wavelength at λ=260 nm. The validation parameters such as linearity, sensitivity, accuracy, precision, selectivity and ruggedness were found to be highly satisfactory. Similar linear responses were observed by standard and placebo solutions (determination coefficient: 0.9996). Limit of detection was about 0.019 μg g(-1). Intra-day precision (relative standard deviation, R.S.D.) was ≤0.81% for NAC to internal standard (IS) peak area ratio, ≤0.28% and ≤0.32%, respectively, for NAC and IS retention times (tR), without significant differences between intra- and inter-day data. NAC recovery studies gave good results (100.12%) with R.S.D.=1.05%. Copyright © 2013 Elsevier B.V. All rights reserved.

An high-performance liquid chromatographic method for the simultaneous analysis of acetylcarnitine taurinate, carnosine, asparagine and potassium aspartate and for the analysis of phosphoserine in alimentary supplements.

PubMed

Gatti, R; Andreatta, P; Boschetti, S

2013-07-12

A RP-HPLC method with pre-column derivatization was developed and validated for the simultaneous quantification of carnosine (Carn), acetylcarnitine taurinate (AC-Tau), asparagine (Asn), potassium aspartate (Asp) and for the determination of phosphoserine (p-Ser) in new and commercial alimentary supplements. The effect of complex matrices was evaluated by the study of the amino acid derivatization reaction with 2,4-dinitrofluorobenzene (DNFB) both in standard and placebo solutions. The reaction was carried out for 20 min at 70 °C in alkaline medium (pH10) for p-Ser analysis, whereas for 60 min in the case of Carn, AC-Tau, Asn and Asp analysis. The adducts have been separated on a Discovery RP Amide C16 (250 mm×4.6mm, i.d.) column using a mobile phase consisting of acetonitrile (ACN) and triethylammonium (TEA) phosphate buffer (pH 3, 0.05 M) under gradient elution conditions at a flow-rate of 0.8 mL/min. Detection was set at λ=360 nm. The validation parameters such as linearity, sensitivity, accuracy, precision and specificity were found to be highly satisfactory. Linear responses were observed by placebo solutions (determination coefficient ≤0.9996). Intra-day precision (relative standard deviation, RSD) was ≤1.06% for corrected peak area and ≤0.99% for retention times (tR) without significant differences between intra- and inter-day data. Recovery studies showed good results for all examined compounds (from 97.7% to 101.5%) with RSD ranging from 0.5% to 1.3%). The high stability of derivatized compound solutions at room temperature means an undoubted advantage of the method allowing the simultaneous preparation of a large number of samples and consecutive chromatographic analyses by the use of an autosampler. The developed method can be considered suitable for the quality control of new and commercial products. Copyright © 2013 Elsevier B.V. All rights reserved.

Application of mixed cloud point extraction for the analysis of six flavonoids in Apocynum venetum leaf samples by high performance liquid chromatography.

PubMed

Zhou, Jun; Sun, Jiang Bing; Xu, Xin Yu; Cheng, Zhao Hui; Zeng, Ping; Wang, Feng Qiao; Zhang, Qiong

2015-03-25

A simple, inexpensive and efficient method based on the mixed cloud point extraction (MCPE) combined with high performance liquid chromatography was developed for the simultaneous separation and determination of six flavonoids (rutin, hyperoside, quercetin-3-O-sophoroside, isoquercitrin, astragalin and quercetin) in Apocynum venetum leaf samples. The non-ionic surfactant Genapol X-080 and cetyl-trimethyl ammonium bromide (CTAB) was chosen as the mixed extracting solvent. Parameters that affect the MCPE processes, such as the content of Genapol X-080 and CTAB, pH, salt content, extraction temperature and time were investigated and optimized. Under the optimized conditions, the calibration curve for six flavonoids were all linear with the correlation coefficients greater than 0.9994. The intra-day and inter-day precision (RSD) were below 8.1% and the limits of detection (LOD) for the six flavonoids were 1.2-5.0 ng mL(-1) (S/N=3). The proposed method was successfully used to separate and determine the six flavonoids in A. venetum leaf samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid screening of selective serotonin re-uptake inhibitors in urine samples using solid-phase microextraction gas chromatography-mass spectrometry.

PubMed

Salgado-Petinal, Carmen; Lamas, J Pablo; Garcia-Jares, Carmen; Llompart, Maria; Cela, Rafael

2005-07-01

In this paper a solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) method is proposed for a rapid analysis of some frequently prescribed selective serotonin re-uptake inhibitors (SSRI)-venlafaxine, fluvoxamine, mirtazapine, fluoxetine, citalopram, and sertraline-in urine samples. The SPME-based method enables simultaneous determination of the target SSRI after simple in-situ derivatization of some of the target compounds. Calibration curves in water and in urine were validated and statistically compared. This revealed the absence of matrix effect and, in consequence, the possibility of quantifying SSRI in urine samples by external water calibration. Intra-day and inter-day precision was satisfactory for all the target compounds (relative standard deviation, RSD, <14%) and the detection limits achieved were <0.4 ng mL(-1) urine. The time required for the SPME step and for GC analysis (30 min each) enables high throughput. The method was applied to real urine samples from different patients being treated with some of these pharmaceuticals. Some SSRI metabolites were also detected and tentatively identified.

[Determination of total protein content in soya-bean milk via visual moving reaction boundary titration].

PubMed

Guo, Chengye; Wang, Houyu; Zhang, Lei; Fan, Liuyin; Cao, Chengxi

2013-11-01

A visual, rapid and accurate moving reaction boundary titration (MRBT) method was used for the determination of the total protein in soya-bean milk. During the process, moving reaction boundary (MRB) was formed by hydroxyl ions in the catholyte and soya-bean milk proteins immobilized in polyacrylamide gel (PAG), and an acid-base indicator was used to denote the boundary motion. The velocity of MRB has a relationship with protein concentration, which was used to obtain a standard curve. By paired t-test, there was no significant difference of the protein content between MRBT and Kjeldahl method at 95% confidence interval. The procedure of MRBT method required about 10 min, and it had linearity in the range of 2.0-14.0 g/L, low limit of detection (0.05 g/L), good precision (RSD of intra-day < 1.90% and inter-day < 4.39%), and high recoveries (97.41%-99.91%). In addition, non-protein nitrogen (NPN) such as melamine added into the soya-bean milk had weak influence on MRBT results.

Simultaneous analysis of eight bioactive compounds in Danning tablet by HPLC-ESI-MS and HPLC-UV.

PubMed

Liu, Runhui; Zhang, Jiye; Liang, Mingjin; Zhang, Weidong; Yan, Shikai; Lin, Min

2007-02-19

A high performance liquid chromatography (HPLC) coupled with electrospray tandem mass spectrometry (ESI-MS) and ultraviolet detector (UV) has been developed for the simultaneous analysis of eight bioactive compounds in Danning tablet (including hyperin, hesperidin, resveratrol, nobiletin, curcumine, emodin, chrysophanol, and physcion), a widely used prescription of traditional Chinese medicine (TCM). The chromatographic separation was performed on a ZORBAX Extend C(18) analytical column by gradient elution with acetonitrile and formate buffer (containing 0.05% formic acid, adjusted with triethylamine to pH 5.0) at a flow rate of 0.8 ml/min. The eight compounds in Danning tablet were identified and their MS(n) fractions were elucidated by using HPLC-ESI-MS, and the contents of these compounds were determined by using HPLC-UV method. The standard calibration curves were linear between 5.0 and 100 microg/ml for hyperin, 10-200 microg/ml for hesperidin, 1.0-150 microg/ml for resveratrol, 2.0-120 microg/ml for nobiletin, 2.0-225 microg/ml for curcumine, 20-300 microg/ml for emodin, 2.0-200 microg/ml for chrysophanol, and 20-250 microg/ml for physcion with regression coefficient r(2)>0.9995. The intra-day and inter-day precisions of this method were evaluated with the R.S.D. values less than 0.7% and 1.3%, respectively. The recoveries of the eight investigated compounds were ranged from 99.3% to 100.2% with R.S.D. values less than 1.5%. This method was successfully used to determine the 8 target compounds in 10 batches of Danning tablet.

Quantitative LC-MS/MS analysis of seven ginsenosides and three aconitum alkaloids in Shen-Fu decoction

PubMed Central

2013-01-01

Background Shen-Fu decoction is a traditional Chinese medicine prescription with a 3:2 ratio of Radix Ginseng and Fuzi (Radix Aconiti lateralis praeparata). Ginsenosides and alkaloids are considered to be the main active components of Shen-Fu decoction. However, no analytical methods have been used to quantitatively analyse both components in Shen-Fu decoction simultaneously. Results We successfully developed a rapid resolution liquid chromatography coupled with tandem mass spectrometry (RRLC-MS/MS) method for the simultaneous analysis of seven ginsenosides and three aconitum alkaloids in Shen-Fu decoction, the decoction of Radix ginseng and Fuzi (Radix Aconiti lateralis praeparata). Chromatogrpahic separation by RPLC was achieved using a reversed-phase column and a water/acetonitrile mobile phase, containing 0.05% formic acid and using a gradient system. The method was optimized to allow for simultaneous analysis of all analytes in 11minutes without the need for baseline resolution of the components. Furthermore, the separation demonstrated good linearity (r > 0.9882), repeatability (RSD < 7.01%), intra- and inter-day precisions (RSD < 5.06%) and high yields of recovery (91.13-111.97%) for ten major constituents, namely ginsenoside-Re, Rg1, Rb1, Rc, Rb2, Rd, Rf, aconitine, hypacoitine and mesaconitine. Conclusions The developed method could be used as a rapid and reliable approach for assessment of the quantity of the major constituents in Shen-Fu decoction. PMID:24107599

Novel enzyme-linked immunosorbent assay for determination of fluvastatin in plasma at picogram level.

PubMed

Darwish, Ibrahim A; Al-Obaid, Abdul-Rahman M; Al-Malaq, Hamoud A

2009-11-15

For the first time, an enzyme-linked immunosorbent assay (ELISA) has been developed and validated for the determination of fluvastatin (FLV) in plasma samples at picogram level. The assay employed a polyclonal antibody that specifically recognizes FLV with high affinity, and FLV conjugate of bovine serum albumin (FLV-BSA) immobilized onto microplate wells as a solid-phase. The assay involved a competitive binding reaction between FLV, in plasma sample, and the immobilized FLV-BSA for the binding sites on a limited amount of the anti-FLV antibody. The bound anti-FLV antibody was quantified with horseradish peroxidase-labeled second anti-rabbit IgG antibody (HRP-IgG) and 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate for the peroxidase enzyme. The concentration of FLV in the sample was quantified by its ability to inhibit the binding of the anti-FLV antibody to the immobilized FLV-BSA and subsequently the color intensity in the assay wells. The conditions for the proposed ELISA were investigated and the optimum conditions were employed in the determination of FLV in plasma samples. The assay limit of detection was 10 pg mL(-1) and the effective working range at relative standard deviations (RSD) of

Simultaneous quantification of the organophosphorus pesticides dimethoate and omethoate in porcine plasma and urine by LC-ESI-MS/MS and flow-injection-ESI-MS/MS.

PubMed

John, Harald; Eddleston, Michael; Clutton, R Eddie; Worek, Franz; Thiermann, Horst

2010-05-15

Dimethoate is an organophosphorus toxicant used in agri- and horticulture as a systemic broad-spectrum insecticide. It also exhibits toxic activity towards mammalian organism provoked by catalytic desulfuration in the liver producing its oxon-derivative omethoate thus inhibiting acetylcholinesterase, initiating cholinergic crisis and ultimately leading to death by respiratory paralysis and cardiovascular collapse. Pharmaco- and toxicokinetic studies in animal models help to broaden basic understanding of medical intervention by antidotes and supportive care. Therefore, we developed and validated a LC-ESI-MS/MS method suitable for the simultaneous, selective, precise (RSD(intra-day) 1-8%; RSD(inter-day) 5-14%), accurate (intra-day: 95-107%; inter-day: 90-115%), and robust quantification of both pesticides from porcine urine and plasma after deproteinization by precipitation and extensive dilution (1:11,250 for plasma and 1:40,000 for urine). Accordingly, lower limits of quantification (0.24-0.49 microg/ml plasma and 0.78-1.56 microg/ml urine) and lower limits of detection (0.12-0.24 microg/ml plasma and 0.39-0.78 microg/ml urine) were equivalent to quite low absolute on-column amounts (1.1-2.1 pg for plasma and 2.0-3.9 pg for urine). The calibration range (0.24-250 microg/ml plasma and 0.78-200 microg/ml urine) was subdivided into two linear ranges (r(2)>or=0.998) each covering nearly two orders of magnitude. The lack of any interfering peak in 6 individual blank specimens from plasma and urine demonstrated the high selectivity of the method. Furthermore, extensive sample dilution causing lowest concentration of potentially interfering matrix ingredients prompted us to develop and validate an additional flow-injection method (FI-ESI-MS/MS). Validation characteristics were as good as for the chromatographic method but sample throughput was enhanced by a factor of 6. Effects on ionization provoked by plasma and urine matrix from 6 individuals as well as in the presence of therapeutics (antidotes) administered in an animal study were investigated systematically underlying in the reliability of the presented methods. Both methods were applied to porcine samples derived from an in vivo animal study. Copyright (c) 2010 Elsevier B.V. All rights reserved.

[Determination of content and entrapment efficiency of 20 (S)-protopanaxadiol in pharmacosomes by RP-HPLC method].

PubMed

Han, Meihua; Chen, Jing; Chen, Shilin; Wang, Xiangtao

2009-05-01

To establish a RP-HPLC method for content and entrapment efficiency of 20 (S)-protopanaxadiol in pharmacosomes. The separation was performed with a COSMOSIL 5 C18-MS-II column (4.6 mm x 250 mm, 5 mmicrom) using methanol-water (95:5) as the mobile phase and detected at 203 nm. The flow rate was 1.0 mL x min(-1) and 50 microL sample solution was injected for each time. The calibration curve was linear within the range 0.1-0.5 mg x mL(-1) (r = 0. 9999) , the intra-day RSD and inter-day RSD were less than 2% and the average recovery was between 101.44%-103.11% (n = 3). The method is simple, accurate, sensitive and applicable for determination of content and entrapment efficiency of 20 (S)-protopanaxadiol pharmacosomes.

Simultaneous LC-MS/MS determination of five tripterygium pyridine alkaloids in dog plasma and its application to their pharmacokinetic study after oral administration of tripterygium glycosides tablets.

PubMed

Su, Meng-xiang; Song, Min; Yang, Da-song; Shi, Jin-fang; Di, Bin; Hang, Tai-jun

2015-05-15

A sensitive and selective liquid chromatography tandem mass spectrometric method was developed and validated for the simultaneous determination of five pyridine alkaloids contained in tripterygium glycosides tablets (triptolide, wilforine, wilforgine, wilfording and wilfortrine) in dog plasma. The analysis was carried out on a Sepax GP-Phenyl column using a mixture of methanol and 10mmol/L ammonium formate buffer solution containing 0.1% formic acid (75:25, v/v) as the mobile phase pumped at a flow-rate of 1.0mL/min. All MS data were obtained in the positive ESI mode with selective multiple reaction monitoring of ion transitions. The method was fully validated to be accurate and precise with a linear range of 0.2-1000ng/mL for triptolide and 0.05-1000ng/mL for the other four pyridine alkaloids. The intra-day and inter-day precisions (relative standard deviation, RSD, %) were within 10.6% and 14.0%, respectively, and the relative error (RE, %) were all less than 13.1%. The method was successfully applied to multi-components pharmacokinetic study of the five pyridine alkaloids in beagle dogs after a single oral administration of 3mg/kg and 30mg/kg tripterygium glycosides tablets, respectively, and a multiple oral administration of 30mg/kg for 6 consecutive days. Copyright © 2015 Elsevier B.V. All rights reserved.

Magnetic graphene coated inorganic-organic hybrid nanocomposite for enhanced preconcentration of selected pesticides in tomato and grape.

PubMed

Rashidi Nodeh, Hamid; Sereshti, Hassan; Gaikani, Hamid; Kamboh, Muhammad Afzal; Afsharsaveh, Zahra

2017-08-04

The new magnetic graphene based hybrid silica-N-[3-(trimethoxysilyl)propyl]ethylenediamine (MG@SiO 2 -TMSPED) nanocomposite was synthesized via sol-gel process, and used as an effective adsorbent in magnetic solid phase extraction (MSPE) of three selected pesticides followed by gas chromatography micro-electron capture detection (GC-μECD). The adsorbent was characterized using Fourier transform-infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDXS) techniques. The analytical validity of the developed method was evaluated under optimized conditions and the following figures of merit were obtained: linearity, 1-20μgkg -1 with good determination coefficients (R 2 =0.995-0.999); limits of detection (LODs), 0.23-0.30μgkg -1 (3×SD/m, n=3); and limits of quantitation (LOQ), 0.76-1.0μgkg -1 (10×SD/m, n=3). The precision (RSD%) of the proposed MSPE method was studied based on intra-day (3.43-8.83%, n=3) and inter-day (6.68-8.37%, n=12) precisions. Finally, the adsorbent was applied to determination of pesticides in tomato and grape samples and good recoveries were obtained in the range from 82 to 113% (RSDs 5.1-8.1%, n=3). Copyright © 2017 Elsevier B.V. All rights reserved.

A simple LC method with UV detection for the analysis of creatine and creatinine and its application to several creatine formulations.

PubMed

Dash, Alekha K; Sawhney, Angeli

2002-07-31

The objective of this study was to develop a simple and sensitive LC method for the determination of creatine and creatinine in various creatine supplement formulations. The chromatographic system comprised of a LC-600 pump, SCL-6B system controller, and SPD-6AV detector (Shimadzu, Japan). The mobile phase consisted of 0.045 M ammonium sulfate in water. The chromatographic separation was achieved at ambient temperature on a Betabasic C-18 column (250 x 4.6 mm, Keystone Sci.). The flow rate was maintained at 0.75 ml/min and effluents are monitored at 205 nm. 4-(2-Aminoethyl)benzene sulfonamide was used as an internal standard (IS). This method required less than 7 min of chromatographic time. The standard curves were linear over the concentration range of 1-100 microg/ml for creatine and 2-100 microg/ml for creatinine, respectively. The relative standard deviations (RSD) for the within-day and day-to-day precision for creatine were within 1.0-4.6 and 2.2-4.7%, respectively. The RSD for the accuracy of creatine assay was in the range of 2.4-4.7%. The RSD values for the within-day precision, day-to-day precision and accuracy for creatinine validation were 1.7-4.4, 2.3-5.4 and 2.4-4.8%, respectively. This method was used to determine: (i) the creatine concentration in various marketed products; (ii) saturated solubility of various creatine salts; and (iii) stability of creatine in aqueous solution. In conclusion, a simple and sensitive LC method with UV detection was developed for the simultaneous determination of creatine and creatinine in formulations. Di-creatine citrate salt showed a higher aqueous solubility (at 25 degrees C) as compared to creatine and creatine monohydrate. Some of the over-the-counter (OTC) products tested contained a very low level of creatine in contrast to their label claim. Substantial conversion of creatine into creatinine was noticed in liquid formulation.

Development and validation of a stability-indicating LC method for the assay of lodenafil carbonate in tablets.

PubMed

Codevilla, Cristiane Franco; Lemos, Alice Machado; Delgado, Leila Schreiner; Rolim, Clarice Madalena Bueno; Adams, Andréa Inês Horn; Bergold, Ana Maria

2011-08-01

A stability-indicating liquid chromatographic method has been developed for the quantitative determination of lodenafil carbonate in tablets. The method employs a Synergi Fusion C18 column (250 × 4.6 mm, i.d., 4 μm particle size), with mobile phase consisting of a mixture of methanol-acetic acid 0.1% pH 4.0 (65:35, v/v) and UV detection at 290 nm, using a photodiode array detector. A linear response (r = 0.9999) was observed in the range of 10-80 μg/mL. The method showed good recoveries (average 100.3%) and also intra and inter-day precision (RSD < 2.0%). Validation parameters as specificity and robustness were also determined. Specificity analysis showed that no impurities or degradation products were co-eluting with the lodenafil carbonate peak. The method was found to be stability-indicating and due to its simplicity and accuracy can be applied for routine quality control analysis of lodenafil carbonate in tablets.

A quantitative approach for pesticide analysis in grape juice by direct interfacing of a matrix compatible SPME phase to dielectric barrier discharge ionization-mass spectrometry.

PubMed

Mirabelli, Mario F; Gionfriddo, Emanuela; Pawliszyn, Janusz; Zenobi, Renato

2018-02-12

We evaluated the performance of a dielectric barrier discharge ionization (DBDI) source for pesticide analysis in grape juice, a fairly complex matrix due to the high content of sugars (≈20% w/w) and pigments. A fast sample preparation method based on direct immersion solid-phase microextraction (SPME) was developed, and novel matrix compatible SPME fibers were used to reduce in-source matrix suppression effects. A high resolution LTQ Orbitrap mass spectrometer allowed for rapid quantification in full scan mode. This direct SPME-DBDI-MS approach was proven to be effective for the rapid and direct analysis of complex sample matrices, with limits of detection in the parts-per-trillion (ppt) range and inter- and intra-day precision below 30% relative standard deviation (RSD) for samples spiked at 1, 10 and 10 ng ml -1 , with overall performance comparable or even superior to existing chromatographic approaches.

A novel liquid chromatography method using diode-array detector for the determination of oleuropein in dietary supplements.

PubMed

Bertolini, Tiziana; Vicentini, Lorenza; Boschetti, Silvia; Andreatta, Paolo; Gatti, Rita

2016-09-10

A simple and fast chromatographic method using ultraviolet diode-array detector (UV-DAD) was developed for the automatic high performance liquid chromatography (HPLC) determination of the title of oleuropein in a new dietary supplements in form of effervescent granules. The chromatographic separations were performed on a C18 core-shell column with detection at λ=232nm. The mobile phase consisted of deionized water with 0.1% TFA and acetonitrile under gradient conditions at a flow-rate of 0.8mL/min. Oleuropein and oleuroside present in the raw material were characterized by high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The validation of the analytical procedure has been performed determining the following parameters: specificity, linearity, repeatability, reproducibility, accuracy, limit of quantification (LOQ), stability of the standard and sample solutions. Linear response was observed in fortified placebo solutions (determination coefficient: 0.9998). Intra-day precision (relative standard deviation, RSD) was ≤5.0% for peak area and for retention times (tR) without significant differences between intra- and inter-day data. The limits of quantitation (LOQ) was about 5μg/mL and 9pmol/inject. Oleuropein recovery studies gave good results (99.9%) with a R.S.D. of 0.5%. The speed of analysis and the stability of the solutions with a fluctuation Δ (%) ≤2.0 at room temperature means an undoubted advantage of the method allowing the simultaneous preparation of many samples and consecutive chromatographic analyses by using an autosampler. The developed method is suitable for the quality control of oleuropein in raw material and industrial products. The method can be applied in any analytical laboratory not requiring a sophisticated instrumentation. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative analysis of the main bioactive components of San-ao decoction and its series of formulations.

PubMed

Shu, Xiaoyun; Tang, Yuping; Jiang, Chenxue; Shang, Erxing; Fan, Xinshen; Ding, Anwei

2012-11-01

A high performance liquid chromatographic (HPLC) method with diode array detection (DAD) was established for simultaneous determination of seven main bioactive components in San-ao decoction and its series of formulae (San-ao decoction, Wu-ao decoction, Qi-ao decoction and Jia-wei San-ao decoction). Seven compounds were analyzed simultaneously with a XTerra C(18) column (4.6 mm × 250 mm, 5 µm) using a linear gradient elution of a mobile phase containing acetonitrile (A) and a buffer solution (0.02 mol/L potassium dihydrogen phosphate and adjusted to pH 3 using phosphoric acid) (B); the flow rate was 1.0 mL/min. The sample was detected with DAD at 210, 254 and 360 nm and the column was maintained at 30 °C. All the compounds showed good linearity (r2 > 0.9984) in the tested concentration range. The precisions were evaluated by intra-day and inter-day tests, and relative standard deviation (R.S.D.) values within the range of 0.83%–2.53% and 0.64%–2.77% were reported, respectively. The recoveries of the quantified compounds were observed to cover a range from 95.34% and 104.82% with R.S.D. values less than 2.72%. The validated method was successfully applied for the simultaneous determination of seven main bioactive components including ephedrine (1), amygdalin (2), liquiritin (3), benzoic acid (4), isoliquiritin (5), formononetin (6) and glycyrrhizic acid (7) in San-ao decoction and its series of formulae. The results also showed a wide variation in the content of the identified active compounds in these samples, which could also be helpful to illustrate the drug interactions after some herbs combined in different formulations.

Development and validation of an RP-HPLC method for quantification of cinnamic acid derivatives and kaurane-type diterpenes in Mikania laevigata and Mikania glomerata.

PubMed

Bertolucci, Suzan Kelly; Pereira, Ana Bárbara; Pinto, José Eduardo; de Aquino Ribeiro, José Antônio; de Oliveira, Alaíde Braga; Braga, Fernão Castro

2009-02-01

MIKANIA GLOMERATA and MIKANIA LAEVIGATA (Asteraceae) are medicinal plants popularly named 'guaco' in Brazil. The leaves of both species are used to treat respiratory diseases, with coumarin (CO) and kaurane-type diterpenes being regarded as the bioactive constituents. A new and simple RP-HPLC method was developed and validated for the simultaneous quantification of CO, O-coumaric (OC), benzoylgrandifloric (BA), cinnamoylgrandifloric (CA) and kaurenoic (KA) acids in the species. Optimal separation was achieved with an alternating gradient elution of methanol and acetonitrile and detection was carried out by DAD at three different wavelengths: 210 nm for CO, OC, KA; 230 nm for BA; and 270 nm for CA. The extracts showed good stability during 42 hours under normal laboratory conditions (temperature of 23 +/- 2 degrees C). The standard curves were linear over the range 0.5 - 5.0 microg (CO), 0.25 - 4.0 microg (OC), 1.0 - 8.0 microg (BA), 0.5 - 3.0 microg (CA) and 0.8 - 12.0 microg (KA), with R(2) > 0.999 for all compounds. The method showed good precision for intra-day (RSD < 4.6 %) and inter-day assays (RSD < 4.4 %). The recovery was between 99.9 and 105.3 %, except for CO and OC in M. glomerata (73.2 - 91.6 % and 86.3 - 117.4 %, respectively). The limits of quantification and detection were in the range of 0.025 - 0.800 microg and 0.007 - 0.240 microg. The method was tested for new and old columns, temperature variation (26 and 28 degrees C) and by different operators in the same laboratory. The method was successfully applied to samples of both species.

Simultaneous determination of six bioactive compounds in Evodiae Fructus by high-performance liquid chromatography with diode array detection.

PubMed

Tang, Xiaolong; Huang, Zhifang; Chen, Yan; Liu, Yunhua; Liu, Yuhong; Zhao, Junning; Yi, Jinhai

2014-02-01

A simple and reliable high-performance liquid chromatography method with diode array detection (HPLC-DAD) was developed and validated for the simultaneous determination of six bioactive components, rutaevine, limonin, evodiamine, rutaecarpine, N-formyldihydrorutaecarpine and dihydroevocarpine, in the traditional Chinese medicine Evodiae Fructus (Wuzhuyu in Chinese). HPLC separation was conducted on an Agilent Eclipse C18 column (4.6 × 150 mm, 5 µm) at 35°C with a mixture of mobile phase A [tetrahydrofuran-0.02% phosphoric acid (16 : 35)] and mobile phase B (acetonitrile) (gradient elution as follows: 0 min, 22% B; 23 min, 22% B; 24 min, 75% B) at a flow rate of 1 mL/min, and the DAD detection wavelength was set at 220 nm. A linear relationship within the range of investigated concentrations was observed for the six compounds, with correlation coefficients greater than 0.999. The average recovery yields of the six compounds ranged from 98.39 to 104.96%. The HPLC-DAD method was validated by its repeatability [relative standard deviation (RSD) < 2.0%] and intra-day and inter-day precision (RSD < 2.0%). The method was successfully applied to the simultaneous determination of the six previously mentioned components in Evodiae Fructus. It is the first report of a simultaneous qualitative and quantitative analysis for three classes of bioactive components in Wuzhuyu, including the indolequinazoline alkaloids, quinolone alkaloid and limonoids. Based on these results, it is suggested, for possible future revision of the Chinese Pharmacopoeia, that the total contents of evodiamine and rutaecarpine are not less than 0.15% and the total contents of rutaevine and limonin are not less than 0.50%.

A passive integrative sampler for mercury vapor in air and neutral mercury species in water

USGS Publications Warehouse

Brumbaugh, W.G.; Petty, J.D.; May, T.W.; Huckins, J.N.

2000-01-01

A passive integrative mercury sampler (PIMS) based on a sealed polymeric membrane was effective for the collection and preconcentration of Hg0. Because the Hg is both oxidized and stabilized in the PIMS, sampling intervals of weeks to months are possible. The effective air sampling rate for a 15 x 2.5 cm device was about 21-equivalents/day (0.002 m3/day) and the detection limit for 4-week sampling was about 2 ng/m3 for conventional ICP-MS determination without clean-room preparation. Sampling precision was ??? 5% RSD for laboratory exposures, and 5-10% RSD for field exposures. These results suggest that the PIMS could be useful for screening assessments of Hg contamination and exposure in the environment, the laboratory, and the workplace. The PIMS approach may be particularly useful for applications requiring unattended sampling for extended periods at remote locations. Preliminary results indicate that sampling for dissolved gaseous mercury (DGM) and potentially other neutral mercury species from water is also feasible. Rigorous validation of the sampler performance is currently in progress. (C) 1999 Elsevier Science Ltd.A passive integrative mercury sampler (PIMS) based on a sealed polymeric membrane was effective for the collection and preconcentration of Hg0. Because the Hg is both oxidized and stabilized in the PIMS, sampling intervals of weeks to months are possible. The effective air sampling rate for a 15??2.5 cm device was about 21-equivalents/day (0.002 m3/day) and the detection limit for 4-week sampling was about 2 ng/m3 for conventional ICP-MS determination without clean-room preparation. Sampling precision was ???5% RSD for laboratory exposures, and 5-10% RSD for field exposures. These results suggest that the PIMS could be useful for screening assessments of Hg contamination and exposure in the environment, the laboratory, and the workplace. The PIMS approach may be particularly useful for applications requiring unattended sampling for extended periods at remote locations. Preliminary results indicate that sampling for dissolved gaseous mercury (DGM) and potentially other neutral mercury species from water is also feasible. Rigorous validation of the sampler performance is currently in progress.

Simultaneous quantitative determination of bioactive terpene indole alkaloids in ethanolic extracts of Catharanthus roseus (L.) G. Don by ultra high performance liquid chromatography-tandem mass spectrometry.

PubMed

Kumar, Sunil; Singh, Awantika; Kumar, Brijesh; Singh, Bikarma; Bahadur, Lal; Lal, Mohan

2018-03-20

A rapid, sensitive and reproducible method using ultra-high-performance liquid chromatography coupled with electrospray ionization hybrid triple quadrupole-linear ion trap mass spectrometry (UHPLC-ESI-QqQ LIT -MS/MS) in multiple reaction monitoring (MRM) mode was developed and validated for simultaneous quantitation of anticancer (vincristine, vinblastine, vindesine), antihypertensive (ajmaline, ajmalicine, reserpine), aphrodisiac (yohimbine), sedative (serpentine) agents, dietary supplement (vinpocetine, yohimbine) and precursor of vinblastine (vindoline) from crude extracts of Catharanthus roseus. The precursor to product ion transitions for these compounds were observed at m/z 327 → 144, 355 → 144, 754 → 355, 353 → 144, 349 → 317, 825 → 225, 811 → 224, 458 → 188, 351 → 280 and 609 → 195, respectively in positive ionization mode. Chromatographic separation of all targeted TIAs was performed on ACQUITY UPLC BEH™ C 18 column (1.7 μm, 2.1 mm × 50 mm). The calibration curves were linear within the concentration range 0.5-1000 ng/mL and correlation coefficients (R 2 ) were closer to 1. Limit of detection (LOD) and limit of quantitation (LOQ) ranged from 0.039-0.583 ng/mL and 0.118-1.767 ng/mL, respectively. The intra-day (0.23-2.71% RSD) and inter-day (0.40-2.90% RSD) precision, stability (0.69-3.45% RSD) and recovery (99.63-104.30% ± %RSD ≤ 3.03%) were acceptable indicating good accuracy of the developed method. The method was successfully applied in ethanolic extracts of 39 samples of C. roseus parts (leaf, stem and root) collected from five different locations in India. Serpentine was detected as one of the most abundant TIA. Principal component analysis (PCA) was able to successfully discriminate among C. roseus samples on the basis of content of targeted TIAs. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of hydroxysafflor yellow A in rat plasma and tissues by high-performance liquid chromatography after oral administration of safflower extract or safflor yellow.

PubMed

Li, Yi; Zhang, Zhao-Yang; Zhang, Jin-Lan

2007-03-01

A simple and reproducible HPLC method for quantification of hydroxysafflor yellow A (HSYA) in rat plasma and tissues after oral administration of safflower extract or safflor yellow (SY) was developed. Sample preparation was achieved by protein precipitation of plasma and tissue homogenates with three volumes of methanol. p-Hydroxybenzaldehyde was used as the internal standard (IS). HSYA and IS were separated on a Hypersil BDS-C(18) column with a gradient elution system composed of acetonitrile and aqueous acetic acid. UV detection was used at 320 nm. The calibration curves were linear in all matrices (r(2) > 0.999) in the concentration ranges 0.51-101.36 microg/mL for plasma, 12.27-2454.46 microg/g for intestines and 0.96-192.20 microg/g for lung. The intra-day and inter-day precision were all less than 12.5%, and the extract recovery was in the range 64.1-103.7% with RSD less than 15.6% for HSYA in all matrices. The method was used successfully to quantify HSYA in rat plasma and tissue samples to support a pharmacokinectic study.

Fast analysis of 4-tertoctylphenol, pentachlorophenol and 4-nonylphenol in river sediments by QuEChERS extraction procedure combined with GC-QqQ-MS/MS.

PubMed

Czech, T; Bonilla, N Barco; Gambus, F; González, R Romero; Marín-Sáez, J; Vidal, J L Martínez; Frenich, A Garrido

2016-07-01

A quick, easy, cheap, effective, rugged and safe (QuEChERS)-based extraction method has been optimized for the determination of pentachlorophenol, 4-tertoctylphenol and 4-nonylphenol in river sediments. The extraction method was followed by gas chromatography-triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS) analysis, which ensures the reliable identification of the target compounds. The proposed method has been validated allowing the successful determination of the selected compounds, with recoveries ranging from 72 to 96%, when three concentration levels were evaluated (10, 50 and 100μgkg(-1)) and inter-day and intra-day precision, expressed as relative standard deviation (RSD), were lower than 20%. The method showed limits of detection (LODs) and limits of quantification (LOQs) ranging from 0.1 to 2.0μgkg(-1) and from 0.5 to 5.0μgkg(-1), respectively. Finally, 25 real samples from Poland have been analyzed, and only 4-tertoctylphenol was detected at concentrations up to 8.9μgkg(-1) of soil dry weight. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of piracetam in rat plasma by LC-MS/MS and its application to pharmacokinetics.

PubMed

Wang, Xianqin; Zhu, Jiayin; Xu, Renai; Yang, Xuezhi; Wu, Haiya; Lin, Dan; Ye, Faqing; Hu, Lufeng

2010-10-01

A sensitive and selective liquid chromatography-tandem mass spectrometry method for the determination of piracetam in rat plasma was developed and validated over the concentration range of 0.1-20 µg/mL. After addition of oxiracetam as internal standard, a simplified protein precipitation with trichloroacetic acid (5%) was employed for the sample preparation. Chromatographic separation was performed by a Zorbax SB-Aq column (150 × 2.1 mm, 3.5 µm). The mobile phase was acetonitrile-1% formic acid in water (10:90 v/v) delivered at a flow rate of 0.3 mL/min. The MS data acquisition was accomplished in multiple reaction monitoring mode with a positive electrospray ionization interface. The lower limit of quantification was 0.1 µg/mL. For inter-day and intra-day tests, the precision (RSD) for the entire validation was less than 9%, and the accuracy was within the 94.6-103.2% range. The developed method was successfully applied to pharmacokinetic studies of piracetam in rats following single oral administration dose of 50 mg/kg. Copyright © 2010 John Wiley & Sons, Ltd.

Simultaneous estimation of E- and Z-isomers of guggulsterone in rabbit plasma using liquid chromatography tandem mass spectrometry and its application to pharmacokinetic study.

PubMed

Bhatta, R S; Kumar, D; Chhonker, Y S; Jain, G K

2011-09-01

A sensitive and selective liquid chromatography/tandem mass spectrometric method was developed for simultaneous determination of E- and Z-guggulsterone isomers (antihyperlipidemic drug) in rabbit plasma. Both the isomers were resolved on a Symmetry-Shield C(18) (5 µm, 4.6 × 150 mm) column, using gradient elution comprising a mobile phase of methanol, 0.5% v/v formic acid and acetonitrile. With dexamethasone as internal standard, plasma samples were extracted by an automated solid-phase extraction method using C(18) cartridges. Detection was performed by electrospray ionization in multiple reaction monitoring (MRM) in positive mode. The calibration curve was linear over the concentration range of 1.56-200 ng/mL (r(2) ≥ 0.998) for both analytes. The intra-day and inter-day accuracy and precision were within -0.96 to 4.12 (%bias) and 2.73 to 8.00 (%RSD) respectively. The analytes were stable after three freeze-thaw cycles. The method was successfully applied to study steriospecific pharmacokinetics of E- and Z-guggulsterone in NZ rabbit. Copyright © 2011 John Wiley & Sons, Ltd.

A novel automated hydrophilic interaction liquid chromatography method using diode-array detector/electrospray ionization tandem mass spectrometry for analysis of sodium risedronate and related degradation products in pharmaceuticals.

PubMed

Bertolini, Tiziana; Vicentini, Lorenza; Boschetti, Silvia; Andreatta, Paolo; Gatti, Rita

2014-10-24

A simple, sensitive and fast hydrophilic interaction liquid chromatography (HILIC) method using ultraviolet diode-array detector (UV-DAD)/electrospray ionization tandem mass spectrometry was developed for the automated high performance liquid chromatography (HPLC) determination of sodium risedronate (SR) and its degradation products in new pharmaceuticals. The chromatographic separations were performed on Ascentis Express HILIC 2.7μm (150mm×2.1mm, i.d.) stainless steel column (fused core). The mobile phase consisted of formate buffer solution (pH 3.4; 0.03M)/acetonitrile 42:58 and 45:55 (v/v) for granules for oral solution and effervescent tablet analysis, respectively, at a flow-rate of 0.2mL/min, setting the wavelength at 262nm. Stability characteristics of SR were evaluated by performing stress test studies. The main degradation product formed under oxidation conditions corresponding to sodium hydrogen (1-hydroxy-2-(1-oxidopyridin-3-yl)-1-phosphonoethyl)phosphonate was characterized by high performance liquid chromatography-electrospray ionization-mass tandem mass spectrometry (HPLC-ESI-MS/MS). The validation parameters such as linearity, sensitivity, accuracy, precision and selectivity were found to be highly satisfactory. Linear responses were observed in standard and in fortified placebo solutions. Intra-day precision (relative standard deviation, RSD) was ≤1.1% for peak area and ≤0.2% for retention times (tR) without significant differences between intra- and inter-day data. Recovery studies showed good results for all the examined compounds (from 98.7 to 101.0%) with RSD ranging from 0.6 to 0.7%. The limits of detection (LOD) and quantitation (LOQ) were 1 and 3ng/mL, respectively. The high stability of standard and sample solutions at room temperature means an undoubted advantage of the method allowing the simultaneous preparation of many samples and consecutive chromatographic analyses by using an autosampler. The developed stability indicating method is suitable for the quality control of SR in new and commercial pharmaceutical formulations. Copyright © 2014 Elsevier B.V. All rights reserved.

[Determination of emamectin benzoate residue in vegetables by high performance liquid chromatography with fluorescence detection].

PubMed

Zhang, Yan; Wu, Yinliang; Hu, Jiye; Wang, Hongwei; Pan, Canping; Liu, Fengmao

2008-01-01

A method was developed for the determination of emamectin benzoate residue in cabbage and mushroom using solid-phase extraction (SPE) and high performance liquid chromatography (HPLC) with fluorescence detection. The sample was extracted with ethyl acetate. Further cleanup was performed on a propylsulfonic acid solid phase extraction cartridge, followed by the derivatization with trifluoroacetic anhydride in the presence of N-methylimidazole. The amount of derivatized emamectin benzoate was determined by fluorescence detector after separation by HPLC. The detection limit was 0.10 microg/kg for cabbage and mushroom samples. The recoveries of emamectin benzoate in cabbage and mushroom samples were 78.6%-84.9%. The inter-day relative standard deviation (RSD) and intra-day RSD were 2.7%-6.0% and 3.1%-8.9%, respectively, at the fortified levels of 1.0-20.0 microg/kg. The calibration curve of emamectin benzoate in vegetables at the concentration range of 0.002 mg/L to 0.10 mg/L was linear (r = 0.9999).

Simultaneous determination of mequindox, quinocetone, and their major metabolites in chicken and pork by UPLC-MS/MS.

PubMed

Li, Yanshen; Liu, Kaili; Beier, Ross C; Cao, Xingyuan; Shen, Jianzhong; Zhang, Suxia

2014-10-01

This report presents a UPLC-MS/MS method for determination of mequindox (MEQ), quinocetone (QCT) and their 11 metabolites in chicken and pork samples. Following extraction process with acetonitrile-ethyl acetate, acidulation, and re-extraction with ethyl acetate in turn, target analytes were further purified using C18 solid phase extraction (SPE) cartridges for UPLC-MS/MS analysis. Validation was processed with mean recoveries from 69.1% to 113.3% with intra-day relative standard deviation (RSD) <14.7%, inter-day RSD <19.2%, and limit of detection between 0.05 and 1.0 μg/kg for each analytes. The verified method was successfully applied to the quantitative determination of commercial samples. This developed procedure will help to control food animal products with MEQ and QCT residues, and facilitate further pharmacokinetic and residue studies of similar quinoxaline-1,4-dioxide veterinary drugs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Analysis of antithyroid drugs in surface water by using liquid chromatography-tandem mass spectrometry.

PubMed

Pérez-Fernández, Virginia; Marchese, Stefano; Gentili, Alessandra; García, María Ángeles; Curini, Roberta; Caretti, Fulvia; Perret, Daniela

2014-11-07

This paper describes development and validation of a new method for the simultaneous determination of six antithyroid drugs (ATDs) in surface waters by using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS). Target compounds include two ATD classes: thiouracil derivatives (thiouracil (TU), methyl-thiouracil (MTU), propyl-thiouracil (PTU), phenyl-thiouracil (PhTU)) and imidazole derivatives (tapazole (TAP), and mercaptobenzimidazole (MBI)). Sensitivity and selectivity of the LC-multiple reaction monitoring (MRM) analysis allowed applying a simple pre-concentration procedure and "shooting" the concentrated sample into the LC-MS/MS system without any other treatment. Recoveries were higher than 75% for all analytes. Intra-day precision and inter-day precision, calculated as relative standard deviation (RSD), were below 19 and 22%, respectively. Limits of detection (LODs) ranged from 0.05 to 0.25 μg/L; limits of quantitation (LOQs) varied between 0.15 and 0.75 μg/L. The validated method was successfully applied to the analysis of ATD residues in surface water samples collected from the Tiber River basin and three lakes of Lazio (central Italy). The analytes were quantified based on matrix-matched calibration curves with mercaptobenzimidazole-d4 (MBI-d4) as the internal standard (IS). The most widespread compound was TAP, one of the most common ATDs used in human medicine, but also TU and MBI were often detected in the analysed samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous spectrophotometric determination of glimepiride and pioglitazone in binary mixture and combined dosage form using chemometric-assisted techniques

NASA Astrophysics Data System (ADS)

El-Zaher, Asmaa A.; Elkady, Ehab F.; Elwy, Hanan M.; Saleh, Mahmoud Abo El Makarim

2017-07-01

In the present work, pioglitazone and glimepiride, 2 widely used antidiabetics, were simultaneously determined by a chemometric-assisted UV-spectrophotometric method which was applied to a binary synthetic mixture and a pharmaceutical preparation containing both drugs. Three chemometric techniques - Concentration residual augmented classical least-squares (CRACLS), principal component regression (PCR), and partial least-squares (PLS) were implemented by using the synthetic mixtures containing the two drugs in acetonitrile. The absorbance data matrix corresponding to the concentration data matrix was obtained by the measurements of absorbencies in the range between 215 and 235 nm in the intervals with Δλ = 0.4 nm in their zero-order spectra. Then, calibration or regression was obtained by using the absorbance data matrix and concentration data matrix for the prediction of the unknown concentrations of pioglitazone and glimepiride in their mixtures. The described techniques have been validated by analyzing synthetic mixtures containing the two drugs showing good mean recovery values lying between 98 and 100%. In addition, accuracy and precision of the three methods have been assured by recovery values lying between 98 and 102% and R.S.D. % ˂0.6 for intra-day precision and ˂1.2 for inter-day precision. The proposed chemometric techniques were successfully applied to a pharmaceutical preparation containing a combination of pioglitazone and glimepiride in the ratio of 30: 4, showing good recovery values. Finally, statistical analysis was carried out to add a value to the verification of the proposed methods. It was carried out by an intrinsic comparison between the 3 chemometric techniques and by comparing values of present methods with those obtained by implementing reference pharmacopeial methods for each of pioglitazone and glimepiride.

Rapid determination of retinoic acid and its main isomers in plasma by second-order high-performance liquid chromatography data modeling.

PubMed

Teglia, Carla M; Cámara, María S; Goicoechea, Héctor C

2014-12-01

This paper reports the development of a method based on high-performance liquid chromatography (HPLC) coupled to second-order data modeling with multivariate curve resolution-alternating least-squares (MCR-ALS) for quantification of retinoic acid and its main isomers in plasma in only 5.5 min. The compounds retinoic acid (RA), 13-cis-retinoic acid, 9-cis-retinoic acid, and 9,13-di-cis-retinoic acid were partially separated by use of a Poroshell 120 EC-C18 (3.0 mm × 30 mm, 2.7 μm particle size) column. Overlapping not only among the target analytes but also with the plasma interferents was resolved by exploiting the second-order advantage of the multi-way calibration. A validation study led to the following results: trueness with recoveries of 98.5-105.9 % for RA, 95.7-110.1 % for 13-cis-RA, 97.1-110.8 % for 9-cis-RA, and 99.5-110.9 % for 9,13-di-cis-RA; repeatability with RSD of 3.5-3.1 % for RA, 3.5-1.5 % for 13-cis-RA, 4.6-2.7 % for 9-cis-RA, and 5.2-2.7 % for 9,13-di-cis-RA (low and high levels); and intermediate precision (inter-day precision) with RSD of 3.8-3.0 % for RA, 2.9-2.4 % for 13-cis-RA, 3.6-3.2 % for 9,13-di-cis-RA, and 3.2-2.9 % for 9-cis-RA (low and high levels). In addition, a robustness study revealed the method was suitable for monitoring patients with dermatological diseases treated with pharmaceutical products containing RA and 13-cis-RA.

Optimizing high-performance liquid chromatography method for quantification of glucosamine using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate derivatization in rat plasma: application to a pharmacokinetic study.

PubMed

Wang, Xianhuo; Chen, Xiang; Chen, Lijuan; Wang, Biqin; Peng, Cheng; He, Chunmei; Tang, Minghai; Zhang, Fan; Hu, Jia; Li, Rui; Zhao, Xia; Wei, Yuquan

2008-11-01

A sensitive and reliable HPLC method with fluorescence detection based on the precolumn derivatization of glucosamine with 6-aminoquinolyl-N-hydroxylsuccinimidyl carbamate (AQC) was established for the quantitative determination of glucosamine in rat plasma. The plasma protein was precipitated by acetonitrile, followed by vortex mixing and centrifugation. The supernatant was divided into the organic layer and aqueous layer by adding sodium chloride, and then the aqueous layer was derivatized with AQC in 0.2 M borate buffer of pH 8.8 before the HPLC analysis. An amino acid analysis column (3.9 x 150 mm, 4 microm) was applied, with 140 mM sodium acetate buffer (pH = 5.25) and acetonitrile as mobile phase at a flow rate of 1 mL/min. A linear correlation coefficient of 0.9987 was calculated within the range of 0.1-30 microg/mL of the standard curve for glucosamine. The limit of detection was 30 ng/mL. The intra- and inter-day precisions (as RSD) were less than 7.38 and 12.72%, respectively. The intra- and inter-day accuracy ranged from 91.8 to 110.0%. Extraction recoveries of glucosamine in plasma were more than 90%. The validated method was successfully applied for the quantitative determination of glucosamine in rat plasma and evaluation for pharmacokinetic study of glucosamine. It was also possible to be applied for the quantitative determination of other compounds containing amino group in biological samples.

[Determination of icaritin in rat plasma by HPLC-MS/MS].

PubMed

Liu, Hai-Pei; Meng, Fan-Hua; Guo, Ji-Fen; Si, Duan-Yun; Zhu, Xiao-Wei; Zhao, Yi-Min

2009-10-01

The paper is to report the development of a high-performance liquid chromatographic/tandem mass spectrometry (HPLC-MS/MS) method for the determination of icaritin (ICT) in rat plasma. After precipitated with acetonitrile from the plasma, ICT was isolated chromatographically on a Dikma C18 column. The mobile phase consisted of acetonitrile-water-acetic acid (72 : 28 : 1.5, v/v/v). Electrospray ionization (ESI) source was applied and operated in the positive ion mode. Multiple reaction monitoring (MRM) mode with the transitions of m/z 387 --> m/z 313 and m/z 331 --> m/z 315 were used to quantify ICT and the internal standard, respectively. The linear calibration curve was obtained in the concentration range of 2.5-1,000 ng x mL(-1). The lower limit of quantification was 2.5 ng x mL(-1). The inter- and intra-day precision (RSD) were less than 9.63%, and the accuracy (relative error) was within +/-7.42%. The method was proved to be suitable for the pharmacokinetics of ICT, which offers advantages of high sensitivity and selectivity.

A biodegradable colorimetric film for rapid low-cost field determination of formaldehyde contamination by digital image colorimetry.

PubMed

Wongniramaikul, Worawit; Limsakul, Wadcharawadee; Choodum, Aree

2018-05-30

A biodegradable colorimetric film was fabricated on the lid of portable tube for in-tube formaldehyde detection. Based on the entrapment of colorimetric reagents within a thin film of tapioca starch, the yellow reaction product was observed with formaldehyde. Intensity of the blue channel from the digital image of yellow product showed a linear relationship in the range of 0-25 mg L -1 with low detection limit of 0.7 ± 0.1 mg L -1 . Inter-day precision of 0.61-3.10%RSD were obtained with less than 4.2% relative error from control samples. The developed method was applied for various food samples in Phuket and formaldehyde concentration range was non-detectable to 1.413 mg kg -1 . The quantified concentrations of formaldehyde in fish and squid samples provided relative errors of -7.7% and +10.8% compared to spectrophotometry. This low cost sensor (∼0.04 USD/test) with digital image colorimetry was thus an effective alternative for formaldehyde detection in food sample. Copyright © 2018 Elsevier Ltd. All rights reserved.

Determination of food colorants in a wide variety of food matrices by microemulsion electrokinetic capillary chromatography. Considerations on the found concentrations and regulated consumption limits.

PubMed

Bordagaray, Ane; Garcia-Arrona, Rosa; Vidal, Maider; Ostra, Miren

2018-10-01

Color additives are used widely by the food industry to confer a desirable appearance. Some of the most used colorants (Tartrazine (E102), Sunset Yellow (E110), Red Allure (E129) and Blue Brilliant (E133)) were determined in this study using microemulsion electrokinetic capillary chromatography (MEEKC). Regression coefficients were greater than 0.9981; intra- and inter-day precisions, in terms of percentage RSD, were less than 7.01% and 8.55%, respectively; recoveries were between 90 and 100% in most cases. LODs and LOQs ranged from 0.24 to 1.21 mg L -1 and from 0.80 to 4.03 mg L -1 , respectively. Moreover, MEEKC consumed less solvent than HPLC, making the analysis more environmentally friendly. The proposed method is suitable for the determination of colorants in a wide variety of foods. Results showed that consumers should be aware of colorants to avoid consumption exceeding recommended amounts. Copyright © 2018 Elsevier Ltd. All rights reserved.

Determination of Flavonol Aglycones in Ginkgo biloba Dietary Supplement Crude Materials and Finished Products by High-Performance Liquid Chromatography: Single Laboratory Validation

PubMed Central

Gray, Dean; LeVanseler, Kerri; Pan, Meide

2008-01-01

A single laboratory validation (SLV) was completed for a method to determine the flavonol aglycones quercetin, kaempferol, and isorhamnetin in Ginkgo biloba products. The method calculates total glycosides based on these aglycones formed following acid hydrolysis. Nine matrixes were chosen for the study, including crude leaf material, standardized dry powder extract, single and multiple entity finished products, and ethanol and glycerol tinctures. For the 9 matrixes evaluated as part of this SLV, the method appeared to be selective and specific, with no observed interferences. The simplified 60 min oven heating hydrolysis procedure was effective for each of the matrixes studied, with no apparent or consistent differences between 60, 75, and 90 min at 90°C. A Youden ruggedness trial testing 7 factors with the potential to affect quantitative results showed that 2 factors (volume hydrolyzed and test sample extraction/hydrolysis weight) were the most important parameters for control during sample preparation. The method performed well in terms of precision, with 4 matrixes tested in triplicate over a 3-day period showing an overall repeatability (relative standard deviation, RSD) of 2.3%. Analysis of variance testing at α = 0.05 showed no significant differences among the within- or between-group sources of variation, although comparisons of within-day (Sw), between-day (Sb), and total (St) precision showed that a majority of the standard deviation came from within-day determinations for all matrixes. Accuracy testing at 2 levels (approximately 30 and 90% of the determined concentrations in standardized dry powder extract) from 2 complex negative control matrixes showed an overall 96% recovery and RSD of 1.0% for the high spike, and 94% recovery and RSD of 2.5% for the low spike. HorRat scores were within the limits for performance acceptability, ranging from 0.4 to 1.3. Based on the performance results presented herein, it is recommended that this method progress to the collaborative laboratory trial. PMID:16001841

A sensitive UPLC-MS/MS method for simultaneous determination of eleven bioactive components of Tong-Xie-Yao-Fang decoction in rat biological matrices.

PubMed

Li, Tian-xue; Hu, Lang; Zhang, Meng-meng; Sun, Jian; Qiu, Yue; Rui, Jun-qian; Yang, Xing-hao

2014-01-01

There is a growing concern for the sensitive quantification of multiple components using advanced data acquisition method in herbal medicines (HMs). An improved and rugged UPLC-MS/MS method has been developed and validated for sensitive and rapid determination of multiply analytes from Tong-Xie-Yao-Fang (TXYF) decoction in three biological matrices (plasma/brain tissue/urine) using geniposide and formononetin as internal standards. After solid-phase extraction, chromatographic separation was performed on a C18 column using gradient elution. Quantifier and qualifier transitions were monitored using novel Triggered Dynamic multiple reaction monitoring (TdMRM) in the positive ionization mode. A significant peak symmetry and sensitivity improvement in the TdMRM mode was achieved as compared to conventional MRM. The reproducibility (RSD%) was ≤7.9% by applying TdMRM transition while the values were 6.8-20.6% for MRM. Excellent linear calibration curves were obtained under TdMRM transitions over the tested concentration ranges. Intra- and inter-day precisions (RSD%) were ≤14.2% and accuracies (RE%) ranged from -9.6% to 10.6%. The validation data of specificity, carryover, recovery, matrix effect and stability were within the required limits. The method was effectively applied to simultaneously detect and quantify 1 lactone, 2 monoterpene glucosides, 1 alkaloid, 5 flavonoids and 2 chromones in plasma, brain tissue and urine after oral administration of TXYF decoction. In conclusion, this new and reliable method is beneficial for quantification and confirmation assays of multiply components in complex biological samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of suppressor current intensity on the determination of glyphosate and aminomethylphosphonic acid by suppressed conductivity ion chromatography.

PubMed

Dimitrakopoulos, Ioannis K; Thomaidis, Nikolaos S; Megoulas, Nikolaos C; Koupparis, Michael A

2010-05-28

This paper presents the application of ion chromatography with electrolytic eluent generation and mobile phase suppression for the direct conductimetric detection of glyphosate and its degradation product aminomethylphosphonic acid (AMPA). The compounds were separated on a Dionex AS18 anion exchange column with a 12-40 mM KOH step gradient from 9 to 9.5 min. The effect of the suppressor current intensity on the electrostatic interaction of these amphoteric compounds with the suppressor cation exchange membranes was evaluated. A suppressor current gradient technique was proposed for the limitation of peak broadening and baseline noise, in order to improve method sensitivity and detectability. It was observed that residual sample carbonates co-eluted with AMPA when a large injection loop was installed for the low level determination of both compounds in natural waters. For this reason, glyphosate was isocratically eluted using 33 mM KOH in order to decrease analysis time within 10 min and a column clean up step using 100 mM KOH was used to ensure retention time reproducibility. The developed method was applied to the analysis of drinking and natural water and it was further successfully applied to orange samples with slight modifications. Instrumental LOD for glyphosate was 0.24 microg/L, while method LOD was 0.54 microg/L for spring waters and 0.01 mg/kg for oranges using a 1000 microL direct loop injection of the sample. Intra-day and inter-day precision (as %RSD) for water samples was 4.6% and 12% at a spiking level of 2 microg/L, and the recovery ranged from 64% to 88% depending on sample conductivity. For orange samples, the inter-day precision was 1.4% at a spiking level of 4.4 mg/kg, while overall recovery was 103%. The developed method is direct, fast, sensitive and relatively inexpensive, and could be used as an ideal fast screening tool for the monitoring of glyphosate residues in water and fruit samples. Copyright 2010 Elsevier B.V. All rights reserved.

Automated multisyringe stir bar sorptive extraction using robust montmorillonite/epoxy-coated stir bars.

PubMed

Ghani, Milad; Saraji, Mohammad; Maya, Fernando; Cerdà, Víctor

2016-05-06

Herein we present a simple, rapid and low cost strategy for the preparation of robust stir bar coatings based on the combination of montmorillonite with epoxy resin. The composite stir bar was implemented in a novel automated multisyringe stir bar sorptive extraction system (MS-SBSE), and applied to the extraction of four chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol) as model compounds, followed by high performance liquid chromatography-diode array detection. The different experimental parameters of the MS-SBSE, such as sample volume, selection of the desorption solvent, desorption volume, desorption time, sample solution pH, salt effect and extraction time were studied. Under the optimum conditions, the detection limits were between 0.02 and 0.34μgL(-1). Relative standard deviations (RSD) of the method for the analytes at 10μgL(-1) concentration level ranged from 3.5% to 4.1% (as intra-day RSD) and from 3.9% to 4.3% (as inter-day RSD at 50μgL(-1) concentration level). Batch-to-batch reproducibility for three different stir bars was 4.6-5.1%. The enrichment factors were between 30 and 49. In order to investigate the capability of the developed technique for real sample analysis, well water, wastewater and leachates from a solid waste treatment plant were satisfactorily analyzed. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of cooking on enrofloxacin residues in chicken tissue.

PubMed

Lolo, M; Pedreira, S; Miranda, J M; Vázquez, B I; Franco, C M; Cepeda, A; Fente, C

2006-10-01

The aim of this study was to determine the effect of different cooking processes (microwaving, roasting, boiling, grilling and frying) on naturally incurred enrofloxacin residues in chicken muscle. Enrofloxacin and its metabolite, ciprofloxacin, were analysed using a validated LC-MS method with limits of detection (LOD) and quantification (LOQ), respectively, of 2 and 5 ng g-1 quinolones in muscle samples. The method was shown to be linear over the range 5-500 ng g-1. Mean intra-day relative standard deviation (RSD) at a concentration of 50 ng g-1 (n = 6) was 6%; inter-day RSD was 12%. A recovery study demonstrated that 65-101%, of the drug and metabolite could be recovered from the tissue. The RSD with naturally incurred roasted chicken breast was 9.18% at a concentration of 11 +/- 1.01 ng g-1 (n = 6). In water, enrofloxacin remained stable for 3 h when heated at 100 degrees C. It was concluded that residue data from raw tissue are valid for estimation of consumer exposure to this drug, as well as the ADI calculations because cooking procedures did not affect enrofloxacin residues, which remained stable during heating. However, there was an apparent decrease in quinolone concentration in tissue because some was lost by exudation into the liquid used for cooking. Conversely, for a cooking procedure with water loss, there was an apparent increase in residue concentration.

Estimation of L-dopa from Mucuna pruriens LINN and formulations containing M. pruriens by HPTLC method.

PubMed

Modi, Ketan Pravinbhai; Patel, Natvarlal Manilal; Goyal, Ramesh Kishorilal

2008-03-01

A selective, precise, and accurate high-performance thin-layer chromatographic (HPTLC) method has been developed for the analysis of L-dopa in Mucuna pruriens seed extract and its formulations. The method involves densitometric evaluation of L-dopa after resolving it by HPTLC on silica gel plates with n-butanol-acetic acid-water (4.0+1.0+1.0, v/v) as the mobile phase. Densitometric analysis of L-dopa was carried out in the absorbance mode at 280 nm. The relationship between the concentration of L-dopa and corresponding peak areas was found to be linear in the range of 100 to 1200 ng/spot. The method was validated for precision (inter and intraday), repeatability, and accuracy. Mean recovery was 100.30%. The relative standard deviation (RSD) values of the precision were found to be in the range 0.64-1.52%. In conclusion, the proposed TLC method was found to be precise, specific and accurate and can be used for identification and quantitative determination of L-dopa in herbal extract and its formulations.

[Simultaneous determination of trichloroethylene and trichloroethanol in blood by liquid-liquid extraction-gas chromatography].

PubMed

Ye, H P; Shao, J; Tan, S W; Shan, X Y; Shi, Y P

2017-10-20

Objective: To establish a method for determing the trichloroethylene(TCE)and trichloroethanol(TCOH)in blood samples by liquid-liquid extraction-gas chromatography with electron capture detector. Methods: With this method,ether was used as extraction solvent and trichloromethane was used as an internal standard. The whole blood sample was extracted with ether, and dehydrated by anhydrous sodium sulfate. Then the analytes were separated on HP-5 capillary column(30m×0.32mm×0.15μm)and detected byECD.The retention time was for qualitative analysis and the internal standard was for quantitation. Results: The standard curves of TCE and TCOH showed significant linearity between 95.5μg/L-7640.0μg/L( r =0.9997)and 19.0μg/L-1520.0μg/L( r =0.9992). The average recovery was 95.5%-103.6%.The intra-day and inter-day precisions( RSD )were 2.5%-6.8%( n =6)and 1.6%-4.3%( n =6) respectively. The detect limit of TCE and TCOH were 2.10 μg/L and 0.56μg/L(S/N=3)respectively.The blood can be kept 7 days at-20℃ refrigerator without significantly loss. Conclusion: This method is proved to be simple,practical and highly sensitive. It can satisfy the request for the determination of blood samples of humans exposed to TCE.

Simultaneous analysis of herbicides pendimethalin, oxyfluorfen, imazethapyr and quizalofop-p-ethyl by LC-MS/MS and safety evaluation of their harvest time residues in peanut (Arachis hypogaea L.).

PubMed

Saha, Ajoy; Shabeer T P, Ahammed; Banerjee, Kaushik; Hingmire, Sandip; Bhaduri, Debarati; Jain, N K; Utture, Sagar

2015-07-01

This paper reports a simple and rapid method for simultaneous determination of the residues of selected herbicides viz. pendimethalin, oxyfluorfen, imazethapyr and quizalofop-p-ethyl in peanut by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A modified approach of the QuEChERS methodology was used to extract the herbicides from the peanut kernel without any clean-up. The method showed excellent linearity (r(2) > 0.99) with no significant matrix effect. Accuracy of the method in terms of average recoveries of all the four herbicides ranged between 69.4 -94.4 % at spiking levels of 0.05, 0.10 and 0.25 mg kg(-1) with intra-day and inter-day precision RSD (%) between 2.6-16.6 and 8.0-11.3, respectively. Limit of quantification (LOQs) was 5.0 μg kg(-1) for pendimethalin, imazethapyr and quizalofop-p-ethyl and 10.0 μg kg(-1) for oxyfluorfen. The expanded uncertainties were <11 % for determination of these herbicides in peanut. The proposed method was successfully applied for analysis of these herbicide residues in peanut samples harvested from the experimental field and the residues were below the detection level.

Determination of perchlorate from tea leaves using quaternary ammonium modified magnetic carboxyl-carbon nanotubes followed by liquid chromatography-tandem quadrupole mass spectrometry.

PubMed

Zhao, Yong-Gang; Zhang, Yun; Wang, Feng-Lian; Zhou, Jian; Zhao, Qi-Ming; Zeng, Xiu-Qiong; Hu, Mei-Qin; Jin, Mi-Cong; Zhu, Yan

2018-08-01

The novel quaternary ammonium modified magnetic carboxyl-carbon nanotubes (QA-Mag-CCNTs) have been synthesised and characterized. QA-Mag-CCNTs were applied in magnetic dispersive solid phase extraction (Mag-dSPE) for preconcentration of perchlorate from tea leaves prior to liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) analysis. The Mag-dSPE procedure for preconcentration of perchlorate succeed in overcoming the flaw (containing target analyte randomly) of commercially available SPE cartridge. Under optimal conditions, the results showed higher extraction efficiency of QA-Mag-CCNTs, with recoveries between 85.2% and 107%. And the satisfactory precision with inter-day and intra-day RSD values were lower than 8.0%. Furthermore, QA-Mag-CCNTs were evaluated for reuse up to 20 times. The limit of quantification (LOQ) for perchlorate was 8.21 ng kg -1 . The developed method was successfully applied in tea leaves for food-safety risk monitoring in Zhejiang province, China. The results showed the concentrations of perchlorate in 229 out of 240 collected samples were in the range of 0.082-988 μg kg -1 . It was confirmed that QA-Mag-CCNTs were highly effective materials used for preconcentration of perchlorate. Copyright © 2018 Elsevier B.V. All rights reserved.

2-Naphthalenthiol derivatization followed by dispersive liquid-liquid microextraction as an efficient and sensitive method for determination of acrylamide in bread and biscuit samples using high-performance liquid chromatography.

PubMed

Faraji, Mohammad; Hamdamali, Mohammadrezza; Aryanasab, Fezzeh; Shabanian, Meisam

2018-07-13

In this research, an ultrasonic-assisted extraction followed by 2-naphthalenthiol derivatization and dispersive liquid-liquid microextraction of acrylamide (AA) was developed as simple and sensitive sample preparation method for AA in bread and biscuit samples using high performance liquid chromatography. Influence of derivatization and microextraction parameters were evaluated and optimized. Results showed that the derivatization of AA leads to improve its hydrophobicity and chromatographic behavior. Under optimum conditions of derivatization and microextraction, the method yielded a linear calibration curve ranging from 10 to 1000 μg L -1 with a determination coefficient (R 2 ) of 0.9987. Limit of detection (LOD) and limit of quantification (LOQ) were 3.0 and 9.0 μg L -1 , respectively. Intra-day (n = 6) and inter-day (n = 3) precisions based on relative standard deviation percent (RSD%) for extraction and determination of AA at 50 and 500 μg L -1 levels were less than 9.0%. Finally, the performance of proposed method was investigated for determination of AA in some bread and biscuit samples, and satisfactory results were obtained (relative recovery ≥ 90%). Copyright © 2018. Published by Elsevier B.V.

Development and validation of a LC-ESI-MS/MS method for the determination of phenolic compounds in honeydew honeys with the diluted-and-shoot approach.

PubMed

Seraglio, Siluana Katia Tischer; Valese, Andressa Camargo; Daguer, Heitor; Bergamo, Greici; Azevedo, Mônia Stremel; Gonzaga, Luciano Valdemiro; Fett, Roseane; Costa, Ana Carolina Oliveira

2016-09-01

A simple, reproducible and sensitive method has been optimized and validated for simultaneous determination of 32 phenolic compounds in bracatinga (Mimosa scabrella Benth.) with the diluted-and-shoot approach, without the need of any additional clean-up steps. It has been based on high performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry and electrospray ionization (HPLC-ESI-MS/MS). The chromatography conditions were optimized, and due to the selectivity provided by MRM monitoring, LC separation required only 9min. The developed method was validated on the basis of Eurachem and European Commission Decision 2002/657/EC guidelines. Mean recoveries ranged from 70.4 to 110%. Intra-day and inter-day precision with RSD (relative standard deviations) from 0.14 to 18.9% and 0.34 to 20.0%, respectively were achieved. Limits of detection (LOD) and quantification (LOQ) ranged from 0.03 to 3.20μgL -1 and 0.20-12.8μgL -1 . Finally, the method was applied to samples and 20 phenolic compounds were quantified in all the samples analyzed, representing a contribution to the characterization and quantification of phenolic compounds from bracatinga (M. scabrella Bentham) honeydew honey. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simultaneous determination of three classes of antibiotics in the suspended solids of swine wastewater by ultrasonic extraction, solid-phase extraction and liquid chromatography-mass spectrometry.

PubMed

Pan, Xun; Qiang, Zhimin; Ben, Weiwei; Chen, Meixue

2011-01-01

This work describes a systematic approach to the development of a method for simultaneous determination of three classes of veterinary antibiotics in the suspended solids (SS) of swine wastewater, including five sulfonamides, three tetracyclines and one macrolide (tiamulin). The entire procedures for sample pretreatment, ultrasonic extraction (USE), solid-phase extraction (SPE), and liquid chromatography-mass spectrometry (LC-MS) quantification were examined and optimized. The recovery efficiencies were found to be 76%-104% for sulfonamides, 81%-112% for tetracyclines, and 51%-64% for tiamulin at three spiking levels. The intra-day and inter-day precisions, as expressed by the relative standard deviation (RSD), were below 17%. The method detection limits (MDLs) were between 0.14 and 7.14 microg/kg, depending on a specific antibiotic studied. The developed method was applied to field samples collected from three concentrated swine feeding plants located in Beijing, Shanghai and Shandong province of China. All the investigated antibiotics were detected in both SS and liquid phase of swine wastewater, with partition coefficients (logK(d)) ranging from 0.49 to 2.30. This study demonstrates that the SS can not be ignored when determining the concentrations of antibiotics in swine wastewater.

HPLC method for determination of SN-38 content and SN-38 entrapment efficiency in a novel liposome-based formulation, LE-SN38.

PubMed

Xuan, Tong; Zhang, J Allen; Ahmad, Imran

2006-05-03

A simple HPLC method was developed for quantification of SN-38, 7-ethyl-10-hydroxycamptothecin, in a novel liposome-based formulation (LE-SN38). The chromatographic separation was achieved on an Agilent Zorbax SB-C18 (4.6 mmx250 mm, 5 microm) analytical column using a mobile phase consisting of a mixture of NaH2PO4 (pH 3.1, 25 mM) and acetonitrile (50:50, v/v). SN-38 was detected at UV wavelength of 265 nm and quantitatively determined using an external calibration method. The limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.05 and 0.25 microg/mL, respectively. The individual spike recovery of SN-38 ranged from 100 to 101%. The percent of relative standard deviation (%R.S.D.) of intra-day and inter-day analyses were less than 1.6%. The method validation results confirmed that the method is specific, linear, accurate, precise, robust and sensitive for its intended use. The current method was successfully applied to the determination of SN-38 content and drug entrapment efficiency in liposome-based formulation, LE-SN38 during early stage formulation development.

A novel pretreatment method combining sealing technique with direct injection technique applied for improving biosafety.

PubMed

Wang, Xinyu; Gao, Jing-Lin; Du, Chaohui; An, Jing; Li, MengJiao; Ma, Haiyan; Zhang, Lina; Jiang, Ye

2017-01-01

People today have a stronger interest in the risk of biosafety in clinical bioanalysis. A safe, simple, effective method of preparation is needed urgently. To improve biosafety of clinical analysis, we used antiviral drugs of adefovir and tenofovir as model drugs and developed a safe pretreatment method combining sealing technique with direct injection technique. The inter- and intraday precision (RSD %) of the method were <4%, and the extraction recoveries ranged from 99.4 to 100.7%. Meanwhile, the results showed that standard solution could be used to prepare calibration curve instead of spiking plasma, acquiring more accuracy result. Compared with traditional methods, the novel method not only improved biosecurity of the pretreatment method significantly, but also achieved several advantages including higher precision, favorable sensitivity and satisfactory recovery. With these highly practical and desirable characteristics, the novel method may become a feasible platform in bioanalysis.

Colorimetric analyzer based on mobile phone camera for determination of available phosphorus in soil.

PubMed

Moonrungsee, Nuntaporn; Pencharee, Somkid; Jakmunee, Jaroon

2015-05-01

A field deployable colorimetric analyzer based on an "Android mobile phone" was developed for the determination of available phosphorus content in soil. An inexpensive mobile phone embedded with digital camera was used for taking photograph of the chemical solution under test. The method involved a reaction of the phosphorus (orthophosphate form), ammonium molybdate and potassium antimonyl tartrate to form phosphomolybdic acid which was reduced by ascorbic acid to produce the intense colored molybdenum blue. The software program was developed to use with the phone for recording and analyzing RGB color of the picture. A light tight box with LED light to control illumination was fabricated to improve precision and accuracy of the measurement. Under the optimum conditions, the calibration graph was created by measuring blue color intensity of a series of standard phosphorus solution (0.0-1.0mgPL(-1)), then, the calibration equation obtained was retained by the program for the analysis of sample solution. The results obtained from the proposed method agreed well with the spectrophotometric method, with a detection limit of 0.01mgPL(-1) and a sample throughput about 40h(-1) was achieved. The developed system provided good accuracy (RE<5%) and precision (RSD<2%, intra- and inter-day), fast and cheap analysis, and especially convenient to use in crop field for soil analysis of phosphorus nutrient. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous determination of isochamaejasmin, neochamaejasmin A and aphnoretinin rat plasma by UPLC-MS/MS and its application to a pharmacokinetic study of Stellera chamaejasme L. extract.

PubMed

Wang, Ludi; Yang, Wei; Wu, Siyang; Wang, Shuyao; Kang, Chen; Ma, Xiaoli; Li, Yingfei; Li, Chuan

2018-05-01

Isochamaejasmin, neochamaejasmin A and daphnoretin derived from Stellera chamaejasme L. are important because of their reported anticancer properties. In this study, a sensitive UPLC-MS/MS method for the determination of isochamaejasmin, neochamaejasmin A and daphnoretin in rat plasma was developed. The analyte and IS were separated on an Acquity UPLC HSS T3 column (100 × 2.1 mm, 1.8 μm) using gradient elution with the mobile phase of aqueous solution (methanol-water, 1:99, v/v, containing 1 mm formic acid) and organic solution (methanol-water, 99:1, v/v, containing 1 mm formic acid) at a flow rate of 0.3 mL/min. Multiple reaction monitoring mode with negative electrospray ionization interface was carried out to detect the components. The method was validated in terms of specificity, linearity, accuracy, precision, stability, etc. Excellent linear behavior was observed over the certain concentration ranges with the correlation coefficient values >0.99. Intra- and inter-day precisions (RSD) were <6.7% and accuracy (RE) ranged from -7.0 to 12.0%. The validated method was successfully applied to investigate the pharmacokinetics of three chemical ingredients after oral administration of S. chamaejasme L. extract to rats. Copyright © 2017 John Wiley & Sons, Ltd.

The effect of deep eutectic solvent on the pharmacokinetics of salvianolic acid B in rats and its acute toxicity test.

PubMed

Chen, Jue; Wang, Qi; Liu, Mengjun; Zhang, Liwei

2017-09-15

Deep eutectic solvent (DES), the benign green solvent with uniquely physical properties, has been widely applied in various fields. Our previous study indicated that DES could improve the stability and extraction efficiency of salvianolic acid B (SAB). In this work, with SAB as a model drug, the feasibility of DES as a drug carrier for oral preparation was investigated by evaluating the influence of DES on the pharmacokinetics of SAB and the toxicity of DES. Acute oral toxicity test illustrated that choline chloride-glycerol (ChCl-GL, molar ratio 1:2) was non-toxic with the median lethal dose of 7733mg/kg. To comparison the difference of pharmacokinetics between SAB dissolved in ChCl-GL (1:2) and in water, a rapid and sensitive ultra-performance liquid chromatography coupled with mass spectrum was established to determine SAB and its metabolites in rat plasma. The method validation was also tested for the specificity, linearity (r 2 >0.9980 over two orders of magnitude), precision (intra-day relative standard deviation (RSD)<2.73% and inter-day RSD<7.72%), extraction recovery (70.96-80.78%) and stability under three different situations. Compared to water, the pharmacokinetic parameters clarified that ChCl-GL (1:2) could promote the absorption of SAB, the peak concentration (C max ) of 0.308±0.020mg/L was slightly higher than 0.277±0.024mg/L (SAB dissolved in water), and the peak time (T max ) was significantly decreased from 30min (SAB dissolved in water) to 20min. There was no significant difference on the metabolites between SAB dissolved in ChCl-GL (1:2) and in water. This is the first report on the pharmacokinetic study of DES as a candidate of drug carrier, and the results provide a meaningful basis for the application of DES in pharmaceutical preparation. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination of eperisone hydrochloride and paracetamol in mouse plasma by high performance liquid chromatography-photodiode array detector.

PubMed

Locatelli, Marcello; Cifelli, Roberta; Di Legge, Cristina; Barbacane, Renato Carmine; Costa, Nicola; Fresta, Massimo; Celia, Christian; Capolupo, Carlo; Di Marzio, Luisa

2015-04-03

This paper reports the validation of a quantitative high performance liquid chromatography-photodiode array (HPLC-PDA) method for the simultaneous analysis, in mouse plasma, of eperisone hydrochloride and paracetamol by protein precipitation using zinc sulphate-methanol-acetonitrile. The analytes were resolved on a Gemini C18 column (4.6 mm × 250 mm; 5 μm particle size) using a gradient elution mode with a run time of 15 min, comprising re-equilibration, at 60°C (± 1°C). The method was validated over the concentration range from 0.5 to 25 μg/mL for eperisone hydrochloride and paracetamol, in mouse plasma. Ciprofloxacin was used as Internal Standard. Results from assay validations show that the method is selective, sensitive and robust. The limit of quantification of the method was 0.5 μg/mL for eperisone hydrochloride and paracetamol, and matrix-matched standard curves showed a good linearity, up to 25 μg/mL with correlation coefficients (r(2))≥ 0.9891. In the entire analytical range the intra and inter-day precision (RSD%) values were ≤ 1.15% and ≤ 1.46% for eperisone hydrochloride, and ≤ 0.35% and ≤ 1.65% for paracetamol. For both analytes the intra and inter-day trueness (bias%) values ranged, respectively, from -5.33% to 4.00% and from -11.4% to -4.00%. The method was successfully tested in pharmacokinetic studies after oral administration in mouse. Furthermore, the application of this method results in a significant reduction in terms of animal number, dosage, and improvement in speed, rate of analysis, and quality of pharmacokinetic parameters related to serial blood sampling. Copyright © 2015 Elsevier B.V. All rights reserved.

Sequential determination of fat- and water-soluble vitamins in Rhodiola imbricata root from trans-Himalaya with rapid resolution liquid chromatography/tandem mass spectrometry.

PubMed

Tayade, Amol B; Dhar, Priyanka; Kumar, Jatinder; Sharma, Manu; Chaurasia, Om P; Srivastava, Ravi B

2013-07-30

A rapid method was developed to determine both types of vitamins in Rhodiola imbricata root for the accurate quantification of free vitamin forms. Rapid resolution liquid chromatography/tandem mass spectrometry (RRLC-MS/MS) with electrospray ionization (ESI) source operating in multiple reactions monitoring (MRM) mode was optimized for the sequential analysis of nine water-soluble vitamins (B1, B2, two B3 vitamins, B5, B6, B7, B9, and B12) and six fat-soluble vitamins (A, E, D2, D3, K1, and K2). Both types of vitamins were separated by ion-suppression reversed-phase liquid chromatography with gradient elution within 30 min and detected in positive ion mode. Deviations in the intra- and inter-day precision were always below 0.6% and 0.3% for recoveries and retention time. Intra- and inter-day relative standard deviation (RSD) values of retention time for water- and fat-soluble vitamin were ranged between 0.02-0.20% and 0.01-0.15%, respectively. The mean recoveries were ranged between 88.95 and 107.07%. Sensitivity and specificity of this method allowed the limits of detection (LOD) and limits of quantitation (LOQ) of the analytes at ppb levels. The linear range was achieved for fat- and water-soluble vitamins at 100-1000 ppb and 10-100 ppb. Vitamin B-complex and vitamin E were detected as the principle vitamins in the root of this adaptogen which would be of great interest to develop novel foods from the Indian trans-Himalaya. Copyright © 2013 Elsevier B.V. All rights reserved.

[Pharmacokinetics and relative bioavailability of THC and THC-solid dispersion orally to mice at single dose].

PubMed

Liao, Li; Hua, Hua; Zhao, Jun-Ning; Luo, Heng; Yang, An-Dong

2014-03-01

To establish a fast sensitive, reproducible LC-MS/MS method to study pharmacokinetic properties of THC, and compare relative bioavailability of THC and its solid dispersion in mice. 200 mice were divided randomly into two groups, and administered orally with THC and THC-solid dispersion after fasting (calculate on THC:400 mg x kg(-1)), used HPLC-MS/MS method to determine the THC concentration of each period at the following times: baseline ( predose ), 15, 30, 45 min, 1, 1.5, 2, 3, 4, 6, 24 h after dosing. Calculating the pharmacokinetic parameters according to the C-t curv, and then use the Phoenix WinNonlin software for data analysis. The calibration curves were linear over the range 9.06-972 microg x L(-1) for THC (R2 = 0.999). The limit of detection (LOD) was 0.7 microg x L(-1), respectively. The average extraction recoveries for THC was above 75%, The methodology recoveries were between 79% and 108%. The intra-day and inter-day RSD were less than 13%, the stability test showed that the plasma samples was stable under different conditions (RSD < 15%). The precision, accuracy, recovery and applicability were found to be adequate for pharmacokinetic studies. Pharmacokinetic parameters of THC and THC-solid dispersion orally to mice shows as fllows: T(max), were 60 and 15 min, AUC(0-t) were 44 500.43 and 57 497.81 mg x L(-1) x min, AUC(0-infinity) were 51 226.00 and 68 031.48 mg x L(-1) x min, MRT(0-infinity) were 596.915 6, 661.747 7 min, CL(z)/F were 0.007 809 and 0.005 88 L x min(-1) x kg(-1). Compared with THC, the MRT and t1/2 of the THC-solid dispersion were all slightly extended, the t(max) was significantly reduced, AUC(0-24 h), AUC(0-infinity) and C(max) were all significantly higher, the relative bioavailability of THC-solid dispersion is 1.34 times of THC. The results of the experiment shows that the precision, accuracy, recovery and applicability were found to be adequate for the pharmacokinetic studies. After oral administration to mice, the relative bioavailability of THC-solid dispersion show significant improvement compared to THC.

Optimisation of an analytical method and results from the inter-laboratory comparison of the migration of regulated substances from food packaging into the new mandatory European Union simulant for dry foodstuffs.

PubMed

Jakubowska, Natalia; Beldì, Giorgia; Peychès Bach, Aurélie; Simoneau, Catherine

2014-01-01

This paper presents the outcome of the development, optimisation and validation at European Union level of an analytical method for using poly(2,6-diphenyl phenylene oxide--PPPO), which is stipulated in Regulation (EU) No. 10/2011, as food simulant E for testing specific migration from plastics into dry foodstuffs. Two methods for fortifying respectively PPPO and a low-density polyethylene (LDPE) film with surrogate substances that are relevant to food contact were developed. A protocol for cleaning the PPPO and an efficient analytical method were developed for the quantification of butylhydroxytoluene (BHT), benzophenone (BP), diisobutylphthalate (DiBP), bis(2-ethylhexyl) adipate (DEHA) and 1,2-cyclohexanedicarboxylic acid, diisononyl ester (DINCH) from PPPO. A protocol for a migration test from plastics using small migration cells was also developed. The method was validated by an inter-laboratory comparison (ILC) with 16 national reference laboratories for food contact materials in the European Union. This allowed for the first time data to be obtained on the precision and laboratory performance of both migration and quantification. The results showed that the validation ILC was successful even when taking into account the complexity of the exercise. The results showed that the method performance was 7-9% repeatability standard deviation (rSD) for most substances (regardless of concentration), with 12% rSD for the high level of BHT and for DiBP at very low levels. The reproducibility standard deviation results for the 16 European Union laboratories were in the range of 20-30% for the quantification from PPPO (for the three levels of concentrations of the five substances) and 15-40% from migration experiments from the fortified plastic at 60°C for 10 days and subsequent quantification. Considering the lack of data previously available in the literature, this work has demonstrated that the validation of a method is possible both for migration from a film and for quantification into a corresponding simulant for specific migration.

Theoretically guided analytical method development and validation for the estimation of rifampicin in a mixture of isoniazid and pyrazinamide by UV spectrophotometer

NASA Astrophysics Data System (ADS)

Khan, Mohammad F.; Rita, Shamima A.; Kayser, Md. Shahidulla; Islam, Md. Shariful; Asad, Sharmeen; Bin Rashid, Ridwan; Bari, Md. Abdul; Rahman, Muhammed M.; Al Aman, D. A. Anwar; Setu, Nurul I.; Banoo, Rebecca; Rashid, Mohammad A.

2017-04-01

A simple, rapid, economic, accurate and precise method for the estimation of rifampicin in a mixture of isoniazid and pyrazinamide by UV spectrophotometeric technique (guided by the theoretical investigation of physicochemical properties) was developed and validated. Theoretical investigations revealed that isoniazid and pyrazinamide both were freely soluble in water and slightly soluble in ethyl acetate whereas rifampicin was practically insoluble in water but freely soluble in ethyl acetate. This indicates that ethyl acetate is an effective solvent for the extraction of rifampicin from a water mixture of isoniazid and pyrazinamide. Computational study indicated that pH range of 6.0-8.0 would favor the extraction of rifampicin. Rifampicin is separated from isoniazid and pyrazinamide at pH 7.4 ± 0.1 by extracting with ethyl acetate. The ethyl acetate was then analyzed at λmax of 344.0 nm. The developed method was validated for linearity, accuracy and precision according to ICH guidelines. The proposed method exhibited good linearity over the concentration range of 2.5 - 35.0 µg/mL. The intraday and inter-day precision in terms of % RSD ranged from 1.09 - 1.70% and 1.63 - 2.99%, respectively. The accuracy (in terms of recovery) of the method varied from of 96.7 ± 0.9 to 101.1 ± 0.4%. The LOD and LOQ were found to be 0.83 and 2.52 µg/mL, respectively. In addition, the developed method was successfully applied to assay rifampicin combination (isoniazid and pyrazinamide) brands available in Bangladesh.

