Development of a novel pH sensor based upon Janus Green B immobilized on triacetyl cellulose membrane: Experimental design and optimization.

PubMed

Chamkouri, Narges; Niazi, Ali; Zare-Shahabadi, Vali

2016-03-05

A novel pH optical sensor was prepared by immobilizing an azo dye called Janus Green B on the triacetylcellulose membrane. Condition of the dye solution used in the immobilization step, including concentration of the dye, pH, and duration were considered and optimized using the Box-Behnken design. The proposed sensor showed good behavior and precision (RSD<5%) in the pH range of 2.0-10.0. Advantages of this optical sensor include on-line applicability, no leakage, long-term stability (more than 6 months), fast response time (less than 1 min), high selectivity and sensitivity as well as good reversibility and reproducibility. Copyright © 2015. Published by Elsevier B.V.

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.

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.

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.

[Spectrophotometric determination of piroxicam using ferric ferricyanide as reagent].

PubMed

Mândrescu, Mariana; Spac, A F; Dorneanu, V

2009-01-01

For the piroxicam determination (nonsteroidal antiinflammatory drug-NSAID) it was developed a spectrophotometric method, based on the reduction of ferric ferricyanide into ferro-ferricyanide (Prussian Blue), with maximum of absorbance at 760 nm. The practical working conditions were established. In the 0.2 divided by 2.0 microg/mL range of piroxicam concentration, were used the 2 mL of ferric ferricyanide 1 mL of 2N hydrocloric acid. To delay the flocculation of Prussian Blue it was to add a 1 mL solution of sodium lauryl sulfate 1%. After 15 minutes read the absorbance at 760 nm. The developed method was validated. The method showed a good linearity in the range of 0.2 divided by 2.0 microg/mL (the correlation coefficient r = 0.9995). The detection limit (LD) was 0.056 microg/mL and the quantification limit (LQ) was 0.18 microg/mL. There were established the system precision (RSD = 0.25%), the precison (RSD = 1.91%) and the accuracy-recovery in the range 98.21 divided by 104.92% with a mean recovery of 100.91%. The experimental results demonstrated a good sensibility. The specific absorptivity for this method is A(1 cm, 760 nm)(1%) = 4374 much higher than piroxicam in UV (A(1 cm, 330 nm)(1%) = 296)

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.

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

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.

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.

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.

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.

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.

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.

[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%.

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.

Comparing monolithic and fused core HPLC columns for fast chromatographic analysis of fat-soluble vitamins.

PubMed

Kurdi, Said El; Muaileq, Dina Abu; Alhazmi, Hassan A; Bratty, Mohammed Al; Deeb, Sami El

2017-06-27

HPLC stationary phases of monolithic and fused core type can be used to achieve fast chromatographic separation as an alternative to UPLC. In this study, monolithic and fused core stationary phases are compared for fast separation of four fat-soluble vitamins. Three new methods on the first and second generation monolithic silica RP-18e columns and a fused core pentafluoro-phenyl propyl column were developed. Application of three fused core columns offered comparable separations of retinyl palmitate, DL-α-tocopheryl acetate, cholecalciferol and menadione in terms of elution speed and separation efficiency. Separation was achieved in approx. 5 min with good resolution (Rs > 5) and precision (RSD ≤ 0.6 %). Monolithic columns showed, however, a higher number of theoretical plates, better precision and lower column backpressure than the fused core column. The three developed methods were successfully applied to separate and quantitate fat-soluble vitamins in commercial products.

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

Magnetic solid-phase extraction based on magnetic multiwalled carbon nanotubes for the simultaneous enantiomeric analysis of five β-blockers in the environmental samples by chiral liquid chromatography coupled with tandem mass spectrometry.

PubMed

Wang, Zhaokun; Zhang, Xue; Jiang, Shenmeng; Guo, Xingjie

2018-04-01

In this work, the magnetic multiwalled carbon nanotubes (Mag-MWCNTs) were prepared by self-assembly method and characterized by scanning electron microscopy, X-ray powder diffraction, energy dispersive X-ray and vibrating sample magnetometer. Then, these synthetic Mag-MWCNTs were used as sorbents to extract five β-blockers (atenolol, metoprolol, esmolol, pindolol and arotinolol) by magnetic solid-phase extraction. The target analytes adsorbed on Mag-MWCNTs were eluted and determined on a chiral α-acid glycoprotein column coupled with a triple quadrupole mass spectrometry. Eventually, the proposed method was applied to the analysis of the enantiomeric composition of the studied β-blockers in three environmental samples, including river water, influent wastewater and effluent wastewater. Method detection and quantification limits for all enantiomers were in the range of 0.50-1.45 and 1.63-3.75ng/L, respectively. Satisfactory recovery (82.9-95.6%), good intra-day precision (RSD 0.4-10.4%) and inter-day precision (RSD 2.9-7.4%) were also obtained. With numerous advantages such as simplicity of operation, rapidity and high enrichment factor, the newly developed method has potential to assess the enantioselectivity of chiral drugs in ecotoxicity and biodegradation processes, which is also a new expanded application of Mag-MWCNTs in the environmental analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Use of High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS) for Sequential Multi-Element Determination of Metals in Seawater and Wastewater Samples

NASA Astrophysics Data System (ADS)

Peña-Vázquez, E.; Barciela-Alonso, M. C.; Pita-Calvo, C.; Domínguez-González, R.; Bermejo-Barrera, P.

2015-09-01

The objective of this work is to develop a method for the determination of metals in saline matrices using high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Module SFS 6 for sample injection was used in the manual mode, and flame operating conditions were selected. The main absorption lines were used for all the elements, and the number of selected analytical pixels were 5 (CP±2) for Cd, Cu, Fe, Ni, Pb and Zn, and 3 pixels for Mn (CP±1). Samples were acidified (0.5% (v/v) nitric acid), and the standard addition method was used for the sequential determination of the analytes in diluted samples (1:2). The method showed good precision (RSD(%) < 4%, except for Pb (6.5%)) and good recoveries. Accuracy was checked after the analysis of an SPS-WW2 wastewater reference material diluted with synthetic seawater (dilution 1:2), showing a good agreement between certified and experimental results.

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

Bar adsorptive microextraction technique - application for the determination of pharmaceuticals in real matrices.

PubMed

Almeida, Carlos; Ahmad, Samir M; Nogueira, José Manuel F

2017-03-01

In the present work, bar adsorptive microextraction using miniaturized devices (7.5 × 3.0 mm) coated with suitable sorbent phases, combined with microliquid desorption (100 μL) followed by high-performance liquid chromatography with diode array detection (BAμE-μLD/HPLC-DAD), is proposed for the determination of trace level of six pharmaceuticals (furosemide, mebeverine, ketoprofen, naproxen, diclofenac and mefenamic acid) in environmental water and urine matrices. By comparing ten distinct sorbent materials (five polymeric and five activated carbons), the polymer P5 proved to be the most suitable to achieve the best selectivity and efficiency. The solvent volume minimization in the liquid desorption stage demonstrated remarkable effectiveness, being more environmentally friendly, and simultaneously increased the microextraction enrichment factor two-fold. Assays performed through BAμE(P5, 0.9 mg)-μLD(100 μL)/HPLC-DAD on 25 mL of ultrapure water samples spiked at the 4.0 μg/L level yielded average recoveries ranging from 91.4% (furosemide) to 101.0% (ketoprofen) with good precision (RSD < 10.6%), under optimized experimental conditions. The analytical performance showed convenient detection limits (25.0 - 120.0 ng/L), good linear dynamic ranges (0.1 to 24.0 μg/L), appropriate determination coefficients (r 2 > 0.9983), and excellent repeatability through intraday (RSD < 10.4%)) and interday (RSD < 10.0%) assays. By using the standard addition methodology, the application of the present analytical approach on environmental waters and urine samples revealed the occurrence of trace levels of some pharmaceuticals. The solvent minimization during the back-extraction step associated with the miniaturization of BAμE devices proved to be a very promising analytical technology for static microextraction analysis. Graphical abstract BAμE operating under the floating sampling technology for the determination of pharmaceuticals in aqueous media.

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.

A volatile tracer-assisted headspace analytical technique for determining the swelling capacity of superabsorbent polymers.

PubMed

Zhang, Shu-Xin; Jiang, Ran; Chai, Xin-Sheng

2017-09-01

This paper reports on a new method for the determination of swelling capacity of superabsorbent polymers by a volatile tracer-assisted headspace gas chromatography (HS-GC). Toluene was used as a tracer and added to the solution for polymers swelling test. Based on the differences of the tracer partitioned between the vapor and hydrogel phase before and after the polymer's swelling capacity, a transition point (corresponding to the material swelling capacity) can be observed when plotting the GC signal of toluene vs. the ratio of solution added to polymers. The present method has good precision (RSD<2.1%) and good accuracy, in which the relative deference between the data measured by the HS-GC method and the reference method were within 8.0%. The present method is very suitable to be used for testing the swelling capacity of polymers at the elevated temperatures. Copyright © 2017 Elsevier B.V. All rights reserved.

Development and Validation of GC-ECD Method for the Determination of Metamitron in Soil

PubMed Central

Tandon, Shishir; Kumar, Satyendra; Sand, N. K.

2015-01-01

This paper aims at developing and validating a convenient, rapid, and sensitive method for estimation of metamitron from soil samples.Determination andquantification was carried out by Gas Chromatography on microcapillary column with an Electron Capture Detector source. The compound was extracted from soil using methanol and cleanup by C-18 SPE. After optimization, the method was validated by evaluating the analytical curves, linearity, limits of detection, and quantification, precision (repeatability and intermediate precision), and accuracy (recovery). Recovery values ranged from 89 to 93.5% within 0.05- 2.0 µg L−1 with average RSD 1.80%. The precision (repeatability) ranged from 1.7034 to 1.9144% and intermediate precision from 1.5685 to 2.1323%. Retention time was 6.3 minutes, and minimum detectable and quantifiable limits were 0.02 ng mL−1 and 0.05 ng g−1, respectively. Good linearity (R 2 = 0.998) of the calibration curves was obtained over the range from 0.05 to 2.0 µg L−1. Results indicated that the developed method is rapid and easy to perform, making it applicable for analysis in large pesticide monitoring programmes. PMID:25733978

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.

Development of andrographolide molecularly imprinted polymer for solid-phase extraction

NASA Astrophysics Data System (ADS)

Yin, Xiaoying; Liu, Qingshan; Jiang, Yifan; Luo, Yongming

2011-06-01

A method employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE) to pretreat samples was developed. The polymers were prepared by precipitation polymerization with andrographolide as template molecule. The structure of MIP was characterized and its static adsorption capacity was measured by the Scatchard equation. In comparison with C 18-SPE and non-imprinted polymer (NIP) SPE column, MIP-SPE column displays high selectivity and good affinity for andrographolide and dehydroandrographolide for extract of herb Andrographis paniculata ( Burm.f.) Nees (APN). MIP-SPE column capacity was 11.9 ± 0.6 μmol/g and 12.1 ± 0.5 μmol/g for andrographolide and dehydroandrographolide, respectively and was 2-3 times higher than that of other two columns. The precision and accuracy of the method developed were satisfactory with recoveries between 96.4% and 103.8% (RSD 3.1-4.3%, n = 5) and 96.0% and 104.2% (RSD 2.9-3.7%, n = 5) for andrographolide and dehydroandrographolide, respectively. Various real samples were employed to confirm the feasibility of method. This developed method demonstrates the potential of molecularly imprinted solid phase extraction for rapid, selective, and effective sample pretreatment.

Rapid Quantification of N-Methyl-2-pyrrolidone in Polymer Matrices by Thermal Desorption-GC/MS.

PubMed

Kim, Young-Min; Kim, Jae Woo; Moon, Hye Mi; Lee, Min-Jin; Hosaka, Akihiko; Watanabe, Atsushi; Teramae, Norio; Park, Young-Kwon; Myung, Seung-Woon

2017-01-01

Analysis of a residual solvent in polymeric materials has become an important issue due to the increased regulations and standards for its use. N-Methyl-2-pyrrolidone (NMP) is a solvent widely used in many industries and restricted as one of the chemicals under EU REACH regulations due to its potential harmful effects. In this study, thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) is applied for the quantitative analysis of NMP with the use of a polymer-coated sample cup. By using the polymer-coated sample cup, the vaporization of NMP was prevented during waiting time before TD-GC/MS analysis. The calibration curve for the TD method showed good linearity (correlation coefficient, r 2 = 0.9998) and precision values (below 5.3% RSD). NMP recovery rates in different polymer matrices (PS, PMMA and PVC) were in the range of 98.8 to 106.6% with RSD values below 5.0%. The quantification result (600 mg NMP/kg PVC) for the blind NMP carrying sample in a PVC matrix by TD-GC/MS was higher than that (532 mg NMP/kg PVC) by solvent extraction-GC/MS method.

Determination of ketamine and its main metabolites by liquid chromatography coupled to tandem mass spectrometry in pig plasma: Comparison of extraction methods.

PubMed

Ramiole, Cindy; D'Hayer, Benoit; Boudy, Vincent; Legagneux, Josette; Fonsart, Julien; Houzé, Pascal

2017-11-30

A rapid, sensitive and specific liquid chromatography coupled to tandem mass spectrometry method was developed for the simultaneous quantification pig plasma of ketamine and its two principal metabolites, norketamine and dehydronorketamine. Three extraction procoles were assessed including acetonitrile precipitation, Oase™ microplate extraction, and liquid-liquid extraction. Oase™ microplate extraction induced no significant matrix effect, important signal/noise ratio and good recoveries, ranging from 82 to 87% for the considered compounds. Using this extraction procedure, the assay was linear in the dynamic range 10-3000ng/mL (R 2 >0.99) regardless of the analytes. Intra- and inter-day accuracies were less than 12% for all compounds and intra- and inter-day precisions expressed as RSD were within <9.9%. Samples were stable in different storage conditions. High ketamine, norketamine and dehydronorketamine concentrations up to 15,000ng/mL can be determined with good precision using appropriate sample dilution. The assay was successfully applied to pig plasma samples to determine the pharmacokinetics of ketamine and the consecutive metabolites after buccal administration of a 4mg/kg ketamine base solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

Detailed phenolic composition of Vidal grape pomace by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

PubMed

Luo, Lanxin; Cui, Yan; Zhang, Shuting; Li, Lingxi; Suo, Hao; Sun, Baoshan

2017-11-15

Vidal Blanc grape (Vitis vinifera cv.) is the predominant white grape variety used for the production of icewine in China's Liaoning province. In this paper, the development and validation of the method by ultrahigh-performance liquid chromatography-tandem mass spectrometry has been performed for determination of the detailed phenolic composition in the skin, seed and stem of Vidal grapes. The validation of the method was realized by calculating the linearity, repeatability, precision, stability and the limits of detection (LOD) and quantification (LOQ) of standard solutions. All the curves exhibited good linearity (r 2 >0.9997) and the LOD and LOQ were in the range of 0.002-0.025 and 0.006-0.086μg/ml, respectively. Good repeatability (RSD<4.3%) and stability (RSD<3.7%) were also found. Results confirmed that the developed method was more effective and sensitive for simultaneous determination of the major phenolic compounds in Vidal grape pomace. The optimized and validated method of ultrahigh-performance liquid chromatography tandem two complementary techniques, fourier transform ion cyclotron resonance mass spectrometry and triple-quadrupole mass spectrometry, allowed to identify and quantify up to 35 phenolic compounds in Vidal grape pomace, which has, as far as we know, been reported this grapevine variety for the first time. Seeds, skins and stems exhibited different qualitative and quantitative phenolic profiles. These results provided useful information for recovery of phenolic antioxidants from different parts of icewine pomace. Copyright © 2017. Published by Elsevier B.V.

Development and validation of an LC-UV method for the determination of sulfonamides in animal feeds.

PubMed

Kumar, P; Companyó, R

2012-05-01

A simple LC-UV method was developed for the determination of residues of eight sulfonamides (sulfachloropyridazine, sulfadiazine, sulfadimidine, sulfadoxine, sulfamethoxypyridazine, sulfaquinoxaline, sulfamethoxazole, and sulfadimethoxine) in six types of animal feed. C18, Oasis HLB, Plexa and Plexa PCX stationary phases were assessed for the clean-up step and the latter was chosen as it showed greater efficiency in the clean-up of interferences. Feed samples spiked with sulfonamides at 2 mg/kg were used to assess the trueness (recovery %) and precision of the method. Mean recovery values ranged from 47% to 66%, intra-day precision (RSD %) from 4% to 15% and inter-day precision (RSD %) from 7% to 18% in pig feed. Recoveries and intra-day precisions were also evaluated in rabbit, hen, cow, chicken and piglet feed matrices. Calibration curves with standards prepared in mobile phase and matrix-matched calibration curves were compared and the matrix effects were ascertained. The limits of detection and quantification in the feeds ranged from 74 to 265 µg/kg and from 265 to 868 µg/kg, respectively. Copyright © 2011 John Wiley & Sons, Ltd.

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

In situ ionic liquid dispersive liquid-liquid microextraction coupled to gas chromatography-mass spectrometry for the determination of organophosphorus pesticides.

PubMed

Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

2018-07-20

Nine organophosphorus pesticides (OPPs) were determined in environmental waters from different origins using in situ ionic liquid dispersive liquid microextraction (IL-DLLME). This preconcentration technique was coupled to gas chromatography-mass spectrometry (GC-MS) using microvial insert thermal desorption, an approach that uses a thermal desorption injector as sample introduction system. The parameters affecting both the microextraction and sample injection steps were optimized. The proposed method showed good precision, with RSD values ranging from 4.1 to 9.7%, accuracy with recoveries in the 85-118% range, and sensitivity with DLs ranging from 5 to 16 ng L -1 . Copyright © 2017 Elsevier B.V. All rights reserved.

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

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.

Discerning some Tylenol brands using attenuated total reflection Fourier transform infrared data and multivariate analysis techniques.

PubMed

Msimanga, Huggins Z; Ollis, Robert J

2010-06-01

Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to classify acetaminophen-containing medicines using their attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectra. Four formulations of Tylenol (Arthritis Pain Relief, Extra Strength Pain Relief, 8 Hour Pain Relief, and Extra Strength Pain Relief Rapid Release) along with 98% pure acetaminophen were selected for this study because of the similarity of their spectral features, with correlation coefficients ranging from 0.9857 to 0.9988. Before acquiring spectra for the predictor matrix, the effects on spectral precision with respect to sample particle size (determined by sieve size opening), force gauge of the ATR accessory, sample reloading, and between-tablet variation were examined. Spectra were baseline corrected and normalized to unity before multivariate analysis. Analysis of variance (ANOVA) was used to study spectral precision. The large particles (35 mesh) showed large variance between spectra, while fine particles (120 mesh) indicated good spectral precision based on the F-test. Force gauge setting did not significantly affect precision. Sample reloading using the fine particle size and a constant force gauge setting of 50 units also did not compromise precision. Based on these observations, data acquisition for the predictor matrix was carried out with the fine particles (sieve size opening of 120 mesh) at a constant force gauge setting of 50 units. After removing outliers, PCA successfully classified the five samples in the first and second components, accounting for 45.0% and 24.5% of the variances, respectively. The four-component PLS-DA model (R(2)=0.925 and Q(2)=0.906) gave good test spectra predictions with an overall average of 0.961 +/- 7.1% RSD versus the expected 1.0 prediction for the 20 test spectra used.

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.

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.

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

Development of an LC-MS/MS method for the determination of endogenous cortisol in hair using (13)C3-labeled cortisol as surrogate analyte.

PubMed

Binz, Tina M; Braun, Ueli; Baumgartner, Markus R; Kraemer, Thomas

2016-10-15

Hair cortisol levels are increasingly applied as a measure for stress in humans and mammals. Cortisol is an endogenous compound and is always present within the hair matrix. Therefore, "cortisol-free hair matrix" is a critical point for any analytical method to accurately quantify especially low cortisol levels. The aim of this project was to modify current methods used for hair cortisol analysis to more accurately determine low endogenous cortisol concentrations in hair. For that purpose, (13)C3-labeled cortisol, which is not naturally present in hair (above 13C natural abundance levels), was used for calibration and comparative validation applying cortisol versus (13)C3-labeled cortisol. Cortisol was extracted from 20mg hair (standard sample amount) applying an optimized single step extraction protocol. An LC-MS/MS method was developed for the quantitative analysis of cortisol using either cortisol or (13)C3-cortisol as calibrators and D7-cortisone as internal standard (IS). The two methods (cortisol/(13)C3-labeled cortisol) were validated in a concentration range up to 500pg/mg and showed good linearity for both analytes (cortisol: R(2)=0.9995; (13)C3-cortisol R(2)=0.9992). Slight differences were observed for limit of detection (LOD) (0.2pg/mg/0.1pg/mg) and limit of quantification (LOQ) (1pg/mg/0.5pg/mg). Precision was good with a maximum deviation of 8.8% and 10% for cortisol and (13)C3-cortisol respectively. Accuracy and matrix effects were good for both analytes except for the quality control (QC) low cortisol. QC low (2.5pg/mg) showed matrix effects (126.5%, RSD 35.5%) and accuracy showed a deviation of 26% when using cortisol to spike. These effects are likely to be caused by the unknown amount of endogenous cortisol in the different hair samples used to determine validation parameters like matrix effect, LOQ and accuracy. No matrix effects were observed for the high QC (400pg/mg) samples. Recovery was good with 92.7%/87.3% (RSD 9.9%/6.2%) for QC low and 102.3%/82.1% (RSD 5.8%/11.4%) for QC high. After successful validation the applicability of the method could be proven. The study shows that the method is especially useful for determining low endogenous cortisol concentrations as they occur in cow hair for example. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous Determination of Ofloxacin and Flavoxate Hydrochloride by Absorption Ratio and Second Derivative UV Spectrophotometry

PubMed Central

Attimarad, Mahesh

2010-01-01

The objective of this study was to develop simple, precise, accurate and sensitive UV spectrophotometric methods for the simultaneous determination of ofloxacin (OFX) and flavoxate HCl (FLX) in pharmaceutical formulations. The first method is based on absorption ratio method, by formation of Q absorbance equation at 289 nm (λmax of OFX) and 322.4 nm (isoabsorptive point). The linearity range was found to be 1 to 30 μg/ml for FLX and OFX. In the method-II second derivative absorption at 311.4 nm for OFX (zero crossing for FLX) and at 246.2 nm for FLX (zero crossing for OFX) was used for the determination of the drugs and the linearity range was found to be 2 to 30 μg/ml for OFX and 2-75 μg /ml for FLX. The accuracy and precision of the methods were determined and validated statistically. Both the methods showed good reproducibility and recovery with % RSD less than 1.5%. Both the methods were found to be rapid, specific, precise and accurate and can be successfully applied for the routine analysis of OFX and FLX in combined dosage form PMID:24826003

[HPLC method to determine DEHP released into blood from a disposable extracorporeal circulation tube].

PubMed

Liu, Xi; Yu, Jingjing; Li, Shen; Wang, Hong; Liu, Jiaxin

2013-08-01

We used blood as leaching medium, simulating clinical operation under maximum condition, to develop Liquid-phase extraction- High Performance Liquid Chromatography (HPLC) method for determination of plasticizer Di-(2-ethylhexyl)phthalate (DEHP) released from Disposable Extracorporeal Circulation Tube in order to lay the foundation of risk analysis of this product. The characteristic wavelength of DEHP in methanol was detected. Acetonitrile was added to the leaching blood in proportion and extracted DEHP from blood. The methodology for HPLC to quantify DEHP was established and the DEHP amount released from this disposable extracorporeal circulation tube was measured. The experiments showed good results as follows. The characteristic wavelength of DEHP was 272nm. The concentration of DEHP (5-250 microg/mL) kept good linear relationship with peak area (r=0.9999). Method sensitivity was 1 microg/mL. Precisions showed RSD<5%. The adding standard extraction Recovery Rates of 25, 100 and 250 microg DEHP standard were 61.91 +/- 3.32)%, (69.38 +/- 0.55)% and (68.47 +/- 1.15)%. The DEHP maximum amounts released from 3 sets of this disposable extracorporeal circulation tube were 204.14, 106.30 and 165.34 mg/set. Our Liquid-phase Extraction-HPLC method showed high accuracy and precision, and relatively stable recovery rate. Its operation was also convenient.

Simultaneous Chloramphenicol and Florfenicol Determination by A Validated DLLME-HPLC-UV Method in Pasteurized Milk.

PubMed

Karami-Osboo, Rouhollah; Miri, Ramin; Javidnia, Katayoun; Kobarfard, Farzad

2016-01-01

The antibiotic residues in milk are a well-known serious problem and pose several health hazards to consumers. We have described a simple, rapid, and inexpensive DLLME-HPLC/UV technique for the extraction of chloramphenicol and florfenicol residues in milk samples. Under the optimum conditions, linearity of the method was observed over the range 0.02-0.85 µg/L with correlation coefficients > 0.999. The proposed method has been found to have a good limit of detection (signal to noise ratio = 3) for chloramphenicol (12.5 µg/Kg) and florfenicol (12.2 µg/Kg), and precision with relative standard deviation values under 15% (RSD, n = 3). Good recoveries (69.1-79.4%) were obtained for the extraction of the target analytes in milk samples. This simple and economic method has been applied for analyses of 15 real milk samples. Among all samples only one of them was contaminated to florfenicol; 62.4 µg/Kg and contamination to chloramphenicol was not detected.

Simultaneous Chloramphenicol and Florfenicol Determination by A Validated DLLME-HPLC-UV Method in Pasteurized Milk

PubMed Central

Karami-Osboo, Rouhollah; Miri, Ramin; Javidnia, Katayoun; Kobarfard, Farzad

2016-01-01

The antibiotic residues in milk are a well-known serious problem and pose several health hazards to consumers. We have described a simple, rapid, and inexpensive DLLME-HPLC/UV technique for the extraction of chloramphenicol and florfenicol residues in milk samples. Under the optimum conditions, linearity of the method was observed over the range 0.02-0.85 µg/L with correlation coefficients > 0.999. The proposed method has been found to have a good limit of detection (signal to noise ratio = 3) for chloramphenicol (12.5 µg/Kg) and florfenicol (12.2 µg/Kg), and precision with relative standard deviation values under 15% (RSD, n = 3). Good recoveries (69.1–79.4%) were obtained for the extraction of the target analytes in milk samples. This simple and economic method has been applied for analyses of 15 real milk samples. Among all samples only one of them was contaminated to florfenicol; 62.4 µg/Kg and contamination to chloramphenicol was not detected. PMID:27980571

Coupling solid-phase microextraction and high-performance liquid chromatography for direct and sensitive determination of halogenated fungicides in wine.

PubMed

Millán, S; Sampedro, M C; Unceta, N; Goicolea, M A; Rodríguez, E; Barrio, R J

2003-05-02

A solid-phase microextraction (SPME) method coupled to high-performance liquid chromatography with diode array detection (HPLC-DAD) for the analysis of six organochlorine fungicides (nuarimol, triadimenol, triadimefon, folpet, vinclozolin and penconazole) in wine was developed. For this purpose, polydimethylsiloxane-divinylbenzene-coated fibers were utilized and all factors affecting throughput, precision, and accuracy of the SPME method were investigated and optimized. These factors include: matrix influence, extraction and desorption time, percentage of ethanol, pH, salt effect and desorption mode. The performed analytical procedure showed detectability ranging from 4 to 27 microg l(-1) and precision from 2.4 to 14.2% (as intra-day relative standard deviation, RSD) and 4.7-25.7% (as inter-day RSD) depending on the fungicide. The results demonstrate the suitability of the SPME-HPLC-DAD method to analyze these organochlorine fungicides in red wine.

Capabilities and limitations of dispersive liquid-liquid microextraction with solidification of floating organic drop for the extraction of organic pollutants from water samples.

PubMed

Vera-Avila, Luz E; Rojo-Portillo, Tania; Covarrubias-Herrera, Rosario; Peña-Alvarez, Araceli

2013-12-17

Dispersive liquid-liquid microextraction with solidification of floating organic drop (DLLME-SFO) is one of the most interesting sample preparation techniques developed in recent years. Although several applications have been reported, the potentiality and limitations of this simple and rapid extraction technique have not been made sufficiently explicit. In this work, the extraction efficiency of DLLME-SFO for pollutants from different chemical families was determined. Studied compounds include: 10 polycyclic aromatic hydrocarbons, 5 pesticides (chlorophenoxy herbicides and DDT), 8 phenols and 6 sulfonamides, thus, covering a large range of polarity and hydrophobicity (LogKow 0-7, overall). After optimization of extraction conditions using 1-dodecanol as extractant, the procedure was applied for extraction of each family from 10-mL spiked water samples, only adjusting sample pH as required. Absolute recoveries for pollutants with LogKow 3-7 were >70% and recovery values within this group (18 compounds) were independent of structure or hydrophobicity; the precision of recovery was very acceptable (RSD<12%) and linear behavior was observed in the studied concentration range (r(2)>0.995). Extraction recoveries for pollutants with LogKow 1.46-2.8 were in the range 13-62%, directly depending on individual LogKow values; however, good linearity (r(2)>0.993) and precision (RSD<6.5%) were also demonstrated for these polar solutes, despite recovery level. DLLME-SFO with 1-dodecanol completely failed for extraction of compounds with LogKow≤1 (sulfa drugs), other more polar extraction solvents (ionic liquids) should be explored for highly hydrophilic pollutants. Copyright © 2013 Elsevier B.V. All rights reserved.