Trace analysis of glyphosate in water by capillary electrophoresis on a chip with high sample volume loadability.

PubMed

Horčičiak, Michal; Masár, Marián; Bodor, Róbert; Danč, Ladislav; Bel, Peter

2012-03-01

A new method for the determination of trace glyphosate (GLYP), non-selective pesticide, by CZE with online ITP pre-treatment of drinking waters on a column-coupling (CC) chip has been developed. CC chip was equipped with two injection channels of 0.9 and 9.9 μL volumes, two separation channels of 9.3 μL total volume and a pair of conductivity detectors. A very effective ITP sample clean-up performed in the first channel at low pH (3.2) was introduced for quick CZE resolution and detection of GLYP carried out at higher pH (6.1) in the second channel on the CC chip. The LOD for GLYP was estimated at 2.5 μg/L (15 nmol/L) using a 9.9 |mL volume of the injection channel. ITP-CZE analyses of model and real samples have provided very favorable intra-day (0.1-1.2% RSD) and inter-day (2.9% RSD) repeatabilities of the migration time for GLYP while 0.2-6.9% RSD values were typical for the peak area data. Recoveries of GLYP in spiked drinking water varied in the range of 99-109%. A minimum pre-treatment of drinking water (degassing and dilution) and a short analysis time (ca. 10 min) were distinctive features of ITP-CZE determinations of GLYP on the CC chip with high sample volume loaded, as well. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a hydrophilic interaction liquid chromatography-mass spectrometry method for detection and quantification of urea thermal decomposition by-products in emission from diesel engine employing selective catalytic reduction technology.

PubMed

Yassine, Mahmoud M; Dabek-Zlotorzynska, Ewa; Celo, Valbona

2012-03-16

The use of urea based selective catalytic reduction (SCR) technology for the reduction of NOx from the exhaust of diesel-powered vehicles has the potential to emit at least six thermal decomposition by-products, ammonia, and unreacted urea from the tailpipe. These compounds may include: biuret, dicyandiamine, cyanuric acid, ammelide, ammeline and melamine. In the present study, a simple, sensitive and reliable hydrophilic interaction liquid chromatography (HILIC)-electrospray ionization (ESI)/mass spectrometry (MS) method without complex sample pre-treatment was developed for identification and determination of urea decomposition by-products in diesel exhaust. Gradient separation was performed on a SeQuant ZIC-HILIC column with a highly polar zwitterionic stationary phase, and using a mobile phase consisting of acetonitrile (eluent A) and 15 mM ammonium formate (pH 6; eluent B). Detection and quantification were performed using a quadrupole ESI/MS operated simultaneously in negative and positive mode. With 10 μL injection volume, LODs for all target analytes were in the range of 0.2-3 μg/L. The method showed a good inter-day precision of retention time (RSD<0.5%) and peak area (RSD<3%). Satisfactory extraction recoveries from spiked blanks ranged between 96 and 98%. Analyses of samples collected during transient chassis dynamometer tests of a bus engine equipped with a diesel particulate filter (DPF) and urea based SCR technology showed the presence of five target analytes with cyanuric acid and ammelide the most abundant compounds in the exhaust. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Development of a Fourier transform infrared spectroscopy coupled to UV-Visible analysis technique for aminosides and glycopeptides quantitation in antibiotic locks.

PubMed

Sayet, G; Sinegre, M; Ben Reguiga, M

2014-01-01

Antibiotic Lock technique maintains catheters' sterility in high-risk patients with long-term parenteral nutrition. In our institution, vancomycin, teicoplanin, amikacin and gentamicin locks are prepared in the pharmaceutical department. In order to insure patient safety and to comply to regulatory requirements, antibiotic locks are submitted to qualitative and quantitative assays prior to their release. The aim of this study was to develop an alternative quantitation technique for each of these 4 antibiotics, using a Fourier transform infrared (FTIR) coupled to UV-Visible spectroscopy and to compare results to HPLC or Immunochemistry assays. Prevalidation studies permitted to assess spectroscopic conditions used for antibiotic locks quantitation: FTIR/UV combinations were used for amikacin (1091-1115cm(-1) and 208-224nm), vancomycin (1222-1240cm(-1) and 276-280nm), and teicoplanin (1226-1230cm(-1) and 278-282nm). Gentamicin was quantified with FTIR only (1045-1169cm(-1) and 2715-2850cm(-1)) due to interferences in UV domain of parabens, preservatives present in the commercial brand used to prepare locks. For all AL, the method was linear (R(2)=0.996 to 0.999), accurate, repeatable (intraday RSD%: from 2.9 to 7.1% and inter-days RSD%: 2.9 to 5.1%) and precise. Compared to the reference methods, the FTIR/UV method appeared tightly correlated (Pearson factor: 97.4 to 99.9%) and did not show significant difference in recovery determinations. We developed a new simple reliable analysis technique for antibiotics quantitation in locks using an original association of FTIR and UV analysis, allowing a short time analysis to identify and quantify the studied antibiotics. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Thermally condensed humic acids onto silica as SPE for effective enrichment of glucocorticoids from environmental waters followed by HPLC-HESI-MS/MS.

PubMed

Speltini, Andrea; Merlo, Francesca; Maraschi, Federica; Sturini, Michela; Contini, Matteo; Calisi, Nicola; Profumo, Antonella

2018-03-09

Pristine humic acids (HAs) were thermally condensed onto silica microparticles by a one-pot, inexpensive and green preparation route obtaining a mixed-mode sorbent (HA-C@silica) with good sorption affinity for glucocorticoids (GCs). The carbon-based material, characterized by various techniques, was indeed applied as the sorbent for fixed-bed solid-phase extraction of eight GCs from river water and wastewater treatment plant effluent, spiked at different concentration levels in the range 1-400 ng L -1 . After sample extraction, the target analytes were simultaneously and quantitatively eluted in a single fraction of methanol, achieving enrichment factor 4000 and 1000 in river water and wastewater effluent, respectively. Full recovery for all compounds, was gained in the real matrices studied (80-125% in river water, 79-126% in wastewater effluent), with inter-day precision showing relative standard deviations (RSD) below 15% and 18% (n = 3), for river and wastewater effluent, correspondingly. The high enrichment factors coupled with high-performance liquid chromatography tandem mass spectrometry quantification (MRM mode) provided method quantification limits of 0.009-0.48 ng L -1 in river water and 0.06-3 ng L -1 in wastewater effluent and, at the same time, secure identification of the selected drugs. As also evidenced by comparison with literature, HA-C@silica proved to be a valid alternative to the current commercial sorbents, in terms of extraction capability, enrichment factor, ease of preparation and cost. The batch-to-batch reproducibility was assessed by recovery tests on three independently prepared HA-C@silica powders (RSD lower than 7%). Copyright © 2018 Elsevier B.V. All rights reserved.

Optimization of solid-phase extraction and liquid chromatography-tandem mass spectrometry for simultaneous determination of capilliposide B and its active metabolite in rat urine and feces: Overcoming nonspecific binding.

PubMed

Cheng, Zhongzhe; Zhou, Xing; Li, Wenyi; Hu, Bingying; Zhang, Yang; Xu, Yong; Zhang, Lin; Jiang, Hongliang

2016-11-30

Capilliposide B, a novel oleanane triterpenoid saponin isolated from Lysimachia capillipes Hemsl, showed significant anti-tumor activities in recent studies. To characterize the excretion of Capilliposide B, a reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous determination of Capilliposide B and its active metabolite, Capilliposide A in rat urine and feces. Sample preparation using a solid-phase extraction procedure was optimized by acidification of samples at various degrees, providing extensive sample clean-up with a high extraction recovery. In addition, rat urinary samples were pretreated with CHAPS, an anti-adsorptive agent, for overcoming nonspecific analytes adsorption during sample storage and process. The method validation was conducted over the curve range of 10.0-5000ng/ml for both analytes. The intra- and inter-day precision and accuracy of the QC samples showed ≤11.0% RSD and -10.4-12.8% relative error. The method was successfully applied to an excretion study of Capilliposide B following intravenous administration. Copyright © 2016 Elsevier B.V. All rights reserved.

In vivo study on the neurotransmitters and their metabolites change in depressive disorder rat plasma by ultra high performance liquid chromatography coupled to tandem mass spectrometry.

PubMed

Zhao, Longshan; Zheng, Shuning; Su, Guangyue; Lu, Xiumei; Yang, Jingyu; Xiong, Zhili; Wu, Chunfu

2015-04-15

A sensitive and versatile, ultra-high performance, liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method coupled to pre-column derivatization for the simultaneous determination of 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), dopamine (DA), norepinephrine (NE), homovanillic acid (HVA), γ-aminobutyric acid (GABA) and glutamic acid (Glu) was developed and validated in rat plasma. The analytes were dansylated under strong alkaline conditions after protein precipitation extraction, which were analyzed on a BEH C18 column using a gradient elution. The lower limit of quantification (LLOQ) values for 5-HT, 5-HIAA, DA, NE, HVA, GABA and Glu were 1.00, 1.00, 0.991, 0.992, 1.02, 1000, and 5030 pmol/mL, respectively. Good linearity was obtained (r > 0.99) and the intra- and inter-day precisions of the method (relative standard deviation, RSD%) were lower than 12%. The method was novel, sensitive and specific which can provide an alternative method for the quantification of neurotransmitters and their metabolites in plasma samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Fast Simultaneous Determination of 13 Nucleosides and Nucleobases in Cordyceps sinensis by UHPLC-ESI-MS/MS.

PubMed

Zong, Shi-Yu; Han, Han; Wang, Bing; Li, Ning; Dong, Tina Ting-Xia; Zhang, Tong; Tsim, Karl W K

2015-12-04

A reliable ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS) method for the fast simultaneous determination of 13 nucleosides and nucleobases in Cordyceps sinensis (C. sinensis) with 2-chloroadenosine as internal standard was developed and validated. Samples were ultrasonically extracted in an ice bath thrice, and the optimum analyte separation was performed on an ACQUITY UPLC(TM) HSS C18 column (100 mm × 2.1 mm, 1.8 μm) with gradient elution. All targeted analytes were separated in 5.5 min. Furthermore, all calibration curves showed good linear regression (r > 0.9970) within the test ranges, and the limits of quantitation and detection of the 13 analytes were less than 150 and 75 ng/mL, respectively. The relative standard deviations (RSDs) of intra- and inter-day precisions were <6.23%. Recoveries of the quantified analytes ranged within 85.3%-117.3%, with RSD < 6.18%. The developed UHPLC-ESI-MS/MS method was successfully applied to determine nucleosides and nucleobases in 11 batches of C. sinensis samples from different regions in China. The range for the total content in the analyzed samples was 1329-2057 µg/g.

Study on pharmacokinetics of 3,4-divanillyltetrahydrofuran in rats by ultra-fast liquid chromatography/tandem mass spectrometry.

PubMed

Shan, Chen-Xiao; Cui, Xiao-Bing; Yu, Sheng; Chai, Chuan; Wen, Hong-Mei; Wang, Xin-Zhi; Sun, Xue

2016-01-01

3,4-Divanillyltetrahydrofuran is the main active ingredient of nettle root which can increase steroid hormones in the bloodstream for many of bodybuilders. To better understand its pharmacological activities, we need to determine its pharmacokinetic profiles. In this study, a rapid and sensitive ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method has been developed for the determination of 3,4-divanillyltetrahydrofuran in the plasma of rats. Chromatographic separation was performed on a C18 column at 40°C, with a gradient elution consisting of methanol and water containing 0.3% (v/v) formic acid at a flow rate of 0.8mL/min. The detection was performed using an electrospray triple-quadrupole MS/MS via positive ion multiple reaction monitoring mode. The lower limits-of-quantification determined were 0.5ng/mL. The intra- and inter-day precision (RSD%) was found to be within 15% and the accuracy (RE%) ranged from -4.0% to 7.0%. This simple yet sensitive method was fully validated and could be successfully applied to the study on pharmacokinetics of 3, 4-divanillyltetrahydrofuran. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of Organothiophosphate Insecticides in Environmental Water Samples by a Very Simple and Sensitive Spectrofluorimetric Method.

PubMed

Bavili Tabrizi, Ahad; Abdollahi, Ali

2015-10-01

A simple, rapid and sensitive spectrofluorimetric method was developed for the determination of di-syston, ethion and phorate in environmental water samples. The procedure is based on the oxidation of these pesticides with cerium (IV) to produce cerium (III), and its fluorescence was monitored at 368 ± 3 nm after excitation at 257 ± 3 nm. The variables effecting oxidation of each pesticide were studied and optimized. Under the experimental conditions used, the calibration graphs were linear over the range 0.2-15, 0.1-13, 0.1-13 ng mL(-1) for di-syston, ethion and phorate, respectively. The limit of detection and quantification were in the range 0.034-0.096 and 0.112-0.316 ng mL(-1), respectively. Intra- and inter-day assay precisions, expressed as the relative standard deviation (RSD), were lower than 5.2 % and 6.7 %, respectively. Good recoveries in the range 86 %-108 % were obtained for spiked water samples. The proposed method was applied to the determination of studied pesticides in environmental water samples.

Evaluation of layered double hydroxide/graphene hybrid as a sorbent in membrane-protected stir-bar supported micro-solid-phase extraction for determination of organochlorine pesticides in urine samples.

PubMed

Sajid, Muhammad; Basheer, Chanbasha; Daud, Muhammad; Alsharaa, Abdulnaser

2017-03-17

In this work, the potential of layered double hydroxide/graphene (LDH-G) hybrid as a sorbent for extraction and preconcentration of fifteen organochlorine pesticides (OCPs) in urine samples was evaluated. The LDH-G hybrid was synthesized by co-precipitation method and it was then characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The sorbent was then employed in membrane-protected stir-bar supported micro-solid-phase extraction (SB-μ-SPE) of OCPs in urine samples. This extraction approach is highly suitable for the samples representing matrix complexity such as urine because the sorbent is effectively protected inside the membrane. The extracted samples were analyzed by gas chromatography mass spectrometry. The factors that affect the performance of SB-μ-SPE were suitably optimized. This method demonstrated good linearity with coefficients of determination up to 0.9996. The limits of detection ranged between 0.22 and 1.38ngmL -1 . The RSD values for intra and inter-day precision were also in a satisfactory range (2.7-9.5%). Copyright © 2017 Elsevier B.V. All rights reserved.

Liquid chromatographic method for the simultaneous determination of cefalexin and trimethoprim in dog plasma and application to the pharmacokinetic studies of a coformulated preparation.

PubMed

Qi, Meiling; Wang, Peng; Sun, Ping; Liu, Xia

2006-03-07

A liquid chromatographic method is described for the simultaneous determination of cefalexin and trimethoprim in dog plasma. A simple protein precipitation procedure was adopted for the sample preparation with satisfactory extraction recoveries for both analytes. Chromatographic separation of the analytes was achieved on a C(18) column using a mixture of 2 mol/l formate buffer (pH 3.5), methanol and acetonitrile (22:7:7, v/v/v) containing a 0.002 mol/l sodium dodecyl sulfate as mobile phase and detection was performed at 240 nm. The linearity was obtained over the concentration ranges of 1.0-100.0 microg/ml for cefalexin and 0.5-50.0 microg/ml for trimethoprim. For each level of QC samples including the lower limit of quantification, both inter- and intra-day precisions (R.S.D.) were < or =14.0% for cefalexin and < or =11.4% for trimethoprim, and accuracy (RE) was -1.4% for cefalexin and -3.0% for trimethoprim. The present LC method was successfully applied to the pharmacokinetic studies of coformulated cefalexin dispersible tablets after oral administration to beagle dogs.

Rapid and sensitive quantitation of the antiproliferative agent mitoguazone in small volumes of plasma by high-performance liquid chromatography with ultraviolet detection.

PubMed

Cheng, Ching-Ling; Lin, E Gin; Chou, Chen-Hsi

2003-08-15

Mitoguazone is an antiproliferative agent used in chemotherapy. This study describes a simple and sensitive high-performance liquid chromatographic method for the determination of mitoguazone in 100 microl of plasma. Samples were deproteinized with 100 microl of a solution of internal standard (amiloride, 10 microg/ml) in acetonitrile. An aliquot of the supernatant was injected onto the column. HPLC separation was achieved on a silica column with the mobile phase of methanol-50 mM potassium phosphate buffer (pH 3)-triethylamine (80:20:0.3, v/v), at a flow-rate of 1 ml/min. The eluent was detected at 320 nm. The retention time was about 5.5 min for amiloride and 12 min for mitoguazone. No endogenous substances were found to interfere. Calibration curves were linear from 0.25 to 50 microg/ml. The absolute recoveries of mitoguazone and amiloride were both greater than 84%. The limit of quantitation was 0.25 microg/ml. The intra- and inter-day precision (expressed as RSD) was 5.8%, or less, and the accuracy was 94.7% of the nominal concentration. The method is suitable in pharmacokinetic investigation and monitoring mitoguazone concentration.

Validation of a fast and accurate chromatographic method for detailed quantification of vitamin E in green leafy vegetables.

PubMed

Cruz, Rebeca; Casal, Susana

2013-11-15

Vitamin E analysis in green vegetables is performed by an array of different methods, making it difficult to compare published data or choosing the adequate one for a particular sample. Aiming to achieve a consistent method with wide applicability, the current study reports the development and validation of a fast micro-method for quantification of vitamin E in green leafy vegetables. The methodology uses solid-liquid extraction based on the Folch method, with tocol as internal standard, and normal-phase HPLC with fluorescence detection. A large linear working range was confirmed, being highly reproducible, with inter-day precisions below 5% (RSD). Method sensitivity was established (below 0.02 μg/g fresh weight), and accuracy was assessed by recovery tests (>96%). The method was tested in different green leafy vegetables, evidencing diverse tocochromanol profiles, with variable ratios and amounts of α- and γ-tocopherol, and other minor compounds. The methodology is adequate for routine analyses, with a reduced chromatographic run (<7 min) and organic solvent consumption, and requires only standard chromatographic equipment available in most laboratories. Copyright © 2013 Elsevier Ltd. All rights reserved.

Liquid chromatographic tandem mass spectrometric assay for quantification of 97/78 and its metabolite 97/63: a promising trioxane antimalarial in monkey plasma.

PubMed

Singh, R P; Sabarinath, S; Gautam, N; Gupta, R C; Singh, S K

2009-07-15

The present manuscript describes development and validation of LC-MS/MS assay for the simultaneous quantitation of 97/78 and its active in-vivo metabolite 97/63 in monkey plasma using alpha-arteether as internal standard (IS). The method involves a single step protein precipitation using acetonitrile as extraction method. The analytes were separated on a Columbus C(18) (50 mm x 2 mm i.d., 5 microm particle size) column by isocratic elution with acetonitrile:ammonium acetate buffer (pH 4, 10 mM) (80:20 v/v) at a flow rate of 0.45 mL/min, and analyzed by mass spectrometry in multiple reaction-monitoring (MRM) positive ion mode. The chromatographic run time was 4.0 min and the weighted (1/x(2)) calibration curves were linear over a range of 1.56-200 ng/mL. The method was linear for both the analytes with correlation coefficients >0.995. The intra-day and inter-day accuracy (% bias) and precisions (% RSD) of the assay were less than 6.27%. Both analytes were stable after three freeze-thaw cycles (% deviation <8.2) and also for 30 days in plasma (% deviation <6.7). The absolute recoveries of 97/78, 97/63 and internal standard (IS), from spiked plasma samples were >90%. The validated assay method, described here, was successfully applied to the pharmacokinetic study of 97/78 and its active in-vivo metabolite 97/63 in Rhesus monkeys.

Hybrid molecularly imprinted polymers synthesized with 3-aminopropyltriethoxysilane-methacrylic acid monomer for miniaturized solid-phase extraction: A new and economical sample preparation strategy for determination of acyclovir in urine.

PubMed

Yan, Hongyuan; Wang, Mingyu; Han, Yehong; Qiao, Fengxia; Row, Kyung Ho

2014-06-13

The miniaturized molecularly imprinted solid-phase extraction (mini-MISPE) coupled with high-performance liquid chromatography was proposed for the determination of acyclovir in urine. 1.5-mL tapered plastic centrifuge tube filled with hybrid molecularly imprinted polymers (HMIPs) was used as the cartridge of mini-MISPE, and the HMIPs synthesized with 3-aminopropyltriethoxy silane-methacrylic acid as monomer exhibited good recognition and selectivity for acyclovir. Under the optimized condition, good linear calibration was obtained in a range of 0.5-15μgmL(-1) with the correlation coefficient of 0.9994, and the recoveries at three spiked levels were 91.6-103.3% in urine with the relative standard deviation (RSD) of ≤3.5%. Excellent intra-day and inter-day repeatability were achieved with RSD of ≤2.6% and 4.0% in three different concentrations. This method combined the advantages of HMIPs and mini-MISPE, and it could become an alternative tool for analyzing the residues of acyclovir in complex urine matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

Evaluating the precision of passive sampling methods using ...

EPA Pesticide Factsheets

To assess these models, four different thicknesses of low-density polyethylene (LDPE) passive samplers were co-deployed for 28 days in the water column at three sites in New Bedford Harbor, MA, USA. Each sampler was pre-loaded with six PCB performance reference compounds (PRCs) to assess equilibrium status, such that the percent of PRC lost would range depending on PRC and LDPE thickness. These data allow subsequent Cfree comparisons to be made in two ways: (1) comparing Cfree derived from one thickness using different models and (2) comparing Cfree derived from the same model using different thicknesses of LDPE. Following the deployments, the percent of PRC lost ranged from 0-100%. As expected, fractional equilibrium decreased with increasing PRC molecular weight as well as sampler thickness. Overall, a total of 27 PCBs (log KOW ranging from 5.07 – 8.09) were measured at Cfree concentrations varying from 0.05 pg/L (PCB 206) to about 200 ng/L (PCB 28) on a single LDPE sampler. Relative standard deviations (RSDs) for total PCB measurements using the same thickness and varying model types range from 0.04-12% and increased with sampler thickness. Total PCB RSD for measurements using the same model and varying thickness ranged from: 6 – 30%. No RSD trends between models were observed but RSD did increase as Cfree decreased. These findings indicate that existing models yield precise and reproducible results when using LDPE and PRCs to measure Cfree. This work in

Evolution in the design of a low sheath-flow interface for CE-MS and application to biological samples.

PubMed

González-Ruiz, Víctor; Codesido, Santiago; Rudaz, Serge; Schappler, Julie

2018-03-01

Although several interfaces for CE-MS hyphenation are commercially available, the development of new versatile, simple and yet efficient and sensitive alternatives remains an important field of research. In a previous work, a simple low sheath-flow interface was developed from inexpensive parts. This interface features a design easy to build, maintain, and adapt to particular needs. The present work introduces an improved design of the previous interface. By reducing the diameter of the separation capillary and the emitter, a smaller Taylor cone is spontaneously formed, minimizing the zone dispersion while the analytes go through the interface and leading to less peak broadening associated to the ESI process. Numerical modeling allowed studying the mixing and diffusion processes taking place in the Taylor cone. The analytical performance of this new interface was tested with pharmaceutically relevant molecules and endogenous metabolites. The interface was eventually applied to the analysis of neural cell culture samples, allowing the identification of a panel of neurotransmission-related molecules. An excellent migration time repeatability was obtained (intra-day RSD <0.5% for most compounds, and <3.0% for inter-day precision). Most metabolites showed S/N ratios >10 with an injected volume of 6.7 nL of biological extract. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sol-gel electrospinning preparation of hybrid carbon silica nanofibers for extracting organophosphorus pesticides prior to analyzing them by gas chromatography-ion mobility spectrometry.

PubMed

Jafari, Mohammad T; Saraji, Mohammad; Kermani, Mansoure

2018-07-13

Carbon-silica hybrid nanofibers as high performance coatings for solid-phase microextraction fibers were used for analyzing some pesticides by using gas chromatography-corona discharge ion mobility spectrometry. To that end, the fibers were prepared by carbonizing sol-gel based on electrospun polyacrylonitrile and tetraethyl orthosilicate nanofibers as carbon and silica precursors, respectively. Different parameters affecting the electrospinning and the extraction processes including spinning distance, voltage, feeding rate, stirring rate, salt concentration, temperature and extraction time were optimized by response surface methodology. The method involved deionized water samples spiked with pesticides at different concentration levels. The calibration curves were linear in the ranges of 0.1-20 and 0.05-20 μg L -1 with determination coefficients (R 2 ) of 0.9976 and 0.9928 for malathion and chlorpyrifos, respectively. The limits of detection of 0.032 and 0.019 μg L -1 and the limits of quantification of 0.1 and 0.05 μg L -1 were found for malathion and chlorpyrifos, respectively. Acceptable reproducibility values were obtained with relative standard deviations (RSD, n = 3) lower than 6 and 15%, for intra-day and inter-day precision, respectively. Finally, the relative recoveries of the proposed method were calculated in the range of 80-111% for real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Sequential cloud-point extraction for toxicological screening analysis of medicaments in human plasma by high pressure liquid chromatography with diode array detector.

PubMed

Madej, Katarzyna; Persona, Karolina; Wandas, Monika; Gomółka, Ewa

2013-10-18

A complex extraction system with the use of cloud-point extraction technique (CPE) was developed for sequential isolation of basic and acidic/neutral medicaments from human plasma/serum, screened by HPLC/DAD method. Eight model drugs (paracetamol, promazine, chlorpromazine, amitriptyline, salicyclic acid, opipramol, alprazolam and carbamazepine) were chosen for the study of optimal CPE conditions. The CPE technique consists in partition of an aqueous sample with addition of a surfactant into two phases: micelle-rich phase with the isolated compounds and water phase containing a surfactant below the critical micellar concentration, mainly under influence of temperature change. The proposed extraction system consists of two chief steps: isolation of basic compounds (from pH 12) and then isolation of acidic/neutral compounds (from pH 6) using surfactant Triton X-114 as the extraction medium. Extraction recovery varied from 25.2 to 107.9% with intra-day and inter-day precision (RSD %) ranged 0.88-1087 and 5.32-17.96, respectively. The limits of detection for the studied medicaments at λ 254nm corresponded to therapeutic or low toxic plasma concentration levels. Usefulness of the proposed CPE-HPLC/DAD method for toxicological drug screening was tested via its application to analysis of two serum samples taken from patients suspected of drug overdosing. Published by Elsevier B.V.

Liquid chromatography-tandem mass spectrometry method for determination of panel of neurotransmitters in cerebrospinal fluid from the rat model for tauopathy.

PubMed

Kovac, Andrej; Somikova, Zuzana; Zilka, Norbert; Novak, Michal

2014-02-01

Alzheimer's disease (AD) is still being recognized today as an unmet medical need. Currently, there is no cure and early preclinical diagnostic assay available for AD. Therefore much attention is now being directed at the development of novel methods for quantitative determination of AD biomarkers in the cerebrospinal fluid (CSF). Here, we describe the liquid chromatography-tandem mass spectrometry method for determination of 5-hydroxytryptamine (SER), 5-hydroxyindoleacetic acid (5-HIAA), homovanilic acid (HVA), noradrenaline (NADR), adrenaline (ADR), dopamine (DA), glutamic acid (Glu), γ-aminobutyric acid (GABA), 3,4-dihydroxyphenylacetic acid (DOPAC) and histamine (HIS) in cerebrospinal fluid (CSF) from the rat model for human tauopathy. The benzoyl chloride was used as pre-column derivatization reagents. Neurotransmitters and metabolites were analysed on ultra performance liquid chromatography (UPLC) on C18 column in combination with tandem mass spectrometry. The method is simple, highly sensitive and showed excellent linearity with regression coefficients higher than 0.99. The accuracy was in a range of 93-113% for all analytes. The inter-day precision (n=5 days), expressed as %RSD, was in a range 2-10% for all analytes. Using this method we detected significant changes of CSF levels of two important neurotransmitters/metabolites, ADR and 5-HIAA, which correlates with progression of neurodegeneration in our animal model. © 2013 Published by Elsevier B.V.

Distribution study of tryptanthrin in rat tissues by HPLC and its relationship with meridian tropism of indigo naturalis in traditional Chinese medicine.

PubMed

Zhang, Ning; Hua, Ying; Wang, Cuiling; Sun, Yanni; Wang, Zheng; Liu, Zhulan; Liu, Jianli

2014-12-01

The aim of the present study is to characterize the distribution of tryptanthrin (TRYP) in rat tissues following oral administration at a dose of 100 mg/kg and its relationship with meridian tropism (MT) of indigo naturalis (IN) in traditional Chinese medicine (TCM). For quantitative analysis in biological samples, a sensitive, inexpensive and accurate high-performance liquid chromatographic method was developed and validated with 2-hydroxy acetophenone as internal standard, a Shimadzu C18 column and water-acetonitrile (55:45, v/v) as mobile phase. Acceptable intra-day and inter-day precision at high, medium and low concentration was acquired with RSD ranging from 0.87 to 5.22% and from 1.25 to 6.47%, respectively. Good assay and extraction recoveries were obtained with a single and relatively fast step to precipitate protein. The extraction recovery of TRYP ranged from 87.5 to 94.5 %. TRYP concentration was highest in the liver and remained for a much longer time than in other tissues. It could also be detected in kidney, lung, heart and spleen, but not in brain under the experimental conditions. The results confirmed the traditional knowledge of TCM that MT of IN belongs to the liver meridians and demonstrated that TRYP is one of the active constituents of the MT of IN. Copyright © 2014 John Wiley & Sons, Ltd.

Simultaneous determination of ginsenoside Rb1, naringin, ginsenoside Rb2 and oridonin in rat plasma by LC-MS/MS and its application to a pharmacokinetic study after oral administration of Weifuchun tablet.

PubMed

Jin, Yiran; Tian, Tingting; Ma, Yinghua; Xu, Huijun; Du, Yingfeng

2015-09-01

A sensitive, specific and rapid liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for analysis of ginsenoside Rb1, naringin, ginsenoside Rb2 and oridonin in rat plasma using sulfamethoxazole as an internal standard (IS). Separation was conducted out on an Agilent Eclipse XDB C18 column with liner gradient elution using acetonitrile (A) and 0.1% aqueous acetic acid (B). A tandem mass spectrometric detection was conducted using multiple reaction monitoring (MRM) via an electrospray ionization (ESI) source. A novel multi-determination-periods program was executed to achieve a higher sensitivity by setting three scanning periods. All analytes exhibited good linearity within the concentration range (r>0.9973). The lower limits of quantitation (LLOQ) of ginsenoside Rb1, naringin, ginsenoside Rb2 and oridonin were 2.64, 4.32, 2.32 and 1.56ng/mL, respectively. Intra-day and inter-day precisions of the investigated components exhibited an RSD within 8.3%, and the accuracy (RE) ranged from -8.6% to 6.0% at all quality control levels. The developed method was successfully applied to a pharmacokinetic study of ginsenoside Rb1, naringin, ginsenoside Rb2 and oridonin in rats after oral administration of a Weifuchun tablet. Copyright © 2015 Elsevier B.V. All rights reserved.

An improved HPLC-DAD method for quantitative comparisons of triterpenes in Ganoderma lucidum and its five related species originating from Vietnam.

PubMed

Ha, Do Thi; Loan, Le Thi; Hung, Tran Manh; Han, Le Vu Ngoc; Khoi, Nguyen Minh; Dung, Le Viet; Min, Byung Sun; Nguyen, Nguyen Phuong Dai

2015-01-09

An HPLC-DAD method for the quality control of wild and cultivated Ganoderma lucidum (Linhzhi) and related species samples was developed and validated. The quantitative determination of G. lucidum and its related species using 14 triterpene constituents, including nine ganoderma acids (compounds 4-12), four alcohols (compounds 13-16), and one sterol (ergosterol, 17) were reported. The standard curves were linear over the concentration range of 7.5-180 µg/mL. The LOD and LOQ values for the analyses varied from 0.34 to 1.41 µg/mL and from 1.01 to 4.23 µg/mL, respectively. The percentage recovery of each reference compound was found to be from 97.09% to 100.79%, and the RSD (%) was less than 2.35%. The precision and accuracy ranged from 0.81%-3.20% and 95.38%-102.19% for intra-day, and from 0.43%-3.67% and 96.63%-103.09% for inter-day, respectively. The study disclosed in detail significant differences between the quantities of analyzed compounds in different samples. The total triterpenes in wild Linhzhi samples were significantly higher than in cultivated ones. The total constituent contents of the five related Linhzhi samples were considerably lower than that in the G. lucidum specimens, except for G. australe as its constituent content outweighed wild Linhzhi's content by 4:1.

Pharmacokinetic study of indocyanine Green after intravenous administration by UPLC-MS/MS.

PubMed

Chen, Yu; Chen, Dongxin; Hu, Wenhao; Lin, Guanyang; Huang, Shiyong

2015-01-01

Indocyanine Green is widely used in medical diagnosis and to evaluate liver function and other regional blood flows in clinical application or animal experiments. In this work, a sensitive and selective ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determination of Indocyanine Green in rat plasma was developed and validated. After addition of rutin as an internal standard (IS), protein precipitation by acetonitrile-methanol (9:1, v/v) was used to prepare samples. Chromatographic separation was achieved on a UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 μm) with 0.1% formic acid and acetonitrile as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reactions monitoring (MRM) mode was used for quantification using target fragment ions m/z 753.4→330.2 for Indocyanine Green, and m/z 611.1→303.1 for IS. Calibration plots were linear throughout the range 20-5000 ng/mL for Indocyanine Green in rat plasma. Mean recoveries of Indocyanine Green in rat plasma ranged from 79.5% to 85.4%. RSD of intra-day and inter-day precision were both < 12%. The accuracy of the method was between 95.9% and 113.9%. The method was successfully applied to pharmacokinetic study of Indocyanine Green after intravenous administration.

Pharmacokinetic study of indocyanine Green after intravenous administration by UPLC-MS/MS

PubMed Central

Chen, Yu; Chen, Dongxin; Hu, Wenhao; Lin, Guanyang; Huang, Shiyong

2015-01-01

Indocyanine Green is widely used in medical diagnosis and to evaluate liver function and other regional blood flows in clinical application or animal experiments. In this work, a sensitive and selective ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determination of Indocyanine Green in rat plasma was developed and validated. After addition of rutin as an internal standard (IS), protein precipitation by acetonitrile-methanol (9:1, v/v) was used to prepare samples. Chromatographic separation was achieved on a UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 μm) with 0.1% formic acid and acetonitrile as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reactions monitoring (MRM) mode was used for quantification using target fragment ions m/z 753.4→330.2 for Indocyanine Green, and m/z 611.1→303.1 for IS. Calibration plots were linear throughout the range 20-5000 ng/mL for Indocyanine Green in rat plasma. Mean recoveries of Indocyanine Green in rat plasma ranged from 79.5% to 85.4%. RSD of intra-day and inter-day precision were both < 12%. The accuracy of the method was between 95.9% and 113.9%. The method was successfully applied to pharmacokinetic study of Indocyanine Green after intravenous administration. PMID:26629038

Determination of multicomponent contents in Calculus bovis by ultra-performance liquid chromatography-evaporative light scattering detection and its application for quality control.

PubMed

Kong, Weijun; Jin, Cheng; Xiao, Xiaohe; Zhao, Yanling; Liu, Wei; Li, Zulun; Zhang, Ping

2010-06-01

A fast ultra-performance liquid chromatography-evaporative light scattering detection (UPLC-ELSD) method was established for simultaneous quantification of seven components in natural Calculus bovis (C. bovis) and its substitutes or spurious breeds. On a Waters Acquity UPLC BEH C(18) column, seven analytes were efficiently separated using 0.2% aqueous formic acid-acetonitrile as the mobile phase in a gradient program. The evaporator tube temperature of ELSD was set at 100 degrees C with the nebulizing gas flow-rate of 1.9 L/min. The results showed that this established UPLC-ELSD method was validated to be sensitive, precise and accurate with the LODs of seven analytes at 2-11 ng, and the overall intra-day and inter-day variations less than 3.0%. The recovery of the method was in the range of 97.8-101.6%, with RSD less than 3.0%. Further results of PCA on the contents of seven investigated analytes suggested that compounds of cholic acid, deoxycholic acid and chenodeoxycholic acid or cholesterol should be added as chemical markers to UPLC analysis of C. bovis samples for quality control and to discriminate natural C. bovis sample and its substitutes or some spurious breeds, then normalize the use of natural C. bovis and ensure its clinical efficacy.

A validated bioanalytical HPLC method for pharmacokinetic evaluation of 2-deoxyglucose in human plasma

PubMed Central

Gounder, Murugesan K.; Lin, Hongxia; Stein, Mark; Goodin, Susan; Bertino, Joseph R.; Kong, Ah-Ng Tony; DiPaola, Robert S.

2015-01-01

2-deoxyglucose (2-DG), an analog of glucose, is widely used to interfere with the glycolysis in tumor cells and studied as a therapeutic approach in clinical trials. To evaluate the pharmacokinetics of 2-DG, we describe the development and validation of a sensitive HPLC fluorescent method for the quantitation of 2-DG in plasma. Plasma samples were deproteinized with methanol and the supernatant was dried at 45°C. The residues were dissolved in methanolic sodium acetate/boric acid solution. 2-DG and other monosaccharides were derivatized to 2-aminobenzoic acid derivatives in a single step in the presence of sodium cyanoborohydride at 80°C for 45min. The analytes were separated on a YMC ODS C18 reversed-phase column using gradient elution. The excitation and emission wavelengths were set at 360 and 425nm. The 2-DG calibration curves were linear over the range of 0.63 to 300μg/mL with the limit of detection of 0.5μg/mL. The assay provided satisfactory intra-day and inter-day precision with RSD less than 9.8% and the accuracy ranged from 86.8% to 110.0%. The HPLC method is reproducible and suitable for the quantitation of 2-DG in plasma. The method was successfully applied to characterize the pharmacokinetics profile of 2-DG in patients with advanced solid tumors. PMID:21932382

[Detection of rifampicin concentration in cerebrospinal fluid by online enrichment and restricted-access media coupled with high-performance liquid chromatography].

PubMed

Yang, Xiaoping; Zhang, Xiaohui; Huang, Yanping; Wang, Rong; Xia, Hua; Li, Wenbin; Guo, YouMin

2015-11-01

To establish a method for detecting rifampicin in human cerebrospinal fluid (CSF) with restricted access media coupled with high-performance liquid chromatography that allows online direct sample injection and enrichment. We used the column of restricted access media as the pre-treatment column and a C18 column as the analytical column. The mobile phase of pre-treatment column was water-methanol (95:5,V/V) and the flow rate was 1 mL/min; the mobile phase of the analytical column was methanol-acetonitrile-10 mmol/L ammonuium acetate (volume ratio of 60:5:35). The detection wavelength was 254 nm and the column temperature was set at 25 degrees celsius;. For an injection volume of 100 µL, the peak area of rifampicin was 5.33 times that for an injection volume of 20 µL, and the limit of detection was effectively improved. The calibration curve showed an excellent linear relationship (r=0.9997) between rifampicin concentrations and peak areas within the concentration range of 0.25 to 8 µg/mL in CSF. The limits of detection and quantification was 0.07 µg/mL and 0.25 µg/mL, respecetively, with intra-day and inter-day assay precisions and relative standard deviation (RSD%) all below 5%. The recoveries of rifampicin at 3 blank spiked levels (low, medium, and high) ranged from 87.69% to 102.11%. In patients taking oral rifampicin at the dose of 10 mg/kg, the average rifampicin concentration was 0.29 in the CSF at 2 h after medication. The method we established is simple and fast for detecting rifampicin in CSF and allows direct online injection and enrichment with good detection precisions and accuracies.

Tetracycline residues in royal jelly and honey by liquid chromatography tandem mass spectrometry: validation study according to Commission Decision 2002/657/EC.

PubMed

Giannetti, L; Longo, F; Buiarelli, F; Russo, M V; Neri, B

2010-09-01

A specific, sensitive and robust liquid chromatography tandem mass spectrometry method for determining oxytetracycline, tetracycline, chlortetracycline and doxycycline in royal jelly and honey samples is presented. Extraction of drug residues was performed by ammonium acetate buffer as extractant followed by a clean-up with metal chelate affinity chromatography and solid-phase extraction. Tetracycline analysis was performed using liquid chromatography-electrospray ionisation-tandem mass spectrometry. The presented method is the first validated for royal jelly and in accordance with the requirements set by Commission Decision 2002/657/EC. Recoveries of the methods, calculated spiking the samples at 5.0, 10.0, 20.0 and 30.0 μg kg(-1), were 79% to 90% for honey and 77% to 90% for royal jelly. The intra-day precision (RSD) ranged between 8.1% and 15.0% for honey and from 9.1% to 16.3% for royal jelly, while inter-day precision values were from 10.2% to 17.6% and from 10.6% to 18.4% respectively for honey and royal jelly. Linearity for the four analytes was calculated from 5.0 to 50.0 μg kg(-1). The decision limits (CCα) ranged from 6.2 to 6.4 μg kg(-1) and from 6.1 to 6.5 μg kg(-1) for honey and royal jelly, respectively. Detection capabilities values (CCβ) ranged between 7.2 and 7.7 μg kg(-1) and from 7.3 to 7.9 μg kg(-1) respectively for honey and royal jelly. The developed method is currently in use for confirmation of the official control analysis of honey and royal jelly samples.

Liquid chromatography mass spectrometry determination of perfluoroalkyl acids in environmental solid extracts after phospholipid removal and on-line turbulent flow chromatography purification.

PubMed

Mazzoni, M; Polesello, S; Rusconi, M; Valsecchi, S

2016-07-01

An on-line TFC (Turbulent Flow Chromatography) clean up procedures coupled with UHPLC-MS/MS (Ultra High Performance Liquid Chromatography Mass Spectrometry) multi-residue method was developed for the simultaneous determination of 8 perfluroalkyl carboxylic acids (PFCA, from 5 to 12 carbon atoms) and 3 perfluoroalkyl sulfonic acids (PFSA, from 4 to 8 carbon atoms) in environmental solid matrices. Fast sample preparation procedure was based on a sonication-assisted extraction with acetonitrile. Phospholipids in biological samples were fully removed by an off-line SPE purification before injection, using HybridSPE(®) Phospholipid Ultra cartridges. The development of the on-line TFC clean-up procedure regarded the choice of the stationary phase, the optimization of the mobile phase composition, flow rate and injected volume. The validation of the optimized method included the evaluation of matrix effects, accuracy and reproducibility. Signal suppression in the analysis of fortified extracts ranged from 1 to 60%, and this problem was overcome by using isotopic dilution. Since no certified reference materials were available for PFAS in these matrices, accuracy was evaluated by recoveries on spiked clam samples which were 98-133% for PFCAs and 40-60% for PFSAs. MLDs and MLQs ranged from 0.03 to 0.3ngg(-1) wet weight and from 0.1 to 0.9ngg(-1) wet weight respectively. Repeatability (intra-day precision) and reproducibility (inter-day precision) showed RSD from 3 to 13% and from 4 to 27% respectively. Validated on-line TFC/UHPLC-MS/MS method has been applied for the determination of perfluoroalkyl acids in different solid matrices (sediment, fish, bivalves and bird yolk). Copyright © 2016 Elsevier B.V. All rights reserved.

Applicability of the DPPH assay for evaluating the antioxidant capacity of food additives - inter-laboratory evaluation study -.

PubMed

Shimamura, Tomoko; Sumikura, Yoshihiro; Yamazaki, Takeshi; Tada, Atsuko; Kashiwagi, Takehiro; Ishikawa, Hiroya; Matsui, Toshiro; Sugimoto, Naoki; Akiyama, Hiroshi; Ukeda, Hiroyuki

2014-01-01

An inter-laboratory evaluation study was conducted in order to evaluate the antioxidant capacity of food additives by using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Four antioxidants used as existing food additives (i.e., tea extract, grape seed extract, enju extract, and d-α-tocopherol) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) were used as analytical samples, and 14 laboratories participated in this study. The repeatability relative standard deviation (RSD(r)) of the IC50 of Trolox, four antioxidants, and the Trolox equivalent antioxidant capacity (TEAC) were 1.8-2.2%, 2.2-2.9%, and 2.1-2.5%, respectively. Thus, the proposed DPPH assay showed good performance within the same laboratory. The reproducibility relative standard deviation (RSD(R)) of IC50 of Trolox, four antioxidants, and TEAC were 4.0-7.9%, 6.0-11%, and 3.7-9.3%, respectively. The RSD(R)/RSD(r) values of TEAC were lower than, or nearly equal to, those of IC50 of the four antioxidants, suggesting that the use of TEAC was effective for reducing the variance among the laboratories. These results showed that the proposed DPPH assay could be used as a standard method to evaluate the antioxidant capacity of food additives.

Re-establishment of Anxiety in Stress-Sensitized Mice Is Caused by Monocyte Trafficking from the Spleen to the Brain

PubMed Central

Wohleb, Eric S.; McKim, Daniel B.; Shea, Daniel T.; Powell, Nicole D.; Tarr, Andrew J.; Sheridan, John F.; Godbout, Jonathan P.

2014-01-01

Background Persistent anxiety-like symptoms may have an inflammatory-related pathophysiology. Our previous work using repeated social defeat (RSD) in mice showed that recruitment of peripheral myeloid cells to the brain is required for the development of anxiety. Here, we aimed to determine if 1) RSD promotes prolonged anxiety through redistribution of myeloid cells and 2) prior exposure to RSD sensitizes the neuroimmune axis to secondary subthreshold stress. Methods Mice were subjected to RSD and several immune and behavioral parameters were determined 0.5, 8, or 24 days later. In follow-up studies, control and RSD mice were subjected to subthreshold stress at 24 days. Results Repeated social defeat-induced macrophage recruitment to the brain corresponded with development and maintenance of anxiety-like behavior 8 days after RSD, but neither remained at 24 days. Nonetheless, social avoidance and an elevated neuroinflammatory profile were maintained at 24 days. Subthreshold social defeat in RSD-sensitized mice increased peripheral macrophage trafficking to the brain that promoted re-establishment of anxiety. Moreover, subthreshold social defeat increased social avoidance in RSD-sensitized mice compared with naïve mice. Stress-induced monocyte trafficking was linked to redistribution of myeloid progenitor cells in the spleen. Splenectomy before subthreshold stress attenuated macrophage recruitment to the brain and prevented anxiety-like behavior in RSD-sensitized mice. Conclusions These data indicate that monocyte trafficking from the spleen to the brain contributes re-establishment of anxiety in stress-sensitized mice. These findings show that neuroinflammatory mechanisms promote mood disturbances following stress-sensitization and outline novel neuroimmune interactions that underlie recurring anxiety disorders such as posttraumatic stress disorder. PMID:24439304

Re-establishment of anxiety in stress-sensitized mice is caused by monocyte trafficking from the spleen to the brain.

PubMed

Wohleb, Eric S; McKim, Daniel B; Shea, Daniel T; Powell, Nicole D; Tarr, Andrew J; Sheridan, John F; Godbout, Jonathan P

2014-06-15

Persistent anxiety-like symptoms may have an inflammatory-related pathophysiology. Our previous work using repeated social defeat (RSD) in mice showed that recruitment of peripheral myeloid cells to the brain is required for the development of anxiety. Here, we aimed to determine if 1) RSD promotes prolonged anxiety through redistribution of myeloid cells and 2) prior exposure to RSD sensitizes the neuroimmune axis to secondary subthreshold stress. Mice were subjected to RSD and several immune and behavioral parameters were determined .5, 8, or 24 days later. In follow-up studies, control and RSD mice were subjected to subthreshold stress at 24 days. Repeated social defeat-induced macrophage recruitment to the brain corresponded with development and maintenance of anxiety-like behavior 8 days after RSD, but neither remained at 24 days. Nonetheless, social avoidance and an elevated neuroinflammatory profile were maintained at 24 days. Subthreshold social defeat in RSD-sensitized mice increased peripheral macrophage trafficking to the brain that promoted re-establishment of anxiety. Moreover, subthreshold social defeat increased social avoidance in RSD-sensitized mice compared with naïve mice. Stress-induced monocyte trafficking was linked to redistribution of myeloid progenitor cells in the spleen. Splenectomy before subthreshold stress attenuated macrophage recruitment to the brain and prevented anxiety-like behavior in RSD-sensitized mice. These data indicate that monocyte trafficking from the spleen to the brain contributes re-establishment of anxiety in stress-sensitized mice. These findings show that neuroinflammatory mechanisms promote mood disturbances following stress-sensitization and outline novel neuroimmune interactions that underlie recurring anxiety disorders such as posttraumatic stress disorder. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Simultaneous determination of kolliphor HS15 and miglyol 812 in microemulsion formulation by ultra-high performance liquid chromatography coupled with nano quantity analyte detector.

PubMed

Zhang, Honggen; Wang, Zhenyu; Liu, Oscar

2016-02-01

A novel method for simultaneous determination of kolliphor HS15 and miglyol 812 in microemulsion formulation was developed using ultra-high performance liquid chromatography coupled with a nano quantitation analytical detector (UHPLC-NQAD). All components in kolliphor HS15 and miglyol 812 were well separated on an Acquity BEH C 18 column. Mobile phase A was 0.1% trifluoroacetic acid (TFA) in water and mobile phase B was acetonitrile. A gradient elution sequence was programed initially with 60% organic solvent, slowly increased to 100% within 8 min. The flow rate was 0.7 mL/min. Good linearity ( r >0.95) was obtained in the range of 27.6-1381.1 μg/mL for polyoxyl 15 hydroxystearate in kolliphor HS15, 0.8-202.0 μg/mL for caprylic acid triglyceride and 2.7-221.9 μg/mL for capric acid triglyceride in miglyol 812. The relative standard deviations (RSD) ranged from 0.6% to 1.7% for intra-day precision and from 0.4% to 2.7% for inter-day precision. The overall recoveries (accuracy) were 99.7%-101.4% for polyoxyl 15 hydroxystearate in kolliphor HS15, 96.7%-99.6% for caprylic acid triglyceride, and 94.1%-103.3% for capric acid triglyceride in miglyol 812. Quantification limits (QL) were determined as 27.6 μg/mL for polyoxyl 15 hydroxystearate in kolliphor HS15, 0.8 μg/mL for caprylic acid triglyceride, and 2.7 μg/mL for capric acid triglyceride in miglyol 812. No interferences were observed in the retention time ranges of kolliphor HS15 and miglyol 812. The method was validated in terms of specificity, linearity, precision, accuracy, QL, and robustness. The proposed method has been applied to microemulsion formulation analyses with good recoveries (82.2%-103.4%).

Pharmacokinetic, bioavailability and tissue distribution study of MP3950, a new gastroprokinetic candidate compound, in rat using UPLC-MS/MS.

PubMed

Zhao, Yu; Zhao, Min; Jiang, Qi; Qin, Feng; Wang, Chengying; Xiong, Zhili; Wang, Shaojie; He, Zhonggui; Guo, Xingjie; Zhao, Longshan

2018-06-02

MP3950 is being developed as a gastroprokinetic candidate compound. To illustrate the pharmacokinetic profiles, absolute bioavailability after intravenous administration and oral administration with MP3950 as well as tissue distribution in vivo, an UPLC-MS/MS approach which was rapid and selective was developed to determine MP3950 in plasma and tissue of rat. Sample pre-treatment of plasma sample was one-step protein precipitation. 0.1% formic acid containing 5 mmol/L ammonium acetate-methanol(55/45,v/v) was used for isocratic elution on a Waters ACQUITY UPLC® BEH C18 (50 mm × 2.1 mm, 1.7 μm) to achieve the separation. The analysis was performed in MRM mode via positive ESI mode. LLOQ of the method was 10 ng/mL, and the linearity up to 10,000 ng/mL. The intra-day precision (relative standard deviation, RSD) was 4.0-9.0% and the inter-day precision was 4.2-10.6%. The accuracy (relative error, RE) was -1.2-2.4%. Tissue samples were collected from the brain, heart, liver, spleen, lung, kidney, stomach, duodenum, small intestine, large intestine, appendix and skeletal muscle. The same liquid chromatographic and mass spectrometric conditions were used, and it's proven that this method was feasible to analyze the MP3950 in tissues with good precision and accuracy over the range from 10 to 5000 ng·mL -1 . It was found that the concentration of MP3950 is higher in digestive system. The tissue distribution, pharmacokinetic and bioavailability of MP3950 in rats were carried out by the method for the first time, which can provide enough information for the further development and investigation of MP3950. Copyright © 2018. Published by Elsevier B.V.

[Cloning and characterization of a novel rat gene RSD-7 differentially expressed in testis].

PubMed

Zhang, Xiao-dong; Gou, Da-wei; Miao, Shi-ying; Zhang, Jian-chao; Zong, Shu-dong; Wang, Lin-fang

2003-06-01

To isolate and identify the differentially expressed genes in spermatogenesis for the understanding molecular mechanism of spermatogenesis. Screening of the cDNA library, Northern blot, expression and purification in E. coli with GST expression system, immunocytochemical staining of testis sections were used. (1) A cDNA fragment designated as RSD-7 was isolated from rat testis cDNA library. It was 1,238 bp in length, coding a protein of 232 amino acids with the GenBank accession number AF315467. The encoding protein of RSD-7 cDNA had a Ubiquitin-like domain. (2) Northern blot indicated that RSD-7 was uniquely expressed in rat testis, and in the testis RSD-7 emerged on the 30th postnatal day and expressed until 120th postnatal day. (3) Expression and purification of RSD-7 protein in E. coli with GST expression system and were used to obtain anti-RSD-7 antibody. (4) Immunolocalization of RSD-7 in rat testis revealed that it is expressed only in Sertoli cells. Transcription pattern of RSD-7 and localization of RSD-7 protein in testis have been made, which established the base for the functional study of RSD-7.

Selectivity of hexaphenylbenzene-based hydrocarbon stationary phase with propeller-like conformation for aromatic and aliphatic isomers.

PubMed

Yang, Yinhui; Chang, Zhengfeng; Yang, Xiaohong; Qi, Meiling; Wang, Jinliang

2018-08-03

Herein we report a propeller-like hexaphenylbenzene-based hydrocarbon material (denoted as BT) as the stationary phase for capillary gas chromatography (GC). The statically-coated BT capillary column showed a high column efficiency of 4340 plates m -1 and weak polarity. Owing to its unique conformation, π-electron toroidal delocalization and intrinsic microporosity, the BT stationary phase exhibited interesting selectivity for aromatic compounds over alkanes. Compared with the graphene (G) column, the BT column showed much prolonged retention and high selectivity for aromatic isomers, especially methylnaphthalenes, dimethylnaphthalenes and phenanthrene/anthracene, mainly because of its propeller-like conformation with rich intercalation effects. Moreover, it exhibited good column repeatability (intra-day, inter-day) and reproducibility (between-column) with RSD values on the retention times less than 0.08% for intra-day, 0.32% for inter-day and 3.8% for between-column, respectively. Also, it showed good potential for determination of minor isomer impurities in real samples. To the best of our knowledge, this work presents the first example of employing an neat aromatic hydrocarbon material as the GC stationary phase with high selectivity for analytes of a wide ranging polarity. Copyright © 2018 Elsevier B.V. All rights reserved.

Sympathetic Release of Splenic Monocytes Promotes Recurring Anxiety Following Repeated Social Defeat.

PubMed

McKim, Daniel B; Patterson, Jenna M; Wohleb, Eric S; Jarrett, Brant L; Reader, Brenda F; Godbout, Jonathan P; Sheridan, John F

2016-05-15

Neuroinflammatory signaling may contribute to the pathophysiology of chronic anxiety disorders. Previous work showed that repeated social defeat (RSD) in mice promoted stress-sensitization that was characterized by the recurrence of anxiety following subthreshold stress 24 days after RSD. Furthermore, splenectomy following RSD prevented the recurrence of anxiety in stress-sensitized mice. We hypothesize that the spleen of RSD-exposed mice became a reservoir of primed monocytes that were released following neuroendocrine activation by subthreshold stress. Mice were subjected to subthreshold stress (i.e., single cycle of social defeat) 24 days after RSD, and immune and behavioral measures were taken. Subthreshold stress 24 days after RSD re-established anxiety-like behavior that was associated with egress of Ly6C(hi) monocytes from the spleen. Moreover, splenectomy before RSD blocked monocyte trafficking to the brain and prevented anxiety-like behavior following subthreshold stress. Splenectomy, however, had no effect on monocyte accumulation or anxiety when determined 14 hours after RSD. In addition, splenocytes cultured 24 days after RSD exhibited a primed inflammatory phenotype. Peripheral sympathetic inhibition before subthreshold stress blocked monocyte trafficking from the spleen to the brain and prevented the re-establishment of anxiety in RSD-sensitized mice. Last, β-adrenergic antagonism also prevented splenic monocyte egress after acute stress. The spleen served as a unique reservoir of primed monocytes that were readily released following sympathetic activation by subthreshold stress that promoted the re-establishment of anxiety. Collectively, the long-term storage of primed monocytes in the spleen may have a profound influence on recurring anxiety disorders. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Sympathetic Release of Splenic Monocytes Promotes Recurring Anxiety Following Repeated Social Defeat

PubMed Central

McKim, Daniel B.; Patterson, Jenna M.; Wohleb, Eric S.; Jarrett, Brant; Reader, Brenda; Godbout, Jonathan P.; Sheridan, John F.

2015-01-01

Background Neuroinflammatory signaling may contribute to the pathophysiology of chronic anxiety disorders. Previous work showed that repeated social defeat (RSD) in mice promoted stress-sensitization that was characterized by the recurrence of anxiety following sub-threshold stress 24 days after RSD. Furthermore, splenectomy following RSD prevented the recurrence of anxiety in stress-sensitized (SS) mice. We hypothesize that the spleen of RSD-exposed mice became a reservoir of primed monocytes that were released following neuroendocrine activation by sub-threshold stress. Methods Mice were subjected to sub-threshold stress (i.e., single cycle of social defeat) 24 days after RSD, and immune and behavioral measures were taken. Results Sub-threshold stress 24 days after RSD re-established anxiety-like behavior that was associated with egress of Ly6Chi monocytes from the spleen. Moreover, splenectomy prior to RSD blocked monocyte trafficking to the brain and prevented anxiety-like behavior following sub-threshold stress. Splenectomy, however, had no effect on monocyte accumulation or anxiety when determined 14 hours after RSD. In addition, splenocytes cultured 24 days after RSD exhibited a primed inflammatory phenotype. Peripheral sympathetic inhibition prior to sub-threshold stress blocked monocyte trafficking from the spleen to the brain and prevented the re-establishment of anxiety in RSD-sensitized mice. Last, β-adrenergic antagonism also prevented splenic monocyte egress after acute stress. Conclusion The spleen served as a unique reservoir of primed monocytes that were readily released following sympathetic activation by sub-threshold stress that promoted the re-establishment of anxiety. Collectively, the long-term storage of primed monocytes in the spleen may have a profound influence on recurring anxiety disorders. PMID:26281717

Simultaneous determination of phenolic acids and flavonoids in rice using solid-phase extraction and RP-HPLC with photodiode array detection.

PubMed

Irakli, Maria N; Samanidou, Victoria F; Biliaderis, Costas G; Papadoyannis, Ioannis N

2012-07-01

An analytical method based on an optimized solid-phase extraction procedure and followed by high-performance liquid chromatography (HPLC) separation with diode array detection was developed and validated for the simultaneous determination of phenolic acids (gallic, protocatechuic, 4-hydroxy-benzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, sinapic, and cinnamic acids), flavanols (catechin and epicatechin), flavonols (myricetin, quercetin, kaempferol, quercetin-3-O-glucoside, hyperoside, and rutin), flavones (luteolin and apigenin) and flavanones (naringenin and hesperidin) in rice flour (Oryza sativa L.). Chromatographic separation was carried out on a PerfectSil Target ODS-3 (250 mm × 4.6 mm, 3 μm) column at temperature 25°C using a mobile phase, consisting of 0.5% (v/v) acetic acid in water, methanol, and acetonitrile at a flow rate 1 mL min(-1) , under gradient elution conditions. Application of optimum extraction conditions, elaborated on both Lichrolut C(18) and Oasis HLB cartridges, have led to extraction of phenolic acids and flavonoids from rice flour with mean recoveries 84.3-113.0%. The developed method was validated in terms of linearity, accuracy, precision, stability, and sensitivity. Repeatability (n = 5) and inter-day precision (n = 4) revealed relative standard deviation (RSD) <13%. The optimized method was successfully applied to the analysis of phenolic acids and flavonoids in pigmented (red and black rice) and non-pigmented rice (brown rice) samples. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous quantification and semi-quantification of ginkgolic acids and their metabolites in rat plasma by UHPLC-LTQ-Orbitrap-MS and its application to pharmacokinetics study.

PubMed

Qian, Yiyun; Zhu, Zhenhua; Duan, Jin-Ao; Guo, Sheng; Shang, Erxin; Tao, Jinhua; Su, Shulan; Guo, Jianming

2017-01-15

A highly sensitive method using ultra-high-pressure liquid chromatography coupled with linear ion trap-Orbitrap tandem mass spectrometry (UHPLC-LTQ-Orbitrap-MS) has been developed and validated for the simultaneous identification and quantification of ginkgolic acids and semi-quantification of their metabolites in rat plasma. For the five selected ginkgolic acids, the method was found to be with good linearities (r>0.9991), good intra- and inter-day precisions (RSD<15%), and good accuracies (RE, from -10.33% to 4.92%) as well. Extraction recoveries, matrix effects and stabilities for rat plasm samples were within the required limits. The validated method was successfully applied to investigate the pharmacokinetics of the five ginkgolic acids in rat plasma after oral administration of 3 dosage groups (900mg/kg, 300mg/kg and 100mg/kg). Meanwhile, six metabolites of GA (15:1) and GA (17:1) were identified by comparison of MS data with reported values. The results of validation in terms of linear ranges, precisions and stabilities were established for semi-quantification of metabolites. The curves of relative changes of these metabolites during the metabolic process were constructed by plotting the peak area ratios of metabolites to salicylic acid (internal standard, IS), respectively. Double peaks were observed in all 3 dose groups. Different type of metabolites and different dosage of each metabolite both resulted in different T max . Copyright © 2016 Elsevier B.V. All rights reserved.

Combination of corona discharge ion mobility spectrometry with a novel reagent gas and two immiscible organic solvent liquid-liquid-liquid microextraction for analysis of clomipramine in biological samples.

PubMed

Saraji, Mohammad; Bidgoli, Ali Akbar Hajialiakbari; Khayamian, Taghi; Moradmand, Ali

2011-12-02

A novel and sensitive method based on combination of two immiscible organic solvents hollow fiber-based liquid-liquid-liquid microextraction and corona discharge ion mobility spectrometry (HF-LLLME-CD-IMS) was employed for the analysis of clomipramine in human urine and plasma. The effect of formic, acetic and propionic acid as the reagent gas (dopant) on the corona discharge ion mobility signal was investigated. The influence of dopant amount was also studied. Optimum mass flow rates of the dopants were 3.7, 1.1 and 1.0 μmol min(-1) for formic, acetic and propionic acid, respectively. Experimental parameters influencing the extraction efficiency of HF-LLLME, such as NaOH concentration as donor solution, ionic strength of the sample, stirring rate, and extraction time were investigated and optimized. Under the optimum conditions, analytical parameters such as linearity, precision and limit of detection were also evaluated. The linear dynamic range was from 1 to 100 μg L(-1) (r(2)=0.9980) and the limit of detection was 0.35 μg L(-1). Intra- and inter-day precisions were satisfactory with a relative standard deviation (RSD) of 5.9 and 6.7%, respectively. The proposed method was satisfactorily applied for the determination of clomipramine in human plasma and urine. Copyright © 2011 Elsevier B.V. All rights reserved.

A robust LC-MS/MS method for the determination of pidotimod in different biological matrixes and its application to in vivo and in vitro pharmacokinetic studies.

PubMed

Wang, Guangji; Wang, Qian; Rao, Tai; Shen, Boyu; Kang, Dian; Shao, Yuhao; Xiao, Jingcheng; Chen, Huimin; Liang, Yan

2016-06-15

Pidotimod, (R)-3-[(S)-(5-oxo-2-pyrrolidinyl) carbonyl]-thiazolidine-4-carboxylic acid, was frequently used to treat children with recurrent respiratory infections. Preclinical pharmacokinetics of pidotimod was still rarely reported to date. Herein, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine pidotimod in rat plasma, tissue homogenate and Caco-2 cells. In this process, phenacetin was chosen as the internal standard due to its similarity in chromatographic and mass spectrographic characteristics with pidotimod. The plasma calibration curves were established within the concentration range of 0.01-10.00μg/mL, and similar linear curves were built using tissue homogenate and Caco-2 cells. The calibration curves for all biological samples showed good linearity (r>0.99) over the concentration ranges tested. The intra- and inter-day precision (RSD, %) values were below 15% and accuracy (RE, %) was ranged from -15% to 15% at all quality control levels. For plasma, tissue homogenate and Caco-2 cells, no obvious matrix effect was found, and the average recoveries were all above 75%. Thus, the method demonstrated excellent accuracy, precision and robustness for high throughput applications, and was then successfully applied to the studies of absorption in rat plasma, distribution in rat tissues and intracellular uptake characteristics in Caco-2 cells for pidotimod. Copyright © 2016 Elsevier B.V. All rights reserved.

Theoretically Guided Analytical Method Development and Validation for the Estimation of Rifampicin in a Mixture of Isoniazid and Pyrazinamide by UV Spectrophotometer

PubMed Central

Khan, Mohammad F.; Rita, Shamima A.; Kayser, Md. Shahidulla; Islam, Md. Shariful; Asad, Sharmeen; Bin Rashid, Ridwan; Bari, Md. Abdul; Rahman, Muhammed M.; Al Aman, D. A. Anwar; Setu, Nurul I.; Banoo, Rebecca; Rashid, Mohammad A.

2017-01-01

A simple, rapid, economic, accurate, and precise method for the estimation of rifampicin in a mixture of isoniazid and pyrazinamide by UV spectrophotometeric technique (guided by the theoretical investigation of physicochemical properties) was developed and validated. Theoretical investigations revealed that isoniazid and pyrazinamide both were freely soluble in water and slightly soluble in ethyl acetate whereas rifampicin was practically insoluble in water but freely soluble in ethyl acetate. This indicates that ethyl acetate is an effective solvent for the extraction of rifampicin from a water mixture of isoniazid and pyrazinamide. Computational study indicated that pH range of 6.0–8.0 would favor the extraction of rifampicin. Rifampicin is separated from isoniazid and pyrazinamide at pH 7.4 ± 0.1 by extracting with ethyl acetate. The ethyl acetate was then analyzed at λmax of 344.0 nm. The developed method was validated for linearity, accuracy and precision according to ICH guidelines. The proposed method exhibited good linearity over the concentration range of 2.5–35.0 μg/mL. The intraday and inter-day precision in terms of % RSD ranged from 1.09 to 1.70% and 1.63 to 2.99%, respectively. The accuracy (in terms of recovery) of the method varied from of 96.7 ± 0.9 to 101.1 ± 0.4%. The LOD and LOQ were found to be 0.83 and 2.52 μg/mL, respectively. In addition, the developed method was successfully applied to determine rifampicin combination (isoniazid and pyrazinamide) brands available in Bangladesh. PMID:28503547

Theoretically Guided Analytical Method Development and Validation for the Estimation of Rifampicin in a Mixture of Isoniazid and Pyrazinamide by UV Spectrophotometer.

PubMed

Khan, Mohammad F; Rita, Shamima A; Kayser, Md Shahidulla; Islam, Md Shariful; Asad, Sharmeen; Bin Rashid, Ridwan; Bari, Md Abdul; Rahman, Muhammed M; Al Aman, D A Anwar; Setu, Nurul I; Banoo, Rebecca; Rashid, Mohammad A

2017-01-01

A simple, rapid, economic, accurate, and precise method for the estimation of rifampicin in a mixture of isoniazid and pyrazinamide by UV spectrophotometeric technique (guided by the theoretical investigation of physicochemical properties) was developed and validated. Theoretical investigations revealed that isoniazid and pyrazinamide both were freely soluble in water and slightly soluble in ethyl acetate whereas rifampicin was practically insoluble in water but freely soluble in ethyl acetate. This indicates that ethyl acetate is an effective solvent for the extraction of rifampicin from a water mixture of isoniazid and pyrazinamide. Computational study indicated that pH range of 6.0-8.0 would favor the extraction of rifampicin. Rifampicin is separated from isoniazid and pyrazinamide at pH 7.4 ± 0.1 by extracting with ethyl acetate. The ethyl acetate was then analyzed at λ max of 344.0 nm. The developed method was validated for linearity, accuracy and precision according to ICH guidelines. The proposed method exhibited good linearity over the concentration range of 2.5-35.0 μg/mL. The intraday and inter-day precision in terms of % RSD ranged from 1.09 to 1.70% and 1.63 to 2.99%, respectively. The accuracy (in terms of recovery) of the method varied from of 96.7 ± 0.9 to 101.1 ± 0.4%. The LOD and LOQ were found to be 0.83 and 2.52 μg/mL, respectively. In addition, the developed method was successfully applied to determine rifampicin combination (isoniazid and pyrazinamide) brands available in Bangladesh.

A validated solid-liquid extraction method for the HPLC determination of polyphenols in apple tissues Comparison with pressurised liquid extraction.

PubMed

Alonso-Salces, Rosa M; Barranco, Alejandro; Corta, Edurne; Berrueta, Luis A; Gallo, Blanca; Vicente, Francisca

2005-02-15

A solid-liquid extraction procedure followed by reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with a photodiode array detector (DAD) for the determination of polyphenols in freeze-dried apple peel and pulp is reported. The extraction step consists in sonicating 0.5g of freeze-dried apple tissue with 30mL of methanol-water-acetic acid (30:69:1, v/v/v) containing 2g of ascorbic acid/L, for 10min in an ultrasonic bath. The whole method was validated, concluding that it is a robust method that presents high extraction efficiencies (peel: >91%, pulp: >95%) and appropriate precisions (within day: R.S.D. (n = 5) <5%, and between days: R.S.D. (n = 5) <7%) at the different concentration levels of polyphenols that can be found in apple samples. The method was compared with one previously published, consisting in a pressurized liquid extraction (PLE) followed by RP-HPLC-DAD determination. The advantages and disadvantages of both methods are discussed.

A pretreatment method for HPLC analysis of cypermethrin in microbial degradation systems.

PubMed

Liu, Shuliang; Yao, Kai; Jia, Dongying; Zhao, Nan; Lai, Wen; Yuan, Huaiyu

2012-07-01

In this paper, a pretreatment method for high-performance liquid chromatography (HPLC) determination of cypermethrin (CY) in microbial degradation systems was systemically studied, primarily to solve the problem of inaccurate determination of CY concentration caused by its uneven distribution in the systems. A suitable pretreatment method was established, including sampling, extraction and dehydration of CY. Partial sampling could be taken for bacterial and yeast systems in which CY was uniformly dispersed by an emulsifying agent, while total sampling was only suitable for mold systems with or without an emulsifying agent. CY could be fully extracted from the samples in which microbial cells were disrupted by ultrasonic treatment with acetonitrile under ultrasonic condition. The extract could be effectively dehydrated and purified by passing it through an anhydrous Na(2)SO(4) column followed by an elution with acetonitrile. The determination of CY in the pretreated sample by HPLC showed a high precision [relative standard deviation (RSD) = 1.14%, n = 5] and a good stability over a period of five days (RSD = 1.57%, n = 5). The recoveries of CY in microbial degradation systems at three different spiked levels ranged from 95.68 to 108.09% (RSD = 0.50-5.87%, n = 5).

Development and validation of dissolution study of sustained release dextromethorphan hydrobromide tablets.

PubMed

Rajan, Sekar; Colaco, Socorrina; Ramesh, N; Meyyanathan, Subramania Nainar; Elango, K

2014-02-01

This study describes the development and validation of dissolution tests for sustained release Dextromethorphan hydrobromide tablets using an HPLC method. Chromatographic separation was achieved on a C18 column utilizing 0.5% triethylamine (pH 7.5) and acetonitrile in the ratio of 50:50. The detection wavelength was 280 nm. The method was validated and response was found to be linear in the drug concentration range of 10-80 microg mL(-1). The suitable conditions were clearly decided after testing sink conditions, dissolution medium and agitation intensity. The most excellent dissolution conditions tested, for the Dextromethorphan hydrobromide was applied to appraise the dissolution profiles. The method was validated and response was found to be linear in the drug concentration range of 10-80 microg mL(-1). The method was established to have sufficient intermediate precision as similar separation was achieved on another instrument handled by different operators. Mean Recovery was 101.82%. Intra precisions for three different concentrations were 1.23, 1.10 0.72 and 1.57, 1.69, 0.95 and inter run precisions were % RSD 0.83, 1.36 and 1.57%, respectively. The method was successfully applied for dissolution study of the developed Dextromethorphan hydrobromide tablets.

Simultaneous quantification of cortisol and cortisone in urines from infants with packed-fiber solid-phase extraction coupled to HPLC-MS/MS.

PubMed

Li, Chen; Zhang, Zhao; Liu, Xiongwei; Shen, Kangwei; Gu, Pan; Kang, Xuejun

2017-09-01

Cortisol and cortisone are two important glucocorticoids in human body, their interconversion is controlled by two isotypes of 11β-hydroxy steroid dehydrogenase (11β-HSD1 and 11β-HSD2). The ratio of urinary cortisol to cortisone can be used to assess the activity of 11β-HSDs. An analytical method to quantify urinary cortisol and cortisone using high performance liquid chromatographic tandem mass spectrometry following a packed-fiber solid-phase extraction (PFSPE) was developed. The proposed method was validated and applied to determine the urinary cortisol and cortisone concentrations in infants. Linearity was observed in the range of 0.6-150ng/mL for cortisol and 0.8-200ng/mL for cortisone. The intra-day RSD was 2.4-4.5% for cortisol and 3.3-6.2% for cortisone. Inter-day RSD was 3.7-6.6% for cortisol and 4.3-8.2% for cortisone. The recovery was 97.8±4.6% for cortisol and 98.9±4.4% for cortisone. The established method is simple and efficient for the quantification of urinary cortisol and cortisone and for indirectly assessing the activity of 11β-hydroxy steroid dehydrogenase. Copyright © 2017 Elsevier B.V. All rights reserved.

Development and validation of a new HPLC-UV method for the simultaneous determination of triclabendazole and ivermectin B1a in a pharmaceutical formulation.

PubMed

Shurbaji, Maher; Abu Al Rub, Mohamad H; Saket, Munib M; Qaisi, Ali M; Salim, Maher L; Abu-Nameh, Eyad S M

2010-01-01

A rapid, simple, and sensitive RP-HPLC analytical method was developed for the simultaneous determination of triclabendazole and ivermectin in combination using a C18 RP column. The mobile phase was acetonitrile-methanol-water-acetic acid (56 + 36 + 7.5 + 0.5, v/v/v/v) at a pH of 4.35 and flow rate of 1.0 mL/min. A 245 nm UV detection wavelength was used. Complete validation, including linearity, accuracy, recovery, LOD, LOQ, precision, robustness, stability, and peak purity, was performed. The calibration curve was linear over the range 50.09-150.26 microg/mL for triclabendazole with r = 0.9999 and 27.01-81.02 microg/mL for ivermectin with r = 0.9999. Calculated LOD and LOQ for triclabendazole were 0.03 and 0.08 microg/mL, respectively, and for ivermectin 0.07 and 0.20 microg/mL, respectively. The intraday precision obtained was 98.71% with RSD of 0.87% for triclabendazole and 100.79% with RSD 0.73% for ivermectin. The interday precision obtained was 99.51% with RSD of 0.35% for triclabendazole and 100.55% with RSD of 0.59% for ivermectin. Robustness was also studied, and there was no significant variation of the system suitability of the analytical method with small changes in experimental parameters.

Inter-laboratory validation of bioaccessibility testing for metals.

PubMed

Henderson, Rayetta G; Verougstraete, Violaine; Anderson, Kim; Arbildua, José J; Brock, Thomas O; Brouwers, Tony; Cappellini, Danielle; Delbeke, Katrien; Herting, Gunilla; Hixon, Greg; Odnevall Wallinder, Inger; Rodriguez, Patricio H; Van Assche, Frank; Wilrich, Peter; Oller, Adriana R

2014-10-01

Bioelution assays are fast, simple alternatives to in vivo testing. In this study, the intra- and inter-laboratory variability in bioaccessibility data generated by bioelution tests were evaluated in synthetic fluids relevant to oral, inhalation, and dermal exposure. Using one defined protocol, five laboratories measured metal release from cobalt oxide, cobalt powder, copper concentrate, Inconel alloy, leaded brass alloy, and nickel sulfate hexahydrate. Standard deviations of repeatability (sr) and reproducibility (sR) were used to evaluate the intra- and inter-laboratory variability, respectively. Examination of the sR:sr ratios demonstrated that, while gastric and lysosomal fluids had reasonably good reproducibility, other fluids did not show as good concordance between laboratories. Relative standard deviation (RSD) analysis showed more favorable reproducibility outcomes for some data sets; overall results varied more between- than within-laboratories. RSD analysis of sr showed good within-laboratory variability for all conditions except some metals in interstitial fluid. In general, these findings indicate that absolute bioaccessibility results in some biological fluids may vary between different laboratories. However, for most applications, measures of relative bioaccessibility are needed, diminishing the requirement for high inter-laboratory reproducibility in absolute metal releases. The inter-laboratory exercise suggests that the degrees of freedom within the protocol need to be addressed. Copyright © 2014 Elsevier Inc. All rights reserved.

Determination of human insulin in dog plasma by a selective liquid chromatography-tandem mass spectrometry method: Application to a pharmacokinetic study.

PubMed

Dong, Shiqi; Zeng, Yong; Wei, Guangli; Si, Duanyun; Liu, Changxiao

2018-03-01

A simple, sensitive and selective LC-MS/MS method for quantitative analysis of human insulin was developed and validated in dog plasma. Insulin glargine was used as the internal standard. After a simple step of solid-phase extraction, the chromatographic separation of human insulin was achieved by using InertSustain Bio C18 column with a mobile phase of acetonitrile containing 1% formic acid (A)-water containing 1% formic acid (B). The detection was performed by positive ion electrospray ionization in multiple-reaction monitoring (MRM) mode. Good linearity was observed in the concentration range of 1-1000 μIU/mL (r 2  > 0.99), and the lower limit of quantification was 1 μIU/mL (equal to 38.46 pg/mL). The intra- and inter-day precision (expressed as relative standard deviation, RSD) of human insulin were ≤12.1% and ≤13.0%, respectively, and the accuracy (expressed as relative error, RE) was in the range of -7.23-11.9%. The recovery and matrix effect were both within acceptable limits. This method was successfully applied for the pharmacokinetic study of human insulin in dogs after subcutaneous administration. Copyright © 2018 Elsevier B.V. All rights reserved.

A sensitive LC-MS/MS method for the quantification of febuxostat in human plasma and its pharmacokinetic application.

PubMed

Vaka, Venkata Rami Reddy; Inamadugu, Jaswanth Kumar; Pilli, Nageswara Rao; Ramesh, Mullangi; Katreddi, Hussain Reddy

2013-11-01

An improved, simple and highly sensitive LC-MS/MS method has been developed and validated for quantification of febuxostat with 100 μL human plasma using febuxostat-d7 as an internal standard (IS) according to regulatory guidelines. The analyte and IS were extracted from human plasma via liquid-liquid extraction using diethyl ether. The chromatographic separation was achieved on a Zorbax C18 column using a mixture of acetonitrile and 5 mm ammonium formate (60:40, v/v) as the mobile phase at a flow rate of 0.5 mL/min. The total run time was 5.0 min and the elution of febuxostat and IS occurred at 1.0 and 1.5 min, respectively. A linear response function was established for the range of concentrations 1-6000 ng/mL (r > 0.99). The precursor to product ion transitions monitored for febuxostat and IS were m/z 317.1 → 261.1 and 324.2 → 262.1, respectively. The intra- and inter-day precisions (%RSD) were within 1.29-9.19 and 2.85-7.69%, respectively. The proposed method was successfully applied to pharmacokinetic studies in humans. Copyright © 2013 John Wiley & Sons, Ltd.

Odour-causing compounds in air samples: gas-liquid partition coefficients and determination using solid-phase microextraction and GC with mass spectrometric detection.

PubMed

Godayol, Anna; Alonso, Mònica; Sanchez, Juan M; Anticó, Enriqueta

2013-03-01

A quantification method based on solid-phase microextraction followed by GC coupled to MS was developed for the determination of gas-liquid partition coefficients and for the air monitoring of a group of odour-causing compounds that had previously been found in wastewater samples including dimethyl disulphide, phenol, indole, skatole, octanal, nonanal, benzothiazole and some terpenes. Using a divinylbenzene/carboxen/polydimethylsiloxane fibre, adsorption kinetics have been studied to define an extraction time that would avoid coating saturation. It was found that for an extraction time of 10 min, external calibration could be performed in the range of 0.4-100 μg/m(3), with detection limits between 0.1 and 20 μg/m(3). Inter-day precision of the developed method was evaluated (n = 5) and RSD values between 12 and 24% were obtained for all compounds. The proposed method has been applied to the analysis of air samples surrounding a wastewater treatment plant in Catalonia (Spain). In all air samples evaluated, dimethyl disulphide, limonene and phenol were detected, and the first two were the compounds that showed the highest partition coefficients. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Degradation of fluoroquinolone antibiotics and identification of metabolites/transformation products by liquid chromatography-tandem mass spectrometry.

PubMed

Maia, Alexandra S; Ribeiro, Ana R; Amorim, Catarina L; Barreiro, Juliana C; Cass, Quezia B; Castro, Paula M L; Tiritan, Maria Elizabeth

2014-03-14

Antibiotics are a therapeutic class widely found in environmental matrices and extensively studied due to its persistence and implications for multi-resistant bacteria development. This work presents an integrated approach of analytical multi-techniques on assessing biodegradation of fluorinated antibiotics at a laboratory-scale microcosmos to follow removal and formation of intermediate compounds. Degradation of four fluoroquinolone antibiotics, namely Ofloxacin (OFL), Norfloxacin (NOR), Ciprofloxacin (CPF) and Moxifloxacin (MOX), at 10 mg L(-1) using a mixed bacterial culture, was assessed for 60 days. The assays were followed by a developed and validated analytical method of LC with fluorescence detection (LC-FD) using a Luna Pentafluorophenyl (2) 3 μm column. The validated method demonstrated good selectivity, linearity (r(2)>0.999), intra-day and inter-day precisions (RSD<2.74%) and accuracy. The quantification limits were 5 μg L(-1) for OFL, NOR and CPF and 20 μg L(-1) for MOX. The optimized conditions allowed picturing metabolites/transformation products formation and accumulation during the process, stating an incomplete mineralization, also shown by fluoride release. OFL and MOX presented the highest (98.3%) and the lowest (80.5%) extent of degradation after 19 days of assay, respectively. A representative number of samples was selected and analyzed by LC-MS/MS with triple quadrupole and the molecular formulas were confirmed by a quadruple time of flight analyzer (QqTOF). Most of the intermediates were already described as biodegradation and/or photodegradation products in different conditions; however unknown metabolites were also identified. The microbial consortium, even when exposed to high levels of FQ, presented high percentages of degradation, never reported before for these compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of psilocybin in Psilocybe semilanceata by capillary zone electrophoresis.

PubMed

Pedersen-Bjergaard, S; Sannes, E; Rasmussen, K E; Tønnesen, F

1997-07-04

A capillary zone electrophoretic (CZE) method was developed for the rapid determination of psilocybin in Psilocybe semilanceata. Following a simple two step extraction with 3.0+2.0 ml methanol, the hallucinogenic compound was effectively separated from matrix components by CZE utilizing a 10 mM borate-phosphate running buffer adjusted to pH 11.5. The identity of psilocybin was confirmed by migration time information and by UV spectra, while quantitation was accomplished utilizing barbital as internal standard. The calibration curve for psilocybin was linear within 0.01-1 mg/ml, while intra-day and inter-day variations of quantitative data were 0.5 and 2.5% R.S.D., respectively. In addition to psilocybin, the method was also suitable for the determination of the structurally related compound baeocystin.

Qualitative and quantitative analysis of nine major compounds in the Bozhougyiqi-Tang using a high-performance liquid chromatography coupled with a diode array detector and electrospray ionization mass spectrometer

PubMed Central

Weon, Jin Bae; Ma, Jin Yeul; Yang, Hye Jin; Lee, Bohyoung; Yun, Bo-Ra; Ma, Choong Je

2013-01-01

Background: Bozhougyiqi-Tang (BZYQT) is of traditional herbal medicine used for enhancement of digestive capacity. Objective: An accurate and reliable simultaneous determination using a HPLC-DAD and ESI-MS was developed and validated for the qualitative and quantitative analysis of 9 major compounds, ferulic acid (1), naringin (2), hesperidin (3), decursinol (4), glycyrrhizin (5), saikosaponin A (6), 6-gingerol (7), ginsenoside Rg3 (8), decursin (9), in traditional herbal medicine ‘Bozhougyiqi-Tang.’ Materials and Methods: The chromatographic separation of 9 compounds was performed on a SHISEIDO C18 column (250 mm × 4.6 mm i.d., S-5 μm) using gradient elution with 0.1% trifluoroacetic acid and acetonitrile at a flow rate of 1.0 ml/min. The 9 compounds were identified based on peak retention time and UV spectrum and MS data of these compounds. Results: This developed method showed good linearity (R2 > 0.999). The LOD and LOQ of the major compounds were less than 0.09 and 0.28 μg/ml, respectively. The intra - day and inter - day RSD values were within 2.06% and 1.64%, respectively. The mean recoveries were from 92.10% to 108.56% with less than 1.88%. The results indicated that established method had good precision and accuracy. Conclusion: The new method was successfully applied to the simultaneous analysis of 9 compounds in Bozhougyiqi-Tangs samples. PMID:23930013

A visual detection of protein content based on titration of moving reaction boundary electrophoresis.

PubMed

Wang, Hou-Yu; Guo, Cheng-Ye; Guo, Chen-Gang; Fan, Liu-Yin; Zhang, Lei; Cao, Cheng-Xi

2013-04-24

A visual electrophoretic titration method was firstly developed from the concept of moving reaction boundary (MRB) for protein content analysis. In the developed method, when the voltage was applied, the hydroxide ions in the cathodic vessel moved towards the anode, and neutralized the carboxyl groups of protein immobilized via highly cross-linked polyacrylamide gel (PAG), generating a MRB between the alkali and the immobilized protein. The boundary moving velocity (V(MRB)) was as a function of protein content, and an acid-base indicator was used to denote the boundary displacement. As a proof of concept, standard model proteins and biological samples were chosen for the experiments to study the feasibility of the developed method. The experiments revealed that good linear calibration functions between V(MRB) and protein content (correlation coefficients R>0.98). The experiments further demonstrated the following merits of developed method: (1) weak influence of non-protein nitrogen additives (e.g., melamine) adulterated in protein samples, (2) good agreement with the classic Kjeldahl method (R=0.9945), (3) fast measuring speed in total protein analysis of large samples from the same source, and (4) low limit of detection (0.02-0.15 mg mL(-1) for protein content), good precision (R.S.D. of intra-day less than 1.7% and inter-day less than 2.7%), and high recoveries (105-107%). Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Simultaneous extraction and determination of albendazole and triclabendazole by a novel syringe to syringe dispersive liquid phase microextraction-solidified floating organic drop combined with high performance liquid chromatography.