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.

Spectrophotometric determination of ofloxacin in pharmaceuticals by redox reaction

NASA Astrophysics Data System (ADS)

Ramesh, P. J.; Basavaiah, K.; Rajendraprasad, N.; Devi, O. Zenita; Vinay, K. B.

2011-07-01

Two simple spectrophotometric methods have been developed to analyze ofloxacin (OFX) in pharmaceuticals. The methods are based on the oxidation of OFX by a measured excess of cerium(IV) sulfate in H2SO4 medium. This was followed by the determination of the unreacted oxidant by reacting it with either p-toluidine ( p-TD) and measuring the absorbance at 525 nm (method A) or o-dianisidine ( o-DA) and measuring the absorbance at 470 nm (method B). In both methods, the amount of cerium(IV) sulfate reacted corresponds to the amount of OFX. Calibration graphs were linear over the ranges of 0-120 and 0-4 g/ml OFX for methods A and B, respectively. The calculated molar absorptivity (2.34ṡ103 and 5.99ṡ104), Sandell sensitivity, and limit of quantification for the methods are reported. The intra-day precision (%RSD) and accuracy (%RE) were < 8.0 and ≤ 4.0%, respectively, and the inter-day RSD and RE values were within 5 and 4.0%, respectively. The applicability of the methods was demonstrated by determining OFX in tablets with an accuracy (%RE) of < 3% and precision (%RSD) of ≤2.65%. The accuracy of the methods was further ascertained by recovery experiments via a standard-addition procedure.

Analysis of total copper, cadmium and lead in refuse-derived fuels (RDF): study on analytical errors using synthetic samples.

PubMed

Skutan, Stefan; Aschenbrenner, Philipp

2012-12-01

Components with extraordinarily high analyte contents, for example copper metal from wires or plastics stabilized with heavy metal compounds, are presumed to be a crucial source of errors in refuse-derived fuel (RDF) analysis. In order to study the error generation of those 'analyte carrier components', synthetic samples spiked with defined amounts of carrier materials were mixed, milled in a high speed rotor mill to particle sizes <1 mm, <0.5 mm and <0.2 mm, respectively, and analyzed repeatedly. Copper (Cu) metal and brass were used as Cu carriers, three kinds of polyvinylchloride (PVC) materials as lead (Pb) and cadmium (Cd) carriers, and paper and polyethylene as bulk components. In most cases, samples <0.2 mm delivered good recovery rates (rec), and low or moderate relative standard deviations (rsd), i.e. metallic Cu 87-91% rec, 14-35% rsd, Cd from flexible PVC yellow 90-92% rec, 8-10% rsd and Pb from rigid PVC 92-96% rec, 3-4% rsd. Cu from brass was overestimated (138-150% rec, 13-42% rsd), Cd from flexible PVC grey underestimated (72-75% rec, 4-7% rsd) in <0.2 mm samples. Samples <0.5 mm and <1 mm spiked with Cu or brass produced errors of up to 220% rsd (<0.5 mm) and 370% rsd (<1 mm). In the case of Pb from rigid PVC, poor recoveries (54-75%) were observed in spite of moderate variations (rsd 11-29%). In conclusion, time-consuming milling to <0.2 mm can reduce variation to acceptable levels, even given the presence of analyte carrier materials. Yet, the sources of systematic errors observed (likely segregation effects) remain uncertain.

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.

High Performance Liquid Chromatography-Diode Array Detector Method for the Simultaneous Determination of Five Compounds in the Pulp and Seed of Sea Buckthorn.

PubMed

Zhao, Lu; Wen, E; Upur, Halmuart; Tian, Shuge

2017-01-01

Sea buckthorn ( Hippophae rhamnoides L.) as a traditional Chinese medicinal plant has various uses in Xinjiang. A reversed-phase rapid-resolution liquid-chromatography method with diode array detector was developed for simultaneous determination of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the pulp and seed of sea buckthorn, a widely used traditional Chinese medicine for promoting metabolism and treating scurvy and other diseases. Compounds were separated on an Agilent ZORBAX SB-C18 column (4.6 mm × 250 mm, 5 μm; USA) with gradient elution using methanol and 0.4% phosphoric acid (v/v) at 1.0 mL/min. Detection wavelength was set at 280 nm. The fruits of wild sea buckthorn were collected from Wushi County in Aksu, Xinjiang Province. The RSD of precision test of the five compounds were in the range of 0.60-2.22%, and the average recoveries ranged from 97.36% to 101.19%. Good linearity between specific chromatographic peak and component qualities were observed in the investigated ranges for all the analytes ( R 2 > 0.9997). The proposed method was successfully applied to determine the levels of five active components in sea buckthorn samples from Aksu in Xinjiang. The proposed method is simple, fast, sensitive, accurate, and suitable for quantitative assessment of the pulp and seed of sea buckthorn. Quantitative analysis method of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the extract of sea buckthorn pulp and seed is developed by high-performance liquid chromatography (HPLC) diode array detection.This method is simple and accurate; has strong specificity, good precision, and high recovery rate; and provides a reliable basis for further development of the substances in the pulp and seed of sea buckthorn.The method is widely used for content determination of active ingredients or physiologically active components in traditional Chinese medicine and its preparation Abbreviation used: PR: protocatechuic acid, RU: rutin, QU: quercetin, KA: kaempferol, IS: isorhamnetin, HPLC: high-performance liquid chromatography, HPLC-DAD: high performance liquid chromatographydiode array detector, LOD: linearity and limit of detection, LOQ: limit of quantitation, RSD: relative standard deviation.

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 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.

[Determination of 5 nucleosides components in culture of Paecilomyces hepialid by HPLC].

PubMed

Yang, Dan; Ma, Yun-shu; Huang, Ting-ting; Chen, Cheng

2015-08-01

The concentration of 5 nucleosides, uracil, uridine, guanidine, adenine and adenosine in culture of Paecilomyces hepialid was determined by the developed method of HPLC. The HPLC method was performed on a Waters SunFire C18 (4.6 mm x 250 mm, 5 μm) column with methanol-water gradient elution as the mobile phase. The detection wavelength was 260 nm and the colunmn temperature was controlled at 30 °C. The linear range was 10.00-200.00 mg · L(-1) (r = 0.9994) for uracil, 10.10-202.00 mg · L(-1) (r = 0.9992) for uridine, 10.00-200.00 mg · L(-1) (r = 0.9991) for guanidine, 10.30-206.00 mg · L(-1) (r = 0.9992) for adenine and 10.45-209.00 mg · L(-1) (r = 0.9991) for adenosine, respectively. The RSD of precision was 0.032%, 0.035%, 0.039%, 0.049%, 0.00080%, respectively. The average recoveries of uracil, guanidine, adenine, and adenosine were 97.34%, 99.10%, 101.6%, 98.61% and 100.2% with RSD of 1.3%, 2.1%, 0.96%, 0.95%, and 1.3% respectively. The method showed high sensitivity, good selectivity, linearity and repeatability, which was suitable for the content analysis of 5 nucleosides components in P. hepialid and its extracts.

A feasible, economical, and accurate analytical method for simultaneous determination of six alkaloid markers in Aconiti Lateralis Radix Praeparata from different manufacturing sources and processing ways.

PubMed

Zhang, Yi-Bei; DA, Juan; Zhang, Jing-Xian; Li, Shang-Rong; Chen, Xin; Long, Hua-Li; Wang, Qiu-Rong; Cai, Lu-Ying; Yao, Shuai; Hou, Jin-Jun; Wu, Wan-Ying; Guo, De-An

2017-04-01

Aconiti Lateralis Radix Praeparata (Fuzi) is a commonly used traditional Chinese medicine in clinic for its potency in restoring yang and rescuing from collapse. Aconiti alkaloids, mainly including monoester-diterpenoidaconitines (MDAs) and diester-diterpenoidaconitines (DDAs), are considered to act as both bioactive and toxic constituents. In the present study, a feasible, economical, and accurate HPLC method for simultaneous determination of six alkaloid markers using the Single Standard for Determination of Multi-Components (SSDMC) method was developed and fully validated. Benzoylmesaconine was used as the unique reference standard. This method was proven as accurate (recovery varying between 97.5%-101.8%, RSD < 3%), precise (RSD 0.63%-2.05%), and linear (R > 0.999 9) over the concentration ranges, and subsequently applied to quantitative evaluation of 62 batches of samples, among which 45 batches were from good manufacturing practice (GMP) facilities and 17 batches from the drug market. The contents were then analyzed by principal component analysis (PCA) and homogeneity test. The present study provided valuable information for improving the quality standard of Aconiti Lateralis Radix Praeparata. The developed method also has the potential in analysis of other Aconitum species, such as Aconitum carmichaelii (prepared parent root) and Aconitum kusnezoffii (prepared root). Copyright © 2017 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

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

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.

Semiautomated solid-phase extraction manifold with a solvent-level sensor.

PubMed

Orlando, R M; Rath, S; Rohwedder, J J R

2013-11-15

A semiautomated solid-phase extraction manifold for multiple extractions is presented. The manifold utilizes commercial solid-phase syringe cartridges and automatically introduces and elutes all the solvents during the extraction, reducing the typical workload and stress of the analyst. The manifold consists of a peristaltic pump with solenoid valves in a flow circuit that contains transmissive photomicrosensors. The photomicrosensors were used to control the solvent dispenser and the solvent level inside the cartridge. As solvent-level sensors, the photomicrosensors determined the exact time the solvent reached the top frit to avoid sorbent drying and accurately perform the solvent exchange. The repeatability of the manifold to introduce a particular volume of solvent into the cartridges was measured, and the precisions were between 0.05 and 2.89% (RSD). To evaluate the manifold, the amount of two fluoroquinolones in a fortified blank milk sample was determined. The results of the intra- and inter-day precision of multiple extractions from the fortified milk samples resulted in precisions better than 9.0% (RSD) and confirmed that the arrangement of the semiautomated manifold could adequately be used in solid-phase extraction with commercial cartridges. Copyright © 2013 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.

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.

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.

Enantioselective determination of metconazole in multi matrices by high-performance liquid chromatography.

PubMed

He, Rujian; Fan, Jun; Tan, Qi; Lai, Yecai; Chen, Xiaodong; Wang, Tai; Jiang, Ying; Zhang, Yaomou; Zhang, Weiguang

2018-02-01

A reliable and effective HPLC analytical method has been developed to stereoselectively quantify metconazole in soil and flour matrices. Effects of polysaccharide chiral stationary phase, type and content of alcoholic modifier on separation of racemic metconazole have been discussed in detail. Resolution and quantitative determination of metconazole stereoisomers were performed by using an Enantiopak OD column, with the n-hexane-ethanol mixture (97:3, v/v) at the flow rate of 1.0mL/min. Then, extraction and cleanup procedures followed by the modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method were used for metconazole racemate in soil and flour matrices. The residual analysis method was validated. Good linearity (R 2 ≥ 0.9997) and recoveries (94.98-104.89%, RSD ≤ 2.0%) for four metconazole stereoisomers were obtained. In brief, this proposed method showed good accuracy and precision, which might be applied in enantioselective determination, residual quantitative analysis, and degradation of metconazole in food and environmental matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of parabens using two microextraction methods coupled with capillary liquid chromatography-UV detection.

PubMed

Chen, Chen-Wen; Hsu, Wen-Chan; Lu, Ya-Chen; Weng, Jing-Ru; Feng, Chia-Hsien

2018-02-15

Parabens are common preservatives and environmental hormones. As such, possible detrimental health effects could be amplified through their widespread use in foods, cosmetics, and pharmaceutical products. Thus, the determination of parabens in such products is of particular importance. This study explored vortex-assisted dispersive liquid-liquid microextraction techniques based on the solidification of a floating organic drop (VA-DLLME-SFO) and salt-assisted cloud point extraction (SA-CPE) for paraben extraction. Microanalysis was performed using a capillary liquid chromatography-ultraviolet detection system. These techniques were modified successfully to determine four parabens in 19 commercial products. The regression equations of these parabens exhibited good linearity (r 2 =0.998, 0.1-10μg/mL), good precision (RSD<5%) and accuracy (RE<5%), reduced reagent consumption and reaction times (<6min), and excellent sample versatility. VA-DLLME-SFO was also particularly convenient due to the use of a solidified extract. Thus, the VA-DLLME-SFO technique was better suited to the extraction of parabens from complex matrices. Copyright © 2017 Elsevier Ltd. All rights reserved.

Down scaled Kjeldahl digestion and flow injection conductometric system for determination of protein content in some traditional northern Thai foods.

PubMed

Yanu, Pattama; Jakmunee, Jaroon

2017-09-01

A flow injection conductometric (FIC) system for determination of total Kjeldahl nitrogen (TKN) was developed for estimating total protein content in food. A small scale Kjeldahl digestion was performed with a short digestion time of only 20min. The digested solution was injected into the FIC system, and TKN was converted to ammonia gas in an alkaline donor stream of the system. The gas diffused through a membrane and dissolved into an acceptor stream causing an increase in conductivity as detected by a detector and recorded as a peak. Under the optimum condition, a linear calibration graph in the range of 4.00-100.00mgL -1 was obtained with LOD of 0.05mgL -1 . A good precision (0.04% RSD, n=11, 30.00mgNL -1 ) and high sample throughput of 72h -1 was achieved. The method was applied for determination of protein in some traditional northern Thai foods, revealing that they are good sources of proteins. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analytical determination of flavonoids aimed to analysis of natural samples and active packaging applications.

PubMed

Castro-López, María del Mar; López-Vilariño, José Manuel; González-Rodríguez, María Victoria

2014-05-01

Several HPLC and UHPLC developed methods were compared to analyse the natural antioxidants catechins and quercetin used in active packaging and functional foods. Photodiode array detector coupled with a fluorescence detector and compared with LTQ-Orbitrap-MS was used. UHPLC was investigated as quick alternative without compromising the separation, analysis time shortened up to 6-fold. The feasibility of the four developed methods was compared. Linearity up to 0.9995, low detection limits (between 0.02 and 0.7 for HPLC-PDA, 2 to 7-fold lower for HPLC- LTQ-Orbitrap-MS and from 0.2 to 2mgL(-)(1) for UHPLC-PDA) and good precision parameters (RSD lower than 0.06%) were obtained. All methods were successfully applied to natural samples. LTQ-Orbitrap-MS allowed to identify other analytes of interest too. Good feasibility of the methods was also concluded from the analysis of catechin and quercetin release from new active packaging materials based on polypropylene added with catechins and green tea. Copyright © 2013 Elsevier Ltd. All rights reserved.

Determination of chloramphenicol and zeranols in pig muscle by immunoaffinity column clean-up and LC-MS/MS analysis.

PubMed

Wang, Qing; Zhao, Hua; Xi, Cunxian; Wang, Guomin; Chen, Dongdong; Ding, Shijia

2014-01-01

An immunoaffinity column clean-up and LC-MS/MS method was successfully developed for simultaneous determination of chloramphenicol, zearalanone, α-zearalanol, β-zearalanol, zearalenone, α-zearalenol and β-zearalenol in pig muscle. The sample was extracted with diethyl ether after enzymatic digestion by β-glucuronidase/sulfatase. The extracted solution was evaporated to dryness and the residue was then dissolved in 1 ml of 50% acetonitrile solution. After filtration and dilution with phosphate buffer solution (PBS), the reconstituted solution was cleaned-up with an IAC-CZ immunoaffinity column and then analysed by HPLC-MS/MS. The established method were validated by linearity (r ≥ 0.9990), precision (RSD ≥ 2.9%), average recovery (74.5-105.0%) and limit of detection (0.04-0.10 μg kg(-1)). The developed method is rapid, reliable, sensitive, accurate and has good applicability for real samples.

A novel pH optical sensor using methyl orange based on triacetylcellulose membranes as support.

PubMed

Hosseini, Mohammad; Heydari, Rouhollah; Alimoradi, Mohammad

2014-07-15

A novel pH optical sensor based on triacetylcellulose membrane as solid support was developed by using immobilization of methyl orange indicator. The prepared optical sensor was fixed into a flow cell for on-line pH monitoring. Variables affecting sensor performance, such as pH of dye bonding to triacetylcellulose membrane and dye concentration have been fully evaluated and optimized. The calibration curve showed good behavior and precision (RSD<0.4%) in the pH range of 4.0-12.0. No significant variation was observed on sensor response with increasing the ionic strength in the range of 0.0-0.5M of sodium chloride. Determination of pH by using the proposed optical sensor is on-line, quick, inexpensive, selective and sensitive in the pH range of 4.0-12.0. 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

Highly sensitive, reproducible and stable SERS substrate based on reduced graphene oxide/silver nanoparticles coated weighing paper

NASA Astrophysics Data System (ADS)

Xiao, Guina; Li, Yunxiang; Shi, Wangzhou; Shen, Leo; Chen, Qi; Huang, Lei

2017-05-01

Paper-based surface-enhanced Raman scattering (SERS) substrates receive a great deal of attention due to low cost and high flexibility. Herein, we developed an efficient SERS substrate by gravure printing of sulfonated reduced graphene-oxide (S-RGO) thin film and inkjet printing of silver nanoparticles (AgNPs) on weighing paper successively. Malachite green (MG) and rhodamine 6G (R6G) were chosen as probe molecules to evaluate the enhanced performance of the fabricated SERS-active substrates. It was found that the S-RGO/AgNPs composite structure possessed higher enhancement ability than the pure AgNPs. The Raman enhancement factor of S-RGO/AgNPs was calculated to be as large as 109. The minimum detection limit for MG and R6G was down to 10-7 M with good linear responses (R2 = 0.9996, 0.9983) range from 10-4 M to 10-7 M. In addition, the S-RGO/AgNPs exhibited good uniformity with a relative standard deviation (RSD) of 7.90% measured by 572 points, excellent reproducibility with RSD smaller than 3.36%, and long-term stability with RSD less than 7.19%.

[Study on TLC identification and UPLC determination method of atractylenolide in Atractylodes macrocephala].

PubMed

Zhao, Yu-Jiao; Xu, Wen-Hui; Shen, Xiao-Li; Tian, Jun-Sheng; Qin, Xue-Mei

2017-02-01

This research is to establish TLC and UPLC methods for simultaneous determination of 3 atractylenolides in Atractylodes macrocephala. Silica gel GF254 plate was used for identification of A. macrocephala, and UPLC-PDA gradient elution method was used to simultaneously determine atractylenolide Ⅰ, Ⅱ and Ⅲ. The Waters BEH C₁₈ column（2.1 mm×100 mm,1.7 μm）with acetonitrile-water as mobile phase and the wavelength of UV detector of 235 nm were performed. The quality control study showed that the characteristic for identification by TLC was distinct and highly specific. The method of content determination was in accordance with the regulations. The quantitative evaluation of atractylenolide Ⅰ,Ⅱ and Ⅲ was in good linear range（r>0.999 9）, and the average recovery was 93.48%（RSD 1.4%）,94.97%（RSD 1.6%）,92.71%（RSD 1.2%）,respectively. TLC identification was in good specificity and repeatability, and the UPLC-PDA method for the simultaneous determination of 3 atractylenolides was simple and reliable for the quality control of A.macrocephala. Copyright© by the Chinese Pharmaceutical Association.

Method development for the determination of fluorine in water samples via the molecular absorption of strontium monofluoride formed in an electrothermal atomizer

NASA Astrophysics Data System (ADS)

Ozbek, Nil; Akman, Suleyman

The presence of fluorine (F) was detected via the rotational molecular absorption line of diatomic strontium-monofluoride (SrF) generated in the gas phase at 651.187 nm using high-resolution continuum source electrothermal atomic absorption spectrometry. Upon the addition of excess strontium (Sr) as the nitrate, the fluorine in the sample was converted to SrF in the gas phase of a graphite furnace. The effects on the accuracy, precision and sensitivity of variables such as the SrF wavelength, graphite furnace program, amount of Sr, coating of the graphite tube and platform with Zr and Ir and the use of a modifier were investigated and optimized. It was determined that there was no need to use a modifier or to cover the platform/tubes with Zr or Ir. Fluorine concentrations in various water samples (certified waste water, tap water, drinking water and mineral water) were determined using 20 μg of Sr as the molecule-forming reagent and applying a maximum pyrolysis temperature of 800 °C and a molecule-forming temperature of 2200 °C with a heating rate of 2000 °C s- 1. Good linearity was maintained up to 0.1 μg of F. The accuracy and precision of the method were tested by analyzing certified reference wastewater. The results were in good agreement with certified values, and the precision was satisfactory (RSD < 10%). The limit of detection and the characteristic mass for the method were 0.36 ng and 0.55 ng, respectively. Finally, the fluorine concentrations in several drinking water and mineral water samples taken from the market were determined. The results were in good agreement with the values supplied by the producers. No significant differences were found between the results from the linear calibration and standard addition techniques. The method was determined to be simple, fast, accurate and sensitive.

Enantioselective piezoelectric quartz crystal sensor for d-methamphetamine based on a molecularly imprinted polymer.

PubMed

Arenas, Leveriza F; Ebarvia, Benilda S; Sevilla, Fortunato B

2010-08-01

A piezoelectric quartz crystal (PQC) sensor based on a molecularly imprinted polymer (MIP) has been developed for enantioselective and quantitative analysis of d-(+)-methamphetamine (d(+)-MA). The sensor was produced by bulk polymerization and the resulting MIP was then coated on the gold electrode of an AT-cut quartz crystal. Conditions such as volume of polymer coating, curing time, type of PQC, baseline solvent, pH, and buffer type were found to affect the sensor response and were therefore optimized. The PQC-MIP gave a stable response to different concentrations of d(+)-MA standard solutions (response time = 10 to 100 s) with good repeatability (RSD = 0.03 to 3.09%; n = 3), good reproducibility (RSD = 3.55%; n = 5), and good reversibility (RSD = 0.36%; n = 3). The linear range of the sensor covered five orders of magnitude of analyte concentration, ranging from 10(-5) to 10(-1) microg mL(-1), and the limit of detection was calculated as 11.9 pg d(+)-MA mL(-1) . The sensor had a highly enantioselective response to d(+)-MA compared with its response to l(-)-MA, racemic MA, and phentermine. The developed sensor was validated by applying it to human urine samples from drug-free individuals spiked with standard d(+)-MA and from a confirmed MA user. Use of the standard addition method (SAM) and samples spiked with d(+)-MA at levels ranging from 1 x 10(-3) to 1 x 10(-2) microg mL(-1) showed recovery was good (95.3 to 110.9%).

The metal-organic framework HKUST-1 as efficient sorbent in a vortex-assisted dispersive micro solid-phase extraction of parabens from environmental waters, cosmetic creams, and human urine.

PubMed

Rocío-Bautista, Priscilla; Martínez-Benito, Carla; Pino, Verónica; Pasán, Jorge; Ayala, Juan H; Ruiz-Pérez, Catalina; Afonso, Ana M

2015-07-01

Three metal-organic frameworks (MOFs), specifically HKUST-1, MOF-5, and MIL-53(Al), have been synthetized, characterized, studied and compared in a vortex-assisted dispersive micro-solid-phase extraction (VA-D-µ-SPE) procedure in combination with high-performance liquid chromatography (HPLC) with diode-array detection (DAD) for determining seven parabens in environmental waters (tap water, swimming pool water, and water coming from a spa pool), human urine (from two volunteers), and cosmetic creams (two commercial brands). Experimental parameters, such as nature and amount of MOF, sample volume, nature of elution solvent and its amount, vortex and centrifugation time, among others, were properly optimized. HKUST-1 was the most adequate MOF to work with. Detection limits for the overall method down to 0.1 μgL(-1) for butylparaben (BPB) and benzylparaben (BzPB) were obtained, with determination coefficients (R(2)) higher than 0.9966 for a range of 0.5-147 μgL(-1) (depending on the paraben), average relative recoveries (RR, in %) of 80.3% at the low spiked level (7 μgL(-1)), and relative standard deviation (RSD) values below 10% also at the low spiked level. The strength of the affinity between HKUST-1 and parabens was evaluated, and it ranged from 33.5% for isopropylparaben (iPPB) to 77.0% for isobutylparaben (iBPB). When analyzing complex environmental waters, RR values of 78%, inter-day precision values (as RSD) lower than 15%, and intra-day precision values lower than 7.8% were obtained, despite the observed matrix effect. When analyzing cosmetic creams, parabens were detected, with contents ranging from 0.14 ± 0.01 μgg(-1) for EPB in the healing cream analyzed to 1.12 ± 0.07 mgg(-1) for MPB in the mask cream analyzed, with precision values (RSD) lower than 12% and RR values from 63.7% for propylparaben (PPB) to 121% for iPPB. When analyzing human urine, no parabens were detected but the method could be performed with RSD values lower than 19%. These results show the adequateness of MOFs as sorbents in VA-D-µ-SPE procedures despite sample complexity. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

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.

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.

A preliminary study on identification of Thai rice samples by INAA and statistical analysis

NASA Astrophysics Data System (ADS)

Kongsri, S.; Kukusamude, C.

2017-09-01

This study aims to investigate the elemental compositions in 93 Thai rice samples using instrumental neutron activation analysis (INAA) and to identify rice according to their types and rice cultivars using statistical analysis. As, Mg, Cl, Al, Br, Mn, K, Rb and Zn in Thai jasmine rice and Sung Yod rice samples were successfully determined by INAA. The accuracy and precision of the INAA method were verified by SRM 1568a Rice Flour. All elements were found to be in a good agreement with the certified values. The precisions in term of %RSD were lower than 7%. The LODs were obtained in range of 0.01 to 29 mg kg-1. The concentration of 9 elements distributed in Thai rice samples was evaluated and used as chemical indicators to identify the type of rice samples. The result found that Mg, Cl, As, Br, Mn, K, Rb, and Zn concentrations in Thai jasmine rice samples are significantly different but there was no evidence that Al is significantly different from concentration in Sung Yod rice samples at 95% confidence interval. Our results may provide preliminary information for discrimination of rice samples and may be useful database of Thai rice.

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.

Bio-assay guided isolation of α-glucosidase inhibitory constituents from Hibiscus mutabilis leaves.

PubMed

Kumar, Deepak; Kumar, Hemanth; Vedasiromoni, J R; Pal, Bikas C

2012-01-01

The increasing demand for natural-product-based medicines and health-care products for the management of diabetes encouraged investigation of this commonly available Indian plant. To establish the anti-diabetic (α-glucosidase inhibitory) activity of H. mutabilis leaf extract, isolate and identify the constituents responsible for the activity, and validate a HPLC method for quantification of the active constituents for standardisation of the extract. The methanolic extract of leaves was partitioned between water, n-butanol and ethyl acetate. Bio-assay guided fractionation, based on inhibition of α-glucosidase, allowed isolation and identification of the active components. The active components were quantified using RP-HPLC-DAD validated for linearity, limit of detection, limit of quantification, precision, accuracy and robustness for this plant extract and the partitioned fractions. Ferulic acid and caffeic acid were identified as the α-glucosidase inhibitors present in H. mutabilis. They were partitioned into an ethyl acetate fraction. The HPLC-DAD calibration curve showed good linearity (r² > 0.99). For the recovery studies the %RSD was less than 2%. The interday and intraday variations were found to be less than 4% RSD for retention time and response. The identification of α-glucosidase inhibition activity in H. mutabilis supports further investigations into the possible use of the plant for the management of diabetes. The HPLC method validated for these extracts will be useful in future research with the plant. Copyright © 2011 John Wiley & Sons, Ltd.

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.

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.

High Performance Liquid Chromatography-Diode Array Detector Method for the Simultaneous Determination of Five Compounds in the Pulp and Seed of Sea Buckthorn

PubMed Central

Zhao, Lu; Wen, E; Upur, Halmuart; Tian, Shuge

2017-01-01

Context: Sea buckthorn (Hippophae rhamnoides L.) as a traditional Chinese medicinal plant has various uses in Xinjiang. Objective: A reversed-phase rapid-resolution liquid-chromatography method with diode array detector was developed for simultaneous determination of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the pulp and seed of sea buckthorn, a widely used traditional Chinese medicine for promoting metabolism and treating scurvy and other diseases. Settings and design: Compounds were separated on an Agilent ZORBAX SB-C18 column (4.6 mm × 250 mm, 5 μm; USA) with gradient elution using methanol and 0.4% phosphoric acid (v/v) at 1.0 mL/min. Detection wavelength was set at 280 nm. Materials and Methods: The fruits of wild sea buckthorn were collected from Wushi County in Aksu, Xinjiang Province. Statistical performances: The RSD of precision test of the five compounds were in the range of 0.60-2.22%, and the average recoveries ranged from 97.36% to 101.19%. Good linearity between specific chromatographic peak and component qualities were observed in the investigated ranges for all the analytes (R2 > 0.9997). Results: The proposed method was successfully applied to determine the levels of five active components in sea buckthorn samples from Aksu in Xinjiang. Conclusions: The proposed method is simple, fast, sensitive, accurate, and suitable for quantitative assessment of the pulp and seed of sea buckthorn. SUMMARY Quantitative analysis method of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the extract of sea buckthorn pulp and seed is developed by high-performance liquid chromatography (HPLC) diode array detection.This method is simple and accurate; has strong specificity, good precision, and high recovery rate; and provides a reliable basis for further development of the substances in the pulp and seed of sea buckthorn.The method is widely used for content determination of active ingredients or physiologically active components in traditional Chinese medicine and its preparation Abbreviation used: PR: protocatechuic acid, RU: rutin, QU: quercetin, KA: kaempferol, IS: isorhamnetin, HPLC: high-performance liquid chromatography, HPLC-DAD: high performance liquid chromatographydiode array detector, LOD: linearity and limit of detection, LOQ: limit of quantitation, RSD: relative standard deviation PMID:28216897

Magnetic solid phase extraction of typical polycyclic aromatic hydrocarbons from environmental water samples with metal organic framework MIL-101 (Cr) modified zero valent iron nano-particles.