PubMed

Asadi, Mohammad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad

2016-08-17

A syringe to syringe dispersive liquid phase microextraction-solidified floating organic drop was introduced and used for the simultaneous extraction of trace amounts of albendazole and triclabendazole from different matrices. The extracted analytes were determined by high performance liquid chromatography along with fluorescence detection. The analytical parameters affecting the microextraction efficiency including the nature and volume of the extraction solvent, sample volume, sample pH, ionic strength and the cycles of extraction were optimized. The calibration curves were linear in the range of 0.1-30.0 μg L(-1) and 0.2-30.0 μg L(-1) with determination coefficients of 0.9999 and 0.9998 for albendazole and triclabendazole respectively. The detection limits defined as three folds of the signal to noise ratio were found to be 0.02 μg L(-1) for albendazole and 0.06 μg L(-1) for triclabendazole. The inter-day and intra-day precision (RSD%) for both analytes at three concentration levels (0.5, 2.0 and 10.0 μg L(-1)) were in the range of 6.3-10.1% and 5.0-7.5% respectively. The developed method was successfully applied to determine albendazole and triclabendazole in water, cow milk, honey, and urine samples. Copyright © 2016. Published by Elsevier B.V.

A validated bioanalytical HPLC method for pharmacokinetic evaluation of 2-deoxyglucose in human plasma.

PubMed

Gounder, Murugesan K; Lin, Hongxia; Stein, Mark; Goodin, Susan; Bertino, Joseph R; Kong, Ah-Ng Tony; DiPaola, Robert S

2012-05-01

2-Deoxyglucose (2-DG), an analog of glucose, is widely used to interfere with glycolysis in tumor cells and studied as a therapeutic approach in clinical trials. To evaluate the pharmacokinetics of 2-DG, we describe the development and validation of a sensitive HPLC fluorescent method for the quantitation of 2-DG in plasma. Plasma samples were deproteinized with methanol and the supernatant was dried at 45°C. The residues were dissolved in methanolic sodium acetate-boric acid solution. 2-DG and other monosaccharides were derivatized to 2-aminobenzoic acid derivatives in a single step in the presence of sodium cyanoborohydride at 80°C for 45 min. The analytes were separated on a YMC ODS C₁₈ reversed-phase column using gradient elution. The excitation and emission wavelengths were set at 360 and 425 nm. The 2-DG calibration curves were linear over the range of 0.63-300 µg/mL with a limit of detection of 0.5 µg/mL. The assay provided satisfactory intra-day and inter-day precision with RSD less than 9.8%, and the accuracy ranged from 86.8 to 110.0%. The HPLC method is reproducible and suitable for the quantitation of 2-DG in plasma. The method was successfully applied to characterize the pharmacokinetics profile of 2-DG in patients with advanced solid tumors. Copyright © 2011 John Wiley & Sons, Ltd.

Sensitive spectrophotometric determination of aceclofenac following azo dye formation with 4-carboxyl-2,6-dinitrobenzene diazonium ion.

PubMed

Aderibigbe, Segun A; Adegoke, Olajire A; Idowu, Olakunle S; Olaleye, Sefiu O

2012-01-01

The study is a description of a sensitive spectrophotometric determination of aceclofenac following azo dye formation with 4-carboxyl-2,6-dinitrobenzenediazonium ion (CDNBD). Spot test and thin layer chromatography revealed the formation of a new compound distinct from CDNBD and aceclofenac. Optimization studies established a reaction time of 5 min at 30 degrees C after vortex mixing the drug/CDNBD for 10 s. An absorption maximum of 430 nm was selected as analytical wavelength. A linear response was observed over 1.2-4.8 μg/mL of aceclofenac with a correlation coefficient of 0.9983 and the drug combined with CDNBD at stoichiometric ratio of 2 : 1. The method has a limit of detection of 0.403 μg/mL, limit of quantitation of 1.22 μg/mL and is reproducible over a three day assessment. The method gave Sandell's sensitivity of 3.279 ng/cm2. Intra- and inter-day accuracies (in terms of errors) were less than 6% while precisions were of the order of 0.03-1.89% (RSD). The developed spectrophotometric method is of equivalent accuracy (p > 0.05) with British Pharmacopoeia, 2010 potentiometric method. It has the advantages of speed, simplicity, sensitivity and more affordable instrumentation and could found application as a rapid and sensitive analytical method of aceclofenac. It is the first described method by azo dye derivatization for the analysis of aceclofenac in bulk samples and dosage forms.

Imipramine attenuates neuroinflammatory signaling and reverses stress-induced social avoidance.

PubMed

Ramirez, Karol; Shea, Daniel T; McKim, Daniel B; Reader, Brenda F; Sheridan, John F

2015-05-01

Psychosocial stress is associated with altered immunity, anxiety and depression. Previously we showed that repeated social defeat (RSD) promoted microglia activation and social avoidance behavior that persisted for 24days after cessation of RSD. The aim of the present study was to determine if imipramine (a tricyclic antidepressant) would reverse RSD-inducedsocial avoidance and ameliorate neuroinflammatory responses. To test this, C57BL/6 mice were divided into treatment groups. One group from RSD and controls received daily injections of imipramine for 24days, following 6 cycles of RSD. Two other groups were treated with saline. RSD mice spent significantly less time in the interaction zone when an aggressor was present in the cage. Administration of imipramine reversed social avoidance behavior, significantly increasing the interaction time, so that it was similar to that of control mice. Moreover, 24days of imipramine treatment in RSD mice significantly decreased stress-induced mRNA levels for IL-6 in brain microglia. Following ex vivo LPS stimulation, microglia from mice exposed to RSD, had higher mRNA expression of IL-6, TNF-α, and IL-1β, and this was reversed by imipramine treatment. In a second experiment, imipramine was added to drinking water confirming the reversal of social avoidant behavior and decrease in mRNA expression of IL-6 in microglia. These data suggest that the antidepressant imipramine may exert its effect, in part, by down-regulating microglial activation. Copyright © 2015 Elsevier Inc. All rights reserved.

Imipramine attenuates neuroinflammatory signaling and reverses stress-induced social avoidance

PubMed Central

Ramirez, Karol; Shea, Daniel T.; McKim, Daniel B.; B.F., Reader; Sheridan, John F.

2015-01-01

Psychosocial stress is associated with altered immunity, anxiety and depression. Previously we showed that repeated social defeat (RSD) promoted microglia activation and social avoidance behavior that persisted for 24 days after cessation of RSD. The aim of the present study was to determine if imipramine (a tricyclic antidepressant) would reverse RSD-induced social avoidance and ameliorate neuroinflammatory responses. To test this, C57BL/6 mice were divided into treatment groups. One group from RSD and controls received daily injections of imipramine for 24 days, following 6 cycles of RSD. Two other groups were treated with saline. RSD mice spent significantly less time in the interaction zone when an aggressor was present in the cage. Administration of imipramine reversed social avoidance behavior, significantly increasing the interaction time, so that it was similar to that of control mice. Moreover, 24 days of imipramine treatment in RSD mice significantly decreased stress-induced mRNA levels for IL-6 in brain microglia. Following ex vivo LPS stimulation, microglia from mice exposed to RSD, had higher mRNA expression of IL-6, TNF-α, and IL-1β, and this was reversed by imipramine treatment. In a second experiment, imipramine was added to drinking water confirming the reversal of social avoidant behavior and decrease in mRNA expression of IL-6 in microglia. These data suggest that the antidepressant imipramine may exert its effect, in part, by down-regulating microglial activation. PMID:25701613

Effects of renal sympathetic denervation and angiotensin-converting enzyme inhibitor on left ventricular hypertrophy. Comparison in spontaneously hypertensive rats.

PubMed

Ding, X; Xu, X; Yan, Y; Song, X; Liu, S; Wang, G; Su, D; Jing, Q; Qin, Y

2015-06-01

The aim of this study was to investigate whether renal sympathetic denervation (RSD) is more effective on myocardial hypertrophy than the angiotensin-converting enzyme inhibitor (ACEI) perindopril in spontaneously hypertensive rats (SHRs). After bilateral renal denervation blood pressure (BP) was measured every 10 days. On day 50 the heart was (histo)pathologically examined. The ventricular weight to body weight ratios (VW/BW), myocardial diameter and collagen volume fraction (CVF) were calculated, and cardiac hypertrophy marker genes were analyzed by RT-PCR. At the baseline evaluation all groups had comparable BP. After treatment the BP of the RSD group was significantly reduced (p < 0.05). The BP of the RSD group was lower than that of the perindopril group on days 10, 20 and 30th (p < 0.05) but on day 50 systolic BP of the RSD group was significantly higher (p < 0.05) whereas there were no significant differences in diastolic BP. The VW/BW decreased in the RSD group, whereas the value did not change significantly in the perindopril group. The myocardial diameter of the left ventricular cardiomyocytes was also significantly lower in the RSD group and stayed the same in the perindopril group. Collagen volume fraction (CVF) in the RSD group was significantly lower than in the perindopril group (p < 0.05). Significant changes in the expression levels of NPPA, MYH7, and MYH6 (P < 0.05) were observed in the RD-SHR groups (p < 0.05). There was a significant difference in the expression level of MYH6 (p < 0.05) between the RSD group and the perindopril group but the expression levels of NPPA and MYH7 were not significantly different. In this study, RSD had a significant antihypertensive effect and inhibited hypertensive-induced cardiac hypertrophy in SHRs and showed advantages compared with ACEI in decreasing BP in the early stage and in inhibiting myocardial fibrosis.

Analysis of L-citrulline and L-arginine in Ficus deltoidea leaf extracts by reverse phase high performance liquid chromatography

PubMed Central

Shafaei, Armaghan; Aisha, Abdalrahim F. A.; Siddiqui, Mohammad Jamshed Ahmad; Ismail, Zhari

2015-01-01

Background: Ficus deltoidea (FD) is one of the native plants widely distributed in several countries in Southeast Asia. Previous studies have shown that FD leaf possess antinociceptive, wound healing and antioxidant properties. These beneficial effects have been attributed to the presence of primary and secondary metabolites such as polyphenols, amino acids and flavonoids. Objective: The aim was to develop a reverse phase high-performance liquid chromatography method with ultraviolet detection that involves precolumn derivatisation with O-phthaladehyde for simultaneous analysis of two amino acids L-citrulline and L-arginine in FD leaf extracts. Materials and Methods: An isocratic elution program consisting of methanol: acetonitrile: Water at 45:45:10 v/v (solvent A) and 0.1 M phosphate buffer pH 7.5 (solvent B) at A: B v/v ratio of 80:20 on Zorbax Eclipse C18 SB-Aq column (250 × 4.6 mm, 5 μm) were used. The flow rate was set at 1 ml/min and detection was carried out at 338 nm with 30 min separation time. Results: Good linearity for L-citrulline and L-arginine was obtained in the range 0.1-1000 μg/ml at R2 ≥ 0.998. The limit of detection and limit of quantification values for both L-citrulline and L-arginine were 1 and 5 μg/ml, respectively. The average of recoveries was in the range 94.94-101.95%, with relative standard deviation (%RSD) less than 3%. Intra- and inter-day precision was in the range 96.36-102.43% with RSD less than 2%. Conclusion: All validation parameters of the developed method indicate the method is reliable and efficient for simultaneous determination of L-citrulline and L-arginine for routine analysis of FD. PMID:25598632

Determination of 21 drugs in oral fluid using fully automated supported liquid extraction and UHPLC-MS/MS.

PubMed

Valen, Anja; Leere Øiestad, Åse Marit; Strand, Dag Helge; Skari, Ragnhild; Berg, Thomas

2017-05-01

Collection of oral fluid (OF) is easy and non-invasive compared to the collection of urine and blood, and interest in OF for drug screening and diagnostic purposes is increasing. A high-throughput ultra-high-performance liquid chromatography-tandem mass spectrometry method for determination of 21 drugs in OF using fully automated 96-well plate supported liquid extraction for sample preparation is presented. The method contains a selection of classic drugs of abuse, including amphetamines, cocaine, cannabis, opioids, and benzodiazepines. The method was fully validated for 200 μL OF/buffer mix using an Intercept OF sampling kit; validation included linearity, sensitivity, precision, accuracy, extraction recovery, matrix effects, stability, and carry-over. Inter-assay precision (RSD) and accuracy (relative error) were <15% and 13 to 5%, respectively, for all compounds at concentrations equal to or higher than the lower limit of quantification. Extraction recoveries were between 58 and 76% (RSD < 8%), except for tetrahydrocannabinol and three 7-amino benzodiazepine metabolites with recoveries between 23 and 33% (RSD between 51 and 52 % and 11 and 25%, respectively). Ion enhancement or ion suppression effects were observed for a few compounds; however, to a large degree they were compensated for by the internal standards used. Deuterium-labelled and 13 C-labelled internal standards were used for 8 and 11 of the compounds, respectively. In a comparison between Intercept and Quantisal OF kits, better recoveries and fewer matrix effects were observed for some compounds using Quantisal. The method is sensitive and robust for its purposes and has been used successfully since February 2015 for analysis of Intercept OF samples from 2600 cases in a 12-month period. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Multi-objective optimization strategy based on desirability functions used for electrophoratic separation and quantification of rosiglitazone and glimepiride in plasma and formulations.

PubMed

Hefnawy, Mohamed M; Sultan, Maha A; Al-Johar, Haya I; Kassem, Mohamed G; Aboul-Enein, Hassan Y

2012-01-01

Multiple response simultaneous optimization employing Derringer's desirability function was used for the development of a capillary electrophoresis method for the simultaneous determination of rosiglitazone (RSG) and glimepiride (GLM) in plasma and formulations. Twenty experiments, taking the two resolutions, the analysis time, and the capillary current as the responses with three important factors--buffer morality, volte and column temperature--were used to design mathematical models. The experimental responses were fitted into a second order polynomial and the six responses were simultaneously optimized to predict the optimum conditions for the effective separation of the studied compounds. The separation was carried out by using capillary zone electrophoresis (CZE) with a silica capillary column and diode array detector at 210 nm. The optimum assay conditions were 52 mmol l⁻¹ phosphate buffer, pH 7, and voltage of 22 kV at 29 °C. The method showed good agreement between the experimental data and predictive value throughout the studied parameter space. The assay limit of detection was 0.02 µg ml⁻¹ and the effective working range at relative standard deviation (RSD) of ≤ 5% was 0.05-16 µg ml⁻¹ (r = 0.999) for both drugs. Analytical recoveries of the studied drugs from spiked plasma were 97.2-101.9 ± 0.31-3.0%. The precision of the assay was satisfactory; RSD was 1.07 and 1.14 for intra- and inter-assay precision, respectively. The proposed method has a great value in routine analysis of RSG and GLM for its therapeutic monitoring and pharmacokinetic studies. Copyright © 2011 John Wiley & Sons, Ltd.

Precise and accurate isotope ratio measurements by ICP-MS.

PubMed

Becker, J S; Dietze, H J

2000-09-01

The precise and accurate determination of isotope ratios by inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) is important for quite different application fields (e.g. for isotope ratio measurements of stable isotopes in nature, especially for the investigation of isotope variation in nature or age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, quality assurance of fuel material, for reprocessing plants, nuclear material accounting and radioactive waste control, for tracer experiments using stable isotopes or long-lived radionuclides in biological or medical studies). Thermal ionization mass spectrometry (TIMS), which used to be the dominant analytical technique for precise isotope ratio measurements, is being increasingly replaced for isotope ratio measurements by ICP-MS due to its excellent sensitivity, precision and good accuracy. Instrumental progress in ICP-MS was achieved by the introduction of the collision cell interface in order to dissociate many disturbing argon-based molecular ions, thermalize the ions and neutralize the disturbing argon ions of plasma gas (Ar+). The application of the collision cell in ICP-QMS results in a higher ion transmission, improved sensitivity and better precision of isotope ratio measurements compared to quadrupole ICP-MS without the collision cell [e.g., for 235U/238U approximately 1 (10 microg x L(-1) uranium) 0.07% relative standard deviation (RSD) vs. 0.2% RSD in short-term measurements (n = 5)]. A significant instrumental improvement for ICP-MS is the multicollector device (MC-ICP-MS) in order to obtain a better precision of isotope ratio measurements (with a precision of up to 0.002%, RSD). CE- and HPLC-ICP-MS are used for the separation of isobaric interferences of long-lived radionuclides and stable isotopes by determination of spallation nuclide abundances in an irradiated tantalum target.

Plus disease in retinopathy of prematurity: a continuous spectrum of vascular abnormality as basis of diagnostic variability

PubMed Central

Campbell, J. Peter; Kalpathy-Cramer, Jayashree; Erdogmus, Deniz; Tian, Peng; Kedarisetti, Dharanish; Moleta, Chace; Reynolds, James D.; Hutcheson, Kelly; Shapiro, Michael J.; Repka, Michael X.; Ferrone, Philip; Drenser, Kimberly; Horowitz, Jason; Sonmez, Kemal; Swan, Ryan; Ostmo, Susan; Jonas, Karyn E.; Chan, R.V. Paul; Chiang, Michael F.

2016-01-01

Objective To identify patterns of inter-expert discrepancy in plus disease diagnosis in retinopathy of prematurity (ROP). Design We developed two datasets of clinical images of varying disease severity (100 images and 34 images) as part of the Imaging and Informatics in ROP study, and determined a consensus reference standard diagnosis (RSD) for each image, based on 3 independent image graders and the clinical exam. We recruited 8 expert ROP clinicians to classify these images and compared the distribution of classifications between experts and the RSD. Subjects, Participants, and/or Controls Images obtained during routine ROP screening in neonatal intensive care units. 8 participating experts with >10 years of clinical ROP experience and >5 peer-reviewed ROP publications. Methods, Intervention, or Testing Expert classification of images of plus disease in ROP. Main Outcome Measures Inter-expert agreement (weighted kappa statistic), and agreement and bias on ordinal classification between experts (ANOVA) and the RSD (percent agreement). Results There was variable inter-expert agreement on diagnostic classifications between the 8 experts and the RSD (weighted kappa 0 – 0.75, mean 0.30). RSD agreement ranged from 80 – 94% agreement for the dataset of 100 images, and 29 – 79% for the dataset of 34 images. However, when images were ranked in order of disease severity (by average expert classification), the pattern of expert classification revealed a consistent systematic bias for each expert consistent with unique cut points for the diagnosis of plus disease and pre-plus disease. The two-way ANOVA model suggested a highly significant effect of both image and user on the average score (P<0.05, adjusted R2=0.82 for dataset A, and P< 0.05 and adjusted R2 =0.6615 for dataset B). Conclusions and Relevance There is wide variability in the classification of plus disease by ROP experts, which occurs because experts have different “cut-points” for the amounts of vascular abnormality required for presence of plus and pre-plus disease. This has important implications for research, teaching and patient care for ROP, and suggests that a continuous ROP plus disease severity score may more accurately reflect the behavior of expert ROP clinicians, and may better standardize classification in the future. PMID:27591053

The LC-MS method for the simultaneous analysis of selected fat-soluble vitamins and their metabolites in serum samples obtained from pediatric patients with cystic fibrosis.

PubMed

Konieczna, Lucyna; Kaźmierska, Katarzyna; Roszkowska, Anna; Szlagatys-Sidorkiewicz, Agnieszka; Bączek, Tomasz

2016-05-30

Cystic fibrosis (CF) is one of the most common genetic diseases in children and affects mainly respiratory and digestive system functions. Despite the prolonged supplementation of vitamins, malnutrition manifested by poor growth and weight loss in children is a major complication in CF related to pancreatic insufficiency and difficulty in absorbing fat-soluble vitamins. In the present study, we have developed and validated a sensitive and accurate high-performance liquid chromatography coupled to mass spectrometry (LC-MS) method for the simultaneous quantification of three fat-soluble vitamins (A, E and K1) and two vitamin D3 active metabolites: 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 in serum samples obtained from pediatric patients with CF. In optimized conditions, the LC-MS method was highly sensitive and presented excellent linearity with a regression coefficient higher than 0.999. The accuracy was in the range of 87.55-95.58 % for all analytes. The precision of the method, expressed as% RSD, ranged from 1.36 % to 3.74 % as the intra-day variability and from 2.35 % to 7.98 % as the inter-day precision for all the studied compounds. Sample preparation included a protein precipitation step with the use of methanol followed by liquid-liquid extraction with n-hexane. The statistical analysis (t-test and principal component analysis (PCA)) of the obtained results revealed significant changes in the plasma level of the analyzed compounds, with 25-hydroxyvitamin D3, vitamin E and K1 present at extremely low concentrations in patients with cystic fibrosis in comparison to healthy controls. The elaborated method reached the expectations for the fast and reliable assessment of fat-soluble vitamin status in children with cystic fibrosis in order to diagnose the disease and monitor the treatment process. Copyright © 2016 Elsevier B.V. All rights reserved.

New Spectrophotometric Assay of Pyrantel Pamoate in Pharmaceuticals and Spiked Human Urine Using Three Complexing Agents

NASA Astrophysics Data System (ADS)

Swamy, N.; Prashanth, K. N.; Basavaiah, K.

2015-07-01

Three simple, rapid, inexpensive, and highly sensitive spectrophotometric methods are described for the quantifi cation of pyrantel pamoate (PYP) in pure drug and formulations. The methods are based on the molecular charge-transfer (CT) complexation reaction involving pyrantel base (PYL) as n-donor and iodine as σ-acceptor (I 2 , method A), and 2,4-dinitrophenol (DNP, method B) or picric acid (PA, method C) as π-acceptors. Spectrophotometrically, the CT complexes showed absorption maxima at 380, 420, and 430 nm, for methods A, B, and C, respectively. Under optimum conditions, Beer's law was obeyed over the concentration ranges 0.12-2.9, 0.12-3.75, and 0.12-2.9 μg/ml for methods A, B, and C, respectively. The apparent molar absorptivity of the CT complexes at the respective λmax are calculated to be 2.63 × 10 5 , 6.91 × 10 4 , and 1.73 × 10 5 l/mol· cm respectively and the corresponding Sandell sensitivity values are 0.0009, 0.003, and 0.0012. The limits of detection (LOD) and quantification (LOQ) are calculated to be (0.02 and 0.07), (0.05 and 0.15), and (0.02 and 0.07) μg/ml with methods A, B, and C, respectively. The intra-day and inter-day accuracy expressed as %RE and precision expressed as %RSD are less than 3%. The methods have been applied to the determination of PYP in tablets, suspensions, and spiked human urine. Parallel assay by a reference method and statistical analysis of the results obtained show no significant difference between the proposed methods and the reference method with respect to accuracy and precision, as evident from the Student's t and variation ratio tests. The accuracy of the methods has been further ascertained by recovery tests via the standard addition technique.

A dispersive liquid-liquid microextraction based on solidification of floating organic droplet followed by injector port silylation coupled with gas chromatography-tandem mass spectrometry for the determination of nine bisphenols in bottled carbonated beverages.

PubMed

Mandrah, Kapil; Satyanarayana, G N V; Roy, Somendu Kumar

2017-12-15

In the present study, a method has been efficiently developed for the first time to determine nine bisphenol analogues [bisphenol A (BPA), bisphenol C (BPC), bisphenol AF (BPAF), bisphenol E (BPE), bisphenol F (BPF), bisphenol G (BPG), bisphenol M (BPM), bisphenol S (BPS), and bisphenol Z (BPZ)] together in bottled carbonated beverages (collected from the local market of Lucknow, India) using dispersive liquid-liquid microextraction process. This is based on solidification of floating organic droplet (DLLME-SFO) followed by injector port silylation coupled with gas chromatography-tandem mass spectrometry. The process investigated parameters of DLLME-SFO (including the type of extraction and disperser solvents with their volumes, effect of pH, ionic strength, and the sample volume), factors influencing to injection port derivatization like, collision energy, injector port temperature, derivatizing reagent with sample injection volume, and type of organic solvent. BPA, BPF, BPZ, and BPS were detected in each sample; whereas, other bisphenols were also detected in some carbonated beverage samples. After optimizing the required conditions, good linearity of analytes was achieved in the range of 0.097-100ngmL -1 with coefficients of determination (R 2 )≥0.995. Intra-day and inter day precision of the method was good, with relative standard deviation (% RSD)≤10.95%. The limits of detection (LOD) and limits of quantification (LOQ) values of all bisphenols were ranged from 0.021 to 0.104ngmL -1 and 0.070 to 0.343ngmL -1 , respectively. The recovery of extraction was good (73.15-95.08%) in carbonated beverage samples and good enrichment factors (96.36-117.33) were found. Thus, the developed method of microextraction was highly precise, fast, and reproducible to determine the level of contaminants in bottled carbonated beverages. Copyright © 2017 Elsevier B.V. All rights reserved.

Repeated social defeat-induced neuroinflammation, anxiety-like behavior and resistance to fear extinction were attenuated by the cannabinoid receptor agonist WIN55,212-2.

PubMed

Lisboa, Sabrina Francesca; Niraula, Anzela; Resstel, Leonardo Barbosa; Guimaraes, Francisco Silveira; Godbout, Jonathan P; Sheridan, John F

2018-04-17

Psychosocial stress contributes to the development of psychiatric disorders. Repeated social defeat (RSD) is a murine stressor that causes a release of inflammatory monocytes into circulation. Moreover, RSD-induced anxiety-like behavior is dependent on the recruitment of these monocytes to the brain. Activation of the endocannabinoid (ECB) system may modulate both neuroendocrine and inflammatory responses mediated by stress. Therefore, we hypothesized that a cannabinoid receptor agonist would attenuate RSD-induced inflammation, anxiety, and stress sensitization. To test this hypothesis, mice received an injection of the synthetic cannabinoid 1/2 receptor agonist, WIN55,212-2 (WIN; 1 mg/kg, intraperitoneally) daily for six consecutive days, 30 min before each exposure to RSD. Anxiety-like behavior, immune activation, neuroinflammation, and microglial reactivity were determined 14 h after RSD. RSD-induced anxiety-like behavior in the open field and in the EPM was reversed by WIN55,212-2. Moreover, WIN55,212-2 reduced the accumulation of inflammatory monocytes in circulation and brain after RSD and attenuated RSD-induced interleukin-1β (IL-1β) messenger RNA (mRNA) expression in microglia/macrophages. Increased ex vivo reactivity of microglia/monocytes to lipopolysaccharides (LPS) after RSD was also attenuated by WIN55,212-2. Next, fear expression, extinction, and recall were evaluated 24 and 48 h, respectively, after contextual fear conditioning, which took place 7 days after RSD. Here, RSD caused prolonged fear expression and impaired fear extinction recall, which was associated with increased IL-1β mRNA in the brain. Moreover, these stress-induced effects were reversed by WIN55,212-2. In conclusion, activation of cannabinoid receptors limited the immune and neuroinflammatory responses to RSD and reversed the short-term and long-term behavioral deficits associated with RSD.

Rapid determination of N,N-diethyl-m-toluamide and permethrin in human plasma by gas chromatography-mass spectrometry and pyridostigmine bromide by high-performance liquid chromatography.

PubMed

Cherstniakova, Svetlana A; Garcia, Gregory E; Strong, John; Bi, Daoqin; Weitz, Julie; Roy, Michael J; Cantilena, Louis R

2006-01-01

A rapid and highly sensitive gas chromatography-mass spectrometry (GC-MS) method for simultaneous determination of N,N-diethyl-m-toluamide (DEET) and permethrin with (2)H(10)-phenanthrene (98 atom %) as an internal standard and a separate external standard high-performance liquid chromatography (HPLC) method for pyridostigmine bromide (PB) determination in human plasma were developed and validated. The GC-MS method for DEET and permethrin quantification utilizes a one-step extraction with tert-butylmethylether. The HPLC method for PB quantification involves a solid-phase extraction and UV detection. The range of the analytical method for DEET and permethrin was 1 ng/mL to 100 ng/mL and for PB was 5 ng/mL to 100 ng/mL. Recovery from plasma proved to be more than 80%. The intraday precision ranged from 1.3% to 8% for DEET, from 2.1% to 11.4% for permethrin, and from 3.0% to 4.8% for PB. The interday precision was 3% for DEET, ranged from 5% to 9% for permethrin, and from 5% to 9% for PB. The accuracy for the limit of quantification was 92% +/- 8% relative standard deviation (RSD) for DEET, 112% +/- 11% RSD for permethrin, and 109% +/- 5% RSD for PB. All 3 compounds were stable in human plasma at -80 degrees C for at least 12 months and after 2 freeze-thaw cycles with RSD values ranging from 7.1% (DEET, 80 ng/mL) to 8.1% (DEET, 8 ng/mL), from 2.3% (permethrin, 80 ng/mL) to 11.6 % (permethrin, 8 ng/mL), and from 0.2% (PB, 80 ng/mL) to 3.6% (PB, 8 ng/mL). Both methods were successfully applied to pharmacokinetic/ pharmacodynamic studies of combined exposure of DEET (skin application), permethrin (treated uniforms), and PB (30 mg orally three times/day for four doses) in healthy volunteers (n = 81).

Chip-based nanoflow high performance liquid chromatography coupled to mass spectrometry for profiling of soybean flavonoids.

PubMed

Chang, Yuwei; Zhao, Chunxia; Wu, Zeming; Zhou, Jia; Zhao, Sumin; Lu, Xin; Xu, Guowang

2012-08-01

In this work a chip-based nano HPLC coupled MS (HPLC-chip/MS) method with a simple sample preparation procedure was developed for the flavonoid profiling of soybean. The analytical properties of the method including the linearity (R(2) , 0.992-0.995), reproducibility (RSD, 1.50-7.66%), intraday precision (RSD, 1.41-5.14%) and interday precision (RSD, 2.76-16.90%) were satisfactory. Compared with the conventional HPLC/MS method, a fast extraction and analysis procedure was applied and more flavonoids were detected in a single run. Additionally, 13 flavonoids in soybean seed were identified for the first time. The method was then applied to the profiling of six varieties of soybean sowed at the same place. A clear discrimination was observed among different cultivars, three isoflavones, accounting for nearly 80% of total flavonoid contents, were found increased in the spring soybeans compared with the summer cultivars. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Plasma L-ergothioneine measurement by high-performance liquid chromatography and capillary electrophoresis after a pre-column derivatization with 5-iodoacetamidofluorescein (5-IAF) and fluorescence detection.

PubMed

Sotgia, Salvatore; Pisanu, Elisabetta; Pintus, Gianfranco; Erre, Gian Luca; Pinna, Gerard Aime; Deiana, Luca; Carru, Ciriaco; Zinellu, Angelo

2013-01-01

Two sensitive and reproducible capillary electrophoresis and high-performance liquid chromatography-fluorescence procedures were established for quantitative determination of L-egothioneine in plasma. After derivatization of L-ergothioneine with 5-iodoacetamidofluorescein, the separation was carried out by HPLC on an ODS-2 C-18 sperisorb column by using a linear gradient elution and by HPCE on an uncoated fused silica capillary, 50 µm id, and 60 cm length. The methods were validated and found to be linear in the range of 0.3 to 10 µmol/l. The limit of quantification was 0.27 µmol/l for HPCE and 0.15 µmol/l for HPLC. The variations for intra- and inter-assay precision were around 6 RSD%, and the mean recovery accuracy close to 100% (96.11%).

Plasma L-Ergothioneine Measurement by High-Performance Liquid Chromatography and Capillary Electrophoresis after a Pre-Column Derivatization with 5-Iodoacetamidofluorescein (5-IAF) and Fluorescence Detection

PubMed Central

Sotgia, Salvatore; Pisanu, Elisabetta; Pintus, Gianfranco; Erre, Gian Luca; Pinna, Gerard Aime; Deiana, Luca; Carru, Ciriaco; Zinellu, Angelo

2013-01-01

Two sensitive and reproducible capillary electrophoresis and high-performance liquid chromatography-fluorescence procedures were established for quantitative determination of L-egothioneine in plasma. After derivatization of L-ergothioneine with 5-iodoacetamidofluorescein, the separation was carried out by HPLC on an ODS-2 C-18 sperisorb column by using a linear gradient elution and by HPCE on an uncoated fused silica capillary, 50 µm id, and 60 cm length. The methods were validated and found to be linear in the range of 0.3 to 10 µmol/l. The limit of quantification was 0.27 µmol/l for HPCE and 0.15 µmol/l for HPLC. The variations for intra- and inter-assay precision were around 6 RSD%, and the mean recovery accuracy close to 100% (96.11%). PMID:23922985

A validated high-performance liquid chromatographic method for the determination of glibenclamide in human plasma and its application to pharmacokinetic studies.

PubMed

Niopas, Ioannis; Daftsios, Athanasios C

2002-05-15

Glibenclamide is a potent second generation oral sulfonylurea antidiabetic agent widely used for the treatment of type II diabetes melitus. A rapid, sensitive, precise, accurate and specific HPLC assay for the determination of glibenclamide in human plasma was developed and validated. After addition of flufenamic acid as internal standard, the analytes were isolated from human plasma by liquid-liquid extraction. The method was linear in the 10-400 ng/ml concentration range (r > 0.999). Recovery for glibenclamide was greater than 91.5% and for internal standard was 93.5%. Within-day and between-day precision, expressed as the relative standard deviation (RSD%), ranged from 1.4 to 5.9% and 5.8 to 6.6%, respectively. Assay accuracy was better than 93.4%. The assay was used to estimate the pharmacokinetics of glibenclamide after oral administration of a 5 mg tablet of glibenclamide to 18 healthy volunteers.

Quality control of test iodine in urine by spectrophotometry UV-Vis

NASA Astrophysics Data System (ADS)

Huda, Thorikul; Nafisah, Durotun; Kumorowulan, Suryati; Lestari, Sri

2017-12-01

A quality control of iodine test in with UV-Vis spectrophotometry has been done. The purpose of this research is to find out whether the test results of samples conducted by Clinical Office of Research and Development Of GAKI (BP2GAKI) laboratory are still controlled, feasible and reliable, and still consistent over time, as indicated by the control chart. Quality control parameters are linearity, precision, accuracy, limit of detection, and limit of quantification. Based on the quality control that has been done, obtained linearity (r)= -0.9974, the detection limit and the limit of quantitation are respectively 2.26 µg/L and 7.54 µg/L, while the accuracy is calculated by %recovery and precision with value % RSD are 97.4161% and 1.7136% respectively. The quality control of iodine test in urine using the control chart shows excellent or stable results for 30 days and no variation of the results is very different for each day.

Determination of ractopamine and salbutamol in pig hair by liquid chromatography tandem mass spectrometry.

PubMed

Chang, Kai-Chun; Chang, Yu-Ting; Tsai, Chin-En

2018-04-01

A liquid chromatography tandem mass spectrometric method was developed for the determination of two β-agonists (ractopamine and salbutamol) in pig hair samples. An isotope of ractopamine-d5 or salbutamol-d6 as an internal standard was used to carry out quantitative analysis. Concentrated sodium hydroxide was used to pretreat hair samples and then purified by the solid phase extraction (SPE) procedure. The extracted solution was evaporated and reconstituted for injection in the instrument with electrospray ionization (ESI) operating in a positive multiple-reaction-monitoring (MRM) mode. Ractopamine and salbutamol separation were performed on C18 analytical column under gradient condition. The internal standard calibration curve was linear in the range of concentration from 0.5 to 100 ng mL -1  (R 2  > 0.995). Recoveries of this method estimated at three spiked concentrations of 100, 250 and 500 ng mL -1 in pig hair samples, were 79-82% for ractopamine and 77-96% for salbutamol. The corresponding inter-day and intra-day precisions expressed as relative standard deviation (RSD %) were 3.8-6.4% and 3.8-8.6%, respectively. The analytical time for one sample was 8 min. The detection limit of this method was 0.6 and 8.3 ng mL -1 for ractopamine and salbutamol, respectively. This developed method can be applied for monitoring the use of the β-agonists salbutamol and ractopamine in swine feed incurred pig hair. Copyright © 2017. Published by Elsevier B.V.

Magnetic ionic liquid aqueous two-phase system coupled with high performance liquid chromatography: A rapid approach for determination of chloramphenicol in water environment.

PubMed

Yao, Tian; Yao, Shun

2017-01-20

A novel organic magnetic ionic liquid based on guanidinium cation was synthesized and characterized. A new method of magnetic ionic liquid aqueous two-phase system (MILATPs) coupled with high-performance liquid chromatography (HPLC) was established to preconcentrate and determine trace amount of chloramphenicol (CAP) in water environment for the first time. In the absence of volatile organic solvents, MILATPs not only has the excellent properties of rapid extraction, but also exhibits a response to an external magnetic field which can be applied to assist phase separation. The phase behavior of MILATPs was investigated and phase equilibrium data were correlated by Merchuk equation. Various influencing factors on CAP recovery were systematically investigated and optimized. Under the optimal conditions, the preconcentration factor was 147.2 with the precision values (RSD%) of 2.42% and 4.45% for intra-day (n=6) and inter-day (n=6), respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.14ngmL -1 and 0.42ngmL -1 , respectively. Fine linear range of 12.25ngmL -1 -2200ngmL -1 was obtained. Finally, the validated method was successfully applied for the analysis of CAP in some environmental waters with the recoveries for the spiked samples in the acceptable range of 94.6%-99.72%. Hopefully, MILATPs is showing great potential to promote new development in the field of extraction, separation and pretreatment of various biochemical samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative determination and sampling of azathioprine residues for cleaning validation in production area.

PubMed

Fazio, Tatiana Tatit; Singh, Anil Kumar; Kedor-Hackmann, Erika Rosa Maria; Santoro, Maria Inês Rocha Miritello

2007-03-12

Cleaning validation is an integral part of current good manufacturing practices in any pharmaceutical industry. Nowadays, azathioprine and several other pharmacologically potent pharmaceuticals are manufactured in same production area. Carefully designed cleaning validation and its evaluation can ensure that residues of azathioprine will not carry over and cross contaminate the subsequent product. The aim of this study was to validate simple analytical method for verification of residual azathioprine in equipments used in the production area and to confirm efficiency of cleaning procedure. The HPLC method was validated on a LC system using Nova-Pak C18 (3.9 mm x 150 mm, 4 microm) and methanol-water-acetic acid (20:80:1, v/v/v) as mobile phase at a flow rate of 1.0 mL min(-1). UV detection was made at 280 nm. The calibration curve was linear over a concentration range from 2.0 to 22.0 microg mL(-1) with a correlation coefficient of 0.9998. The detection limit (DL) and quantitation limit (QL) were 0.09 and 0.29 microg mL(-1), respectively. The intra-day and inter-day precision expressed as relative standard deviation (R.S.D.) were below 2.0%. The mean recovery of method was 99.19%. The mean extraction-recovery from manufacturing equipments was 83.5%. The developed UV spectrophotometric method could only be used as limit method to qualify or reject cleaning procedure in production area. Nevertheless, the simplicity of spectrophotometric method makes it useful for routine analysis of azathioprine residues on cleaned surface and as an alternative to proposed HPLC method.

Simultaneous determination of D-aspartic acid and D-glutamic acid in rat tissues and physiological fluids using a multi-loop two-dimensional HPLC procedure.

PubMed

Han, Hai; Miyoshi, Yurika; Ueno, Kyoko; Okamura, Chieko; Tojo, Yosuke; Mita, Masashi; Lindner, Wolfgang; Zaitsu, Kiyoshi; Hamase, Kenji

2011-11-01

For a metabolomics study focusing on the analysis of aspartic and glutamic acid enantiomers, a fully automated two-dimensional HPLC system employing a microbore-ODS column and a narrowbore-enantioselective column was developed. By using this system, a detailed distribution of D-Asp and D-Glu besides L-Asp and L-Glu in mammals was elucidated. For the total analysis concept, the amino acids were first pre-column derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) to be sensitively and fluorometrically detected. For the non-stereoselective separation of the analytes in the first dimension a monolithic ODS column (750 mm × 0.53 mm i.d.) was adopted, and a self-packed narrowbore-Pirkle type enantioselective column (Sumichiral OA-2500S, 250 mm × 1.5 mm i.d.) was selected for the second dimension. In the rat plasma, RSD values for intra-day and inter-day precision were less than 6.8%, and the accuracy ranged between 96.1% and 105.8%. The values of LOQ of D-Asp and D-Glu were 5 fmol/injection (0.625 nmol/g tissue). The present method was successfully applied to the simultaneous determination of free aspartic acid and glutamic acid enantiomers in 7 brain areas, 11 peripheral tissues, plasma and urine of Wistar rats. Biologically significant D-Asp values were found in various tissue samples whereas for D-Glu the values were very low possibly indicating less significance. Copyright © 2011 Elsevier B.V. All rights reserved.

Simultaneous determination of linarin, naringenin and formononetin in rat plasma by LC-MS/MS and its application to a pharmacokinetic study after oral administration of Bushen Guchi Pill.

PubMed

Guo, Panpan; Dong, Lihua; Yan, Wenying; Wei, Jianceng; Wang, Chunying; Zhang, Zijian

2015-02-01

A sensitive and reproducible liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous determination of linarin, naringenin and formononetin in rat plasma after addition of sulfamethoxazole as the internal standard (IS). Separation was carried out on a Diamonsil C18 column (150 × 4.6 mm, 5 µm) with liner gradient elution using methanol (A) and 0.5‰ formic acid aqueous solution (B). Detection was performed on a triple-quadrupole linear ion trap mass spectrometer with the negative ion electrospray ionization in multiple-reaction monitoring (MRM) mode. The MRM transitions were m/z 591.2 → 283.2, 271.0 → 150.9, 266.9 → 252.0 and 252.0 → 155.9 for linarin, naringenin, formononetin and IS, respectively. All analytes showed good linearity within the concentration range (r > 0.9973). The lower limits of quantitation of linarin, naringenin and formononetin were 0.64, 1.07 and 1.04 ng/mL, respectively. Intra-day and inter-day precisions of the investigated components exhibited an RSD within 9.96%, and the accuracy (relative error) ranged from -11.25 to 9.38% at all quality control levels. The developed method was successfully applied to a pharmacokinetic study of linarin, naringenin and formononetin in rats after oral administration of Bushen Guchi Pill. Copyright © 2014 John Wiley & Sons, Ltd.

Simultaneous determination of 11 bioactive compounds in Jaeumganghwa-tang by high performance liquid chromatography-diode array detection

PubMed Central

Yun, Bo-Ra; Weon, Jin Bae; Lee, Jiwoo; Eom, Min Rye; Ma, Choong Je

2014-01-01

Background: Jaeumganghwa-tang (JEGH) is a traditional Korean herbal medicine for the treatment of chronic bronchitis, nephritis and diabetes mellitus. Objective: A high performance liquid chromatography-diode array detector (HPLC-DAD) method was developed for simultaneous determination of 11 major compounds such as 5- hydroxymethylfurfural, mangiferin, paeoniflorin, nodakenin, naringin, hesperidin, decursinol, berberine, glycyrrhizin, atractylenolide III and decursin, in JEGH. Materials and Methods: The separation was conducted on Shishedo C18 column with gradient elution of 0.1% trifluoroacetic acid–acetonitrile. Detection of wavelength was set at 205, 250, 280 and 330 nm. Results: The developed analysis showed a good linearity (R2 >0.9997). The range of limit of detection and limit of quantification were observed from 0.04 to 0.43 and from 0.11 to 1.30, respectively. The intra- and inter-day test relative standard deviations (RSD) were less than 3% and the accuracy was 95.98-108.44%. The recoveries were between 92.75% and 109.19% and RSD range of recoveries was measured from 0.52% to 2.78%. Conclusion: This HPLC-DAD method can be successfully applied for simultaneous determination of 11 major compounds in JEGH samples. PMID:24991100

Isotope dilution liquid chromatography-tandem mass spectrometry for simultaneous identification and quantification of beta-casomorphin 5 and beta-casomorphin 7 in yoghurt.

PubMed

Nguyen, D D; Solah, V A; Johnson, S K; Charrois, J W A; Busetti, F

2014-03-01

A highly selective and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous identification and quantification of beta-casomorphin 5 (BCM5) and beta-casomorphin 7 (BCM7) in yoghurt. The method used deuterium labelled BCM5-d10 and BCM7-d10 as surrogate standards for confident identification and accurate and quantification of these analytes in yoghurt. Linear responses for BCM5 and BCM7 (R(2)=0.9985 and 0.9986, respectively) was observed in the range 0.01-10ng/μL. The method limits of detection (MLDs) in yoghurt extracts were found to be 0.5 and 0.25ng/g for BCM5 and BCM7, respectively. Analyses of spiked samples were used to provide confirmation of accuracy and precision of the analytical method. Recoveries relative to the surrogate standards of these spikes were in the range of 95-106% for BCM5 and 103-109% for BCM7. Precision from analysis of spiked samples was expressed as relative standard deviation (%RSD) and values were in the range 1-16% for BCM5 and 1-6% for BCM7. Inter-day reproducibility was between 2.0-6.4% for BCM5 and between 3.2-6.1% for BCM7. The validated isotope dilution LC-MS/MS method was used to measure BCM5 and BCM7 in ten commercial and laboratory prepared samples of yoghurt and milk. Neither BCM5 nor BCM7 was detected in commercial yoghurts. However, they were observed in milk and laboratory prepared yoghurts and interestingly their levels decreased during processing. BCM5 decreased from 1.3ng/g in milk to 1.1ng/g in yoghurt made from that milk at 0day storage and

Salting-out assisted liquid-liquid extraction combined with capillary HPLC for the determination of sulfonylurea herbicides in environmental water and banana juice samples.

PubMed

Gure, Abera; Lara, Francisco J; Moreno-González, David; Megersa, Negussie; del Olmo-Iruela, Monsalud; García-Campaña, Ana M

2014-09-01

A salting-out assisted liquid-liquid extraction (SALLE) combined with capillary high performance liquid chromatography with diode array detector (capillary HPLC-DAD) was proposed for extraction and determination of residues of nine sulfonylurea herbicides (SUHs) in environmental water and banana juice samples. Various parameters affecting the extraction process such as the type and volume of the organic solvent, sample volume, type and amount of salt, pH of the sample and vortex time were optimized. Under optimum conditions, matrix matched calibration curves were established using river water and banana juice samples. Good linear relationships as well as low limits of detection, LODs (0.4-1.3 and 3-13 µg/L) and quantification, LOQs (1.3-4.3 and 10-43 µg/L) were obtained in water and banana juice samples, respectively. The precision (intra- and inter-day) of the peak areas expressed as relative standard deviations (%, RSD), at two concentration levels were below 10 % in both matrices. Recoveries obtained from spiked environmental waters (river water and groundwater) and banana juice samples, at two concentration levels, ranged from 72 to 115%. The results of the analysis revealed that the proposed SALLE-capillary HPLC method is simple, rapid, cheap and environmentally friendly, being successfully applicable for the determination of SUH residues in waters and banana juices. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous determination and pharmacokinetics of danshensu, protocatechuic aldehyde, 4-hydroxy-3-methyloxyphenyl lactic acid and protocatechuic acid in human plasma by LC-MS/MS after oral administration of Compound Danshen Dripping Pills.

PubMed

Li, Wei; Zhou, Hongjie; Chu, Yang; Wang, Xiangyang; Luo, Ruizhi; Yang, Liu; Polachi, Navaneethakrishnan; Li, Xiao; Chen, Min; Huang, Luqi; Yan, Xueying; Guo, Zhixin; Sun, He

2017-10-25

Compound Danshen Dripping Pills (CDDP), a herbal patent medicine, is widely used in China for the prevention and treatment of cardiovascular diseases. A simple, sensitive and reliable method for simultaneous determination of danshensu (DSS), protocatechuic aldehyde (PCA), and their related metabolites, 4-hydroxy-3-methyloxyphenyl lactic acid (HMLA) and protocatechuic acid (PAA) in human plasma was developed and validated based on liquid chromatography tandem mass spectrometry (LC-MS/MS). The analytes and internal standard (IS), vanillic acid (VAA), were extracted from plasma with ethyl acetate and separated on a C 18 column by using the mobile phase consisted of methanol-0.1% formic acid via gradient elution. The electrospray ionization (ESI) source was applied and operated under the multiple reaction monitoring (MRM) mode. The linear calibration curves were obtained at the concentration ranges of 0.46-1000ng/mL for DSS and PAA, and 1.38-1000ng/mL for PCA and HMLA, respectively. The inter- and intra-day precisions (RSD%) were less than 13.5%, and the accuracy (±RE%) was within 13.4%. The described method was successfully applied for the clinical pharmacokinetics of CDDP in Chinese healthy volunteers. Copyright © 2017. Published by Elsevier B.V.

Quantitative analysis of pyoluteorin in anti-fungal fermentation liquor of Pseudomonas species by capillary zone electrophoresis with UV-vis detector.

PubMed

Wang, Qiu-Ling; Zhang, Xue-Hong; Fan, Liu-Yin; Zhang, Wei; Xu, Yu-Qian; Hu, Hong-Bo; Cao, Cheng-Xi

2005-11-05

This paper investigated potential utility of capillary zone electrophoresis (CZE) for very succinct but robust quantitative analysis of pyoluteorin (Plt) in anti-fungal fermentation liquor of Pseudomonas species. The experimental conditions for the separation and quantification of Plt were optimized at first. The optimized conditions are: 80 mmol/L pH 8.40 Gly-NaOH buffer, 51 cm total length (42 cm effective) and 75 microm I.D. capillary, 230 nm wavelength, 25 kV, 13 mbar 10s pressure sample injection and 24 degrees C air-cooling. Under the optimized conditions, the migration times of Plt and the internal standard phenobarbital are 2.09 and 2.49 min, respectively, the linear response of Plt concentration ranges from 5.0 to 1000 microg/mL with high correlation coefficient (r=0.99977, n=9), the limits of detection (LOD) and quantification (LOQ) for Plt are 0.66 and 2.2 microg/mL, the precision values (expressed as R.S.D.) of intra- and inter-day are 1.19-1.94% and 1.55-6.21%, respectively, the recoveries of Plt at three concentration levels of 750, 250 and 50 microg/mL range from 90.31% to 97.85% and to 98.96%, respectively. The developed method can be well used for the quantification of Plt in the fermentation liquor.

Quantification of strontium in human serum by ICP-MS using alternate analyte-free matrix and its application to a pilot bioequivalence study of two strontium ranelate oral formulations in healthy Chinese subjects.

PubMed

Zhang, Dan; Wang, Xiaolin; Liu, Man; Zhang, Lina; Deng, Ming; Liu, Huichen

2015-01-01

A rapid, sensitive and accurate ICP-MS method using alternate analyte-free matrix for calibration standards preparation and a rapid direct dilution procedure for sample preparation was developed and validated for the quantification of exogenous strontium (Sr) from the drug in human serum. Serum was prepared by direct dilution (1:29, v/v) in an acidic solution consisting of nitric acid (0.1%) and germanium (Ge) added as internal standard (IS), to obtain simple and high-throughput preparation procedure with minimized matrix effect, and good repeatability. ICP-MS analysis was performed using collision cell technology (CCT) mode. Alternate matrix method by using distilled water as an alternate analyte-free matrix for the preparation of calibration standards (CS) was used to avoid the influence of endogenous Sr in serum on the quantification. The method was validated in terms of selectivity, carry-over, matrix effects, lower limit of quantification (LLOQ), linearity, precision and accuracy, and stability. Instrumental linearity was verified in the range of 1.00-500ng/mL, corresponding to a concentration range of 0.0300-15.0μg/mL in 50μL sample of serum matrix and alternate matrix. Intra- and inter-day precision as relative standard deviation (RSD) were less than 8.0% and accuracy as relative error (RE) was within ±3.0%. The method allowed a high sample throughput, and was sensitive and accurate enough for a pilot bioequivalence study in healthy male Chinese subjects following single oral administration of two strontium ranelate formulations containing 2g strontium ranelate. Copyright © 2014 Elsevier GmbH. All rights reserved.

Development and validation of a UPLC-MS method for the determination of galantamine in guinea pig plasma and its application to a pre-clinical bioavailability study of novel galantamine formulations.

PubMed

Wang, Jiang; Pavurala, Naresh; Xu, Xiaoming; Krishnaiah, Yellela S R; Faustino, Patrick J

2018-05-04

To evaluate the bioavailability and pharmacokinetic profiles of two novel galantamine formulations as medical countermeasure products, an ultra-performance liquid chromatography-single quadrupole mass spectrometry (UPLC-MS) method was developed and validated for quantifying galantamine in guinea pig plasma using solid-phase extraction with a mixed mode strong cation exchange reversed-phase cartridge. Chromatographic separation was achieved on a Waters Acquity UPLC BEH C 18 column maintained at 40°C. The mobile phases were solution A, acetonitrile-water, 5:95 (v/v) and solution B, acetonitrile-water 90:10 (v/v), both containing 2 mM ammonium formate and 0.2% formic acid. The mobile phase was delivered utilizing a 3 min gradient program start with 95%A-5%B at a flow rate of 0.6 mL/min. The analyte and internal standard, galantamine-d3, were detected by selected ion monitoring mode on a Waters 3100 single quadrupole mass spectrometer with positive electrospray ionization. The method was validated according to the US Food and Drug Administration bioanalytical guidance. The method was selective and was linear over the analytical range of 2-2000 ng/mL. Accuracy and precision were acceptable with intra- and inter-day accuracies between 96.8 and 101% and precisions (RSD) <4.88%. The method was successfully implemented to measure galantamine plasma levels in a series of pre-clinical bioavailability studies for the evaluation of novel galantamine formulations. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Headspace solid-phase microextraction coupled to gas chromatography-tandem mass spectrometry for the determination of haloanisoles in sparkling (cava and cider) and non-sparkling (wine) alcoholic beverages.

PubMed

Ruiz-Delgado, Ana; Arrebola-Liébanas, Francisco Javier; Romero-González, Roberto; López-Ruiz, Rosalía; Garrido Frenich, Antonia

2016-10-01

A highly sensitive analytical method was developed to determine 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), 2,4,6-tribromoanisole (TBA) and 2,3,4,5,6-pentachloroanisole (PCA) in sparkling alcoholic beverages. The method was based on the use of headspace solid-phase microextraction (HS-SPME) using a polydimethylsiloxane (PDMS) fibre. It was coupled to gas chromatography-triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS) for the detection and quantification of the target haloanisoles. The method was fully automated and no sample preparation was needed. The method was validated for alcoholic beverages. The influence of CO 2 on the extraction efficiency was also evaluated for the studied sparkling drinks (cava and cider). All the calibration curves showed good linearity (R 2  > 0.98) within the tested range (1-50 ng l -1 ). Recoveries were evaluated at three different levels (1, 5 and 50 ng l -1 ) and were always between 71% and 119%. Precision was expressed as relative standard deviation (RSD), and was evaluated as intra- and inter-day precisions, with values ≤ 22% in both cases. Limits of quantitation (LOQs) were ≤ 0.91 ng l -1 , which are below the sensory threshold levels for such compounds in humans. The validated method was applied to commercial samples, 10 cavas and 10 ciders, but it was also used for the analysis of nine red wines and four white wines, demonstrating the further applicability of the proposed method to non-sparkling beverages. TCA was detected in most samples at up to 0.45 ng l -1 .

Application of statistical experimental design to the optimisation of microextraction by packed sorbent for the analysis of nonsteroidal anti-inflammatory drugs in human urine by ultra-high pressure liquid chromatography.

PubMed

Magiera, Sylwia; Gülmez, Şefika; Michalik, Aleksandra; Baranowska, Irena

2013-08-23

A new approach based on microextraction by packed sorbent (MEPS) and a reversed-phase ultra-high pressure liquid chromatography (UHPLC) method was developed and validated for the determination and quantification of nonsteroidal anti-inflammatory drugs (NSAIDs) (acetylsalicylic acid, ketoprofen, diclofenac, naproxen and ibuprofen) in human urine. The important factors that could influence the extraction were previously screened using the Plackett-Burman design approach. The optimal MEPS extraction conditions were obtained using C18 phase as a sorbent, small sample volume (20μL) and a short time period (approximately 5min) for the entire sample preparation step. The analytes were separated on a core-shell column (Poroshell 120 EC-C18; 100mm×3.0mm; 2.7μm) using a binary mobile phase composed of aqueous 0.1% trifluoroacetic acid and acetonitrile in the gradient elution mode (4.5min of analysis time). The analytical method was fully validated based on linearity, limits of detection (LOD), limits of quantification (LOQ), inter- and intra-day precision and accuracy, and extraction yield. Under optimised conditions, excellent linearity (R(2)>0.9991), limits of detection (1.07-16.2ngmL(-1)) and precision (0.503-9.15% RSD) were observed for the target drugs. The average absolute recoveries of the analysed compounds extracted from the urine samples were 89.4-107%. The proposed method was also applied to the analysis of NSAIDs in human urine. The new approach offers an attractive alternative for the analysis of selected drugs from urine samples, providing several advantages including fewer sample preparation steps, faster sample throughput and ease of performance compared to traditional methodologies. Copyright © 2013 Elsevier B.V. All rights reserved.

Simple, fast and reliable liquid chromatographic and spectrophotometric methods for the determination of theophylline in urine, saliva and plasma samples.

PubMed

Charehsaz, Mohammad; Gürbay, Aylin; Aydin, Ahmet; Sahin, Gönül

2014-01-01

In this study, a high-performance liquid chromatographic method (HPLC) and UV spectrophotometric method were developed, validated and applied for the determination of theophylline in biological fluids. Liquid- liquid extraction is performed for isolation of the drug and elimination of plasma and saliva interferences. Urine samples were applied without any extraction. The chromatographic separation was achieved on a C18 column by using 60:40 methanol:water as mobile phase under isocratic conditions at a flow rate of 0.75 mL/min with UV detection at 280 nm in HPLC method. UV spectrophotometric analysis was performed at 275 nm. the limit of quantification: 1.1 µg/mL for urine, 1.9 µg/mL for saliva, 3.1 µg/mL for plasma; recovery: 94.85% for plasma, 100.45% for saliva, 101.39% for urine; intra-day precision: 0.22-2.33%, inter-day precision: 3.17-13.12%. Spectrophotometric analysis results were as follows: the limit of quantitation: 5.23 µg/mL for plasma, 8.7 µg/mL for urine; recovery: 98.27% for plasma, 95.25% for urine; intra-day precision: 2.37 - 3.00%, inter-day precision: 5.43-7.91%. It can be concluded that this validated HPLC method is easy, precise, accurate, sensitive and selective for determination of theophylline in biological samples. Also spectrophotometric analysis can be used where it can be applicable.

Investigation of material improvements to mitigate the abrasive wear mechanism of concrete crosstie rail seat deterioration (RSD).

DOT National Transportation Integrated Search

2014-11-01

To meet the increasingly stringent design and performance requirements due to increasing cumulative : gross tonnages from heavy-haul freight operations, along with increased high-speed inter-city passenger : rail development, improvements in concrete...

Characterising and correcting batch variation in an automated direct infusion mass spectrometry (DIMS) metabolomics workflow.

PubMed

Kirwan, J A; Broadhurst, D I; Davidson, R L; Viant, M R

2013-06-01

Direct infusion mass spectrometry (DIMS)-based untargeted metabolomics measures many hundreds of metabolites in a single experiment. While every effort is made to reduce within-experiment analytical variation in untargeted metabolomics, unavoidable sources of measurement error are introduced. This is particularly true for large-scale multi-batch experiments, necessitating the development of robust workflows that minimise batch-to-batch variation. Here, we conducted a purpose-designed, eight-batch DIMS metabolomics study using nanoelectrospray (nESI) Fourier transform ion cyclotron resonance mass spectrometric analyses of mammalian heart extracts. First, we characterised the intrinsic analytical variation of this approach to determine whether our existing workflows are fit for purpose when applied to a multi-batch investigation. Batch-to-batch variation was readily observed across the 7-day experiment, both in terms of its absolute measurement using quality control (QC) and biological replicate samples, as well as its adverse impact on our ability to discover significant metabolic information within the data. Subsequently, we developed and implemented a computational workflow that includes total-ion-current filtering, QC-robust spline batch correction and spectral cleaning, and provide conclusive evidence that this workflow reduces analytical variation and increases the proportion of significant peaks. We report an overall analytical precision of 15.9%, measured as the median relative standard deviation (RSD) for the technical replicates of the biological samples, across eight batches and 7 days of measurements. When compared against the FDA guidelines for biomarker studies, which specify an RSD of <20% as an acceptable level of precision, we conclude that our new workflows are fit for purpose for large-scale, high-throughput nESI DIMS metabolomics studies.

Comparison of in vivo 3D cone-beam computed tomography tooth volume measurement protocols.

PubMed

Forst, Darren; Nijjar, Simrit; Flores-Mir, Carlos; Carey, Jason; Secanell, Marc; Lagravere, Manuel

2014-12-23

The objective of this study is to analyze a set of previously developed and proposed image segmentation protocols for precision in both intra- and inter-rater reliability for in vivo tooth volume measurements using cone-beam computed tomography (CBCT) images. Six 3D volume segmentation procedures were proposed and tested for intra- and inter-rater reliability to quantify maxillary first molar volumes. Ten randomly selected maxillary first molars were measured in vivo in random order three times with 10 days separation between measurements. Intra- and inter-rater agreement for all segmentation procedures was attained using intra-class correlation coefficient (ICC). The highest precision was for automated thresholding with manual refinements. A tooth volume measurement protocol for CBCT images employing automated segmentation with manual human refinement on a 2D slice-by-slice basis in all three planes of space possessed excellent intra- and inter-rater reliability. Three-dimensional volume measurements of the entire tooth structure are more precise than 3D volume measurements of only the dental roots apical to the cemento-enamel junction (CEJ).

A multiple ion counter total evaporation (MICTE) method for precise analysis of plutonium by thermal ionization mass spectrometry

DOE PAGES

Inglis, Jeremy D.; Maassen, Joel; Kara, Azim; ...

2017-04-28

This study presents a total evaporation method for the analysis of sub-picogram quantities of Pu, utilizing an array of multiple ion counters. Data from three standards are presented to assess the utility of the technique. An external precision of 1.5% RSD (2σ) was achieved on aliquots approaching 100 fg for the minor 240Pu isotope. Accurate analysis of <1 femtogram of 240Pu, is achievable, with an external reproducibility of better than 10% RSD (2σ). Finally, this new technique represents a significant advance in the total evaporation method and will allow routine measurement of femtogram sized Pu samples by thermal ionization massmore » spectrometry.« less

A multiple ion counter total evaporation (MICTE) method for precise analysis of plutonium by thermal ionization mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inglis, Jeremy D.; Maassen, Joel; Kara, Azim

This study presents a total evaporation method for the analysis of sub-picogram quantities of Pu, utilizing an array of multiple ion counters. Data from three standards are presented to assess the utility of the technique. An external precision of 1.5% RSD (2σ) was achieved on aliquots approaching 100 fg for the minor 240Pu isotope. Accurate analysis of <1 femtogram of 240Pu, is achievable, with an external reproducibility of better than 10% RSD (2σ). Finally, this new technique represents a significant advance in the total evaporation method and will allow routine measurement of femtogram sized Pu samples by thermal ionization massmore » spectrometry.« less

Renal sympathetic denervation improves rate control in patients with symptomatic persistent atrial fibrillation and hypertension.

PubMed

Qiu, Min; Shan, Qijun; Chen, Chun; Geng, Jie; Guo, Jiqun; Zhou, Xiujuan; Qian, Weichong; Tang, Lijun; Yin, Yuehui

2016-02-01

The aim of this study was to investigate whether renal sympathetic denervation (RSD) improves ventricular heart rate (HR) control in patients with persistent atrial fibrillation (AF). Twenty-one patients (aged 57.5 ± 10.2 years, 76.2% male) with persistent AF and hypertension underwent RSD and completed 7-days follow-up evaluations, including 24-hour Holter monitoring (Holter), blood pressure (BP), 24-hour ambulatory BP monitoring (ABPM). Patients were grouped into tertiles of average HR at baseline Holter recording for evaluation of RSD effects on atrioventricular (AV) node (group 1: HR ≧ 90 bpm; group 2: 80 bpm ≦ HR < 90 bpm; group 3: HR < 80 bpm). All patients successfully underwent RSD without any complications. The clinical and procedural characteristics were similar in all groups of patients. No significant changes in BP were observed in the three groups before and after RSD. Compared with baseline, the average HR (Holter) of patients in group 1, 2 and 3 had a reduction of 22.6 ± 13.2 bpm (83.3 ± 4.9 vs 106.0 ± 14.6, P = 0.004), 9.7 ± 7.8 bpm (75.7 ± 7.6 vs 85.4 ± 3.7, P = 0.017) and 2.3 ± 2.9 bpm (71.4 ± 4.0 vs 73.7 ± 4.7, P = 0.089) at 7 days after RSD, respectively. RSD could improve ventricular HR control in patients with persistent AF. RSD slowed AV node conduction in baseline HR-dependent manner. RSD may become an alternative non-pharmaceutical tool for rate control in patients with persistent AF.

Very fast electrophoretic determination of creatinine and uric acid in human urine using a combination of two capillaries with different internal diameters.

PubMed

Pavlíček, Václav; Tůma, Petr; Matějčková, Jana; Samcová, Eva

2014-04-01

A capillary system formed by combining 25 and 100 μm id capillaries was used in the short-end injection mode to determine creatinine and uric acid in human urine. The separation was performed at an electric field intensity of 2.3 kV/cm. Creatinine was determined in a BGE with a composition of 20 mM citric acid/NaOH (pH 3.0), and uric acid was determined in 20 mM MES/NaOH (pH 6.0). Under these conditions, migration times of 12.2 s for creatinine and 8.6 s for uric acid were achieved. The LOD value is 2.4 mg/L for creatinine and 0.9 mg/L for uric acid; the RSD for the migration time varies in the range 0.7-1.1% (intra day) to 1.0-7.5% (inter day); RSDs for the peak areas equalled 3.4-4.0% (intra day) and 4.3-4.7% (inter day). The determined creatinine values in seven urine samples vary in the range 221-1394 mg/L for creatinine and 87-615 mg/L for uric acid. t-Test did not reveal any statistically significant difference between the developed CE methodologies and reference methods - Jaffé reaction for creatinine and enzymatic uricase test for uric acid. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A fabric phase sorptive extraction-High performance liquid chromatography-Photo diode array detection method for the determination of twelve azole antimicrobial drug residues in human plasma and urine.

PubMed

Locatelli, Marcello; Kabir, Abuzar; Innosa, Denise; Lopatriello, Teresa; Furton, Kenneth G

2017-01-01

This paper reports a novel fabric phase sorptive extraction-high performance liquid chromatography-photodiode array detection (FPSE-HPLC-PDA) method for the simultaneous extraction and analysis of twelve azole antimicrobial drug residues that include ketoconazole, terconazole, voriconazole, bifonazole, clotrimazole, tioconazole, econazole, butoconazole, miconazole, posaconazole, ravuconazole, and itraconazole in human plasma and urine samples. The selected azole antimicrobial drugs were well resolved by using a Luna C 18 column (250mm×4.6mm; 5μm particle size) in gradient elution mode within 36min. The analytical method was calibrated and validated in the range from 0.1 to 8μg/mL for all the drug compounds. Blank human plasma and urine were used as the sample matrix for the analysis; while benzyl-4-hydroxybenzoate was used as the internal standard (IS). The limit of quantification of the FPSE-HPLC-PDA method was found as 0.1μg/mL and the weighted-matrix matched standard calibration curves of the drugs showed a good linearity upto a concentration of 8μg/mL. The parallelism tests were also performed to evaluate whether overrange sample can be analyzed after dilution, without compromising the analytical performances of the validated method. The intra- and inter-day precision (RSD%) values were found ≤13.1% and ≤13.9%, respectively. The intra- and inter-day trueness (bias%) values were found in the range from -12.1% to 10.5%. The performances of the validated FPSE-HPLC-PDA were further tested on real samples collected from healthy volunteers after a single dose administration of itraconazole and miconazole. To the best of our knowledge, this is the first FPSE extraction procedure applied on plasma and urine samples for the simultaneous determination of twelve azole drugs possessing a wide range of logK ow values (extending from 0.4 for fluconazole to 6.70 of butoconazole) and could be adopted as a rapid and robust green analytical tool for clinical and pharmaceutical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

A validated fast difference spectrophotometric method for 5-hydroxymethyl-2-furfural (HMF) determination in corn syrups.

PubMed

de Andrade, Jucimara Kulek; de Andrade, Camila Kulek; Komatsu, Emy; Perreault, Hélène; Torres, Yohandra Reyes; da Rosa, Marcos Roberto; Felsner, Maria Lurdes

2017-08-01

Corn syrups, important ingredients used in food and beverage industries, often contain high levels of 5-hydroxymethyl-2-furfural (HMF), a toxic contaminant. In this work, an in house validation of a difference spectrophotometric method for HMF analysis in corn syrups was developed using sophisticated statistical tools by the first time. The methodology showed excellent analytical performance with good selectivity, linearity (R 2 =99.9%, r>0.99), accuracy and low limits (LOD=0.10mgL -1 and LOQ=0.34mgL -1 ). An excellent precision was confirmed by repeatability (RSD (%)=0.30) and intermediate precision (RSD (%)=0.36) estimates and by Horrat value (0.07). A detailed study of method precision using a nested design demonstrated that variation sources such as instruments, operators and time did not interfere in the variability of results within laboratory and consequently in its intermediate precision. The developed method is environmentally friendly, fast, cheap and easy to implement resulting in an attractive alternative for corn syrups quality control in industries and official laboratories. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ropivacaine and Bupivacaine prevent increased pain sensitivity without altering neuroimmune activation following repeated social defeat stress.

PubMed

Sawicki, Caroline M; Kim, January K; Weber, Michael D; Jarrett, Brant L; Godbout, Jonathan P; Sheridan, John F; Humeidan, Michelle

2018-03-01

Mounting evidence indicates that stress influences the experience of pain. Exposure to psychosocial stress disrupts bi-directional communication pathways between the central nervous system and peripheral immune system, and can exacerbate the frequency and severity of pain experienced by stressed subjects. Repeated social defeat (RSD) is a murine model of psychosocial stress that recapitulates the immune and behavioral responses to stress observed in humans, including activation of stress-reactive neurocircuitry and increased pro-inflammatory cytokine production. It is unclear, however, how these stress-induced neuroimmune responses contribute to increased pain sensitivity in mice exposed to RSD. Here we used a technique of regional analgesia with local anesthetics in mice to block the development of mechanical allodynia during RSD. We next investigated the degree to which pain blockade altered stress-induced neuroimmune activation and depressive-like behavior. Following development of a mouse model of regional analgesia with discrete sensory blockade over the dorsal-caudal aspect of the spine, C57BL/6 mice were divided into experimental groups and treated with Ropivacaine (0.08%), Liposomal Bupivacaine (0.08%), or Vehicle (0.9% NaCl) prior to exposure to stress. This specific region was selected for analgesia because it is the most frequent location for aggression-associated pain due to biting during RSD. Mechanical allodynia was assessed 12 h after the first, third, and sixth day of RSD after resolution of the sensory blockade. In a separate experiment, social avoidance behavior was determined after the sixth day of RSD. Blood, bone marrow, brain, and spinal cord were collected for immunological analyses after the last day of RSD in both experiments following behavioral assessments. RSD increased mechanical allodynia in an exposure-dependent manner that persisted for at least one week following cessation of the stressor. Mice treated with either Ropivacaine or Liposomal Bupivacaine did not develop mechanical allodynia following exposure to stress, but did develop social avoidance behavior. Neither drug affected stress-induced activation of monocytes in the bone marrow, blood, or brain. Neuroinflammatory responses developed in all treatment groups, as evidenced by elevated IL-1β mRNA levels in the brain and spinal cord after RSD. In this study, psychosocial stress was associated with increased pain sensitivity in mice. Development of mechanical allodynia with RSD was blocked by regional analgesia with local anesthetics, Ropivacaine or Liposomal Bupivacaine. Despite blocking mechanical allodynia, these anesthetic interventions did not prevent neuroimmune activation or social avoidance associated with RSD. These data suggest that stress-induced neuroinflammatory changes are not associated with increased sensitivity to pain following RSD. Thus, blocking peripheral nociception was effective in inhibiting enhanced pain signaling without altering stress-induced immune or behavioral responses. Copyright © 2017 Elsevier Inc. All rights reserved.

Characterization, thermal stability studies, and analytical method development of Paromomycin for formulation development.

PubMed

Khan, Wahid; Kumar, Neeraj

2011-06-01

Paromomycin (PM) is an aminoglycoside antibiotic, first isolated in the 1950s, and approved in 2006 for treatment of visceral leishmaniasis. Although isolated six decades back, sufficient information essential for development of pharmaceutical formulation is not available for PM. The purpose of this paper was to determine thermal stability and development of new analytical method for formulation development of PM. PM was characterized by thermoanalytical (DSC, TGA, and HSM) and by spectroscopic (FTIR) techniques and these techniques were used to establish thermal stability of PM after heating PM at 100, 110, 120, and 130 °C for 24 h. Biological activity of these heated samples was also determined by microbiological assay. Subsequently, a simple, rapid and sensitive RP-HPLC method for quantitative determination of PM was developed using pre-column derivatization with 9-fluorenylmethyl chloroformate. The developed method was applied to estimate PM quantitatively in two parenteral dosage forms. PM was successfully characterized by various stated techniques. These techniques indicated stability of PM for heating up to 120 °C for 24 h, but when heated at 130 °C, PM is liable to degradation. This degradation is also observed in microbiological assay where PM lost ∼30% of its biological activity when heated at 130 °C for 24 h. New analytical method was developed for PM in the concentration range of 25-200 ng/ml with intra-day and inter-day variability of < 2%RSD. Characterization techniques were established and stability of PM was determined successfully. Developed analytical method was found sensitive, accurate, and precise for quantification of PM. Copyright © 2010 John Wiley & Sons, Ltd. Copyright © 2010 John Wiley & Sons, Ltd.

Development of an UPLC-MS/MS method for quantification of Avitinib (AC0010) and its five metabolites in human cerebrospinal fluid: Application to a study of the blood-brain barrier penetration rate of non-small cell lung cancer patients.

PubMed

Wang, Weicong; Zheng, Xin; Wang, Hanping; Wang, Lu; Jiang, Ji; Hu, Pei

2017-05-30

Avitinib (AC0010) is a mutant-selective epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI), designed to be a targeted therapeutic agent for non-small cell lung cancer (NSCLC) patients harboring EGFR active and T790M resistant mutations. A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination of Avitinib and its five metabolites (M1, M2, M4, M7, MII-6) in human cerebrospinal fluid (CSF). The samples were purified by protein precipitation and separated on a BEH C 18 column (2.1×50mm, 1.7μm). Electrospray ionization (ESI) in positive ion mode and multiple reaction monitoring (MRM) were used to monitor the ion transitions at m/z 488/257, 474/403, 504/487, 434/377, 490/405, 476/391. The results indicated that the method had excellent sensitivity and specificity. The linear range covered from 0.05 to 50ng/mL for Avitinib, M1, M4, M7, and MII-6, and from 0.01 to 10ng/mL for M2. Intra-day and inter-day precisions (in terms of% RSD) were all <15% and the accuracies (in terms of% RE) were within the range of ±15%. The lower limit of quantification (LLOQ), matrix effect, extraction recovery, stability and dilution integrity were also validated and satisfied with the criteria of validation. Finally, the method was successfully applied to a blood-brain barrier (BBB) penetration rate research of NSCLC patients after an oral administration of Avitinib. Copyright © 2017. Published by Elsevier B.V.

Quantitative determination of hederagenin in rat plasma and cerebrospinal fluid by ultra fast liquid chromatography-tandem mass spectrometry method.

PubMed

Yang, Xuemei; Li, Guoliang; Chen, Lingyun; Zhang, Cong; Wan, Xinxiang; Xu, Jiangping

2011-07-01

A rapid, sensitive and selective method was developed for the quantitative determination of hederagenin in rat plasma and cerebrospinal fluid (CSF) by ultra fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS). It has been successfully applied in a pharmacokinetic study of hederagenin in the central nervous system (CNS). Sample pretreatment involved a simple protein precipitation with methanol and a one-step extraction with ethyl acetate. Separation was carried out in a Shim-pack XR-ODS II (75 mm × 2.0 mm, i.d., 2.1 μm) column with gradient elution at a flow rate of 0.35 mL/min. The mobile phase was 5mM ammonium acetate and acetonitrile. Detection was performed in a triple-quadruple tandem mass spectrometer by multiple-reaction-monitoring mode via electrospray ionization. A linear calibration curve for hederagenin was obtained over a concentration range of 0.406 (lower limit of quantification, LLOQ) to 203 ng/mL (r² > 0.99) for both plasma and CSF. The intra-day and inter-day precision (relative standard deviation, RSD) values were less than 15%. At all quality control (QC) levels, the accuracy (relative error, RE) was within -9.0% and 11.1% for plasma and CSF, respectively. The pharmacokinetics results indicated that hederagenin could pass through the blood-brain barrier. This UFLC-MS/MS method demonstrates higher sensitivity and sample throughput than previous methods. It was also successfully applied to the pharmacokinetic study of hederagenin following oral administration of Fructus akebiae extract in rats. Copyright © 2011 Elsevier B.V. All rights reserved.

Analysis of anabolic androgenic steroids in urine by full-capillary sample injection combined with a sweeping CE stacking method.

PubMed

Wang, Chun-Chi; Cheng, Shu-Fang; Cheng, Hui-Ling; Chen, Yen-Ling

2013-02-01

This study describes an on-line stacking CE approach by sweeping with whole capillary sample filling for analyzing five anabolic androgenic steroids in urine samples. The five anabolic steroids for detection were androstenedione, testosterone, epitestosterone, boldenone, and clostebol. Anabolic androgenic steroids are abused in sport doping because they can promote muscle growth. Therefore, a sensitive detection method is imperatively required for monitoring the urine samples of athletes. In this research, an interesting and reliable stacking capillary electrophoresis method was established for analysis of anabolic steroids in urine. After liquid-liquid extraction by n-hexane, the supernatant was dried and reconstituted with 30 mM phosphate buffer (pH 5.00) and loaded into the capillary by hydrodynamic injection (10 psi, 99.9 s). The stacking and separation were simultaneously accomplished at -20 kV in phosphate buffer (30 mM, pH 5.0) containing 100 mM sodium dodecyl sulfate and 40 % methanol. During the method validation, calibration curves were linear (r≥0.990) over a range of 50-1,000 ng/mL for the five analytes. In the evaluation of precision and accuracy for this method, the absolute values of the RSD and the RE in the intra-day (n=3) and inter-day (n=5) analyses were all less than 6.6 %. The limit of detection for the five analytes was 30 ng/mL (S/N=5, sampling 99.9 s at 10 psi). Compared with simple MECK, this stacking method possessed a 108- to 175-fold increase in sensitivity. This simple and sensitive stacking method could be used as a powerful tool for monitoring the illegal use of doping.

Simultaneous determination of cucurbitacin B and cucurbitacin E in rat plasma by UHPLC-MS/MS: A pharmacokinetics study after oral administration of cucurbitacin tablets.

PubMed

Wang, Zhibin; Zhu, Wenbo; Gao, Mingjie; Wu, Chengcui; Yang, Chunjuan; Yang, Jing; Wu, Gaosong; Yang, Bingyou; Kuang, Haixue

2017-10-15

Cucurbitacin B (CuB) and cucurbitacin E (CuE) are tetracyclic triterpene compounds from Cucurbitaceae, and the main bioactive compounds of cucurbitacins tablets that used to treatment of chronic hepatitis. Pharmacological research has been very comprehensive, and there are few studies on pharmacokinetics, especially about CuE. An Ultra High Performance Liquid Chromatography-tandem Mass Spectrometry (UHPLC-MS/MS) method with high selectivity, simplicity and sensitivity has been used for quantitative analysis of Cucurbitacin B (CuB) and cucurbitacin E (CuE). Plasma samples were pretreatment by Liquid-liquid extraction (LLE) method with dichloromethane. The chromatographic separation was achieved on a C 18 column (Agilent Eclipse Plus, 1.8μm, 50×2.1mm) using gradient elution with water - methanol at a flow rate of 0.3mL/min and the column temperature was set at 30°C. The method was validated according to FDA guidelines. Lower limit of quantification (LLOQ) was 1.60ng/mL for CuB and 1.58ng/mL for CuE. Correlation coefficients of CuB and CuE were more than 0.99 in rat plasma. All values of intra-day and inter-day precision (RSD%) were not exceeded 15%, the accuracy (RE%) were within -5.57 to 5.20% for CuB and -3.33 to 7.37% for CuE. The mean extraction recoveries were more than 80%. Pharmacokinetic parameters were also evaluated by UHPLC-MS/MS method. The results suggestion that this method was successfully applied to pharmacokinetic study of CuB and CuE in rat plasma after oral administration cucurbitacin tablets. Published by Elsevier B.V.

Equivalence-point electromigration acid-base titration via moving neutralization boundary electrophoresis.

PubMed

Yang, Qing; Fan, Liu-Yin; Huang, Shan-Sheng; Zhang, Wei; Cao, Cheng-Xi

2011-04-01

In this paper, we developed a novel method of acid-base titration, viz. the electromigration acid-base titration (EABT), via a moving neutralization boundary (MNR). With HCl and NaOH as the model strong acid and base, respectively, we conducted the experiments on the EABT via the method of moving neutralization boundary for the first time. The experiments revealed that (i) the concentration of agarose gel, the voltage used and the content of background electrolyte (KCl) had evident influence on the boundary movement; (ii) the movement length was a function of the running time under the constant acid and base concentrations; and (iii) there was a good linearity between the length and natural logarithmic concentration of HCl under the optimized conditions, and the linearity could be used to detect the concentration of acid. The experiments further manifested that (i) the RSD values of intra-day and inter-day runs were less than 1.59 and 3.76%, respectively, indicating similar precision and stability in capillary electrophoresis or HPLC; (ii) the indicators with different pK(a) values had no obvious effect on EABT, distinguishing strong influence on the judgment of equivalence-point titration in the classic one; and (iii) the constant equivalence-point titration always existed in the EABT, rather than the classic volumetric analysis. Additionally, the EABT could be put to good use for the determination of actual acid concentrations. The experimental results achieved herein showed a new general guidance for the development of classic volumetric analysis and element (e.g. nitrogen) content analysis in protein chemistry. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous Determination of Acetaminophen and Synthetic Color(s) by Derivative Spectroscopy in Syrup Formulations and Validation by HPLC: Exposure Risk of Colors to Children.

PubMed

Rastogi, Shanya Das; Dixit, Sumita; Tripathi, Anurag; Das, Mukul

2015-06-01

Color additives are used in pediatric syrup formulations as an excipient; though not pre-requisite, but pediatric syrup formulations are normally colored. An attempt has been made to measure simultaneously the single drug, acetaminophen (AT), along with the colors, carmoisine (CA), erythrosine (ET), and sunset yellow FCF (SSY) added in it by three derivative spectroscopy methods namely, 1st order, ratio, and differential derivative methods. Moreover, evaluation has been made for the exposure assessment of the colors added as excipient because some colors have been reported to cause allergic reactions and hypersensitivity in children. The present methods provide simple, accurate, and reproducible quantitative determination of the drug, AT, along with the color in synthetic mixtures and commercial drug formulations without any interference. The limit of detection varied from 0.0001-0.31 μg/ml while limit of quantification ranged from 0.002-1.04 μg/ml in all the three methods. The calibration curve of all the three derivative methods exhibited good linear relationship with excellent regression coefficients (0.9986-1.000). Both intra-day and inter-day precisions showed %RSD value less than 2% while the percentage recovery was found between 96.8-103.8%. The sensitivity of the proposed methods is almost comparable to HPLC and thus, can be used for determination of drug AT, and color simultaneously in pharmaceutical formulation on routine basis. The present methods also showed that colors like SSY and ET are saturating more than 50% of acceptable daily intake (ADI) value which is alarming and needs to be considered for modification by regulatory authorities to safeguard the health of children.

Extensive intestinal first-pass metabolism of arctigenin: evidenced by simultaneous monitoring of both parent drug and its major metabolites.

PubMed

Gao, Qiong; Zhang, Yufeng; Wo, Siukwan; Zuo, Zhong

2014-03-01

The current study aims to investigate intestinal absorption and metabolism of arctigenin (AR) through simultaneous monitoring of AR and its major metabolites in rat plasma. An UPLC/MS/MS assay was developed with chromatographic separation of all analytes achieved by a C18 Column (3.9mm×150mm, 3.5μm) and a gradient elution with acetonitrile and 0.1% formic acid within 9min. Sample extraction with acetonitrile was optimized to achieve satisfactory recovery for both AR and its major metabolites. The lower limit of quantification (LLOQ) for all analytes was 25ng/ml. The intra-day and inter-day precision and accuracy of each analyte at LLOQ and three quality control (QC) concentrations (low, middle and high) in rat plasma was within 15.0% RSD and 15.0% bias. The extraction recoveries were within the range of 83.8-94.0% for all analytes. The developed and validated assay was then applied to the absorption study of AR in both Caco-2 cell monolayer model and in situ single-pass rat intestinal perfusion model. High absorption permeability of AR was demonstrated in both models with Papp of (1.76±0.48)×10(-5) (A→B) (Caco-2) and Pblood of (8.6±3.0)×10(-6)cm/s (intestinal perfusion). Extensive first-pass metabolism of AR to arctigenic acid (AA) and arctigenin-4'-O-glucuronide (AG) was identified in rat intestinal perfusion study with Cummins's extraction ratios of 0.458±0.012 and 0.085±0.013, respectively. The current assay method demonstrated to be a practical tool for pharmacokinetics investigation of AR with complicated metabolism pathways and multiple metabolites. Copyright © 2013 Elsevier B.V. All rights reserved.

[Determination of diborane in the air of workplace by ICP-AES].

PubMed

Ding, Chun-Guang; Zhang, Jing; Yan, Hui-Fang

2011-06-01

A sampling method was established to collect diborane in the air of workplace and an ICP-AES method was developed to determine the Boron in desorbed solution. Diborane in the air of workplace was collected by solid sorbent tube filled with oxidant impregnated activated carbon. The adsorbed diborane was desorbed into 3% H2O2 aqueous, and then the desorbed Boron was determined by ICP-AES. The sampling efficiency of this method was 99.6% with the desorption efficiency of diborane with 5.660 microg and 56.6 microg spiked were 90.9% and 99.5%, respectively. Both the intra-and inter-precision RSD were less than 8%. The standard curve of this method ranged from 0.1 to 10.0 microg/ml (Boron), and the LOD and LOQ were 0.011 mg/m3 and 0.035 mg/m3 (15L samples) respectively. The method established was suitable for diborane sampling and determination in the air of workplace.