PubMed

Zhou, Qingxiang; Lei, Man; Wu, Yalin; Yuan, Yongyong

2017-03-03

Metal-organic framework material has been paid more attention because of its good physical and chemical properties. Nanoscale zero valent iron is also in the center of concern recently. Combination of their merits will give impressive results. Present study firstly synthesized a new magnetic nanomaterial nano-scale zero valent iron-functionalized metal-organic framworks MIL-101 (Fe@MIL-101) by co-precipitation method. The morphology and structure of the as-prepared Fe@MIL-101 were characterized by transmission electron microscopy and X-ray diffraction, etc. The experimental results showed that Fe@MIL-101 earned good adsorption ability to polycyclic aromatic hydrocarbons. The limits of detection of developed magnetic solid phase extraction were all below 0.064μgL -1 and precision can be expressed as relative standard deviation (RSD, %) and which was better than 4.4% (n=6). The real water analysis indicated that the spiked recoveries were satisfied, and Fe@MIL-101 earned excellent reusability. All these demonstrated that Fe@MIL-101 exhibited excellent adsorption capability to polycyclic aromatic hydrocarbons and would be a good adsorbent for development of new monitoring methods for environmental pollutants. Copyright © 2017 Elsevier B.V. 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.

Spectrofluorimetric determination of some water-soluble vitamins.

PubMed

Mohamed, Abdel-Maaboud I; Mohamed, Horria A; Abdel-Latif, Niveen M; Mohamed, Marwa R

2011-01-01

Two simple and sensitive spectrofluorimetric methods were developed for determination of three water-soluble vitamins (B1, B2, and B6) in mixtures in the presence of cyanocobalamin. The first one was for thiamine determination, which depends on the oxidation of thiamine HCl to thiochrome by iodine in an alkaline medium. The method was applied accurately to determine thiamine in binary, ternary, and quaternary mixtures with pyridoxine HCl, riboflavin, and cyanocobalamin without interference. In the second method, riboflavin and pyridoxine HCl were determined fluorimetrically in acetate buffer, pH 6. The three water-soluble vitamins (B1, B2, and B6) were determined spectrofluorimetrically in binary, ternary, and quaternary mixtures in the presence of cyanocobalamin. All variables were studied in order to optimize the reaction conditions. Linear relationship was obeyed for all studied vitamins by the proposed methods at their corresponding lambda(exc) or lambda(em). The linear calibration curves were obtained from 10 to 500 ng/mL; the correlation ranged from 0.9991 to 0.9999. The suggested procedures were applied to the analysis of the investigated vitamins in their laboratory-prepared mixtures and pharmaceutical dosage forms from different manufacturers. The RSD range was 0.46-1.02%, which indicates good precision. No interference was observed from common pharmaceutical additives. Good recoveries (97.6 +/- 0.7-101.2 +/- 0.8%) were obtained. Statistical comparison of the results with reported methods shows excellent agreement and indicates no significant difference in accuracy and precision.

Validation of an analytical method for simultaneous high-precision measurements of greenhouse gas emissions from wastewater treatment plants using a gas chromatography-barrier discharge detector system.

PubMed

Pascale, Raffaella; Caivano, Marianna; Buchicchio, Alessandro; Mancini, Ignazio M; Bianco, Giuliana; Caniani, Donatella

2017-01-13

Wastewater treatment plants (WWTPs) emit CO 2 and N 2 O, which may lead to climate change and global warming. Over the last few years, awareness of greenhouse gas (GHG) emissions from WWTPs has increased. Moreover, the development of valid, reliable, and high-throughput analytical methods for simultaneous gas analysis is an essential requirement for environmental applications. In the present study, an analytical method based on a gas chromatograph (GC) equipped with a barrier ionization discharge (BID) detector was developed for the first time. This new method simultaneously analyses CO 2 and N 2 O and has a precision, measured in terms of relative standard of variation RSD%, equal to or less than 6.6% and 5.1%, respectively. The method's detection limits are 5.3ppm v for CO 2 and 62.0ppb v for N 2 O. The method's selectivity, linearity, accuracy, repeatability, intermediate precision, limit of detection and limit of quantification were good at trace concentration levels. After validation, the method was applied to a real case of N 2 O and CO 2 emissions from a WWTP, confirming its suitability as a standard procedure for simultaneous GHG analysis in environmental samples containing CO 2 levels less than 12,000mg/L. Copyright © 2016 Elsevier B.V. All rights reserved.

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.

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

Simultaneous Determination of Soyasaponins and Isoflavones in Soy (Glycine max L.) Products by HPTLC-densitometry-Multiple Detection.

PubMed

Shawky, Eman; Sallam, Shaimaa M

2017-11-01

A new high-throughput method was developed for the simultaneous analysis of isoflavones and soyasaponnins in Soy (Glycine max L.) products by high-performance thin-layer chromatography with densitometry and multiple detection. Silica gel was used as the stationary phase and ethyl acetate:methanol:water:acetic acid (100:20:16:1, v/v/v/v) as the mobile phase. After chromatographic development, multi-wavelength scanning was carried out by: (i) UV-absorbance measurement at 265 nm for genistin, daidzin and glycitin, (ii) Vis-absorbance measurement at 650 nm for Soyasaponins I and III, after post-chromatographic derivatization with anisaldehyde/sulfuric acid reagent. Validation of the developed method was found to meet the acceptance criteria delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. Calibrations were linear with correlation coefficients of >0.994. Intra-day precisions relative standard deviation (RSD)% of all substances in matrix were determined to be between 0.7 and 0.9%, while inter-day precisions (RSD%) ranged between 1.2 and 1.8%. The validated method was successfully applied for determination of the studied analytes in soy-based infant formula and soybean products. The new method compares favorably to other reported methods in being as accurate and precise and in the same time more feasible and cost-effective. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Development of Silicalite/Glucose Oxidase-Based Biosensor and Its Application for Glucose Determination in Juices and Nectars

NASA Astrophysics Data System (ADS)

Dudchenko, Oleksandr Ye; Pyeshkova, Viktoriya M.; Soldatkin, Oleksandr O.; Akata, Burcu; Kasap, Berna O.; Soldatkin, Alexey P.; Dzyadevych, Sergei V.

2016-02-01

The application of silicalite for improvement of enzyme adsorption on new stainless steel electrodes is reported. Glucose oxidase (GOx) was immobilized by two methods: cross-linking by glutaraldehyde (GOx-GA) and cross-linking by glutaraldehyde along with GOx adsorption on silicalite-modified electrode (SME) (GOx-SME-GA). The GOx-SME-GA biosensors were characterized by a four- to fivefold higher sensitivity than GOx-GA biosensor. It was concluded that silicalite together with GA sufficiently enhances enzyme adhesion on stainless steel electrodes. The developed GOx-SME-GA biosensors were characterized by good reproducibility of biosensor preparation (relative standard deviation (RSD)—18 %), improved signal reproducibility (RSD of glucose determination was 7 %), and good storage stability (29 % loss of activity after 18-day storage). A series of fruit juices and nectars was analyzed using GOx-SME-GA biosensor for determination of glucose concentration. The obtained results showed good correlation with the data of high-performance liquid chromatography (HPLC) ( R = 0.99).

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.

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.

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

Shekhar, R.; Karunasagar, D.; Ranjit, M.

An open-to-air type electrolyte cathode discharge (ELCAD) has been developed with a new design. The present configuration leads to a stable plasma even at low flow rates (0.96 mL/min). Plasma fluctuations arising from the variations in the gap between solid anode and liquid cathode were eliminated by providing a V-groove to the liquid glass-capillary. Cathode (ground) connection is given to the solution at the V-groove itself. Interfaced to atomic emission spectrometry (AES), its analytical performance is evaluated. The optimized molarity of the solution is 0.2 M. The analytical response curves for Ca, Cu, Cd, Pb, Hg, Fe, and Zn demonstratedmore » good linearity. The limit of detections of Ca, Cu, Cd, Pb, Hg, Fe, and Zn are determined to be 17, 11, 5, 45, 15, 28, and 3 ng mL{sup -1}. At an integration time of 0.3 s, the relative standard deviation (RSD) values of the acid blank solutions are found to be less than 10% for the elements Ca, Cu, Cd, Hg, Fe, and Zn and 18% for Pb. The method is applied for the determination of the elemental constituents in different matrix materials such as tuna fish (IAEA-350), oyster tissue (NIST SRM 1566a), and coal fly ash (CFA SRM 1633b). The obtained results are in good agreement with the certified values. The accuracy is found to be between 7% and 0.6% for major to trace levels of constituent elements and the precision between 11% and 0.6%. For the injection of 100 {mu} L of 200 ng mL{sup -1} mercury solution at the flow rate of 0.8 mL/min, the flow injection studies resulted in the relative standard deviation (RSD) of 8%, concentration detection limit of 10 ng/mL, and mass detection limit of 1 ng for mercury.« less

[Construction and characterization of a selective membrane electrode for tenoxicam determination].

PubMed

Murăraşu, Andreea Elena; Mândrescu, Mariana; Spac, A F; Dorneanu, V

2010-01-01

This paper describes the construction and characterization of a selective membrane electrode which can be used for determination of tenoxicam. The electroactive compound is a precipitate obtained in 2 N hydrocloric acid solution containing tenoxicam in which a solution of iodine is added. The membrane is made by mixing the electroactive compound with polyethylene using tetrahydrofurane as solvent. The solution is evaporated in order to obtain a thick membrane, which is attached at one end of a PVC tube and is fixed with the same polymeric solution. In this tube an internal Ag/AgCl reference electrode is inserted. The assembly is filled with an internal solution containing tenoxicam. The electrode was characterized (electrode slope, selectivity, optimal pH range, response time, life time). The developed method was validated. The method showed a good liniarity in the range of 10(-6)-10(-1) M (the correlation coefficient r = 0.9999). The detection limit (LD) was 7.347 x 10(-7) M and the quantification limit (LQ) was 1.017 x 10(-6) M. There were established the precision (RSD = 1.79%) and the accuracy (mean recovery is 100.17%) The experimental results demonstrated a good sensibility.

Accurate determination of residual acrylic acid in superabsorbent polymer of hygiene products by headspace gas chromatography.

PubMed

Zhang, Shu-Xin; Chai, Xin-Sheng; Jiang, Ran

2017-02-17

This work reports on a method for the determination of residual acrylic acid (AA) in the superabsorbent polymers for hygiene products by headspace analysis. It was based on water extraction for the polymer sample at a room temperature for 50min. Then, the AA in the extractant reacted with bicarbonate solution in a closed headspace sample vial, from which the carbon dioxide generated from the reaction (within 20min at 70°C) was detected by gas chromatography (GC). It was found that there is adsorption partition equilibrium of AA between solid-liquid phases. Therefore, an equation for calculating the total AA content in the original polymers sample was derived based on the above phase equilibrium. The results show that the HS-GC method has good precision (RSD<2.51%) and good accuracy (recoveries from 93 to 105%); the limit of quantification (LOQ) was 373mg/kg. The present method is rapid, accurate, and suitable for determining total residual acrylic acid in a wide variety of applications from processing of superabsorbent polymer to commercial products quality control. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of the solubility of low volatility liquid organic compounds in water using volatile-tracer assisted headspace gas chromatography.

PubMed

Zhang, Shu-Xin; Chai, Xin-Sheng; Barnes, Donald G

2016-02-26

This study reports a new headspace gas chromatographic method (HS-GC) for the determination of water solubility of low volatility liquid organic compounds (LVLOs). The HS-GC analysis was performed on a set of aqueous solutions containing a range of concentrations of toluene-spiked (as a tracer) LVLOs, from under-saturation to over-saturation. A plot of the toluene tracer GC signal vs. the concentration of the LVLO results in two lines of different slopes that intersect at the concentration corresponding to the compound's solubility in water. The results showed that the HS-GC method has good precision (RSD <6.3%) and good accuracy, in which the relative deference between the data measured by the HS-GC method and the reference method were within 6.0%. The HS-GC method is simple and particularly suitable for measuring the solubility of LVLOs at elevated temperatures. This approach should be of special interest to those concerned about the impact of the presence of low-volatility organic liquids in waters of environmental and biological systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous determination of cyanogen chloride and cyanogen bromide in treated water at sub-microg/L levels by a new solid-phase microextraction-gas chromatographic-electron-capture detection method.

PubMed

Cancho, B; Ventur, F; Galceran, M

2000-11-03

A headspace solid-phase microextraction (HS-SPME) procedure has been developed and applied for the determination of cyanogen halides in treated water samples at microg/L concentrations. Several SPME coatings were tested, the divinylbenzene-Carboxen-polydimethylsiloxane fiber being the most appropriate coating. GC-electron-capture detection was used for separation and quantitation. Experimental parameters such as sample volume, addition of a salt, extraction time and desorption conditions were studied. The optimized method has an acceptable linearity, good precision, with RSD values <10% for both compounds, and it is sufficiently sensitive to detect ng/L levels. HS-SPME was compared with liquid-liquid microextraction (US Environmental Protection Agency Method 551.1) for the analysis of spiked ultrapure and granular activated carbon filtered water samples. There was good agreement between the results from both methods. Finally, the optimized procedure was applied to determine both compounds at the Barcelona water treatment plant (N.E. Spain). Cyanogen chloride in treated water was <1.0 microg/L and cyanogen bromide ranged from 3.2 to 6.4 microg/L.

Method development and qualification of capillary zone electrophoresis for investigation of therapeutic monoclonal antibody quality.

PubMed

Suba, Dávid; Urbányi, Zoltán; Salgó, András

2016-10-01

Capillary electrophoresis techniques are widely used in the analytical biotechnology. Different electrophoretic techniques are very adequate tools to monitor size-and charge heterogenities of protein drugs. Method descriptions and development studies of capillary zone electrophoresis (CZE) have been described in literature. Most of them are performed based on the classical one-factor-at-time (OFAT) approach. In this study a very simple method development approach is described for capillary zone electrophoresis: a "two-phase-four-step" approach is introduced which allows a rapid, iterative method development process and can be a good platform for CZE method. In every step the current analytical target profile and an appropriate control strategy were established to monitor the current stage of development. A very good platform was established to investigate intact and digested protein samples. Commercially available monoclonal antibody was chosen as model protein for the method development study. The CZE method was qualificated after the development process and the results were presented. The analytical system stability was represented by the calculated RSD% value of area percentage and migration time of the selected peaks (<0.8% and <5%) during the intermediate precision investigation. Copyright © 2016 Elsevier B.V. All rights reserved.