Molecular weight distribution of polysaccharides from edible seaweeds by high-performance size-exclusion chromatography (HPSEC).

PubMed

Gómez-Ordóñez, Eva; Jiménez-Escrig, Antonio; Rupérez, Pilar

2012-05-15

Biological properties of polysaccharides from seaweeds are related to their composition and structure. Many factors such as the kind of sugar, type of linkage or sulfate content of algal biopolymers exert an influence in the relationship between structure and function. Besides, the molecular weight (MW) also plays an important role. Thus, a simple, reliable and fast HPSEC method with refractive index detection was developed and optimized for the MW estimation of soluble algal polysaccharides. Chromatogram shape and repeatability of retention time was considerably improved when sodium nitrate was used instead of ultrapure water as mobile phase. Pullulan and dextran standards of different MW were used for method calibration and validation. Also, main polysaccharide standards from brown (alginate, fucoidan, laminaran) and red seaweeds (kappa- and iota-carrageenan) were used for quantification and method precision and accuracy. Relative standard deviation (RSD) of repeatability for retention time, peak areas and inter-day precision was below 0.7%, 2.5% and 2.6%, respectively, which indicated good repeatability and precision. Recoveries (96.3-109.8%) also showed its fairly good accuracy. Regarding linearity, main polysaccharide standards from brown or red seaweeds showed a highly satisfactory correlation coefficient (r>0.999). Moreover, a good sensitivity was shown, with corresponding limits of detection and quantitation in mg/mL of 0.05-0.21 and 0.16-0.31, respectively. The method was applied to the MW estimation of standard algal polysaccharides, as well as to the soluble polysaccharide fractions from the brown seaweed Saccharina latissima and the red Mastocarpus stellatus, respectively. Although distribution of molecular weight was broad, the good repeatability for retention time provided a good precision in MW estimation of polysaccharides. Water- and alkali-soluble fractions from S. latissima ranged from very high (>2400 kDa) to low MW compounds (<6 kDa); this high heterogeneity could be attributable to the complex polysaccharide composition of brown algae. Regarding M. stellatus, sulfated galactans followed a descending order of MW (>1400 kDa to <10 kDa), related to the different solubility of carrageenans in red seaweeds. In summary, the method developed allows for the molecular weight analysis of seaweed polysaccharides with very good precision, accuracy, linearity and sensitivity within a short time. Copyright © 2012 Elsevier B.V. All rights reserved.

Quantitative analysis of flavonoids, alkaloids and saponins of Banxia Xiexin decoction using ultra-high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

PubMed

Wang, Ying; Xu, Ranchi; Xiao, Juan; Zhang, Jian; Wang, Xinhong; An, Rui; Ma, Yueming

2014-01-01

Banxia Xiexin decoction (BXD) is an effective Chinese Medicinal Prescription in treating gastroenteritis diseases. In this study an ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to separate and determine 18 major active ingredients of BXD in order to guarantee quality. The separation of ten flavonoids, four alkaloids and four saponins was accomplished on an Acquity BEH C18 (2.1mm×100mm, 1.7μm) column using gradient elution with 0.1% (v/v) formic acid water (A) and 0.1% (v/v) formic acid in methanol (B). All the analytes were detected in positive electrospray ionization tandem mass spectrometry by selective reaction monitoring (SRM) mode. A good linear regression relationship for each analyte was obtained over the range from 2.41-438ng/ml to 20.75-4150ng/ml. The precision was evaluated by intra- and inter-day assays with relative standard deviation (RSD) less than 7.7%. The recovery measured at three concentration levels varied from 92.4% to 107.8%. The method sensitivity expressed as LOQ was typically 0.97-4.15ng/ml. The assay was successfully applied for determination of the 18 bioactive compounds in BXD. The results indicated that the new UPLC-MS/MS method was rapid and accurate, and could be reliably utilized as a quality control method for BXD. Copyright © 2013 Elsevier B.V. All rights reserved.

Simultaneous determination of acetylpuerarin and puerarin in rat plasma by liquid chromatography-tandem mass spectrometry: Application to a pharmacokinetic study following intravenous and oral administration.

PubMed

Sun, Deqing; Xue, Aiying; Wu, Jing; Zhang, Bin; Yu, Jinlong; Li, Qiang; Sun, Chao

2015-07-15

A rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the simultaneous determination of acetylpuerarin (AP) and its major metabolite puerarin (PUE) in rat plasma using genistein as the internal standard (IS). Plasma samples were pretreated by protein precipitation with a mixture of methanol and acetonitrile. Chromatographic separation was performed on a CAPCELL PAK C18 MGШ column with a mixture of 0.1% formic acid in water and methanol (35:65, v/v) as the mobile phase. The analytes were detected using a tandem mass spectrometer in the positive ionization and multiple-reaction monitoring mode. The ion transition of m/z 669.4→627.3, 417.5→297.6 and 271.3→153.0 was utilized to quantify AP, PUE and the IS, respectively. The calibration curves showed good linearity over the plasma concentration range of 1-2000ng/mL for AP and 2.5-5000ng/mL for PUE. The intra- and inter-day precisions (RSD %) for each analyte were less than 6.91%, and the accuracies ranged from -2.17% to 2.93%. The validated LC-MS/MS method was further successfully applied to a pharmacokinetic study of AP and PUE in rats following intravenous and oral administration. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous quantification of paeoniflorin, nobiletin, tangeretin, liquiritigenin, isoliquiritigenin, liquiritin and formononetin from Si-Ni-San extract in rat plasma and tissues by liquid chromatography-tandem mass spectrometry.

PubMed

Li, Tianxue; Yan, Zhixiang; Zhou, Chen; Sun, Jian; Jiang, Chuan; Yang, Xinghao

2013-08-01

In this study, a sensitive and reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of seven bioactive components including paeoniflorin, nobiletin, tangeretin, liquiritigenin, isoliquiritigenin, liquiritin and formononetin in rat plasma and tissues after oral administration of Si-Ni-San extract using astragaloside IV as internal standard (IS). The plasma and tissue samples were extracted by solid-phase extraction. Chromatographic separation was accomplished on a C18 column with a multiple-step gradient elution. The quantification was obtained by scanning with multiple reaction monitoring via an electrospray ionization source that was operated by switching between the positive and negative modes in two MS/MS scan segments. Full validation of the assay was implemented. In conclusion, this method demonstrated good linearity and specificity. The lower limits of quantification for the analytes were <7.5 ng/mL. Intra- and inter-day precisions (RSD) were <12.5% and accuracy (RE) ranged from -10.2 to 7.3%. The average recoveries of the analytes from rat plasma and tissues were >65.2% and 58.6%, respectively. The validated method was further applied to the determination of actual rat plasma and tissues after oral administration of Si-Ni-San extract. The results provided a meaningful basis for the clinical application of this prescription. Copyright © 2013 John Wiley & Sons, Ltd.

UHPLC-ESI-MS/MS determination and pharmacokinetics of pinoresinol glucoside and chlorogenic acid in rat plasma after oral administration of Eucommia ulmoides Oliv extract.

PubMed

Gong, Xiaojian; Luan, Qingxiang; Zhou, Xin; Zhao, Yang; Zhao, Chao

2017-11-01

This study aimed to develop a specific UHPLC-ESI-MS/MS method for simultaneous determination and pharmacokinetics of pinoresinol glucoside and chlorogenic acid in rat plasma after oral administration of Eucommia ulmoides. The chromatographic separation was achieved on a Hypersil GOLD column with gradient elution by using a mixture of 0.1% formic acid aqueous solution and acetonitrile as the mobile phase at a flow rate of 200 μL/min. A tandem mass spectrometric detection was conducted using multiple-reaction monitoring via an electrospray ionization source in negative ionization mode. Samples were pre-treated by a single-step protein precipitation with acetonitrile, and bergenin was used as internal standard. After oral administration of 3 mL/kg E. ulmoides extract in rats, the maximum plasma concentrations of pinoresinol glucoside and chlorogenic acid were 57.44 and 61.04 ng/mL, respectively. The times to reach the maximum plasma concentration were 40.00 and 23.33 min for pinoresinol glucoside and chlorogenic acid, respectively. The intra- and inter-day precision (RSD) values for the two analytes were <2.46 and 5.15%, respectively, and the accuracy (RE) values ranged from -12.76 to 0.00. This is the first study on pharmacokinetics of bioactive compounds in rat plasma after oral administration of E. ulmoides extract. Copyright © 2017 John Wiley & Sons, Ltd.

PCI-GC-MS-MS approach for identification of non-amino organic acid and amino acid profiles.

PubMed

Luan, Hemi; Yang, Lin; Ji, Fenfen; Cai, Zongwei

2017-03-15

Alkyl chloroformate have been wildly used for the fast derivatization of metabolites with amino and/or carboxyl groups, coupling of powerful separation and detection systems, such as GC-MS, which allows the comprehensive analysis of non-amino organic acids and amino acids. The reagents involving n-alkyl chloroformate and n-alcohol are generally employed for providing symmetric labeling terminal alkyl chain with the same length. Here, we developed an asymmetric labeling strategy and positive chemical ionization gas chromatography-tandem mass spectrometry (PCI-GC-MS-MS) approach for determination of non-amino organic acids and amino acids, as well as the short chain fatty acids. Carboxylic and amino groups could be selectively labelled by propyl and ethyl groups, respectively. The specific neutral loss of C 3 H 8 O (60Da), C 3 H 5 O 2 (74Da) and C 4 H 8 O 2 (88Da) were useful in the selective identification for qualitative analysis of organic acids and amino acid derivatives. PCI-GC-MS-MS using multiple reaction monitoring (MRM) was applied for semi-quantification of typical non-amino organic acids and amino acids. This method exhibited a wide range of linear range, good regression coefficient (R 2 ) and repeatability. The relative standard deviation (RSD) of targeted metabolites showed excellent intra- and inter-day precision (<5%). Our method provided a qualitative and semi-quantitative PCI-GC-MS-MS, coupled with alkyl chloroformate derivatization. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous Analysis of Iridoid Glycosides and Anthraquinones in Morinda officinalis Using UPLC-QqQ-MS/MS and UPLC-Q/TOF-MSE.

PubMed

Zhao, Xiangsheng; Wei, Jianhe; Yang, Meihua

2018-05-03

Morinda officinalis is an important herbal medicine and functional food, and its main constituents include anthraquinone and iridoid glycosides. Quantification of the main compounds is a necessary step to understand the quality and therapeutic properties of M. officinalis , but this has not yet been performed based on liquid chromatography/tandem mass spectrometry (LC-MS/MS). Analytes were extracted from M. officinalis by reflux method. Ultrahigh-performance liquid chromatography coupled with a triple quadrupole mass spectrometry (UPLC-QqQ-MS) using multiple reaction monitoring (MRM) mode was applied for quantification. Fragmentation pathways of deacetyl asperulosidic acid and rubiadin were investigated based on UPLC with quadrupole time-of-flight tandem mass spectrometry (Q/TOF-MS) in the MS E centroid mode. The method showed a good linearity over a wide concentration range (R² ≥ 0.9930). The limits of quantification of six compounds ranged from 2.6 to 27.57 ng/mL. The intra- and inter-day precisions of the investigated components exhibited an RSD within 4.5% with mean recovery rates of 95.32⁻99.86%. Contents of selected compounds in M. officinalis varied significantly depending on region. The fragmentation pathway of deacetyl asperulosidic and rubiadin was proposed. A selective and sensitive method was developed for determining six target compounds in M. officinalis by UPLC-MS/MS. Furthermore, the proposed method will be helpful for quality control and identification main compounds of M. officinalis .

Natural deep eutectic solvents as eco-friendly and sustainable dilution medium for the determination of residual organic solvents in pharmaceuticals with static headspace-gas chromatography.

PubMed

Wang, Meilian; Fang, Sheng; Liang, Xianrui

2018-06-04

Reported here is a simple and rapid static headspace gas chromatography (SHS-GC) method for the determination of trace solvents including ethanol, isopropanol, n-butanol, 1,4-dioxane, tetrahydrofuran, acetonitrile, methanol and acetone which commonly used in drug production process. Natural deep eutectic solvents (NADESs) are firstly used as the matrix medium for this method, which provided high sensitivity for residual solvents detection. With the optimized method, validation experiments were performed and the data showed excellent linearity for all the solvents (R 2 ≥ 0.999, n = 7). The limits of detection (LOD) for ethanol, isopropanol, n-butanol, 1,4-dioxane, tetrahydrofuran, acetonitrile, methanol and acetone are 0.09, 0.08, 0.07, 0.11, 0.06, 0.10, 0.12 and 0.08 μg g -1 , respectively. Accuracy was checked by a recovery experiment at three different levels, and the recoveries of the tested solvents were ranged from 94.3% to 105.4%. The relative standard deviation (RSD) of each solvent for intra- and inter-day precision is in the range of 0.85 to 3.65 and 1.51 to 4.53, respectively. The developed approach can be readily used for determination of the residual solvents in six active pharmaceutical ingredients including pramipexole dihydrochloride, rivaroxaban, lisinopril, ramipril, imatinib mesylate and sitagliptin. Copyright © 2018 Elsevier B.V. All rights reserved.

Hollow Fiber Supported Liquid Membrane Extraction Combined with HPLC-UV for Simultaneous Preconcentration and Determination of Urinary Hippuric Acid and Mandelic Acid

PubMed Central

Bahrami, Abdulrahman; Ghamari, Farhad; Yamini, Yadollah; Ghorbani Shahna, Farshid; Moghimbeigi, Abbas

2017-01-01

This work describes a new extraction method with hollow-fiber liquid-phase microextraction based on facilitated pH gradient transport for analyzing hippuric acid and mandelic acid in aqueous samples. The factors affecting the metabolites extraction were optimized as follows: the volume of sample solution was 10 mL with pH 2 containing 0.5 mol·L−1 sodium chloride, liquid membrane containing 1-octanol with 20% (w/v) tributyl phosphate as the carrier, the time of extraction was 150 min, and stirring rate was 500 rpm. The organic phase immobilized in the pores of a hollow fiber was back-extracted into 24 µL of a solution containing sodium carbonate with pH 11, which was placed inside the lumen of the fiber. Under optimized conditions, the high enrichment factors of 172 and 195 folds, detection limit of 0.007 and 0.009 µg·mL−1 were obtained. The relative standard deviation (RSD) (%) values for intra- and inter-day precisions were calculated at 2.5%–8.2% and 4.1%–10.7%, respectively. The proposed method was successfully applied to the analysis of these metabolites in real urine samples. The results indicated that hollow-fiber liquid-phase microextraction (HF-LPME) based on facilitated pH gradient transport can be used as a sensitive and effective method for the determination of mandelic acid and hippuric acid in urine specimens. PMID:28208685

Simultaneous determination of tetrahydropalmatine, protopine, and palmatine in rat plasma by LC-ESI-MS and its application to a pharmacokinetic study.

PubMed

Ma, Hongda; Wang, Yongjun; Guo, Tao; He, Zhonggui; Chang, Xinyu; Pu, Xiaohui

2009-02-20

A sensitive and specific liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method has been developed and validated for the simultaneous quantification of tetrahydropalmatine, protopine and palmatine in rat plasma using phenacetin as the internal standard (IS). Two hundred microliters plasma samples were extracted by dichloromethane under a strong basic condition. The analytes were separated by a C18 column and detected with a single quadrupole mass spectrometer. The used mobile phase was acetonitrile-water (40:60, v/v) containing 5mM ammonium acetate and 0.2% glacial acetic acid. Detection was carried out by positive electrospray ionization in selected ion reaction (SIR) mode at m/z 356.6 for tetrahydropalmatine, 354.6 for protopine, 352.6 for palmatine and 180.4 for the IS, respectively. The method was validated over the concentration range of 1.00-500ngmL(-1) and the lower limit of quantification (LLOQ) was 1.00ngmL(-1) for all three analytes. The intra- and inter-day precision values were less than 9% relative standard deviation (R.S.D.), and the relative error ranged from -7.4 to 4.8%. The extraction recoveries were on average 91.42% for tetrahydropalmatine, 84.75% for protopine, 57.26% for palmatine, and 83.18% for IS. The validated method was successfully applied to a pharmacokinetic study of tetrahydropalmatine, protopine and palmatine in rats after oral administration of Rhizoma Corydalis Decumbentis extract.

Simultaneous determination of limonin, dictamnine, obacunone and fraxinellone in rat plasma by a validated UHPLC-MS/MS and its application to a pharmacokinetic study after oral administration of Cortex Dictamni extract.

PubMed

Wang, Pei; Sun, Jianbo; Gao, Enze; Zhao, Yunli; Qu, Wei; Yu, Zhiguo

2013-06-01

A rapid and selective ultra high performance liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of four major ingredients in Cortex Dictamni extract, including limonin, dictamnine, obacunone and fraxinellone in rats plasma. Nimodipine was used as the internal standard. Following extraction by methyl tert-butyl ether, the analytes were separated on a Thermo Syncronis C18 column by a gradient elution within a runtime of 9min. The mobile phase consisted of A (methanol) and B (2mmol/L ammonium acetate in water). The detection was accomplished by using positive ion electrospray ionization in multiple reaction monitoring mode. The method was linear for all analytes over investigated range with all correlation coefficients greater than 0.998. The lower limits of quantification were 9.18ng/mL for limonin, 12.0ng/mL for dictamnine, 16.05ng/mL for obacunone and 4.59ng/mL for fraxinellone. The intra- and inter-day precision (RSD%) was within 10% and the accuracy (RE%) ranged from -12.9% to 9.7%. This rapid and sensitive method was fully validated and successfully applied to the pharmacokinetic study of limonin, dictamnine, obacunone and fraxinellone in the rat plasma after oral administration of Cortex Dictamni extract. Copyright © 2013 Elsevier B.V. All rights reserved.

[Comparative data regarding two HPLC methods for determination of isoniazid].

PubMed

Gârbuleţ, Daniela; Spac, A F; Dorneanu, V

2009-01-01

For the determination of isoniazide (isonicotinic acid hydrazide - HIN) two different HPLC methods were developed and validated. Both experiments were performed using a Waters 2695 liquid chromatograph and a UV - Waters 2489 detector. The first method (I) used a Nucleosil 100-10 C18 column (250 x 4.6 mm), a mobile phase formed by a mixture of acetonitrile/10(-2) M oxalic acid (80/20) and a flow of 1.5 mL/ min; detection was done at 230 nm. The second method (II) used a Luna 100-5 C18 column (250 x 4.6 mm), a mobile phase formed by a mixture of methanol/acetate buffer, pH = 5.0 (20/ 80), a flow of 1 mL/min; detection was done at 270 nm. Both methods were validated, the correlation coefficients were 0.9998 (I) and 0.9999 (II), the detection limits were 0.6 microg/mL (I) and 0.055 microg/mL (II), the quantitation limits were 1.9 microg/mL (I) and 0.2 microg/ mL (II). There were also studied: the system precision (RSD = 0.1692% (I) and 0.2000% (II)), the method precision (RSD = 1.1844% (I) and 0.6170% (II)) and the intermediate precision (RSD = 1.8058% (I) and 0.5970% (II)). The accuracy was good, the calculated recoveries were 102.66% (I) and 101.36 (II). Both validated methods were applied for HIN determination from tablets with good and comparable results.

Magnetic mesoporous molecularly imprinted polymers based on surface precipitation polymerization for selective enrichment of triclosan and triclocarban.

PubMed

Wang, Xuemei; Huang, Pengfei; Ma, Xiaomin; Du, Xinzhen; Lu, Xiaoquan

2018-02-16

Novel magnetic mesoporous molecularly imprinted polymers (MMIPs) were prepared based on surface precipitation polymerization using Triclosan (TCS) as template and methacrylic acid as functional monomer. The synthesized MMIPs-TCS were applied to the adsorbent of magnetic solid-phase extraction (MSPE) coupled with HPLC for the enrichment and determination of TCS. The MMIPs-TCS were characterized by fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2 adsorption-desorption transmission, and vibrating sample magnetometry. Under the optimum condition, the MMIPs-TCS-MSPE-HPLC method shows low limits of detection (LODs) (0.20-0.90 μg L -1 ) and limits of quantification detection (LOQs) (0.66-2.97 μg L -1 ), wide linear ranges from 10.0 to 1000 μg L -1 for each compound with exception of 2,4,6-TCP from 20.0 to 1000 μg L -1 , and acceptable reproducibility (relative standard deviation, RSD <6.6% for intra-day, RSD <8.1% for inter-day). The satisfactory recoveries were in the range of 89.5%-108.4% with good RSDs less than 8.0% at the three spiked levels of 20, 50 and 80 μg L -1 . Moreover, the adsorption experiments show the MMIPs-TCS possess rapid binding affinity, excellent magnetic response, specific selectivity and high adsorption capacity toward TCS with a maximum adsorption capacity of 1955.8 μg g -1 . Copyright © 2018 Elsevier B.V. All rights reserved.

Iptycene-based stationary phase with three-dimensional aromatic structure for highly selective separation of H-bonding analytes and aromatic isomers.

PubMed

Yang, Xiaohong; Han, Ying; Qi, Meiling; Chen, Chuanfeng

2016-05-06

Unique structures and molecular recognition ability endow iptycene derivatives with great potential as stationary phases in chromatography, which, however, has not been explored yet. Herein, we report the first example of utilizing a pentiptycene quinone (PQ) for gas chromatographic (GC) separations. Remarkably, the statically coated capillary column with the stationary phase achieved extremely high column efficiency of 4800 plates/m. It exhibited preferential retention and high resolving capability for H-bonding and aromatic analytes and positional isomers, showing advantages over the ordinary polysiloxane phase. Moreover, the fabricated iptycene column showed excellent separation repeatability with RSD values of 0.02-0.06% for intra-day, 0.20-0.35% for inter-day and 3.1-5.5% for between-column, respectively. In conclusion, iptycene derivatives as a new class of stationary phases show promising future for their use in GC separations. Copyright © 2016 Elsevier B.V. All rights reserved.

Video image analysis in the Australian meat industry - precision and accuracy of predicting lean meat yield in lamb carcasses.

PubMed

Hopkins, D L; Safari, E; Thompson, J M; Smith, C R

2004-06-01

A wide selection of lamb types of mixed sex (ewes and wethers) were slaughtered at a commercial abattoir and during this process images of 360 carcasses were obtained online using the VIAScan® system developed by Meat and Livestock Australia. Soft tissue depth at the GR site (thickness of tissue over the 12th rib 110 mm from the midline) was measured by an abattoir employee using the AUS-MEAT sheep probe (PGR). Another measure of this thickness was taken in the chiller using a GR knife (NGR). Each carcass was subsequently broken down to a range of trimmed boneless retail cuts and the lean meat yield determined. The current industry model for predicting meat yield uses hot carcass weight (HCW) and tissue depth at the GR site. A low level of accuracy and precision was found when HCW and PGR were used to predict lean meat yield (R(2)=0.19, r.s.d.=2.80%), which could be improved markedly when PGR was replaced by NGR (R(2)=0.41, r.s.d.=2.39%). If the GR measures were replaced by 8 VIAScan® measures then greater prediction accuracy could be achieved (R(2)=0.52, r.s.d.=2.17%). A similar result was achieved when the model was based on principal components (PCs) computed from the 8 VIAScan® measures (R(2)=0.52, r.s.d.=2.17%). The use of PCs also improved the stability of the model compared to a regression model based on HCW and NGR. The transportability of the models was tested by randomly dividing the data set and comparing coefficients and the level of accuracy and precision. Those models based on PCs were superior to those based on regression. It is demonstrated that with the appropriate modeling the VIAScan® system offers a workable method for predicting lean meat yield automatically.

A novel high sensitivity HPLC assay for topiramate, using 4-chloro-7-nitrobenzofurazan as pre-column fluorescence derivatizing agent.

PubMed

Bahrami, Gholamreza; Mohammadi, Bahareh

2007-05-01

A new, sensitive and simple high-performance liquid chromatographic method for analysis of topiramate, an antiepileptic agent, using 4-chloro-7-nitrobenzofurazan as pre-column derivatization agent is described. Following liquid-liquid extraction of topiramate and an internal standard (amlodipine) from human serum, derivatization of the drugs was performed by the labeling agent in the presence of dichloromethane, methanol, acetonitrile and borate buffer (0.05 M; pH 10.6). A mixture of sodium phosphate buffer (0.05 M; pH 2.4): methanol (35:65 v/v) was eluted as mobile phase and chromatographic separation was achieved using a Shimpack CLC-C18 (150 x 4.6 mm) column. In this method the limit of quantification of 0.01 microg/mL was obtained and the procedure was validated over the concentration range of 0.01 to 12.8 microg/mL. No interferences were found from commonly co-administrated antiepileptic drugs including phenytoin, phenobarbital carbamazepine, lamotrigine, zonisamide, primidone, gabapentin, vigabatrin, and ethosuximide. The analysis performance was carried-out in terms of specificity, sensitivity, linearity, precision, accuracy and stability and the method was shown to be accurate, with intra-day and inter-day accuracy from -3.4 to 10% and precise, with intra-day and inter-day precision from 1.1 to 18%.

SPE-UPLC-MS/MS for the determination of phthalate monoesters in rats urine and its application to study the effects of food emulsifier on the bioavailability of priority controlling PAEs.

PubMed

Xu, R; Gao, H T; Zhu, F; Cao, W X; Yan, Y H M; Zhou, X; Xu, Q; Ji, W L

2016-02-15

This research was mainly focused on the effects of food emulsifier on the bioavailability of six priority controlling phthalate acid esters (PAEs) for the further accurate assessment of their toxic effects, using the corresponding phthalate acid monoesters (PAMEs) in rats urine as biomarkers. Glycerin monostearate was chosen as typical food emulsifier. A method was established to determine PAMEs in urine from rats either in experimental group (integrated gavaged with glycerin monostearate and PAEs) or in control group (gavaged with PAEs only), by using solid-phase extraction (SPE) coupled with ultra performance liquid chromatography tandem mass spectrometry (SPE-UPLC-MS/MS). Extraction recoveries were more than 75% for all the PAMEs; the calibration curve was linear in the range of 1.0-1000.0ng/mL with R(2)>0.995; the limits of detection (LOD) were 0.30ng/mL-0.50ng/mL. In addition, by analysing quality control (QC) urine samples in 3 days, it showed that the method was precise and accurate, for the intra-day and inter-day RSD within 16%, and the accuracy more than 82%. Internal exposure amount of all PAEs in experimental group was significantly higher than that in control group with p values of less than 0.05 except for butyl benzyl phthalates (BBP) (P=0.07). The bioavailability of all PAEs ranged from 5.03% to 109.35% with the presence of food emulsifiers glycerin monostearate, observably higher than that without glycerin monostearate (1.12% to 54.39%). It indicated that food emulsifiers increased the bioavailability of PAEs and may lead to potential food safety risk, which should bring awareness and be further studied. Copyright © 2016 Elsevier B.V. All rights reserved.

Development and validation of rapid and simultaneous method for determination of 12 hair-growth compounds in adulterated products by UHPLC-MS/MS.

PubMed

Park, Han Na; Lee, Ji Hyun; Park, Sung-Kwan; Baek, Sun Young; Lee, Yong-Moon; Kang, Hoil

2018-03-01

Synthetic hair-growth compounds have been illegally used in diverse products to enhance the short-term efficacy of these products. In this study, a rapid and simultaneous method for the determination of hair-growth compounds in adulterated products based on ultra high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. The limit of detection (LOD) and limit of quantitation (LOQs) of the method were 0.08-43.6ng/mL and 0.27-145ng/mL for the solid-, liquid-, and cream-type samples, respectively. Good calibration linearity for all compounds was demonstrated with a correlation coefficient (r 2 ) higher than 0.997. The intra- and inter-assay precisions were within 11%. The corresponding accuracies were 86-117% and 81-113%, respectively. The mean recoveries obtained for the solid-, liquid, and cream-type samples ranged from 87 to 114%, with a relative standard deviation (RSD) within 6%. The RSD of the stability evaluated at 4°C for 48h was less than 6%. The established method was used to screen 76 samples advertised as hair-growth treatments, from online and offline markets, over the course of two years. In 10% of the samples, four compounds, including triaminodil, minoxidil, finasteride, methyltestosterone, and testosterone-propionate were detected. The concentrations were in the range of 0.5-16.4mg/g. This technique provides a reliable platform for technical analysis for continuous monitoring of adulterated products to protect public health. Copyright © 2018 Elsevier B.V. All rights reserved.

Changes of serum neurohormone after renal sympathetic denervation in dogs with pacing-induced heart failure.

PubMed

Zhao, Qingyan; Huang, He; Wang, Xule; Wang, Xiaozhan; Dai, Zixuan; Wan, Peixing; Guo, Zongwen; Yu, Shengbo; Tang, Yanhong; Huang, Congxin

2014-01-01

Neurohormonal activation is a commonly cited array of phenomena in the body's physiologic response to heart failure (HF). The aim of the present study was to determine the change law of serum neurohormones after renal sympathetic denervation (RSD) in dogs with pacing-induced HF. Twenty-eight beagles were randomly divided into control group, RSD group, HF group and HF + RSD group. The control group was implanted pacemakers without pacing; the RSD group underwent renal artery ablation without pacing; the HF group was implanted pacemakers with ventricular pacing at 240 bpm for 3 weeks; and HF + RSD group underwent renal artery ablation and with ventricular pacing at 240 bpm for 3 weeks. Blood samples were taken at baseline, and 3, 6, 9, 12, 15, 18, 21 days in all the dogs for neurohormones measurement. After 3 weeks, the systolic femoral artery pressures in the HF and HF + RSD groups were reduced after pacing 3 weeks. There was an increase significantly in BNP, angiotensin II, aldosterone, endothelin-1 and decrease in renalase after 3 weeks when compared with baseline in HF group. RSD significantly suppressed the changes of plasma neurohormones concentration in experimental HF, but RSD had not obviously impact on the levels of plasma neurohormones during 3 weeks in RSD group. RSD attenuates the changes of levels of plasma neurohormones in the activated renin-angiotensin-aldosterone system (RAAS) but had not obviously effect in the normal physiology of RAAS.

Spectrophotometric determination of flucloxacillin and dicloxacillin in pure and dosage forms.

PubMed

El-Dien, F A Nour; Mohamed, Gehad G; Farag, Eman Y Z A

2006-05-01

A simple, rapid and accurate spectrophotometric method for the determination of antibiotic drugs, flucloxacillin (Fluclox) and dicloxacillin (Diclox), in pure form and different pharmaceutical preparations has been developed. The charge transfer (CT) reactions between Fluclox and Diclox as electron donors and 7,7,8,8-tetracyanoquinodimethane (TCNQ) and tetracyanoethylene (TCNE) as pi-acceptors to give highly coloured complex species have been spectrophotometrically studied. The optimum experimental conditions for these CT reactions have been studied carefully. Beer's law is obeyed over the concentration ranges of 4-180 microg mL(-1) and 4-70 microg mL(-1) for Fluclox and Diclox drugs using TCNQ and TCNE reagents, respectively. The Sandell sensitivities (S) are found to be 0.016-0.035 microg cm(-2) and 0.011-0.016 microg cm(-2) for Fluclox and Diclox, respectively, which indicate the high sensitivity of the proposed method. The relative standard deviations (R.S.D.: 0.08-0.49 and 0.15-0.80) for the determination of Fluclox and (R.S.D.: 0.05-0.75 and 0.13-0.75) for Diclox were obtained for four to six replicates using TCNQ and TCNE reagents, respectively, refer to the high accuracy and precision of the proposed method. These results are also confirmed by the between-day precision and the percent recovery of 99.90-100.1 and 99.60-100.4 for Fluclox and 99.90-100.5 and 99.40-100.1 for Diclox using TNCQ and TCNE reagents, respectively. The results obtained for the two reagents are comparable with those obtained by the official method.

Residue analysis of fipronil and difenoconazole in okra by liquid chromatography tandem mass spectrometry and their food safety evaluation.

PubMed

Hingmire, Sandip; Oulkar, Dasharath P; Utture, Sagar C; Ahammed Shabeer, T P; Banerjee, Kaushik

2015-06-01

A liquid chromatography tandem mass spectrometry (LC-MS/MS) based method is reported for simultaneous analysis of fipronil (plus its metabolites) and difenoconazole residues in okra. The sample preparation method involving extraction with ethyl acetate provided 80-107% recoveries for both the pesticides with precision RSD within 4-17% estimated at the limits of quantification (LOQ, fipronil=1ngg(-1), difenoconazole=5ngg(-1)) and higher fortification levels. In field, both the pesticides dissipated with half-life of 2.5days. The estimated pre-harvest intervals (PHI) for fipronil and difenoconazole were 15 and 19.5days, and 4 and 6.5days at single and double dose of field applications, respectively. Decontamination of incurred residues by washing and different cooking treatments was quite efficient in minimizing the residue load of both the chemicals. Okra samples harvested after the estimated PHIs were found safe for human consumption. Copyright © 2014 Elsevier Ltd. All rights reserved.

Determination of crenolanib in human serum and cerebrospinal fluid by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS).

PubMed

Roberts, Michael S; Turner, David C; Owens, Thandranese S; Ramachandran, Abhijit; Wetmore, Cynthia; Throm, Stacy L; Stewart, Clinton F

2013-06-15

A LC-ESI-MS/MS method for the determination of crenolanib (CP-868,596) in human serum was developed and validated employing d4-CP-868,596 as an internal standard (ISTD). In addition to human serum, the method was also partially validated for crenolanib determination in human cerebrospinal fluid (CSF) samples. Sample aliquots (50μl of serum or CSF) were prepared for analysis using liquid-liquid extraction (LLE) with tert-butyl methyl ether. Chromatography was performed using a phenomenex Gemini C18 column (3μm, 100mm×4.6mm I.D.) in a column heater set at 50°C and an isocratic mobile phase (methanol/water/formic acid at a volume ratio of 25/25/0.15, v/v/v). The flow rate was 0.45mL/min, and the retention time for both analyte and ISTD was less than 3.5min. Samples were analyzed with an API-5500 LC-MS/MS system (ESI) in positive ionization mode coupled to a Shimadzu HPLC system. The ion transitions monitored were m/z 444.4→373.1 and m/z 448.2→374.2 for crenolanib and ISTD, respectively. The method was linear over the range of 5-1000ng/mL for serum and 0.5-1000ng/mL for CSF. For human serum, both intra-day and inter-day precision were <4%, while intra-day and inter-day accuracy were within 8% of nominal values. Recovery was greater than 50% for both the analyte and ISTD. For CSF samples, both intra-day and inter-day precision were <9% except at the lower limit of quantification (LLOQ) which was <17%. The intra-day and inter-day accuracy were within 11% of the nominal CSF concentrations. After validation, this method was successfully applied to the analysis of serial pharmacokinetic samples obtained from a child treated with oral crenolanib. Copyright © 2013 Elsevier B.V. All rights reserved.

A Study of Method Development, Validation, and Forced Degradation for Simultaneous Quantification of Paracetamol and Ibuprofen in Pharmaceutical Dosage Form by RP-HPLC Method

PubMed Central

Jahan, Md. Sarowar; Islam, Md. Jahirul; Begum, Rehana; Kayesh, Ruhul; Rahman, Asma

2014-01-01

A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP) guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH). For this, an isocratic condition of mobile phase comprising phosphate buffer (pH 6.8) and acetonitrile in a ratio of 65:35, v/v at a flow rate of 0.7 mL/minute over RP C18 (octadecylsilane (ODS), 150 × 4.6 mm, 5 μm, Phenomenex Inc.) column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (R2) values of 0.999 and 1.0 for paracetamol and ibuprofen respectively, which were within the limit of correlation coefficient (R2 > 0.995). The percent recoveries for two drugs were found within the acceptance limit of (97.0–103.0%). Intra-and inter-day precision studies of the new method were less than the maximum allowable limit percentage of relative standard deviation (%RSD) ≤ 2.0. Forced degradation of the drug product was carried out as per the ICH guidelines with a view to establishing the stability-indicating property of this method and providing useful information about the degradation pathways, degradation products, and how the quality of a drug substance and drug product changes with time under the influence of various stressing conditions. The degradation of ibuprofen was within the limit (5–20%, according to the guideline of ICH), while paracetamol showed <20% degradation in oxidation and basic condition. PMID:25452691

A Study of Method Development, Validation, and Forced Degradation for Simultaneous Quantification of Paracetamol and Ibuprofen in Pharmaceutical Dosage Form by RP-HPLC Method.

PubMed

Jahan, Md Sarowar; Islam, Md Jahirul; Begum, Rehana; Kayesh, Ruhul; Rahman, Asma

2014-01-01

A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP) guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH). For this, an isocratic condition of mobile phase comprising phosphate buffer (pH 6.8) and acetonitrile in a ratio of 65:35, v/v at a flow rate of 0.7 mL/minute over RP C18 (octadecylsilane (ODS), 150 × 4.6 mm, 5 μm, Phenomenex Inc.) column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (R (2)) values of 0.999 and 1.0 for paracetamol and ibuprofen respectively, which were within the limit of correlation coefficient (R (2) > 0.995). The percent recoveries for two drugs were found within the acceptance limit of (97.0-103.0%). Intra-and inter-day precision studies of the new method were less than the maximum allowable limit percentage of relative standard deviation (%RSD) ≤ 2.0. Forced degradation of the drug product was carried out as per the ICH guidelines with a view to establishing the stability-indicating property of this method and providing useful information about the degradation pathways, degradation products, and how the quality of a drug substance and drug product changes with time under the influence of various stressing conditions. The degradation of ibuprofen was within the limit (5-20%, according to the guideline of ICH), while paracetamol showed <20% degradation in oxidation and basic condition.

Determination of five flavonoids in different parts of Fordia cauliflora by ultra performance liquid chromatography/triple-quadrupole mass spectrometry and chemical comparison with the root of Millettia pulchra var. laxior

PubMed Central

2013-01-01

Background The root of Fordia cauliflora Hemsl (FC) has long been used in southern China for the treatment of rheumatism, bruises, dementia in children, and valetudinarianism. However, sometimes it is mixed with other parts. And it has always been confused with the root of Millettia pulchra (Benth.) Kurz var. laxior (Dunn) Z. Wei (MP) by the local people. The chemical differences between the two ethnic drugs are not clear until now. The aim of this study is to develop a precise and accurate method to characterize and quantify multiple chemical components of FC, which is helpful for the quality evaluation and identification of FC. Results A method coupling ultra performance liquid chromatography (UPLC) with triple-quadrupole mass spectrometry (QqQ-MS) was first developed for simultaneous determination of five flavonoids in different parts of FC and the root of MP, based on a UPLC-diode array detection (DAD) fingerprint method. All calibration curves showed good linearity (R2>0.99) within test ranges. The overall LOD and LOQ were lower than 2.5 ng/mL and 5.0 ng/mL, respectively. The RSDs for intra- and inter-day of five analytes were less than 2.83% and 3.04%, respectively. Recovery studies for the quantified compounds were found to be within the range 93.6-99.8% with RSD less than 5.73%. The results suggest that the root, traditionally used medicinal part, yields the highest flavanoid content in FC. Pachycarin A, 3′,4′-dimethoxy(2′′,3′′:7,8) furanoflavone, karanjachromene and isoderricin A can be used to differentiate between FC and MP samples. Conclusions The present method is specific, precise and reliable, and is suitable for characterizing and quantifying multiple chemical components of FC. PMID:23870070

Simultaneous determination of quercetin, kaempferol and isorhamnetin accumulated human breast cancer cells, by high-performance liquid chromatography.

PubMed

Wang, Yi; Cao, Jiang; Weng, Jian-Hua; Zeng, Su

2005-09-01

Quercetin, kaempferol and isorhamnetin are the most important constituents in ginkgo flavonoids. A simple, rapid and sensitive high-performance liquid chromatography method was developed to simultaneously determine quercetin, kaempferol and isorhamnetin absorped by human breast cancer cells. Cells were treated with ginkgo flavonols and then lysed with Triton-X 100. The flavonols in the samples were measured by RP-HPLC with a C18 column after a simple extraction with a mixture of ether and acetone. The mobile phase contained phosphate buffer (pH 2.0; 10 mM) tetrahydrofuran, methanol and isopropanol (65:15:10:20, v/v/v/v). The ultraviolet detector was operated at 380 nm. The calibration curve was linear from 0.1 to 1.0 microM (r > 0.999) for each flavonol. The mean extraction efficiency was about 70%. The recovery of the assay was between 98.9 and 100.6%. The limit of detection was 0.01 microM for quercetin and kaempferol and 0.05 microM for isorhamnetin. The limit of quantitation was 0.1 microM (R.S.D.<10%) for each flavonol. The intra- and inter-day coefficients of variation were less than 10% (R.S.D.). The validated method was applied to quantify quercetin, kaempferol and isorhamnetin in human breast cancer Bcap37 and Bcap37/MDR1 cells.

Use of experimental design for optimisation of the cold plasma ICP-MS determination of lithium, aluminum and iron in soft drinks and alcoholic beverages.

PubMed

Bianchi, F; Careri, M; Maffini, M; Mangia, A; Mucchino, C

2003-01-01

A sensitive method for the simultaneous determination of (7)Li, (27)Al and (56)Fe by cold plasma ICP-MS was developed and validated. Experimental design was used to investigate the effects of torch position, torch power, lens 2 voltage, and coolant flow. Regression models and desirability functions were applied to find the experimental conditions providing the highest global sensitivity in a multi-elemental analysis. Validation was performed in terms of limits of detection (LOD), limits of quantitation (LOQ), linearity and precision. LODs were 1.4 and 159 ng L(-1) for (7)Li and (56)Fe, respectively; the highest LOD found being that for (27)Al (425 ng L(-1)). Linear ranges of 5 orders of magnitude for Li and 3 orders for Fe were statistically verified for each compound. Precision was evaluated by testing two concentration levels, and good results in terms of both intra-day repeatability and intermediate precision were obtained. RSD values lower than 4.8% at the lowest concentration level were calculated for intra-day repeatability. Commercially available soft drinks and alcoholic beverages contained in different packaging materials (TetraPack, polyethylene terephthalate (PET), commercial cans and glass) were analysed, and all the analytes were detected and quantitated. Copyright 2002 John Wiley & Sons, Ltd.

Simultaneous quantification of nicotine, opioids, cocaine, and metabolites in human fetal postmortem brain by liquid chromatography tandem mass spectrometry

PubMed Central

Shakleya, Diaa M.

2011-01-01

A validated method for simultaneous LCMSMS quantification of nicotine, cocaine, 6-acetylmorphine (6AM), codeine, and metabolites in 100 mg fetal human brain was developed and validated. After homogenization and solid-phase extraction, analytes were resolved on a Hydro-RP analytical column with gradient elution. Empirically determined linearity was from 5–5,000 pg/mg for cocaine and benzoylecgonine (BE), 25–5,000 pg/mg for cotinine, ecgonine methyl ester (EME) and 6AM, 50–5000 pg/mg for trans-3-hydroxycotinine (OH-cotinine) and codeine, and 250–5,000 pg/mg for nicotine. Potential endogenous and exogenous interferences were resolved. Intra- and inter-assay analytical recoveries were ≥92%, intra- and inter-day and total assay imprecision were ≤14% RSD and extraction efficiencies were ≥67.2% with ≤83% matrix effect. Method applicability was demonstrated with a postmortem fetal brain containing 40 pg/mg cotinine, 65 pg/mg OH-cotinine, 13 pg/mg cocaine, 34 pg/mg EME, and 525 pg/mg BE. This validated method is useful for determination of nicotine, opioid, and cocaine biomarkers in brain. PMID:19229524

A novel pyrogallol red-based assay to assess catalase activity: Optimization by response surface methodology.

PubMed

Abderrahim, Mohamed; Arribas, Silvia M; Condezo-Hoyos, Luis

2017-05-01

Pyrogallol red (PGR) was identified as a novel optical probe for the detection of hydrogen peroxide (H 2 O 2 ) based on horseradish peroxidase (HRP)-catalyzed oxidation. Response surface methodology (RSM) was applied as a tool to optimize the concentrations of PGR (100µmolL -1 ), HRP (1UmL -1 ) and H 2 O 2 (250µmolL -1 ) and used to develop a sensitive PGR-based catalase (CAT) activity assay (PGR-CAT assay). N-ethylmaleimide -NEM- (102mmolL -1 ) was used to avoid interference produced by thiol groups while protecting CAT activity. Incubation time (30min) for samples or CAT used as standard and H 2 O 2 as well as signal stability (stable between 5 and 60min) were also evaluated. PGR-CAT assay was linear within the range of 0-4UmL -1 (R 2 =0.993) and very sensitive with limits of detection (LOD) of 0.005UmL -1 and quantitation (LOQ) of 0.01UmL -1 . PGR-CAT assay showed an adequate intra-day RSD=0.6-9.5% and inter-day RSD=2.4-8.9%. Bland-Altman analysis and Passing-Bablok and Pearson correlation analysis showed good agreement between CAT activity as measured by the PRG-CAT assay and the Amplex Red assay. The PGR-CAT assay is more sensitive than all the other colorimetric assays reported, particularly the Amplex Red assay, and the cost of PGR is a small fraction (about 1/1000) of that of an Amplex Red probe, so it can be expected to find wide use among scientists studying CAT activity in biological samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination of icariin, naringin and osthole in rat plasma by UPLC-MS/MS and its application for pharmacokinetic study after oral administration of Gushudan capsules.

PubMed

Lu, Yuejuan; Li, Ning; Deng, Ying; Zhao, Longshan; Guo, Xingjie; Li, Famei; Xiong, Zhili

2015-07-01

A rapid, sensitive and selective ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the simultaneous determination of icariin, naringin and osthole in rat plasma. Plasma samples pretreatment involved a one-step liquid-liquid extraction with a mixture of ethyl acetate-methyl tert-butyl ether (3:1, ν/ν). The separation was performed on an ACQUITY UPLC™ BEH C18 column with a gradient mobile phase system of methanol and water. The detection was performed on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization (ESI) by multiple reactions monitoring (MRM), with the transitions at m/z 513.3→366.8 (icariin), m/z 579.3→150.9 (naringin), m/z 245.1→189.0 (osthole) and m/z 237.1→194.1 (IS), respectively. A good linear response was observed over the concentration ranges of 1.06-424ng/ml, 2.10-525ng/ml and 1.05-1.05×10(3)ng/ml with lower limit of quantification (LLOQ) of 1.06, 2.10 and 1.05ng/ml for icariin, naringin and osthole, respectively. The intra- and inter-day precisions (R.S.D.) were within 14.3%, and the accuracy (R.E.) ranged from -4.1% to 4.6% at three quality control levels. The sensitive and selective method was applied to a pharmacokinetic study of icarrin, naringin and osthole in rats after oral administration of Gushudan capsule. Copyright © 2015 Elsevier B.V. All rights reserved.

Chemical profiling and quantification of Chinese medicinal formula Huang-Lian-Jie-Du decoction, a systematic quality control strategy using ultra high performance liquid chromatography combined with hybrid quadrupole-orbitrap and triple quadrupole mass spectrometers.

PubMed

Yang, Yang; Wang, Hong-Jie; Yang, Jian; Brantner, Adelheid H; Lower-Nedza, Agnieszka D; Si, Nan; Song, Jian-Fang; Bai, Bing; Zhao, Hai-Yu; Bian, Bao-Lin

2013-12-20

To clarify and quantify the chemical profiling of Huang-Lian-Jie-Du decoction (HLJDD) rapidly, a feasible and accurate strategy was developed by applying high speed LC combined with hybrid quadrupole-orbitrap mass spectrometer (Q-Exactive) and UHPLC-triple quadruple mass spectrometer (UHPLC-QqQ MS). 69 compounds, including iridoids, alkaloids, flavonoids, triterpenoid, monoterpene and phenolic acids, were identified by their characteristic high resolution mass data. Among them, 18 major compounds were unambiguously detected by comparing with reference standards. In the subsequent quantitative analysis, 17 representative compounds, selected as quality control markers, were simultaneously detected in 10 batches of HLJDD samples by UHPLC-QqQ MS. These samples were collected from four different countries (regions). Icariin, swertiamarin and corynoline were employed as internal standards for flavonoids, iridoids and alkaloids respectively. All the analytes were detected within 12min. Polarity switching mode was used in the optimization of multiple reaction monitoring (MRM) conditions. Satisfactory linearity was achieved with wide linear range and fine determination coefficient (r(2)>0.9990). The relative standard deviations (RSD) of inter- and intra-day precisions were less than 5.0%. This method was also validated by repeatability, stability (8h) and recovery, with respective RSDs less than 4.6%, 5.0% and 6.3%. This research established a high sensitive and efficient method for the integrating quality control, including identification and quantification of Chinese medicinal formulas. Copyright © 2013 Elsevier B.V. All rights reserved.

Development and validation of a sensitive LC/MS/MS method for the simultaneous determination of naloxone and its metabolites in mouse plasma.

PubMed

Jiang, Hongliang; Wang, Yurong; Shet, Manjunath S; Zhang, Yang; Zenke, Duane; Fast, Douglas M

2011-09-01

A rapid, specific, and reliable LC-MS/MS based bioanalytical method was developed and validated for the simultaneous determination of naloxone (NLX) and its two metabolites, 6β-naloxol (NLL) and naloxone-3β-D-glucuronide (NLG) in mouse plasma. The optimal chromatographic behavior of these analytes was achieved on an Aquasil C18 column (50 mm × 2.1 mm, 5 μm) using reversed phase chromatography. The total LC analysis time per injection was 2.5 min with a flow rate of 1.0 mL/min with gradient elution. Sample preparation via protein precipitation with acetonitrile in a 96-well format was applied for analyses of these analytes. The analytes were monitored by electrospray ionization in positive ion multiple reaction monitoring (MRM) mode. Modification of collision energy besides chromatographic separation was applied to further eliminate interference peaks for NLL and NLG. The method validation was conducted over the curve range of 0.200/0.400/0.500 to 100/200/250 ng/mL for NLX/NLL/NLG, respectively, using 0.0250 mL of plasma sample. The intra- and inter-day precision and accuracy of the quality control samples at low, medium, and high concentration levels showed ≤ 6.5% relative standard deviation (RSD) and -8.3 to -2.5% relative error (RE). The method was successfully applied to determine the concentrations of NLX, NLL, and NLG in incurred mouse plasma samples. Copyright © 2011 Elsevier B.V. All rights reserved.

Capillary electrophoresis tandem mass spectrometry determination of glutamic acid and homocysteine's metabolites: Potential biomarkers of amyotrophic lateral sclerosis.

PubMed

Cieslarova, Zuzana; Lopes, Fernando Silva; do Lago, Claudimir Lucio; França, Marcondes Cavalcante; Colnaghi Simionato, Ana Valéria

2017-08-01

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects both lower and upper motor neurons, leading to muscle atrophy, paralysis, and death caused by respiratory failure or infectious complications. Altered levels of homocysteine, cysteine, methionine, and glutamic acid have been observed in plasma of ALS patients. In this context, a method for determination of these potential biomarkers in plasma by capillary electrophoresis tandem mass spectrometry (CE-MS/MS) is proposed herein. Sample preparation was carefully investigated, since sulfur-containing amino acids may interact with plasma proteins. Owing to the non-thiol sulfur atom in methionine, it was necessary to split sample preparation into two methods: i) determination of homocysteine and cysteine as S-acetyl amino acids; ii) determination of glutamic acid and methionine. All amino acids were separated within 25min by CE-MS/MS using 5molL -1 acetic acid as background electrolyte and 5mmolL -1 acetic acid in 50% methanol/H 2 O (v/v) as sheath liquid. The proposed CE-MS/MS method was validated, presenting RSD values below 6% and 11% for intra- and inter-day precision, respectively, for the middle concentration level within the linear range. The limits of detection ranged from 35 (homocysteine) to 268nmolL -1 (glutamic acid). The validated method was applied to the analysis of plasma samples from a group of healthy individuals and patients with ALS, showing the potential of glutamic acid and homocysteine metabolites as biomarkers of ALS. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous quantification of triterpenoid saponins in rat plasma by UHPLC-MS/MS and its application to a pharmacokinetic study after oral total saponin of Aralia elata leaves.

PubMed

Sun, Yichun; Xue, Juan; Li, Baimei; Lin, Xiaoting; Wang, Zhibin; Jiang, Hai; Zhang, Hongwei; Wang, Qiuhong; Kuang, Haixue

2016-11-01

A rapid, sensitive, and reliable analytical ultra performance liquid chromatography with tandem mass spectrometry method was developed for the simultaneous determination of Aralia-saponin IV, 3-O-β-d-glucopyranosyl-(1→3)-β-d-glucopyranosyl-(1→3)-β-d-glucopyranosyl oleanolic acid 28-O-β-d-glucopyranoside, Aralia-saponin A and Aralia-saponin B after the oral administration of total saponin of Aralia elata leaves in rat plasma. Plasma samples were pretreated by protein precipitation with methanol. The analysis was performed on an ACQUITY UPLC HSS T3 column. The detection was performed on a triple quadrupole tandem mass spectrometer in multiple reaction monitoring mode using an electrospray ionization source with negative ionization mode. Under the experimental conditions, the calibration curves of four analytes had good linearity values (r > 0.991). The intra- and inter-day precision values of the four analytes were ≤ 11.6%, and the accuracy was between -6.2 and 4.2%.The extraction recoveries of four triterpenoid saponins were in the range of 84.06-91.66% (RSD < 10.5%), and all values of the matrix effect were more than 90.30%. The developed analytical method was successfully applied to pharmacokinetic study on simultaneous determination of the four triterpenoid saponins in rat plasma after oral administration of total saponin of Aralia elata leaves, which helps guiding clinical usage of Aralia elata leaves. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of five antiarrhythmic drugs in human plasma by dispersive liquid-liquid microextraction and high-performance liquid chromatography.

PubMed

Jouyban, Abolghasem; Sorouraddin, Mohammad Hossein; Farajzadeh, Mir Ali; Somi, Mohammad Hossein; Fazeli-Bakhtiyari, Rana

2015-03-01

A fast and sensitive high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection was developed and validated for the simultaneous quantitation of five antiarrhythmic drugs (metoprolol, propranolol, carvedilol, diltiazem, and verapamil) in human plasma samples. It involves dispersive liquid-liquid microextraction (DLLME) of the desired drugs from 660 µL plasma and separation using isocratic elution with UV detection at 200 nm. The complete separation of all analytes was achieved within 7 min. Acetonitrile (as disperser solvent) resulting from the protein precipitation procedure was mixed with 100 µL dichloromethane (as an extraction solvent) and rapidly injected into 5 mL aqueous solution (pH 11.5) containing 1% (w/v), NaCl. After centrifugation, the sedimented phase containing enriched analytes was collected and evaporated to dryness. The residue was re-dissolved in 50 µL de-ionized water (acidified to pH 3) and injected into the HPLC system for analysis. Under the optimal conditions, the enrichment factors and extraction recoveries ranged between 4.4-10.8 and 33-82%, respectively. The suggested method was linear (r(2) ≥0.997) over a dynamic range of 0.02-0.80 µg mL(-1) in plasma. The intra- and inter-days relative standard deviation (RSD%) and relative error (RE%) values of the method were below 20%, which shows good precision and accuracy. Finally, this method was applied to the analysis of real plasma samples obtained from the patients treated with these drugs. Copyright © 2014 Elsevier B.V. All rights reserved.

Quantification of maltol in Korean ginseng (Panax ginseng) products by high-performance liquid chromatography-diode array detector

PubMed Central

Jeong, Hyun Cheol; Hong, Hee-Do; Kim, Young-Chan; Rhee, Young Kyoung; Choi, Sang Yoon; Kim, Kyung-Tack; Kim, Sung Soo; Lee, Young-Chul; Cho, Chang-Won

2015-01-01

Background: Maltol, as a type of phenolic compounds, is produced by the browning reaction during the high-temperature treatment of ginseng. Thus, maltol can be used as a marker for the quality control of various ginseng products manufactured by high-temperature treatment including red ginseng. For the quantification of maltol in Korean ginseng products, an effective high-performance liquid chromatography-diode array detector (HPLC-DAD) method was developed. Materials and Methods: The HPLC-DAD method for maltol quantification coupled with a liquid-liquid extraction (LLE) method was developed and validated in terms of linearity, precision, and accuracy. An HPLC separation was performed on a C18 column. Results: The LLE methods and HPLC running conditions for maltol quantification were optimized. The calibration curve of the maltol exhibited good linearity (R2 = 1.00). The limit of detection value of maltol was 0.26 μg/mL, and the limit of quantification value was 0.79 μg/mL. The relative standard deviations (RSDs) of the data of the intra- and inter-day experiments were <1.27% and 0.61%, respectively. The results of the recovery test were 101.35–101.75% with an RSD value of 0.21–1.65%. The developed method was applied successfully to quantify the maltol in three ginseng products manufactured by different methods. Conclusion: The results of validation demonstrated that the proposed HPLC-DAD method was useful for the quantification of maltol in various ginseng products. PMID:26246746

Simultaneous determination of calycosin-7-O-β-D-glucoside, ononin, calycosin, formononetin, astragaloside IV, and astragaloside II in rat plasma after oral administration of Radix Astragali extraction for their pharmacokinetic studies by ultra-pressure liquid chromatography with tandem mass spectrometry.

PubMed

Liu, Xiao-hua; Zhao, Jian-bang; Guo, Long; Yang, Ying-lai; Hu, Fang; Zhu, Rui-juan; Feng, Shi-lan

2014-09-01

A sensitive and reliable ultra-pressure liquid chromatography with tandem mass spectrometry (UPLC-MS) was developed and validated for simultaneous quantification of six main bioactive components, i.e., calycosin-7-O-β-D-glucoside, ononin, calycosin, formononetin, astragaloside IV, and astragaloside II in rat plasma after oral administration of the 95 % ethanol extraction from Radix Astragali. Plasma samples were extracted with Waters Oasis(TM) HLB 1 cc (30 mg) Extraction Cartridges (SPE) separated on an UPLC™ BEH C18 column and detected by MS with electro spray ionization interface in positive selective ion monitoring mode. Calibration curves offered linear ranges of two orders of magnitude with r (2) > 0.99. The method had the lower limit quantification of 1.30, 0.73, 1.17, 2.33, 0.63, and 0.83 ng/mL for ononin, calycosin, calycosin-7-O-β-D-glucoside, formononetin, astragaloside IV, and astragaloside II, respectively, with precision less than 10 %. The RSD of intra- and inter-day variations ranged from 1.66 to 6.46 and 3.39 to 6.58 %. This developed method was applied subsequently to pharmacokinetic studies of the six compounds in rats successfully. The proposed method was for the first time to compare the pharmacokinetic difference between calycosin-7-O-β-D-glucoside and calycosin in rat plasma, so as between ononin and formononetin, and studied to the astragaloside II pharmacokinetics in rat plasma.

Simultaneous quantification of four metabolites of sulfur mustard in urine samples by ultra-high performance liquid chromatography-tandem mass spectrometry after solid phase extraction.

PubMed

Liu, Chang-Cai; Liu, Shi-Lei; Xi, Hai-Ling; Yu, Hui-Lan; Zhou, Shi-Kun; Huang, Gui-Lan; Liang, Long-Hui; Liu, Jing-Quan

2017-04-07

Four HD urinary metabolites including hydrolysis metabolite thiodiglycol (TDG), glutathione-derived metabolite 1,1'-sulfonylbis[2-S-(N-acetylcysteinyl)ethane] (SBSNAE), as well as the β-lyase metabolites 1,1'-sulfonylbis[2-(methylsulfinyl)ethane] (SBMSE) and 1-methylsulfinyl-2-[2-(methylthio) ethylsulfonyl]ethane (MSMTESE) are considered as important biomarkers for short-term retrospective detection of HD exposure. In this study, a single method for simultaneous quantification of the four HD metabolites in urine samples was developed using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The four urinary metabolites were simultaneously extracted from urinary samples using a solid phase extraction (SPE) method with high extraction recoveries for all four metabolites varied in the range of 71.1-103% followed by UHPLC-MS/MS analysis. The SPE is simple and high effective only requiring 0.1mL of urinary samples and 0.5h time consuming. The problem of previous co-elution of TDG and SBSNAE in UHPLC was well solved, and complete separation of TDG, SBSNAE, SBMSE and MSMTESE from SPE-processed urine matrix was obtained to increase specificity and sensitivity. A full method validation was performed for each analyte in urine matrix. The linear range of calibration curves for the four analytes were respectively from 0.50-500ngmL -1 for TDG and SBSNAE, 0.05-500ngmL -1 for SBMSE and MSMTESE with coefficient of determination value (R 2 ) ≥0.990. The limit of detection was 0.25ngmL -1 for TDG and SBSNAE, 0.01ngmL -1 for SBMSE and MSMTESE spiked in normal urine. The intra/inter-day precision for each analyte at three QC levels had relative standard deviation (%RSD) of ≤10.3%, and the intra/inter-day accuracy ranged between 88.0-108%. This developed method allows for simultaneous and trace measurement of four HD urinary metabolites within one single determination with the lowest usage amount of urine samples over all previous methods This study provides a useful tool for early diagnosis and monitoring of HD poisoning for medical treatment with high confidence, avoiding the need for application of several analysis methods. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination of atenolol and amlodipine in tablets by high-performance thin-layer chromatography.

PubMed

Argekar, A P; Powar, S G

2000-01-01

A new simple, precise, rapid and selective high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous determination of atenolol (ATL) and amlodipine (AMLO) in tablets, using methylene chloride:methanol:ammonia solution (25% NH3) (8.8:1.3:0.1; v/v) as the mobile phase and Merck HPTLC plates (0.2 mm thickness) precoated with 60F254 silica gel on aluminium sheet as the stationary phase. Detection was carried out densitometrically using a UV detector at 230 nm. The retention factors of ATL and AMLO were 0.33 and 0.75, respectively. Calibration curves were linear in the range 10-500 microg ml(-1) for both. Assays of ATL and AMLO were 49.87 mg per tablet (relative standard deviation (R.S.D.), 1.3%) and 4.90 mg per tablet (R.S.D., 1.38%) for brand I, and 49.27 mg per tablet (R.S.D., 1.12%) and 4.98 mg per tablet (R.S.D., 1.42%) for brand II, respectively. The percentage recoveries for ATL and AMLO for brands I and II were 99.06 and 99.30%, and 99.27 and 99.15%, respectively.

Whole air canister sampling coupled with preconcentration GC/MS analysis of part-per-trillion levels of trimethylsilanol in semiconductor cleanroom air.

PubMed

Herrington, Jason S

2013-08-20

The costly damage airborne trimethylsilanol (TMS) exacts on optics in the semiconductor industry has resulted in the demand for accurate and reliable methods for measuring TMS at trace levels (i.e., parts per trillion, volume per volume of air [ppt(v)] [~ng/m(3)]). In this study I developed a whole air canister-based approach for field sampling trimethylsilanol in air, as well as a preconcentration gas chromatography/mass spectrometry laboratory method for analysis. The results demonstrate clean canister blanks (0.06 ppt(v) [0.24 ng/m(3)], which is below the detection limit), excellent linearity (a calibration relative response factor relative standard deviation [RSD] of 9.8%) over a wide dynamic mass range (1-100 ppt(v)), recovery/accuracy of 93%, a low selected ion monitoring method detection limit of 0.12 ppt(v) (0.48 ng/m(3)), replicate precision of 6.8% RSD, and stability (84% recovery) out to four days of storage at room temperature. Samples collected at two silicon wafer fabrication facilities ranged from 10.0 to 9120 ppt(v) TMS and appear to be associated with the use of hexamethyldisilazane priming agent. This method will enable semiconductor cleanroom managers to monitor and control for trace levels of trimethylsilanol.

Spectrophotometric method development and validation for determination of chlorpheniramine maleate in bulk and controlled release tablets.

PubMed

Ashfaq, Maria; Sial, Ali Akber; Bushra, Rabia; Rehman, Atta-Ur; Baig, Mirza Tasawur; Huma, Ambreen; Ahmed, Maryam

2018-01-01

Spectrophotometric technique is considered to be the simplest and operator friendly among other available analytical methods for pharmaceutical analysis. The objective of the study was to develop a precise, accurate and rapid UV-spectrophotometric method for the estimation of chlorpheniramine maleate (CPM) in pure and solid pharmaceutical formulation. Drug absorption was measured in various solvent systems including 0.1N HCl (pH 1.2), acetate buffer (pH 4.5), phosphate buffer (pH 6.8) and distil water (pH 7.0). Method validation was performed as per official guidelines of ICH, 2005. High drug absorption was observed in 0.1N HCl medium with λ max of 261nm. The drug showed the good linearity from 20 to 60μg/mL solution concentration with the correlation coefficient linear regression equation Y= 0.1853 X + 0.1098 presenting R 2 value of 0.9998. The method accuracy was evaluated by the percent drug recovery, presents more than 99% drug recovery at three different levels assessed. The % RSD value <1 was computed for inter and intraday analysis indicating the high accuracy and precision of the developed technique. The developed method is robust because it shows no any significant variation in with minute changes. The LOD and LOQ values were assessed to be 2.2μg/mL and 6.6μg/mL respectively. The investigated method proved its sensitivity, precision and accuracy hence could be successfully used to estimate the CPM content in bulk and pharmaceutical matrix tablets.

Social defeat promotes a reactive endothelium in a brain region-dependent manner with increased expression of key adhesion molecules, selectins and chemokines associated with the recruitment of myeloid cells to the brain.

PubMed

Sawicki, C M; McKim, D B; Wohleb, E S; Jarrett, B L; Reader, B F; Norden, D M; Godbout, J P; Sheridan, J F

2015-08-27

Repeated social defeat (RSD) in mice causes myeloid cell trafficking to the brain that contributes to the development of prolonged anxiety-like behavior. Myeloid cell recruitment following RSD occurs in regions where neuronal and microglia activation is observed. Thus, we hypothesized that crosstalk between neurons, microglia, and endothelial cells contributes to brain myeloid cell trafficking via chemokine signaling and vascular adhesion molecules. Here we show that social defeat caused an exposure- and brain region-dependent increase in several key adhesion molecules and chemokines involved in the recruitment of myeloid cells. For example, RSD induced distinct patterns of adhesion molecule expression that may explain brain region-dependent myeloid cell trafficking. VCAM-1 and ICAM-1 mRNA expression were increased in an exposure-dependent manner. Furthermore, RSD-induced VCAM-1 and ICAM-1 protein expression were localized to the vasculature of brain regions implicated in fear and anxiety responses, which spatially corresponded to previously reported patterns of myeloid cell trafficking. Next, mRNA expression of additional adhesion molecules (E- and P-selectin, PECAM-1) and chemokines (CXCL1, CXCL2, CXCL12, CCL2) were determined in the brain. Social defeat induced an exposure-dependent increase in mRNA levels of E-selectin, CXCL1, and CXCL2 that increased with additional days of social defeat. While CXCL12 was unaffected by RSD, CCL2 expression was increased by six days of social defeat. Last, comparison between enriched CD11b(+) cells (microglia/macrophages) and enriched GLAST-1(+)/CD11b(-) cells (astrocytes) revealed RSD increased mRNA expression of IL-1β, CCL2, and CXCL2 in microglia/macrophages but not in astrocytes. Collectively, these data indicate that key mediators of leukocyte recruitment were increased in the brain vasculature following RSD in an exposure- and brain region-dependent manner. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

Social defeat promotes a reactive endothelium in a brain region-dependent manner with increased expression of key adhesion molecules, selectins and chemokines associated with the recruitment of myeloid cells to the brain

PubMed Central

Sawicki, Caroline M.; McKim, Daniel B.; Wohleb, Eric S.; Jarrett, Brant L.; Reader, Brenda F.; Norden, Diana M.; Godbout, Jonathan P.; Sheridan, John F.

2014-01-01

Repeated social defeat (RSD) in mice causes myeloid cell trafficking to the brain that contributes to the development of prolonged anxiety-like behavior. Myeloid cell recruitment following RSD occurs in regions where neuronal and microglia activation is observed. Thus, we hypothesized that crosstalk between neurons, microglia, and endothelial cells contributes to brain-myeloid cell trafficking via chemokine signaling and vascular adhesion molecules. Here we show that social defeat caused an exposure- and brain region-dependent increase in several key adhesion molecules and chemokines involved in the recruitment of myeloid cells. For example, RSD induced distinct patterns of adhesion molecule expression that may explain brain region-dependent myeloid cell trafficking. VCAM-1 and ICAM-1 mRNA expression were increased in an exposure-dependent manner. Furthermore, RSD-induced VCAM-1 and ICAM-1 protein expression were localized to the vasculature of brain regions implicated in fear and anxiety responses, which spatially corresponded to previously reported patterns of myeloid cell trafficking. Next, mRNA expression of additional adhesion molecules (E- and P-selectin, PECAM-1) and chemokines (CXCL1, CXCL2, CXCL12, CCL2) were determined in the brain. Social defeat induced an exposure-dependent increase in mRNA levels of E-selectin, CXCL1, and CXCL2 that increased with additional days of social defeat. While CXCL12 was unaffected by RSD, CCL2 expression was increased by six days of social defeat. Last, comparison between enriched CD11b+ cells (microglia/macrophages) and enriched GLAST-1+/CD11b− cells (astrocytes) revealed RSD increased mRNA expression of IL-1β, CCL2, and CXCL2 in microglia/macrophages but not in astrocytes. Collectively, these data indicate that key mediators of leukocyte recruitment were increased in the brain vasculature following RSD in an exposure- and brain-region dependent manner. PMID:25445193

Graphene-ZIF8 composite material as stationary phase for high-resolution gas chromatographic separations of aliphatic and aromatic isomers.

PubMed

Yang, Xiaohong; Li, Changxia; Qi, Meiling; Qu, Liangti

2016-08-19

This work presents the separation performance of graphene-ZIF8 (G-Z) composite material as stationary phase for capillary gas chromatography (GC). The G-Z stationary phase achieved high column efficiency of 5000 plates/m determined by n-dodecane (k=1.22) at 120°C and showed weakly polar nature. Importantly, it exhibited high selectivity and resolving capability for branched alkane isomers and aromatic positional isomers, showing clear advantages over the reported neat graphene and ZIF8. In addition, it attained high resolution for geometric cis-/trans-isomers. The G-Z column exhibited good column thermal stability up to 300°C and column repeatability with RSD values of retention times in the range of 0.01-0.19% for intra-day, 0.05-0.88% for inter-day and 0.66-5.6% for between-column, respectively, Moreover, the G-Z column was employed for the determination of minor impurity isomers in real reagent samples, which demonstrates its promising potential in GC applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Individual efforts to reduce salt intake in China, Japan, UK, USA: what did people achieve? The INTERMAP Population Study.

PubMed

Okuda, Nagako; Stamler, Jeremiah; Brown, Ian J; Ueshima, Hirotsugu; Miura, Katsuyuki; Okayama, Akira; Saitoh, Shigeyuki; Nakagawa, Hideaki; Sakata, Kiyomi; Yoshita, Katsushi; Zhao, Liancheng; Elliott, Paul

2014-12-01

Habitual high-salt intake raises blood pressure and risk of cardiovascular diseases. To prevent/control these risks, reduced salt diet (RSD) is recommended in many countries and some people report practicing it; however, little is known about actual achievement. This population-based study assessed level of 24-h dietary sodium intake of participants reporting RSD and others. Participants were 4680 men and women ages 40-59 years randomly selected from 17 populations in People's Republic of China (PRC), Japan, UK and USA, for an observational study on diet and blood pressure (INTERMAP). Daily sodium intake was determined by two timed 24-h urine collections. Antihypertensive treatment status and RSD were ascertained by questionnaire. Participants reporting RSD were few; 3.1% (Japan), 1.3% (PRC), 2.5% (UK), 7.2% (USA); 15.1, 7.9, 16.7 and 16.8% of people with treated hypertension. For those reporting RSD, 24-h urinary sodium excretion was significantly, but only modestly lower than for others, by 17.9 mmol/day (Japan), 56.7 (PRC) and 14.7 (USA), but higher by 10.5 in UK. Sodium intakes for participants reporting RSD remained higher than recommended; 181.0 mmol/day (Japan), 171.5 (PRC), 155.2 (UK) and 148.9 (USA). For these people, as for others, main sources of salt were processed foods in Japan, UK and USA; in PRC, salt added in preparation at home. Enhanced sustained efforts are needed to raise general awareness of the harmful effects of salt on health and the benefits of salt reduction. Population approaches are needed to reduce salt content of processed foods and restaurant meals.

Fast and high-efficiency magnetic surface imprinting based on microwave-accelerated reversible addition fragmentation chain transfer polymerization for the selective extraction of estrogen residues in milk.

PubMed

Chen, Fangfang; Wang, Jiayu; Lu, Ruicong; Chen, Huiru; Xie, Xiaoyu

2018-08-10

A novel microwave-accelerated reversible addition fragmentation chain transfer (RAFT) polymerization strategy has been introduced to shorten reaction time and improved polymerization efficiency of the conventional molecularly imprinting technology based on RAFT. Magnetic molecular imprinted polymers (MMIPs) were successfully synthesized much more efficiently using 17β-estradiol (E2) as a template for the determination of estrogen residues. The resultant MMIPs had well-defined thin imprinted film, favoring the fast mass transfer. Moreover, the reaction time, which was just 1/24 of the time taken by conventional heating, was significantly decreased, improving the reaction efficiency and reducing the probability of side reactions. Meanwhile, the obtained polymers have good capacity of 6.67 mg g -1 and satisfactory selectivity to template molecule with the imprinting factor of 5.11. As a result, a method combination of the resultant MMIPs as solid phase extraction sorbents and high-performance liquid chromatography was successfully set up to determinate three estrogen residues in milk samples. For E2, estrone, and estriol, the limit of detections were calculated to be 0.03, 0.08, and 0.06 ng mL -1 , respectively, and the limit of quantifications were 0.11, 0.27, and 0.21 ng mL -1 , respectively. At the spiked level of 1, 5, and 10 ng mL -1 , the recoveries of the three estrogens were ranged from 69.1% to 91.9% and the intra-day relative standard deviation (RSD) was less than 5.7%. In addition, the resultant MMIPs exhibited good reproducibility and reusability with the inter-batch RSD of 5.3% and the intra-batch RSD of 6.2%, respectively. Overall, the realization of this strategy facilitates the preparation of MMIPs with good architecture and high reaction efficiencies for the analysis of complicated real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Use of ICP/MS with ultrasonic nebulizer for routine determination of uranium activity ratios in natural water

USGS Publications Warehouse

Kraemer, T.F.; Doughten, M.W.; Bullen, T.D.

2002-01-01

A method is described that allows precise determination of 234U/238U activity ratios (UAR) in most natural waters using commonly available inductively coupled plasma/mass spectrometry (ICP/MS) instrumentation and accessories. The precision achieved by this technique (??0.5% RSD, 1 sigma) is intermediate between thermal ionization mass spectrometry (??0.25% RSID, 1 sigma) and alpha particle spectrometry (??5% RSD, 1 sigma). It is precise and rapid enough to allow analysis of a large number of samples in a short period of time at low cost using standard, commercially available quadrupole instrumentation with ultrasonic nebulizer and desolvator accessories. UARs have been analyzed successfully in fresh to moderately saline waters with U concentrations of from less than 1 ??g/L to nearly 100 ??g/L. An example of the uses of these data is shown for a study of surface-water mixing in the North Platte River in western Nebraska. This rapid and easy technique should encourage the wider use of uranium isotopes in surface-water and groundwater investigations, both for qualitative (e.g. identifying sources of water) and quantitative (e.g. determining end-member mixing ratios purposes.

Spectrophotometric determination of flucloxacillin and dicloxacillin in pure and dosage forms

NASA Astrophysics Data System (ADS)

El-Dien, F. A. Nour; Mohamed, Gehad G.; Farag, Eman Y. Z. A.

2006-05-01

A simple, rapid and accurate spectrophotometric method for the determination of antibiotic drugs, flucloxacillin (Fluclox) and dicloxacillin (Diclox), in pure form and different pharmaceutical preparations has been developed. The charge transfer (CT) reactions between Fluclox and Diclox as electron donors and 7,7,8,8-tetracyanoquinodimethane (TCNQ) and tetracyanoethylene (TCNE) as π-acceptors to give highly coloured complex species have been spectrophotometrically studied. The optimum experimental conditions for these CT reactions have been studied carefully. Beer's law is obeyed over the concentration ranges of 4-180 μg mL -1 and 4-70 μg mL -1 for Fluclox and Diclox drugs using TCNQ and TCNE reagents, respectively. The Sandell sensitivities ( S) are found to be 0.016-0.035 μg cm -2 and 0.011-0.016 μg cm -2 for Fluclox and Diclox, respectively, which indicate the high sensitivity of the proposed method. The relative standard deviations (R.S.D.: 0.08-0.49 and 0.15-0.80) for the determination of Fluclox and (R.S.D.: 0.05-0.75 and 0.13-0.75) for Diclox were obtained for four to six replicates using TCNQ and TCNE reagents, respectively, refer to the high accuracy and precision of the proposed method. These results are also confirmed by the between-day precision and the percent recovery of 99.90-100.1 and 99.60-100.4 for Fluclox and 99.90-100.5 and 99.40-100.1 for Diclox using TNCQ and TCNE reagents, respectively. The results obtained for the two reagents are comparable with those obtained by the official method.

Possible mechanism by which renal sympathetic denervation improves left ventricular remodelling after myocardial infarction.

PubMed

Zheng, Xiao-Xin; Li, Xiao-Yan; Lyu, Yong-Nan; He, Yi-Yu; Wan, Wei-Guo; Zhu, Hong-Ling; Jiang, Xue-Jun

2016-02-01

What is the central question of this study? The enzyme system that is responsible for extracellular matrix (ECM) turnover is the matrix metalloproteinases (MMPs), which can be blocked by the tissue inhibitors of MMPs (TIMPs). Whether renal sympathetic denervation (RSD) is able to ameliorate post-myocardial infarction left ventricular remodelling through attenuation of ECM via regulation of MMP activity and/or the MMP-TIMP complex remains unknown. What is the main finding and its importance? Renal sympathetic denervation has therapeutic effects on post-myocardial infarction left ventricular remodelling, probably by attenuating the ECM through regulation of the MMP9-TIMP1 complex in the transforming growth factor-β1 (a profibrotic cytokine that accelerates ECM remodelling after ischaemia) signalling pathway. Whether renal sympathetic denervation (RSD) is able to ameliorate post-myocardial infarction (post-MI) left ventricular (LV) remodelling by attenuation of the extracellular matrix via regulation of matrix metalloproteinase (MMP) activity and/or the MMP-tissue inhibitor of matrix metalloproteinase (TIMP) complex remains unknown. Sixty-five Sprague-Dawley rats were randomly divided into the following four groups: normal (N, n = 15), RSD (RSD, n = 15), myocardial infarction (MI, n = 15) and RSD 3 days after MI (MI3d+RSD, n = 20). The bilateral renal nerves were surgically denervated 3 days after MI had been induced by coronary artery ligation. Left ventricular function was assessed using echocardiography and a Millar catheter at 6 weeks post-MI. Plasma noradrenaline, angiotensin II and aldosterone, collagen volume fraction, transforming growth factor-β1 (TGF-β1), MMP2, MMP9 and TIMP1 in heart tissue were measured 6 weeks after MI. In rats with MI3d+RSD compared with MI rats, RSD improved systolic and diastolic function, resulting in an improvement in ejection fraction (P < 0.05), fractional shortening (P < 0.05) and LV internal dimension in systole (P < 0.05) and diastole (P < 0.05). Additionally, RSD treatment decreased left ventricular end-diastolic pressure (P < 0.05) and increased LV systolic pressure (P < 0.05) and maximal and minimal rate of LV pressure (both P < 0.05). Meanwhile, RSD reduced collagen content (P < 0.01). TIMP1 was upregulated (P < 0.05), whereas MMP2, MMP9 and TGF-β1 were downregulated in the LV of RSD-treated animals (P < 0.05). Renal sympathetic denervation has therapeutic effects on post-MI LV remodelling, probably owing to effects on the extracellular matrix by regulation of the MMP9-TIMP1 balance in the TGF-β1 signalling pathway. Renal sympathetic denervation may be considered as a non-pharmacological approach for the improvement of post-MI cardiac dysfunction. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

Development of a screening method for the determination of forty-nine priority pollutants in soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiang, P.H.T.

1985-01-01

An extraction procedure followed by capillary GC-MS analysis was used to determine soil pollutants. Dual pH solutions with methylene chloride were used as extraction solvent system. Both base/neutral and acidic fractions were analyzed on the same fused silica 30 meter SPB-1 (SE-30) column. A GC-FID with a 60 meter wide-bore SPB-1 glass capillary column was used for quantitative analysis due to its larger sample capacity and higher sensitivity. The precision and accuracy for 5.1 ppm (51 ..mu..g/10 g) concentration in zero soil was less than 25% RSD. A headspace technique was also developed for the determination of volatile compounds. Themore » same instrumental conditions and columns were used as in the extraction procedure. The precision and accuracy for 3 grams soil sample spiked with 5.1 ppm (52 ..mu..g/10 mL) pollutant mixture in a 20 mL vial was less than 3% RSD.« less

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chromium in water by graphite furnace atomic absorption spectrophotometry

USGS Publications Warehouse

McLain, B.J.

1993-01-01

Graphite furnace atomic absorption spectrophotometry is a sensitive, precise, and accurate method for the determination of chromium in natural water samples. The detection limit for this analytical method is 0.4 microg/L with a working linear limit of 25.0 microg/L. The precision at the detection limit ranges from 20 to 57 percent relative standard deviation (RSD) with an improvement to 4.6 percent RSD for concentrations more than 3 microg/L. Accuracy of this method was determined for a variety of reference standards that was representative of the analytical range. The results were within the established standard deviations. Samples were spiked with known concentrations of chromium with recoveries ranging from 84 to 122 percent. In addition, a comparison of data between graphite furnace atomic absorption spectrophotometry and direct-current plasma atomic emission spectrometry resulted in suitable agreement between the two methods, with an average deviation of +/- 2.0 microg/L throughout the analytical range.

Method performance and multi-laboratory assessment of a normal phase high pressure liquid chromatography-fluorescence detection method for the quantitation of flavanols and procyanidins in cocoa and chocolate containing samples.

PubMed

Robbins, Rebecca J; Leonczak, Jadwiga; Johnson, J Christopher; Li, Julia; Kwik-Uribe, Catherine; Prior, Ronald L; Gu, Liwei

2009-06-12

The quantitative parameters and method performance for a normal-phase HPLC separation of flavanols and procyanidins in chocolate and cocoa-containing food products were optimized and assessed. Single laboratory method performance was examined over three months using three separate secondary standards. RSD(r) ranged from 1.9%, 4.5% to 9.0% for cocoa powder, liquor and chocolate samples containing 74.39, 15.47 and 1.87 mg/g flavanols and procyanidins, respectively. Accuracy was determined by comparison to the NIST Standard Reference Material 2384. Inter-lab assessment indicated that variability was quite low for seven different cocoa-containing samples, with a RSD(R) of less than 10% for the range of samples analyzed.

Increased efficacy for in-house validation of real-time PCR GMO detection methods.

PubMed

Scholtens, I M J; Kok, E J; Hougs, L; Molenaar, B; Thissen, J T N M; van der Voet, H

2010-03-01

To improve the efficacy of the in-house validation of GMO detection methods (DNA isolation and real-time PCR, polymerase chain reaction), a study was performed to gain insight in the contribution of the different steps of the GMO detection method to the repeatability and in-house reproducibility. In the present study, 19 methods for (GM) soy, maize canola and potato were validated in-house of which 14 on the basis of an 8-day validation scheme using eight different samples and five on the basis of a more concise validation protocol. In this way, data was obtained with respect to the detection limit, accuracy and precision. Also, decision limits were calculated for declaring non-conformance (>0.9%) with 95% reliability. In order to estimate the contribution of the different steps in the GMO analysis to the total variation variance components were estimated using REML (residual maximum likelihood method). From these components, relative standard deviations for repeatability and reproducibility (RSD(r) and RSD(R)) were calculated. The results showed that not only the PCR reaction but also the factors 'DNA isolation' and 'PCR day' are important factors for the total variance and should therefore be included in the in-house validation. It is proposed to use a statistical model to estimate these factors from a large dataset of initial validations so that for similar GMO methods in the future, only the PCR step needs to be validated. The resulting data are discussed in the light of agreed European criteria for qualified GMO detection methods.

Single-side renal sympathetic denervation to treat malignant refractory hypertension in a solitary kidney patient.

PubMed

Ribichini, Flavio; Ferrara, Angela; Pighi, Michele; Pesarini, Gabriele; Gambaro, Alessia; Valvo, Enrico; Lupo, Antonio; Vassanelli, Corrado

2014-12-01

Renal sympathetic denervation (RSD) is emerging as a new therapeutic option for patients with severe hypertension refractory to medical therapy. Patients affected by renovascular or anatomical abnormalities have hitherto been systematically excluded from clinical trials with RSD because of concern about safety and the unknown efficacy of the procedure in this subgroup of patients. We describe the management of a case of RSD in a single-kidney patient with refractory hypertension; the patient had had a previous surgical right nephrectomy for renal cell carcinoma that subsequently required no other oncologic treatment. After multidisciplinary assessment, the patient underwent RSD. The procedure was performed through a 6F femoral access using the Symplicity™ RSD system (Medtronic, Mountain View, CA, USA). Radiofrequency was applied to the renal artery wall in 6 different points under general sedation with midazolam to control back pain caused by the procedure, that was performed without periprocedural complications. The patient was discharged 2 days later after a control of the vascular access site and routine biochemical examinations. The following 9-month follow up showed a significant reduction in blood pressure and stable renal function, without signs of renal damage. Our report confirms the feasibility of RSD in this delicate context, without evident negative effects on kidney function and with a significant reduction in blood pressure. Future studies are needed to fully clarify the value of RSD in single-kidney patients.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoegg, Edward D.; Barinaga, Charles J.; Hager, George J.

ABSTRACT In order to meet a growing need for fieldable mass spectrometer systems for precise elemental and isotopic analyses, the liquid sampling-atmospheric pressure glow discharge (LS-APGD) has a number of very promising characteristics. One key set of attributes that await validation deals with the performance characteristics relative to isotope ratio precision and accuracy. Due to its availability and prior experience with this research team, the initial evaluation of isotope ratio (IR) performance was performed on a Thermo Scientific Exactive Orbitrap instrument. While the mass accuracy and resolution performance for orbitrap analyzers are very well documented, no detailed evaluations of themore » IR performance have been published. Efforts described here involve two variables: the inherent IR precision and accuracy delivered by the LSAPGD microplasma and the inherent IR measurement qualities of orbitrap analyzers. Important to the IR performance, the various operating parameters of the orbitrap sampling interface, HCD dissociation stage, and ion injection/data acquisition have been evaluated. The IR performance for a range of other elements, including natural, depleted, and enriched uranium isotopes was determined. In all cases the precision and accuracy are degraded when measuring low abundance (<0.1% isotope fractions). In the best case, IR precision on the order of 0.1 %RSD can be achieved, with values of 1-3 %RSD observed for low-abundance species. The results suggest that the LSAPGD is a very good candidate for field deployable MS analysis and that the high resolving powers of the orbitrap may be complemented with a here-to-fore unknown capacity to deliver high-precision isotope ratios.« less

A HILIC-UHPLC-MS/MS untargeted urinary metabonomics combined with quantitative analysis of five polar biomarkers on osteoporosis rats after oral administration of Gushudan.

PubMed

Wu, Xiao; Huang, Yue; Sun, Jinghan; Wen, Yongqing; Qin, Feng; Zhao, Longshan; Xiong, Zhili

2018-01-01

A HILIC-UHPLC-MS/MS untargeted urinary metabonomic method combined with quantitative analysis of five potential polar biomarkers in rat urine was developed and validated, to further understand the anti-osteoporosis effect of Gushudan(GSD) and its mechanism on prednisolone-induced osteoporosis(OP) rats in this study. The metabolites were separated and identified on Waters BEH HILIC (2.1mm×100mm, 1.7μm) column using the Waters ACQUITY™ ultra performance liquid chromatography system (Waters Corporation, Milford, USA) coupled with a Micromass Quattro Micro™ API mass spectrometer (Waters Corp, Milford, MA, USA). Principal component analysis (PCA) was used to identify potential biomarkers. Primary potential polar biomarkers including creatinine, taurine, betaine, hypoxanthine and cytosine, which were related to energy metabolism, lipid metabolism and amino acid metabolism, were found in the untargeted metabonomic research. Moreover, these targeted biomarkers were further separated and quantified in multiple-reaction monitoring (MRM) with positive ionization mode, using tinidazole as internal standard (I.S.). Good linearities (r>0.99) were obtained for all the analytes with the low limit of quantification from 1.00 to 12.8μg/mL. The relative standard deviation (RSD) of the intra-day and inter-day precisions were within 15.0% and the accuracy ranged from -14.3% to 13.5%. The recovery was more than 85.0%. And the validated method was successfully applied to investigate the urine samples of the control group, prednisolone-induced osteoporosis model group and Gushudan-treatment group in rats. Compared to the control group, the level of creatinine, taurine, betaine, hypoxanthine and cytosine in the model group revealed a significant decrease trend (p<0.05), while the Gushudan-treatment group showed no statistically differences by an independent sample t-test. This paper provided a better understanding of the therapeutic effect and mechanism of GSD on prednisolone-induced osteoporosis rats. Copyright © 2017. Published by Elsevier B.V.

New magnetic graphene-based inorganic-organic sol-gel hybrid nanocomposite for simultaneous analysis of polar and non-polar organophosphorus pesticides from water samples using solid-phase extraction.

PubMed

Rashidi Nodeh, Hamid; Wan Ibrahim, Wan Aini; Kamboh, Muhammad Afzal; Sanagi, Mohd Marsin

2017-01-01

A new graphene-based tetraethoxysilane-methyltrimethoxysilane sol-gel hybrid magnetic nanocomposite (Fe 3 O 4 @G-TEOS-MTMOS) was synthesised, characterized and successfully applied in magnetic solid-phase extraction (MSPE) for simultaneous analysis of polar and non-polar organophosphorus pesticides from several water samples. The Fe 3 O 4 @G-TEOS-MTMOS nanocomposite was characterized using Fourier transform-infrared spectroscopy, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy and X-ray diffraction. Separation, determination and quantification were achieved using gas chromatography coupled with micro electron capture detector. Adsorption capacity of the sorbent was calculated using Langmuir equation. MSPE was linear in the range 100-1000 pg mL -1 for phosphamidon and dimethoate, and 10-100 pg mL -1 for chlorpyrifos and diazinon, with limit of detection (S/N = 3) of 19.8, 23.7, 1.4 and 2.9 pg mL -1 for phosphamidon, dimethoate, diazinon and chlorpyrifos, respectively. The LODs obtained is well below the maximum residual level (100 pg mL -1 ) as set by European Union for pesticides in drinking water. Acceptable precision (%RSD) was achieved for intra-day (1.3-8.7%, n = 3) and inter-day (7.6-17.8%, n = 15) analyses. Fe 3 O 4 @G-TEOS-MTMOS showed high adsorption capacity (54.4-76.3 mg g -1 ) for the selected OPPs. No pesticide residues were detected in the water samples analysed. Excellent extraction recoveries (83-105%) were obtained for the spiked OPPs from tap, river, lake and sea water samples. The newly synthesised Fe 3 O 4 @G-TEOS-MTMOS showed high potential as adsorbent for OPPs analysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Determination of indole-3-acetic acid and indole-3-butyric acid in mung bean sprouts using high performance liquid chromatography with immobilized Ru(bpy)3(2+)-KMnO4 chemiluminescence detection.

PubMed

Xi, Zhijun; Zhang, Zhujun; Sun, Yonghua; Shi, Zuolong; Tian, Wei

2009-07-15

A novel method for determination of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) in an extract from mung bean sprouts using high performance liquid chromatography (HPLC) with chemiluminescence (CL) detection is described. The method is based on the CL reaction of auxin (indole-3-acetic acid and indole-3-butyric acid) with acidic potassium permanganate (KMnO(4)) and tris(2,2'-bipyridyl)ruthenium(II), which was immobilized on the cationic ion-exchange resin. The chromatographic separation was performed on a Nucleosil RP-C18 column (i.d.: 250 mm x 4.6 mm, particle size: 5 microm, pore size: 100) with an isocratic mobile phase consisting of methanol-water-acetic acid (45:55:1, v/v/v). At a flow rate of 1.0 mL min(-1), the total run time was 20 min. Under the optimal conditions, the linear ranges were 5.0x10(-8) to 5.0x10(-6)g mL(-1) and 5.0x10(-7) to 1.0x10(-5)g mL(-1) for IAA and IBA, respectively. The detection limits were 2.0x10(-8)g mL(-1) and 2.0x10(-7)g mL(-1) for IAA and IBA, respectively. The relative standard deviation (RSD) of intra-day were 3.1% and 2.3% (n=11) for 2x10(-6)g mL(-1) IAA and 2x10(-6)g mL(-1) IBA; The relative standard deviations of inter-day precision were 6.9% and 4.9% for 2x10(-6)g mL(-1) IAA and 2x10(-6)g mL(-1) IBA. The proposed method had been successfully applied to the determination of auxin in mung bean sprouts.

Pharmacokinetics and pharmacodynamics of a novel Acetylcholinesterase Inhibitor, DMNG-3.

PubMed

Xin-Guo, Zhang; Kou, Fei; Guo-Di, Ma; Tang, Peng; Zhong-Duo, Yang

2016-01-01

DMNG-3(3β-Methyl-[2-(4-nitrophenoxy)ethyl]-amino]con-5-enine), is a new and the potentially most potent acetylcholinesterase inhibitor recently obtained from conessine by N-demethylation and nucleophilic substitution reaction. In the present study, a step-down passive avoidance test was used to investigate whether DMNG-3 could modulate impairment of learning and memory induced by scopolamine, and a high performance liquid chromatography(HPLC) method for the determination of DMNG-3 in biological samples was applied to study its pharmacokinetics and tissues distribution. Separation was achieved on C18 column using a mobile phase consisting methanol-water (70:30, v/v) at a flow rate of 1.0ml/min. The intra- and inter-day precisions were good and the RSD was all lower than 1.30%. The mean absolute recovery of DMNG-3 in plasma ranged from 88.55 to 96.45 %. Our results showed oral administration of DMNG-3(10,25,50 mg/kg/day) can significantly improve the latency and number of errors and had a positive effect of improvement of learning and memory in mice in passive avoidance tests. The elimination half-life (T1/2) was 14.07±1.29, 15.87±1.03h, and the total clearance (CL) values were 0.70±0.11, 0.78±0.13 L/h/kg, respectively. The pharmacokinetic studies showed that DMNG-3 has a slowly clearance and large distribution volume in experimental animals, and its disposition is linear over the range of doses tested. The liver, small intestine, stomach, and large intestine were the major distribution tissues of DMNG-3 in mice. It was found that DMNG-3 could be detected in brain, suggesting that DMNG-3 can cross the blood-brain barrier. The present study shows that DMNG-3 can be possible developed as a new drug for the treatment of Alzheimer's disease in the future.

Ultrasound assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography designated for bioavailability studies of felodipine combinations in rat plasma.

PubMed

Ahmed, Sameh; Atia, Noha N; Bakr Ali, Marwa Fathy

2017-03-01

Felodipine (FLD), a calcium channel antagonist, is commonly prescribed for the treatment of hypertension either with Metoprolol (MET) or Ramipril (RAM) in two different drug combinations. FLD has high plasma protein binding ability affecting its extraction recoveries from plasma samples. Hence, a specific ultrasound assisted dispersive liquid-liquid microextraction (UA-DLLME) method coupled with HPLC using photodiode array detector was developed and validated for the simultaneous determination of FLD, MET and RAM in rat plasma after oral administration of these combinations. The factors affecting UA-DLLME were carefully optimized. In this study, UA-DLLME method could provide simple and efficient plasma extraction procedures with superior recovery results. Under optimum condition, all target drugs were separated within 13min. The validation procedures was carried out in agreement with US-FDA guidelines and shown to be suitable for anticipated purposes. Linear calibration ranges were obtained in the range 0.05-2.0μgmL -1 for FLD and MET and 0.1-2.0μgmL -1 for RAM with detection limits of 0.013-0.031μgmL -1 for all the studied drug combinations. The%RSD for inter-day and intra-day precisions was in range of 0.63-3.85% and the accuracy results were in the range of 92.13-100.5%. The validated UA-DLLME-HPLC method was successfully applied for the bioavailability studies of FLD, MET and RAM. The pharmacokinetic parameters were calculated for all the investigated drugs in rats after single-dose administrations of two different drug combinations. Although FLD was bioequivalent in the two formulations, a small increase in plasma levels of MET and RAM was found in the presence of FLD. Copyright © 2017 Elsevier B.V. All rights reserved.

Development, Validation and Application of a Stability Indicating HPLC Method to Quantify Lidocaine from Polyethylene-co-Vinyl Acetate (EVA) Matrices and Biological Fluids.

PubMed

Bhusal, Prabhat; Sharma, Manisha; Harrison, Jeff; Procter, Georgina; Andrews, Gavin; Jones, David S; Hill, Andrew G; Svirskis, Darren

2017-09-01

An efficient and cost-effective quantification procedure for lidocaine by HPLC has been developed to estimate lidocaine from an EVA matrix, plasma, peritoneal fluid and intra-articular fluid (IAF). This method guarantees the resolution of lidocaine from the degradation products obtained from alkaline and oxidative stress. Chromatographic separation of lidocaine was achieved with a retention time of 7 min using a C18 column with a mobile phase comprising acetonitrile and potassium dihydrogen phosphate buffer (pH 5.5; 0.02 M) in the ratio of 26:74 at a flow rate of 1 mL min-1 with detection at 230 nm. Instability of lidocaine was observed to an oxidizing (0.02% H2O2) and alkaline environments (0.1 M NaOH). The calibration curve was found to be linear within the concentration range of 0.40-50.0 μg/mL. Intra-day and inter-day accuracy ranged between 95.9% and 99.1%, with precision (% RSD) below 6.70%. The limit of quantification and limit of detection were 0.40 μg/mL and 0.025 μg/mL, respectively. The simple extraction method described enabled the quantification of lidocaine from an EVA matrix using dichloromethane as a solvent. The assay and content uniformity of lidocaine within an EVA matrix were 103 ± 3.60% and 100 ± 2.60%, respectively. The ability of this method to quantify lidocaine release from EVA films was also demonstrated. Extraction of lidocaine from plasma, peritoneal fluid and IAF followed by HPLC analysis confirmed the utility of this method for ex vivo and in vivo studies where the calibration plot was found to be linear from 1.60 to 50.0 μg/mL. © Crown copyright 2017.

Simultaneous quantification and inhibitory effect on LDL oxidation of the traditional Korean medicine, Leejung-tang

PubMed Central

2014-01-01

Background Leejung-tang (LJT) is a traditional Korean herbal medicine for the treatment of gastrointestinal disorders. In this study, we performed quantification analysis of five marker components, liquiritin (1), ginsenoside Rg1 (2), ginsenoside Rb1 (3), glycyrrhizin (4), and 6-gingerol (5) in LJT using a high performance liquid chromatography-photodiode array (HPLC–PDA). In addition, we investigated the inhibitory effect on low-density lipoprotein (LDL) oxidation by the LJT sample. Methods Compounds 1–5 were separated within 35 min using a Gemini C18 column. The mobile phase used gradient elution with 1.0% (v/v) aqueous acetic acid (A) and 1.0% (v/v) acetic acid in acetonitrile (B). The flow rate was 1.0 mL/min and the detector was a photodiode array (PDA) set at 203 nm, 254 nm, and 280 nm. The inhibitory effect on LDL oxidation conduct an experiment on thiobarbituric acid reactive substance (TBARS) assay, relative electrophoretic mobility (REM) assay, and electrophoresis of ApoB fragmentation of LJT. Results Calibration curves of compounds 1–5 showed good linearity (r2 ≥0.9995) in different concentration ranges. The recoveries of compounds 1–5 were in the range of 98.90–103.39%, with relative standard deviations (RSD) below 3.0%. The RSDs (%) of intra-day and inter-day precision were 0.10–1.08% and 0.29–1.87%, respectively. The inhibitory effect of LJT on Cu2+-induced LDL oxidation was defined by TBARS assay (IC50: 165.7 μg/mL) and REM of oxLDL (decrease of 50% at 127.7 μg/mL). Furthermore LJT reduced the fragmentation of ApoB of oxLDL in a dose-dependent manner. Conclusions The established HPLC-PDA method will be helpful to improve quality control of LJT. In addition, LJT is a potential LDL oxidation inhibitor. PMID:24383717

Determination of N-acetylglucosamine in cosmetic formulations and skin test samples by hydrophilic interaction liquid chromatography and UV detection.

PubMed

Pedrali, Alice; Bleve, Mariella; Capra, Priscilla; Jonsson, Tobias; Massolini, Gabriella; Perugini, Paola; Marrubini, Giorgio

2015-03-25

N-Acetylglucosamine is an ingredient in pharmaceuticals, nutritional supplements and in cosmetics. N-Acetylglucosamine in cosmetics is expected to improve skin hydration, reparation, and to contribute as anti-wrinkle agent. This study reports on the validation and application of an HPLC method based on HILIC and UV detection for determining N-acetylglucosamine in cosmetics and in samples obtained after testing the skin exposed to cosmetics formulations. The chromatographic column used is a ZIC(®)-pHILIC (150 mm × 4.6 mm, 5 μm particle size) on which a mobile phase containing acetonitrile-aqueous KH2PO4 (70:30, v/v) 15 mM was applied in isocratic elution mode injecting 20 μl of sample at 0.5 ml/min constant flow-rate and 10±1°C column temperature. Under these conditions the total run time was 10 min and N-acetylglucosamine eluted baseline separated from all other compounds in the samples. Calibration in the range from 40 to 80 μg/ml allowed to assess the method linearity (R(2)>0.999) in a concentration range corresponding to about 50% to 120% of the expected levels of N-acetylglucosamine in the formulations. Precision expressed by RSD% was always better than 2% in intra-day and inter-day assays of authentic samples. Accuracy was in all cases within 95-105% of the expected concentration value in formulations containing N-acetylglucosamine. The sensitivity of the method was at the level of 10 μg/ml as limit of detection, and at 40 μg/ml as limit of quantitation. The application of the method to formulations containing solid lipid nanoparticles documents its usefulness in cosmetic quality control. The results witness that the method is also suitable for the determination of N-acetylglucosamine in samples obtained from skin test strips. Copyright © 2014 Elsevier B.V. All rights reserved.

[Comparison of efficacy between continuous positive airway pressure and renal artery sympathetic denervation by radiofrequency ablation in obstructive sleep apnea syndrome patients with hypertension].

PubMed

Zhao, Meng-meng; Tan, Xue-xue; Ding, Ning; Zhang, Xi-long

2013-04-23

To compare the efficacy of renal arterial sympathetic denervation (RSD) and continuous positive airway pressure (CPAP) in patients with coexisting moderate-to-severe obstructive sleep apnea syndrome (OSAS) and hypertension. Retrospective analysis was conducted for patients with coexisting moderate to severe OSAS and hypertension for the efficacy of RSD (RSD group, n = 15) and CPAP (CPAP group, n = 16). Comparison was made for polysomnographic parameters and 24 hours ambulatory blood pressure (Bp) between two groups. There was no significant difference in age, gender, body mass index, nocturnal apnea hypopnea index (AHI), mean and minimal pulse oxygen saturation (mean SpO2 and mini SpO2) between two groups. Compared with those at pre-treatment, the following changes were observed at Day 30 post-treatment: in RSD group, the nocturnal AHI and T90 statistically decreased (27 ± 14 vs 32 ± 12, 8.7% ± 7.8% vs 13.8% ± 13.1%, all P < 0.05) with a significant increase in mean SpO2 (94.3% ± 2.2% vs 93.9% ± 2.0%, P < 0.05) while mini SpO2 showed no significant difference (80.1% ± 6.2% vs 79.5% ± 4.7%, P > 0.05); in CPAP group during treatment, nocturnal AHI and the ratio of duration SpO2 < 90% to total sleep time (T90) were all significantly reduced (5 ± 3 vs 35 ± 12, 1.5% ± 1.2% vs 12.9% ± 6.3%, all P < 0.05) while mean SpO2 and mini SpO2 became significantly elevated (95.6% ± 1.4% vs 93.6% ± 1.7%, 89.2% ± 2.7% vs 79.1% ± 4.0%, all P < 0.05). Compared with RSD group, there was a significantly lower AHI (P = 0.000) but higher mean SpO2 and mini SpO2 (all P < 0.05) at Day 30 in CPAP group. At Day 30 in RSD and CPAP groups, the mean systolic blood pressure (MSBp) were (122 ± 9) and (130 ± 12) mm Hg (1 mm Hg = 0.133 kPa) respectively while the mean diastolic blood pressure (MDBp) (80 ± 8) and (83 ± 7) mm Hg respectively. All these were significantly lower than those at pre-treatment with MSBp (134 ± 20) mm Hg and MDBp (88 ± 14) mm Hg in RSD group and MSBp (136 ± 14) mm Hg and MDBp (87 ± 7) mm Hg in CPAP group. The extent of decrease in MSBp post-treatment was more remarkable in RSD group than that in CPAP group (P < 0.05). In moderate-to-severe OSAS patients with hypertension, both RSD and CPAP may improve sleep respiratory parameters and blood pressure to varying degrees. There is a more significant improvement of nocturnal AHI and SpO2 in CPAP group and more lower MSBp in RSD group.

Multi-GNSS precise point positioning (MGPPP) using raw observations

NASA Astrophysics Data System (ADS)

Liu, Teng; Yuan, Yunbin; Zhang, Baocheng; Wang, Ningbo; Tan, Bingfeng; Chen, Yongchang

2017-03-01

A joint-processing model for multi-GNSS (GPS, GLONASS, BDS and GALILEO) precise point positioning (PPP) is proposed, in which raw code and phase observations are used. In the proposed model, inter-system biases (ISBs) and GLONASS code inter-frequency biases (IFBs) are carefully considered, among which GLONASS code IFBs are modeled as a linear function of frequency numbers. To get the full rank function model, the unknowns are re-parameterized and the estimable slant ionospheric delays and ISBs/IFBs are derived and estimated simultaneously. One month of data in April, 2015 from 32 stations of the International GNSS Service (IGS) Multi-GNSS Experiment (MGEX) tracking network have been used to validate the proposed model. Preliminary results show that RMS values of the positioning errors (with respect to external double-difference solutions) for static/kinematic solutions (four systems) are 6.2 mm/2.1 cm (north), 6.0 mm/2.2 cm (east) and 9.3 mm/4.9 cm (up). One-day stabilities of the estimated ISBs described by STD values are 0.36 and 0.38 ns, for GLONASS and BDS, respectively. Significant ISB jumps are identified between adjacent days for all stations, which are caused by the different satellite clock datums in different days and for different systems. Unlike ISBs, the estimated GLONASS code IFBs are quite stable for all stations, with an average STD of 0.04 ns over a month. Single-difference experiment of short baseline shows that PPP ionospheric delays are more precise than traditional leveling ionospheric delays.

Development of a fully automated on-line solid phase extraction and high-performance liquid chromatography with diode array detection method for the pharmacokinetic evaluation of bavachinin: a study on absolute bioavailability and dose proportionality.

PubMed

Liu, Lei; Liu, Kang-Ning; Wen, Ya-Bin; Zhang, Han-Wen; Lu, Ya-Xin; Yin, Zheng

2012-04-15

A fully automated on-line solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) with diode array detection (DAD) method was developed for determination of bavachinin in mouse plasma. Analytical process was performed on two reversed-phase columns (SPE cartridge and analytical column) connected via a Valco 6-port switching valve. Plasma samples (10 μL) were injected directly onto a C18 SPE cartridge (MF Ph-1 C18, 10 mm × 4 mm, 5 μm) and the biological matrix was washed out for 2 min with the loading solvent (5 mM NaH(2)PO(4) buffer, pH 3.5) at a flow rate of 1 mL/min. By rotation of the switching valve, bavachinin was eluted from the SPE cartridge in the back-flush mode and transferred to the analytical column (Venusil MP C18, 4.6 mm × 150 mm, 5 μm) by the chromatographic mobile phase consisted of acetonitrile-5mM NaH(2)PO(4) buffer 65/35 (v/v, pH 3.5) at a flow rate of 1 mL/min. The complete cycle of the on-line SPE purification and chromatographic separation of the analyte was 13 min with UV detection performed at 236 nm. Calibration curve with good linearity (r=0.9997) was obtained in the range of 20-4000 ng/mL in mouse plasma. The intra-day and inter-day precisions (RSD) of bavachinin were in the range of 0.20-2.32% and the accuracies were between 98.47% and 102.95%. The lower limit of quantification (LLOQ) of the assay was 20 ng/mL. In conclusion, the established automated on-line SPE-HPLC-DAD method demonstrated good performance in terms of linearity, specificity, detection and quantification limits, precision and accuracy, and was successfully utilized to quantify bavachinin in mouse plasma to support the pharmacokinetic (PK) studies. The PK properties of bavachinin were characterized as rapid oral absorption, high clearance, and poor absolute bioavailability. Copyright © 2012. Published by Elsevier B.V.

Effect of renal sympathetic denervation on the progression of paroxysmal atrial fibrillation in canines with long-term intermittent atrial pacing.

PubMed

Wang, Xule; Huang, Congxin; Zhao, Qingyan; Huang, He; Tang, Yanhong; Dai, Zixuan; Wang, Xiaozhan; Guo, Zongwen; Xiao, Jinping

2015-04-01

The aim of the present study was to explore the effect of renal sympathetic denervation (RSD) on the progression of paroxysmal atrial fibrillation (AF) in canines with long-term intermittent atrial pacing. Nineteen beagles were randomly divided into sham-operated group (six dogs), control group (six dogs), and RSD group (seven dogs). Sham-operated group were implanted with pacemakers without pacing; control group were implanted with pacemakers with long-term intermittent atrial pacing; and RSD group underwent catheter-based RSD bilaterally and were simultaneously implanted with pacemakers. Atrial pacing was maintained for 8 h a day and a total of 12 weeks in the control group and RSD group. Echocardiography showed that the left atrial structure and function were significantly improved in the RSD group compared with the control group (P < 0.05). Compared with the control group, the RSD group had fewer incidences of AF and a shorter duration of AF (P < 0.05) after long-term intermittent atrial pacing. In addition to increased atrial effective refractory period (AERP) and AF cycle length, AERP dispersion and P-wave duration and dispersion were significantly decreased in the RSD group compared with the control group (P < 0.05). Atrial morphological evaluation suggested that fibrosis and ultrastructural changes induced by long-term intermittent atrial pacing were markedly suppressed in the RSD dogs compared with controls (P < 0.05). Immunohistochemistry results showed that connexin 43 distribution in RSD mid-myocardial was significantly fewer heterogeneous than that in control mid-myocardial (P < 0.05). Renal denervation inhibits the progression of paroxysmal AF, which might be related to the suppression of atrial electrophysiology and structural heterogeneity. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Determination of illegal adulteration of dietary supplements with synthetic hair-growth compounds by UPLC and LC-Q-TOF/MS.

PubMed

Lee, Ji Hyun; Kang, Gihaeng; Park, Han Na; Kim, Jihee; Kim, Nam Sook; Park, Seongsoo; Park, Sung-Kwan; Baek, Sun Young; Kang, Hoil

2018-02-01

In this study, we developed a UPLC-PDA and LC-Q-TOF/MS method to identify and measure the following prohibited substances that may be found in dietary supplements:triaminodil, minoxidil, bimatoprost, alimemazine, diphenylcyclopropenone, α-tradiol, finasteride, methyltestosterone, spironolatone, flutamide, cyproterone, dutasteride, and testosterone 17-propionate.The method was validated according to International Conference on Harmonization guidelines in terms of specificity, linearity, accuracy, precision, LOD, LOQ, recovery, and stability. The method was completely validated showing satisfactory data for all method validation parameters. The linearity was good (R 2  > 0.999) with intra- and inter-day precision values of 0.2-3.4% and 0.3-2.9%, respectively. Moreover, the intra- and inter-day accuracies were 87-102% and 86-103%, respectively, and the precision was better than 9.4% (relative standard deviation).Hence, the proposed method is precise and has high quality,and can be utilised to comprehensively and continually monitor illegal drug adulteration in various forms of dietary supplements. Furthermore, to evaluate the applicability of the proposed method, we analysed 13 hair-growth compounds in 78 samples including food and dietary supplements. Minoxidil and triaminodil were detected in capsules at concentrations of 4.69 mg/g and 6.54 mg/g. In addition, finasteride was detected in a tablet at 13.45 mg/g. In addition, the major characteristic fragment ions were confirmed once again using LC-Q-TOF/MS for higher accuracy.

Simultaneous determination of esculin and its metabolite esculetin in rat plasma by LC-ESI-MS/MS and its application in pharmacokinetic study.

PubMed

Li, Ying-yi; Song, Ye-ying; Liu, Chang-hui; Huang, Xiao-tao; Zheng, Xia; Li, Neng; Xu, Mei-li; Mi, Sui-qing; Wang, Ning-sheng

2012-10-15

A new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method operated in the negative electrospray ionization (ESI) switching mode has been developed and validated for the simultaneous determination of esculin and its metabolite esculetin in rat plasma. After addition of internal standards scopoletin, the plasma sample was pretreated by solid-phase extraction (SPE), and separated on a reversed phase C(18) column with a mobile phase of 0.01% formic acid in water (solvent A) and methanol (solvent B) using isocratic elution (A:B=20:80, v/v). The detection of target compounds was done in multiple reaction monitoring (MRM) mode. The MRM detection was operated in the negative ESI mode using the transitions of m/z 339.1 ([M-H](-))→176.7 for esculetin, m/z 176.9 ([M-H](-))→133.0 and m/z 191.0 ([M-H](-))→175.9 for scopoletin. The standard curves, which ranged from 25 to 3200 ng/mL for esculin with the lowest limit of quantification (LLOQ) of 0.25 ng/mL and from 1.25 to 160 ng/mL for esculetin with the LLOQ of 1.25 ng/mL, were fitted to a 1/x weighted quadratic regression model. The method also afforded satisfactory results in terms of the sensitivity, specificity, precision (intra- and inter-day, RSD<8.73%), accuracy, recovery as well as the stability of the analyte under various conditions. The method was successfully applied to study the pharmacokinetics of esculin and its metabolite esculetin in rat plasma after oral administration of esculin at a dose of 100mg/kg. Copyright © 2012 Elsevier B.V. All rights reserved.

Rapid and sensitive liquid chromatography-tandem mass spectrometric method for the quantitative determination of potentially harmful substance 5,5'-oxydimethylenebis (2-furfural) in traditional Chinese medicine injections.

PubMed

Zang, Qingce; Gao, Yang; Huang, Luojiao; He, Jiuming; Lin, Sheng; Jin, Hongtao; Zhang, Ruiping; Abliz, Zeper

2018-03-01

With the rapid development and wide application of traditional Chinese medicine injection (TCMI), a number of adverse events of some TCMIs have incessantly been reported and have drawn broad attention in recent years. Establishing effective and practical analytical methods for safety evaluation and quality control of TCMI can help to improve the safety of TCMIs in clinical applications. In this study, a sensitive and rapid high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed and validated for the quantitative determination of potentially harmful substance 5,5'-oxydimethylenebis (2-furfural, OMBF) in TCMI samples. Chromatographic separation was performed on a C18 reversed-phase column (150 mm × 2.1 mm, 5 µm) by gradient elution, using methanol-water containing 0.1% formic acid as mobile phase at the flow rate of 0.3 mL/min. MS/MS detection was performed on a triple quadrupole mass spectrometer with positive electrospray ionization in the multiple reaction-monitoring mode. The method was sensitive with a limit of quantification of 0.3 ng/mL and linear over the range of 0.3-30 ng/mL ( r =0.9998). Intra- and inter-day precision for analyte was <9.52% RSD with recoveries in the range 88.0-109.67% at three concentration levels. The validated method was successfully applied to quantitatively determine the compound OMBF in TCMIs and glucose injections. Our study indicates that this method is simple, sensitive, practicable and reliable, and could be applied for safety evaluation and quality control of TCMIs and glucose injections.

A cost effective hydrogel test kit for pre and post blast trinitrotoluene.

PubMed

Choodum, Aree; Malathong, Khanitta; NicDaeid, Niamh; Limsakul, Wadcharawadee; Wongniramaikul, Worawit

2016-09-01

A cost effective hydrogel test kit was successfully developed for the detection of pre- and post-blast trinitrotoluene (TNT). A polyvinyl alcohol (PVA) hydrogel matrix was used to entrap the potassium hydroxide (KOH) colourimetric reagent. The easily portable test kit was fabricated in situ in a small tube to which the sample could be added directly. The test kit was used in conjunction with digital image colourimetry (DIC) to demonstrate the rapid quantitative analysis of TNT in a test soil sample. The built-in digital camera of an iPhone was used to capture digital images of the colourimetric products from the test kit. Red-Green-Blue (RGB) colour data from the digital images of TNT standard solutions were used to establish a calibration graph. The validation of the DIC method indicated excellent inter day precision (0.12-3.60%RSD) and accuracy (93-108% relative accuracy). Post-blast soil samples containing TNT were analysed using the test kit and were in good agreement with spectrophotometric analysis. The intensity of the RGB data from the TNT complex deviated by +6.3%, +5.1%, and -4.9% after storage of the test kits in a freezer for 3 months. The test kit was also reusable for up to 12 times with only -5.4%, +0.3%, and +4.0% deviations. The hydrogel test kit was applied in the detection of trace explosive residues at the scene of the recent Bangkok bombing at the Ratchaprasong intersection and produced positive results for TNT demonstrating its operational field application as a rapid and cost effective quantitative tool for explosive residue analysis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Comparatively evaluating the pharmacokinetic of fifteen constituents in normal and blood deficiency rats after oral administration of Xin-Sheng-Hua Granule by UPLC-MS/MS.

PubMed

Pang, Han-Qing; Tang, Yu-Ping; Cao, Yu-Jie; Tan, Ya-Jie; Jin, Yi; Shi, Xu-Qin; Huang, Sheng-Liang; Sun, Da-Zheng; Sun, Jin; Tang, Zhi-Shu; Duan, Jin-Ao

2017-09-01

Xin-Sheng-Hua Granule (XSHG), a famous traditional Chinese medicine prescription, are clinically applied for the treatment of postpartum disease through nourishing blood and promoting blood circulation. In this investigation, a multi-constituents (trigonelline, stachydrine hydrochloride, hydroxysafflor yellow A, chlorogenic acid, amygdalin, leonurine, liquiritin, ferulic acid, senkyunolide I, senkyunolide H, glycyrrhizic acid, senkyunolide A, ligustilide, butylidenephthalide and glycyrrhetinic acid) pharmacokinetic study of XSHG was conducted for the first time. These fifteen constituents in both normal and blood deficiency rat plasma were monitored by using the established and validated ultra-high-performance liquid chromatography coupled with a triple quadrupole electrospray tandem mass spectrometry (UPLC-TQ-MS/MS) method. The samples were prepared through removing protein from plasma with three volumes of methanol. Sufficient separation of target constituents and internal standards (chloramphenicol and clarithromycin) was obtained on a Thermo Scientific Hypersil GOLD column (100mm×3mm, 1.9μm) within a 20min gradient elution (0.1% formic acid aqueous - acetonitrile). Multiple reaction monitoring (MRM) mode was applied to monitor target analytes in both positive and negative electrospray ionization. For the fifteen selected target analytes, this method was fully validated with excellent linearity (r≥0.9925), satisfactory intra- and inter-day precisions (RSD≤11.87%), as well as good accuracies (RE, between -12.84 and 11.69). And the stabilities, matrix effects and extraction recoveries of the rat plasma samples were also within acceptable limits (RSD<15%). Compared to normal group, the pharmacokinetics of major active constituents (except liquiritin and glycyrrhetinic acid) had significant differences (P<0.05) in the model rats, indicated that several metabolite enzymes activities could be altered at disease condition. Copyright © 2017 Elsevier B.V. All rights reserved.

Simple and rapid quantification of vancomycin in serum, urine and peritoneal/pleural effusion via UHPLC-MS/MS applicable to personalized antibiotic dosing research.

PubMed

Javorska, Lenka; Krcmova, Lenka Kujovska; Solich, Petr; Kaska, Milan

2017-08-05

Management of the therapy of life-threatening bacterial infection is extremely based on an optimal antibiotic treatment. Achieving the correct vancomycin dosage in blood and target tissues can be complicated in special situations, e.g., where large fluid sequestration and/or acute renal failure occur. A UHPLC-MS/MS method operating in electrospray (ESI) positive ion mode was applied for the determination of vancomycin in serum, urine and peritoneal/pleural effusion. Sample pretreatment was composed of dilution and simple protein precipitation where only a small volume (50μL) of serum, urine or peritoneal/pleural effusion was required. The separation of vancomycin was performed on a Meteoric Core C18 BIO column (100×4.6mm, 2.7μm) by gradient elution with 0.1% formic acid in water and acetonitrile. The total time of analysis was 4.5min. The method was found to be linear in the range of 2-60μM (or 0.5-10μM) for serum, 0.27-10μM (or 2-60μM) for peritoneal/pleural effusion and 25-300μM for urine, which was adequate for the determination of vancomycin in patient samples. The intra- and inter-day precision was below 8% RSD, and accuracy was from 89 to 104%. The UHPLC/MS-MS method offers a fast and reliable approach to determine vancomycin concentrations in three different human body fluid samples (serum, urine and peritoneal/pleural effusion) with a simple sample pretreatment that was the same for all selected specimens. This method should be applicable to large sample series in clinical (pharmacokinetic/pharmacodynamic) studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification and analysis of gastrodin and its five metabolites using ultra fast liquid chromatography electrospray ionization tandem mass spectrometry to investigate influence of multiple-dose and food.

PubMed

Jia, Yuanwei; Shen, Jie; Li, Xin; Xie, Haitang; Wang, Junsong; Luo, Jun; Wang, Kelvin D G; Liu, Qingwang; Kong, Lingyi

2014-09-05

A reliable and highly sensitive ultra performance liquid chromatography electrospray ionization tandem mass spectrometry (UFLC-ESI-MS/MS) analytical method was developed for identification and quantification of gastrodin (GAS) and its metabolites in rat plasma. Five metabolites were identified: p-formylphenyl-β-d-glucopyranoside (M1), p-hydroxybenzonic acid (M2), p-hydroxybenzyl alcohol (M3), p-formaldehydephenyl-β-d-glucopyranoside (M4), p-hydroxybenzaldehyde (M5). The molecular structures of metabolites were proposed based on the characters of their precursor ions, product ions and chromatographic retention time. Four of them were reported firstly in rat plasma. This method involved the addition of bergeninum as the internal standard (IS), UFLC separation, and quantification by MS/MS system using negative electrospray ionization in the multiple reaction monitoring (MRM) mode. The lower limit of quantification of gastrodin and five metabolites were all 1ng/mL. The method was linear in the concentration range of 0.001-10μg/mL. The intra- and inter-day precisions (R.S.D %) were within 15.0% for all analytes. No interference was noted due to endogenous substances. All analytes were stable in rat plasma stored at room temperature and 4°C for at least 4h, -20°C combined with three freeze-thaw cycles for at least 1 month. By this method, the influence of multiple-dose and food on the pharmacokinetics behaviors of GAS and its metabolites were studied for the first time. We hope pharmacokinetic data of present study may inspire rational clinical usage of GAS. Copyright © 2014 Elsevier B.V. All rights reserved.

A rapid MCM-41 dispersive micro-solid phase extraction coupled with LC/MS/MS for quantification of ketoconazole and voriconazole in biological fluids.

PubMed

Yahaya, Noorfatimah; Sanagi, Mohd Marsin; Abd Aziz, Noorizan; Wan Ibrahim, Wan Aini; Nur, Hadi; Loh, Saw Hong; Kamaruzaman, Sazlinda

2017-02-01

A rapid dispersive micro-solid phase extraction (D-μ-SPE) combined with LC/MS/MS method was developed and validated for the determination of ketoconazole and voriconazole in human urine and plasma samples. Synthesized mesoporous silica MCM-41 was used as sorbent in d-μ-SPE of the azole compounds from biological fluids. Important D-μ-SPE parameters, namely type desorption solvent, extraction time, sample pH, salt addition, desorption time, amount of sorbent and sample volume were optimized. Liquid chromatographic separations were carried out on a Zorbax SB-C 18 column (2.1 × 100 mm, 3.5 μm), using a mobile phase of acetonitrile-0.05% formic acid in 5 mm ammonium acetate buffer (70:30, v/v). A triple quadrupole mass spectrometer with positive ionization mode was used for the determination of target analytes. Under the optimized conditions, the calibration curves showed good linearity in the range of 0.1-10,000 μg/L with satisfactory limit of detection (≤0.06 μg/L) and limit of quantitation (≤0.3 μg/L). The proposed method also showed acceptable intra- and inter-day precisions for ketoconazole and voriconazole from urine and human plasma with RSD ≤16.5% and good relative recoveries in the range 84.3-114.8%. The MCM-41-D-μ-SPE method proved to be rapid and simple and requires a small volume of organic solvent (200 μL); thus it is advantageous for routine drug analysis. Copyright © 2016 John Wiley & Sons, Ltd.

Simultaneous determination of AM80 (tamibarotene) and WJD-A-1 in rat plasma by ultra high-performance liquid chromatography-tandem mass spectrometry and its application to a pharmacokinetic study.

PubMed

Leng, Ping; Yang, Zhao; Ma, Baohua; Li, Jing; Sun, Jialin; Xie, Yiming; Sun, Yong

2018-03-05

A compound (WJD-A-1) was previously reported as a candidate prodrug of Am80 (tamibarotene), which was approved in Japan in 2005 as a therapeutic agent for recurrent refractory acute promyelocytic leukaemia. A rapid, selective and sensitive ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the first time to simultaneously determine WJD-A-1 and its major phase-I metabolites AM80 in rat plasma. After a simple sample preparation procedure by protein precipitation with methanol and acetonitrile, WJD-A-1, AM80 and the internal standard were chromatographed on an ACQUITY UPLC TM BEH C 18 column. The mobile phase consisted of methanol-0.1% formic acid (80:20, v/v) and the flow rate was 0.20 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI) source. Each plasma sample was chromatographed within 2.6 min. The linear calibration curves for WJD-A-1 and the AM80 were obtained in the concentration range of 5.40-5.40 × 10 3 and 5.08-5.08 × 10 3  ng/mL, respectively (r ≥ 0.99). The intra- and inter-day precision (relative standard deviation, RSD) values were less than 8% and the accuracy (relative error, RE) was within ±6.8%, determined from quality control (QC) samples for the analytes. The method herein described was fully validated and successfully applied to pharmacokinetic study of WJD-A-1 following an intravenous administration of 300 μg/kg WJD-A-1 to rats.

A LC-MS/MS method to monitor the concentration of HYD-PEP06, a RGD-modified Endostar mimetic peptide in rat blood.

PubMed

Dong, Xiaona; Zhang, Yiwei; Meng, Zhiyun; Zhu, Xiaoxia; Gan, Hui; Gu, Ruolan; Wu, Zhuona; Li, Jian; Zheng, Ying; Yang, Baofeng; Dou, Guifang

2018-05-29

HYD-PEP06 is a novel RGD-modified Endostar mimetic peptide with 30 amino acids that is intended to suppress the formation of neoplasm vessels. This assay was developed and validated to monitor the level of the peptide HYD-PEP06 in rat blood, using liquid chromatography tandem mass spectrometry (LC-MS/MS). HYD-PEP10, another peptide similar to the analyte, was used as an internal standard (IS). A triple quadrupole mass spectrometry in Multiple Reaction Monitoring (MRM) mode and an electrospray interface (ESI) in the positive mode were used for MS analysis. The analysis was optimized with addition of 0.3% formic acid (FA) into the mobile phase as well as with a needle washing solution to overcome the carryover effect. In addition, the carryover was reduced by optimizing the mobile phase gradient. Methanol was used as a diluent of working solutions to avoid any adsorption. Methanol:acetonitrile (1:1, v:v) containing 0.3% FA was employed to precipitate the blood samples. Unknown blood samples must be placed in ice bath immediately, and precipitating agents should be added within 30 min to ensure the stability of blood samples. The assay was established and validated. This method showed a good linear relationship for the HYD-PEP06 in the range of 10 ng·mL -1 to 2000 ng·mL -1 , with R > 0.99. HYD-PEP06 was determined with accuracy values (RE%) of -5.06%-8.54%, intra- and inter-day precisions (RSD%) of 3.13%-4.87% and 4.81%-9.42%. The method was successfully in monitoring the concentration of HYD-PEP06 in rat blood. Copyright © 2018 Elsevier B.V. All rights reserved.

Simultaneous determination of trantinterol and its metabolites in rat urine and feces by liquid chromatography-tandem mass spectrometry.

PubMed

Li, Kunjie; Wang, Yanjuan; Zhang, Lili; Qin, Feng; Guo, Xingjie; Li, Famei

2013-09-01

A highly selective and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of trantinterol (SPFF) and its major metabolites for the first time. The analytes were extracted from rat urine and feces samples by liquid-liquid extraction (LLE) and determined in multiple reaction monitoring (MRM) mode with clenbuterol as the internal standard. Chromatographic separation was achieved on a Venusil ASB C8 column (2.1mm×100mm, 3μm), with the mobile phase consisted of methanol-0.2% formic acid (30:70, v/v) at the flow rate of 0.2mL/min. Each sample was chromatographed within 5min. This method has a lower limit of quantification (LLOQ) of 0.450, 1.05, 1.35, 0.904 and 1.36ng/mL for trantinterol (SPFF), arylhydroxylamine trantinterol (N-OH-SPFF), tert-butyl hydroxylated trantinterol (Tert-OH-SPFF), 1-carbonyl trantinterol (SPFF-COOH) and 3-methyl sulfone-dechloro-trantinterol (SPFF-SO2CH3) in rat urine, and 0.450, 1.35 and 0.904ng/mL for SPFF, Tert-OH-SPFF and SPFF-COOH in rat feces, respectively. The linear correlation coefficients were greater than 0.990. The intra- and inter-day precision (relative standard deviation, RSD) values were below 15% and the accuracy (relative error, RE) was -9.9% to 11% at three quality control levels. The method has been successfully applied to the excretion study following an oral administration of 1mg/kg trantinterol to rats. Copyright © 2013 Elsevier B.V. All rights reserved.

Automation of ⁹⁹Tc extraction by LOV prior ICP-MS detection: application to environmental samples.

PubMed

Rodríguez, Rogelio; Leal, Luz; Miranda, Silvia; Ferrer, Laura; Avivar, Jessica; García, Ariel; Cerdà, Víctor

2015-02-01

A new, fast, automated and inexpensive sample pre-treatment method for (99)Tc determination by inductively coupled plasma-mass spectrometry (ICP-MS) detection is presented. The miniaturized approach is based on a lab-on-valve (LOV) system, allowing automatic separation and preconcentration of (99)Tc. Selectivity is provided by the solid phase extraction system used (TEVA resin) which retains selectively pertechnetate ion in diluted nitric acid solution. The proposed system has some advantages such as minimization of sample handling, reduction of reagents volume, improvement of intermediate precision and sample throughput, offering a significant decrease of both time and cost per analysis in comparison to other flow techniques and batch methods. The proposed LOV system has been successfully applied to different samples of environmental interest (water and soil) with satisfactory recoveries, between 94% and 98%. The detection limit (LOD) of the developed method is 0.005 ng. The high durability of the resin and its low amount (32 mg), its good intermediate precision (RSD 3.8%) and repeatability (RSD 2%) and its high extraction frequency (up to 5 h(-1)) makes this method an inexpensive, high precision and fast tool for monitoring (99)Tc in environmental samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Application of a microplate-based ORAC-pyrogallol red assay for the estimation ofantioxidant capacity: First Action 2012.03.

PubMed

Ortiz, Rocío; Antilén, Mónica; Speisky, Hernán; Aliaga, Margarita E; López-Alarcón, Camilo; Baugh, Steve

2012-01-01

A method was developed for microplate-based oxygen radicals absorbance capacity (ORAC) using pyrogallol red (PGR) as probe (ORAC-PGR). The method was evaluated for linearity, precision, and accuracy. In addition, the antioxidant capacity of commercial beverages, such as wines, fruit juices, and iced teas, was measured. Linearity of the area under the curve (AUC) versus Trolox concentration plots was [AUC = (845 +/- 110) + (23 +/- 2) [Trolox, microM]; R = 0.9961, n = 19]. Analyses showed better precision and accuracy at the highest Trolox concentration (40 microM) with RSD and recovery (REC) values of 1.7 and 101.0%, respectively. The method also showed good linearity for red wine [AUC = (787 +/- 77) + (690 +/- 60) [red wine, microL/mL]; R = 0.9926, n = 17], precision and accuracy with RSD values from 1.4 to 8.3%, and REC values that ranged from 89.7 to 103.8%. Red wines showed higher ORAC-PGR values than white wines, while the ORAC-PGR index of fruit juices and iced teas presented a wide range of results, from 0.6 to 21.6 mM of Trolox equivalents. Product-to-product variability was also observed for juices of the same fruit, showing the differences between brands on the ORAC-PGR index.

Preliminary Figures of Merit for Isotope Ratio Measurements: The Liquid Sampling-Atmospheric Pressure Glow Discharge Microplasma Ionization Source Coupled to an Orbitrap Mass Analyzer

NASA Astrophysics Data System (ADS)

Hoegg, Edward D.; Barinaga, Charles J.; Hager, George J.; Hart, Garret L.; Koppenaal, David W.; Marcus, R. Kenneth

2016-08-01

In order to meet a growing need for fieldable mass spectrometer systems for precise elemental and isotopic analyses, the liquid sampling-atmospheric pressure glow discharge (LS-APGD) has a number of very promising characteristics. One key set of attributes that await validation deals with the performance characteristics relative to isotope ratio precision and accuracy. Owing to its availability and prior experience with this research team, the initial evaluation of isotope ratio (IR) performance was performed on a Thermo Scientific Exactive Orbitrap instrument. While the mass accuracy and resolution performance for Orbitrap analyzers are well-documented, no detailed evaluations of the IR performance have been published. Efforts described here involve two variables: the inherent IR precision and accuracy delivered by the LS-APGD microplasma and the inherent IR measurement qualities of Orbitrap analyzers. Important to the IR performance, the various operating parameters of the Orbitrap sampling interface, high-energy collisional dissociation (HCD) stage, and ion injection/data acquisition have been evaluated. The IR performance for a range of other elements, including natural, depleted, and enriched uranium isotopes was determined. In all cases, the precision and accuracy are degraded when measuring low abundance (<0.1% isotope fractions). In the best case, IR precision on the order of 0.1% RSD can be achieved, with values of 1%-3% RSD observed for low-abundance species. The results suggest that the LS-APGD is a promising candidate for field deployable MS analysis and that the high resolving powers of the Orbitrap may be complemented with a here-to-fore unknown capacity to deliver high-precision IRs.

[Determination of four bisphenolic compounds in drinking water by liquid chromatography-tandem mass spectrometry].

PubMed

Hu, Xiaojian; Zhang, Haijing; Wang, Xiaohong; Ding, Changming; Lin, Shaobin

2015-05-01

To simultaneously determine the four bisphenolic compounds (bisphenol F, bisphenol A, tetrachlorobisphenol A and tetrabromobisphenol A) in drinking water by liquid chromatography tandem mass spectrometry. 200 ml water sample was extracted by solid-phase extraction, eluted with methanol and analyzed by liquid chromatography tandem mass spectrometry under the MRM mode. The separation was carried out on a T3 column (2.1 mm x 150 mm, 3 μm). The limits of detection for the four bisphenolic compounds were in the range of 0.20 - 5.5 ng/L. The mean recoveries at the two spiked levels were 87.1% - 109.0% with the intra-day precision between 6.3% - 12.4% and inter-day precision between 4.5% - 15.4%. The method was applied for determination of 15 water samples. The method was sensitive, precise and accurate.

Quantitative determination of insulin entrapment efficiency in triblock copolymeric nanoparticles by high-performance liquid chromatography.

PubMed

Xu, Xiongliang; Fu, Yao; Hu, Haiyan; Duan, Yourong; Zhang, Zhirong

2006-04-11

A rapid and effective isocratic chromatographic procedure was described in this paper for the determination of insulin entrapment efficiency (EE) in triblock copolymeric nanoparticles using reversed-phase high-performance liquid chromatography (RP-HPLC) with an ultraviolet/visible detector at low flow rate. The method has been developed on a Shimadzu Shim-pack VP-ODS column (150 mm x 4.6 mm, 5 microm, Chiyoda-Ku, Tokyo, Japan) using a mixture of 0.2 M sodium sulfate anhydrous solution adjusted to pH 2.3 with phosphoric acid and acetonitrile (73:27, v/v) as mobile phase at the flow rate of 0.8 ml min(-1) and a 214 nm detection. The method was validated in terms of selectivity, linearity, precision, accuracy, solution stability, limit of detection (LOD) and limit of quantification (LOQ). The calibration curve was linear in the concentration range of 2.0-500.0 microg ml(-1), and the limits of detection and quantitation were 8 and 20 ng, respectively. The mean recovery of insulin from spiked samples, in a concentration range of 8-100 microg ml(-1), was 98.96% (R.S.D.= 2.51%, n = 9). The intra- and inter-assay coefficients of variation were less than 2.24%. The proposed method has the advantages of simple pretreatment, rapid isolation, high specificity and precision, which can be used for direct analysis of insulin in commercially available raw materials, formulations of nanoparticles, and drug release as well as stability studies.

A novel gene, RSD-3/HSD-3.1, encodes a meiotic-related protein expressed in rat and human testis.

PubMed

Zhang, Xiaodong; Liu, Huixian; Zhang, Yan; Qiao, Yuan; Miao, Shiying; Wang, Linfang; Zhang, Jianchao; Zong, Shudong; Koide, S S

2003-06-01

The expression of stage-specific genes during spermatogenesis was determined by isolating two segments of rat seminiferous tubule at different stages of the germinal epithelium cycle delineated by transillumination-delineated microdissection, combined with differential display polymerase chain reaction to identify the differential transcripts formed. A total of 22 cDNAs were identified and accepted by GenBank as new expressed sequence tags. One of the expressed sequence tags was radiolabeled and used as a probe to screen a rat testis cDNA library. A novel full-length cDNA composed of 2228 bp, designated as RSD-3 (rat sperm DNA no.3, GenBank accession no. AF094609) was isolated and characterized. The reading frame encodes a polypeptide consisting of 526 amino acid residues, containing a number of DNA binding motifs and phosphorylation sites for PKC, CK-II, and p34cdc2. Northern blot of mRNA prepared from various tissues of adult rats showed that RSD-3 is expressed only in the testis. The initial expression of the RSD-3 gene was detected in the testis on the 30th postnatal day and attained adult level on the 60th postnatal day. Immunolocalization of RSD-3 in germ cells of rat testis showed that its expression is restricted to primary spermatocytes, undergoing meiosis division I. A human testis homologue of RSD-3 cDNA, designated as HSD-3.1 (GenBank accession no. AF144487) was isolated by screening the Human Testis Rapid-Screen arrayed cDNA library panels by RT-PCR. The exon-intron boundaries of HSD-3.1 gene were determined by aligning the cDNA sequence with the corresponding genome sequence. The cDNA consisted of 12 exons that span approximately 52.8 kb of the genome sequence and was mapped to chromosome 14q31.3.

Mn/Ca intra- and inter-test variability in the benthic foraminifer Ammonia tepida

NASA Astrophysics Data System (ADS)

Petersen, Jassin; Barras, Christine; Bézos, Antoine; La, Carole; de Nooijer, Lennart J.; Meysman, Filip J. R.; Mouret, Aurélia; Slomp, Caroline P.; Jorissen, Frans J.

2018-01-01

The adaptation of some benthic foraminiferal species to low-oxygen conditions provides the prospect of using the chemical composition of their tests as proxies for bottom water oxygenation. Manganese may be particularly suitable as such a geochemical proxy because this redox element is soluble in reduced form (Mn2+) and hence can be incorporated into benthic foraminiferal tests under low-oxygen conditions. Therefore, intra- and inter-test differences in foraminiferal Mn/Ca ratios may hold important information about short-term variability in pore water Mn2+ concentrations and sediment redox conditions. Here, we studied Mn/Ca intra- and inter-test variability in living individuals of the shallow infaunal foraminifer Ammonia tepida sampled in Lake Grevelingen (the Netherlands) in three different months of 2012. The deeper parts of this lake are characterized by seasonal hypoxia/anoxia with associated shifts in microbial activity and sediment geochemistry, leading to seasonal Mn2+ accumulation in the pore water. Earlier laboratory experiments with similar seawater Mn2+ concentrations as encountered in the pore waters of Lake Grevelingen suggest that intra-test variability due to ontogenetic trends (i.e. size-related effects) and/or other vital effects occurring during calcification in A. tepida (11-25 % relative SD, RSD) is responsible for part of the observed variability in Mn/Ca. Our present results show that the seasonally highly dynamic environmental conditions in the study area lead to a strongly increased Mn/Ca intra- and inter-test variability (average of 45 % RSD). Within single specimens, both increasing and decreasing trends in Mn/Ca ratios with size are observed. Our results suggest that the variability in successive single-chamber Mn/Ca ratios reflects the temporal variability in pore water Mn2+. Additionally, active or passive migration of the foraminifera in the surface sediment may explain part of the observed Mn/Ca variability.

Molecularly imprinted polymer-sol-gel tablet toward micro-solid phase extraction: II. Determination of amphetamine in human urine samples by liquid chromatography-tandem mass spectrometry.

PubMed

El-Beqqali, Aziza; Andersson, Lars I; Jeppsson, Amin Dadoun; Abdel-Rehim, Mohamed

2017-09-15

Amphetamine selective molecularly imprinted sol-gel polymer tablets, MIP-tablets, for solid-phase microextraction of biofluid samples were prepared. An acetonitrile solution of deuterated amphetamine template and silane precursor, 3-(propylmethacrylate) trimethoxysilane, was soaked into the pores of polyethylene tablet substrates and polymerized by an acid-catalysed sol-gel process. Application of the resultant MIP-tablets to extract amphetamine from human urine samples followed by LC-MS/MS analysis was investigated. The extraction protocol was optimised with respect to pH of sample, addition of sodium chloride, extraction time, desorption solvent and desorption time. The final analysis method determined amphetamine in human urine with a limit of detection (LOD) of 1.0ng/mL and a lower limit of quantification (LLOQ) of 5ng/mL. Validation demonstrated accuracy of the method was 91.0-104.0% and inter-assay precision was 4.8-8.5% (RSD). Extraction recovery was 80%. The MIP-tablets could be re-used and the same tablet could be employed for more than twenty extractions. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of acetamiprid, imidacloprid, and spirotetramat and their relevant metabolites in pistachio using modified QuEChERS combined with liquid chromatography-tandem mass spectrometry.

PubMed

Faraji, Mohammad; Noorbakhsh, Roya; Shafieyan, Hooshang; Ramezani, Mohammadkazem

2018-02-01

A QuEChERS based methodology was developed for the simultaneous identification and quantification of acetamiprid, imidacloprid, and spirotetramat and their relevant metabolites in pistachio by liquid chromatography-tandem mass spectrometry for the first time. First, sample extraction was done with MeCN:citrate buffer:NaHCO 3 followed by phase separation with the addition of MgSO 4 :NaCl. The supernatant was then cleaned by a primary-secondary amine (PSA), GCB, and MgSO 4 . The proposed method provides a linearity in the range of 5-200µgL -1 , and the linear regression coefficients were higher than 0.99. LOD and LOQ were obtained to be 2 and 5µgkg -1 for the studied insecticides, respectively, with the exception of imidacloprid-olefin (5 and 10µgkg -1 ). Acceptable recoveries (91-110%) were obtained for all the analytes with good intra- and inter-precisions (0.4≥RSD ≤11.0). The method was then used for the pistachio samples collected from a field trial to estimate the maximum residue limits (MRLs) in next step. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessing the detectability of antioxidants in two-dimensional high-performance liquid chromatography.

PubMed

Bassanese, Danielle N; Conlan, Xavier A; Barnett, Neil W; Stevenson, Paul G

2015-05-01

This paper explores the analytical figures of merit of two-dimensional high-performance liquid chromatography for the separation of antioxidant standards. The cumulative two-dimensional high-performance liquid chromatography peak area was calculated for 11 antioxidants by two different methods--the areas reported by the control software and by fitting the data with a Gaussian model; these methods were evaluated for precision and sensitivity. Both methods demonstrated excellent precision in regards to retention time in the second dimension (%RSD below 1.16%) and cumulative second dimension peak area (%RSD below 3.73% from the instrument software and 5.87% for the Gaussian method). Combining areas reported by the high-performance liquid chromatographic control software displayed superior limits of detection, in the order of 1 × 10(-6) M, almost an order of magnitude lower than the Gaussian method for some analytes. The introduction of the countergradient eliminated the strong solvent mismatch between dimensions, leading to a much improved peak shape and better detection limits for quantification. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spark ablation-inductively coupled plasma spectrometry for analysis of geologic materials

USGS Publications Warehouse

Golightly, D.W.; Montaser, A.; Smith, B.L.; Dorrzapf, A.F.

1989-01-01

Spark ablation-inductively coupled plasma (SA-ICP) spectrometry is applied to the measurement of hafnium-zirconium ratios in zircons and to the determination of cerium, cobalt, iron, lead, nickel and phosphorus in ferromanganese nodules. Six operating parameters used for the high-voltage spark and argon-ICP combination are established by sequential simplex optimization of both signal-to-background ratio and signal-to-noise ratio. The time-dependences of the atomic emission signals of analytes and matrix elements ablated from a finely pulverized sample embedded in a pressed disk of copper demonstrate selective sampling by the spark. Concentration ratios of hafnium to zirconium in zircons are measured with a precision of 4% (relative standard deviation, RSD). For ferromanganese nodules, spectral measurements based on intensity ratios of analyte line to the Mn(II) 257.610 nm line provide precisions of analysis in the range from 7 to 14% RSD. The accuracy of analysis depends on use of standard additions of the reference material USGS Nod P-1, and an independent measurement of the Mn concentration. ?? 1989.

[Development and validation of an HPLC method for the quantification of vitamin A in human milk. Its application to a rural population in Argentina].

PubMed

López, Laura B; Baroni, Andrea V; Rodríguez, Viviana G; Greco, Carola B; de Costa, Sara Macías; de Ferrer, Patricia Ronayne; Rodríguez de Pece, Silvia

2005-06-01

A methodology for the quantification of vitamin A in human milk was developed and validated. Vitamin A levels were assessed in 223 samples corresponding to the 5th, 6th and 7th postpartum months, obtained in the province of Santiago del Estero, Argentina. The samples (500 microL) were saponified with potassium hydroxide/ethanol, extracted with hexane, evaporated to dryness and reconstituted with methanol. A column RP-C18, a mobile phase methanol/water (91:9 v/v) and a fluorescence detector (lambda excitation 330 nm and lambda emition 470 nm) were used for the separation and quantification of vitamin A. The analytical parameters of linearity (r2: 0.9995), detection (0.010 microg/mL) and quantification (0.025 microg/mL) limits, precision of the method (relative standard deviation, RSD = 9.0% within a day and RSD = 8.9% among days) and accuracy (recovery = 83.8%) demonstrate that the developed method allows the quantification of vitamin A in an efficient way. The mean values + standard deviation (SD) obtained for the analyzed samples were 0.60 +/- 0.32; 0.65 +/- 0.33 and 0.61 +/- 0.26 microg/ mL for the 5th, 6th and 7th postpartum months, respectively. There were no significant differences among the three months studied and the values found were similar to those in the literature. Considering the whole population under study, 19.3% showed vitamin A levels less than 0.40 microg/mL, which represents a risk to the children in this group since at least 0.50 microg/mL are necessary to meet the infant daily needs.

New Stability-Indicating RP-HPLC Method for Determination of Diclofenac Potassium and Metaxalone from their Combined Dosage Form

PubMed Central

Panda, Sagar Suman; Patanaik, Debasis; Ravi Kumar, Bera V. V.

2012-01-01

A simple, precise and accurate isocratic RP-HPLC stability-indicating assay method has been developed to determine diclofenac potassium and metaxalone in their combined dosage forms. Isocratic separation was achieved on a Hibar-C18, Lichrosphere-100® (250 mm × 4.6 mm i.d., particle size 5 μm) column at room temperature in isocratic mode, the mobile phase consists of methanol: water (80:20, v/v) at a flow rate of 1.0 ml/min, the injection volume was 20 μl and UV detection was carried out at 280nm. The drug was subjected to acid and alkali hydrolysis, oxidation, photolysis and heat as stress conditions. The method was validated for specificity, linearity, precision, accuracy, robustness and system suitability. The method was linear in the drug concentration range of 2.5–30 μg/ml and 20–240 μg/ml for diclofenac potassium and metaxalone, respectively. The precision (RSD) of six samples was 0.83 and 0.93% for repeatability, and the intermediate precision (RSD) among six-sample preparation was 1.63 and 0.49% for diclofenac potassium and metaxalone, respectively. The mean recoveries were between 100.99–102.58% and 99.97–100.01% for diclofenac potassium and metaxalone, respectively. The proposed method can be used successfully for routine analysis of the drug in bulk and combined pharmaceutical dosage forms. PMID:22396909

Sensitive determination of melamine in milk and powdered infant formula samples by high-performance liquid chromatography using dabsyl chloride derivatization followed by dispersive liquid-liquid microextraction.

PubMed

Faraji, M; Adeli, M

2017-04-15

A new and sensitive pre-column derivatization with dabsyl chloride followed by dispersive liquid-liquid microextraction was developed for the analysis of melamine (MEL) in raw milk and powdered infant formula samples by high performance liquid chromatography (HPLC) with visible detection. Derivatization with dabsyl chloride leads to improving sensitivity and hydrophobicity of MEL. Under optimum conditions of derivatization and microextraction steps, the method yielded a linear calibration curve ranging from 1.0 to 500μgL -1 with a determination coefficient (R 2 ) of 0.9995. Limit of detection and limit of quantification were 0.1 and 0.3μgL -1 , respectively. The relative standard deviation (RSD%) for intra-day (repeatability) and inter-day (reproducibility) at 25 and 100μgL -1 levels of MEL was less than 7.0% (n=6). Finally, the proposed method was successfully applied for the preconcentration and determination of MEL in different raw milk and powdered infant formula, and satisfactory results were obtained (relative recovery ⩾94%). Copyright © 2016 Elsevier Ltd. All rights reserved.

Quality evaluation of Yin Chen Hao Tang extract based on fingerprint chromatogram and simultaneous determination of five bioactive constituents.

PubMed

Wang, Xijun; Lv, Haitao; Sun, Hui; Jiang, Xingang; Wu, Zeming; Sun, Wenjun; Wang, Ping; Liu, Lian; Bi, Kaishun

2008-01-01

A completely validated method based on HPLC coupled with photodiode array detector (HPLC-UV) was described for evaluating and controlling quality of Yin Chen Hao Tang extract (YCHTE). First, HPLC-UV fingerprint chromatogram of YCHTE was established for preliminarily elucidating amount and chromatographic trajectory of chemical constituents in YCHTE. Second, for the first time, five mainly bioactive constituents in YCHTE were simultaneously determined based on fingerprint chromatogram for furthermore controlling the quality of YCHTE quantitatively. The developed method was applied to analyze 12 batches of YCHTE samples which consisted of herbal drugs from different places of production, showed acceptable linearity, intraday (RSD <5%), interday precision (RSD <4.80%), and accuracy (RSD <2.80%). As a result, fingerprint chromatogram determined 15 representative general fingerprint peaks, and the fingerprint chromatogram resemblances are all better than 0.9996. The contents of five analytes in different batches of YCHTE samples do not indicate significant difference. So, it is concluded that the developed HPLC-UV method is a more fully validated and complete method for evaluating and controlling the quality of YCHTE.

Validated UPLC-MS/MS method for quantification of seven compounds in rat plasma and tissues: Application to pharmacokinetic and tissue distribution studies in rats after oral administration of extract of Eclipta prostrata L.

PubMed

Du, Guangyan; Fu, Lingling; Jia, Jun; Pang, Xu; Yu, Haiyang; Zhang, Youcai; Fan, Guanwei; Gao, Xiumei; Han, Lifeng

2018-06-01

A rapid, sensitive and specific ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) method was developed to investigate the pharmacokinetics and tissue distribution of Eclipta prostrata extract. Rats were orally administrated the 70% ethanol extract of E. prostrata, and their plasma as well as various organs were collected. The concentrations of seven main compounds, ecliptasaponin IV, ecliptasaponin A, apigenin, 3'-hydroxybiochanin A, luteolin, luteolin-7-O-glucoside and wedelolactone, were quantified by UPLC-MS/MS through multiple reactions monitoring method. The precisions (RSD) of the analytes were all <15.00%. The extraction recoveries ranged from 74.65 to 107.45% with RSD ≤ 15.36%. The matrix effects ranged from 78.00 to 118.06% with RSD ≤ 15.04%. To conclude, the present pharmacokinetic and tissue distribution studies provided useful information for the clinical usage of Eclipta prostrata L. Copyright © 2018 John Wiley & Sons, Ltd.

DETERMINATION OF AZOXYSTROBIN AND DIFENOCONAZOLE IN PESTICIDE PRODUCTS.

PubMed

Lazić, S; Šunjka, D

2015-01-01

In this study a high performance liquid chromatographic (HPLC-DAD) procedure has been developed for the simultaneous determination of azoxystrobin and difenoconazole in suspension concentrate pesticide formulations, with the aim of the product quality control. Azoxystrobin, strobilurin fungicide and difenoconazole (cis,trans-3-chloro-4-[4-methyl-2-(1H-1,2,4-triazol-1-ylmethyl)-1,3-dioxolan-2-yl]phenyl 4-chlorophenyl ether), triazole fungicide, are used for the protection of plants from wide spectrum of fungal diseases. For the analysis LC system an Agilent Technologies 1100 Series was used. Good separation was achieved on a Zorbax SB-C18 column (5 μm, 250 mm x 3 mm internal diameter) using a mobile phase consisting of acetonitrile/ultrapure water (90:10, v/v), at a flow rate of 0.9 ml/minute and UV detection at 218 nm. Column temperature was 25 degrees C, injected volume was 1 μl. Retention times for azoxystrobin and difenoconazole were 2.504 min and 1.963 min, respectively. This method is validated according to the requirements for new methods, which include linearity, precision, accuracy and selectivity. The method demonstrates good linearity with r2 > 0.997. The repeatability of the method, expressed as relative standard deviation (RSD, %), was found to be 1.9% for azoxystrobin and 0.5% for difenoconazole. The precision of the method was also considered to be acceptable as the experimental repeatability relative standard deviation (RSD) was lower than the RSD calculated using the Horwitz equation of 1.7% and 1.4% for azoxystrobin and difenoconazole, respectively. The accuracy of the proposed method was determined from recovery experiments through standard addition procedure. The average recoveries of the three fortification levels were 101.9% for azoxystrobin and 103.2% for difenoconazole with RSDs of 1.1% and 1.2%. The method described in this paper is simple, precise, accurate and selective and represents a new and reliable way of simultaneous determination of azoxystrobin and difenoconazole in formulated products.

Determination and validation of a simple high-performance liquid chromatographic method for simultaneous assay of iprodione and vinclozolin in human urine.

PubMed

Carlucci, Giuseppe; Pasquale, Dorina Di; Ruggieri, Fabrizio; Mazzeo, Pietro

2005-12-15

A method based on solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) was developed for the simultaneous determination of 3-(3,5-diclorophenyl)-5-ethenyl-5-methyl-2,4-oxazolidinedione (vinclozolin) and 3-(3,5-diclorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecarboxamide (iprodione) in human urine. Urine samples containing vinclozolin and iprodione were collected by solid phase extraction using C(18) cartridges. The chromatographic separation was achieved on a Spherisorb ODS2 (250 mm x 4.6 mm, 5 microm) column with an isocratic mobile phase of acetonitrile-water (60:40, v/v). Detection was UV absorbance at 220 nm. The calibration graphs were linear from 30 to 1000 ng/mL for the two fungicides. Intra- and inter-day R.S.D. did not exceed 2.9%. The quantitation limit was 50 ng/mL for vinclozolin and 30 ng/mL for iprodione, respectively.

Determination of urinary 6-mercaptopurine and three of its metabolites by HPLC-UV coupled with the iodine-azide reaction.

PubMed

Zakrzewski, Robert; Borowczyk, Kamila; Łuczak, Adam; Młynarski, Wojciech; Trelińska, Joanna

2013-04-01

The presented method is able to determine 6-mercaptopurine (6-MP), 6-thioguanine, 6-mercaptopurine riboside and 6-thioguanine riboside in urine, and is thereby dedicated to control of thiopurine therapy of children with acute lymphoblastic leukemia. Good separation of the mentioned compounds was achieved on a C18 stationary phase with a sodium azide and sodium heptane sulfonate solution, acetonitrile and water at ratio of 50:1:49 (v/v/v). Coefficient of regression is >0.99 for all linearity ranges. LOD and LOQ are 0.3, 0.4, 0.3, 0.8 and 0.4, 0.6, 0.5 and 0.9 nmol/ml of urine for 6-MP, 6-thioguanine, 6-mercaptopurine riboside and 6-thioguanine riboside, respectively. Intra- and inter-day recovery and RSD are close to 100% and less than 10%, respectively, for all investigated thiopurines. The elaborated method was successfully applied for detection and quantitation of 6-MP and its selected metabolites in patients' urine samples.

Synthesis of magnetic molecularly imprinted polymers for the selective separation and determination of metronidazole in cosmetic samples.

PubMed

Liu, Min; Li, Xiao-Yan; Li, Jun-Jie; Su, Xiao-Meng; Wu, Zong-Yuan; Li, Peng-Fei; Lei, Fu-Hou; Tan, Xue-Cai; Shi, Zhan-Wang

2015-05-01

In this study, novel magnetic molecularly imprinted polymers (MMIPs) were developed as a sorbent for solid-phase extraction (SPE) and used for the selective separation of metronidazole (MNZ) in cosmetics; MNZ was detected by high-performance liquid chromatography (HPLC). First, magnetic Fe3O4 nanoparticles (NPs) were prepared by the co-precipitation of Fe(2+)and Fe(3+) ions in an ammonia solution; then oleic acid (OA) was modified onto the surface of Fe3O4NPs. Finally, the MMIP was prepared by aqueous suspension polymerization, involving the copolymerization of Fe3O4NPs@OA with MNZ as the template molecule, methacrylic acid (MAA) as the functional monomer, ethylene glycol maleic rosinate acrylate (EGMRA) as the cross-linking agent, and 2,2-azobisisobutyronitrile (AIBN) as the initiator. The MMIP materials showed high selective adsorption capacity and fast binding kinetics for MNZ; the maximum adsorption amount of the MMIP to MNZ was 46.7 mg/g. The assay showed a linear range from 0.1 to 20.0 μg/mL for MNZ with the correlation coefficient 0.999. The relative standard deviations (RSD) of intra- and inter-day ranging from 0.71 to 2.45% and from 1.06 to 5.20% were obtained. The MMIP can be applied to the enrichment and determination of MNZ in cosmetic products with the recoveries of spiked toner, powder, and cream cosmetic samples ranging from 90.6 to 104.2, 84.1 to 91.4, and 90.3 to 100.4%, respectively, and the RSD was <3.54%.

Selective molecularly imprinted polymer combined with restricted access material for in-tube SPME/UHPLC-MS/MS of parabens in breast milk samples.

PubMed

Souza, Israel D; Melo, Lidervan P; Jardim, Isabel C S F; Monteiro, Juliana C S; Nakano, Ana Marcia S; Queiroz, Maria Eugênia C

2016-08-17

A new molecularly imprinted polymer modified with restricted access material (a hydrophilic external layer), (MIP-RAM) was synthesized via polymerization in situ in an open fused silica capillary. This stationary phase was used as sorbent for in-tube solid phase microextraction (in-tube SPME) to determine parabens in breast milk samples by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Scanning electron micrographs (SEM) illustrate MIP surface modification after glycerol dimethacrylate (hydrophilic monomer) incorporation. The interaction between parabens and MIP-RAM was investigated by Fourier-transform infrared (FTIR) spectroscopy. The Scatchard plot for MIP-RAM presented two linear parts with different slopes, illustrating binding sites with high- and low-affinity. Endogenous compounds exclusion from the MIP-RAM capillary was demonstrated by in-tube SPME/LC-UV assays carried out with blank milk samples. The in-tube SPME/UHPLC-MS/MS method presented linear range from 10 ng mL(-1) (LLOQ) to 400 ng mL(-1) with coefficients of determination higher than 0.99, inter-assay precision with coefficient of variation (CV) values ranging from 2 to 15%, and inter-assay accuracy with relative standard deviation (RSD) values ranging from -1% to 19%. Analytical validation parameters attested that in-tube SPME/UHPLC-MS/MS is an appropriate method to determine parabens in human milk samples to assess human exposure to these compounds. Analysis of breast milk samples from lactating women demonstrated that the proposed method is effective. Copyright © 2016 Elsevier B.V. All rights reserved.

Spectral relative standard deviation: a practical benchmark in metabolomics.

PubMed

Parsons, Helen M; Ekman, Drew R; Collette, Timothy W; Viant, Mark R

2009-03-01

Metabolomics datasets, by definition, comprise of measurements of large numbers of metabolites. Both technical (analytical) and biological factors will induce variation within these measurements that is not consistent across all metabolites. Consequently, criteria are required to assess the reproducibility of metabolomics datasets that are derived from all the detected metabolites. Here we calculate spectrum-wide relative standard deviations (RSDs; also termed coefficient of variation, CV) for ten metabolomics datasets, spanning a variety of sample types from mammals, fish, invertebrates and a cell line, and display them succinctly as boxplots. We demonstrate multiple applications of spectral RSDs for characterising technical as well as inter-individual biological variation: for optimising metabolite extractions, comparing analytical techniques, investigating matrix effects, and comparing biofluids and tissue extracts from single and multiple species for optimising experimental design. Technical variation within metabolomics datasets, recorded using one- and two-dimensional NMR and mass spectrometry, ranges from 1.6 to 20.6% (reported as the median spectral RSD). Inter-individual biological variation is typically larger, ranging from as low as 7.2% for tissue extracts from laboratory-housed rats to 58.4% for fish plasma. In addition, for some of the datasets we confirm that the spectral RSD values are largely invariant across different spectral processing methods, such as baseline correction, normalisation and binning resolution. In conclusion, we propose spectral RSDs and their median values contained herein as practical benchmarks for metabolomics studies.

Rapid planar chromatographic analysis of 25 water-soluble dyes used as food additives.

PubMed

Morlock, Gertrud E; Oellig, Claudia

2009-01-01

A rapid planar chromatographic method for identification and quantification of 25 water-soluble dyes in food was developed. In a horizontal developing chamber, the chromatographic separation on silica gel 60F254 high-performance thin-layer chromatography plates took 12 min for 40 runs in parallel, using 8 mL ethyl acetate-methanol-water-acetic acid (65 + 23 + 11 + 1, v/v/v/v) mobile phase up to a migration distance of 50 mm. However, the total analysis time, inclusive of application and evaluation, took 60 min for 40 runs. Thus, the overall time/run can be calculated as 1.5 min with a solvent consumption of 200 microL. A sample throughput of 1000 runs/8 h day can be reached by switching between the working stations (application, development, and evaluation) in a 20 min interval, which triples the analysis throughput. Densitometry was performed by absorption measurement using the multiwavelength scan mode in the UV and visible ranges. Repeatabilities [relative standard deviation (RSD), 4 determinations] at the first or second calibration level showed precisions of mostly < or = 2.7%, ranging between 0.2 and 5.2%. Correlation coefficient values (R > or = 0.9987) and RSD values (< or = 4.2%) of the calibration curves were highly satisfactory using classical quantification. However, digital evaluation of the plate image was also used for quantification, which resulted in RSD values of the calibration curves of mostly < or = 3.0%, except for two < or = 6.0%. The method was applied for the analysis of some energy drinks and bakery ink formulations, directly applied after dilution. By recording of absorbance spectra in the visible range, the identities of the dyes found in the samples were ascertained by comparison with the respective standard bands (correlation coefficients > or = 0.9996). If necessary for confirmation, online mass spectra were recorded within a minute.

Pulmonary vein isolation combined with spironolactone or renal sympathetic denervation in patients with chronic kidney disease, uncontrolled hypertension, paroxysmal atrial fibrillation, and a pacemaker.

PubMed

Kiuchi, Márcio Galindo; Chen, Shaojie; Hoye, Neil Alexander; Pürerfellner, Helmut

2018-01-01

Atrial fibrillation (AF) commonly occurs in chronic kidney disease (CKD), occasioning adverse outcomes. Merging pulmonary vein isolation (PVI) and renal sympathetic denervation (RSD) may decrease the recurrence of AF in subjects with CKD and uncontrolled hypertension. We considered that RSD could reduce the recurrence of AF in patients with CKD by modulating sympathetic hyperactivity. We aimed to evaluate the impact of RSD or spironolactone 50 mg/day associated with PVI in reducing systolic blood pressure (BP), AF recurrence, and AF burden in patients with a history of paroxysmal AF and mild CKD. This was a single-center, prospective, longitudinal, randomized, double-blind study. The individuals were randomly divided into two groups (PVI + spironolactone, n = 36, and PVI + RSD, n = 33). All of them were followed for exactly 1 year to assess maintenance of sinus rhythm and to monitor the other variables. Ambulatory BP measurements were reduced in both groups and at the 12th month also differed between groups. Significantly more patients in the PVI + RSD (61%) than in the PVI + spironolactone group (36%) were AF-free at the 12th month of follow-up, P = 0.0242. Toward the end of the study, the mean AF burden was lower in the PVI + RSD group as compared to PVI + spironolactone group, at the 9th month: ∆ = - 10% (P < 0.0001), and at the 12th month: ∆ = - 12% (P < 0.0001), respectively. PVI + RSD is safe and appears to be superior to PVI + spironolactone in BP reduction, augmentation of AF event-free rate, reduction of AF burden, and improvement of renal function.

The effect of photometric redshift uncertainties on galaxy clustering and baryonic acoustic oscillations

NASA Astrophysics Data System (ADS)

Chaves-Montero, Jonás; Angulo, Raúl E.; Hernández-Monteagudo, Carlos

2018-04-01

In the upcoming era of high-precision galaxy surveys, it becomes necessary to understand the impact of redshift uncertainties on cosmological observables. In this paper we explore the effect of sub-percent photometric redshift errors (photo-z errors) on galaxy clustering and baryonic acoustic oscillations (BAO). Using analytic expressions and results from 1 000 N-body simulations, we show how photo-z errors modify the amplitude of moments of the 2D power spectrum, their variances, the amplitude of BAO, and the cosmological information in them. We find that: a) photo-z errors suppress the clustering on small scales, increasing the relative importance of shot noise, and thus reducing the interval of scales available for BAO analyses; b) photo-z errors decrease the smearing of BAO due to non-linear redshift-space distortions (RSD) by giving less weight to line-of-sight modes; and c) photo-z errors (and small-scale RSD) induce a scale dependence on the information encoded in the BAO scale, and that reduces the constraining power on the Hubble parameter. Using these findings, we propose a template that extracts unbiased cosmological information from samples with photo-z errors with respect to cases without them. Finally, we provide analytic expressions to forecast the precision in measuring the BAO scale, showing that spectro-photometric surveys will measure the expansion history of the Universe with a precision competitive to that of spectroscopic surveys.

Determination of Antimycin-A in water by liquid chromatographic/mass spectrometry: single-laboratory validation

USGS Publications Warehouse

Bernardy, Jeffry A.; Hubert, Terrance D.; Ogorek, Jacob M.; Schmidt, Larry J.

2013-01-01

An LC/MS method was developed and validated for the quantitative determination and confirmation of antimycin-A (ANT-A) in water from lakes or streams. Three different water sample volumes (25, 50, and 250 mL) were evaluated. ANT-A was stabilized in the field by immediately extracting it from water into anhydrous acetone using SPE. The stabilized concentrated samples were then transported to a laboratory and analyzed by LC/MS using negative electrospray ionization. The method was determined to have adequate accuracy (78 to 113% recovery), precision (0.77 to 7.5% RSD with samples ≥500 ng/L and 4.8 to 17% RSD with samples ≤100 ng/L), linearity, and robustness over an LOQ range from 8 to 51 600 ng/L.

Determination of antimycin-A in water by liquid chromatographic/mass spectrometry: single-laboratory validation.

PubMed

Bernardy, Jeffry A; Hubert, Terrance D; Ogorek, Jacob M; Schmidt, Larry J

2013-01-01

An LC/MS method was developed and validated for the quantitative determination and confirmation of antimycin-A (ANT-A) in water from lakes or streams. Three different water sample volumes (25, 50, and 250 mL) were evaluated. ANT-A was stabilized in the field by immediately extracting it from water into anhydrous acetone using SPE. The stabilized concentrated samples were then transported to a laboratory and analyzed by LC/MS using negative electrospray ionization. The method was determined to have adequate accuracy (78 to 113% recovery), precision (0.77 to 7.5% RSD with samples > or = 500 ng/L and 4.8 to 17% RSD with samples < or = 100 ng/L), linearity, and robustness over an LOQ range from 8 to 51 600 ng/L.

A rapid method for the simultaneous determination of 25 anti-hypertensive compounds in dietary supplements using ultra-high-pressure liquid chromatography.

PubMed

Heo, Seok; Yoo, Geum Joo; Choi, Ji Yeon; Park, Hyoung Joon; Park, Sung-Kwan; Baek, Sun Young

2016-11-01

A novel, stable, simple and specific ultra-performance liquid chromatography method with ultraviolet detection (205 nm) for the simultaneous analysis of 25 anti-hypertensive substances was developed. The method was validated according to the International Conference of Harmonisation guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and stability. From the ultra-performance liquid chromatography results, we identified the LOD and LOQ of solid samples to be 0.20-1.00 and 0.60-3.00 μg ml -1 , respectively, while those of liquid samples were 0.30-1.20 and 0.90-3.60 μg ml -1 , respectively. The linearity exceeded 0.9999, and the intra- and inter-day precisions were 0.15-6.48% and 0.28-8.67%, respectively. The intra- and inter-day accuracies were 82.25-111.42% and 80.70-115.64%, respectively, and the stability was lower than 12.9% (relative standard deviation). This method was applied to the monitoring of 97 commercially available dietary supplements obtained in Korea, such as pills, soft capsules, hard capsules, liquids, powders and tablets. The proposed method is accurate, precise and of high quality, and can be used for the routine, reproducible analysis and control of 25 anti-hypertensive substances in various dietary supplements. The work presented herein may help to prevent incidents related to food adulteration and restrict the illegal food market.

Determination of (2)H-enrichment of rat brain interstitial fluid and rat plasma by headspace-gas-chromatography - quadrupole-mass-spectrometry.

PubMed

Eberl, Anita; Altendorfer-Kroath, Thomas; Kollmann, Denise; Birngruber, Thomas; Sinner, Frank; Raml, Reingard; Magnes, Christoph

2016-09-15

(2)H2O as nonradioactive, stable marker substance is commonly used in preclinical and clinical studies and the precise determination of (2)H2O concentration in biological samples is crucial. However, aside from isotope ratio mass spectrometry (IRMS), only a very limited number of methods to accurately measure the (2)H2O concentration in biological samples are routinely established until now. In this study, we present a straightforward method to accurately measure (2)H-enrichment of rat brain interstitial fluid (ISF) and rat plasma to determine the relative recovery of a cerebral open flow microperfusion (cOFM) probe, using headspace-gas-chromatography - quadrupole-mass-spectrometry. This method is based on basic-catalyzed hydrogen/deuterium exchange in acetone and detects the (2)H-labelled acetone directly by the headspace GC-MS. Small sample volumes and limited number of preparation steps make this method highly competitive. It has been fully validated. (2)H enriched to 8800 ppm in plasma showed an accuracy of 98.9% and %Relative Standard Deviation (RSD) of 3.1 with n = 18 over three days and with two operators. Similar performance was obtained for cerebral ISF enriched to 1100 ppm (accuracy: 96.5%, %RSD: 3.1). With this highly reproducible method we demonstrated the successful employment of (2)H2O as performance marker for a cOFM probe. Copyright © 2016. Published by Elsevier Inc.

[Application of asymmetrical flow field-flow fractionation for size characterization of low density lipoprotein in egg yolk plasma].

PubMed

Zhang, Wenhui; Cai, Chunxue; Wang, Jing; Mao, Zhen; Li, Yueqiu; Ding, Liang; Shen, Shigang; Dou, Haiyang

2017-08-08

Home-made asymmetrical flow field-flow fractionation (AF4) system, online coupled with ultraviolet/visible (UV/Vis) detector was employed for the separation and size characterization of low density lipoprotein (LDL) in egg yolk plasma. At close to natural condition of egg yolk, the effects of cross flow rate, sample loading, and type of membrane on the size distribution of LDL were investigated. Under the optimal operation conditions, AF4-UV/Vis provides the size distribution of LDL. Moreover, the precision of AF4-UV/Vis method proposed in this work for the analysis of LDL in egg yolk plasma was evaluated. The intra-day precisions were 1.3% and 1.9% ( n =7) and the inter-day precisions were 2.4% and 2.3% ( n =7) for the elution peak height and elution peak area of LDL, respectively. Results reveal that AF4-UV/Vis is a useful tool for the separation and size characterization of LDL in egg yolk plasma.

Development of a candidate reference measurement procedure for the analysis of cortisol in human serum samples by isotope dilution-gas chromatography-mass spectrometry.