[Determination of four alkaloids in Corydalis decumbens by HPLC].

PubMed

Shen, Yan; Han, Chao; Xia, Biqi; Zhou, Yongfang; Liu, Cuiping; Liu, Aili

2011-08-01

To establish a quantitative HPLC method for determination of protopine, palmatine hydrochloride, bicuculline and tetrahydropalmatine, in Corydalis decumbens. The separation was performed on a ZORBAX Eclipse XDB-C18 column (4.6 mm x 150 mm, 5 microm) at a flow rate of 1.0 mL x min(-1) using mixtures of two solvents [A(20 mmol x L(-1) ammonium acetate)-B(acetonitrile)]: with a gradient elution. The column oven temperature was 30 degrees C and the detection wavelength was set at 280 nm. The 4 alkaloids were well separated by this HPLC method. Linearifies of protopine, palmatine hydrochloride, bicuculline and tetrahydropalmatine were good in the ranges of 1.44-46.0 (r = 0.999 4), 1.2640.2 (r = 0.999 8), 1.37-44.0 (r = 0.999 9), and 1.3643.6 mg x L(-1) (r = 0.999 9), respectively. The average recoveries were 98.2% with RSD 2.7% for protopine, 101.9% with RSD 2.5% for palmatine hydrochloride, 102.8% with RSD 3.5% for tetrahydropalmatine, and 98.8% with RSD 3.1% for tetrahydropalmatine. This method is proved to be convenient, reliable and accurate., and it can be used for quality control of C. decumbens.

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.

Development and validation of a UV-spectrophotometric method for the determination of pheniramine maleate and its stability studies

NASA Astrophysics Data System (ADS)

Raghu, M. S.; Basavaiah, K.; Ramesh, P. J.; Abdulrahman, Sameer A. M.; Vinay, K. B.

2012-03-01

A sensitive, precise, and cost-effective UV-spectrophotometric method is described for the determination of pheniramine maleate (PAM) in bulk drug and tablets. The method is based on the measurement of absorbance of a PAM solution in 0.1 N HCl at 264 nm. As per the International Conference on Harmonization (ICH) guidelines, the method was validated for linearity, accuracy, precision, limits of detection (LOD) and quantification (LOQ), and robustness and ruggedness. A linear relationship between absorbance and concentration of PAM in the range of 2-40 μg/ml with a correlation coefficient (r) of 0.9998 was obtained. The LOD and LOQ values were found to be 0.18 and 0.39 μg/ml PAM, respectively. The precision of the method was satisfactory: the value of relative standard deviation (RSD) did not exceed 3.47%. The proposed method was applied successfully to the determination of PAM in tablets with good accuracy and precision. Percentages of the label claims ranged from 101.8 to 102.01% with the standard deviation (SD) from 0.64 to 0.72%. The accuracy of the method was further ascertained by recovery studies via a standard addition procedure. In addition, the forced degradation of PAM was conducted in accordance with the ICH guidelines. Acidic and basic hydrolysis, thermal stress, peroxide, and photolytic degradation were used to assess the stability-indicating power of the method. A substantial degradation was observed during oxidative and alkaline degradations. No degradation was observed under other stress conditions.

An electrochemical sensor prepared by sonochemical one-pot synthesis of multi-walled carbon nanotube-supported cobalt nanoparticles for the simultaneous determination of paracetamol and dopamine.

PubMed

Kutluay, Aysegul; Aslanoglu, Mehmet

2014-08-11

Multi-walled carbon nanotubes (MWCNTs) functionalized by cobalt nanoparticles were obtained using a single step chemical deposition method in an ultrasonic bath. The composite material was characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The electroactivity of the cobalt-functionalized MWCNTs was assessed in respect to the electrooxidation of paracetamol (PAR) and dopamine (DA). It was found that the carbon nanotube supported cobalt nanoparticles have significantly higher catalytic properties. The proposed electrode has been applied for the simultaneous determination of PAR and DA. The modified electrode could resolve the overlapped voltammetric waves of PAR and DA into two well-defined voltammetric peaks with peak to peak separation of about 203 mV. On the other hand, the presence of potential drug interfering compounds AA and UA did not affect the voltammetric responses of PAR and DA. The current of oxidation peaks showed a linear dependent on the concentrations of PAR and DA in the range of 5.2×10(-9)-4.5×10(-7) M (R(2)=0.9987) and 5.0×10(-8)-3.0×10(-6) M (R(2)=0.9999), respectively. The detection limits of 1.0×10(-9) M and 1.5×10(-8) M were obtained for PAR and DA, respectively. The proposed electrode showed good stability (peak current change: 4.9% with and RSD of 2.6% for PAR; 5.5% with and RSD of 3.0% for DA over 3 weeks), reproducibility (RSD 2.3% for PAR and RSD 1.5% for DA), repeatability (RSD 2.25% for PAR and RSD 2.50% for DA) and high recovery (99.7% with an RSD of 1.3% for PAR; 100.8% with an RSD of 1.8% for DA). The proposed method was successfully applied to the determination of PAR and DA in pharmaceuticals. Copyright © 2014. Published by Elsevier B.V.

Quantitative Detection of Trace Malachite Green in Aquiculture Water Samples by Extractive Electrospray Ionization Mass Spectrometry

PubMed Central

Fang, Xiaowei; Yang, Shuiping; Chingin, Konstantin; Zhu, Liang; Zhang, Xinglei; Zhou, Zhiquan; Zhao, Zhanfeng

2016-01-01

Exposure to malachite green (MG) may pose great health risks to humans; thus, it is of prime importance to develop fast and robust methods to quantitatively screen the presence of malachite green in water. Herein the application of extractive electrospray ionization mass spectrometry (EESI-MS) has been extended to the trace detection of MG within lake water and aquiculture water, due to the intensive use of MG as a biocide in fisheries. This method has the advantage of obviating offline liquid-liquid extraction or tedious matrix separation prior to the measurement of malachite green in native aqueous medium. The experimental results indicate that the extrapolated detection limit for MG was ~3.8 μg·L−1 (S/N = 3) in lake water samples and ~0.5 μg·L−1 in ultrapure water under optimized experimental conditions. The signal intensity of MG showed good linearity over the concentration range of 10–1000 μg·L−1. Measurement of practical water samples fortified with MG at 0.01, 0.1 and 1.0 mg·L−1 gave a good validation of the established calibration curve. The average recoveries and relative standard deviation (RSD) of malachite green in lake water and Carassius carassius fish farm effluent water were 115% (6.64% RSD), 85.4% (9.17% RSD) and 96.0% (7.44% RSD), respectively. Overall, the established EESI-MS/MS method has been demonstrated suitable for sensitive and rapid (<2 min per sample) quantitative detection of malachite green in various aqueous media, indicating its potential for online real-time monitoring of real life samples. PMID:27529262

Quantitative Detection of Trace Malachite Green in Aquiculture Water Samples by Extractive Electrospray Ionization Mass Spectrometry.

PubMed

Fang, Xiaowei; Yang, Shuiping; Chingin, Konstantin; Zhu, Liang; Zhang, Xinglei; Zhou, Zhiquan; Zhao, Zhanfeng

2016-08-11

Exposure to malachite green (MG) may pose great health risks to humans; thus, it is of prime importance to develop fast and robust methods to quantitatively screen the presence of malachite green in water. Herein the application of extractive electrospray ionization mass spectrometry (EESI-MS) has been extended to the trace detection of MG within lake water and aquiculture water, due to the intensive use of MG as a biocide in fisheries. This method has the advantage of obviating offline liquid-liquid extraction or tedious matrix separation prior to the measurement of malachite green in native aqueous medium. The experimental results indicate that the extrapolated detection limit for MG was ~3.8 μg·L(-1) (S/N = 3) in lake water samples and ~0.5 μg·L(-1) in ultrapure water under optimized experimental conditions. The signal intensity of MG showed good linearity over the concentration range of 10-1000 μg·L(-1). Measurement of practical water samples fortified with MG at 0.01, 0.1 and 1.0 mg·L(-1) gave a good validation of the established calibration curve. The average recoveries and relative standard deviation (RSD) of malachite green in lake water and Carassius carassius fish farm effluent water were 115% (6.64% RSD), 85.4% (9.17% RSD) and 96.0% (7.44% RSD), respectively. Overall, the established EESI-MS/MS method has been demonstrated suitable for sensitive and rapid (<2 min per sample) quantitative detection of malachite green in various aqueous media, indicating its potential for online real-time monitoring of real life samples.

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.

System for quantifying the formation stages of corneal arcus

NASA Astrophysics Data System (ADS)

Nasution, Aulia; Fahdarina, Sally; Cahya, Deny I.

2015-07-01

Extensive research on interpreting the clinical signs of corneal-arcus formation and their related diagnostics potentials have found that there is a strong correlation of the arcus formation with the risk of coronary artery diseases and lipid stratification. Clinically the stages of the arcus formation are normally observed as separate grey-whitish arcs, that are formed at the inferior and then at the superior poles of the cornea. These arcs will by time being elongated to form a ring approximately 1 mm in width. In this paper, efforts to develop quantification system that is capable to recognize the stages of the arcus formation will be reported. The quantification was based on eye-images taken using prior developed low-cost digital image acquisition system, which self constructed from a plastic safety welding-goggle that was modified by placing two Logitec C525 webcam and LEDs lighting system. Pattern images of arcs with variation of arc's positions, lengths and thickness were used for pre-calibration purposes. Then these similar arcs are drawn on the of periphery of cornea images to simulate dummy corneal arcus, which mimick the stages of corneal arcus development. Using 672 data images, results of recognition show a good recognition rate, i.e. 93.6 % for determining arc's length (with maximum %RSD of 5.67 %) and 84.83 % for determining arc's thickness (with maximum %RSD of 5.67 %). Worser precision data were observed to happen for the small arc's length as well as small arc's thickness. Current efforts are devoted to translate the system for clinical trials.

Development of Simultaneous Analysis of Thirteen Bioactive Compounds in So-Cheong-Ryong-Tang Using UPLC-DAD

PubMed Central

2018-01-01

So-Cheong-Ryong-Tang, which is a standardized Korean medicine of the National Health Insurance, is a traditional prescription for the treatment of allergic rhinitis, bronchitis, and bronchial asthma. Simultaneous analysis and development of SCRT is essential for its stability, efficacy, and risk management. In this study, a simple, reliable, and accurate method using ultrahigh-performance liquid chromatography (UPLC) fingerprinting with a diode array detector (DAD) was developed for the simultaneous analysis. The chromatographic separation of the analytes was performed by an ACQUITY UPLC BEH C18 column (1.7 μM, 2.1 × 100 mm, Waters) with a mobile phase of water containing 0.01% (v/v) phosphoric acid and acetonitrile containing 0.01% (v/v) phosphoric acid. The flow rate and detection wavelength were set at 0.4 mL/min and 215, 230, 254, and 280 nm. All calibration curves of the thirteen components showed good linearity (R2 > 0.999). The limit of detection and limit of quantification ranged 0.001–0.360 and 0.004–1.200 µg/mL, respectively. The relative standard deviation (RSD) of intra- and interday was less than 2.60%, and the recoveries were within the range 76.08–103.79% with an RSD value of 0.03–1.50%. The results showed that the developed method was simple, reliable, accurate, sensitive, and precise for the quantification of bioactive components of SCRT. PMID:29854559

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.

Determination of the Marker Diarylheptanoid Phytoestrogens in Curcuma comosa Rhizomes and Selected Herbal Medicinal Products by HPLC-DAD.

PubMed

Yingngam, Bancha; Brantner, Adelheid; Jinarat, Damrongsak; Kaewamatawong, Rawiwun; Rungseevijitprapa, Wandee; Suksamrarn, Apichart; Piyachaturawat, Pawinee; Chokchaisiri, Ratchanaporn

2018-01-01

A method for quantification of diarylheptanoids in Curcuma comosa rhizomes and selected pharmaceutical preparations was established by using HPLC-diode array detector (DAD). The chromatographic separation of three diarylheptanoids [(3S)-1-(3,4-dihydroxy-phenyl)-7-phenyl-(6E)-6-hepten-3-ol (1), (3R)-1,7-diphenyl-(4E,6E)-4,6-heptadien-3-ol (2), and (3S)-1,7-diphenyl-(6E)-6-hepten-3-ol (3)] was performed on a Luna C 18 analytical column using gradient elution with 0.5% acetic acid in water and acetonitrile with a flow rate of 1 mL/min and a column temperature of 35°C. The calibration curves for the analytes showed good linearity (R 2 >0.999), high precision (relative standard deviation (RSD) <2%) and acceptable recovery (98.35-103.90%, RSD <2%). The limit of detection (LOD) and limit of quantification (LOQ) were 0.06-0.22 and 0.18-0.69 µg/mL, respectively. The results of all validated parameters were within the limits according to the International Conference on Harmonization (ICH) Guidelines. The established method was successfully applied for qualitative and quantitative determination of the three constituents in different samples of C. comosa and some commercial products in capsules. The simplicity, rapidity, and reliability of the method could be useful for the fingerprint analysis and standardization of diarylheptanoids, which are responsible for the estrogenic activity in raw materials and herbal medicinal products of C. comosa.

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).

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.

Determination of vigabatrin in human plasma and urine by high-performance liquid chromatography with UV-Vis detection.

PubMed

Cetin, Sevil Müge; Atmaca, Sedef

2004-03-26

A simple and reliable high-performance liquid chromatographic (HPLC) method with UV-Vis detection has been developed and validated for the determination of vigabatrin (VG) in human plasma and urine. The samples were pre-column derivatizated with 1,2-naphthoquinone-4-sulphonic acid sodium salt (NQS). A good chromatographic separation was achieved on a C18 column with a mobile phase consisting of acetonitrile and 10 mM orthophosphoric acid (pH 2.5) gradient elution. Tranexamic acid was used as an internal standard (I.S.). The method was linear over the concentration range of 0.8-30.0 microg/ml for both samples. The method is precise (relative standard deviation (R.S.D.) <9.13%) and accurate (relative mean error (RME) <-8.75%); analytical recoveries were 81.07% for plasma and 83.05% for urine. The assay was applied to pharmacokinetic study in a healthy volunteer after a single oral administration of 1 g of vigabatrin.

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.

Qualitative and Quantitative Analysis of Volatile Components of Zhengtian Pills Using Gas Chromatography Mass Spectrometry and Ultra-High Performance Liquid Chromatography.