PubMed

Kawaguchi, Migaku; Takatsu, Akiko

2009-08-01

A candidate reference measurement procedure involving isotope dilution coupled with gas chromatography-mass spectrometry (GC-MS) has been developed and critically evaluated. An isotopically labeled internal standard, cortisol-d(2), was added to a serum sample. After equilibration, solid-phase extractions (SPE) for sample preparation and derivatization with heptafluorobutyric anhydride (HFBA) were performed for GC-MS analysis. The limit of detection (LOD) and the limit of quantification (LOQ) were 5 and 20 ng g(-1), respectively. The recovery of the added cortisol ranged from 99.8 to 101.0%. Excellent precision was obtained with a within-day variation (RSD) of 0.7% for GC-MS analysis. The accuracy of the measurement was evaluated by comparing of results of this reference measurement procedure on lyophilized human serum reference materials for cortisol (European Reference Materials (ERM)-DA 192) as Certified Reference Materials (CRMs). The results of this method for total cortisol agreed with the certified values within some uncertainty. This method, which demonstrates simply, easy, good accuracy, high precision, and is free from interferences from structural analogues, qualifies as a reference measurement procedure.

Determination of phenolic compounds derived from hydrolysable tannins in biological matrices by RP-HPLC.

PubMed

Díez, María Teresa; García del Moral, Pilar; Resines, José Antonio; Arín, María Jesús

2008-08-01

An RP-HPLC method for the determination of four phenolic compounds: gallic acid (GA), pyrogallol (PY), resorcinol (RE) and ellagic acid (EA), derived from hydrolysable tannins is reported. Separation was achieved on a SunFire C18 (250 x 4.6 mm id, 5 microm) column at 40 degrees C with gradient elution. UV detection at 280 nm was applied. The developed method was validated in terms of linearity, accuracy and precision. Satisfactory repeatability and between day precision were noticed with RSD values lower than 3%. Recoveries from different biological samples ranged from 91.50 to 105.25%. The LODs were estimated as 1.70 mg/L for PY, 1.68 mg/L for GA, 1.52 mg/L for RE and 0.98 mg/L for EA with a 20 microL injection volume. The method was applied for the determination of these compounds in oak leaves and in ruminal fluid and urine samples taken from beef cattle fed with oak leaves. The proposed method could be used in ruminant nutrition studies to verify the effect that a diet rich in tannins have on ruminal fermentation and to determine the toxicity of these compounds.

Inclusion of 1-naphthylacetic acid and 2-(1-naphthyl)acetamide into three typical multiresidue methods for LC/MS/MS analysis of tomatoes and zucchini.

PubMed

Lozano, Ana; Pérez-Parada, Andrés; Heinzen, Horacio; Fernández-Alba, Amadeo R

2012-01-01

In spite of high plant growth regulator application rates, little has been reported in the literature on determination of their residues in fruits and vegetables. This would be useful in monitoring good manufacturing practices and overall safety through the enforcement of maximum residue levels (MRLs). The present work describes method validation for the determination of 1-naphthylacetic acid (NAA) and 2(1-naphthyl)acetamide (NAAm) in tomato and zucchini using the mini-Luke, ethyl acetate (EtOAc) and acetate-buffered quick, easy, cheap, effective, rugged, and safe (QuEChERS) methods. Samples were spiked at two different levels: 50 and 100 pg/kg for NAA and 20 and 100 pg/kg for NAAm. These compounds were analyzed within the same chromatographic run with LC coupled to triple quadrupole MS (LC/(QqQ)MS/MS) in positive and negative electrospray ionization [ESI(+) and ESI(-)] modes for NAAm and NAA, respectively. For analyte confirmation, LC/ESI(-)QTOF-MS was also investigated given that NAA has only one multiple reaction monitoring transition (185.1-*140.9 m/z). These three common methods were used to determine linearity, recoveries, precision (RSD), matrix effects, repeatability, and reproducibility (n = 5) for the selected matrixes. In terms of the Directorate-General for Health and Consumers (DG-SANCO) guidelines, only insignificant differences were found for the multiresidue methods tested, regardless of the commodity. Matrix-matched calibration was used, and LODs were below 10.1 pg/kg for NAA and 6.0 pg/kg for NAAm, which were lower than the MRLs established in current European Union legislation for these compounds. Obtained recoveries for NAA ranged from 87 to 107% with RSD values below 10% for mini-Luke, 83 to 107% with RSD <11% for EtOAc, and 76 to 85% with RSD <7% for QuEChERS. NAAm recoveries ranged from 74 to 102% with RSD 5 15% for mini-Luke, 76 to 97% with RSD <4% for EtOAc, and 76 to 93% with RSD < 5% for QuEChERS. The linearity of the response over two orders of magnitude was demonstrated (r2 > 0.996) for all methods used. Good repeatability and reproducibility in terms of RSD were obtained (11.3-17.8%) for these analytical methods. The results were acceptable within the studied ranges for both analytes in all methods. As these multiresidue methods are used at the present time in many laboratories, this survey indicates that these analytes should be included in their monitoring scope.

Determination of soluble immunoglobulin G in bovine colostrum products by Protein G affinity chromatography-turbidity correction and method validation.

PubMed

Holland, Patrick T; Cargill, Anne; Selwood, Andrew I; Arnold, Kate; Krammer, Jacqueline L; Pearce, Kevin N

2011-05-25

Immunoglobulin-containing food products and nutraceuticals such as bovine colostrum are of interest to consumers as they may provide health benefits. Commercial scale colostrum products are valued for their immunoglobulin G (IgG) content and therefore require accurate analysis. One of the most commonly used methods for determining total soluble IgG in colostrum products is based on affinity chromatography using a Protein G column and UV detection. This paper documents improvements to the accuracy of the Protein G analysis of IgG in colostrum products, especially those containing aggregated forms of IgG. Capillary electrophoresis-sodium dodecyl sulfate (CE-SDS) analysis confirmed that aggregated IgG measured by Protein G does not contain significant amounts of casein or other milk proteins. Size exclusion chromatography identified the content of soluble IgG as mainly monomeric IgG and aggregated material MW > 450 kDa with small amounts of dimer and trimer. The turbidity of the eluting IgG, mainly associated with aggregated IgG, had a significant effect on the quantitative results. Practical techniques were developed to correct affinity LC data for turbidity on an accurate, consistent, and efficient basis. The method was validated in two laboratories using a variety of colostrum powders. Precision for IgG was 2-3% (RSD(r)) and 3-12% (RSD(R)). Recovery was 100.2 ± 2.4% (mean ± RSD, n = 10). Greater amounts of aggregated IgG were solubilized by a higher solution:sample ratio and extended times of mixing or sonication, especially for freeze-dried material. It is concluded that the method without acid precipitation and with turbidity correction provides accurate, precise, and robust data for total soluble IgG and is suitable for product specification and quality control of colostrum products.

Rapid determination of fumonisins in corn-based products by liquid chromatography/tandem mass spectrometry.

PubMed

Li, Wei; Herrman, Timothy J; Dai, Susie Y

2010-01-01

A simple, fast, and robust method was developed for the determination of fumonisin B1 (FB1), fumonisin B2 (FB2), and fumonisin B3 (FB3) in corn-based human food and animal feed (cornmeal). The method involves a single extraction step followed by centrifugation and filtration before analysis by ultra-performance liquid chromatographylelectrospray ionization (UPLC/ESI)-MS/MS. The LC/MS/MS method developed here represents the fastest and simplest procedure (<30 min) among both conventional HPLC methods and other LC/MS methods using SPE cleanup. The potential for high throughput analysis makes the method particularly beneficial for regulatory agencies and analytical laboratories with a high sample volume. A single-laboratory validation was conducted by testing three different spiking levels (200, 500, and 1000 ng/g for FB1 and FB2; 100, 250, and 500 ng/g for FB3) for accuracy and precision. Recoveries of FB1 ranged from 93 to 98% with RSD values of 3-8%. Recoveries of FB2 ranged from 104 to 108%, with RSD values of 2-6%. Recoveries of FB3 ranged from 94 to 108%, with RSD values of 2-5%.

LC-MS/MS method for the determination of clodronate in human plasma.

PubMed

Hasan, Mahmoud; Schumacher, Gitta; Seekamp, Anne; Taedken, Tobias; Siegmund, Werner; Oswald, Stefan

2014-11-01

Clodronate belongs to the class of bisphosphonates which are used for the treatment of bone disorders. Due to its high polarity it has a low and highly variable oral bioavailability which results in low plasma concentrations and requires sensitive bioanalytical methods to characterize its pharmacokinetics in human. Here, we describe for the first time the development and validation of a LC-MS/MS assay for the quantification of clodronate in human plasma. The bisphosphonate was isolated from the biological matrix by protein precipitation using perchloric acid (10%), and derivatized with trimethylorthoacetate prior sample clean-up with liquid-liquid extraction using methyl tert-butyl ether. The chromatography was performed using an isocratic elution with ammonium acetate 5mM (85% v/v, pH 3.8) and acetonitrile (15% v/v) as mobile phase with a flow rate of 300μl/min on a reversed-phase column (Supelco Ascentis(®), C18) temporized at 50°C. The mass spectrometric detection was done using the API4000 triple quadruple mass spectrometer monitoring the mass/charge transitions 301.0/145 for clodronate and 305.2/137.1 for the internal standard etidronate. The analytical range was set to 5-800ng/ml, allowing an evaluation of the plasma concentration-time profiles of clodronate for approximately 7-8 half-life (∼24h). The method was validated according to current FDA/EMA guidelines on bioanalytical method validation with respect to specificity, linearity, intra- and inter-day accuracy and precision, matrix effect, recovery as well as stability. The precision of the assay was 0.6-6.9% and 0.6-8.1% for the intra-day and inter-day variability, respectively. The intra-day and inter-day accuracy (error) was 0.6-8.8% and 2.2-4.5%. The recovery of the analyte was low (2-3%) but reproducible over the entire validation range and sufficient to monitor the target concentrations in human plasma. The drug was shown to be stable in plasma at room temperature for at least 3h (96.0±6%) and for at least 24h when stored in the cooled autosampler at 4°C (102.4±4.5%). Clodronate can also undergo up to three freeze-thaw cycles without impaired stability. Thus, the method was shown to possess sufficient specificity, sensitivity, accuracy, precision and stability to measure plasma concentrations of clodronate. Finally, the developed method was successfully applied to study the clodronate serum levels in a pharmacokinetic study in healthy volunteers. Copyright © 2014 Elsevier B.V. All rights reserved.

Ultra-HPLC method for quality and adulterant assessment of steviol glycosides sweeteners - Stevia rebaudiana and stevia products.

PubMed

Wang, Yan-Hong; Avula, Bharathi; Tang, Wenzhao; Wang, Mei; Elsohly, Mahmoud A; Khan, Ikhlas A

2015-01-01

Stevia products are advertised as a zero-calorie sweetener. Glucose should not be an intrinsic component of this product, but it has been identified from some of stevia products in a preliminary study. An UHPLC-UV method was developed for the quantitative determination of glucose from stevia products. After stevia products reacted with 1-phenyl-3-methyl-5-pyrazolone (PMP), PMP derivatives were analysed and glucose was found in seven out of 35 products in the range 0.3-91.5% (w/w). Two products, SPR-12 and SPR-27, showed remarkable amounts of glucose at 61.6% and 91.5%, respectively. In addition, an UHPLC-UV-evaporative light-scattering detector (ELSD) method was developed for the quantitative determination of rebaudioside A, stevioside, rebaudioside D, dulcoside A and steviolbioside from Stevia rebaudiana and related products. In a 12 min run, five steviol glycosides were baseline-separated. ELSD and ultraviolet (UV) detections showed comparable results. The LC methods were validated for linearity, repeatability, accuracy, limits of detection (LOD) and limits of quantification (LOQ). For steviol glycosides, the LODs and LOQs were found to be less than 10 and 30 μg ml(-1), respectively. The RSD for intra- and inter-day analyses was less than 2.5%, and the recovery was 90-94%. For PMP derivative of glucose, the LOD and LOQ were 0.01 and 0.05 μg ml(-1), respectively. Repeatability (RSD) was less than 2.6%; recovery was 98.6-101.7%. The methods are useful for the identification, quality assurance, and adulterant assessment of S. rebaudiana and steviol glycosides sweeteners (stevia products).

Simultaneous determination of seven taxoids in rat plasma by UPLC-MS/MS and pharmacokinetic study after oral administration of Taxus yunnanensis extracts.

PubMed

Liu, Bin; Gou, Xiaoli; Bai, Xupeng; Hou, Xiangyu; Li, Dongshun; Zhong, Guoping; Jin, Jing; Huang, Min

2015-03-25

A rapid, sensitive and reliable method has been developed and validated for the simultaneous determination of seven taxoids including 10-deacetylbaccatin III (10-DAB III), baccatin III, 5-epi-canadensene, taxinine M, 10-deacetyltaxol (10-DAT), cephalomannine and paclitaxel in rat plasma using docetaxel as the internal standard (IS). The plasma samples were pretreated by liquid-liquid extraction with methyl tert-butyl ether. The chromatographic separation was achieved on a C18 column (50 mm × 2.1 mm, 1.8 μm, Waters, USA) with a gradient elution program consisting of methanol and water (containing 0.1% formic acid) at a flow rate of 0.2 mL/min. Detection was performed under the selected reaction monitoring (SRM) scan using an electrospray ionization (ESI) in the positive ion mode. The mass transitions were as follows: m/z 567.4→444.9 for 10-DAB III, m/z 609.0→549.3 for baccatin III, m/z 617.4→496.9 for 5-epi-canadensene, m/z 709.6→649.3 for taxinine M, m/z 834.8→307.9 for 10-DAT, m/z 854.5→285.4 for cephalomannine, m/z 876.8→307.3 for paclitaxel and m/z 830.8→549.6 for IS, respectively. All calibration curves exhibited good linearity (r(2)>0.99) over a wide concentration range for all components. The intra-day and inter-day precisions at three different levels were both less than 14.3% in terms of relative standard deviation (RSD) and the accuracies ranged from -8.3% to 14.8% in terms of relative error (RE). The extraction recoveries of the seven compounds ranged from 62.5% to 100.5%. The developed method was successfully applied to the pharmacokinetic study of the seven taxoids in rat plasma after oral administration of the crude extract of the twigs and leaves of Taxus yunnanensis. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous quantitation of delamanid (OPC-67683) and its eight metabolites in human plasma using UHPLC-MS/MS.

PubMed

Meng, Min; Smith, Benjamin; Johnston, Brad; Carter, Spencer; Brisson, Jerry; Roth, Sharin E

2015-10-01

Delamanid (OPC-67683) is a novel nitro-dihydroimidazo-oxazole derivative that is being developed by Otsuka Pharmaceutical Co., Ltd., Japan (referred to as Otsuka hereafter) for the treatment of tuberculosis (TB). An ultra-high performance liquid chromatographic-tandem mass spectrometry (UHPLC-MS/MS) method has been developed and validated for the determination of OPC-67683 and its eight metabolites, DM-6704, DM-6705, DM-6706, DM-6717, DM-6718, DM-6720, DM-6721 and DM-6722 in human plasma to support regulated clinical development. During method development several technical challenges such as poor chromatography, separation of structural isomers, conversion of the analytes, instability in matrix and long cycle time were encountered and overcome. A protein precipitation extraction (PPE) was used to extract plasma samples (50μL) and the resulting extracts were analyzed using reversed phase UHPLC-MS/MS with a electrospray (ESI) and selected reaction monitoring (SRM). The method was fully validated over the calibration curve range of 1.00-500ng/mL for all nine analytes with linear regression and 1/x(2) weighting according to regulatory guidance for bioanalysis. Based on three inter-day precision and accuracy runs, the between-run % relative standard deviation (RSD) for all nine analytes varied from 0.0 to 11.9% and the accuracy ranged from 92.7% to 102.5% of nominal at all quality controls (QC) concentrations, including the lower limit of quantitation (LLOQ) QC at 1.00ng/mL. The extraction recovery of OPC-67683 and its eight metabolites were above 95%. Various short term and long term solution and matrix stability were established including the stability of OPC-67683 and its eight metabolites in human plasma for 708 days at -70°C. Although this method has been used to support regulated clinic studies during the last decade and over ten thousand samples have been analyzed, this is the first time that the method development process and validation data have been published. Copyright © 2015 Elsevier B.V. All rights reserved.

Trace determination of organophosphate esters in white wine, red wine, and beer samples using dispersive liquid-liquid microextraction combined with ultra-high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Pang, Long; Yang, Huiqiang; Yang, Peijie; Zhang, Hongzhong; Zhao, Jihong

2017-08-15

In this study, dispersive liquid-liquid microextraction coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry was developed for the analysis of five representative organophosphate esters (OPEs) in wine samples. Under optimized conditions, the proposed method resulted in good linearity (R 2 >0.9933) over the range of 0.1-100μgL -1 , with limits of detection (LODs, S/N =3) and quantification (LOQs, S/N =10) in the ranges of 0.48-18.8ngL -1 and 1.58-62.5ngL -1 , respectively. Inter- and intra-assay precisions of RSD% ranged from 3.21% to 6.13% and from 1.69% to 7.63%, respectively. The spiked recoveries of target OPEs from white wine, red wine, and beer samples were in the ranges of 80-122%, 76-120%, and 76-110%, respectively, at two different concentration levels. The total concentrations of five OPEs found in white wine, red wine, and beer samples were in the ranges of 0.29-0.85μgL -1 , 1.00-3.05μgL -1 , and 0.86-1.47μgL -1 , respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

A novel optimised and validated method for analysis of multi-residues of pesticides in fruits and vegetables by microwave-assisted extraction (MAE)-dispersive solid-phase extraction (d-SPE)-retention time locked (RTL)-gas chromatography-mass spectrometry with Deconvolution reporting software (DRS).

PubMed

Satpathy, Gouri; Tyagi, Yogesh Kumar; Gupta, Rajinder Kumar

2011-08-01

A rapid, effective and ecofriendly method for sensitive screening and quantification of 72 pesticides residue in fruits and vegetables, by microwave-assisted extraction (MAE) followed by dispersive solid-phase extraction (d-SPE), retention time locked (RTL) capillary gas-chromatographic separation in trace ion mode mass spectrometric determination has been validated as per ISO/IEC: 17025:2005. Identification and reporting with total and extracted ion chromatograms were facilitated to a great extent by Deconvolution reporting software (DRS). For all compounds LOD were 0.002-0.02mg/kg and LOQ were 0.025-0.100mg/kg. Correlation coefficients of the calibration curves in the range of 0.025-0.50mg/kg were >0.993. To validate matrix effects repeatability, reproducibility, recovery and overall uncertainty were calculated for the 35 matrices at 0.025, 0.050 and 0.100mg/kg. Recovery ranged between 72% and 114% with RSD of <20% for repeatability and intermediate precision. The reproducibility of the method was evaluated by an inter laboratory participation and Z score obtained within ±2. Copyright © 2011 Elsevier Ltd. All rights reserved.

Quantitative mass spectrometric analysis of ropivacaine and bupivacaine in authentic, pharmaceutical and spiked human plasma without chromatographic separation.

PubMed

Salama, Nahla N; Wang, Shudong

2008-05-28

The present study employs time of flight mass and bupivacaine in authentic, pharmaceutical and spiked human plasma as well as in the presence of their impurities 2,6-dimethylaniline and alkaline degradation product. The method is based on time of flight electron spray ionization mass spectrometry technique without preliminary chromatographic separation and makes use of bupivacaine as internal standard for ropivacaine, which is used as internal standard for bupivacaine. A linear relationship between drug concentrations and the peak intensity ratio of ions of the analyzed substances is established. The method is linear from 23.8 to 2380.0 ng mL(-1) for both drugs. The correlation coefficient was >or=0.996 in authentic and spiked human plasma. The average percentage recoveries in the ranges of 95.39%-102.75% was obtained. The method is accurate (% RE < 5%) and reproducible with intra- and inter-assay precision (RSD% < 8.0%). The quantification limit is 23.8 ng mL(-1) for both drugs. The method is not only highly sensitive and selective, but also simple and effective for determination or identification of both drugs in authentic and biological fluids. The method can be applied in purity testing, quality control and stability monitoring for the studied drugs.

Quantitative Mass Spectrometric Analysis of Ropivacaine and Bupivacaine in Authentic, Pharmaceutical and Spiked Human Plasma without Chromatographic Separation

PubMed Central

Salama, Nahla N.; Wang, Shudong

2009-01-01

The present study employs time of flight mass and bupivacaine in authentic, pharmaceutical and spiked human plasma as well as in the presence of their impurities 2,6-dimethylaniline and alkaline degradation product. The method is based on time of flight electron spray ionization mass spectrometry technique without preliminary chromatographic separation and makes use of bupivacaine as internal standard for ropivacaine, which is used as internal standard for bupivacaine. A linear relationship between drug concentrations and the peak intensity ratio of ions of the analyzed substances is established. The method is linear from 23.8 to 2380.0 ng mL−1 for both drugs. The correlation coefficient was ≥0.996 in authentic and spiked human plasma. The average percentage recoveries in the ranges of 95.39%–102.75% was obtained. The method is accurate (% RE < 5%) and reproducible with intra- and inter-assay precision (RSD% < 8.0%). The quantification limit is 23.8 ng mL−1 for both drugs. The method is not only highly sensitive and selective, but also simple and effective for determination or identification of both drugs in authentic and biological fluids. The method can be applied in purity testing, quality control and stability monitoring for the studied drugs. PMID:19652756

A sensitive and selective immunoaffinity column clean up coupled to UPLC-MS/MS for determination of trace methyl-3-quinoxaline-2-carboxylic acid in animal tissues.

PubMed

Li, Peipei; Zhang, Xiaojun; Zhang, Juanmei; Yan, Zhongyong; Zhang, Shuai; Chen, Si; Fang, Yi

2018-02-01

This paper described a reliable and simple method for the selective determination of MQCA in animal tissues using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). A highly targeted immunoaffinity column was used for sample purification after enzymatic hydrolysis. The purified extracts were analyzed by reversed-phase HPLC-MS/MS in positive ESI and multiple reaction monitoring mode. The calibration curves showed good linearity with correlation coefficient (r 2 ) larger than 0.995. The average recoveries at the spiked levels of 0.5, 2.0 and 20μgkg -1 were 90.2% to 103.5% with intra-day and inter-day relatives standard deviations (RSD, n=6) ranging from 1.8% to 6.7% and 3.5% to 7.6% respectively. The limit of quantification (LOQ) was 0.5μgkg -1 , which can fulfil the maximum residue level (MRL) of 4.0μgkg -1 stipulated by the Agricultural Minister of China and the requirement of the confirmatory criteria according to the European Commission Decision 2002/657/EC. The method is sensitive, accurate, convenient and rapid, and has been successfully applied in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Rapid Development and Validation of Improved Reversed-Phase High-performance Liquid Chromatography Method for the Quantification of Mangiferin, a Polyphenol Xanthone Glycoside in Mangifera indica

PubMed Central

Naveen, P.; Lingaraju, H. B.; Prasad, K. Shyam

2017-01-01

Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica, is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica. RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography–mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica. SUMMARY The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica. The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica. Abbreviations Used: M. indica: Mangifera indica, RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification. PMID:28539748

Rapid Development and Validation of Improved Reversed-Phase High-performance Liquid Chromatography Method for the Quantification of Mangiferin, a Polyphenol Xanthone Glycoside in Mangifera indica.

PubMed

Naveen, P; Lingaraju, H B; Prasad, K Shyam

2017-01-01

Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica , is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica . RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography-mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica . The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica . The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica . Abbreviations Used: M. indica : Mangifera indica , RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification.

Determination of U isotope ratios in sediments using ICP-QMS after sample cleanup with anion-exchange and extraction chromatography.

PubMed

Zheng, Jian; Yamada, Masatoshi

2006-01-15

The determination of uranium is important for environmental radioactivity monitoring, which investigates the releases of uranium from nuclear facilities and of naturally occurring radioactive materials by the coal, oil, natural gas, mineral, ore refining and phosphate fertilizer industries, and it is also important for studies on the biogeochemical behavior of uranium in the environment. In this paper, we describe a quadrupole ICP-MS (ICP-QMS)-based analytical procedure for the accurate determination of U isotope ratios ((235)U/(238)U atom ratio and (234)U/(238)U activity ratio) in sediment samples. A two-stage sample cleanup using anion-exchange and TEVA extraction chromatography was employed in order to obtain accurate and precise (234)U/(238)U activity ratios. The factors that affect the accuracy and precision of U isotope ratio analysis, such as detector dead time, abundance sensitivity, dwell time and mass bias were carefully evaluated and corrected. With natural U, a precision lower than 0.5% R.S.D. for (235)U/(238)U atom ratio and lower than 2.0% R.S.D. for (234)U/(238)U activity ratio was obtained with less than 90 ng uranium. The developed analytical method was validated using an ocean sediment reference material and applied to an investigation into the uranium isotopic compositions in a sediment core in a brackish lake in the vicinity of U-related nuclear facilities in Japan.

Analytical parameters of the microplate-based ORAC-pyrogallol red assay.

PubMed

Ortiz, Rocío; Antilén, Mónica; Speisky, Hernán; Aliaga, Margarita E; López-Alarcón, Camilo

2011-01-01

The analytical parameters of the microplate-based oxygen radicals absorbance capacity (ORAC) method using pyrogallol red (PGR) as probe (ORAC-PGR) are presented. In addition, the antioxidant capacity of commercial beverages, such as wines, fruit juices, and iced teas, is estimated. A good linearity of the area under the curve (AUC) versus Trolox concentration plots was obtained [AUC = (845 +/- 110) + (23 +/- 2) [Trolox, microM], R = 0.9961, n = 19]. QC experiments showed better precision and accuracy at the highest Trolox concentration (40 microM) with RSD and REC (recuperation) values of 1.7 and 101.0%, respectively. When red wine was used as sample, the method also showed good linearity [AUC = (787 +/- 77) + (690 +/- 60) [red wine, microL/mL]; R = 0.9926, n = 17], precision and accuracy with RSD values from 1.4 to 8.3%, and REC values that ranged from 89.7 to 103.8%. Additivity assays using solutions containing gallic acid and Trolox (or red wine) showed an additive protection of PGR given by the samples. Red wines showed higher ORAC-PGR values than white wines, while the ORAC-PGR index of fruit juices and iced teas presented a great variability, ranging from 0.6 to 21.6 mM of Trolox equivalents. This variability was also observed for juices of the same fruit, showing the influence of the brand on the ORAC-PGR index. The ORAC-PGR methodology can be applied in a microplate reader with good linearity, precision, and accuracy.

Inter-examination Precision of Magnitude-based Magnetic Resonance Imaging for Estimation of Segmental Hepatic Proton Density Fat Fraction (PDFF) in Obese Subjects

PubMed Central

Negrete, Lindsey M.; Middleton, Michael S.; Clark, Lisa; Wolfson, Tanya; Gamst, Anthony C.; Lam, Jessica; Changchien, Chris; Deyoung-Dominguez, Ivan M.; Hamilton, Gavin; Loomba, Rohit; Schwimmer, Jeffrey; Sirlin, Claude B.

2013-01-01

Purpose To prospectively describe magnitude-based multi-echo gradient-echo hepatic proton density fat fraction (PDFF) inter-examination precision at 3T. Materials and Methods In this prospective, IRB approved, HIPAA compliant study, written informed consent was obtained from 29 subjects (body mass indexes > 30kg/m2). Three 3T magnetic resonance imaging (MRI) examinations were obtained over 75-90 minutes. Segmental, lobar, and whole liver PDFF were estimated (using three, four, five, or six echoes) by magnitude-based multi-echo MRI in co-localized regions of interest (ROIs). For estimate (using three, four, five, or six echoes), at each anatomic level (segmental, lobar, whole liver), three inter-examination precision metrics were computed: intra-class correlation coefficient (ICC), standard deviation (SD), and range. Results Magnitude-based PDFF estimates using each reconstruction method showed excellent inter-examination precision for each segment (ICC ≥ 0.992; SD ≤ 0.66%; range ≤ 1.24%), lobe (ICC ≥ 0.998; SD ≤ 0.34%; range ≤ 0.64%), and the whole liver (ICC = 0.999; SD ≤ 0.24%; range ≤ 0.45%). Inter-examination precision was unaffected by whether PDFF was estimated using three, four, five, or six echoes. Conclusion Magnitude-based PDFF estimation shows high inter-examination precision at segmental, lobar, and whole liver anatomic levels, supporting its use in clinical care or clinical trials. The results of this study suggest that longitudinal hepatic PDFF change greater than 1.6% is likely to represent signal rather than noise. PMID:24136736

Determination of ractopamine in pig hair using liquid chromatography with tandem mass spectrometric detection.

PubMed

Wu, Junlin; Liu, Xiaoyun; Peng, Yunping

2014-01-01

A quantitative analytical procedure for the determination of ractopamine in pig hair has been developed and validated. The hair samples were washed and incubated at 75°C with isoxuprine and hair extraction buffer. The drug present was quantified using mixed solid-phase extraction and liquid chromatography with tandem mass spectrometric detection. The limit of quantization (LOQ) was 10pg/mg and the intra-day precision at 25pg/mg and 750pg/mg was 0.49% and 2.8% respectively. Inter-day precision was 0.88% and 3.52% at the same concentrations. The hair extraction percentage recovery at 25pg/mg and 50ng/mL was 99.47% and 103.83% respectively. The extraction percentage recovery at 25pg/mg and 50ng/mg was 93.52% and 100.26% respectively. Our results showed that ractopamine residues persist in hair in 24days of withdrawal and also showed the possibility to test ractopamine from pig hair samples. Copyright © 2014 Elsevier Inc. All rights reserved.

Spectrophotometric determination of the total flavonoid content in Ocimum basilicum L. (Lamiaceae) leaves

PubMed Central

da Silva, Layzon Antonio Lemos; Pezzini, Bianca Ramos; Soares, Luciano

2015-01-01

Background: The chemical characterization is essential to validate the pharmaceutical use of vegetable raw materials. Ultraviolet spectroscopy is an important technique to determine flavonoids, which are important active compounds from Ocimum basilicum. Objective: The objective of this work was to optimize a spectrophotometric method, based on flavonoid-aluminum chloride (AlCl3) complexation to determine the total flavonoid content (TFC) in leaves of O. basilicum (herbal material), using response surface methodology. Materials and Methods: The effects of (1) the herbal material: Solvent ratio (0.02, 0.03, 0.05, 0.07, and 0.08 g/mL), (2) stock solution volume (0.8, 2.3, 4.4, 6.5, and 8.0 mL) and (3) AlCl3 volume (0.8, 1.0, 1.2, 1.4, and 1.6 mL) on the TFC were evaluated. The analytical performance parameters precision, linearity and robustness of the method were tested. Results: The herbal material: Solvent ratio and stock solution volume showed an important influence on the method response. After choosing the optimized conditions, the method exhibited a precision (RSD%) lower than 6% for repeatability (RSD%) and lower than 8% for intermediate precision (on the order of literature values for biotechnological methods), coefficient of correlation of 0.9984, and no important influence could be observed for variations of the time of complexation with AlCl3. However, the time and temperature of extraction were critical for TFC method and must be carefully controlled during the analysis. Conclusion: Thus, this study allowed the optimization of a simple, fast and precise method for the determination of the TFC in leaves of O. basilicum, which can be used to support the quality assessment of this herbal material. PMID:25709217

Authentication of Piper betle L. folium and quantification of their antifungal-activity.

PubMed

Wirasuta, I Made Agus Gelgel; Srinadi, I Gusti Ayu Made; Dwidasmara, Ida Bagus Gede; Ardiyanti, Ni Luh Putu Putri; Trisnadewi, I Gusti Ayu Arya; Paramita, Ni Luh Putu Vidya

2017-07-01

The TLC profiles of intra- and inter-day precision for Piper betle L . (PBL) folium methanol extract was studied for their peak marker recognition and identification. The Numerical chromatographic parameters (NCPs) of the peak markers, the hierarchical clustering analysis (HCA) and the principal component analysis (PCA) were applied to authenticate the PBL. folium extract from other Piper species folium extract and to ensure the antifungal activity quality of the PBL essential oil. The spotted extract was developed with the mobile phase of toluene: ethyl acetate; 93:7, (v/v). The eluted plate was viewed with the TLC-Visualizer, scanned under absorption and fluorescent mode detection, and on each sample the in-situ UV spectra were recorded between 190 to 400 nm. The NCPs profiles of intra- and inter-day precision results offered multi-dimensional chromatogram fingerprints for better marker peak pattern recognition and identification. Using the r -value fingerprints data series generated with this method allowed more precise discrimination the PBL. from other Piper species compared to the marker peak area fingerprint method. The cosine pair comparison was a simple method for authentication of two different fingerprints. The ward linkage clustering and the pair cross-correlation comparison were better chemometric methods to determine the consistency peak area ratio between fingerprints. The first component PCA-loading values of peak marker area fingerprints were correlated linearly to both the bio-marker concentration as well as the antifungal activity. This relationship could be used to control the quality and pharmacological potency. This simple method was developed for the authentication and quantification of herbal medicine.

Group for High Resolution Sea Surface Temperature (GHRSST) Analysis Fields Inter-Comparisons. Part 2. Near Real Time Web-based Level 4 SST Quality Monitor (L4-SQUAM)

DTIC Science & Technology

2012-01-01

Reynoldsr, Viva Banzon*. Helen Beggs h, Jean-Francois Cayula1, Yi Chaoj, Robert Grumbinek, Eileen Maturia, Andy Harrisal. Jonathan Mittaza•’, John...number of valid OSTIA SSTs because NN matching is done to OSTIA grid. A dotted gray line shows an ideal Gaussian fit, X~N(Median, RSD...show significant differences. In the right panels, AT, statistics are annotated on the left side of the histograms, dotted gray line shows an ideal

Inorganic arsenic contents in ready-to-eat rice products and various Korean rice determined by a highly sensitive gas chromatography-tandem mass spectrometry.

PubMed

Jung, Mun Yhung; Kang, Ju Hee; Jung, Hyun Jeong; Ma, Sang Yong

2018-02-01

Rice and rice products have been reported to contain high contents of toxic inorganic arsenic (iAs). The inorganic arsenic contents in microwavable ready-to-eat rice products (n=30) and different types of Korean rice (n=102) were determined by a gas chromatography-tandem mass spectrometry (GC-MS/MS). The method showed low limit of detection (0.015pg), high intra- and inter-day repeatability (<7.3%, RSD), and recovery rates (90-117%). The mean iAs content in the ready-to-eat rice products was 59μgkg -1 (dry weight basis). The mean iAs contents in polished white, brown, black, and waxy rice were 65, 109, 91, and 66μgkg -1 , respectively. The percentages of ready-to-eat rice products, white, brown, black, and waxy rice containing iAs over the maximum level (100μgkg -1 ) set by EU for the infant foods were 17, 4, 70, 36 and 0%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hollow fibre-based liquid phase microextraction combined with high-performance liquid chromatography for the analysis of flavonoids in Echinophora platyloba DC. and Mentha piperita.

PubMed

Hadjmohammadi, Mohammadreza; Karimiyan, Hanieh; Sharifi, Vahid

2013-11-15

A simple, inexpensive and efficient three phase hollow fibre liquid phase microextraction (HF-LPME) technique combined with HPLC was used for the simultaneous determination of flavonoids in Echinophora platyloba DC. and Mentha piperita. Different factors affecting the HF-LPME procedure were investigated and optimised. The optimised extraction conditions were as follows: 1-octanol as an organic solvent, pHdonor=2, pHacceptor=9.75, stirring rate of 1000rpm, extraction time of 80min, without addition of salt. Under these conditions, the enrichment factors ranged between 146 and 311. The values of intra and inter-day relative standard deviations (RSD) were in the range of 3.18-6.00% and 7.25-11.00%, respectively. The limits of detection (LODs) ranged between 0.5 and 7.0ngmL(-1). Among the investigated flavonoids quercetin was found in E. platyloba DC. and luteolin was found in M. piperita. Concentration of quercetin and luteolin was 0.015 and 0.025mgg(-1) respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Simultaneous determination of vinclozolin and detection of its degradation products in mouse plasma, serum and urine, and from rabbit bile, by high-performance liquid chromatography.

PubMed

Dhananjeyan, Mugunthu R; Erhardt, Paul W; Corbitt, Cynthia

2006-05-19

A specific high-performance liquid chromatography method has been developed for simultaneous detection of vinclozolin and its degradation products (M1, M2, and M3). The method has been validated according to ICH guidelines and can be extended to quantitation of vinclozolin. A base-line separation of vinclozolin and its degradation products was found with symmetrical peak shapes on an XTerra MS C18 column using 10 mM ammonium bicarbonate at pH 9.2 and acetonitrile as mobile phase. The retention times of vinclozolin, M1, M2, and M3 were 12.8, 8.1, 11.6, and 11.1 min, respectively. A linear calibration curve was obtained across a range from 5 to 200 microM for vinclozolin. The intra- and inter-day relative standard deviations (%RSD) were <1%. Greater than 90% recoveries of vinclozolin from bio-fluids including mouse plasma, serum and urine, and rabbit bile, were obtained in a single step with a single solvent.

Single-laboratory validation of the microplate receptor binding assay for paralytic shellfish toxins in shellfish.

PubMed

Van Dolah, Frances M; Leighfield, Tod A; Doucette, Gregory J; Bean, Laurie; Niedzwiadek, Barbara; Rawn, Dorothea F K

2009-01-01

A single-laboratory validation (SLV) study was conducted for the microplate receptor binding assay (RBA) for paralytic shellfish poisoning (PSP) toxins in shellfish. The basis of the assay is the competition between [3H]saxitoxin (STX) and STX in a standard or sample for binding to the voltage dependent sodium channel. A calibration curve is generated by the addition of 0.01-1000 nM STX, which results in the concentration dependent decrease in [3H]STX-receptor complexes formed and serves to quantify STX in unknown samples. This study established the LOQ, linearity, recovery, accuracy, and precision of the assay for determining PSP toxicity in shellfish extracts, as performed by a single analyst on multiple days. The standard curve obtained on 5 independent days resulted in a half-maximal inhibition (IC50) of 2.3 nM STX +/- 0.3 (RSD = 10.8%) with a slope of 0.96 +/- 0.06 (RSD = 6.3%) and a dynamic range of 1.2-10.0 nM. The LOQ was 5.3 microg STX equivalents/100 g shellfish. Linearity, established by quantification of three levels of purified STX (1.5, 3, and 6 nM), yielded an r2 of 0.97. Recovery from mussels spiked with three levels (40, 80, and 120 microg STX/100 g) averaged 121%. Repeatability (RSD(r)), determined on six naturally contaminated shellfish samples on 5 independent days, was 17.7%. A method comparison with the AOAC mouse bioassay yielded r2 = 0.98 (slope = 1.29) in the SLV study. The effects of the extraction method on RBA-based toxicity values were assessed on shellfish extracted for PSP toxins using the AOAC mouse bioassay method (0.1 M HCI) compared to that for the precolumn oxidation HPLC method (0.1% acetic acid). The two extraction methods showed linear correlation (r2 = 0.99), with the HCl extraction method yielding slightly higher toxicity values (slope = 1.23). A similar relationship was observed between HPLC quantification of the HCI- and acetic acid-extracted samples (r2 = 0.98, slope 1.19). The RBA also had excellent linear correlation with HPLC analyses (r2 = 0.98 for HCl, r2 = 0.99 for acetic acid), but gave somewhat higher values than HPLC using either extraction method (slope = 1.39 for HCl extracts, slope = 1.32 for acetic acid). Overall, the excellent linear correlations with the both mouse bioassay and HPLC method and sufficient interassay repeatability suggest that the RBA can be effective as a high throughput screen for estimating PSP toxicity in shellfish.

Static adsorptive coating of poly(methyl methacrylate) microfluidic chips for extended usage in DNA separations.

PubMed

Du, Xiao-Guang; Fang, Zhao-Lun

2005-12-01

A simple and robust static adsorptive (dynamic) coating process using 2% hydroxyethylcellulose was developed for surface modification of poly(methyl methacrylate) (PMMA) microfluidic chips for DNA separations, suitable for usage over extended periods, involving hundreds of runs. The coating medium was also used as a sieving matrix for the DNA separations following the coating process. Four consecutive static treatments, by simply filling the PMMA chip channels with sieving matrix once every day, were required for obtaining a stable coating and optimum performance. The performance of the coated chips at different phases of the coating process was studied by consecutive gel electrophoretic separations with LIF detection using a PhiX-174/HaeIII DNA digest sample. The coated chip, with daily renewal of the sieving matrix, showed high stability in performance during a 25-day period of systematic study, involving more than 100 individual runs. The performance of the coated chip also remained almost the same after 3 months of continuous usage, during which over 200 separations were performed. The average precision of migration time for the 603-bp fragment was 1.31% RSD (n = 6) during the 25-day study, with a separation efficiency of 6.5 x 10(4) plates (effective separation length 5.4 cm).

Operator Variability in Scan Positioning is a Major Component of HR-pQCT Precision Error and is Reduced by Standardized Training

PubMed Central

Bonaretti, Serena; Vilayphiou, Nicolas; Chan, Caroline Mai; Yu, Andrew; Nishiyama, Kyle; Liu, Danmei; Boutroy, Stephanie; Ghasem-Zadeh, Ali; Boyd, Steven K.; Chapurlat, Roland; McKay, Heather; Shane, Elizabeth; Bouxsein, Mary L.; Black, Dennis M.; Majumdar, Sharmila; Orwoll, Eric S.; Lang, Thomas F.; Khosla, Sundeep; Burghardt, Andrew J.

2017-01-01

Introduction HR-pQCT is increasingly used to assess bone quality, fracture risk and anti-fracture interventions. The contribution of the operator has not been adequately accounted in measurement precision. Operators acquire a 2D projection (“scout view image”) and define the region to be scanned by positioning a “reference line” on a standard anatomical landmark. In this study, we (i) evaluated the contribution of positioning variability to in vivo measurement precision, (ii) measured intra- and inter-operator positioning variability, and (iii) tested if custom training software led to superior reproducibility in new operators compared to experienced operators. Methods To evaluate the operator in vivo measurement precision we compared precision errors calculated in 64 co-registered and non-co-registered scan-rescan images. To quantify operator variability, we developed software that simulates the positioning process of the scanner’s software. Eight experienced operators positioned reference lines on scout view images designed to test intra- and inter-operator reproducibility. Finally, we developed modules for training and evaluation of reference line positioning. We enrolled 6 new operators to participate in a common training, followed by the same reproducibility experiments performed by the experienced group. Results In vivo precision errors were up to three-fold greater (Tt.BMD and Ct.Th) when variability in scan positioning was included. Inter-operator precision errors were significantly greater than short-term intra-operator precision (p<0.001). New trained operators achieved comparable intra-operator reproducibility to experienced operators, and lower inter-operator reproducibility (p<0.001). Precision errors were significantly greater for the radius than for the tibia. Conclusion Operator reference line positioning contributes significantly to in vivo measurement precision and is significantly greater for multi-operator datasets. Inter-operator variability can be significantly reduced using a systematic training platform, now available online (http://webapps.radiology.ucsf.edu/refline/). PMID:27475931

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gundlach-Graham, Alexander W.; Dennis, Elise; Ray, Steven J.

An inductively coupled plasma distance-of-flight mass spectrometer (ICP-DOFMS) has been coupled with laser-ablation (LA) sample introduction for the elemental analysis of solids. ICP-DOFMS is well suited for the analysis of laser-generated aerosols because it offers both high-speed mass analysis and simultaneous multi-elemental detection. Here, we evaluate the analytical performance of the LA-ICP-DOFMS instrument, equipped with a microchannel plate-based imaging detector, for the measurement of steady-state LA signals, as well as transient signals produced from single LA events. Steady-state detection limits are 1 mg g1, and absolute single-pulse LA detection limits are 200 fg for uranium; the system is shown capablemore » of performing time-resolved single-pulse LA analysis. By leveraging the benefits of simultaneous multi-elemental detection, we also attain a good shot-to-shot reproducibility of 6% relative standard deviation (RSD) and isotope-ratio precision of 0.3% RSD with a 10 s integration time.« less

Development and validation of a novel, simple, and accurate spectrophotometric method for the determination of lead in human serum.

PubMed

Shayesteh, Tavakol Heidari; Khajavi, Farzad; Khosroshahi, Abolfazl Ghafuri; Mahjub, Reza

2016-01-01

The determination of blood lead levels is the most useful indicator of the determination of the amount of lead that is absorbed by the human body. Various methods, like atomic absorption spectroscopy (AAS), have already been used for the detection of lead in biological fluid, but most of these methods are based on complicated, expensive, and highly instructed instruments. In this study, a simple and accurate spectroscopic method for the determination of lead has been developed and applied for the investigation of lead concentration in biological samples. In this study, a silica gel column was used to extract lead and eliminate interfering agents in human serum samples. The column was washed with deionized water. The pH was adjusted to the value of 8.2 using phosphate buffer, and then tartrate and cyanide solutions were added as masking agents. The lead content was extracted into the organic phase containing dithizone as a complexion reagent and the dithizone-Pb(II) complex was formed and approved by visible spectrophotometry at 538 nm. The recovery was found to be 84.6 %. In order to validate the method, a calibration curve involving the use of various concentration levels was calculated and proven to be linear in the range of 0.01-1.5 μg/ml, with an R (2) regression coefficient of 0.9968 by statistical analysis of linear model validation. The largest error % values were found to be -5.80 and +11.6 % for intra-day and inter-day measurements, respectively. The largest RSD % values were calculated to be 6.54 and 12.32 % for intra-day and inter-day measurements, respectively. Further, the limit of detection (LOD) was calculated to be 0.002 μg/ml. The developed method was applied to determine the lead content in the human serum of voluntary miners, and it has been proven that there is no statistically significant difference between the data provided from this novel method and the data obtained from previously studied AAS.

Preliminary investigation of electrothermal vaporization sample introduction for inductively coupled plasma time-of-flight mass spectrometry.

PubMed

Mahoney, P P; Ray, S J; Li, G; Hieftje, G M

1999-04-01

The coupling of an electrothermal vaporization (ETV) apparatus to an inductively coupled plasma time-of-flight mass spectrometer (ICP-TOFMS) is described. The ability of the ICP-TOFMS to produce complete elemental mass spectra at high repetition rates is experimentally demonstrated. A signal-averaging data acquisition board is employed to rapidly record complete elemental spectra throughout the vaporization stage of the ETV temperature cycle; a solution containing 34 elements is analyzed. The reduction of both molecular and atomic isobaric interferences through the temperature program of the furnace is demonstrated. Isobaric overlaps among the isotopes of cadmium, tin, and indium are resolved by exploiting differences in the vaporization characteristics of the elements. Figures of merit for the system are defined with several different data acquisition schemes capable of operating at the high repetition rate of the TOF instrument. With the use of both ion counting and a boxcar averager, the dynamic range is shown to be linear over a range of at least 6 orders of magnitude. A pair of boxcar averagers are used to measure the isotope ratio for silver with a precision of 1.9% RSD, despite a cycle-to-cycle precision of 19% RSD. Detection limits of 10-80 fg are calculated for seven elements, based upon a 10-microL injection.

Determination of (187)Os in molybdenite by ICP-MS with neutron-induced (186)Os and (188)Os spikes.

PubMed

Qu, W; Du, A; Zhao, D

2001-10-31

The article describes a method for the determination of (187)Os in molybdenite by isotope dilution inductively coupled plasma-mass spectrometry (ID-ICP-MS) with neutron-induced (186)Os and (188)Os spike. The spike used in the present work was prepared in line with the principle by which artificial nuclides are produced in a nuclear reaction. The concentration and isotopic composition of osmium in the prepared spike were evaluated accurately with the isotope dilution method, using negative thermal ion mass spectrometry (N-TIMS). The advantage of this method is that using (186)Os and (188)Os double spikes can effectively compensate for the mass discrimination effects of ICP-MS. Thus, the common correction practice for mass bias in the isotope dilution method with a single spike is unnecessary. In addition, the method enables one to reduce the determined error arising from instrumental instability. The precision for the (187)Os/((186)Os+(188)Os) ratio was approximately 2% (2sigma, RSD), but in the case of (187)Os/(186)Os, (187)Os/(188)Os and (186)Os/(188)Os, precision ranged from 2.0 to 8% (2sigma, RSD). The results for (187)Os concentration in a molybdenite sample determined with this method showed good agreement with reference values.

Method for determination of aflatoxin M₁ in cheese and butter by HPLC using an immunoaffinity column.

PubMed

Sakuma, Hisako; Kamata, Yoichi; Sugita-Konishi, Yoshiko; Kawakami, Hiroshi

2011-01-01

A rapid, sensitive convenient method for determination of aflatoxin M₁ (AFM₁) in cheese and butter by HPLC was developed and validated. The method employs a safe extraction solution (mixture of acetonitrile, methanol and water) and an immunoaffinity column (IAC) for clean-up. Compared with the widely used method employing chloroform and a Florisil column, the IAC method has a short analytical time and there are no interference peaks. The limits of quantification (LOQ) of the IAC method were 0.12 and 0.14 µg/kg, while those of the Florisil column method were 0.47 and 0.23 µg/kg in cheese and buffer, respectively. The recovery and relative standard deviation (RSD) for cheese (spiked at 0.5 µg/kg) in the IAC method were 92% and 7%, respectively, while for the Florisil column method the corresponding values were 76% and 10%. The recovery and RSD for butter (spiked at 0.5 µg/kg) in the IAC method were 97% and 9%, and those in the Florisil method were 74% and 9%, respectively. In the IAC method, the values of in-house precision (n=2, day=5) of cheese and butter (spiked at 0.5 µg/kg) were 9% and 13%, respectively. The IAC method is superior to the Florisil column method in terms of safety, ease of handling, sensitivity and reliability. A survey of AFM₁ contamination in imported cheese and butter in Japan was conducted by the IAC method. AFM₁ was not detected in 60 samples of cheese and 30 samples of butter.

Quantitative determination of multi markers in five varieties of Withania somnifera using ultra-high performance liquid chromatography with hybrid triple quadrupole linear ion trap mass spectrometer combined with multivariate analysis: Application to pharmaceutical dosage forms.

PubMed

Chandra, Preeti; Kannujia, Rekha; Saxena, Ankita; Srivastava, Mukesh; Bahadur, Lal; Pal, Mahesh; Singh, Bhim Pratap; Kumar Ojha, Sanjeev; Kumar, Brijesh

2016-09-10

An ultra-high performance liquid chromatography electrospray ionization tandem mass spectrometry method has been developed and validated for simultaneous quantification of six major bioactive compounds in five varieties of Withania somnifera in various plant parts (leaf, stem and root). The analysis was accomplished on Waters ACQUITY UPLC BEH C18 column with linear gradient elution of water/formic acid (0.1%) and acetonitrile at a flow rate of 0.3mLmin(-1). The proposed method was validated with acceptable linearity (r(2), 0.9989-0.9998), precision (RSD, 0.16-2.01%), stability (RSD, 1.04-1.62%) and recovery (RSD ≤2.45%), under optimum conditions. The method was also successfully applied for the simultaneous determination of six marker compounds in twenty-six marketed formulations. Hierarchical cluster analysis and principal component analysis were applied to discriminate these twenty-six batches based on characteristics of the bioactive compounds. The results indicated that this method is advance, rapid, sensitive and suitable to reveal the quality of Withania somnifera and also capable of performing quality evaluation of polyherbal formulations having similar markers/raw herbs. Copyright © 2016 Elsevier B.V. All rights reserved.

Validation of an automated solid-phase extraction method for the analysis of 23 opioids, cocaine, and metabolites in urine with ultra-performance liquid chromatography-tandem mass spectrometry.

PubMed

Ramírez Fernández, María del Mar; Van Durme, Filip; Wille, Sarah M R; di Fazio, Vincent; Kummer, Natalie; Samyn, Nele

2014-06-01

The aim of this work was to automate a sample preparation procedure extracting morphine, hydromorphone, oxymorphone, norcodeine, codeine, dihydrocodeine, oxycodone, 6-monoacetyl-morphine, hydrocodone, ethylmorphine, benzoylecgonine, cocaine, cocaethylene, tramadol, meperidine, pentazocine, fentanyl, norfentanyl, buprenorphine, norbuprenorphine, propoxyphene, methadone and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine from urine samples. Samples were extracted by solid-phase extraction (SPE) with cation exchange cartridges using a TECAN Freedom Evo 100 base robotic system, including a hydrolysis step previous extraction when required. Block modules were carefully selected in order to use the same consumable material as in manual procedures to reduce cost and/or manual sample transfers. Moreover, the present configuration included pressure monitoring pipetting increasing pipetting accuracy and detecting sampling errors. The compounds were then separated in a chromatographic run of 9 min using a BEH Phenyl analytical column on a ultra-performance liquid chromatography-tandem mass spectrometry system. Optimization of the SPE was performed with different wash conditions and elution solvents. Intra- and inter-day relative standard deviations (RSDs) were within ±15% and bias was within ±15% for most of the compounds. Recovery was >69% (RSD < 11%) and matrix effects ranged from 1 to 26% when compensated with the internal standard. The limits of quantification ranged from 3 to 25 ng/mL depending on the compound. No cross-contamination in the automated SPE system was observed. The extracted samples were stable for 72 h in the autosampler (4°C). This method was applied to authentic samples (from forensic and toxicology cases) and to proficiency testing schemes containing cocaine, heroin, buprenorphine and methadone, offering fast and reliable results. Automation resulted in improved precision and accuracy, and a minimum operator intervention, leading to safer sample handling and less time-consuming procedures.

Development of a multi-residue analytical methodology based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for screening and trace level determination of pharmaceuticals in surface and wastewaters.

PubMed

Gros, Meritxell; Petrović, Mira; Barceló, Damiá

2006-11-15

This paper describes development, optimization and validation of a method for the simultaneous determination of 29 multi-class pharmaceuticals using off line solid phase extraction (SPE) followed by liquid chromatography-triple quadrupole mass spectrometry (LC-MS-MS). Target compounds include analgesics and non-steroidal anti-inflammatories (NSAIDs), lipid regulators, psychiatric drugs, anti-histaminics, anti-ulcer agent, antibiotics and beta-blockers. Recoveries obtained were generally higher than 60% for both surface and wastewaters, with exception of several compounds that yielded lower, but still acceptable recoveries: ranitidine (50%), sotalol (50%), famotidine (50%) and mevastatin (34%). The overall variability of the method was below 15%, for all compounds and all tested matrices. Method detection limits (MDL) varied between 1 and 30ng/L and from 3 to 160ng/L for surface and wastewaters, respectively. The precision of the method, calculated as relative standard deviation (R.S.D.), ranged from 0.2 to 6% and from 1 to 11% for inter and intra-day analysis, respectively. A detailed study of matrix effects was performed in order to evaluate the suitability of different calibration approaches (matrix-matched external calibration, internal calibration, extract dilution) to reduce analyte suppression or enhancement during instrumental analysis. The main advantages and drawbacks of each approach are demonstrated, justifying the selection of internal standard calibration as the most suitable approach for our study. The developed analytical method was successfully applied to the analysis of pharmaceutical residues in WWTP influents and effluents, as well as in river water. For both, river and wastewaters, the most ubiquitous compounds belonged to the group of anti-inflammatories and analgesics, antibiotics, the lipid regulators being acetaminophen, trimethoprim, ibuprofen, ketoprofen, atenolol, propranolol, mevastatin, carbamazepine and ranitidine the most frequently detected compounds.

Development of a novel ultrasound-assisted headspace liquid-phase microextraction and its application to the analysis of chlorophenols in real aqueous samples.

PubMed

Xu, Hui; Liao, Ying; Yao, Jinrong

2007-10-05

A new sample pretreatment technique, ultrasound-assisted headspace liquid-phase microextraction was developed as mentioned in this paper. In the technique, the volatile analytes were headspace extracted into a small drop of solvent, which suspended on the bottom of a cone-shaped PCR tube instead of the needle tip of a microsyringe. More solvent could be suspended in the PCR tube than microsyringe due to the larger interfacial tension, thus the analysis sensitivity was significantly improved with the increase of the extractant volume. Moreover, ultrasound-assisted extraction and independent controlling temperature of the extractant and the sample were performed to enhance the extraction efficiency. Following the extraction, the solvent-loaded sample was analyzed by high-performance liquid chromatography. Chlorophenols (2-chlorophenol, 2,4-dichlorophenol and 2,6-dichlorophenol) were chosen as model analytes to investigate the feasibility of the method. The experimental conditions related to the extraction efficiency were systematically studied. Under the optimum experimental conditions, the detection limit (S/N=3), intra- and inter-day RSD were 6 ng mL(-1), 4.6%, 3.9% for 2-chlorophenol, 12 ng mL(-1), 2.4%, 8.8% for 2,4-dichlorophenol and 23 ng mL(-1), 3.3%, 5.3% for 2,6-dichlorophenol, respectively. The proposed method was successfully applied to determine chlorophenols in real aqueous samples. Good recoveries ranging from 84.6% to 100.7% were obtained. In addition, the extraction efficiency of our method and the conventional headspace liquid-phase microextraction were compared; the extraction efficiency of the former was about 21 times higher than that of the latter. The results demonstrated that the proposed method is a promising sample pretreatment approach, its advantages over the conventional headspace liquid-phase microextraction include simple setup, ease of operation, rapidness, sensitivity, precision and no cross-contamination. The method is very suitable for the analysis of trace volatile and semivolatile pollutants in real aqueous sample.

Restricted access carbon nanotubes for direct extraction of cadmium from human serum samples followed by atomic absorption spectrometry analysis.

PubMed

Barbosa, Adriano F; Barbosa, Valéria M P; Bettini, Jefferson; Luccas, Pedro O; Figueiredo, Eduardo C

2015-01-01

In this paper, we propose a new sorbent that is able to extract metal ions directly from untreated biological fluids, simultaneously excluding all proteins from these samples. The sorbent was obtained through the modification of carbon nanotubes (CNTs) with an external bovine serum albumin (BSA) layer, resulting in restricted access carbon nanotubes (RACNTs). The BSA layer was fixed through the interconnection between the amine groups of the BSA using glutaraldehyde as cross-linker. When a protein sample is percolated through a cartridge containing RACNTs and the sample pH is higher than the isoelectric point of the proteins, both proteins from the sample and the BSA layer are negatively ionized. Thus, an electrostatic repulsion prevents the interaction between the proteins from the sample on the RACNTs surface. At the same time, metal ions are adsorbed in the CNTs (core) after their passage through the chains of proteins. The Cd(2+) ion was selected for a proof-of-principle case to test the suitability of the RACNTs due to its toxicological relevance. RACNTs were able to extract Cd(2+) and exclude almost 100% of the proteins from the human serum samples in an online solid-phase extraction system coupled with thermospray flame furnace atomic absorption spectrometry. The limits of detection and quantification were 0.24 and 0.80 μg L(-1), respectively. The sampling frequency was 8.6h(-1), and the intra- and inter-day precisions at the 0.80, 15.0, and 30.0 μg L(-1) Cd(2+) levels were all lower than 10.1% (RSD). The recoveries obtained for human blood serum samples fortified with Cd(2+) ranged from 85.0% to 112.0%. The method was successfully applied to analyze Cd(2+) directly from six human blood serum samples without any pretreatment, and the observed concentrations ranged from

A validated UPLC-MS/MS method for the surveillance of ten aquatic biotoxins in European brackish and freshwater systems.

PubMed

Greer, Brett; McNamee, Sara E; Boots, Bas; Cimarelli, Lucia; Guillebault, Delphine; Helmi, Karim; Marcheggiani, Stefania; Panaiotov, Stefan; Breitenbach, Ulrich; Akçaalan, Reyhan; Medlin, Linda K; Kittler, Katrin; Elliott, Christopher T; Campbell, Katrina

2016-05-01

Over the past few decades, there has been an increased frequency and duration of cyanobacterial Harmful Algal Blooms (HABs) in freshwater systems globally. These can produce secondary metabolites called cyanotoxins, many of which are hepatotoxins, raising concerns about repeated exposure through ingestion of contaminated drinking water or food or through recreational activities such as bathing/swimming. An ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) multi-toxin method has been developed and validated for freshwater cyanotoxins; microcystins-LR, -YR, -RR, -LA, -LY and -LF, nodularin, cylindrospermopsin, anatoxin-a and the marine diatom toxin domoic acid. Separation was achieved in around 9min and dual SPE was incorporated providing detection limits of between 0.3 and 5.6ng/L of original sample. Intra- and inter-day precision analysis showed relative standard deviations (RSD) of 1.2-9.6% and 1.3-12.0% respectively. The method was applied to the analysis of aquatic samples (n=206) from six European countries. The main class detected were the hepatotoxins; microcystin-YR (n=22), cylindrospermopsin (n=25), microcystin-RR (n=17), microcystin-LR (n=12), microcystin-LY (n=1), microcystin-LF (n=1) and nodularin (n=5). For microcystins, the levels detected ranged from 0.001 to 1.51μg/L, with two samples showing combined levels above the guideline set by the WHO of 1μg/L for microcystin-LR. Several samples presented with multiple toxins indicating the potential for synergistic effects and possibly enhanced toxicity. This is the first published pan European survey of freshwater bodies for multiple biotoxins, including two identified for the first time; cylindrospermopsin in Ireland and nodularin in Germany, presenting further incentives for improved monitoring and development of strategies to mitigate human exposure. Copyright © 2016 Elsevier B.V. All rights reserved.

[Simultaneous determination of daphnetin, daphnoretin, daphneticin in rat plasma by LC-MS/MS and its application in pharmacokinetic study].

PubMed

Hu, Yi-Yi-Li-Ge-Qi; Cao, Sa-Li; Lin, Long-Fei; Fu, Jing; Dong, Xiao-Xu; Yang, Chun-Jing; Zhang, Miao; Ni, Jian

2017-05-01

To establish HPLC-MS/MS method for simultaneous determination of daphnetin, daphnoretin, and daphneticin in rat plasma after oral and intravenous administration of Daphne giraldii extract, and then use them in the calculation of pharmacokinetic parameters. Six sprague-dawley rats received intragastric administration of D. giraldii extract (daphnetin, daphnoretin and daphneticin were 88.40, 3.24 and 4.28 mg•kg⁻¹, respectively). Their drug plasma concentration was determined by LC-MS/MS with schisandrin as an internal standard to draw plasma concentration-time curve. The pharmacokinetic parameters were calculated by Kinetica 4.4. The results showed that the linear range was 5-1 000 μg•L⁻¹ for daphnetin, daphnoretin and daphneticin, and the method ological test showed conformance to the requirements.The intraday and inter-day variable coefficients (RSD) were both less than 15.0%, indicating that both of legitimate precise and accuracy were consistent with the analysis requirements of biological samples. For daphnetin, the pharmacokinetic parameters Tmax, Cmax, AUC0-t, T1/2 and MRT were 4 h, 858.96 μg•L⁻¹, 10 566.4 μg•L⁻¹•h, 5.19 h and 9.43 h, respectively. For daphnoretin, the pharmacokinetic parameters Tmax, Cmax, AUC0-t, T1/2 and MRT were 2.92 h, 178.00 μg•L⁻¹, 905.89 μg•L⁻¹•h, 3.50 h and 6.95 h, respectively. For daphneticin, the pharmacokinetic parameters Tmax, Cmax, AUC0-t, T1/2 and MRT were 2 h, 36.67 μg•L⁻¹, 355.11 μg•L⁻¹•h, 4.95 h and 8.27 h, respectively. The LC-MS/MS analysis method established in this study was proved to be so accurate and sensitive that it can be applied to the pharmacokinetic study of daphnetin, daphnoretin and daphneticin. Copyright© by the Chinese Pharmaceutical Association.

Quantitation of free polyethylene glycol in PEGylated protein conjugate by size exclusion HPLC with refractive index (RI) detection.

PubMed

Li, Ning; Ziegemeier, Daisy; Bass, Laura; Wang, Wei

2008-12-15

In this study, size exclusion high performance liquid chromatography was evaluated for its application in separation and quantitation of free polyethylene glycol (PEG) and its PEGylated-protein-conjugate (PEG-conjugate). Although the large mass of the free PEG (2-fold greater than the protein) made separation difficult, chromatographic conditions were identified enabling resolution and quantitation of the free PEG, PEG-conjugate and non-PEGylated protein with Shodex Protein KW803 and KW804 columns in series and refractive index detection. The optimum resolution of 1.7 and 2.0 was achieved for the free PEG and PEG-conjugate as well as the free PEG and non-PEGylated protein using 20mM HEPES buffer at pH 6.5. Under this condition, the plot of log(10)MW of all the pertinent analytes against retention time showed a linear relationship with a correlation coefficient of 1. Limited assay performance evaluation demonstrated that the method was linear in the concentration range of 10 to 250 microg/mL of free PEG with correlation coefficients of > or = 0.99. When free PEG in this concentration range was spiked into PEG-conjugate samples at 1mg/mL, the recovery was in the range of 78%-120%. Detection and quantitation limits were determined to be, respectively, 10 and 25 microg/mL for free PEG. The R.S.D. for intra- and inter-day precision was 0.09% or less for retention time measurements and 2.9% or less for area count measurements. Robustness testing was performed by deliberately deviating +/-0.2 pH units away from the desired pH as well as by increasing the flow rate. These deviations resulted in no significant impact on area percent distribution of all species. However, separation was found to be sensitive to high ionic strength and buffer species.

LC–MS/MS determination of carbamathione in microdialysis samples from rat brain and plasma

PubMed Central

Kaul, Swetha; Williams, Todd D.; Lunte, Craig E.; Faiman, Morris D.

2009-01-01

A selective liquid chromatography–tandem mass spectrometric (LC–MS/MS) method was developed for the determination of S-(N, N-diethylcarbamoyl) glutathione (carbamathione) in microdialysis samples from rat brain and plasma. S-(N, N-Diethylcarbamoyl) glutathione (carbamathione) is a metabolite of disulfiram. This metabolite may be responsible for disulfiram’s effectiveness in the treatment of cocaine dependence. An analytical method using liquid chromatography–tandem mass spectrometric (LC–MS/MS) was developed to determine carbamathione in vivo using microdialysis sampling from rat brain and plasma. Chromatographic separations were carried out on an Alltech Altima C-18 (50 mm long × 2.1 mm i.d., 3 μm particles) analytical column at a flow rate of 0.3 ml/min. Solvent A consisted of 10 mM ammonium formate, methanol, and formic acid (99:1:0.06, v/v/v). Solvent B consisted of methanol, 10 mM ammonium formate and formic acid (99:1:0.06, v/v/v). A 20 min linear gradient from 95% aqueous to 95% organic was used. Tandem mass spectra were acquired on a Micromass Quattro Ultima “triple” quadrupole mass spectrometer equipped with an ESI interface. Quantitative mass spectrometric analysis was conducted in positive ion mode selected reaction monitoring (SRM) mode looking at the transition of m/z 407–100 and 175 for carbamathione and m/z 392–263 for the internal standard S-hexyl glutathione. The simultaneous collection of microdialysate from blood and brain was used to monitor carbamathione concentrations centrally and peripherally. Good linearity was obtained over a concentration range of 0.25–10,000 nM. The lowest limit of quantification (LLOQ) was determined to be 1 nM and the lowest limit of detection (LLOD) was calculated to be 0.25 nM. Intra- and inter-day accuracy and precision were determined and for all the samples evaluated, the variability was less that 10% (R.S.D.). PMID:19709836

Simultaneous determination of six bioactive saponins from Rhizoma Panacis Japonici in rat plasma by UHPLC-MS/MS: Application to a pharmacokinetic study.

PubMed

Zheng, Hong; Qiu, Feng; Zhao, Hui; Chen, Jie; Wang, Lei; Zou, Haiyan

2018-06-07

A specific, sensitive and rapid ultra high performance liquid chromatography-tandem mass spectrometric (UHPLC-MS/MS) method was developed and validated for simultaneous determination of six major bioactive constituents in Rhizoma Panacis Japonici (RPJ), including oleanolic acid-type chikusetsusaponin V, IV, hemsgiganoside B, damarane-type ginsenoside Rb1, Rg1 and Re in rat plasma, using estazolam as the internal standard (IS). Plasma samples were pretreated with methanol/acetonitrile (1:1, V/V) for protein precipitation. Chromatographic separation was performed on an Agilent Eclipse Plus C 18 column, using a gradient mobile phase consisting of methanol and 0.1% formic acid aqueous solution. A tandem mass spectrometric detection with an electrospray ionization (ESI) interface was conducted via multiple reaction monitoring (MRM) under positive ionization mode. For all the six analytes of interest, the calibration curves were linear in the concentration range of 2.00-500 ng/mL with r ≥ 0.9956. The intra- and inter-day precisions (in terms of relative standard deviation, RSD) were all below 10.2% and the accuracies (in terms of relative error, RE) were within -5.0% to 6.3% for all six analytes. Extraction recovery, matrix effect and stability data all met the acceptance criteria of FDA guideline for bioanalytical method validation. The developed method was applied to the pharmacokinetic study in rat. After oral administration of the total saponins from RPJ, six analytes were quickly absorbed into the blood and presented the phenomenon of double peaks. Among the six analytes, ginsenoside Rb1 showed slowest elimination from plasma with a t 1/2z of 16.00 h, while that of the others were between 1.72 and 5.62 h. In conclusion, the developed method was successfully used to simultaneously analyze major oleanolic acid-type and damarane-type saponins of RPJ in rat plasma after oral administration. Copyright © 2018. Published by Elsevier B.V.

Simultaneous determination of seven β-lactam antibiotics in human plasma for therapeutic drug monitoring and pharmacokinetic studies.

PubMed

Sime, Fekade Bruck; Roberts, Michael S; Roberts, Jason A; Robertson, Thomas A

2014-06-01

There is strong evidence in literature supporting the benefit of monitoring plasma concentrations of β-lactam antibiotics in the critically ill to ensure appropriateness of dosing. The objective of this work was to develop a method for the simultaneous determination of total concentrations piperacillin, benzylpenicillin, flucloxacillin, meropenem, ertapenem, cephazolin and ceftazidime in human plasma. Sample preparation involved protein precipitation with acetonitrile containing 0.1% formic acid and subsequent dilution of supernatant with 0.1% formic acid in water. Chromatographic separation was achieved on a reversed phase column (C18, 2.6 μm, 2.1 × 50 mm) via gradient elution using water and acetonitrile, each containing 0.1% formic acid, as mobile phase. Tandem mass spectrometry (MSMS) analysis was performed, after electrospray ionization in the positive mode, with multiple reaction monitoring (MRM). The method is accurate with the inter-day and intra-day accuracies of quality control samples (QCs) ranging from 95 to 107% and 95 to 108%, respectively. It is also precise with intra-day and inter-day coefficient of variations ranging from 4 to 12% and 5 to 14%, respectively. The lower limit of quantification was 0.1 μg/mL for each antibiotic except flucloxacillin (0.25 μg/mL). Recovery was greater than 96% for all analytes except for ertapenem (78%). Coefficients of variation for the matrix effect were less than 10% over the six batches of plasma. Analytes were stable over three freeze-thaw cycles, and for reasonable hours on the bench top as well as post-preparation. This novel liquid chromatography tandem mass spectrometry method proved accurate, precise and applicable for therapeutic drug monitoring and pharmacokinetic studies of the selected β-lactam antibiotics. Copyright © 2014 Elsevier B.V. All rights reserved.

Ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction for the simultaneous determination of 12 new antidepressants and 2 antipsychotics in whole blood by gas chromatography-mass spectrometry.

PubMed

Chen, Xiujuan; Zheng, Shuiqing; Le, Jian; Qian, Zheyuan; Zhang, Runsheng; Hong, Zhanying; Chai, Yifeng

2017-08-05

Antidepressant drugs are widely used in the treatment of different psychiatric disorders, as well as in conjunction with antipsychotics for the treatment of major depressive disorder. In this study, a simple and rapid ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) method was developed for the simultaneous determination of 12 new antidepressants (norfluoxetine, fluoxetine, fluvoxamine, agomelatine, mirtazapine, moclobemide, melitracen, N-desmethylmirtazapine, maprotiline, sertraline, citalopram, paroxetine) and 2 antipsychotics (clozapine and haloperidol) in human whole blood by gas chromatography-mass spectrometry (GC-MS). Different parameters affecting the UA-LDS-DLLME were optimized and the optimal conditions were as follows: 100μL of toluene as extraction solvent, extraction pH 12 and 3min of ultrasound stirring. Good linearity (R 2 ≥0.991) was obtained at the concentration range of 15-1500ng/mL for norfluoxetine, fluoxetine, fluvoxamine, melitracen, maprotiline and citalopram, and 5-500ng/mL for agomelatine, mirtazapine, moclobemide, N-desmethylmirtazapine, sertraline, paroxetine, clozapine and haloperidol. The intra-day and inter-day precision were all less than 10%, and accuracy of intra-day and inter-day were in the range of -12.7% to 7.9% and -13.9 to 11.8%, respectively. The extraction recoveries of most analytes were more than 60%. The UA-LDS-DLLME/GC-MS method was demonstrated with acceptable precision, accuracy and good specificity for the simultaneous determination of 12 antidepressants and 2 antipsychotics, and has been successfully applied in a real case. Copyright © 2017 Elsevier B.V. All rights reserved.

Combined derivatization and high-performance liquid chromatography with fluorescence and ultraviolet detection for simultaneous analysis of octreotide and gabexate mesylate metabolite in human pancreatic juice samples.

PubMed

Carlucci, Giuseppe; Selvaggi, Federico; Sulpizio, Sara; Bassi, Claudio; Carlucci, Maura; Cotellese, Roberto; Ferrone, Vincenzo; Innocenti, Paolo; Locatelli, Marcello

2015-06-01

A simple and sensitive method based on the combination of derivatization and high-performance liquid chromatography with ultraviolet and fluorimetric detection was developed for the simultaneous determination of octreotide and gabexate mesylate metabolite in human pancreatic juice samples. Parameters of the derivatization procedure affecting extraction efficiency were optimized. The developed method was validated according to the International Conference on Harmonization guidelines. The calibration curves were linear over a range of 0.1-15 µg/mL for octreotide and 0.20-15 µg/mL for gabexate mesylate metabolite. Derivatized products of octreotide and gabexate mesylate metabolite were separated on a Luna C18 column (4.6 × 250 mm; 5 µm particle size) using a gradient with a run time of 36 min, without further purification. The limits of detection were 0.025 and 0.05, respectively, for octreotide and gabexate mesylate metabolite. This paper reports the validation of a quantitative high performance liquid chromatography-photodiode array-fluorescence (HPLC-PDA-FL) method for the simultaneous analysis of octreotide and gabexate mesylate metabolite in pancreatic juice by protein precipitation using zinc sulfate-methanol-acetonitrile containing the derivatizing reagent, 4-fluoro-7-nitro-[2,1,3]-benzoxadiazole (NBD-F). Derivatized products of octreotide and gabexate mesylate metabolite were separated on a Luna C18 column (4.6 × 250 mm; 5 µm particle size) using a gradient with a run time of 36 min, without further purification. The method was validated over the concentration ranges 0.1-15 and 0.2-15 µg/mL for octreotide and gabexate mesylate metabolite, respectively, in human pancreatic juice. Biphalin and methyl-p-hydroxybenzoate were used as the internal standards. This method was successfully utilized to support clinical studies in humans. The results from assay validations show that the method is selective, sensitive and robust. The limit of quantification of the method was 0.1 µg/mL for octreotide and 0.2 µg/mL for gabexate mesylate metabolite, and matrix matched standard curves showed a good linearity up to 15 µg/mL. In the entire analytical range the intra- and inter-day precision (RSD%) values were respectively ≤5.9% and ≤3.1% for octreotide and ≤2.0% and ≤3.9% for gabexate mesylate metabolite. For both analytes the intra- and inter-day accuracy (bias) values ranged respectively from -6.8 to -2.5% and from -4.6 to -5.7%. This method utilizes derivatization with NBD-F and provides adequate sensitivity for both drugs. Copyright © 2014 John Wiley & Sons, Ltd.

Solid-phase extraction combined with dispersive liquid-liquid microextraction and chiral liquid chromatography-tandem mass spectrometry for the simultaneous enantioselective determination of representative proton-pump inhibitors in water samples.

PubMed

Zhao, Pengfei; Deng, Miaoduo; Huang, Peiting; Yu, Jia; Guo, Xingjie; Zhao, Longshan

2016-09-01

This report describes, for the first time, the simultaneous enantioselective determination of proton-pump inhibitors (PPIs-omeprazole, lansoprazole, pantoprazole, and rabeprazole) in environmental water matrices based on solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME) and chiral liquid chromatography-tandem mass spectrometry. The optimized results of SPE-DLLME were obtained with PEP-2 column using methanol-acetonitrile (1/1, v/v) as elution solvent, dichloroethane, and acetonitrile as extractant and disperser solvent, respectively. The separation and determination were performed using reversed-phase chromatography on a cellulose chiral stationary phase, a Chiralpak IC (250 mm × 4.6 mm, 5 μm) column, under isocratic conditions at 0.6 mL min(-1) flow rate. The analytes were detected in multiple reaction monitoring (MRM) mode by triple quadrupole mass spectrometry. Isotopically labeled internal standards were used to compensate matrix interferences. The method provided enrichment factors of around 500. Under optimal conditions, the mean recoveries for all eight enantiomers from the water samples were 89.3-107.3 % with 0.9-10.3 % intra-day RSD and 2.3-8.1 % inter-day RSD at 20 and 100 ng L(-1) levels. Correlation coefficients (r (2)) ≥ 0.999 were achieved for all enantiomers within the range of 2-500 μg L(-1). The method detection and quantification limits were at very low levels, within the range of 0.67-2.29 ng L(-1) and 2.54-8.68 ng L(-1), respectively. This method was successfully applied to the determination of the concentrations and enantiomeric fractions of the targeted analytes in wastewater and river water, making it applicable to the assessment of the enantiomeric fate of PPIs in the environment. Graphical Abstract Simultaneous enantioselective determination of representative proton-pump inhibitors in water samples.

Simultaneous Determination of Eight Bioactive Compounds in Dianthus superbus by High-performance Liquid Chromatography

PubMed Central

Yun, Bo-Ra; Yang, Hye Jin; Weon, Jin Bae; Lee, Jiwoo; Eom, Min Rye; Ma, Choong Je

2016-01-01

Background: Dianthus superbus, one of traditional herbal medicine, is widely used to treat urethritis, carbuncles and carcinoma. Objective: A simultaneous determination method was established for controlling the quality of D. superbus using the eight compounds, (E)-methyl-4-hydroxy-4-(8a-methyl-3-oxodecahydronaphthalen-4a-yl) (1), diosmetin-7-O(2'',6''-di-O-α-L-rhamnopyranosyl)-β-D-glucopyranoside (2), vanillic acid (3), 4-hydroxyphenyl acetic acid (4), 4-methoxyphenyl acetic acid (5), (E)-4-methoxycinnamic acid (6), 3-methoxy-4-hydroxyphenylethanol (7), and methyl hydroferulate (8) isolated from D. superbus. Materials and Methods: This analysis method was developed using high performance liquid chromatography coupled with diode array detector with a Shishedo C18 column at a column temperature of 3°C. The mobile phase was composed of 0.1% trifluoroacetic acid in water and acetonitrile. The flow rate was 1 ml/min and detection wavelength was set at 205 nm and 280 nm. Validation was performed in order to demonstrate selectivity, accuracy and precision of the method. Results: The calibration curves showed good linearity (R2 > 0.99). The limits of detection and limits of quantification were within the ranges 0.0159–0.6205 μg/ml and 0.3210–1.8802 μg/ml, respectively. Moreover, the relative standard deviations of intra- and inter-day precision were both <2.98%. The overall recoveries were in the range of 96.23–109.87%. Quantitative analysis of eight compounds in 12 D. superbus samples (D-1–D-12) from various regions were analyzed and compared by developed method. Conclusion: As a result, this established method was accurate and sensitive for the quality evaluation of eight compounds isolated from D. superbus and may provide a new basis for quality control of D. superbus. SUMMARY A simultaneous determination method of eight compounds in Dianthus superbus was established by high performance liquid chromatography-diode array detectorDeveloped analysis method is validated with linearity, precious and accuracyThe newly established method was successfully evaluated contents of eight compounds in 12 D. superbus samples (D.1.D.12) from various regions and compared. Abbreviations used: HPLC: High performance liquid chromatography, LOD: Limits of detection, LOQ: Limits of quantification, RSD: Relative standard deviation. PMID:27279718

Simultaneous Determination of Eight Bioactive Compounds in Dianthus superbus by High-performance Liquid Chromatography.

PubMed

Yun, Bo-Ra; Yang, Hye Jin; Weon, Jin Bae; Lee, Jiwoo; Eom, Min Rye; Ma, Choong Je

2016-05-01

Dianthus superbus, one of traditional herbal medicine, is widely used to treat urethritis, carbuncles and carcinoma. A simultaneous determination method was established for controlling the quality of D. superbus using the eight compounds, (E)-methyl-4-hydroxy-4-(8a-methyl-3-oxodecahydronaphthalen-4a-yl) (1), diosmetin-7-O(2'',6''-di-O-α-L-rhamnopyranosyl)-β-D-glucopyranoside (2), vanillic acid (3), 4-hydroxyphenyl acetic acid (4), 4-methoxyphenyl acetic acid (5), (E)-4-methoxycinnamic acid (6), 3-methoxy-4-hydroxyphenylethanol (7), and methyl hydroferulate (8) isolated from D. superbus. This analysis method was developed using high performance liquid chromatography coupled with diode array detector with a Shishedo C18 column at a column temperature of 3°C. The mobile phase was composed of 0.1% trifluoroacetic acid in water and acetonitrile. The flow rate was 1 ml/min and detection wavelength was set at 205 nm and 280 nm. Validation was performed in order to demonstrate selectivity, accuracy and precision of the method. The calibration curves showed good linearity (R (2) > 0.99). The limits of detection and limits of quantification were within the ranges 0.0159-0.6205 μg/ml and 0.3210-1.8802 μg/ml, respectively. Moreover, the relative standard deviations of intra- and inter-day precision were both <2.98%. The overall recoveries were in the range of 96.23-109.87%. Quantitative analysis of eight compounds in 12 D. superbus samples (D-1-D-12) from various regions were analyzed and compared by developed method. As a result, this established method was accurate and sensitive for the quality evaluation of eight compounds isolated from D. superbus and may provide a new basis for quality control of D. superbus. A simultaneous determination method of eight compounds in Dianthus superbus was established by high performance liquid chromatography-diode array detectorDeveloped analysis method is validated with linearity, precious and accuracyThe newly established method was successfully evaluated contents of eight compounds in 12 D. superbus samples (D.1.D.12) from various regions and compared. Abbreviations used: HPLC: High performance liquid chromatography, LOD: Limits of detection, LOQ: Limits of quantification, RSD: Relative standard deviation.

Automated and sensitive method for the determination of formoterol in human plasma by high-performance liquid chromatography and electrochemical detection.

PubMed

Campestrini, J; Lecaillon, J B; Godbillon, J

1997-12-19

An automated high-performance liquid chromatography (HPLC) method for the determination of formoterol in human plasma with improved sensitivity has been developed and validated. Formoterol and CGP 47086, the internal standard, were extracted from plasma (1 ml) using a cation-exchange solid-phase extraction (SPE) cartridge. The compounds were eluted with pH 6 buffer solution-methanol (70:30, v/v) and the eluate was further diluted with water. An aliquot of the extract solution was injected and analyzed by HPLC. The extraction, dilution, injection and chromatographic analysis were combined and automated using the automate (ASPEC) system. The chromatographic separations were achieved on a 5 microm, Hypersil ODS analytical column (200 mm x 3 mm I.D.), using (pH 6 phosphate buffer, 0.035 M + 20 mg/l EDTA)-MeOH-CH3CN (70:25:5, v/v/v) as the mobile phase at a flow-rate of 0.4 ml/min. The analytes were detected with electrochemical detection at an operating potential of +0.63 V. Intra-day accuracy and precision were assessed from the relative recoveries of calibration/quality control plasma samples in the concentration range of 7.14 to 238 pmol/l of formoterol base. The accuracy over the entire concentration range varied from 81 to 105%, and the precision (C.V.) ranged from 3 to 14%. Inter-day accuracy and precision were assessed in the concentration range of 11.9 to 238 pmol/l of formoterol base in plasma. The accuracy over the entire concentration range varied from 98 to 109%, and precision ranged from 8 to 19%. At the limit of quantitation (LOQ) of 11.9 pmol/l for inter-day measurements, the recovery value was 109% and C.V. was 19%. As shown from intra-day accuracy and precision results, favorable conditions (a newly used column, a newly washed detector cell and moderate residual cell current level) allowed us to reach a LOQ of 7.14 pmol/l of formoterol base (3 pg/ml of formoterol fumarate dihydrate). Improvement of the limit of detection by a factor of about 10 was reached as compared to the previously described methods. The method has been applied for quantifying formoterol in plasma after 120 microg drug inhalation to volunteers. Formoterol was still measurable at 24 h post-dosing in most subjects and a slow elimination of formoterol from plasma beyond 6-8 h after inhalation was demonstrated for the first time thanks to the sensitivity of the method.

Quantitative determination of rosuvastatin in human plasma by liquid chromatography with electrospray ionization tandem mass spectrometry.

PubMed

Xu, Dong-Hang; Ruan, Zou-Rong; Zhou, Quan; Yuan, Hong; Jiang, Bo

2006-01-01

A simple and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for determining rosuvastatin in human plasma, a new synthetic hydroxymethylglutaryl-coenzyme A reductase inhibitor. The analyte and internal standard (IS; cilostazol) were extracted by simple one-step liquid/liquid extraction with ether. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40 degrees C. The chromatographic separation was performed on an Atlantis C18 column (2.1 mm x 150 mm, 5.0 microm) with a mobile phase consisting of 0.2% formic acid/methanol (30:70, v/v) at a flow rate of 0.20 mL/min. The analyses were carried out by multiple reaction monitoring (MRM) using the precursor-to-product combinations of m/z 482 --> 258 and m/z 370 --> 288. The areas of peaks from the analyte and the IS were used for quantification of rosuvastatin. The method was validated according to the FDA guidelines on bioanalytical method validation. Validation results indicated that the lower limit of quantification (LLOQ) was 0.2 ng/mL and the assay exhibited a linear range of 0.2-50.0 ng/mL and gave a correlation coefficient (r) of 0.9991 or better. Quality control samples (0.4, 8, 25 and 40 ng/mL) in six replicates from three different runs of analysis demonstrated an intra-assay precision (RSD) 7.97-15.94%, an inter-assay precision 3.19-15.27%, and an overall accuracy (relative error) of < 3.7%. The method can be applied to pharmacokinetic or bioequivalence studies of rosuvastatin.

On-line solid phase extraction using the Prospekt-2 coupled with a liquid chromatography/tandem mass spectrometer for the determination of dextromethorphan, dextrorphan and guaifenesin in human plasma.

PubMed

Kuhlenbeck, Debbie L; Eichold, Thomas H; Hoke, Steven H; Baker, Timothy R; Mensen, Robert; Wehmeyer, Kenneth R

2005-01-01

An on-line liquid chromatography/tandem mass spectrometry (LC-MS/MS) procedure, using the Prospekt- 2 system, was developed and used for the determination of the levels of the active ingredients of cough/cold medications in human plasma matrix. The experimental configuration allows direct plasma injection by performing on- line solid phase extraction (SPE) on small cartridge columns prior to elution of the analyte(s) onto the analytical column and subsequent MS/MS detection. The quantitative analysis of three analytes with differing polarities, dextromethorphan (DEX), dextrorphan (DET) and guaifenesin (GG) in human plasma presented a significant challenge. Using stable-isotope-labeled internal standards for each analyte, the Prospekt-2 on-line methodology was evaluated for sensitivity, suppression, accuracy, precision, linearity, analyst time, analysis time, cost, carryover and ease of use. The lower limit of quantitation for the on-line SPE procedure for DEX, DET and GG was 0.05, 0.05 and 5.0 ng mL(-1), respectively, using a 0.1 mL sample volume. The linear range for DEX and DET was 0.05-50 ng mL(-1) and was 5-5,000 ng mL(-1) for GG. Accuracy and precision data for five different levels of QC samples were collected over three separate days. Accuracy ranged from 90% to 112% for all three analytes, while the precision, as measured by the %RSD, ranged from 1.5% to 16.0%

Determination of 13C isotopic enrichment of valine and threonine by GC-C-IRMS after formation of the N(O,S)-ethoxycarbonyl ethyl ester derivatives of the amino acids.

PubMed

Godin, Jean-Philippe; Faure, Magali; Breuille, Denis; Hopfgartner, Gérard; Fay, Laurent-Bernard

2007-06-01

We describe a new method of assessing, in a single run, (13)C isotopic enrichment of both Val and Thr by gas chromatography-combustion-isotope-ratio mass spectrometry (GC-C-IRMS). This method characterised by a rapid one-step derivatisation procedure performed at room temperature to form the N(O,S)-ethoxycarbonyl ethyl ester derivatives, and a polar column for GC. The suitability of this method for Val and Thr in in-vivo samples (mucosal hydrolysate) was demonstrated by studying protein metabolism with two tracers ((13)C-valine or (13)C-threonine). The intra-day and inter-day repeatability were both assessed either with standards or with in-vivo samples at natural abundance and at low (13)C isotopic enrichment. For inter-day repeatability CVs were between 0.8 and 1.5% at natural abundance and lower than 5.5% at 0.112 and 0.190 atom% enrichment for Val and Thr, respectively. Overall isotopic precision was studied for eleven standard amino acid derivatives (those of Val, Ala, Leu, Iso, Gly, Pro, Asp, Thr, Ser, Met, and Phe) and was assessed at 0.32 per thousand. The (13)C isotopic measurement was then extended to the other amino acids (Ala, Val, Leu, Iso, Gly, Pro, Thr, and Phe) at natural abundance for in-vivo samples. The isotopic precision was better than 0.002 atom% per amino acid (for n = 4 rats). This analytical method was finally applied to an animal study to measure Thr utilization in protein synthesis.

Determination of patulin in commercial apple juice by micellar electrokinetic chromatography.

PubMed

Murillo, M; González-Peñas, E; Amézqueta, S

2008-01-01

A novel and validated micellar electrokinetic capillary chromatography (MEKC) method using ultraviolet detection (UV) has been applied to the quantitative analysis of patulin (PAT) in commercial apple juice. Patulin was extracted from samples with an ethylacetate solution. The micellar electrokinetic capillary chromatography (MECK) parameters studied for method optimization were buffer composition, voltage, temperature, and a separation between PAT and 5-hydroxymethylfurfural (HMF) (main interference in apple juice PAT analysis) peaks until reaching baseline. The method passes a series of validation tests including selectivity, linearity, limit of detection and quantification (0.7 and 2.5 microgL(-1), respectively), precision (within and between-day variability) and recovery (80.2% RSD=4%), accuracy, and robustness. This method was successfully applied to the measurement of 20 apple juice samples obtained from different supermarkets. One hundred percent of the samples were contaminated with a level greater than the limit of detection, with mean and median values of 41.3 and 35.7 microgL(-1), respectively.

A portable analyser for the measurement of ammonium in marine waters.

PubMed

Amornthammarong, Natchanon; Zhang, Jia-Zhong; Ortner, Peter B; Stamates, Jack; Shoemaker, Michael; Kindel, Michael W

2013-03-01

A portable ammonium analyser was developed and used to measure in situ ammonium in the marine environment. The analyser incorporates an improved LED photodiode-based fluorescence detector (LPFD). This system is more sensitive and considerably smaller than previous systems and incorporates a pre-filtering subsystem enabling measurements in turbid, sediment-laden waters. Over the typical range for ammonium in marine waters (0–10 mM), the response is linear (r(2) = 0.9930) with a limit of detection (S/N ratio > 3) of 10 nM. The working range for marine waters is 0.05–10 mM. Repeatability is 0.3% (n =10) at an ammonium level of 2 mM. Results from automated operation in 15 min cycles over 16 days had good overall precision (RSD = 3%, n = 660). The system was field tested at three shallow South Florida sites. Diurnal cycles and possibly a tidal influence were expressed in the concentration variability observed.

Analysis of tacrolimus and creatinine from a single dried blood spot using liquid chromatography tandem mass spectrometry.

PubMed

Koop, Dennis R; Bleyle, Lisa A; Munar, Myrna; Cherala, Ganesh; Al-Uzri, Amira

2013-05-01

Long term therapeutic drug monitoring and assessment of renal function are required in renal transplant recipients on immunosuppressant therapy such as tacrolimus. Dry blood spots (DBS) have been used successfully in the clinic for many years and offers a convenient, simple and non-invasive method for repeated blood tests. We developed and performed a preliminary validation of a method for the analysis of tacrolimus and creatinine from a single DBS using liquid chromatography-tandem mass spectrometric (LC-MS/MS). Tacrolimus and creatinine were extracted from a 6mm punch with a mixture of methanol/acetonitrile containing ascomycin and deuterated creatinine as internal standards. A 10 μl aliquot of the extract was analyzed directly after dilution for creatinine with normal phase high performance liquid chromatography and multiple reaction monitoring. The remainder of the extract was processed and analyzed for tacrolimus. The lower limit of quantification for tacrolimus was 1 ng/ml with accuracy of 0.34% bias and precision (CV) of 11.1%. The precision ranged from 1.33% to 7.68% and accuracy from -4.44% to 11.6% bias for the intra- and inter-day analysis. The lower limit of quantification of creatinine was 0.01 mg/dL with precision of 7.94%. Accuracy was based on recovery of additional creatinine spiked into whole blood samples and ranged from -2.45% bias at 5 mg/dL to 3.75% bias at 0.5 mg/dL. Intra- and inter-day precision was from 3.48 to 4.11%. The assay was further validated with DBS prepared from pediatric renal transplant recipients. There was excellent correlation between the levels of tacrolimus and creatinine obtained from the clinical laboratory and the DBS method developed. After additional validation, this assay may have a significant impact on compliance with medication intake as well as potentially lowering the cost associated with intravenous blood draws in clinical laboratories. Copyright © 2013 Elsevier B.V. All rights reserved.

Development and validation of a new method to simultaneously quantify triazoles in plasma spotted on dry sample spot devices and analysed by HPLC-MS.

PubMed

Baietto, Lorena; D'Avolio, Antonio; Marra, Cristina; Simiele, Marco; Cusato, Jessica; Pace, Simone; Ariaudo, Alessandra; De Rosa, Francesco Giuseppe; Di Perri, Giovanni

2012-11-01

Therapeutic drug monitoring (TDM) of triazoles is widely used in clinical practice to optimize therapy. TDM is limited by technical problems and cost considerations, such as sample storage and dry-ice shipping. We aimed to develop and validate a new method to analyse itraconazole, posaconazole and voriconazole in plasma spotted on dry sample spot devices (DSSDs) and to quantify them by an HPLC system. Extraction from DSSDs was done using n-hexane/ethyl acetate and ammonia solution. Samples were analysed using HPLC with mass spectrometry (HPLC-MS). Accuracy and precision were assayed by inter- and intra-day validation. The stability of triazoles in plasma spotted on DSSDs was investigated at room temperature for 1 month. The method was compared with a validated standard HPLC method for quantification of triazoles in human plasma. Mean inter- and intra-day accuracy and precision were <15% for all compounds. Triazoles were stable for 2 weeks at room temperature. The method was linear (r(2) > 0.999) in the range 0.031-8 mg/L for itraconazole and posaconazole, and 0.058-15 mg/L for voriconazole. High sensitivity was observed; limits of detection were 0.008, 0.004 and 0.007 mg/L for itraconazole, posaconazole and voriconazole, respectively. A high degree of correlation (r(2) > 0.94) was obtained between the DSSD method and the standard method of analysis. The method that we developed and validated to quantify triazoles in human plasma spotted on DSSDs is accurate and precise. It overcomes problems related to plasma sample storage and shipment, allowing TDM to be performed in a cheaper and safer manner.

A simple method using two-step hot embossing technique with shrinking for fabrication of cross microchannels on PMMA substrate and its application to electrophoretic separation of amino acids in functional drinks.

PubMed

Wiriyakun, Natta; Nacapricha, Duangjai; Chantiwas, Rattikan

2016-12-01

This work presents a simple hot embossing method with a shrinking procedure to produce cross-shape microchannels on poly(methyl methacrylate) (PMMA) substrate for the fabrication of an electrophoresis chip. The proposed method employed a simple two-step hot embossing technique, carried out consecutively on the same piece of substrate to make the crossing channels. Studies of embossing conditions, i.e. temperature, pressure and time, were carried out to investigate their effects on the dimension of the microchannels. Applying a simple shrinking procedure reduced the size of the channels from 700±20µm wide×150±5µm deep to 250±10µm wide×30±2µm deep, i.e. 80% and 64% reduction in the depth and width, respectively. Thermal fusion was employed to bond the PMMA substrate with a PMMA cover plate to produce the microfluidic device. Replication of microchip was achieved by precise control of conditions in the fabrication process (pressure, temperature and time), resulting in lower than 7% RSD of channel dimension, width and depth (n =10 devices). The method was simple and robust without the use of expensive equipment to construct the microstructure on a thermoplastic substrate. The PMMA microchip was used for demonstration of amine functionalization on the PMMA surface, measurement of electroosmotic flow and for electrophoretic separation of amino acids in functional drink samples. The precision of migration time and peak area of the amino acids, Lys, Ile and Phe at 125μM to 500μM, were in the range 3.2-4.2% RSD (n=9 devices) and 4.5-5.3% RSD (n=9 devices), respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Rapid analysis of cyclamate in foods and beverages by gas chromatography-electron capture detector (GC-ECD).

PubMed

Yu, Shengbing; Zhu, Binghui; Lv, Fen; Li, Shaoxiao; Huang, Weixiong

2012-10-15

A rapid method for determination of sodium cyclamate in foods and beverages was developed. Sodium cyclamate was converted to N,N-dichloridecyclohexylamine by reaction with sodium hypochlorite under acid condition. N,N-dichloridecyclohexylamine was subsequently extracted by n-hexane and determined by gas chromatography. Conditions such as derivatization time, the concentration of sodium hypochlorite and sulphuric acid were optimised. Amino acids, aliphatic amines, and food additives such as preservatives, dyes and sweeteners showed no interference for quantification of cyclamate. The correlation coefficient of calibration curve was 0.9993 in the range of 5.0-250mg/L. The limits of detection (LOD) and limits of quantification (LOQ) were calculated as three or ten times the signal-to-noise ratio (S/N), respectively. The LOD and LOQ for yellow wine and fruit juice were 0.05 and 0.2mg/L, respectively. The LOD and LOQ for cake and preserved fruit were 0.25 and 0.8mg/kg, respectively. The intra-day and inter-day RSD were 0.28% and 1.1% (n=5), respectively. The method was successfully applied for determination of cyclamate in yellow wine, cake, fruit juice and preserved fruit. This method was simple, fast, and sensitive. It was suitable for the determination of cyclamate in foods and beverages for safety and quality control inspections. Copyright © 2012 Elsevier Ltd. All rights reserved.

Development and optimization of a reversed-phase high-performance liquid chromatographic method for the determination of acetaminophen and its major metabolites in rabbit plasma and urine after a toxic dose.

PubMed

Vertzoni, M V; Archontaki, H A; Galanopoulou, P

2003-07-14

A reversed-phase high-performance liquid chromatographic method with detection at 242 nm was developed, optimized and validated for the determination of acetaminophen (A) and its major metabolites glucuronide (AG) and sulfate (AS) conjugates in rabbit plasma and urine after a toxic dose. m-Aminophenol was used as internal standard (IS). A Hypersil BDS RP-C18 column (250 x 4.6 mm), 5 microm particle size, was equilibrated with a mobile phase composed of aqueous buffer solution of KH2PO4 0.05 M containing 1% CH3COOH (pH 6.5) and methanol (95:5, v/v). Its flow rate was 1.5 ml/min. Calibration curves of A, AG and AS were linear in the concentration ranges of 0.5-250, 1-200, 0.5-100 microg/ml in plasma and 1-200, 0.5-150, 0.5-100 microg/ml in urine matrix, respectively. Limits of detection and quantitation were calculated in all cases and extensive recovery studies were also performed. Intra-day relative standard deviation (R.S.D.) for A, AG and AS in plasma was less than 5, 4, 2% and in urine less than 4, 7, 4%, respectively, while the corresponding inter-day values were 7, 6, 4% and 5, 8, 6%, respectively.

Electroplating of nanostructured polyaniline-polypyrrole composite coating in a stainless-steel tube for on-line in-tube solid phase microextraction.

PubMed

Asiabi, Hamid; Yamini, Yadollah; Seidi, Shahram; Esrafili, Ali; Rezaei, Fatemeh

2015-06-05

In this work, a novel and efficient on-line in-tube solid phase microextraction method followed by high performance liquid chromatography was developed for preconcentration and determination of trace amounts of parabens. A nanostructured polyaniline-polypyrrole composite was electrochemically deposited on the inner surface of a stainless steel tube and used as the extraction phase. Several important factors that influence the extraction efficiency, including type of solid-phase coating, extraction and desorption times, flow rates of the sample solution and eluent, pH, and ionic strength of the sample solution were investigated and optimized. Under the optimal conditions, the limits of detection were in the range of 0.02-0.04 μg L(-1). This method showed good linearity for parabens in the range of 0.07-50 μg L(-1), with coefficients of determination better than 0.998. The intra- and inter-assay precisions (RSD%, n=3) were in the range of 5.9-7.0% and 4.4-5.7% at three concentration levels of 2, 10, and 20 μg L(-1), respectively. The extraction recovery values for the spiked samples were in the acceptable range of 80.3-90.2%. The validated method was successfully applied for analysis of methyl-, ethyl-, and propyl parabens in some water, milk, and juice samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous determination of acetaminophen and dihydrocodeine in human plasma by UPLC-MS/MS: Its pharmacokinetic application.

PubMed

Qiu, Xiangjun; Lou, Dan; Su, Ding; Liu, Zebin; Gao, Pengtao; Zhang, Nan-sheng

2015-06-15

An ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to determine acetaminophen (AAP) and dihydrocodeine (DHC) in human plasma simultaneously. Plasma samples were prepared using protein precipitation with acetonitrile, the two analytes and the internal standard midazolam were separated on an Acquity UPLC BEH C18 column and mass spectrometric analysis was performed using a QTrap5500 mass spectrometer coupled with an electro-spray ionization (ESI) source in the positive ion mode. The MRM transitions of m/z 151.2→110.0 and m/z 302.3→199.2 were used to quantify for AAP and DHC, respectively. The linearity of this method was found to be within the concentration range of 50-10000ng/mL for AAP, and 1-100ng/mL for DHC in human plasma, respectively. The lower limit of quantification (LLOQ) was 50ng/mL and 1ng/mL for AAP and DHC in human plasma, respectively. The relative standard deviations (RSD) of intra and inter precision were less than 10% for both AAP and DHC. The analysis time of per sample was 1.0min. The developed and validated method was successfully applied to a pharmacokinetic study of AAP (500mg) with DHC (20mg) capsule in Chinese healthy volunteers (N=20). Copyright © 2015 Elsevier B.V. All rights reserved.

Direct lead isotope analysis in Hg-rich sulfides by LA-MC-ICP-MS with a gas exchange device and matrix-matched calibration.

PubMed

Zhang, Wen; Hu, Zhaochu; Günther, Detlef; Liu, Yongsheng; Ling, Wenli; Zong, Keqing; Chen, Haihong; Gao, Shan

2016-12-15

In situ Pb isotope data of sulfide samples measured by LA-MC-ICP-MS provide valuable geochemical information for studies of the origin and evolution of ore deposits. However, the severe isobaric interference of 204 Hg on 204 Pb and the lack of matrix-matched sulfide reference materials limit the precision of Pb isotopic analyses for Hg-rich sulfides. In this study, we observe that Hg forms vapor and can be completely removed from sample aerosol particles produced by laser ablation using a gas exchange device. Additionally, this device does not influence the signal intensities of Pb isotopes. The within-run precision, the external reproducibility and the analytical accuracy are significantly improved for the Hg-rich sulfide samples using this mercury-vapor-removing device. Matrix effects are observed when using silicate glass reference materials as the external standards to assess the relationship of mass fractionation factors between Tl and Pb in sulfide samples, resulting in a maximum deviation of ∼0.20% for 20x Pb/ 204 Pb. Matrix-matched reference materials are therefore required for the highly precise and accurate Pb isotope analyses of sulfide samples. We investigated two sulfide samples, MASS-1 (the Unites States Geological Survey reference materials) and Sph-HYLM (a natural sphalerite), as potential candidates. Repeated analyses of the two proposed sulfide reference materials by LA-MC-ICP-MS yield good external reproducibility of <0.04% (RSD, k = 2) for 20x Pb/ 206 Pb and <0.06% (RSD, k = 2) for 20x Pb/ 204 Pb with the exception of 20x Pb/ 204 Pb in MASS-1, which provided an external reproducibility of 0.24% (RSD, k = 2). Because the concentration of Pb in MASS-1 (76 μg g -1 ) is ∼5.2 times lower than that in Sph-HYLM (394 ± 264 μg g -1 ). The in situ analytical results of MASS-1 and Sph-HYLM are consistent with the values obtained by solution MC-ICP-MS, demonstrating the reliability and robustness of our analytical protocol. Copyright © 2016 Elsevier B.V. All rights reserved.

Sonographic estimation of fetal weight: comparison of bias, precision and consistency using 12 different formulae.

PubMed

Anderson, N G; Jolley, I J; Wells, J E

2007-08-01

To determine the major sources of error in ultrasonographic assessment of fetal weight and whether they have changed over the last decade. We performed a prospective observational study in 1991 and again in 2000 of a mixed-risk pregnancy population, estimating fetal weight within 7 days of delivery. In 1991, the Rose and McCallum formula was used for 72 deliveries. Inter- and intraobserver agreement was assessed within this group. Bland-Altman measures of agreement from log data were calculated as ratios. We repeated the study in 2000 in 208 consecutive deliveries, comparing predicted and actual weights for 12 published equations using Bland-Altman and percentage error methods. We compared bias (mean percentage error), precision (SD percentage error), and their consistency across the weight ranges. 95% limits of agreement ranged from - 4.4% to + 3.3% for inter- and intraobserver estimates, but were - 18.0% to 24.0% for estimated and actual birth weight. There was no improvement in accuracy between 1991 and 2000. In 2000 only six of the 12 published formulae had overall bias within 7% and precision within 15%. There was greater bias and poorer precision in nearly all equations if the birth weight was < 1,000 g. Observer error is a relatively minor component of the error in estimating fetal weight; error due to the equation is a larger source of error. Improvements in ultrasound technology have not improved the accuracy of estimating fetal weight. Comparison of methods of estimating fetal weight requires statistical methods that can separate out bias, precision and consistency. Estimating fetal weight in the very low birth weight infant is subject to much greater error than it is in larger babies. Copyright (c) 2007 ISUOG. Published by John Wiley & Sons, Ltd.

Methods for the Precise Locating and Forming of Arrays of Curved Features into a Workpiece

DOEpatents

Gill, David Dennis; Keeler, Gordon A.; Serkland, Darwin K.; Mukherjee, Sayan D.

2008-10-14

Methods for manufacturing high precision arrays of curved features (e.g. lenses) in the surface of a workpiece are described utilizing orthogonal sets of inter-fitting locating grooves to mate a workpiece to a workpiece holder mounted to the spindle face of a rotating machine tool. The matching inter-fitting groove sets in the workpiece and the chuck allow precisely and non-kinematically indexing the workpiece to locations defined in two orthogonal directions perpendicular to the turning axis of the machine tool. At each location on the workpiece a curved feature can then be on-center machined to create arrays of curved features on the workpiece. The averaging effect of the corresponding sets of inter-fitting grooves provide for precise repeatability in determining, the relative locations of the centers of each of the curved features in an array of curved features.

GFAAS determination of selenium in infant formulas using a microwave digestion method.

PubMed

Alegria, A; Barbera, R; Farré, R; Moreno, A

1994-01-01

A method for determining the selenium content of infant formulas is proposed. It includes wet digestion with nitric acid and hydrogen peroxide in medium pressure teflon bombs in a microwave oven and determination by graphite furnace atomic absorption spectrometry (GFAAS). The absence of interferences is checked. Values obtained for the limit of detection (19.4 ng/g), precision (RSD = 2.2%) and accuracy by analysis of a reference material show that the method is reliable.

Absolute Enumeration of Probiotic Strains Lactobacillus acidophilus NCFM® and Bifidobacterium animalis subsp. lactis Bl-04 ® via Chip-Based Digital PCR.

PubMed

Hansen, Sarah J Z; Morovic, Wesley; DeMeules, Martha; Stahl, Buffy; Sindelar, Connie W

2018-01-01

The current standard for enumeration of probiotics to obtain colony forming units by plate counts has several drawbacks: long time to results, high variability and the inability to discern between bacterial strains. Accurate probiotic cell counts are important to confirm the delivery of a clinically documented dose for its associated health benefits. A method is described using chip-based digital PCR (cdPCR) to enumerate Bifidobacterium animalis subsp. lactis Bl-04 and Lactobacillus acidophilus NCFM both as single strains and in combination. Primers and probes were designed to differentiate the target strains against other strains of the same species using known single copy, genetic differences. The assay was optimized to include propidium monoazide pre-treatment to prevent amplification of DNA associated with dead probiotic cells as well as liberation of DNA from cells with intact membranes using bead beating. The resulting assay was able to successfully enumerate each strain whether alone or in multiplex. The cdPCR method had a 4 and 5% relative standard deviation (RSD) for Bl-04 and NCFM, respectively, making it more precise than plate counts with an industry accepted RSD of 15%. cdPCR has the potential to replace traditional plate counts because of its precision, strain specificity and the ability to obtain results in a matter of hours.

A HPLC-DAD method for the simultaneous determination of five marker components in the traditional herbal medicine Bangpungtongsung-san

PubMed Central

Weon, Jin Bae; Yang, Hye Jin; Ma, Jin Yeul; Ma, Choong Je

2011-01-01

Background: Bangpungtongsung-san, one of the traditional herbal medicines, was known to be a prescription for obesity. Objective: For the simultaneous determination of five components (paeoniflorin, 6-gingerol, decursin, geniposide, and glycyrrhizin) in Bangpungtongsung-san, a high-performance liquid chromatography with diode-array detector method was established. Materials and Methods: To develop the method, a reverse phase column, DIONEX C 18 (5 μm, 120 µ, 4.6 mm × 150 mm) was used. The mobile phase consisted of methanol and water using a gradient elution. The UV wavelength was set at 230, 240, and 254 nm. Method validation was accomplished by linearity, precision test, and recovery test. Results: All calibration curves of components showed good linearity (R 2 > 0.9959). The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.01 to 0.17 μg/ml and 0.04 to 0.53 μg/ml, respectively. The relative standard deviations (RSD) value of precision test, intraday and interday tests were less than 0.43% and 1.26%. In the recovery test, results of accuracy ranged from 95.27% to 107.70% with RSD values less than 2.21%. Conclusion: This developed method was applied to the commercial Bangpungtongsung-san sample and the five marker components were separated effectively without interference of any peaks of components. PMID:21472081

Effect-directed fingerprints of 77 botanical extracts via a generic high-performance thin-layer chromatography method combined with assays and mass spectrometry.

PubMed

Krüger, S; Hüsken, L; Fornasari, R; Scainelli, I; Morlock, G E

2017-12-22

Quantitative effect-directed profiles of 77 industrially and freshly extracted botanicals like herbs, spices, vegetables and fruits, widely used as food ingredients, dietary supplements or traditional medicine, gave relevant information on their quality. It allows the assessment of food, dietary supplements and phytomedicines with regard to potential health-promoting activities. In contrary to sum parameter assays and targeted analysis, chromatography combined with effect-directed analysis allows fast assignment of single active compounds and evaluation of their contribution to the overall activity, originating from a food or botanical sample. High-performance thin-layer chromatography was hyphenated with UV/Vis/FLD detection and effect-directed analysis, using the 2,2-diphenyl-1-picrylhydrazyl radical, Gram-negative Aliivibrio fischeri, Gram-positive Bacillus subtilis, acetylcholinesterase and tyrosinase assays. Bioactive compounds of interest were eluted using an elution head-based interface and further characterized by electrospray ionization (high-resolution) mass spectrometry. This highly streamlined workflow resulted in a hyphenated HPTLC-UV/Vis/FLD-EDA-ESI + /ESI - -(HR)MS method. The excellent quantification power of the method was shown on three compounds. For rosmarinic acid, contents ranged from 4.5mg/g (rooibos) to 32.6mg/g (rosemary), for kaempferol-3-glucoside from 0.6mg/g (caraway) to 4.4mg/g (wine leaves), and for quercetin-3-glucoside from 1.1mg/g (hawthorn leaves) to 17.7mg/g (thyme). Three mean repeatabilities (%RSD) over 18 quantifications for the three compounds were ≤2.2% and the mean intermediate precision over three different days (%RSD, n=3) was 5.2%. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination of amphetamine-type stimulants and cannabinoids in fingernails by gas chromatography-mass spectrometry.

PubMed

Kim, Jin Young; Cheong, Jae Chul; Kim, Min Kyoung; Lee, Jae Il; In, Moon Kyo

2008-06-01

A gas chromatography-mass spectrometric (GC-MS) method was developed and validated for the simultaneous detection and quantification of four amphetamine-type stimulants (amphetamine (AP), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA)) and two cannabinoids (Delta9-tetrahydrocannabinol (Delta9-THC) and 11-nor-Delta9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH)) in fingernails. Fingernail clippings (30 mg) were washed with distilled water and methanol, and then incubated in 1.0 M sodium hydroxide at 95 degrees C for 30 min. The compounds of interest were isolated by liquid-liquid extraction followed by derivatization with N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA) at 70 degrees C for 15 min. The derivatized compounds were analyzed by GC-MS in the selective ion monitoring (SIM) mode. The linear ranges were 0.1-15.0 ng/mg for AP, 0.2-15.0 ng/mg for MDA, Delta9-THC and THCCOOH, and 0.2-30.0 ng/mg for MA and MDMA, with good correlation coefficients (r2 > 0.9991). The intra-day, inter-day, and inter-person precisions were within 10.6%, 6.3%, and 5.3%, respectively. The intra-day, inter-day and inter-person accuracies were between -6.1 and 5.0%, -6.2 and 5.7%, and -6.4 and 5.6%, respectively. The limits of detection (LODs) and quantification (LOQs) for each compound were lower than 0.056 and 0.2 ng/mg, respectively. The recoveries were in the range of 74.0-94.8%. Positive GC-MS results were obtained from specimens of nine suspected MA or cannabis abusers. The concentration ranges of MA, AP, and THCCOOH were 0.10-1.41, 0.12-2.64, and 0.20 ng/mg, respectively. Based on these results, the method proved to be effective for the simultaneous qualification and quantification of amphetamine-type stimulants and cannabinoids in fingernails.

Determination of element/Ca ratios in foraminifera and corals using cold- and hot-plasma techniques in inductively coupled plasma sector field mass spectrometry

NASA Astrophysics Data System (ADS)

Lo, Li; Shen, Chuan-Chou; Lu, Chia-Jung; Chen, Yi-Chi; Chang, Ching-Chih; Wei, Kuo-Yen; Qu, Dingchuang; Gagan, Michael K.

2014-02-01

We have developed a rapid and precise procedure for measuring multiple elements in foraminifera and corals by inductively coupled plasma sector field mass spectrometry (ICP-SF-MS) with both cold- [800 W radio frequency (RF) power] and hot- (1200 W RF power) plasma techniques. Our quality control program includes careful subsampling protocols, contamination-free workbench spaces, and refined plastic-ware cleaning process. Element/Ca ratios are calculated directly from ion beam intensities of 24Mg, 27Al, 43Ca, 55Mn, 57Fe, 86Sr, and 138Ba, using a standard bracketing method. A routine measurement time is 3-5 min per dissolved sample. The matrix effects of nitric acid, and Ca and Sr levels, are carefully quantified and overcome. There is no significant difference between data determined by cold- and hot-plasma methods, but the techniques have different advantages. The cold-plasma technique offers a more stable plasma condition and better reproducibility for ppm-level elements. Long-term 2-sigma relative standard deviations (2-RSD) for repeat measurements of an in-house coral standard are 0.32% for Mg/Ca and 0.43% for Sr/Ca by cold-plasma ICP-SF-MS, and 0.69% for Mg/Ca and 0.51% for Sr/Ca by hot-plasma ICP-SF-MS. The higher sensitivity and enhanced measurement precision of the hot-plasma procedure yields 2-RSD precision for μmol/mol trace elements of 0.60% (Mg/Ca), 9.9% (Al/Ca), 0.68% (Mn/Ca), 2.7% (Fe/Ca), 0.50% (Sr/Ca), and 0.84% (Ba/Ca) for an in-house foraminiferal standard. Our refined ICP-SF-MS technique, which has the advantages of small sample size (2-4 μg carbonate consumed) and fast sample throughput (5-8 samples/hour), should open the way to the production of high precision and high resolution geochemical records for natural carbonate materials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoegg, Edward D.; Barinaga, Charles J.; Hager, George J.

Abstract The continued development of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma as an ion source for diverse, elemental/isotopic analysis applications continues. To this end, characterization of the capabilities in performing precise and accurate isotope ratio (IR) determinations is essential. Based on past experience with the Thermo Exactive Orbitrap mass analyzer, the LS-APGD was interfaced with this instrument for these tests. While the Orbitrap platform has demonstrated excellent mass resolution and accuracy in “organic” mass spectrometry (MS) applications, work using an Orbitrap for IR analysis is very sparse. These efforts build off previous work in this coupling, where themore » importance of a few of the LS-APGD discharge parameters and Orbitrap data acquisition methods on IR precision and accuracy were probed. Presented here are the results of a study that evaluated the analytical precision for natural uranium sample (assumed 235U/238U = 0.0072) determinations. The instrumental parameters evaluated include the number of microscans and scans making up a data acquisition set, uranium concentration/signal level, sample make-up, and Fourier transform digitization window. Ultimately, a precision of 0.41% relative standard deviation (RSD) can be achieved for a single determination, with a reproducibility of 1.63 %RSD over 10 separate analytical measurements. A preliminary study of matrix effects on IR measurements of U is presented, highlighting the importance of pre-mass selection before injection into the Orbitrap. The analytical system sensitivity is suggested with the ability to produce a calibration function having an R2 value of >0.99 over a range of 4 orders of magnitude of concentration (~1 – 1000 ng mL-1). These efforts demonstrate the very promising pairing of the LS-APGD ionization source and the Orbitrap, pointing as well to definitive paths forward to better utilize both components in high quality isotope ratio mass spectrometry (IRMS).« less

Rapid method for the determination of 14 isoflavones in food using UHPLC coupled to photo diode array detection.

PubMed

Shim, You-Shin; Yoon, Won-Jin; Hwang, Jin-Bong; Park, Hyun-Jin; Seo, Dongwon; Ha, Jaeho

2015-11-15

A rapid method for the determination of 14 types of isoflavones in food using ultra-high performance liquid chromatography (UHPLC) was validated in terms of precision, accuracy, sensitivity and linearity. The UHPLC separation was performed on a reverse-phase C18 column (particle size 2 μm, i.d. 2 mm, length 100 mm) using a photo diode array detector that was fixed to 260 nm. The limits of detection and quantification of the UHPLC analyses ranged from 0.03 to 0.33 mg kg(-1). The intra-day and inter-day precision of the individual isoflavones were less than 11.77% and calibration curves exhibited good linearity (r(2) = 0.99) within the tested ranges. These results suggest that the rapid method used in this study could be available to determine of 14 types of isoflavones in a variety of food such as soy bean, black bean, red bean and soybean paste. Copyright © 2015 Elsevier Ltd. All rights reserved.

Validated method for the analysis of goji berry, a rich source of zeaxanthin dipalmitate.

PubMed

Karioti, Anastasia; Bergonzi, Maria Camilla; Vincieri, Franco F; Bilia, Anna Rita

2014-12-31

In the present study an HPLC-DAD method was developed for the determination of the main carotenoid, zeaxanthin dipalmitate, in the fruits of Lycium barbarum. The aim was to develop and optimize an extraction protocol to allow fast, exhaustive, and repeatable extraction, suitable for labile carotenoid content. Use of liquid N2 allowed the grinding of the fruit. A step of ultrasonication with water removed efficiently the polysaccharides and enabled the exhaustive extraction of carotenoids by hexane/acetone 50:50. The assay was fast and simple and permitted the quality control of a large number of commercial samples including fruits, juices, and a jam. The HPLC method was validated according to ICH guidelines and satisfied the requirements. Finally, the overall method was validated for precision (% RSD ranging between 3.81 and 4.13) and accuracy at three concentration levels. The recovery was between 94 and 107% with RSD values <2%, within the acceptable limits, especially if the difficulty of the matrix is taken into consideration.

Gravimetric method for the determination of diclofenac in pharmaceutical preparations.

PubMed

Tubino, Matthieu; De Souza, Rafael L

2005-01-01

A gravimetric method for the determination of diclofenac in pharmaceutical preparations was developed. Diclofenac is precipitated from aqueous solution with copper(II) acetate in pH 5.3 (acetic acid/acetate buffer). Sample aliquots had approximately the same quantity of the drug content in tablets (50 mg) or in ampules (75 mg). The observed standard deviation was about +/- 2 mg; therefore, the relative standard deviation (RSD) was approximately 4% for tablet and 3% for ampule preparations. The results were compared with those obtained with the liquid chromatography method recommended in the United States Pharmacopoeia using the statistical Student's t-test. Complete agreement was observed. It is possible to obtain more precise results using higher aliquots, for example 200 mg, in which case the RSD falls to 1%. This gravimetric method, contrary to what is expected for this kind of procedure, is relatively fast and simple to perform. The main advantage is the absolute character of the gravimetric analysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wahyuni, Wulan Tri, E-mail: wulantriws@gmail.com; Department of Chemistry, FMIPA, Universitas Indonesia, Kampus UI Depok; Ivandini, Tribidasari A.

Biomolecule modified magnetic beads has been widely used in separation and sensing process. This study used streptavidin modified magnetic beads to immobilize biotin modified zanamivir. Biotin-streptavidin affinity facilitates immobilization of zanamivir on magnetic beads. Then interaction of zanamivir and neuraminidase was adopted as basic for enzyme detection. Detection of neuraminidase was performed at gold modified BDD using cyclic voltammetry technique. The measurement was carried out based on alteration of electrochemical signals of working electrode as neuraminidase response. The result showed that zanamivir was successfully immobilized on magnetic beads. The optimum amount of magnetic beads for zanamivir immobilization was 120 ug.more » Linear responses of neuraminidase were detected in concentration range of 0-15 mU. Detection limit (LOD) of measurement was 2.32 mU (R2 = 0.959) with precision as % RSD of 1.41%. Measurement of neuraminidase on magnetic beads could be also performed in the presence of mucin matrix. The linearity range was 0-8 mU with LOD of 0.64 mU (R2 = 0.950) and % RSD of 7.25%.« less

Determination of acrylamide and methacrylamide by normal phase high performance liquid chromatography and UV detection.

PubMed

Paleologos, E K; Kontominas, M G

2005-06-10

A method using normal phase high performance liquid chromatography (NP-HPLC) with UV detection was developed for the analysis of acrylamide and methacrylamide. The method relies on the chromatographic separation of these analytes on a polar HPLC column designed for the separation of organic acids. Identification of acrylamide and methacrylamide is approached dually, that is directly in their protonated forms and as their hydrolysis products acrylic and methacrylic acid respectively, for confirmation. Detection and quantification is performed at 200 nm. The method is simple allowing for clear resolution of the target peaks from any interfering substances. Detection limits of 10 microg L(-1) were obtained for both analytes with the inter- and intra-day RSD for standard analysis lying below 1.0%. Use of acetonitrile in the elution solvent lowers detection limits and retention times, without impairing resolution of peaks. The method was applied for the determination of acrylamide and methacrylamide in spiked food samples without native acrylamide yielding recoveries between 95 and 103%. Finally, commercial samples of french and roasted fries, cookies, cocoa and coffee were analyzed to assess applicability of the method towards acrylamide, giving results similar with those reported in the literature.

Simple equation for calculation of plasma clearance for evaluation of renal function without urine collection in rats.

PubMed

Liu, Xiang; Peng, Dejun; Tian, Hao; Lu, Chengyu

2017-01-01

To develop an equation for the evaluation of renal function in rats using three dilutions of plasma samples and to validate this method by comparison with a reference method. The investigation was conducted in Sprague-Dawley (SD) rats after delivery of three doses of iohexol, with blood samples collected before and after dosage using a quantitative blood collection method. Plasma iohexol concentrations were detected by high performance liquid chromatography (HPLC). The extraction recovery of iohexol from plasma was >97.30% and the calibration curve was linear (r 2  = 0.9997) over iohexol concentrations ranging from 10 to 1000 µg/mL. The method had an RE of <9.310 and intra- and inter-day RSD of <5.137% and <3.693%, respectively. The plasma clearance values obtained from the equation correlated closely (r = 0.763) with those obtained using the reference method. The relatively correlation in the results obtained using the method under investigation and the reference method indicate that this new equation can be used for preliminary assessment of renal function in rats. © 2016 Asian Pacific Society of Nephrology.

An ultraviolet-spectrophotometric method for the determination of glimepiride in solid dosage forms.

PubMed

Afieroho, Ozadheoghene E; Okorie, Ogbonna; Okonkwo, Tochukwu J N

2011-06-01

Considering the cost of acquiring a liquid chromatographic instrument in underdeveloped economies, the rising incidence of diabetes mellitus, the need to evaluate the quality performance of glimepiride generics, and the need for less toxic processes, this research is an imperative. The method was validated for linearity, recovery accuracy, intra- and inter-day precision, specificity in the presence of excipients, and inter-day stability under laboratory conditions. Student's t test at the 95% confidence limit was used for statistics. Using 96% ethanol as solvent, a less toxic and cost-effective spectrophotometric method for the determination of glimepiride in solid dosage forms was developed and validated. The results of the validated parameters showed a λ(max) of 231 nm, linearity range of 0.5-22 μg/mL, precision with relative SD of <1.0%, recovery accuracy of 100.8%, regression equation of y = 45.741x + 0.0202, R(2) = 0.999, limit of detection of 0.35 μg/mL, and negligible interference from common excipients and colorants. The method was found to be accurate at the 95% confidence limit compared with the standard liquid chromatographic method with comparable reproducibility when used to assay the formulated products Amaryl(®) (sanofi-aventis, Paris, France) and Mepyril(®) (May & Baker Nigeria PLC, Ikeja, Nigeria). The results obtained for the validated parameters were within allowable limits. This method is recommended for routine quality control analysis.

Development and validation of a rapid reverse-phase HPLC method for the determination of methotrexate from nanostructured liquid crystalline systems.

PubMed

Zuben, E S Von; Oliveira, A G; Chorilli, M; Scarpa, M V

2018-03-05

A reversed-phase liquid chromatography (RP-LC) method was successfully developed and validated for the determination of methotrexate in nanostructured liquid crystalline systems composed by polyether functional siloxane and silicone polyether copolymer. The LC method was performed on RP C18-ODS column, Agilent Zorbax® (4.6 x 250 mm, 5 μm), maintained at room temperature, with a mobile phase constituted by a mixture of 50 mM ammonium acetate buffer (pH 6.0) and methanol (77:23,v/v) with a flow rate of 1.0 mL/min, using ultraviolet detection at 313 nm. The parameters used in the validation process were linearity, specificity, intra and inter-day precision, accuracy, robustness. The quantitation and detection limits yielded good results. The calibration plot assumed linear behavior from 5.0-150.0 μg. mL-1 (r2 = 0.9999). The methotrexate was subjected to oxidation, acid, base and neutral degradation, photolysis and heat as stress conditions. There were no interfering peaks at or near the retention time of methotrexate. The nanostructured liquid crystalline systems did not interfere with the analysis and the recovery was quantitative. The intra and inter-day assay relative standard deviation were less than 0.20 %. The method developed proved to be simple, sensitive, accurate, precise, reproducible and therefore adequate for routine analysis of methotrexate in nanostructured liquid crystalline systems.

A validated solid-phase extraction HPLC method for the simultaneous determination of the citrus flavanone aglycones hesperetin and naringenin in urine.

PubMed

Kanaze, Feras Imad; Kokkalou, Eugene; Georgarakis, Manolis; Niopas, Ioannis

2004-09-21

A simple, specific, precise, accurate, and robust HPLC assay for the simultaneous analysis of hesperetin and naringenin in human urine was developed and validated. Urine samples were incubated with beta-glucuronidase/sulphatase and the analytes were isolated by solid-phase extraction using C18 cartridges and separated on a C8 reversed phase column using a mixture of methanol/water/acetic acid (40:58:2, v/v/v) at 45 degrees C. The method was found to be linear in the 50-1200 ng/ml concentration range for both hesperetin and naringenin (r > 0.999). The accuracy of the method was greater than 94.8%, while the intra- and inter-day precision for hesperetin was better than 4.9 and 8.2%, respectively and for naringenin was better than 5.3 and 7.8%, respectively. Recovery for hesperetin, naringenin and internal standard 7-ethoxycoumarin was greater than 70.9%. The method has been applied for the determination of hesperetin and naringenin in urine samples obtained from a male volunteer following a single 300 mg oral dose of each of the corresponding flavanone glycosides hesperidin and naringin. The intra- and inter-day reproducibility through enzyme hydrolysis was less than 3.9% for both total (free + conjugated) hesperetin and naringenin. Stability studies showed urine quality control samples to be stable for both hesperetin and naringenin through three freeze-thaw cycles and at room temperature for 24 h (error < or = 3.6%).

Comparative permeability studies with radioactive and nonradioactive risedronate sodium from self-microemulsifying drug delivery system and solution.

PubMed

Ilem-Ozdemir, Derya; Gundogdu, Evren; Ekinci, Meliha; Ozgenc, Emre; Asikoglu, Makbule

2015-01-01

The purpose of this work is to prepare a self-microemulsifying drug delivery system (SMEDDS) for risedronate sodium (RSD) and to compare the permeability with RSD solution. The solubility of RSD was determined in different vehicles. Phase diagrams were constructed to determine the optimum concentration of oil, surfactant, and cosurfactant. RSD SMEDDS was prepared by using a mixture of soybean oil, cremophor EL, span 80, and transcutol (2.02:7.72:23.27:61.74, w/w, respectively). The prepared RSD SMEDDS was characterized by droplet size value. In vitro Caco-2 cell permeability studies were performed for SMEDDS and solution of radioactive ((99 m)Tc-labeled RSD) and nonradioactive RSD. The experimental results indicated that RSD SMEDDS has good stability and its droplet size is between 216.68 ± 3.79 and 225.26 ± 7.65 during stability time. In addition, RSD SMEDDS has higher permeability value than the RSD solution for both radioactive and nonradioactive experiments. The results illustrated the potential use of SMEDDS for delivery of poorly absorbed RSD.

The 25th anniversary of the retrograde suction decompression technique (Dallas technique) for the surgical management of paraclinoid aneurysms: historical background, systematic review, and pooled analysis of the literature.

PubMed

Flores, Bruno C; White, Jonathan A; Batjer, H Hunt; Samson, Duke S

2018-05-04

OBJECTIVE Paraclinoid internal carotid artery (ICA) aneurysms frequently require temporary occlusion to facilitate safe clipping. Brisk retrograde flow through the ophthalmic artery and cavernous ICA branches make simple trapping inadequate to soften the aneurysm. The retrograde suction decompression (RSD), or Dallas RSD, technique was described in 1990 in an attempt to overcome some of those treatment limitations. A frequent criticism of the RSD technique is an allegedly high risk of cervical ICA dissection. An endovascular modification was introduced in 1991 (endovascular RSD) but no studies have compared the 2 RSD variations. METHODS The authors performed a systematic review of MEDLINE/PubMed and Web of Science and identified all studies from 1990-2016 in which either Dallas RSD or endovascular RSD was used for treatment of paraclinoid aneurysms. A pooled analysis of the data was completed to identify important demographic and treatment-specific variables. The primary outcome measure was defined as successful aneurysm obliteration. Secondary outcome variables were divided into overall and RSD-specific morbidity and mortality rates. RESULTS Twenty-six RSD studies met the inclusion criteria (525 patients, 78.9% female). The mean patient age was 53.5 years. Most aneurysms were unruptured (56.6%) and giant (49%). The most common presentations were subarachnoid hemorrhage (43.6%) and vision changes (25.3%). The aneurysm obliteration rate was 95%. The mean temporary occlusion time was 12.7 minutes. Transient or permanent morbidity was seen in 19.9% of the patients. The RSD-specific complication rate was low (1.3%). The overall mortality rate was 4.2%, with 2 deaths (0.4%) attributable to the RSD technique itself. Good or fair outcome were reported in 90.7% of the patients. Aneurysm obliteration rates were similar in the 2 subgroups (Dallas RSD 94.3%, endovascular RSD 96.3%, p = 0.33). Despite a higher frequency of complex (giant or ruptured) aneurysms, Dallas RSD was associated with lower RSD-related morbidity (0.6% vs 2.9%, p = 0.03), compared with the endovascular RSD subgroup. There was a trend toward higher mortality in the endovascular RSD subgroup (6.4% vs 3.1%, p = 0.08). The proportion of patients with poor neurological outcome at last follow-up was significantly higher in the endovascular RSD group (15.4% vs 7.2%, p < 0.01). CONCLUSIONS The treatment of paraclinoid ICA aneurysms using the RSD technique is associated with high aneurysm obliteration rates, good long-term neurological outcome, and low RSD-related morbidity and mortality. Review of the RSD literature showed no evidence of a higher complication rate associated with the Dallas technique compared with similar endovascular methods. On a subgroup analysis of Dallas RSD and endovascular RSD, both groups achieved similar obliteration rates, but a lower RSD-related morbidity was seen in the Dallas technique subgroup. Twenty-five years after its initial publication, RSD remains a useful neurosurgical technique for the management of large and giant paraclinoid aneurysms.

Intra-/inter-laboratory validation study on reactive oxygen species assay for chemical photosafety evaluation using two different solar simulators.

PubMed

Onoue, Satomi; Hosoi, Kazuhiro; Toda, Tsuguto; Takagi, Hironori; Osaki, Naoto; Matsumoto, Yasuhiro; Kawakami, Satoru; Wakuri, Shinobu; Iwase, Yumiko; Yamamoto, Toshinobu; Nakamura, Kazuichi; Ohno, Yasuo; Kojima, Hajime

2014-06-01

A previous multi-center validation study demonstrated high transferability and reliability of reactive oxygen species (ROS) assay for photosafety evaluation. The present validation study was undertaken to verify further the applicability of different solar simulators and assay performance. In 7 participating laboratories, 2 standards and 42 coded chemicals, including 23 phototoxins and 19 non-phototoxic drugs/chemicals, were assessed by the ROS assay using two different solar simulators (Atlas Suntest CPS series, 3 labs; and Seric SXL-2500V2, 4 labs). Irradiation conditions could be optimized using quinine and sulisobenzone as positive and negative standards to offer consistent assay outcomes. In both solar simulators, the intra- and inter-day precisions (coefficient of variation; CV) for quinine were found to be below 10%. The inter-laboratory CV for quinine averaged 15.4% (Atlas Suntest CPS) and 13.2% (Seric SXL-2500V2) for singlet oxygen and 17.0% (Atlas Suntest CPS) and 7.1% (Seric SXL-2500V2) for superoxide, suggesting high inter-laboratory reproducibility even though different solar simulators were employed for the ROS assay. In the ROS assay on 42 coded chemicals, some chemicals (ca. 19-29%) were unevaluable because of limited solubility and spectral interference. Although several false positives appeared with positive predictivity of ca. 76-92% (Atlas Suntest CPS) and ca. 75-84% (Seric SXL-2500V2), there were no false negative predictions in both solar simulators. A multi-center validation study on the ROS assay demonstrated satisfactory transferability, accuracy, precision, and predictivity, as well as the availability of other solar simulators. Copyright © 2013 Elsevier Ltd. All rights reserved.

Method development for the determination of fluorine in toothpaste via molecular absorption of aluminum mono fluoride using a high-resolution continuum source nitrous oxide/acetylene flame atomic absorption spectrophotometer.

PubMed

Ozbek, Nil; Akman, Suleyman

2012-05-30

Fluorine was determined via the rotational molecular absorption line of aluminum mono fluoride (AlF) generated in C(2)H(2)/N(2)O flame at 227.4613 nm using a high-resolution continuum source flame atomic absorption spectrophotometer (HR-CS-FAAS). The effects of AlF wavelength, burner height, fuel rate (C(2)H(2)/N(2)O) and amount of Al on the accuracy, precision and sensitivity were investigated and optimized. The Al-F absorption band at 227.4613 nm was found to be the most suitable analytical line with respect to sensitivity and spectral interferences. Maximum sensitivity and a good linearity were obtained in acetylene-nitrous oxide flame at a flow rate of 210 L h(-1) and a burner height of 8mm using 3000 mg L(-1) of Al for 10-1000 mg L(-1)of F. The accuracy and precision of the method were tested by analyzing spiked samples and waste water certified reference material. The results were in good agreement with the certified and spiked amounts as well as the precision of several days during this study was satisfactory (RSD<10%). The limit of detection and characteristic concentration of the method were 5.5 mg L(-1) and 72.8 mg L(-1), respectively. Finally, the fluorine concentrations in several toothpaste samples were determined. The results found and given by the producers were not significantly different. The method was simple, fast, accurate and sensitive. Copyright © 2012 Elsevier B.V. All rights reserved.

Endovascular ultrasound for renal sympathetic denervation in patients with therapy-resistant hypertension not responding to radiofrequency renal sympathetic denervation.

PubMed

Stiermaier, Thomas; Okon, Thomas; Fengler, Karl; Mueller, Ulrike; Hoellriegel, Robert; Schuler, Gerhard; Desch, Steffen; Lurz, Philipp

2016-06-12

Recent studies have reported a considerable number of non-responders after renal sympathetic de-nervation (RSD) with radiofrequency technology. Here we report our results of repeat RSD using ultrasound in these patients. A cohort study was performed in patients who underwent ultrasound RSD after non-response to RSD with radiofrequency. Non-response was defined as mean daytime systolic blood pressure ≥140 mmHg and/or a reduction of ≤10 mmHg in ambulatory blood pressure measurement (ABPM) ≥6 months after radiofrequency denervation. ABPM was recorded at baseline, post radiofrequency RSD as well as at three and six months post ultrasound RSD. A total of 24 non-responders underwent retreatment with the ultrasound device at a mean 15.3±8.2 months after radiofrequency RSD. Ultrasound RSD was performed successfully in all patients without severe adverse events. Mean daytime systolic blood pressure changed from 161.7±14.6 mmHg at baseline to 158.5±9.5 mmHg post radiofrequency RSD and to 150.5±10.4 mmHg and 151.6±11.0 mmHg at three and six months, respectively, post ultrasound RSD (p<0.01 with repeated measures analysis of variance). The main results of post hoc testing were as follows: baseline versus post radiofrequency RSD, p=0.83; baseline versus three months post ultrasound RSD, p=0.01; and baseline versus six months post ultrasound RSD, p=0.04. Ultrasound RSD appears to be safe and an effective therapeutic approach in patients not responding to previous RSD with radiofrequency technology.

Testing of nylon 6 nanofibers with different surface densities as sorbents for solid phase extraction and their selectivity comparison with commercial sorbent.

PubMed

Háková, Martina; Raabová, Hedvika; Havlíková, Lucie Chocholoušová; Chocholouš, Petr; Chvojka, Jiří; Šatínský, Dalibor

2018-05-01

Nylon 6 nanofibers were tested for their ability to serve as a sorbent for solid phase extraction (SPE). The regular nanostructure providing a great sorption area and amidic functionality should lead to the assumption that nylon 6 nanofibers could be used as a novel sorbent with great potential for sample pre-treatment. However, due to the substantial differences between classical particle sorbents used for solid phase extraction and nanofibers, it is necessary to evaluate this novel approach. This article describes three types of laboratory fabricated nylon 6 nanofibers with different surface density (5.04gm -2 , 3.90gm -2 and 0.75gm -2 ) and corresponding surface areas for solid phase extraction of several groups of compounds with different structural and physicochemical properties (parabens, steroids, flavonoids and pesticides). The nanofibers were created by needleless electrospinning. Extraction columns were manually packed in classic 1- or 3-mL plastic syringe cartridges with 26-30mg of nanofibers and the column bed was sealed with polypropylene frits. The SPE procedure followed a typical five-step protocol and the collected eluates were analyzed by HPLC with UV detection. Extraction recovery was used as a parameter to evaluate the behavior of the analytes within the SPE process. Under this set condition, the recovery of the SPE process ranged from 23.1% to 125.8%. SPE showed good repeatability (0.58-11.87% RSD) and inter-day reproducibility (3.86-9.79% RSD). The achieved results were compared with SPE using a classic particle sorbent column. Good mechanical and chemical stability of nanofibers was proved. Scanning electron microscope was used for the evaluation of morphological changes in nanostructure. Nylon 6 nanofibers proved being a cost-effective sorbent for repeated use in SPE. Nylon 6 nanofibers have great potential in miniaturized SPE enabling users to overcome troubles with high back-pressure. Copyright © 2018 Elsevier B.V. All rights reserved.

Fabrication of ciprofloxacin molecular imprinted polymer coating on a stainless steel wire as a selective solid-phase microextraction fiber for sensitive determination of fluoroquinolones in biological fluids and tablet formulation using HPLC-UV detection.

PubMed

Mirzajani, Roya; Kardani, Fatemeh

2016-04-15

A molecularly imprinted polymer (MIP) fiber on stainless steel wire using ciprofloxacin template with a mild template removal condition was synthetized and evaluated for fiber solid phase microextraction (SPME) of fluoroquinolones (FQs) from biological fluids and pharmaceutical samples, followed by high performance liquid chromatography analysis with UV detection (HPLC-UV). The developed MIP fiber exhibited high selectivity for the analytes in complex matrices. The coating of the fibers were inspected using fourier transform infrared spectrophotometry, thermogaravimetric analysis, energy dispersive X-ray (EDX) spectroscopy as well as by scanning electron microscopy (SEM). The fiber shows high thermal stability (up to 300°C), good reproducibility and long lifetime. The composite coating did not swell in organic solvents nor did it strip off from the substrate. It was also highly stable and extremely adherent to the surface of the stainless steel fiber. The fabricated fiber exclusively exhibited excellent extraction efficiency and selectivity for some FQs. The effective parameters influencing the microextraction efficiency such as pH, extraction time, desorption condition, and stirring rate were investigated. Under optimized conditions, the limits of detection of the four FQs ranged from 0.023-0.033 μg L(-1) (S/N=5) and the calibration graphs were linear in the concentration range from 0.1-40 μg L(-1), the inter-day and intraday relative standard deviations (RSD) for various FQs at three different concentration level (n=5) using a single fiber were 1.1-4.4% and the fiber to fiber RSD% (n=5) was 4.3-6.7% at 5 μg L(-1) of each anlyetes. The method was successfully applied for quantification of FQs in real samples including serum, plasma and tablet formulation with the recoveries between 97 to 102%. Copyright © 2016 Elsevier B.V. All rights reserved.

The Caenorhabditis elegans rsd-2 and rsd-6 genes are required for chromosome functions during exposure to unfavorable environments.

PubMed

Han, Wang; Sundaram, Prema; Kenjale, Himanshu; Grantham, James; Timmons, Lisa

2008-04-01

In Caenorhabditis elegans, exogenous dsRNA can elicit systemic RNAi, a process that requires the function of many genes. Considering that the activities of many of these genes are also required for normal development, it is surprising that exposure to high concentrations of dsRNA does not elicit adverse consequences to animals. Here, we report inducible phenotypes in attenuated C. elegans strains reared in environments that include nonspecific dsRNA and elevated temperature. Under these conditions, chromosome integrity is compromised in RNAi-defective strains harboring mutations in rsd-2 or rsd-6. Specifically, rsd-2 mutants display defects in transposon silencing, while meiotic chromosome disjunction is affected in rsd-6 mutants. RSD-2 proteins localize to multiple cellular compartments, including the nucleolus and cytoplasmic compartments that, in part, are congruent with calreticulin and HAF-6. We considered that the RNAi defects in rsd-2 mutants might have relevance to membrane-associated functions; however, endomembrane compartmentalization and endocytosis/exocytosis markers in rsd-2 and rsd-6 mutants appear normal. The mutants also possess environmentally sensitive defects in cell-autonomous RNAi elicited from transgene-delivered dsRNAs. Thus, the ultimate functions of rsd-2 and rsd-6 in systemic RNAi are remarkably complex and environmentally responsive.

Determination of geniposide in adjuvant arthritis rat plasma by ultra-high performance liquid chromatography tandem mass spectrometry method and its application to oral bioavailability and plasma protein binding ability studies.

PubMed

Chen, Jian; Wu, Hong; Xu, Guo-Bing; Dai, Miao-Miao; Hu, Shun-Li; Sun, Liang-Liang; Wang, Wei; Wang, Rong; Li, Shu-Pin; Li, Guo-Qiang

2015-04-10

A specific, sensitive and high throughput ultra-high performance liquid chromatography-electrospray ionization tandem mass spectrometric method (UHPLC-ESI-MS/MS) was established and validated to assay geniposide (GE), a promising anti-inflammatory drug, in adjuvant arthritis rat plasma: application to pharmacokinetic and oral bioavailability studies and plasma protein binding ability. Plasma samples were processed by de-proteinised with ice-cold methanol and separated on an ACQUITY UPLC™ HSS C18 column (100 mm × 2.1mm i.d., 1.8 μm particle size) at a gradient flow rate of 0.2 mL/min using acetonitrile-0.1% formic acid in water as mobile phase, and the total run time was 9 min. Mass detection was performed in selected reaction monitoring (SRM) mode with negative electro-spray ionization includes the addition of paeoniflorin (Pae) as an internal standard (IS). The mass transition ion-pair was followed as m/z 387.4 → 122.4 for GE and m/z 479.4 → 449.0 for IS. The calibration curves were linear over the concentration range of 2-50,000 ng/mL with lower limit of quantification of 2 ng/mL. The intra-day and inter-day precisions (RSD, %) of the assay were less than 8.4%, and the accuracy was within ± 6.4% in terms of relative error (RE). Extraction recovery, matrix effect and stability were satisfactory in adjuvant arthritis rat plasma. The UHPLC-ESI-MS/MS method was successfully applied to a pharmacokinetic study of GE after oral administration of depurated GE at 33, 66, 132 mg/kg and intravenous injection at 33, 66, 132 mg/kg in adjuvant arthritis (AA) rats. In addition, it was found that GE has rapid absorption and elimination, low absolute bioavailability, high plasma protein binding ability in AA rats after oral administration within the tested dosage range. It suggested that GE showed slow distribution into the intra- and extracellular space, and the binding rate was not proportionally dependent on plasma concentration of GE when the concentration of GE was below 5.0 μg/mL. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous Determination of Vinpocetine and its Major Active Metabolite Apovincaminic Acid in Rats by UPLC-MS/MS and its Application to the Brain Tissue Distribution Study.

PubMed

Wang, Manman; Wang, Lijuan; Sun, Jinghan; Zhang, Lili; Zhao, Longshan; Xiong, Zhili

2018-03-01

A specific, rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method was developed for simultaneous determination of vinpocetine (VP) and its active metabolite, apovincaminic acid (AVA) in rat brain regions, such as hypothalamus, striatum, cortex, cerebellum and hippocampus. Phenacetin was used as internal standard (IS). Brain tissue samples were precipitated protein by using 500 μL methanol. The separation was achieved on a Waters ACQUITY UPLC BEH C18 column (100 mm × 2.1 mm, 1.7 μm), using a methanol-water gradient elution at the flow rate of 0.20 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer in multiple reaction monitoring (MRM) mode via positive electrospray ionization source (ESI). The quantification was operated using the transitions of m/z 351 → m/z 280 for VP, m/z 323 → m/z 280 for AVA and m/z 180 → m/z 110 for IS, respectively. The calibration curve was linear in concentration range from 0.100 to 60.0 ng/mL for VP and 0.103 to 6.18 ng/mL for AVA. The intra-day and inter-day precision (relative standard deviation, RSD) values were within 11.8%, the accuracy (relative error, RE) was from -1.7% to 3.0% for VP and 2.7% to 9.5% for AVA at all the three concentration levels of quality-control (QC) samples. The improved UPLC-MS/MS method was specific, rapid and sensitive, which was further successfully applied to simultaneous determination of VP and AVA in different rat brain regions after intragastric administration of 4 mg/kg VP. It was indicated that VP could be eliminated quickly in brain, while the elimination of AVA was slow and it could be maintained for more than 12 h in brain. Moreover, it was found that the contents of VP and AVA were much higher in the hypothalamus, striatum and cortex than those in the cerebellum and hippocampus, which verified the distribution characteristics of VP and AVA in different brain regions from the point of quantitation in rats.

A method for fast determination of psoralens in oral solutions of phytomedicines using liquid chromatography.

PubMed

Pires, Adriana Elias; Honda, Neli Kiko; Cardoso, Cláudia Andréa Lima

2004-10-29

A method for sample preparation and analysis by high performance liquid chromatography with UV detection (HPLC-UV) has been developed for routine analysis of psoralen and bergapten, photosensitizing compounds, in oral solutions of phytomedicines employed in Brazil for some illnesses. The linearity, accuracy, the inter- and intra-day precision of the procedure were evaluated. Calibration curves for psoralen and bergapten were linear in the range of 1.0-600.0 microg ml(-1) and 1.0-400.0 microg ml(-1) respectively. The recoveries of the psoralens in the oral solutions analysed were 94.43-99.97%. The percentage coefficient of variation (CV) of the quantitative analysis of the psoralens in the products analysis was within 5%. In inter-equipment study was employed gas chromatography-flame ionization (CG-FID) detection.

Crystal structure of the Escherichia coli regulator of sigma70, Rsd, in complex with sigma70 domain 4.

PubMed

Patikoglou, Georgia A; Westblade, Lars F; Campbell, Elizabeth A; Lamour, Valérie; Lane, William J; Darst, Seth A

2007-09-21

The Escherichia coli Rsd protein binds tightly and specifically to the RNA polymerase (RNAP) sigma(70) factor. Rsd plays a role in alternative sigma factor-dependent transcription by biasing the competition between sigma(70) and alternative sigma factors for the available core RNAP. Here, we determined the 2.6 A-resolution X-ray crystal structure of Rsd bound to sigma(70) domain 4 (sigma(70)(4)), the primary determinant for Rsd binding within sigma(70). The structure reveals that Rsd binding interferes with the two primary functions of sigma(70)(4), core RNAP binding and promoter -35 element binding. Interestingly, the most highly conserved Rsd residues form a network of interactions through the middle of the Rsd structure that connect the sigma(70)(4)-binding surface with three cavities exposed on distant surfaces of Rsd, suggesting functional coupling between sigma(70)(4) binding and other binding surfaces of Rsd, either for other proteins or for as yet unknown small molecule effectors. These results provide a structural basis for understanding the role of Rsd, as well as its ortholog, AlgQ, a positive regulator of Pseudomonas aeruginosa virulence, in transcription regulation.

Crystal structure of the Escherichia coli regulator of σ70, Rsd, in complex with σ70 domain 4

PubMed Central

Patikoglou, Georgia A.; Westblade, Lars F.; Campbell, Elizabeth A.; Lamour, Valérie; Lane, William J.; Darst, Seth A.

2007-01-01

Summary The Escherichia coli Rsd protein binds tightly and specifically to the RNA polymerase (RNAP) σ70 factor. Rsd plays a role in alternative σ factor-dependent transcription by biasing the competition between σ70 and alternative σ factors for the available core RNAP. Here, we determined the 2.6 Å-resolution X-ray crystal structure of Rsd bound to σ70 domain 4 (σ704), the primary determinant for Rsd binding within σ70. The structure reveals that Rsd binding interferes with the two primary functions of σ704, core RNAP binding and promoter –35 element binding. Interestingly, the most highly conserved Rsd residues form a network of interactions through the middle of the Rsd structure that connect the σ704-binding surface with three cavities exposed on distant surfaces of Rsd, suggesting functional coupling between σ704 binding and other binding surfaces of Rsd, either for other proteins or for as yet unknown small molecule effectors. These results provide a structural basis for understanding the role of Rsd, as well as its ortholog, AlgQ, a positive regulator of Pseudomonas aeruginosa virulence, in transcription regulation. PMID:17681541

Caenorhabditis elegans RSD-2 and RSD-6 promote germ cell immortality by maintaining small interfering RNA populations.

PubMed

Sakaguchi, Aisa; Sarkies, Peter; Simon, Matt; Doebley, Anna-Lisa; Goldstein, Leonard D; Hedges, Ashley; Ikegami, Kohta; Alvares, Stacy M; Yang, Liwei; LaRocque, Jeannine R; Hall, Julie; Miska, Eric A; Ahmed, Shawn

2014-10-14

Germ cells are maintained in a pristine non-aging state as they proliferate over generations. Here, we show that a novel function of the Caenorhabditis elegans RNA interference proteins RNAi spreading defective (RSD)-2 and RSD-6 is to promote germ cell immortality at high temperature. rsd mutants cultured at high temperatures became progressively sterile and displayed loss of small interfering RNAs (siRNAs) that target spermatogenesis genes, simple repeats, and transposons. Desilencing of spermatogenesis genes occurred in late-generation rsd mutants, although defective spermatogenesis was insufficient to explain the majority of sterility. Increased expression of repetitive loci occurred in both germ and somatic cells of late-generation rsd mutant adults, suggesting that desilencing of many heterochromatic segments of the genome contributes to sterility. Nuclear RNAi defective (NRDE)-2 promotes nuclear silencing in response to exogenous double-stranded RNA, and our data imply that RSD-2, RSD-6, and NRDE-2 function in a common transgenerational nuclear silencing pathway that responds to endogenous siRNAs. We propose that RSD-2 and RSD-6 promote germ cell immortality at stressful temperatures by maintaining transgenerational epigenetic inheritance of endogenous siRNA populations that promote genome silencing.

Caenorhabditis elegans RSD-2 and RSD-6 promote germ cell immortality by maintaining small interfering RNA populations

PubMed Central

Sakaguchi, Aisa; Sarkies, Peter; Simon, Matt; Doebley, Anna-Lisa; Goldstein, Leonard D.; Hedges, Ashley; Ikegami, Kohta; Alvares, Stacy M.; Yang, Liwei; LaRocque, Jeannine R.; Hall, Julie; Miska, Eric A.; Ahmed, Shawn

2014-01-01

Germ cells are maintained in a pristine non-aging state as they proliferate over generations. Here, we show that a novel function of the Caenorhabditis elegans RNA interference proteins RNAi spreading defective (RSD)-2 and RSD-6 is to promote germ cell immortality at high temperature. rsd mutants cultured at high temperatures became progressively sterile and displayed loss of small interfering RNAs (siRNAs) that target spermatogenesis genes, simple repeats, and transposons. Desilencing of spermatogenesis genes occurred in late-generation rsd mutants, although defective spermatogenesis was insufficient to explain the majority of sterility. Increased expression of repetitive loci occurred in both germ and somatic cells of late-generation rsd mutant adults, suggesting that desilencing of many heterochromatic segments of the genome contributes to sterility. Nuclear RNAi defective (NRDE)-2 promotes nuclear silencing in response to exogenous double-stranded RNA, and our data imply that RSD-2, RSD-6, and NRDE-2 function in a common transgenerational nuclear silencing pathway that responds to endogenous siRNAs. We propose that RSD-2 and RSD-6 promote germ cell immortality at stressful temperatures by maintaining transgenerational epigenetic inheritance of endogenous siRNA populations that promote genome silencing. PMID:25258416

Development and validation of an LC-MS method for determination of Karanjin in rat plasma: application to preclinical pharmacokinetics.

PubMed

Yi, Deliang; Wang, Zhihua; Yi, Longzhi

2015-04-01

A selective and sensitive liquid chromatography-mass spectrometry (MS) method was developed and validated for the determination of karanjin in rat plasma. The target analyte, together with the internal standard (warfarin), was extracted from rat plasma by liquid-liquid extraction with ethyl acetate. Chromatographic separation was performed on a ZORBAX SB-C18 column using a mixture of acetonitrile and 0.1% aqueous formic acid as the mobile phase with linear gradient elution. MS detection was performed on a single quadrupole MS by selected ion monitoring mode via a positive electrospray ionization source. The assay exhibited a linear dynamic range of 2.50-3,000 ng/mL for karanjin. The intra- and inter-day precision was <10.8%, and the intra- and inter-day accuracy was <9.2%. The validated method has been applied to the preclinical pharmacokinetic studies of karanjin following oral administration of 5, 10 and 20 mg/kg karanjin to rats. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Direct and simultaneous determination of representative byproducts in a lignocellulosic hydrolysate of corn stover via gas chromatography-mass spectrometry with a Deans switch.

PubMed

Zheng, Rongping; Zhang, Hongman; Zhao, Jing; Lei, Mingliu; Huang, He

2011-08-05

Pretreatment is one of the most important steps in producing fuel ethanol from lignocellulosic biomass. Simple, fast and accurate quantification of byproducts in lignocellulosic hydrolysates is critical to optimize the pretreatment procedures, but still a challenge. In this paper, a new GC-MS (SIM) method based on a Deans switch has been developed for the determination of byproducts in a corn stover hydrolysate. The Deans switch was incorporated into a hardware system that facilitated the direct aqueous injection (DAI) on GC-MS system. Simultaneous chromatographic separation and quantification of 18 byproducts including four aliphatic acids, five furan derivatives, four phenolic compounds and five others were achieved within 45 min. The detection limits of the presented method for various byproducts were in the range of 0.007-0.832 mg/L. The within-day and between-day precisions of the method were less than 6.0% (RSD, n=6). The accuracy of the method was confirmed with recoveries of 86-128%. A lignocellulosic hydrolysate sample of corn stover was successfully analyzed using this method, with aliphatic acids and furan derivatives accounting for 89.15% of the selected total byproducts. Copyright © 2011 Elsevier B.V. All rights reserved.

The histidine phosphocarrier protein, HPr, binds to the highly thermostable regulator of sigma D protein, Rsd, and its isolated helical fragments.

PubMed

Neira, José L; Hornos, Felipe; Cozza, Concetta; Cámara-Artigas, Ana; Abián, Olga; Velázquez-Campoy, Adrián

2018-02-01

The phosphotransferase system (PTS) controls the preferential use of sugars in bacteria and it is also involved in other processes, such as chemotaxis. It is formed by a protein cascade in which the first two proteins are general (namely, EI and HPr) and the others are sugar-specific permeases. The Rsd protein binds specifically to the RNA polymerase (RNAP) σ 70 factor. We first characterized the conformational stability of Escherichia coli Rsd. And second, we delineated the binding regions of Streptomyces coelicolor, HPr sc , and E. coli Rsd, by using fragments derived from each protein. To that end, we used several biophysical probes, namely, fluorescence, CD, NMR, ITC and BLI. Rsd had a free energy of unfolding of 15 kcal mol -1 at 25 °C, and a thermal denaturation midpoint of 103 °C at pH 6.5. The affinity between Rsd and HPr sc was 2 μM. Interestingly enough, the isolated helical-peptides, comprising the third (RsdH3) and fourth (RsdH4) Rsd helices, also interacted with HPr sc in a specific manner, and with affinities similar to that of the whole Rsd. Moreover, the isolated peptide of HPr sc , HPr 9-30 , comprising the active site, His15, also was bound to intact Rsd with similar affinity. Therefore, binding between Rsd and HPr sc was modulated by the two helices H3 and H4 of Rsd, and the regions around the active site of HPr sc . This implies that specific fragments of Rsd and HPr sc can be used to interfere with other protein-protein interactions (PPIs) of each other protein. Copyright © 2018 Elsevier Inc. All rights reserved.

Microscale chemistry-based design of eco-friendly, reagent-saving and efficient pharmaceutical analysis: a miniaturized Volhard's titration for the assay of sodium chloride.

PubMed

Rojanarata, Theerasak; Sumran, Krissadecha; Nateetaweewat, Paksupang; Winotapun, Weerapath; Sukpisit, Sirarat; Opanasopit, Praneet; Ngawhirunpat, Tanasait

2011-09-15

This work demonstrates the extended application of microscale chemistry which has been used in the educational discipline to the real analytical purposes. Using Volhard's titration for the determination of sodium chloride as a paradigm, the reaction was downscaled to less than 2 mL conducted in commercially available microcentrifuge tubes and using micropipettes for the measurement and transfer of reagents. The equivalence point was determined spectrophotometrically on the microplates which quickened the multi-sample measurements. After the validation and evaluation with bulk and dosage forms, the downsized method showed good accuracy comparable to the British Pharmacopeial macroscale method and gave satisfactory precision (intra-day, inter-day, inter-analyst and inter-equipment) with the relative standard deviation of less than 0.5%. Interestingly, the amount of nitric acid, silver nitrate, ferric alum and ammonium thiocyanate consumed in the miniaturized titration was reduced by the factors of 25, 50, 50 and 215 times, respectively. The use of environmentally dangerous dibutyl phthalate was absolutely eliminated in the proposed method. Furthermore, the release of solid waste silver chloride was drastically reduced by about 25 folds. Therefore, microscale chemistry is an attractive, facile and powerful green strategy for the development of eco-friendly, safe, and cost-effective analytical methods suitable for a sustainable environment. Copyright © 2011 Elsevier B.V. All rights reserved.

Development and validation of a generic high-performance liquid chromatography for the simultaneous separation and determination of six cough ingredients: Robustness study on core-shell particles.

PubMed

Yehia, Ali Mohamed; Essam, Hebatallah Mohamed

2016-09-01

A generally applicable high-performance liquid chromatographic method for the qualitative and quantitative determination of pharmaceutical preparations containing phenylephrine hydrochloride, paracetamol, ephedrine hydrochloride, guaifenesin, doxylamine succinate, and dextromethorphan hydrobromide is developed. Optimization of chromatographic conditions was performed for the gradient elution using different buffer pH values, flow rates and two C18 stationary phases. The method was developed using a Kinetex® C18 column as a core-shell stationary phase with a gradient profile using buffer pH 5.0 and acetonitrile at 2.0 mL/min flow rate. Detection was carried out at 220 nm and linear calibrations were obtained for all components within the studied ranges. The method was fully validated in agreement with ICH guidelines. The proposed method is specific, accurate and precise (RSD% < 3%). Limits of detection are lower than 2.0 μg/mL. Qualitative and quantitative responses were evaluated using experimental design to assist the method robustness. The method was proved to be highly robust against 10% change in buffer pH and flow rate (RSD% < 10%), however, the flow rate may significantly influence the quantitative responses of phenylephrine, paracetamol, and doxylamine (RSD% > 10%). Satisfactory results were obtained for commercial combinations analyses. Statistical comparison between the proposed chromatographic and official methods revealed no significant difference. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tellarini, Matteo; Ross, Ashley J.; Wands, David

Measurements of the non-Gaussianity of the primordial density field have the power to considerably improve our understanding of the physics of inflation. Indeed, if we can increase the precision of current measurements by an order of magnitude, a null-detection would rule out many classes of scenarios for generating primordial fluctuations. Large-scale galaxy redshift surveys represent experiments that hold the promise to realise this goal. Thus, we model the galaxy bispectrum and forecast the accuracy with which it will probe the parameter f {sub NL}, which represents the degree of primordial local-type non Gaussianity. Specifically, we address the problem of modellingmore » redshift space distortions (RSD) in the tree-level galaxy bispectrum including f {sub NL}. We find novel contributions associated with RSD, with the characteristic large scale amplification induced by local-type non-Gaussianity. These RSD effects must be properly accounted for in order to obtain un-biased measurements of f {sub NL} from the galaxy bispectrum. We propose an analytic template for the monopole which can be used to fit against data on large scales, extending models used in the recent measurements. Finally, we perform idealised forecasts on σ {sub f} {sub N{sub L}}—the accuracy of the determination of local non-linear parameter f {sub NL}—from measurements of the galaxy bispectrum. Our findings suggest that current surveys can in principle provide f {sub NL} constraints competitive with Planck , and future surveys could improve them further.« less

Simultaneous Quantitative Determination of 12 Active Components in Yuanhu Zhitong Prescription by RP-HPLC Coupled with Photodiode Array Detection

PubMed Central

Zhang, Xiaokai; Zhang, Song; Yang, Qian; Cao, Wei; Xie, Yanhua; Qiu, Pengcheng; Wang, Siwang

2015-01-01

Background: Yuanhu Zhitong prescription (YZP) is a famous traditional Chinese medicine formula, which is officially recorded in Chinese Pharmacopoeia for the treatment of stomach pain, hypochondriac pain, headache and dysmenorrhea caused by qi-stagnancy and blood stasis. It is the first report for the simultaneous determination of 12 active components in YZP. Objective: A newly, simple, accurate and reliable method for the separation and determination of 12 active components (protopine, α-allocryptopine, coptisine, xanthotol, palmatine, dehydrocorydaline, glaucine, tetrahydropalmatine, tetrahydroberberine, imperatorin, corydaline, isoimperatorin) in YZP was developed and validated using HPLC-PAD. Materials and Methods: The analytes were performed on a Phenomenex Luna-C18 (2) column (250×4.6 mm, 5.0 μm) with a gradient elution program using a mixture of acetonitrile and 0.1% phosphoric acid water solution (adjusted with triethylamine to pH 5.6) as mobile phase. Analytes were performed at 30°C with a flow rate of 1.0 mL/min. Results: The validated method was applied to analyze four major dosage forms of YZP coming from different manufacturers with good linearity (r2, 0.9981~0.9999), precision (RSD, 0.24~2.89%), repeatability (RSD, 0.15~3.34%), stability (RSD, 0.14~3.35%), recovery (91.13~110.81%) of the 12 components. Conclusion: The proposed method enables the separation and determination of 12 active components in a single run for the quality control of YZP. PMID:25709212

Determination of caprolactam and 6-aminocaproic acid in human urine using hydrophilic interaction liquid chromatography-tandem mass spectrometry.

PubMed

Wu, Ya-Hsueh; Wu, Ming-Ling; Lin, Chun-Chi; Chu, Wei-Lan; Yang, Chen-Chang; Lin, Robert Tate; Deng, Jou-Fang

2012-02-15

A simple and rapid assay based on hydrophilic interaction liquid chromatography with tandem mass spectrometry has been first developed and validated for simultaneous determination of caprolactam (CA) and 6-aminocaproic acid (6-ANCA) in human urine using 8-aminocaprylic acid as internal standard. A 20μL aliquot of urine was injected directly into the liquid chromatography tandem mass spectrometry (LC-MS-MS) system. The analytes were separated on a Phenomenex Luna HILIC column with gradient elution. Detection was performed on Triple Quadrupole LC-MS in positive ions multiple reaction monitoring mode using electrospray ionization. The calibration curves were linear (r(2)≥0.995) over the concentration range from 62.5 to 1250ng/mL for CA and 31.25 to 1000ng/mL for 6-ANCA. The detection limits of CA and 6-ANCA were 62.5 and 15.6ng/mL, respectively. The intra-day and inter-day precisions were within 8.7% and 9.9%, respectively. The intra-day and inter-day accuracy were between 5.3% and 3.5%, and between 6.1% and 6.6%, respectively. The method proved to be simple and time efficient, and was successfully applied to evaluate the kinetics of caprolactam in one unusual case of caprolactam poisoning. Copyright © 2011 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patikoglou,G.; Westblade, L.; Campbell, E.

The Escherichia coli Rsd protein binds tightly and specifically to the RNA polymerase (RNAP) {sigma}{sup 70} factor. Rsd plays a role in alternative {sigma} factor-dependent transcription by biasing the competition between {sigma}{sup 70} and alternative {sigma} factors for the available core RNAP. Here, we determined the 2.6 {angstrom}-resolution X-ray crystal structure of Rsd bound to {sigma}{sup 70} domain 4 ({sigma}{sup 70}{sub 4}), the primary determinant for Rsd binding within {sigma}{sup 70}. The structure reveals that Rsd binding interferes with the two primary functions of {sigma}{sup 70}{sub 4}, core RNAP binding and promoter -35 element binding. Interestingly, the most highly conservedmore » Rsd residues form a network of interactions through the middle of the Rsd structure that connect the {sigma}{sup 70}{sub 4}-binding surface with three cavities exposed on distant surfaces of Rsd, suggesting functional coupling between {sigma}{sup 70}{sub 4} binding and other binding surfaces of Rsd, either for other proteins or for as yet unknown small molecule effectors. These results provide a structural basis for understanding the role of Rsd, as well as its ortholog, AlgQ, a positive regulator of Pseudomonas aeruginosa virulence, in transcription regulation.« less

Simultaneous determination of four neuroprotective compounds of Tilia amurensis by high performance liquid chromatography coupled with diode array detector

PubMed Central

Lee, Bohyung; Weon, Jin Bae; Yun, Bo-Ra; Lee, Jiwoo; Eom, Min Rye; Ma, Choong Je

2014-01-01

Background: Tilia amurensis consists of various compounds, such as flavonoids and terpenoids. Objective: A simple and reliable high performance liquid chromatography (HPLC) coupled with the diode array detector (DAD) method has been established for simultaneous determination of epicatechin, nudiposide, lyoniside, and scopoletin isolated from Tilia amurensis. Materials and Methods: Optimum separations were obtained with a SHISEIDO C18 column by gradient eluton, with 0.1% Trifluoroacetic acid (TFA) water-methanol as the mobile phase. The gradient elution system was completed within 40 minutes. The flow rate and detection wavelength were 1 mL/minute, 205 nm, 250 nm, and 280 nm, respectively. Results: Validation of the analytical method was evaluated by linearity, precision, and the accuracy test. The calibration curve was linear over the established range with R2 > 0.997. The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.01-15.20 μg/mL and 0.03-46.06 μg/mL. The method exhibited an intraday and interday precision range of 96.25-105.66% and 93.52-109.92%, respectively (RSD <2.80%). The recoveries and relative standard deviation (RSD) of the four compounds in Tilia amurensis were in the range of 90.42-104.84% and 0.2-2.58%. Conclusion: This developed method was accurate and reliable for the quality evaluation of the four compounds isolated from Tilia amurensis. PMID:25210303

Multiresidue pesticide analysis of tuber and root commodities by QuEchERS extraction and ultra-performance liquid chromatography coupled to tandem mass spectrometry.

PubMed

Garrido Frenich, Antonia; Martín Fernández, María del Mar; Díaz Moreno, Laura; Martínez Vidal, Jose Lúis; López-Gutiérrez, Noelia

2012-01-01

A simple, rapid, and reliable multiresidue method to determine 84 pesticides in potato and carrot samples by ultra-performance liquid chromatography coupled to MS/MS has been developed and fully validated for routine analysis according to ISO/IEC 17025:2005. The method makes use of a buffered Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) sample preparation procedure based on a single extraction with acidified acetonitrile, followed by partitioning with salts. Chromatographic conditions were optimized in order to achieve a rapid separation in the multiple reaction monitoring mode. Performance characteristics of the method, including an estimation of measurement uncertainty using validation data, are reported for both matrixes. Calibration curves were linear from 0.010 to 0.150 mg/kg for most compounds. The LOD and LOQ were 0.006 and 0.010 mg/kg, respectively, except for fluorocloridone, fluquinconazol, and hexitiazox, which were 0.030 and 0.050 mg/kg, respectively. Recoveries obtained were in the range 70-116%, with intraday precision values < or = 20% RSD and interday precision values < or = 25% RSD at two different concentration levels. The overall uncertainty of the method was estimated at two concentrations as being lower than 34% in all cases. The method has been applied to the analysis of 70 vegetable samples, and imidacloprid and linuron were the pesticides most frequently found in potato and carrot commodities, respectively.

High-throughput quantitative analysis by desorption electrospray ionization mass spectrometry.

PubMed

Manicke, Nicholas E; Kistler, Thomas; Ifa, Demian R; Cooks, R Graham; Ouyang, Zheng

2009-02-01

A newly developed high-throughput desorption electrospray ionization (DESI) source was characterized in terms of its performance in quantitative analysis. A 96-sample array, containing pharmaceuticals in various matrices, was analyzed in a single run with a total analysis time of 3 min. These solution-phase samples were examined from a hydrophobic PTFE ink printed on glass. The quantitative accuracy, precision, and limit of detection (LOD) were characterized. Chemical background-free samples of propranolol (PRN) with PRN-d(7) as internal standard (IS) and carbamazepine (CBZ) with CBZ-d(10) as IS were examined. So were two other sample sets consisting of PRN/PRN-d(7) at varying concentration in a biological milieu of 10% urine or porcine brain total lipid extract, total lipid concentration 250 ng/microL. The background-free samples, examined in a total analysis time of 1.5 s/sample, showed good quantitative accuracy and precision, with a relative error (RE) and relative standard deviation (RSD) generally less than 3% and 5%, respectively. The samples in urine and the lipid extract required a longer analysis time (2.5 s/sample) and showed RSD values of around 10% for the samples in urine and 4% for the lipid extract samples and RE values of less than 3% for both sets. The LOD for PRN and CBZ when analyzed without chemical background was 10 and 30 fmol, respectively. The LOD of PRN increased to 400 fmol analyzed in 10% urine, and 200 fmol when analyzed in the brain lipid extract.

Development of a simultaneous multiple solid-phase microextraction-single shot-gas chromatography/mass spectrometry method and application to aroma profile analysis of commercial coffee.