PubMed

Liu, Cui-Ting; Zhang, Min; Yan, Ping; Liu, Hai-Chan; Liu, Xing-Yun; Zhan, Ruo-Ting

2016-01-01

Zhengtian pills (ZTPs) are traditional Chinese medicine (TCM) which have been commonly used to treat headaches. Volatile components of ZTPs extracted by ethyl acetate with an ultrasonic method were analyzed by gas chromatography mass spectrometry (GC-MS). Twenty-two components were identified, accounting for 78.884% of the total components of volatile oil. The three main volatile components including protocatechuic acid, ferulic acid, and ligustilide were simultaneously determined using ultra-high performance liquid chromatography coupled with diode array detection (UHPLC-DAD). Baseline separation was achieved on an XB-C18 column with linear gradient elution of methanol-0.2% acetic acid aqueous solution. The UHPLC-DAD method provided good linearity (R (2) ≥ 0.9992), precision (RSD < 3%), accuracy (100.68-102.69%), and robustness. The UHPLC-DAD/GC-MS method was successfully utilized to analyze volatile components, protocatechuic acid, ferulic acid, and ligustilide, in 13 batches of ZTPs, which is suitable for discrimination and quality assessment of ZTPs.

A "Dual-acceptor Channel" Membraneless Gas-diffusion Unit for Simultaneous Determination of Ethanol and Acetaldehyde in Liquors Using Reverse Flow Injection.

PubMed

Choengchan, Nathawut; Poontong, Bangerdsuk; Mathaweesansurn, Arjnarong; Maneerat, Noppadol; Motomizu, Shoji; Ratanawimarnwong, Nuanlaor; Nacapricha, Duangjai

2018-01-01

A new design of membraneless gas-diffusion unit with dual acceptor channels for separation, collection and simultaneous determination of two volatile analytes in liquid sample is presented. The unit is comprised of three parallel channels in a closed module. A sample is aspirated into the central channel and two kinds of reagents are introduced into the other two channels. Two analytes are isolated from the sample matrix by diffusion into head-space and absorbed into the specific reagents. Non-absorbed vapor is released by opening the programmable controlled lid. The unit was applied to liquors for measurement of ethanol and acetaldehyde using reverse flow injection. Dichromate and nitroprusside were exploited as reagents for colorimetric detection of ethanol and acetaldehyde, respectively. Good linearity ranges (r 2 >0.99) with high precision (RSD <2%) and high accuracy (recovery: 90 - 105%) were achieved. The results were compared to the results by GC-FID and no significant difference was observed by paired t-test (95% confidence).

Determination of epichlorohydrin and 1,3-dichloro-2-propanol in synthesis of cationic etherifying reagent by headspace gas chromatography.

PubMed

Tao, Zheng-Yi; Chai, Xin-Sheng; Wu, Shu-Bin

2011-09-16

This study demonstrates a headspace gas chromatographic(HS-GC) technique for the determination of residual epichlorohydrin (ECH) and generated 1,3-dichloro-2-propanol (DCP) in synthesis process of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHTAC). By a weight-based sampling method, coupled with significant dilution in 15.8% sodium sulfate and 0.1% silver nitrate mixed solution rapidly, the sample for HS-GC analysis is prepared. Based on the reaction stoichiometry, the conversion (R) of CHTAC during the synthesis process can be calculated from sampling weight and GC peak area. The results showed that the method has a good measurement precision (RSD<2.5%) and accuracy (recovery=101-104%) for the quantification of both ECH and DCP in the process samples. The present method is simple and accurate, which can be used for the efficient determination of the CHTAC conversion in the synthesis research. Copyright © 2011 Elsevier B.V. All rights reserved.

Preparation of Multiwalled Carbon Nanotubes/Hydroxyl-Terminated Silicone Oil Fiber and Its Application to Analysis of Crude Oils

PubMed Central

Tong, Ting; Zhang, Wanfeng; Dai, Wei; He, Sheng; Chang, Zhenyang; Gao, Xuanbo

2014-01-01

A simple and efficient method to analyze the volatile and semivolatile organic compounds in crude oils has been developed based on direct immersion solid-phase microextraction coupled to comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (DI-SPME-GC × GC/TOFMS). A novel fiber, multiwalled carbon nanotubes/hydroxyl-terminated silicone oil (MWNTs-TSO-OH), was prepared by sol-gel technology. Using standard solutions, the extraction conditions were optimized such as extraction mode, extraction temperature, extraction time, and salts effect. With the optimized conditions, a real crude oil sample was extracted and then analyzed in detail. It shows that the proposed method is very effective in simultaneously analyzing the normal and branched alkanes, cycloalkanes, aromatic hydrocarbons, and biomarkers of crude oil such as steranes and terpanes. Furthermore, the method showed good linearity (r > 0.999), precision (RSD < 8%), and detection limits ranging from 0.2 to 1.6 ng/L. PMID:24578659

Determination of total acid content in biomass hydrolysates by solvent-assisted and reaction based headspace gas chromatography.

PubMed

Huang, Liu-Lian; Hu, Hui-Chao; Chen, Li-Hui

2015-11-27

This work reports on a novel method for the determination of total acid (TA) in biomass hydrolysates by a solvent-assisted and reaction-based headspace gas chromatography (HS-GC). The neutralization reaction between the acids in hydrolysates and bicarbonate in an ethanol (50%) aqueous solution was performed in a closed headspace sample vial, from which the carbon dioxide generated from the reaction was detected by HS-GC. It was found that the addition of ethanol can effectively eliminate the precipitation of some organic acids in the biomass hydrolysates. The results showed that the reaction and headspace equilibration can be achieved within 45min at 70°C; the method has a good precision (RSD<3.27%) and accuracy (recovery of 97.4-105%); the limit of quantification is 1.36μmol. The present method is quite suitable to batch analysis of TA content in hydrolysate for the biorefinery related research. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of chlorinated volatile organic compounds in polyamine epichlorohydrin solution by headspace gas chromatography.

PubMed

Yan, Ning; Wan, Xiao-Fang; Chai, Xin-Sheng; Chen, Run-Quan

2017-05-05

This study demonstrated a headspace gas chromatographic (HS-GC) method for the determination of residual epichlorohydrin (ECH) and the by-product 1,3-dichloro-2-propanol (DCP) in polyamine epichlorohydrin (PAE) solution. It was based on the vapor-liquid phase equilibrium of these analytes at 60°C for 30min in a closed headspace sample vial before GC measurement. It was found that matrix of the PAE solution had the effect on the headspace equilibrium of these species and therefore a standard addition must be applied in the method validation. The results showed that the present method has a good measurement precision (RSD <2.90%) and accuracy (recoveries from 93.6 to 105%), and the limit of quantitation (LOQ) is 3.75mg/L for ECH and 0.8g/L for DCP. The present method is suitable to be used for analyzing the chlorinated volatile organic compounds in the commercial PAE resin solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

Rapid method for determination of carbonyl groups in lignin compounds by headspace gas chromatography.

PubMed

Li, Jing; Hu, Hui-Chao; Chai, Xin-Sheng

2015-07-24

The paper reports on a novel method for rapid determination of carbonyl in lignins by headspace gas chromatography (HS-GC). The method involves the quantitative carbonyl reduction for aldehydes in 2min at room temperature or for acetones in 30min at 80°C by sodium borohydride solution in a closed headspace sample vial. After the reaction, the solution was acidified by injecting sulfuric acid solution and the hydrogen released to the headspace was determined by GC using thermal-conductivity detector. The results showed that with the addition of SiO2 powder, the reduction reaction of carbonyl groups can be greatly facilitated. The method has a good measurement precision (RSD<7.74%) and accuracy (relative error <10% compared with a reference method) in the carbonyl quantification. It is suitable to be used for rapid determination of carbonyl content in lignin and related materials. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel multiple headspace extraction gas chromatographic method for measuring the diffusion coefficient of methanol in water and in olive oil.

PubMed

Zhang, Chun-Yun; Chai, Xin-Sheng

2015-03-13

A novel method for the determination of the diffusion coefficient (D) of methanol in water and olive oil has been developed. Based on multiple headspace extraction gas chromatography (MHE-GC), the methanol released from the liquid sample of interest in a closed sample vial was determined in a stepwise fashion. A theoretical model was derived to establish the relationship between the diffusion coefficient and the GC signals from MHE-GC measurements. The results showed that the present method has an excellent precision (RSD<1%) in the linear fitting procedure and good accuracy for the diffusion coefficients of methanol in both water and olive oil, when compared with data reported in the literature. The present method is simple and practical and can be a valuable tool for the determination of the diffusion coefficient of volatile analyte(s) into food simulants from food and beverage packaging material, both in research studies and in actual applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid and simple determination of selenium in blood serum by inductively coupled plasma-mass spectrometry (ICP-MS).

PubMed

Labat, L; Dehon, B; Lhermitte, M

2003-05-01

An inductively coupled plasma mass spectrometer (ICP-MS) with a rapid sample-preparative procedure was used for the determination of selenium in blood serum. Blood serum was prepared by dilution in an acidic solution consisting of nitric acid (1%), X-triton (0.1%) and 1-butanol (0.8%). A calibration curve was established for 1-40 microg mL(-1) (r(2)>0.99). The limit of detection was 0.5 microg mL(-1). Repeatability and intermediate precision were satisfactory with relative standard deviations (RSD) of 2.0% and 3.2%, respectively. This method was easily applied to reference materials with satisfactory accuracy. Good correlation (r(2)=0.96) was observed between ICP-MS and atomic absorption spectrometry (AAS) for the determination of (82)Se in blood serum from 23 patients. These results suggest that the sample preparative procedure coupled with ICP-MS can be used for the routine determination of (82)Se in human blood serum.

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.

Validation of a HPLC method for determination of hydroxymethylfurfural in crude palm oil.

PubMed

Ariffin, Abdul Azis; Ghazali, H M; Kavousi, Parviz

2014-07-01

For the first time 5-hydroxymethyl-2-furaldehyde (HMF) was separated from crude palm oil (CPO), and its authenticity was determined using an RP-HPLC method. Separation was accomplished with isocratic elution of a mobile phase comprising water and methanol (92:8 v/v) on a Purospher Star RP-18e column (250mm×4.6mm, 5.0μm). The flow rate was adjusted to 1ml/min and detection was performed at 284nm. The method was validated, and results obtained exhibit a good recovery (95.58% to 98.39%). Assessment of precision showed that the relative standard deviations (RSD%) of retention times and peak areas of spiked samples were less than 0.59% and 2.66%, respectively. Further, the limit of detection (LOD) and LOQ were 0.02, 0.05mg/kg, respectively, and the response was linear across the applied ranges. The crude palm oil samples analysed exhibited HMF content less than 2.27mg/kg. Copyright © 2014 Elsevier Ltd. All rights reserved.

Novel spectrophotometric method for determination of cinacalcet hydrochloride in its tablets via derivatization with 1,2-naphthoquinone-4-sulphonate

PubMed Central

2012-01-01

This study represents the first report on the development of a novel spectrophotometric method for determination of cinacalcet hydrochloride (CIN) in its tablet dosage forms. Studies were carried out to investigate the reaction between CIN and 1,2-naphthoquinone-4-sulphonate (NQS) reagent. In alkaline medium (pH 8.5), an orange red-colored product exhibiting maximum absorption peak (λmax) at 490 nm was produced. The stoichiometry and kinetic of the reaction were investigated and the reaction mechanism was postulated. This color-developing reaction was employed in the development of a simple and rapid visible-spectrophotometric method for determination of CIN in its tablets. Under the optimized reaction conditions, Beer's law correlating the absorbance with CIN concentration was obeyed in the range of 3 - 100 μg/ml with good correlation coefficient (0.9993). The molar absorptivity (ε) was 4.2 × 105 l/mol/cm. The limits of detection and quantification were 1.9 and 5.7 μg/ml, respectively. The precision of the method was satisfactory; the values of relative standard deviations (RSD) did not exceed 2%. No interference was observed from the excipients that are present in the tablets. The proposed method was applied successfully for the determination of CIN in its pharmaceutical tablets with good accuracy and precisions; the label claim percentage was 100.80 - 102.23 ± 1.27 - 1.62%. The results were compared favorably with those of a reference pre-validated method. The method is practical and valuable in terms of its routine application in quality control laboratories. PMID:22305461

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%.

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.

Application of an ETV-ICP system for the determination of elements in human hair*1

NASA Astrophysics Data System (ADS)

Plantikow-Voβgätter, F.; Denkhaus, E.

1996-01-01

When determining element contents in hair samples without sample digestion it is necessary to analyze large sample volumes in order to minimize problems of inhomogeneity of biological sample materials. Therefore an electrothermal vaporization system (ETV) is used for solid sample introduction into an inductively coupled plasma (ICP) for the determination of matrix and trace elements in hair. This paper concentrates on the instrumental aspects without time consuming sample preparation. The results obtained for optimization tests, ETV operating parameters and ICP operating parameters, are shown and discussed. Standard additions are used for calibration for the determination of Zn, Mg, and Mn in human hair. Studies including reproducibility and detection limits for chosen elements have been carried out on certified reference materials (CRMs). The determination of reproducibility (relative standard deviation (RSD) of n = 10) and detection limits (DLs) of Zn (RSD < 8.5%, DL < 0.8 μ g -1), Mn (RSD < 14.1%, DL < 0.3 μ g -1), and Mg (RSD < 7.4%, DL < 6.6 μ g -1) are satisfactory. The concentration values found show good agreement with the corresponding certified values. Further sample preparation steps, including hair sampling, washing procedure and homogenization for hair, relating to measurements of real hair samples are described.

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.

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.

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.

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.

Analysis of polybrominated diphenyl ethers and emerging halogenated and organophosphate flame retardants in human hair and nails.