PubMed

Lee, Changgook; Lee, Younghoon; Lee, Jae-Gon; Buglass, Alan J

2013-06-21

A simultaneous multiple solid-phase microextraction-single shot-gas chromatography mass spectrometry (smSPME-ss-GC/MS) method has been developed for headspace analysis. Up to four fibers (50/30 μm DVB/CAR/PDMS) were used simultaneously for the extraction of aroma components from the headspace of a single sample chamber in order to increase sensitivity of aroma extraction. To avoid peak broadening and to maximize resolution, a simple cryofocusing technique was adopted during sequential thermal desorption of multiple SPME fibers prior to a 'single shot' chromatographic run. The method was developed and validated on a model flavor mixture, containing 81 known pure components. With the conditions of 10 min of incubation and 30 min of extraction at 50 °C, single, dual, triple and quadruple SPME extractions were compared. The increase in total peak area with increase in the number of fibers showed good linearity (R(2)=0.9917) and the mean precision was 12.0% (RSD) for the total peak sum, with quadruple simultaneous SPME extraction. Using a real sample such as commercial coffee granules, aroma profile analysis was conducted using single, dual, triple and quadruple SPME fibers. The increase in total peak intensity again showed good linearity with increase in the number of SPME fibers used (R(2)=0.9992) and the precision of quadruple SPME extraction was 9.9% (RSD) for the total peak sum. Copyright © 2013 Elsevier B.V. All rights reserved.

Novel approaches to analysis by flow injection gradient titration.

PubMed

Wójtowicz, Marzena; Kozak, Joanna; Kościelniak, Paweł

2007-09-26

Two novel procedures for flow injection gradient titration with the use of a single stock standard solution are proposed. In the multi-point single-line (MP-SL) method the calibration graph is constructed on the basis of a set of standard solutions, which are generated in a standard reservoir and subsequently injected into the titrant. According to the single-point multi-line (SP-ML) procedure the standard solution and a sample are injected into the titrant stream from four loops of different capacities, hence four calibration graphs are able to be constructed and the analytical result is calculated on the basis of a generalized slope of these graphs. Both approaches have been tested on the example of spectrophotometric acid-base titration of hydrochloric and acetic acids with using bromothymol blue and phenolphthalein as indicators, respectively, and sodium hydroxide as a titrant. Under optimized experimental conditions the analytical results of precision less than 1.8 and 2.5% (RSD) and of accuracy less than 3.0 and 5.4% (relative error (RE)) were obtained for MP-SL and SP-ML procedures, respectively, in ranges of 0.0031-0.0631 mol L(-1) for samples of hydrochloric acid and of 0.1680-1.7600 mol L(-1) for samples of acetic acid. The feasibility of both methods was illustrated by applying them to the total acidity determination in vinegar samples with precision lower than 0.5 and 2.9% (RSD) for MP-SL and SP-ML procedures, respectively.

Development and validation of an improved method for the determination of chloropropanols in paperboard food packaging by GC-MS.

PubMed

Mezouari, S; Liu, W Yun; Pace, G; Hartman, T G

2015-01-01

The objective of this study was to develop an improved analytical method for the determination of 3-chloro-1,2-propanediol (3-MCPD) and 1,3-dichloropropanol (1,3-DCP) in paper-type food packaging. The established method includes aqueous extraction, matrix spiking of a deuterated surrogate internal standard (3-MCPD-d₅), clean-up using Extrelut solid-phase extraction, derivatisation using a silylation reagent, and GC-MS analysis of the chloropropanols as their corresponding trimethyl silyl ethers. The new method is applicable to food-grade packaging samples using European Commission standard aqueous extraction and aqueous food stimulant migration tests. In this improved method, the derivatisation procedure was optimised; the cost and time of the analysis were reduced by using 10 times less sample, solvents and reagents than in previously described methods. Overall the validation data demonstrate that the method is precise and reliable. The limit of detection (LOD) of the aqueous extract was 0.010 mg kg(-1) (w/w) for both 3-MCPD and 1,3-DCP. Analytical precision had a relative standard deviation (RSD) of 3.36% for 3-MCPD and an RSD of 7.65% for 1,3-DCP. The new method was satisfactorily applied to the analysis of over 100 commercial paperboard packaging samples. The data are being used to guide the product development of a next generation of wet-strength resins with reduced chloropropanol content, and also for risk assessments to calculate the virtual safe dose (VSD).

Development of a high-performance liquid chromatography method for the determination of florfenicol in animal feedstuffs.

PubMed

Yang, JinJing; Sun, GuiZhi; Qian, MingRong; Huang, LingLi; Ke, XianBing; Yang, Bo

2017-11-15

An effective thin layer chromatography (TLC) purification procedure coupled to high-performance liquid chromatography (HPLC) method was developed for the determination of florfenicol (FF) in pig, chicken and fish feedstuffs. The feedstuff samples were extracted with ethyl acetate, defatted with n-hexane saturated with acetonitrile, and further purified by TLC. The chromatographic separation was performed on a Waters Symmetry C 18 column using an isocratic procedure with acetonitrile-water (35:65, v/v) at 0.6mL/min. The ultraviolet (UV) detector was set at a wavelength of 225nm. The FF concentrations in feedstuff samples were quantified using a standard curve. Good linear correlations (y=159075x-15054, r>0.9999) were achieved within the concentration range of 0.05-200μg/mL. The recoveries of FF spiked at levels of 1, 100 and 1000μg/g ranged from 80.6% to 105.3% with the intra-day and inter-day relative standard deviation (RSD) less than 9.3%. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.02 and 0.06mg/kg for pig feedstuffs, 0.02 and 0.07mg/kg for chicken feedstuffs, and 0.02 and 0.05mg/kg for fish feedstuffs, respectively. This reliable, simple and cost-effective method could be applied to the routine monitoring of FF in animal feedstuffs. Copyright © 2017 Elsevier B.V. All rights reserved.

Molecularly imprinted coated graphene oxide solid-phase extraction monolithic capillary column for selective extraction and sensitive determination of phloxine B in coffee bean.

PubMed

Zhai, Haiyun; Su, Zihao; Chen, Zuanguang; Liu, Zhenping; Yuan, Kaisong; Huang, Lu

2015-03-20

A method was developed to sensitively determine phloxine B in coffee bean by molecularly imprinted polymers (MIPs) coated graphene oxide (GO) solid-phase extraction (GO-MISPE) coupled with high-performance liquid chromatography and laser-induced fluorescence detection (HPLC-LIF). The GO-MISPE capillary monolithic column was prepared by water-bath in situ polymerization, using GO as supporting material, phloxine B, methacrylic acid (MAA), and ethylene dimethacrylate (EDMA) as template, functional monomer, and cross-linker, respectively. The properties of the homemade GO-MISPE capillary monolithic column, including capacity and specificity, were investigated under optimized conditions. The GO-MIPs were characterized by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR). The mean recoveries of phloxine B in coffee bean ranged from 89.5% to 91.4% and the intra-day and inter-day relative standard deviation (RSD) values all ranged from 3.6% to 4.7%. Good linearity was obtained over 0.001-2.0 μg mL(-1) (r=0.9995) with the detection limit (S/N=3) of 0.075 ng mL(-1). Under the selected conditions, enrichment factors of over 90-fold were obtained and extraction on the monolithic column effectively cleaned up the coffee bean matrix. The results demonstrated that the proposed GO-MISPE HPLC-LIF method can be applied to sensitively determine phloxine B in coffee bean. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparative analysis of Sambucus nigra and Sambucus australis flowers: development and validation of an HPLC method for raw material quantification and preliminary stability study.

PubMed

Scopel, Marina; Mentz, Lílian Auler; Henriques, Amélia Teresinha

2010-07-01

This work was designed to develop a simple, effective, and reliable LC system to identify a chemical marker and compare Sambucus nigra L. and Sambucus australis Cham. et Schltdl. flower extracts (American and European elder). Rutin was the main constituent of both species. The developed method showed a linear response in the range of 10 to 45 microg x mL(-1) for rutin and 1.75 to 3.25 microg x mL(-1) for samples of the Sambucus species. Precision was determined and the relative standard deviations were 1.75 % for HSN and 1.28 % for HSA for intraday precision and 1.28 % and 1.51 % for inter-day precision, respectively, while accuracy was 97.9 % for HSN and 99.41 % for HSA. Quantification and detection limits as well as robustness were determined, presenting adequate results. The LC method showed an adequate performance for the separation of flavonoid glycosides in S. nigra and S. australis extracts, since the presence of interference had been previously evaluated. The analysis of thirty different samples of S. NIGRA and S. australis of different origins did not show significant variability among them. An accelerated stability study revealed a significant decrease in the first 30 days reaching 57 % in 90 days for S. australis samples and a total decrease of 25 % in 90 days for S. nigra samples, considering rutin as the chemical marker. These results will contribute to quality control analysis routines of these raw materials in pharmaceutical production facilities. Georg Thieme Verlag KG Stuttgart.New York.

[The development and validation of the methods for the quantitative determination of sibutramine derivatives in dietary supplements].

PubMed

Stern, K I; Malkova, T L

The objective of the present study was the development and validation of sibutramine demethylated derivatives, desmethyl sibutramine and didesmethyl sibutramine. Gas-liquid chromatography with the flame ionization detector was used for the quantitative determination of the above substances in dietary supplements. The conditions for the chromatographic determination of the analytes in the presence of the reference standard, methyl stearate, were proposed allowing to achieve the efficient separation. The method has the necessary sensitivity, specificity, linearity, accuracy, and precision (on the intra-day and inter-day basis) which suggests its good validation characteristics. The proposed method can be employed in the analytical laboratories for the quantitative determination of sibutramine derivatives in biologically active dietary supplements.

QuEChERS-based purification method coupled to ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to determine six quaternary ammonium compounds (QACs) in dairy products.

PubMed

Xian, Yanping; Dong, Hao; Wu, Yuluan; Guo, Xindong; Hou, Xiangchang; Wang, Bin

2016-12-01

QuEChERS-based purification coupled with UPLC-MS/MS method, was developed for six quaternary ammonium compounds (QACs) determination in dairy products. Powder samples were firstly dispersed by water. Protein in liquid milk was precipitated and sample solution was extracted by acetonitrile. QuEChERS-based purification was used to purify the solution. QACs were finally separated by HILIC column and detected in MRM mode of MS/MS under ESI(+). The stable isotope benzyl-2,3,4,5,6-d5-dimethyltetradecylammonium bromide (C14-BAC-d5) was used as an internal standard. This method was validated in terms of linearity, sensitivity, precision, accuracy. Linear relations were favorable for QACs over the selected concentration ranges of 0.2-50μg/L, with correlation coefficients greater than 0.999. The limits of detection (LODs) were in the range of 0.4-14.5μg/kg. Recoveries were between 91.2% and 115% with RSDs of 2.8-7.5% for intra-day precision and 3.7-6.7% for inter-day precision. This validated method was successfully applied to determine the QACs concentrations in dairy products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Extraction protocol and liquid chromatography/tandem mass spectrometry method for determining micelle-entrapped paclitaxel at the cellular and subcellular levels: Application to a cellular uptake and distribution study.

PubMed

Zheng, Nan; Lian, Bin; Du, Wenwen; Xu, Guobing; Ji, Jiafu

2018-01-01

Paclitaxel-loaded polymeric micelles (PTX-PM) are commonly used as tumor-targeted nanocarriers and display outstanding antitumor features in clinic, but its accumulation and distribution in vitro are lack of investigation. It is probably due to the complex micellar system and its low concentration at the cellular or subcellular levels. In this study, we developed an improved extraction method, which was a combination of mechanical disruption and liquid-liquid extraction (LLE), to extract the total PTX from micelles in the cell lysate and subcellular compartments. An ultra-performance liquid chromatography tandem mass spectroscopy (UPLC-MS/MS) method was optimized to detect the low concentration of PTX at cellular and subcellular levels simultaneously, using docetaxel as internal standard (IS). The method was proved to release PTX totally from micelles (≥95.93%) with a consistent and reproducible extraction recovery (≥75.04%). Good linearity was obtained at concentrations ranging from 0.2 to 20ng/mL. The relative error (RE%) for accuracy varied from 0.68 to 7.56%, and the intra- and inter-precision (relative standard deviation, RSD%) was less than 8.64% and 13.14%, respectively. This method was fully validated and successfully applied to the cellular uptake and distribution study of PTX-loaded PLGA-PEG micelles in human breast cancer cells (MCF-7). Copyright © 2017 Elsevier B.V. All rights reserved.

Validation of a spectrophotometric assay method for bisoprolol using picric acid.

PubMed

Panainte, Alina-Diana; Bibire, Nela; Tântaru, Gladiola; Apostu, M; Vieriu, Mădălina

2013-01-01

Bisoprolol is a drug belonging to beta blockers drugs used primarily for the treatment of cardiovascular diseases. A spectrophotometric method for quantitative determination of bisoprolol was developed based on the formation of a complex combination between bisoprolol and picric acid. The complex combination of bisoprolol and picric acid has a maximum absorbance peak at 420 nm. Optimum working conditions were established and the method was validated. The method presented a good linearity in the concentration range 5-120 microg/ml (regression coefficient r2 = 0.9992). The RSD for the precision of the method was 1.74 and for the intermediate precision 1.43, and recovery values ranged between 98.25-101.48%. The proposed and validated spectrophotometric method for the determination of bisoprolol is simple and cost effective.

Transcriptional organization and in vivo role of the Escherichia coli rsd gene, encoding the regulator of RNA polymerase sigma D.

PubMed

Jishage, M; Ishihama, A

1999-06-01

The regulator of sigma D (Rsd) was identified as an RNA polymerase sigma70-associated protein in stationary-phase Escherichia coli with the inhibitory activity of sigma70-dependent transcription in vitro (M. Jishage and A. Ishihama, Proc. Natl. Acad. Sci. USA 95:4953-4958, 1998). Primer extension analysis of rsd mRNA indicated the presence of two promoters, sigmaS-dependent P1 and sigma70-dependent P2 with the gearbox sequence. To get insight into the in vivo role of Rsd, the expression of a reporter gene fused to either the sigma70- or sigmaS-dependent promoter was analyzed in the absence of Rsd or the presence of overexpressed Rsd. In the rsd null mutant, the sigma70- and sigmaS-dependent gene expression was increased or decreased, respectively. On the other hand, the sigma70- or sigmaS-dependent transcription was reduced or enhanced, respectively, after overexpression of Rsd. The repression of the sigmaS-dependent transcription in the rsd mutant is overcome by increased production of the sigmaS subunit. Together these observations support the prediction that Rsd is involved in replacement of the RNA polymerase sigma subunit from sigma70 to sigmaS during the transition from exponential growth to the stationary phase.

Changes in the soil microbial community after reductive soil disinfestation and cucumber seedling cultivation.

PubMed

Huang, Xinqi; Liu, Liangliang; Wen, Teng; Zhang, Jinbo; Wang, Fenghe; Cai, Zucong

2016-06-01

Reductive soil disinfestation (RSD) has been proven to be an effective and environmentally friendly way to control many soilborne pathogens and diseases. In this study, the RSDs using ethanol (Et-RSD) and alfalfa (Al-RSD) as organic carbons were performed in a Rhizoctonia solani-infected soil, and the dissimilarities of microbial communities during the RSDs and after planting two seasons of cucumber seedlings in the RSDs-treated soil were respectively investigated by MiSeq pyrosequencing. The results showed that, as for bacteria, Coprococcus, Flavisolibacter, Rhodanobacter, Symbiobacterium, and UC-Ruminococcaceae became the dominant bacterial genera at the end of Al-RSD. In contrast, Et-RSD soil involved more bacteria belonging to Firmicutes, such as Sedimentibacter, UC-Gracilibacteraceae, and Desulfosporosinus. For fungi, Chaetomium significantly increased at the end of RSDs, while Rhizoctonia and Aspergillus significantly decreased. After planting two seasons of cucumber seedlings, those bacteria belonging to Firmicutes significantly decreased, but Lysobacter and Rhodanobacter belonging to the phylum Proteobacteria as well as UC-Sordariales and Humicola belonging to Ascomycota alternatively increased in Al- and Et-RSD-treated soils. Besides, some nitrification, denitrification, and nitrogen fixation genes were apparently increased in the RSD-treated soils, but the effect was more profound in Al-RSD than Et-RSD. Overall, Et-RSD could induced more antagonists belonging to Firmicutes under anaerobic condition, whereas Al-RSD could continuously stimulate some functional microorganisms (Lysobacter and Rhodanobacter) and further improve nitrogen transformation activities in the soil at the coming cropping season.

Interlaboratory validation of quantitative duplex real-time PCR method for screening analysis of genetically modified maize.

PubMed

Takabatake, Reona; Koiwa, Tomohiro; Kasahara, Masaki; Takashima, Kaori; Futo, Satoshi; Minegishi, Yasutaka; Akiyama, Hiroshi; Teshima, Reiko; Oguchi, Taichi; Mano, Junichi; Furui, Satoshi; Kitta, Kazumi

2011-01-01

To reduce the cost and time required to routinely perform the genetically modified organism (GMO) test, we developed a duplex quantitative real-time PCR method for a screening analysis simultaneously targeting an event-specific segment for GA21 and Cauliflower Mosaic Virus 35S promoter (P35S) segment [Oguchi et al., J. Food Hyg. Soc. Japan, 50, 117-125 (2009)]. To confirm the validity of the method, an interlaboratory collaborative study was conducted. In the collaborative study, conversion factors (Cfs), which are required to calculate the GMO amount (%), were first determined for two real-time PCR instruments, the ABI PRISM 7900HT and the ABI PRISM 7500. A blind test was then conducted. The limit of quantitation for both GA21 and P35S was estimated to be 0.5% or less. The trueness and precision were evaluated as the bias and reproducibility of the relative standard deviation (RSD(R)). The determined bias and RSD(R) were each less than 25%. We believe the developed method would be useful for the practical screening analysis of GM maize.

Development of high-throughput and high sensitivity capillary gel electrophoresis platform method for Western, Eastern, and Venezuelan equine encephalitis (WEVEE) virus like particles (VLPs) purity determination and characterization.

PubMed

Gollapudi, Deepika; Wycuff, Diane L; Schwartz, Richard M; Cooper, Jonathan W; Cheng, K C

2017-10-01

In this paper, we describe development of a high-throughput, highly sensitive method based on Lab Chip CGE-SDS platform for purity determination and characterization of virus-like particle (VLP) vaccines. A capillary gel electrophoresis approach requiring about 41 s per sample for analysis and demonstrating sensitivity to protein initial concentrations as low as 20 μg/mL, this method has been used previously to evaluate monoclonal antibodies, but this application for lot release assay of VLPs using this platform is unique. The method was qualified and shown to be accurate for the quantitation of VLP purity. Assay repeatability was confirmed to be less than 2% relative standard deviation of the mean (% RSD) with interday precision less than 2% RSD. The assay can evaluate purified VLPs in a concentration range of 20-249 μg/mL for VEE and 20-250 μg/mL for EEE and WEE VLPs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of the presence of β-hydroxy-β-methylbutyric acid and α-hydroxyisocaproic acid in bovine whole milk and fermented dairy products by a validated liquid chromatography-mass spectrometry method.

PubMed

Ehling, Stefan; Reddy, Todime M

2014-02-19

A simple, rugged, quantitative, and confirmatory method based on liquid chromatography-mass spectrometry was developed and comprehensively validated for the analysis of the leucine metabolites β-hydroxy-β-methylbutyric acid (HMB) and α-hydroxyisocaproic acid (HICA) in bovine whole milk and yogurt. Mean accuracy (90-110% for HMB and 85-115% for HICA) and total precision (<10% RSD in most cases, except for <20% RSD for HMB at the limit of quantitation) at four concentration levels across three validation runs have been determined. Limits of quantitation for HMB and HICA in whole milk were 20 and 5 μg/L, respectively. Measured concentrations of HMB and HICA were <20-29 and 32-37 μg/L, respectively, in bovine whole milk and <5 and 3.0-15.2 mg/L, respectively, in yogurt. These concentrations are insufficient by large margins to deliver any musculoskeletal benefits, and fortification of milk and dairy products with HMB and/or HICA appears to be justified.

Rapid Analysis of Trace Drugs and Metabolites Using a Thermal Desorption DART-MS Configuration.

PubMed

Sisco, Edward; Forbes, Thomas P; Staymates, Matthew E; Gillen, Greg

2016-01-01

The need to analyze trace narcotic samples rapidly for screening or confirmatory purposes is of increasing interest to the forensic, homeland security, and criminal justice sectors. This work presents a novel method for the detection and quantification of trace drugs and metabolites off of a swipe material using a thermal desorption direct analysis in real time mass spectrometry (TD-DART-MS) configuration. A variation on traditional DART, this configuration allows for desorption of the sample into a confined tube, completely independent of the DART source, allowing for more efficient and thermally precise analysis of material present on a swipe. Over thirty trace samples of narcotics, metabolites, and cutting agents deposited onto swipes were rapidly differentiated using this methodology. The non-optimized method led to sensitivities ranging from single nanograms to hundreds of picograms. Direct comparison to traditional DART with a subset of the samples highlighted an improvement in sensitivity by a factor of twenty to thirty and an increase in reproducibility sample to sample from approximately 45 % RSD to less than 15 % RSD. Rapid extraction-less quantification was also possible.

Synthesis and characterization of a molecularly imprinted polymer for the determination of trace tributyltin in seawater and seafood by liquid chromatography-tandem mass spectroscopy.

PubMed

Zhu, Shanshan; Hu, Futao; Yang, Ting; Gan, Ning; Pan, Daodong; Cao, Yuting; Wu, Dazhen

2013-03-15

Analysis of tributyltin chloride (TBT) in environmental samples, such as seawater, is important in order to evaluate the TBT contamination and accumulation in the trophic chain. The environmental impact of organotin compounds has been a particular focus of analytical studies. The present study reports the use of molecular imprinting technology coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine trace amounts of TBT in seawater and seafood (mussel tissue samples). The imprinted polymer was synthesized by a non-covalent free-radical approach using acrylamide (AM) as a monomer and TBT as a template molecule in acetonitrile solvent (polymerization media). The imprinted polymer synthesized by this approach exhibited good adsorptive capacity and allowed specific retention of TBT. Recoveries of TBT in seawater samples spiked with different TBT concentrations ranged from 67.2% to 81.1% with peak area precision (RSD)<3.7%, and recoveries of TBT in mussel tissue samples ranged from 75.0% to 94.2% with RSD<4.8%. Copyright © 2013 Elsevier B.V. All rights reserved.

On-line Determination of Zinc in Water and Biological Samples after Its Preconcentration onto Zincon Anchored Polyurethane Foam.

PubMed

Azeem, Sami M Abdel; Hanafi, Hassan A; El-Shahat, M F

2015-01-01

A fast and sensitive on-line procedure for the determination of zinc in water and biological samples was developed. Zinc was preconcentrated in a mini-column packed with polyurethane foam (PUF) chemically modified with zincon via -N=N- bonding. The optimal conditions for preconcentration were pH 8.5 and sample flow rate of 4.0 mL min(-1). Quantitative desorption of Zn(II) was obtained by 0.1 mol L(-1) hydrochloric acid and subsequent spectrophotmetric determination using 4-(2-pyridylazo)-resorcinol at 498 nm. The obtained detection limit was found to be 3.0 ng mL(-1), precision (RSD) was 4.8 and 6.7% at 20 and 110 ng mL(-1), respectively, for 60 s preconcentration time and enrichment factor was 31. The linearity range was from 10 to 120 ng mL(-1) and maximum sample throughput was 20 h(-1). Finally, the method was successfully applied to the determination of zinc in tap water, Nile River water and human urine samples with RSD in the range of 1.1 - 8.3%.

The Escherichia coli regulator of sigma 70 protein, Rsd, can up-regulate some stress-dependent promoters by sequestering sigma 70.

PubMed

Mitchell, Jennie E; Oshima, Taku; Piper, Sarah E; Webster, Christine L; Westblade, Lars F; Karimova, Gouzel; Ladant, Daniel; Kolb, Annie; Hobman, Jon L; Busby, Stephen J W; Lee, David J

2007-05-01

The Escherichia coli Rsd protein forms complexes with the RNA polymerase sigma(70) factor, but its biological role is not understood. Transcriptome analysis shows that overexpression of Rsd causes increased expression from some promoters whose expression depends on the alternative sigma(38) factor, and this was confirmed by experiments with lac fusions at selected promoters. The LP18 substitution in Rsd increases the Rsd-dependent stimulation of these promoter-lac fusions. Analysis with a bacterial two-hybrid system shows that the LP18 substitution in Rsd increases its interaction with sigma(70). Our experiments support a model in which the role of Rsd is primarily to sequester sigma(70), thereby increasing the levels of RNA polymerase containing the alternative sigma(38) factor.

Automated GC-MS analysis of free amino acids in biological fluids.

PubMed

Kaspar, Hannelore; Dettmer, Katja; Gronwald, Wolfram; Oefner, Peter J

2008-07-15

A gas chromatography-mass spectrometry (GC-MS) method was developed for the quantitative analysis of free amino acids as their propyl chloroformate derivatives in biological fluids. Derivatization with propyl chloroformate is carried out directly in the biological samples without prior protein precipitation or solid-phase extraction of the amino acids, thereby allowing automation of the entire procedure, including addition of reagents, extraction and injection into the GC-MS. The total analysis time was 30 min and 30 amino acids could be reliably quantified using 19 stable isotope-labeled amino acids as internal standards. Limits of detection (LOD) and lower limits of quantification (LLOQ) were in the range of 0.03-12 microM and 0.3-30 microM, respectively. The method was validated using a certified amino acid standard and reference plasma, and its applicability to different biological fluids was shown. Intra-day precision for the analysis of human urine, blood plasma, and cell culture medium was 2.0-8.8%, 0.9-8.3%, and 2.0-14.3%, respectively, while the inter-day precision for human urine was 1.5-14.1%.

Stability indicating HPLC-UV method for detection of curcumin in Curcuma longa extract and emulsion formulation.

PubMed

Syed, Haroon Khalid; Liew, Kai Bin; Loh, Gabriel Onn Kit; Peh, Kok Khiang

2015-03-01

A stability-indicating HPLC-UV method for the determination of curcumin in Curcuma longa extract and emulsion was developed. The system suitability parameters, theoretical plates (N), tailing factor (T), capacity factor (K'), height equivalent of a theoretical plate (H) and resolution (Rs) were calculated. Stress degradation studies (acid, base, oxidation, heat and UV light) of curcumin were performed in emulsion. It was found that N>6500, T<1.1, K' was 2.68-3.75, HETP about 37 and Rs was 1.8. The method was linear from 2 to 200 μg/mL with a correlation coefficient of 0.9998. The intra-day precision and accuracy for curcumin were ⩽0.87% and ⩽2.0%, while the inter-day precision and accuracy values were ⩽2.1% and ⩽-1.92. Curcumin degraded in emulsion under acid, alkali and UV light. In conclusion, the stability-indicating method could be employed to determine curcumin in bulk and emulsions. Copyright © 2014 Elsevier Ltd. All rights reserved.

RP-HPLC Method Development and Validation for Determination of Eptifibatide Acetate in Bulk Drug Substance and Pharmaceutical Dosage Forms.

PubMed

Bavand Savadkouhi, Maryam; Vahidi, Hossein; Ayatollahi, Abdul Majid; Hooshfar, Shirin; Kobarfard, Farzad

2017-01-01

A new, rapid, economical and isocratic reverse phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of eptifibatide acetate, a small synthetic antiplatelet peptide, in bulk drug substance and pharmaceutical dosage forms. The developed method was validated as per of ICH guidelines. The chromatographic separation was achieved isocratically on C18 column (150 x 4.60 mm i.d., 5 µM particle size) at ambient temperature using acetonitrile (ACN), water and trifluoroacetic acid (TFA) as mobile phase at flow rate of 1 mL/min and UV detection at 275 nm. Eptifibatide acetate exhibited linearity over the concentration range of 0.15-2 mg/mL (r 2 =0.997) with limit of detection of 0.15 mg/mL The accuracy of the method was 96.4-103.8%. The intra-day and inter-day precision were between 0.052% and 0.598%, respectively. The present successfully validated method with excellent selectivity, linearity, sensitivity, precision and accuracy was applicable for the assay of eptifibatide acetate in bulk drug substance and pharmaceutical dosage forms.

Rapid determination of five antibiotic residues in swine wastewater by online solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Tagiri-Endo, Misako; Suzuki, Shigeru; Nakamura, Tomoyuki; Hatakeyama, Takashi; Kawamukai, Kazuo

2009-02-01

A simple and quick online solid-phase extraction (SPE) coupled to liquid chromatography (LC)/tandem mass spectrometry (MS/MS) for the determination of the five antibiotics (florfenicol, FF; lincomycin, LCM; oxytetracyclin, OTC; tylosin, TS; valnemulin, VLM) in swine wastewater has been developed. After filtration, aliquots (100 microl) of wastewater samples were directly injected to a column-switching LC system. Some matrix interference was removed by washing up SPE column with 0.2% formic acid solution and acetonitrile. Antibiotics eluted from SPE column were separated on analytical column by converting switching valve and were detected by MS/MS. Calibration curves using the method of standard addition had very good correlation coefficients (r > 0.99) in the range of 0.1 to 2 ng/ml. The intra-day precision of the method was less than 12% and the inter-day precision was between 6 to 17%. The detection limits were 0.01-0.1 ng/ml. When this method was applied to wastewater samples in swine facilities, four compounds (LCM, OTC, TS, and VLM) were detected.

Reverse phase HPLC method for detection and quantification of lupin seed γ-conglutin.

PubMed

Mane, Sharmilee; Bringans, Scott; Johnson, Stuart; Pareek, Vishnu; Utikar, Ranjeet

2017-09-15

A simple, selective and accurate reverse phase HPLC method was developed for detection and quantitation of γ-conglutin from lupin seed extract. A linear gradient of water and acetonitrile containing trifluoroacetic acid (TFA) on a reverse phase column (Agilent Zorbax 300SB C-18), with a flow rate of 0.8ml/min was able to produce a sharp and symmetric peak of γ-conglutin with a retention time at 29.16min. The identity of γ-conglutin in the peak was confirmed by mass spectrometry (MS/MS identification) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The data obtained from MS/MS analysis was matched against the specified database to obtain the exact match for the protein of interest. The proposed method was validated in terms of specificity, linearity, sensitivity, precision, recovery and accuracy. The analytical parameters revealed that the validated method was capable of selectively performing a good chromatographic separation of γ-conglutin from the lupin seed extract with no interference of the matrix. The detection and quantitation limit of γ-conglutin were found to be 2.68μg/ml and 8.12μg/ml respectively. The accuracy (precision and recovery) analysis of the method was conducted under repeatable conditions on different days. Intra-day and inter-day precision values less than 0.5% and recovery greater than 97% indicated high precision and accuracy of the method for analysis of γ-conglutin. The method validation findings were reproducible and can be successfully applied for routine analysis of γ-conglutin from lupin seed extract. Copyright © 2017 Elsevier B.V. All rights reserved.

[Determination of heavy metals for RoHS compliance by ICP-OES spectrometry coupled with microwave extraction system].

PubMed

Hua, Li; Wu, Yi-Ping; An, Bing; Lai, Xiao-Wei

2008-11-01

The harm of heavy metals contained in electronic and electrical equipment (EEE) on environment is of high concern by human. Aiming to handle the great challenge of RoHS compliance, the determinations of trace or ultratrace chromium (Cr), cadmium (Cd), mercury (Hg) and lead (Pb) by inductively coupled plasma optical emission spectrometry (ICP-OES) was performed in the present paper, wherein, microwave extraction technology was used to prepare the sample solutions. In addition, the precision, recovery, repeatability and interference issues of this method were also discussed. The results exhibited that using the microwave extraction system to prepare samples is more quick, lossless, contamination-free in comparison with the conventional extraction methods such as dry ashing, wet-oven extraction etc. By analyzing the recoveries of these four heavy metals over different working time and wavelengths, the good recovery range between 85% and 115% showed that there was only tiny loss or contamination during the process of microwave extraction, sample introduction and ICP detection. Repeatability experiments proved that ICP plasma had a good stability during the working time and the matrix effect was small. Interference was a problem troublesome for atomic absorption spectrometry (AAS), however, the techniques of standard additions or inter-element correction (IEC) method can effectively eliminated the interferences of Ni, As, Fe etc. with the Cd determination. By employing the multi-wavelengths and two correction point methods, the issues of background curve sloping shift and spectra overlap were successfully overcome. Besides, for the determinations of trace heavy metal elements, the relative standard deviation (RSD) was less than 3% and the detection limits were less than 1 microg x L(-10 (3sigma, n = 5) for samples, standard solutions, and standard additions, which proved that ICP-OES has a good precision and high reliability. This provided a reliable technique support for electronic and electrical (EE) industries to comply with RoHS directive.

Determination of metoprolol enantiomers in human plasma and saliva samples utilizing microextraction by packed sorbent and liquid chromatography-tandem mass spectrometry.

PubMed

Elmongy, Hatem; Ahmed, Hytham; Wahbi, Abdel-Aziz; Amini, Ahmad; Colmsjö, Anders; Abdel-Rehim, Mohamed

2016-08-01

A sensitive, accurate and reliable bioanalytical method for the enantioselective determination of metoprolol in plasma and saliva samples utilizing liquid chromatography-electrospray ionization tandem mass spectrometry was developed and validated. Human plasma and saliva samples were pretreated by microextraction by packed sorbent (MEPS) prior to analysis. A new MEPS syringe form with two inputs was used. Metoprolol enantiomers and internal standard pentycaine (IS) were eluted from MEPS sorbent using isopropanol after removal of matrix interferences using aliquots of 5% methanol in water. Complete separation of metoprolol enantiomers was achieved on a Cellulose-SB column (150 × 4.6 mm, 5 μm) using isocratic elution with mobile phase 0.1% ammonium hydroxide in hexane-isopropanol (80:20, v/v) with a flow rate of 0.8 mL/min. A post-column solvent-assisted ionization was applied to enhance metoprolol ionization signal in positive mode monitoring (+ES) using 0.5% formic acid in isopropanol at a flow rate of 0.2 mL/min. The total chromatographic run time was 10 min for each injection. The detection of metoprolol in plasma and saliva samples was performed using triple quadrupole tandem mass spectrometer in +ES under the following mass transitions: m/z 268.08 → 72.09 for metoprolol and m/z 303.3 → 154.3 for IS. The linearity range was 2.5-500 ng/mL for both R- and S-metoprolol in plasma and saliva. The limits of detection and quantitation for both enantiomers were 0.5 and 2.5 ng/mL respectively, in both matrices (plasma and saliva). The intra- and inter-day precisions were presented in terms of RSD values for replicate analysis of quality control samples and were <5%; the accuracy of determinations varied from 96 to 99%. The method was able to determine the therapeutic levels of metoprolol enantiomers in both human plasma and saliva samples successfully, which can aid in therapeutic drug monitoring in clinical laboratories. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Simultaneous determination of Eleutheroside B and Eleutheroside E in rat plasma by high performance liquid chromatography-electrospray ionization mass spectrometry and its application in a pharmacokinetic study.

PubMed

Ma, Bo; Zhang, Qi; Liu, Yinhui; Li, Jing; Xu, Qiuyu; Li, Xiaotian; Yang, Xiaojing; Yao, Di; Sun, Jingjing; Cui, Guangbo; Ying, Hanjie

2013-02-15

Eleutheroside B and Eleutheroside E, two kinds of the major bioactive saponins of Eleutherococcus senticosus, play a pivotal role in biologic activity. In this study, a specific and sensitive high performance liquid chromatography-electrospray ionization-tandem mass spectrometry method (HPLC-MS/MS) was developed and validated for simultaneous determination of Eleutheroside B and Eleutheroside E in rat plasma. The analytes were extracted from rat plasma via a simple protein precipitation procedure with methanol and polygonin was used as internal standard. Chromatographic separation was achieved on a C18 column using a gradient elution program with acetonitrile and water containing 0.1% ammonium hydroxide solution as the mobile phase, with a flow rate of 0.2mL/min. The detection was performed on a triple-quadrupole tandem mass spectrometer by multiple reactions monitoring (MRM) mode in a negative ion mode via electrospray ionization (ESI). The transition monitored were m/z 371 [M-H](-)→209 for Eleutheroside B, m/z 741[M-H](-)→579 for Eleutheroside E and m/z 389[M-H](-)→277 for internal standard. Linear calibration curves were obtained in the concentration range of 1-2000ng/mL for both (Eleutheroside B and Eleutheroside E), with a lower limit of quantification of 1ng/mL. Extraction recovery was over 80% in plasma. The intra- and inter-day precision (RSD) values were below 12% and accuracy (RE) was -2.80 to 5.70% at three QC levels for both. The assay was successfully applied to study pharmacokinetics behavior in rats after oral and intravenous administration of the single substances (Eleutheroside B and Eleutheroside E). And further research was performed by comparing the difference in pharmacokinetic behavior between the single substances and an aqueous extract of E. senticosus after oral administration. Significant difference in pharmacokinetic characteristics between the single substances and an aqueous extract was found in rat, which would be beneficial for the pre-clinical research and clinical use of E. senticosus. Copyright © 2013. Published by Elsevier B.V.

Applicability of the direct injection liquid chromatographic tandem mass spectrometric analytical approach to the sub-ngL-1 determination of perfluoro-alkyl acids in waste, surface, ground and drinking water samples.

PubMed

Ciofi, Lorenzo; Renai, Lapo; Rossini, Daniele; Ancillotti, Claudia; Falai, Alida; Fibbi, Donatella; Bruzzoniti, Maria Concetta; Santana-Rodriguez, José Juan; Orlandini, Serena; Del Bubba, Massimo

2018-01-01

The applicability of a direct injection UHPLC-MS/MS method for the analysis of several perfluoroalkyl acids (PFAAs) in a wide range of water matrices was investigated. The method is based on the direct injection of 100µL of centrifuged water sample, without any other sample treatment. Very good method detection limits (0.014-0.44ngL -1 ) and excellent intra and inter-day precision (RSD% values in the range 1.8-4.4% and 2.7-5.7%, respectively) were achieved, with a total analysis time of 20min per sample. A high number of samples - i.e. 8 drinking waters (DW), 12 ground waters (GW), 13 surface waters (SW), 8 influents and 11 effluents of wastewater treatment plants (WWTP IN and WWTP OUT ) were processed and the extent of matrix effect (ME) was calculated, highlighting the strong prevalence of |ME| < 20%. The occurrence of |ME| > 50% was occasionally observed only for perfluorooctanesulphonic and perfluorodecanoic acids. Linear discriminant analysis highlighted the great contribution of the sample origin (i.e. DW, GW, SW, WWTP IN and WWTP OUT ) to the ME. Partial least square regression (PLS) and leave-one-out cross-validation were performed in order to interpret and predict the signal suppression or enhancement phenomena as a function of physicochemical parameters of water samples (i.e. conductivity, hardness and chemical oxygen demand) and background chromatographic area. The PLS approach resulted only in an approximate screening, due to the low prediction power of the PLS models. However, for most analytes in most samples, the fitted and cross-validated values were such as to correctly distinguish between | ME | higher than 20% or below this limit. PFAAs in the aforementioned water samples were quantified by means of the standard addition method, highlighting their occurrence mainly in WWTP influents and effluents, at concentrations as high as one hundred of µgL -1 . Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination of erlotinib and tamoxifen in rat plasma using UPLC-MS/MS: Application to pharmacokinetic interaction studies.

PubMed

Maher, Hadir M; Alzoman, Nourah Z; Shehata, Shereen M

2016-08-15

Tamoxifen (TAM) is a non-steroidal estrogen receptor antagonist that enhances erlotinib (ERL)-induced cytotoxicity in the treatment of NSCLC. ERL and TAM are metabolized by CYP3A4 enzymes. In addition, both drugs have the potential of altering the enzymatic activity through either inhibition (ERL) or induction (TAM). Thus it was expected that pharmacokinetics (PK) drug-drug interactions (DDIs) could be encountered following their co-administration. In this respect, a bioanalytical UPLC-MS/MS method has been developed and validated for the simultaneous determination of ERL and TAM in rat plasma samples, using ondansetron (OND) as an internal standard (IS). Plasma samples were prepared using mixed mode cationic solid phase extraction (SPE) STRATA™ -X-C 33μm cartridges with good extraction recovery of both drugs from rat plasma (Er% from -13.92 to -3.32). The drugs were separated on a Waters BEH™ C18 column with an isocratic elution using a mobile phase composed of a mixture of acetonitrile and water, each with 0.15% formic acid, in the ratio of 80: 20, v/v. Quantitation was carried out using the positive ionization mode with multiple reaction monitoring (MRM) at m/z 394.20>278.04 (ERL), m/z 372.25>72.01 (TAM), and m/z 294.18>170.16 (OND). The method was fully validated as per the FDA guidelines over the concentration range of 0.2-50ng/mL with very low lower limit of quantification (LLOQ) of 0.2ng/mL for both ERL and TAM. The intra- and inter-day assay precision (in terms of relative standard deviation, RSD) and accuracy (in terms of percentage relative error, % Er) were evaluated for both drugs and the calculated values evaluated at four different concentration levels were within the acceptable limits (<15%) for concentrations other than LLOQ and 20% for LLOQ. The method was successfully applied to the study of possible PK-DDI following the oral administration of ERL and TAM in a combination, compared to their single administration. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimization of Microwave-Assisted Extraction Conditions for Five Major Bioactive Compounds from Flos Sophorae Immaturus (Cultivars of Sophora japonica L.) Using Response Surface Methodology.

PubMed

Liu, Jin-Liang; Li, Long-Yun; He, Guang-Hua

2016-03-02

Microwave-assisted extraction was applied to extract rutin; quercetin; genistein; kaempferol; and isorhamnetin from Flos Sophorae Immaturus. Six independent variables; namely; solvent type; particle size; extraction frequency; liquid-to-solid ratio; microwave power; and extraction time were examined. Response surface methodology using a central composite design was employed to optimize experimental conditions (liquid-to-solid ratio; microwave power; and extraction time) based on the results of single factor tests to extract the five major components in Flos Sophorae Immaturus. Experimental data were fitted to a second-order polynomial equation using multiple regression analysis. Data were also analyzed using appropriate statistical methods. Optimal extraction conditions were as follows: extraction solvent; 100% methanol; particle size; 100 mesh; extraction frequency; 1; liquid-to-solid ratio; 50:1; microwave power; 287 W; and extraction time; 80 s. A rapid and sensitive ultra-high performance liquid chromatography method coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (EIS-Q-TOF MS/MS) was developed and validated for the simultaneous determination of rutin; quercetin; genistein; kaempferol; and isorhamnetin in Flos Sophorae Immaturus. Chromatographic separation was accomplished on a Kinetex C18 column (100 mm × 2.1 mm; 2.6 μm) at 40 °C within 5 min. The mobile phase consisted of 0.1% aqueous formic acid and acetonitrile (71:29; v/v). Isocratic elution was carried out at a flow rate of 0.35 mL/min. The constituents of Flos Sophorae Immaturus were simultaneously identified by EIS-Q-TOF MS/MS in multiple reaction monitoring mode. During quantitative analysis; all of the calibration curves showed good linear relationships (R² > 0.999) within the tested ranges; and mean recoveries ranged from 96.0216% to 101.0601%. The precision determined through intra- and inter-day studies showed an RSD% of <2.833%. These results demonstrate that the developed method is accurate and effective and could be readily utilized for the comprehensive quality control of Flos Sophorae Immaturus.

Simultaneous analysis method for GHB, ketamine, norketamine, phenobarbital, thiopental, zolpidem, zopiclone and phenytoin in urine, using C18 poroshell column.

PubMed

Anilanmert, Beril; Çavuş, Fatma; Narin, Ibrahim; Cengiz, Salih; Sertler, Şefika; Özdemir, Ali Acar; Açikkol, Münevver

2016-06-01

Date-rape drugs have the potential to be used in drug-facilitated sexual assault, organ theft and property theft. Since they are colorless, tasteless and odorless, victims can drink without noticing, when added to the beverages. These drugs must be detected in time, before they are cleared up from the biofluids. A simultaneous extraction and determination method in urine for GHB, ketamine, norketamine, phenobarbital, thiopental, zolpidem, zopiclone and phenytoin (an anticonvulsant and antiepileptic drug) with LC-MS/MS was developed for the first time with analytically acceptable recoveries and validated. A 4 steps liquid-liquid extraction was applied, using only 1.000mL urine. A new age commercial C18 poroshell column with high column efficiency was used for LC-MS/MS analysis with a fast isocratic elution as 5.5min. A new MS transition were introduced for barbital. 222.7>179.8 with the effect of acetonitrile. Recoveries (%) were between 80.98-99.27 for all analytes, except for GHB which was 71.46. LOD and LOQ values were found in the ranges of 0.59-49.50 and 9.20-80.80ngmL(-1) for all the analytes (except for GHB:3.44 and 6.00μgmL(-1)). HorRat values calculated (between 0.25-1.21), revealed that the inter-day and interanalist precisions (RSD%≤14.54%) acceptable. The simultaneous extraction and determination of these 8 analytes in urine is challenging because of the difficulty arising from the different chemical properties of some. Since the procedure can extract drugs from a wide range of polarity and pKa, it increases the window of detection. Group representatives from barbiturates, z-drugs, ketamine, phenytoin and polar acidic drugs (GHB) have been successfully analyzed in this study with low detection limits. The method is important from the point of determining the combined or single use of these drugs in crimes and finding out the reasons of deaths related to these drugs. Copyright © 2016 Elsevier B.V. All rights reserved.

New approach for assessing human perfluoroalkyl exposure via hair.

PubMed

Alves, Andreia; Jacobs, Griet; Vanermen, Guido; Covaci, Adrian; Voorspoels, Stefan

2015-11-01

In the recent years hair has been increasingly used as alternative matrix in human biomonitoring (HBM) of environmental pollutants. Sampling advantages and time integration of exposure assessment seems the most attractive features of hair matrix. In the current study, a novel miniaturized method was developed and validated for measuring 15 perfluoroalkyl substances (PFAS), including perfluoro n-butanoic acid (PFBA), perfluoro n-pentanoic acid (PFPeA), perfluoro n-hexanoic acid (PFHxA), perfluoro n-heptanoic acid (PFHpA), perfluor n-octanoic acid (PFOA), perfluoro n-nonanoic acid (PFNA), perfluoro tetradecanoic acid (PFTeDA), perfluorobutane sulfonic acid (PFBS), perfluoro pentane sulfonic acid (PFPeS), perfluorohexane sulfonic acid (PFHxS), perfluoroheptane sulfonic acid (PFHpS), perfluorooctane sulfonic acid (PFOS), perfluorononane sulfonic acid (PFNS), perfluorodecane sulfonic acid (PFDS) and perfluorododecane sulfonic acid (PFDoS) in human hair by liquid chromatography tandem mass spectrometry (LC-MS/MS). After extraction using ethyl acetate, dispersive ENVI-Carb was used for clean-up. Good intra- and inter-day precision for low (LQ 5 ng/g hair) and high spike (HQ 15n g/g) levels were achieved (in general RSD <10%). The accuracy was assessed using recoveries (%), which ranged between 68-118% (LQ) and 70-121% (HQ). The instrumental limit of detection (LODi) and limit of quantification (LOQi) were between 1-4 pg/g hair and 3-13 pg/g hair, respectively. The method limit of quantification (LOQm) ranged between 6 and 301 pg/g hair. The PFAS levels were measured in 30 human hair samples indicating that the levels are low (14-1534 pg/g hair). Some PFAS were not present in any hair sample (e.g. PFHpA, PFTeDA, PFNA, PFPeS, PFHpS, PFOS and PFNS), while other PFAS were frequently detected (PFBA, PFPeA, PFHxA, PFOA, PFBS, PFHxS, PFOS, PFDS and PFDoS) in human hair. Although levels in general were low, there is evidence of higher human exposure to some analytes, such as PFBA, PFPeA, PFHxA, PFOA, PFBS, PFHxS, and PFDoS. The current study shows that hair is a suitable alternative non-invasive matrix for exposure assessment of PFAS. Copyright © 2015 Elsevier B.V. All rights reserved.

Neuropeptide Y as an indicator of successful alterations in sympathetic nervous activity after renal sympathetic denervation.

PubMed

Dörr, Oliver; Ewen, Sebastian; Liebetrau, Christoph; Möllmann, Helge; Gaede, Luise; Linz, Dominik; Hohl, Mathias; Troidl, Christian; Bauer, Timm; Böhm, Michael; Hamm, Christian; Mahfoud, Felix; Nef, Holger

2015-12-01

Renal sympathetic denervation (RSD) represents a safe and effective treatment option for certain patients with resistant hypertension and has been shown to decrease sympathetic activity. Neuropeptide Y (NPY) is a neurotransmitter that is co-released with norepinephrine and is up-regulated during increased sympathetic activity. The aim of the present study was to examine the effect of RSD on NPY and to analyze the association between changes in NPY levels and blood pressure reduction after RSD. A total of 150 consecutive patients (age 64.9 ± 10.2 years) from three clinical centers undergoing RSD were included in this study. Response to RSD was defined as an office systolic blood pressure (SBP) reduction of >10 mmHg 6 months after RSD. Venous blood samples for measurement of NPY were collected prior to and 6 months after RSD. BP and NPY levels were significantly reduced by 23/9 mmHg (p = 0.001/0.001) and 0.24 mg/dL (p < 0.01) 6 months after RSD. There was a significant correlation between baseline SBP- and RSD-related systolic BP reduction (r = -0.43; p < 0.001) and between serum NPY baseline values and NPY level changes (r = -0.52; p < 0.001) at the 6-month follow-up. The BP response to RSD (>10 mmHg) was associated with a significantly greater reduction in NPY level when compared with BP non-responders (p = 0.001). This study demonstrates an effect of RSD on serum NPY levels, a specific marker for sympathetic activity. The association between RSD-related changes in SBP and NPY levels provides further evidence of the effect of RSD on the sympathetic nervous system.

The E. coli Anti-Sigma Factor Rsd: Studies on the Specificity and Regulation of Its Expression

PubMed Central

Hofmann, Nina; Wurm, Reinhild; Wagner, Rolf

2011-01-01

Background Among the seven different sigma factors in E. coli σ70 has the highest concentration and affinity for the core RNA polymerase. The E. coli protein Rsd is regarded as an anti-sigma factor, inhibiting σ70-dependent transcription at the onset of stationary growth. Although binding of Rsd to σ70 has been shown and numerous structural studies on Rsd have been performed the detailed mechanism of action is still unknown. Methodology/Principal Findings We have performed studies to unravel the function and regulation of Rsd expression in vitro and in vivo. Cross-linking and affinity binding revealed that Rsd is able to interact with σ70, with the core enzyme of RNA polymerase and is able to form dimers in solution. Unexpectedly, we find that Rsd does also interact with σ38, the stationary phase-specific sigma factor. This interaction was further corroborated by gel retardation and footprinting studies with different promoter fragments and σ38- or σ70-containing RNA polymerase in presence of Rsd. Under competitive in vitro transcription conditions, in presence of both sigma factors, a selective inhibition of σ70-dependent transcription was prevailing, however. Analysis of rsd expression revealed that the nucleoid-associated proteins H-NS and FIS, StpA and LRP bind to the regulatory region of the rsd promoters. Furthermore, the major promoter P2 was shown to be down-regulated in vivo by RpoS, the stationary phase-specific sigma factor and the transcription factor DksA, while induction of the stringent control enhanced rsd promoter activity. Most notably, the dam-dependent methylation of a cluster of GATC sites turned out to be important for efficient rsd transcription. Conclusions/Significance The results contribute to a better understanding of the intricate mechanism of Rsd-mediated sigma factor specificity changes during stationary phase. PMID:21573101

The E. coli anti-sigma factor Rsd: studies on the specificity and regulation of its expression.

PubMed

Hofmann, Nina; Wurm, Reinhild; Wagner, Rolf

2011-05-06

Among the seven different sigma factors in E. coli σ(70) has the highest concentration and affinity for the core RNA polymerase. The E. coli protein Rsd is regarded as an anti-sigma factor, inhibiting σ(70)-dependent transcription at the onset of stationary growth. Although binding of Rsd to σ(70) has been shown and numerous structural studies on Rsd have been performed the detailed mechanism of action is still unknown. We have performed studies to unravel the function and regulation of Rsd expression in vitro and in vivo. Cross-linking and affinity binding revealed that Rsd is able to interact with σ(70), with the core enzyme of RNA polymerase and is able to form dimers in solution. Unexpectedly, we find that Rsd does also interact with σ(38), the stationary phase-specific sigma factor. This interaction was further corroborated by gel retardation and footprinting studies with different promoter fragments and σ(38)- or σ(70)-containing RNA polymerase in presence of Rsd. Under competitive in vitro transcription conditions, in presence of both sigma factors, a selective inhibition of σ(70)-dependent transcription was prevailing, however. Analysis of rsd expression revealed that the nucleoid-associated proteins H-NS and FIS, StpA and LRP bind to the regulatory region of the rsd promoters. Furthermore, the major promoter P2 was shown to be down-regulated in vivo by RpoS, the stationary phase-specific sigma factor and the transcription factor DksA, while induction of the stringent control enhanced rsd promoter activity. Most notably, the dam-dependent methylation of a cluster of GATC sites turned out to be important for efficient rsd transcription. The results contribute to a better understanding of the intricate mechanism of Rsd-mediated sigma factor specificity changes during stationary phase.

Precise montaging and metric quantification of retinal surface area from ultra-widefield fundus photography and fluorescein angiography.

PubMed

Croft, Daniel E; van Hemert, Jano; Wykoff, Charles C; Clifton, David; Verhoek, Michael; Fleming, Alan; Brown, David M

2014-01-01

Accurate quantification of retinal surface area from ultra-widefield (UWF) images is challenging due to warping produced when the retina is projected onto a two-dimensional plane for analysis. By accounting for this, the authors sought to precisely montage and accurately quantify retinal surface area in square millimeters. Montages were created using Optos 200Tx (Optos, Dunfermline, U.K.) images taken at different gaze angles. A transformation projected the images to their correct location on a three-dimensional model. Area was quantified with spherical trigonometry. Warping, precision, and accuracy were assessed. Uncorrected, posterior pixels represented up to 79% greater surface area than peripheral pixels. Assessing precision, a standard region was quantified across 10 montages of the same eye (RSD: 0.7%; mean: 408.97 mm(2); range: 405.34-413.87 mm(2)). Assessing accuracy, 50 patients' disc areas were quantified (mean: 2.21 mm(2); SE: 0.06 mm(2)), and the results fell within the normative range. By accounting for warping inherent in UWF images, precise montaging and accurate quantification of retinal surface area in square millimeters were achieved. Copyright 2014, SLACK Incorporated.

Mapping of the Rsd Contact Site on the Sigma 70 Subunit of Escherichia coli RNA Polymerase

PubMed Central

Jishage, Miki; Dasgupta, Dipak; Ishihama, Akira

2001-01-01

Rsd (regulator of sigma D) is an anti-sigma factor for the Escherichia coli RNA polymerase ς70 subunit. The contact site of Rsd on ς70 was analyzed after mapping of the contact-dependent cleavage sites by Rsd-tethered iron-p-bromoacetamidobenzyl EDTA and by analysis of the complex formation between Ala-substituted ς70 and Rsd. Results indicate that the Rsd contact site is located downstream of the promoter −35 recognition helix-turn-helix motif within region 4, overlapping with the regions involved in interaction with both core enzyme and ς70 contact transcription factors. PMID:11292818

Mapping of the Rsd contact site on the sigma 70 subunit of Escherichia coli RNA polymerase.

PubMed

Jishage, M; Dasgupta, D; Ishihama, A

2001-05-01

Rsd (regulator of sigma D) is an anti-sigma factor for the Escherichia coli RNA polymerase sigma(70) subunit. The contact site of Rsd on sigma(70) was analyzed after mapping of the contact-dependent cleavage sites by Rsd-tethered iron-p-bromoacetamidobenzyl EDTA and by analysis of the complex formation between Ala-substituted sigma(70) and Rsd. Results indicate that the Rsd contact site is located downstream of the promoter -35 recognition helix-turn-helix motif within region 4, overlapping with the regions involved in interaction with both core enzyme and sigma(70) contact transcription factors.

Analysis of Mycosporine-Like Amino Acids in Selected Algae and Cyanobacteria by Hydrophilic Interaction Liquid Chromatography and a Novel MAA from the Red Alga Catenella repens

PubMed Central

Hartmann, Anja; Becker, Kathrin; Karsten, Ulf; Remias, Daniel; Ganzera, Markus

2015-01-01

Mycosporine-like amino acids (MAAs), a group of small secondary metabolites found in algae, cyanobacteria, lichens and fungi, have become ecologically and pharmacologically relevant because of their pronounced UV-absorbing and photo-protective potential. Their analytical characterization is generally achieved by reversed phase HPLC and the compounds are often quantified based on molar extinction coefficients. As an alternative approach, in our study a fully validated hydrophilic interaction liquid chromatography (HILIC) method is presented. It enables the precise quantification of several analytes with adequate retention times in a single run, and can be coupled directly to MS. Excellent linear correlation coefficients (R2 > 0.9991) were obtained, with limit of detection (LOD) values ranging from 0.16 to 0.43 µg/mL. Furthermore, the assay was found to be accurate (recovery rates from 89.8% to 104.1%) and precise (intra-day precision: 5.6%, inter-day precision ≤6.6%). Several algae were assayed for their content of known MAAs like porphyra-334, shinorine, and palythine. Liquid chromatography-mass spectrometry (LC-MS) data indicated a novel compound in some of them, which could be isolated from the marine species Catenella repens and structurally elucidated by nuclear magnetic resonance spectroscopy (NMR) as (E)-3-hydroxy-2-((5-hydroxy-5-(hydroxymethyl)-2-methoxy-3-((2-sulfoethyl)amino)cyclohex-2-en-1-ylidene)amino) propanoic acid, a novel MAA called catenelline. PMID:26473886

Analysis of Mycosporine-Like Amino Acids in Selected Algae and Cyanobacteria by Hydrophilic Interaction Liquid Chromatography and a Novel MAA from the Red Alga Catenella repens.

PubMed

Hartmann, Anja; Becker, Kathrin; Karsten, Ulf; Remias, Daniel; Ganzera, Markus

2015-10-09

Mycosporine-like amino acids (MAAs), a group of small secondary metabolites found in algae, cyanobacteria, lichens and fungi, have become ecologically and pharmacologically relevant because of their pronounced UV-absorbing and photo-protective potential. Their analytical characterization is generally achieved by reversed phase HPLC and the compounds are often quantified based on molar extinction coefficients. As an alternative approach, in our study a fully validated hydrophilic interaction liquid chromatography (HILIC) method is presented. It enables the precise quantification of several analytes with adequate retention times in a single run, and can be coupled directly to MS. Excellent linear correlation coefficients (R² > 0.9991) were obtained, with limit of detection (LOD) values ranging from 0.16 to 0.43 µg/mL. Furthermore, the assay was found to be accurate (recovery rates from 89.8% to 104.1%) and precise (intra-day precision: 5.6%, inter-day precision ≤6.6%). Several algae were assayed for their content of known MAAs like porphyra-334, shinorine, and palythine. Liquid chromatography-mass spectrometry (LC-MS) data indicated a novel compound in some of them, which could be isolated from the marine species Catenella repens and structurally elucidated by nuclear magnetic resonance spectroscopy (NMR) as (E)-3-hydroxy-2-((5-hydroxy-5-(hydroxymethyl)-2-methoxy-3-((2-sulfoethyl)amino)cyclohex-2-en-1-ylidene)amino) propanoic acid, a novel MAA called catenelline.

Studies of the Escherichia coli Rsd-sigma70 complex.

PubMed

Westblade, Lars F; Ilag, Leopold L; Powell, Andrew K; Kolb, Annie; Robinson, Carol V; Busby, Stephen J W

2004-01-16

Escherichia coli Rsd protein was previously identified on the basis of its binding to the RNA polymerase sigma(70) subunit. The Rsd-sigma(70) complex has been studied using different methods. Our data show that Rsd associates with sigma(70) to form a complex with a stoichiometry of 1:1. Alanine scanning and deletion mutagenesis were used to locate regions of sigma(70) that are required for the formation of the Rsd-sigma(70) complex.

The C2H2 Transcription Factor REGULATOR OF SYMBIOSOME DIFFERENTIATION Represses Transcription of the Secretory Pathway Gene VAMP721a and Promotes Symbiosome Development in Medicago truncatula[W][OPEN

PubMed Central

Sinharoy, Senjuti; Torres-Jerez, Ivone; Bandyopadhyay, Kaustav; Kereszt, Attila; Pislariu, Catalina I.; Nakashima, Jin; Benedito, Vagner A.; Kondorosi, Eva; Udvardi, Michael K.

2013-01-01

Transcription factors (TFs) are thought to regulate many aspects of nodule and symbiosis development in legumes, although few TFs have been characterized functionally. Here, we describe REGULATOR OF SYMBIOSOME DIFFERENTIATION (RSD) of Medicago truncatula, a member of the Cysteine-2/Histidine-2 (C2H2) family of plant TFs that is required for normal symbiosome differentiation during nodule development. RSD is expressed in a nodule-specific manner, with maximal transcript levels in the bacterial invasion zone. A tobacco (Nicotiana tabacum) retrotransposon (Tnt1) insertion rsd mutant produced nodules that were unable to fix nitrogen and that contained incompletely differentiated symbiosomes and bacteroids. RSD protein was localized to the nucleus, consistent with a role of the protein in transcriptional regulation. RSD acted as a transcriptional repressor in a heterologous yeast assay. Transcriptome analysis of an rsd mutant identified 11 genes as potential targets of RSD repression. RSD interacted physically with the promoter of one of these genes, VAMP721a, which encodes vesicle-associated membrane protein 721a. Thus, RSD may influence symbiosome development in part by repressing transcription of VAMP721a and modifying vesicle trafficking in nodule cells. This establishes RSD as a TF implicated directly in symbiosome and bacteroid differentiation and a transcriptional regulator of secretory pathway genes in plants. PMID:24082011

The C2H2 transcription factor regulator of symbiosome differentiation represses transcription of the secretory pathway gene VAMP721a and promotes symbiosome development in Medicago truncatula.

PubMed

Sinharoy, Senjuti; Torres-Jerez, Ivone; Bandyopadhyay, Kaustav; Kereszt, Attila; Pislariu, Catalina I; Nakashima, Jin; Benedito, Vagner A; Kondorosi, Eva; Udvardi, Michael K

2013-09-01

Transcription factors (TFs) are thought to regulate many aspects of nodule and symbiosis development in legumes, although few TFs have been characterized functionally. Here, we describe regulator of symbiosome differentiation (RSD) of Medicago truncatula, a member of the Cysteine-2/Histidine-2 (C2H2) family of plant TFs that is required for normal symbiosome differentiation during nodule development. RSD is expressed in a nodule-specific manner, with maximal transcript levels in the bacterial invasion zone. A tobacco (Nicotiana tabacum) retrotransposon (Tnt1) insertion rsd mutant produced nodules that were unable to fix nitrogen and that contained incompletely differentiated symbiosomes and bacteroids. RSD protein was localized to the nucleus, consistent with a role of the protein in transcriptional regulation. RSD acted as a transcriptional repressor in a heterologous yeast assay. Transcriptome analysis of an rsd mutant identified 11 genes as potential targets of RSD repression. RSD interacted physically with the promoter of one of these genes, VAMP721a, which encodes vesicle-associated membrane protein 721a. Thus, RSD may influence symbiosome development in part by repressing transcription of VAMP721a and modifying vesicle trafficking in nodule cells. This establishes RSD as a TF implicated directly in symbiosome and bacteroid differentiation and a transcriptional regulator of secretory pathway genes in plants.

The Escherichia coli Regulator of Sigma 70 Protein, Rsd, Can Up-Regulate Some Stress-Dependent Promoters by Sequestering Sigma 70▿

PubMed Central

Mitchell, Jennie E.; Oshima, Taku; Piper, Sarah E.; Webster, Christine L.; Westblade, Lars F.; Karimova, Gouzel; Ladant, Daniel; Kolb, Annie; Hobman, Jon L.; Busby, Stephen J. W.; Lee, David J.

2007-01-01

The Escherichia coli Rsd protein forms complexes with the RNA polymerase σ70 factor, but its biological role is not understood. Transcriptome analysis shows that overexpression of Rsd causes increased expression from some promoters whose expression depends on the alternative σ38 factor, and this was confirmed by experiments with lac fusions at selected promoters. The LP18 substitution in Rsd increases the Rsd-dependent stimulation of these promoter-lac fusions. Analysis with a bacterial two-hybrid system shows that the LP18 substitution in Rsd increases its interaction with σ70. Our experiments support a model in which the role of Rsd is primarily to sequester σ70, thereby increasing the levels of RNA polymerase containing the alternative σ38 factor. PMID:17351046

Precise orbit determination of Multi-GNSS constellation including GPS GLONASS BDS and GALIEO

NASA Astrophysics Data System (ADS)

Dai, Xiaolei

2014-05-01

In addition to the existing American global positioning system (GPS) and the Russian global navigation satellite system (GLONASS), the new generation of GNSS is emerging and developing, such as the Chinese BeiDou satellite navigation system (BDS) and the European GALILEO system. Multi-constellation is expected to contribute to more accurate and reliable positioning and navigation service. However, the application of multi-constellation challenges the traditional precise orbit determination (POD) strategy that was designed usually for single constellation. In this contribution, we exploit a more rigorous multi-constellation POD strategy for the ongoing IGS multi-GNSS experiment (MGEX) where the common parameters are identical for each system, and the frequency- and system-specified parameters are employed to account for the inter-frequency and inter-system biases. Since the authorized BDS attitude model is not yet released, different BDS attitude model are implemented and their impact on orbit accuracy are studied. The proposed POD strategy was implemented in the PANDA (Position and Navigation Data Analyst) software and can process observations from GPS, GLONASS, BDS and GALILEO together. The strategy is evaluated with the multi-constellation observations from about 90 MGEX stations and BDS observations from the BeiDou experimental tracking network (BETN) of Wuhan University (WHU). Of all the MGEX stations, 28 stations record BDS observation, and about 80 stations record GALILEO observations. All these data were processed together in our software, resulting in the multi-constellation POD solutions. We assessed the orbit accuracy for GPS and GLONASS by comparing our solutions with the IGS final orbit, and for BDS and GALILEO by overlapping our daily orbit solution. The stability of inter-frequency bias of GLONASS and inter-system biases w.r.t. GPS for GLONASS, BDS and GALILEO were investigated. At last, we carried out precise point positioning (PPP) using the multi-constellation POD orbit and clock products, and analyzed the contribution of these POD products to PPP. Keywords: Multi-GNSS, Precise Orbit Determination, Inter-frequency bias, Inter-system bias, Precise Point Positioning

Comparison of Digestion Methods for the Determination of Trace Elements and Heavy Metals in Human Hair and Nails

PubMed Central

Ishak, Ismarulyusda; Rosli, Farah Dayana; Mohamed, Jamaludin; Mohd Ismail, Muhammad Faiz

2015-01-01

Background Microwave is the most reliable sample digestion method. However, it requires expensive microwave digester automation and has relatively low productivity. In this study, three non-automated digestion methods, i.e. wet acid digestion using nitric acid (HNO3) and hydrogen peroxide (H2O2), wet acid digestion using HNO3, and dry washing, are compared in order to determine the best approach. Methods Certified reference material IAEA-086 (International Atomic Energy Agency, Austria) and hair and nail samples from 20 female students of Universiti Kebangsaan Malaysia, aged 19 to 30 years, were collected and analysed using the three digestion methods. Results For hair samples, analysis of variance of repeated measures showed significant differences in the level of all elements (P < 0.001) between the three methods. For nail samples, only the copper (Cu) level showed no significant difference (P = 0.100) between methods. Wet acid digestion using HNO3 and H2O2 showed the best within- and between-run relative standard deviation (RSD) values, with within-run RSD for all elements, except for selenium (Se), < 5%. The between-run precision ranges from 6.14% to 17.96% for hair and from 3.53% to 11.52% for nail samples. Wet acid digestion using HNO3 and H2O2 showed both good accuracy and precision for manganese (Mn) and magnesium (Mg), with percentage recoveries of 110% and 96.9%, respectively. All elements show higher method detection limit (MDL) values than the previous study: 0.05 μg/g Mg for wet acid digestion using HNO3, 0.02 μg/g Se for wet acid digestion using HNO3 and H2O2, and 0.2 μg/g Mg for dry ash method. Conclusion Wet acid digestion using HNO3 and H2O2 proved to be the best method in terms of precision, accuracy, recovery, and MDL. However, only Mn and Mg showed adequate precision, accuracy, and percentage of recovery. PMID:28223880

The Relation Between Reflex Sympathetic Dystrophy Syndrome and Trauma Severity in Patients With Distal Tibia Fracture

PubMed Central

Bahador, Reza; Mirbolook, Ahmadreza; Arbab, Sara; Derakhshan, Pooya; Gholizadeh, Amirmohammad; Abedi, Sadegh

2016-01-01

Background Reflex sympathetic dystrophy (RSD) syndrome is a multifactorial disorder with clinical features of neurogenic inflammation that causes hypersensitivity to pain or severe allodynia as well as blood flow problems, swelling, skin discoloration and maladaptive neuroplasticity due to vasomotor disorders. Patients with major trauma are prone to homeostasis leading to inflammatory response syndrome and multiple organ distress syndrome. Several studies have investigated the etiology of this condition, but the cause remains unknown. The role of associated factors such as the limb immobilization technique and genetics has been reported in the development of this complication, but, so far, there is no information regarding the effect of trauma severity on the risk of RSD occurrence. Objectives Given the importance of diagnosing and treating this condition, we aimed to study the effect of trauma severity on the prevalence of RSD. Patients and Methods In this cross-sectional study, we examined patients with distal tibial fracture who visited Rasht Poursina hospital from 2010 to 2013. Exclusion criteria included associated fractures, underlying musculoskeletal diseases and mental and cognitive problems. To assess the severity of the initial injury in patients, the Hannover Fracture Scale 98 (HFS98) scoring checklist was used. The diagnosis of RSD was made on the basis of the IASP criterion. Demographic data, HFS98 scores, and information regarding RSD prevalence were analyzed using SPSS version 20. The Mann Whitney U nonparametric test was used for variables that were not normally distributed; the chi-square test was used to compare the qualitative variables. Results Among the 488 patients, 292 (59.83%) were male. The mean age of the study population was 44 ± 9.82 years. During the 6-month follow-up, RSD occurred in 45 patients, of whom 28 (62.22%) were female and 17 (37.77%) were male; there was thus a significant difference in the prevalence of RSD in terms of gender (P = 0.00; chi square test). The mean HFS98 score in patients without and with RSD was 3.081 ± 4.083 and 4.080 ± 4.622, respectively, and the difference was not statistically significant (P = 0.363; Mann Whitney U test). Analyses of the eight items of HFS98 shows that local circulation in patients with RSD is significantly better than that in patients without RDS (0.683 ± 0.822 vs. 0.528 ± 0.629, respectively). Statistical analysis showed that the odds ratio for RSD for patients with HFS95 score > 0 was 1.079 (confidence interval [CI]: 0.898 - 1.333). Moreover, the odds ratio for RSD was 1.100 (CI: 795 - 1.531) in patients with an injury severity score higher than the calculated mean score in patients without RSD (> 4.083). Conclusions The results suggest no significant relationship between the severity of injury and risk of RSD occurrence, although the mean injury severity score was higher in patients with RSD than in those without RSD in this study population. The lower score of local circulation in patients with RSD than in those without RSD is a statistically significant finding and can be attributed to changes in the antioxidant levels at the injury site, which is one of the main mechanisms for the onset of RSD. Wound contamination was also justifiably higher in patients with RSD, although the difference was not statistically significant. In summary, the severity of injury alone cannot be a determining factor for predicting the probability of RSD. PMID:27626009

The Relation Between Reflex Sympathetic Dystrophy Syndrome and Trauma Severity in Patients With Distal Tibia Fracture.

PubMed

Bahador, Reza; Mirbolook, Ahmadreza; Arbab, Sara; Derakhshan, Pooya; Gholizadeh, Amirmohammad; Abedi, Sadegh

2016-05-01

Reflex sympathetic dystrophy (RSD) syndrome is a multifactorial disorder with clinical features of neurogenic inflammation that causes hypersensitivity to pain or severe allodynia as well as blood flow problems, swelling, skin discoloration and maladaptive neuroplasticity due to vasomotor disorders. Patients with major trauma are prone to homeostasis leading to inflammatory response syndrome and multiple organ distress syndrome. Several studies have investigated the etiology of this condition, but the cause remains unknown. The role of associated factors such as the limb immobilization technique and genetics has been reported in the development of this complication, but, so far, there is no information regarding the effect of trauma severity on the risk of RSD occurrence. Given the importance of diagnosing and treating this condition, we aimed to study the effect of trauma severity on the prevalence of RSD. In this cross-sectional study, we examined patients with distal tibial fracture who visited Rasht Poursina hospital from 2010 to 2013. Exclusion criteria included associated fractures, underlying musculoskeletal diseases and mental and cognitive problems. To assess the severity of the initial injury in patients, the Hannover Fracture Scale 98 (HFS98) scoring checklist was used. The diagnosis of RSD was made on the basis of the IASP criterion. Demographic data, HFS98 scores, and information regarding RSD prevalence were analyzed using SPSS version 20. The Mann Whitney U nonparametric test was used for variables that were not normally distributed; the chi-square test was used to compare the qualitative variables. Among the 488 patients, 292 (59.83%) were male. The mean age of the study population was 44 ± 9.82 years. During the 6-month follow-up, RSD occurred in 45 patients, of whom 28 (62.22%) were female and 17 (37.77%) were male; there was thus a significant difference in the prevalence of RSD in terms of gender (P = 0.00; chi square test). The mean HFS98 score in patients without and with RSD was 3.081 ± 4.083 and 4.080 ± 4.622, respectively, and the difference was not statistically significant (P = 0.363; Mann Whitney U test). Analyses of the eight items of HFS98 shows that local circulation in patients with RSD is significantly better than that in patients without RDS (0.683 ± 0.822 vs. 0.528 ± 0.629, respectively). Statistical analysis showed that the odds ratio for RSD for patients with HFS95 score > 0 was 1.079 (confidence interval [CI]: 0.898 - 1.333). Moreover, the odds ratio for RSD was 1.100 (CI: 795 - 1.531) in patients with an injury severity score higher than the calculated mean score in patients without RSD (> 4.083). The results suggest no significant relationship between the severity of injury and risk of RSD occurrence, although the mean injury severity score was higher in patients with RSD than in those without RSD in this study population. The lower score of local circulation in patients with RSD than in those without RSD is a statistically significant finding and can be attributed to changes in the antioxidant levels at the injury site, which is one of the main mechanisms for the onset of RSD. Wound contamination was also justifiably higher in patients with RSD, although the difference was not statistically significant. In summary, the severity of injury alone cannot be a determining factor for predicting the probability of RSD.

Rapid determination of branched chain amino acids in human blood plasma by pressure-assisted capillary electrophoresis with contactless conductivity detection.

PubMed

Tůma, Petr; Gojda, Jan

2015-08-01

A CE method with contactless conductivity detection has been developed for the clinical determination of the branched chain amino acids (BCAAs) valine, isoleucine and leucine in human blood plasma. The CE separation was performed in an optimised BGE with composition of 3.2 M acetic acid in 20% v/v methanol, pH 2.0. The achieved separation time was 125 s when using a capillary with an effective length of 14.7 cm, electric field intensity of 0.96 kV/cm and simultaneous application of a hydrodynamic pressure of 50 mbar. The separation efficiency in blood plasma equalled 461 000 theoretical plates/m for valine and isoleucine, and 455 000 theoretical plates/m for leucine; the detection limits are equal to 0.4 μM for all three amino acids. The RSD values for repeatability of the migration time equalled 0.1% for measurements during a single day and 0.3% for measurements on different days; the RSD values for repeatability of the peak areas equalled 2.3-2.6% for measurements during a single day and 2.7-4.6% for measurements on different days. It followed from the performed tests that the plasmatic levels of BCAAs attain a maximum 60 min after intravenous application of an infusion of BCAAs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination and quantification of active phenolic compounds in pigeon pea leaves and its medicinal product using liquid chromatography–tandem mass spectrometry.

PubMed

Liu, Wei; Kong, Yu; Zu, Yuangang; Fu, Yujie; Luo, Meng; Zhang, Lin; Li, Ji

2010-07-09

A novel method using liquid chromatography coupled to electrospray ionization mass spectrometry (LC-ESI-MS) has been optimized and established for the qualitative and quantitative analysis of ten active phenolic compounds originating from the pigeon pea leaves and a medicinal product thereof (Tongluo Shenggu capsules). In the present study, the chromatographic separation was achieved by means of a HiQ Sil C18V reversed-phase column with a mobile phase consisting of methanol and 0.1% formic acid aqueous solution. Low-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS) using the selected reaction monitoring (SRM) analysis was employed for the detection of ten analytes which included six flavonoids, two isoflavonoids and two stilbenes. All calibration curves showed excellent coefficients of determination (r(2) ≥ 0.9937) within the range of tested concentrations. The intra- and inter-day variations were below 5.36% in terms of relative standard deviation (RSD). The recoveries were 95.08-104.98% with RSDs of 2.06-4.26% for spiked samples of pigeon pea leaves. The method developed was a rapid, efficient and accurate LC-MS/MS method for the detection of phenolic compounds, which can be applied for quality control of pigeon pea leaves and related medicinal products.

A gas chromatography-mass spectrometry assay to quantify camphor extracted from goat serum.

PubMed

Lee, Kyung-Min; Dai, Susie Y; Herrman, Timothy J; Musser, Jeffrey M B

2012-09-15

A sensitive gas chromatography-mass spectrometry (GC-MS) method was developed and validated for quantification and pharmacokinetics of camphor, a major monoterpene of juniper plant, in goat serum. Camphor and internal standard (terpinolene) eluates from solid phase extraction (SPE) with ethyl acetate yielded well resolved peaks and were clearly identified in total and selected ion chromatograms. The elution and injection volumes were optimized for improved detection and quantification of camphor based on peak shape, signal to noise ratio, recoveries, and repeatability. The matrix calibration curve with the good linearity (R(2)=0.998) and response in the range of 0.005-10.0 μg/mL was used to determine camphor concentration in goat serum. The GC-MS method offered sufficiently low limits of detection (1 ng/mL) and quantitation (3 ng/mL) for camphor concentration in goat serum for the pharmacokinetic study. The proposed method showed good intra- and inter-day variation with relative standard deviation (RSD) of 0.2-7.7% and produced good recovery (96.0-111.6%) and reproducibility (1.6-6.1%) at all spiked levels. Using this method on serum samples obtained from two goats orally dosed with camphor confirmed that the method is suitable for camphor studies in animals. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of Tangeretin in Rat Plasma: Assessment of Its Clearance and Absolute Oral Bioavailability.

PubMed

Elhennawy, Mai Gamal; Lin, Hai-Shu

2017-12-29

Tangeretin (TAN) is a dietary polymethoxylated flavone that possesses a broad scope of pharmacological activities. A simple high-performance liquid chromatography (HPLC) method was developed and validated in this study to quantify TAN in plasma of Sprague-Dawley rats. The lower limit of quantification (LLOQ) was 15 ng/mL; the intra- and inter-day assay variations expressed in the form of relative standard deviation (RSD) were all less than 10%; and the assay accuracy was within 100 ± 15%. Subsequently, pharmacokinetic profiles of TAN were explored and established. Upon single intravenous administration (10 mg/kg), TAN had rapid clearance ( Cl = 94.1 ± 20.2 mL/min/kg) and moderate terminal elimination half-life ( t 1/2 λz = 166 ± 42 min). When TAN was given as a suspension (50 mg/kg), poor but erratic absolute oral bioavailability (mean value < 3.05%) was observed; however, when TAN was given in a solution prepared with randomly methylated-β-cyclodextrin (50 mg/kg), its plasma exposure was at least doubled (mean bioavailability: 6.02%). It was obvious that aqueous solubility hindered the oral absorption of TAN and acted as a barrier to its oral bioavailability. This study will facilitate further investigations on the medicinal potentials of TAN.

Fast determination of 3-ethenylpyridine as a marker of environmental tobacco smoke at trace level using direct atmospheric pressure chemical ionization tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Jiang, Cheng-Yong; Sun, Shi-Hao; Zhang, Qi-Dong; Liu, Jun-Hui; Zhang, Jian-Xun; Zong, Yong-Li; Xie, Jian-Ping

2013-03-01

A method with atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS/MS) was developed and applied to direct analysis of Environmental Tobacco Smoke (ETS), using 3-ethenylpyridine (3-EP) as a vapour-phase marker. In this study, the ion source of APCI-MS/MS was modified and direct analysis of gas sample was achieved by the modified instrument. ETS samples were directly introduced, via an atmospheric pressure inlet, into the APCI source. Ionization was carried out in positive-ion APCI mode and 3-EP was identified by both full scan mode and daughter scan mode. Quantification of 3-EP was performed by multiple reaction monitoring (MRM) mode. The calibration curve was obtained in the range of 1-250 ng L-1 with a satisfactory regression coefficient of 0.999. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.5 ng L-1 and 1.6 ng L-1, respectively. The precision of the method, calculated as relative standard deviation (RSD), was characterized by repeatability (RSD 3.92%) and reproducibility (RSD 4.81%), respectively. In real-world ETS samples analysis, compared with the conventional GC-MS method, the direct APCI-MS/MS has shown better reliability and practicability in the determination of 3-EP at trace level. The developed method is simple, fast, sensitive and repeatable; furthermore, it could provide an alternative way for the determination of other volatile pollutants in ambient air at low levels.

Preparation of three-dimensional mesoporous polymer in situ polymerization solid phase microextraction fiber and its application to the determination of seven chlorophenols.

PubMed

Wang, Xuemei; Wang, Huan; Huang, Pengfei; Ma, Xiaomin; Lu, Xiaoquan; Du, Xinzhen

2017-01-06

A superior solid-phase microextraction (SPME) fiber-coating material, three dimensional order mesoporous polymers with Ia-3d bicontinuous cubic structure (3D-OMPs) was in situ coated on a stainless steel wire by solvent evaporation induced self-assembly (EISA) and thermo-polymerization. Fourier-transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angel X-ray diffraction (SAXRD), N 2 adsorption-desorption transmission, and thermogravimetry analysis (TGA) were applied to the characterization of the synthesized 3D-OMPs coating. The performance and feasibility of the homemade fiber was evaluated through direct immersion (DI) SPME followed by high-performance liquid chromatography-UV detector (HPLC-UV) for the simultaneous extraction of seven chlorophenols in water samples. Under the optimum conditions, the prepared fiber exhibited excellent extraction properties as compared to three commercial fibers, the DI-SPME-HPLC-UV method showed low limits of detection (0.32-1.85μgL -1 ), wide linear ranges (5.0-1000μgL -1 ), and acceptable reproducibility (relative standard deviation, RSD<7.6% for one fiber, RSD<8.9% for fiber to fiber). Moreover, the method was further successfully applied to the analysis of seven CPs in real samples with good recoveries (80.5-99.5%) and satisfactory precisions (RSD<9.2%). It was confirmed that the proposed method has high sensitivity, outstanding selectivity and good reproducibility to the determination of trace CPs in the environmental water. Copyright © 2016 Elsevier B.V. All rights reserved.

Rsd family proteins make simultaneous interactions with regions 2 and 4 of the primary sigma factor

PubMed Central

Yuan, Andy H.; Gregory, Brian D.; Sharp, Josh S.; McCleary, Katherine D.; Dove, Simon L.; Hochschild, Ann

2008-01-01

Summary Bacterial anti-σ factors typically regulate σ factor function by restricting the access of their cognate σ factors to the RNA polymerase (RNAP) core enzyme. The E. coli Rsd protein forms a complex with the primary σ factor, σ70, inhibits σ70-dependent transcription in vitro, and has been proposed to function as a σ70-specific anti-σ factor, thereby facilitating the utilization of alternative σ factors. In prior work, Rsd has been shown to interact with conserved region 4 of σ70, but it is not known whether this interaction suffices to account for the regulatory functions of Rsd. Here we show that Rsd and the Rsd ortholog AlgQ, a global regulator of gene expression in P. aeruginosa, interact with conserved region 2 of σ70. We show further that Rsd and AlgQ can interact simultaneously with regions 2 and 4 of σ70. Our findings establish that the abilities of Rsd and AlgQ to interact with σ70 region 2 are important determinants of their in vitro and in vivo activities. PMID:18826409

Rsd family proteins make simultaneous interactions with regions 2 and 4 of the primary sigma factor.

PubMed

Yuan, Andy H; Gregory, Brian D; Sharp, Josh S; McCleary, Katherine D; Dove, Simon L; Hochschild, Ann

2008-12-01

Bacterial anti-sigma factors typically regulate sigma factor function by restricting the access of their cognate sigma factors to the RNA polymerase (RNAP) core enzyme. The Escherichia coli Rsd protein forms a complex with the primary sigma factor, sigma(70), inhibits sigma(70)-dependent transcription in vitro, and has been proposed to function as a sigma(70)-specific anti-sigma factor, thereby facilitating the utilization of alternative sigma factors. In prior work, Rsd has been shown to interact with conserved region 4 of sigma(70), but it is not known whether this interaction suffices to account for the regulatory functions of Rsd. Here we show that Rsd and the Rsd orthologue AlgQ, a global regulator of gene expression in Pseudomonas aeruginosa, interact with conserved region 2 of sigma(70). We show further that Rsd and AlgQ can interact simultaneously with regions 2 and 4 of sigma(70). Our findings establish that the abilities of Rsd and AlgQ to interact with sigma(70) region 2 are important determinants of their in vitro and in vivo activities.

Sensitive determination of tilmicosin, erythromycin ethylsuccinate and clindamycin by CE with electrochemiluminescence detection using azithromycin as internal standard and its applications.

PubMed

Liu, Yan-Ming; Shi, Yan-Mei; Liu, Zhuan-Li; Peng, Long-Fei

2010-05-01

A sensitive approach for the simultaneous determination of tilmicosin, erythromycin ethylsuccinate and clindamycin was developed by CE coupled with electrochemiluminescence detection with ionic liquid. The parameters for CE, electrochemiluminescence detection and the effect of ionic liquid were investigated systematically. The three analytes were well separated and detected within 8 min. The limits of detection (S/N=3) of tilmicosin, erythromycin ethylsuccinate and clindamycin are 3.4x10(-9), 2.3x10(-8) and 1.3x10(-8) mol/L, respectively. The precisions (RSD%) of the peak area and the migration time are from 0.8 to 1.5% and from 0.2 to 0.5% within a day and from 1.8 to 2.7% and from 0.6 to 0.8% in 3 days, respectively. The limits of quantitation (S/N=10) of tilmicosin, erythromycin ethylsuccinate and clindamycin are 3.2x10(-8), 2.9x10(-7) and 9.1x10(-8) mol/L in human urines and 5.5x10(-8), 3.2x10(-7) and 2.1x10(-7) mol/L in milk samples, respectively. The recoveries of three analytes at different concentration levels in urine, milk and drugs are between 90.0 and 104.7%. The proposed method was successfully applied to the determination of three analytes in human urine, milk and drugs.