PubMed

Liu, Liang-Ying; Salamova, Amina; He, Ka; Hites, Ronald A

2015-08-07

A method for the digestion, extraction, fractionation, and analysis of three classes of flame retardants, including 36 polybrominated diphenyl ethers (PBDEs), 9 halogenated alternative flame retardants (AFRs), and 12 organophosphate esters (OPEs) in human hair and nail samples was developed. The method employed HNO3/H2O2 digestion, liquid-liquid extraction with (4:1 vol) hexane:dichloromethane, fractionation on a 6g column of 2.5% water deactivated Florisil, and analysis by gas chromatographic mass spectrometry. The accuracy and precision of the method was validated using spiked samples of 6 replicates for both hair and nail samples. The method validation results showed good accuracy and precision for all PBDEs except BDE-209, all AFRs except hexabromobenzene (HBB), and all of the 12 OPEs, with average recovery efficiencies>90% and relative standard deviations (RSDs)<10%. The average recovery efficiencies for HBB were between 60% and 86%, with RSDs<10%. BDE-209 had recovery efficiencies of 64% (RSD, 13%) for hair and 71% (RSD, 10%) for nail. This method was applied to analyze 5 human hair and 5 fingernail samples from the general student population at Indiana University Bloomington campus. BDE-47 and BDE-99 were the predominant PBDEs detected in both hair and nail samples, with a concentration range of 11-620 and 4.6-780ng/g (dry weight) in hair and 7.3-43 and 2.1-11ng/g in nails, respectively. Di-(2-ethylhexyl)-tetrabromophthalate (TBPH) and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB) were detected in all the samples, with concentrations of 20-240 and 11-350ng/g in hair and <17-80 and <9.2-71ng/g in nails, respectively. Among the 12 OPEs analyzed, tris(2-chloroethyl)phosphate (TCEP), tris(1-chloro-2-propyl)phosphate (TCIPP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), and triphenyl phosphate (TPHP) were most often detected. The concentrations of these OPEs (summed together) were 1100-3900 and 380-18,000ng/g in hair and nails, respectively. These levels exceed those of both the PBDEs and the AFRs. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of Glucosamine in Raw Materials and Dietary Supplements Containing Glucosamine Sulfate and/or Glucosamine Hydrochloride by High-Performance Liquid Chromatography with FMOC-Su Derivatization: Collaborative Study

PubMed Central

Zhou, Joseph Ziqi; Waszkuc, Ted; Mohammed, Felicia

2008-01-01

A collaborative study was conducted for determination of glucosamine in raw materials and dietary supplements containing glucosamine sulfate and/or glucosamine hydrochloride by high-performance liquid Chromatography (HPLC) with N-(9-fluorenyl-methoxycarbonyloxy) succinimide (FMOC-Su) derivatization. Thirteen blind materials, one pair of which were duplicates, were tested by 12 collaborating laboratories. The test samples consisted of various commercial products, including tablets, capsules, drink mix, and liquids as well as raw materials, blanks, and those for spike recovery analyses. The tests with blank products and products spiked with glucosamine showed good specificity of the method. The average recoveries at spike levels of 100 and 150% of the declared amount were 99.0% with a relative standard deviation (RSD) of 2.1%, and 101% with an RSD of 2.3%, respectively. The test results between laboratories on each commercial product were reproducible with RSD values of no more than 4.0%, and the results were repeatable in the same laboratory with an average RSD of 0.7%. HorRat values ranged from 0.5 to 1.7 on both tests of spike recovery and reproducibility between laboratories on commercial products. The average determination coefficient of the calibration curves from the laboratories was 0.9995 with an RSD of 0.03%. All of the 12 collaborating laboratories succeeded in the study and none of their reported test results were outliers, partly indicating the robustness of the method. It is recommended that the method be accepted by AOAC INTERNATIONAL as Official First Action. PMID:16152919

Results of microsurgical treatment of large and giant ICA aneurysms using the retrograde suction decompression (RSD) technique: series of 92 patients.

PubMed

Eliava, Shalva S; Filatov, Yuri M; Yakovlev, Sergei B; Shekhtman, Oleg D; Kheireddin, Ali S; Sazonov, Ilya A; Sazonova, Olga B; Okishev, Dmitry N

2010-06-01

Microsurgical treatment of large and giant paraclinoid internal carotid artery (ICA) aneurysms often requires the use of the retrograde suction decompression (RSD) technique to facilitate clipping. Surgical results, functional outcomes at discharge, and technique limitations based on single institution series are presented. Between 1996 and 2009, eighty-three consecutive patients (19 to 68 years, mean 45.5 ± 9.9 years), predominantly women (69 women and 14 men) with large (23 patients, 27.7%) or giant (60 patients, 72.3%) paraclinoid aneurysms were surgically treated with the RSD technique performed by the neck route (62 patients, 74.4%) or later on, by endovascular means (21 patients, 25.3%). Patients were admitted after hemorrhage (48 patients, 57.9%), pseudotumor course (28 patients, 33.7%), mixed symptoms (5 patients, 6%), or asymptomatic (2 patients, 2.4%). In most RSD surgeries (90.4%) aneurysms were successfully excluded: neck was clipped in 57 patients (68.7%) or clipping with ICA reconstruction was achieved in 18 patients (21.7%). In six patients aneurysms were wrapped with glue (7.2%), trapped in one patient (1.2%), and in one patient, ICA balloon deconstruction was performed (1.2%). Good or excellent results (Glasgow Outcome Scale scores 4-5) at discharge were achieved in 69 patients (83.1%), 11 patients (13.3%) remained severely disabled (Glasgow Outcome Scale 3), and 3 patients died (3.6%). Surgical clipping with the RSD method remains a treatment of choice with acceptable outcomes for patients not amenable for endovascular treatment. Copyright © 2010 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

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%).

Development and Validation of a Reversed Phase HPLC Method for Determination of Anacardic Acids in Cashew (Anacardium occidentale) Nut Shell Liquid.

PubMed

Oiram Filho, Francisco; Alcântra, Daniel Barbosa; Rodrigues, Tigressa Helena Soares; Alexandre E Silva, Lorena Mara; de Oliveira Silva, Ebenezer; Zocolo, Guilherme Julião; de Brito, Edy Sousa

2018-04-01

Cashew nut shell liquid (CNSL) contains phenolic lipids with aliphatic chains that are of commercial interest. In this work, a chromatographic method was developed to monitor and quantify anacardic acids (AnAc) in CNSL. Samples containing AnAc were analyzed on a high-performance liquid chromatograph coupled to a diode array detector, equipped with a reversed phase C18 (150 × 4.6 mm × 5 μm) column using acetonitrile and water as the mobile phase both acidified with acetic acid to pH 3.0 in an isocratic mode (80:20:1). The chromatographic method showed adequate selectivity, as it could clearly separate the different AnAc. To validate this method, AnAc triene was used as an external standard at seven different concentrations varying from 50 to 1,000 μg mL-1. The Student's t-test and F-test were applied to ensure high confidence for the obtained data from the analytical calibration curve. The results were satisfactory with respect to intra-day (relative standard deviation (RSD) = 0.60%) and inter-day (RSD = 0.67%) precision, linearity (y = 2,670.8x - 26,949, r2 > 0.9998), system suitability for retention time (RSD = 1.02%), area under the curve (RSD = 0.24%), selectivity and limits of detection (19.8 μg mg-1) and quantification (60.2 μg mg-1). The developed chromatographic method was applied for the analysis of different CNSL samples, and it was deemed suitable for the quantification of AnAc.

Determination of phenol compounds in surface water matrices by bar adsorptive microextraction-high performance liquid chromatography-diode array detection.

PubMed

Neng, Nuno R; Nogueira, José M F

2014-07-03

Bar adsorptive microextraction combined with liquid desorption followed by high performance liquid chromatography with diode array detection (BAµE-LD/HPLC-DAD) is proposed for the determination of trace levels of five phenol compounds (3-nitrophenol, 4-nitrophenol, bisphenol-A, 4-n-octylphenol and 4-n-nonylphenol) in surface water matrices. By using a polystyrene-divinylbenzene copolymer (PS-DVB) sorbent phase, high selectivity and efficiency is achieved even against polydimethylsiloxane through stir bar sorptive extraction. Assays performed by BAµE(PS-DVB)-LD/HPLC-DAD on 25 mL water samples spiked at the 10.0 µg/L levels yielded recoveries over 88.0%±5.7% for all five analytes, under optimized experimental conditions. The analytical performance showed good precision (RSD<15%), detection limits of 0.25 µg/L and linear dynamic ranges (1.0-25.0 μg/L) with determination coefficient higher than 0.9904. By using the standard addition method, the application of the present method to surface water matrices allowed very good performances at the trace level. The proposed methodology proved to be a suitable alternative to monitor phenol compounds in surface water matrices, showing to be easy to implement, reliable, sensitive and requiring a low sample volume.

Development and optimization of the determination of pharmaceuticals in water samples by SPE and HPLC with diode-array detection.

PubMed

Pavlović, Dragana Mutavdžić; Ašperger, Danijela; Tolić, Dijana; Babić, Sandra

2013-09-01

This paper describes the development, optimization, and validation of a method for the determination of five pharmaceuticals from different therapeutic classes (antibiotics, anthelmintics, glucocorticoides) in water samples. Water samples were prepared using SPE and extracts were analyzed by HPLC with diode-array detection. The efficiency of 11 different SPE cartridges to extract the investigated compounds from water was tested in preliminary experiments. Then, the pH of the water sample, elution solvent, and sorbent mass were optimized. Except for optimization of the SPE procedure, selection of the optimal HPLC column with different stationary phases from different manufacturers has been performed. The developed method was validated using spring water samples spiked with appropriate concentrations of pharmaceuticals. Good linearity was obtained in the range of 2.4-200 μg/L, depending on the pharmaceutical with the correlation coefficients >0.9930 in all cases, except for ciprofloxacin (0.9866). Also, the method has revealed that low LODs (0.7-3.9 μg/L), good precision (intra- and interday) with RSD below 17% and recoveries above 98% for all pharmaceuticals. The method has been successfully applied to the analysis of production wastewater samples from the pharmaceutical industry. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Determination of H2S in Rat Intestinal Perfusion Solution Based on Fluorescence Analysis].

PubMed

Hou, Jun-feng; Li, Xin-xia; Shen, Xue-ru; Huojia, Miliban; Guan, Ming

2015-08-01

Under alkaline conditions, Fluorescein mercury has strong fluorescence, however, when it met S(2-), its fluorescence would quench, in view of the above, a fluorescence method for determination of H2S in biological samples was established. In the 0.1 mol · L(-1) NaOH dilution, when the concentration of fluorescein Mercury and Na2S was 5.0 × 10(-5) and 1.0 × 10(-5) mol · L(-1) respectively, the fluorescence intensity of system was determined at 522 nm. The results showed that, at the range of 4.0 × 10(-7)~2.0 × 10(-6) mol · L(-1), the concentration decreasing of H2S and fluorescence intensity had good linear relationship, r=0.9980, the RSD of precision test was 4.59% (n=7), the detection limit was 3.5 × 10(-8) mol · L(-1), the content of H2S in the sample were 1.01 × 10(-6) and 1.15 × 10(-6) mol · L(-1), and the recovery rate was 95.8%~101.0%, the method has the advantages of simple operation, high sensitivity, good selectivity, can accurately determine of H2S in intestinal perfused solution, and provides the basis for the determination of endogenous H2S.

Determination of tributyltin in environmental water matrices using stir bar sorptive extraction with in-situ derivatisation and large volume injection-gas chromatography-mass spectrometry.

PubMed

Neng, N R; Santalla, R P; Nogueira, J M F

2014-08-01

Stir bar sorptive extraction with in-situ derivatization using sodium tetrahydridoborate (NaBH4) followed by liquid desorption and large volume injection-gas chromatography-mass spectrometry detection under the selected ion monitoring mode (SBSE(NaBH4)in-situ-LD/LVI-GC-MS(SIM)) was successfully developed for the determination of tributyltin (TBT) in environmental water matrices. NaBH4 proved to be an effective and easy in-situ speciation agent for TBT in aqueous media, allowing the formation of adducts with enough stability and suitable polarity for SBSE analysis. Assays performed on water samples spiked at the 10.0μg/L, yielded convenient recoveries (68.2±3.0%), showed good accuracy, suitable precision (RSD<9.0%), low detection limits (23ng/L) and excellent linear dynamic range (r(2)=0.9999) from 0.1 to 170.0µg/L, under optimized experimental conditions. By using the standard addition method, the application of the present methodology to real surface water samples allowed very good performance at the trace level. The proposed methodology proved to be a feasible alternative for routine quality control analysis, easy to implement, reliable and sensitive to monitor TBT in environmental water matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

Combining bar adsorptive microextraction with capillary electrophoresis--application for the determination of phenolic acids in food matrices.

PubMed

da Rosa Neng, Nuno; Sequeiros, Rute C P; Florêncio Nogueira, José Manuel

2014-09-01

In this contribution, bar adsorptive microextraction coated with a mixed-mode anion exchange/RP followed by liquid desorption was combined for the first time with a capillary electrophoresis-diode array detection system (BAμE(MAX)-LD/CE-DAD), for the determination of phenolic acids in food matrices, using chlorogenic, ferulic, cumaric, and caffeic acids as model compounds. Assays performed in aqueous media spiked at the 0.8 mg/L level yielded average recoveries up to 40% for all four phenolic acids, under optimized experimental conditions. The analytical performance showed also good precision (RSD < 15%), convenient LODs (18.0-85.0 μg/L) and linear dynamic ranges (0.8-8.0 mg/L) with convenient determination coefficients (r(2) > 0.9900). By using the standard addition method, the application to food matrices such as green tea, red fruit juice, and honey allowed very good performances for the determination of minor amounts of phenolic acids. The proposed methodology proved to be a suitable alternative for the analysis of polar to ionic compounds, showing to be easy to implement, reliable, sensitive, and requiring a low sample volume to determine phenolic acids in food samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

An IC-MS/MS Method for the Determination of 1-Hydroxyethylidene-1,1-diphosphonic Acid on Uncooked Foods Treated with Peracetic Acid-Based Sanitizers.

PubMed

Suzuki, Ippei; Kubota, Hiroki; Ohtsuki, Takashi; Tatebe, Chiye; Tada, Atsuko; Yano, Takeo; Akiyama, Hiroshi; Sato, Kyoko

2016-01-01

A rapid, sensitive, and specific analytical method for the determination of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) on uncooked foods after treatment with a peracetic acid-based sanitizer (PAS) was developed. The method involves simple sample preparation steps and analysis using ion chromatography (IC) coupled with tandem mass spectrometry (MS/MS). The quantification limits of HEDP on uncooked foods are 0.007 mg/kg for vegetables and fruits and 0.2 mg/kg for meats. The recovery and relative standard deviation (RSD) of HEDP analyses of uncooked foods ranged from 73.9 to 103.8% and 1.9 to 12.6%, respectively. The method's accuracy and precision were evaluated by inter-day recovery tests. The recovery for all samples ranged from 93.6 to 101.2%, and the within-laboratory repeatability and reproducibility were evaluated based on RSD values, which were less than 6.9 and 11.5%, respectively. Analyses of PAS-treated fruits and vegetables using the developed method indicated levels of HEDP ranging from 0.008 to 0.351 mg/kg. Therefore, the results of the present study suggest that the proposed method is an accurate, precise, and reliable way to determine residual HEDP levels on PAS-treated uncooked foods.

Development of a Rapid LC-MS/MS Method for the Determination of Emerging Fusarium mycotoxins Enniatins and Beauvericin in Human Biological Fluids

PubMed Central

Serrano, Ana Belén; Capriotti, Anna Laura; Cavaliere, Chiara; Piovesana, Susy; Samperi, Roberto; Ventura, Salvatore; Laganà, Aldo

2015-01-01

A novel method for the simultaneous determination of enniatins A, A1, B and B1 and beauvericin, both in human urine and plasma samples, was developed and validated. The method consisted of a simple and easy pretreatment, specific for each matrix, followed by solid phase extraction (SPE) and detection by high performance liquid chromatography-tandem mass spectrometry with an electrospray ion source. The optimized SPE method was performed on graphitized carbon black cartridges after suitable dilution of the extracts, which allowed high mycotoxin absolute recoveries (76%–103%) and the removal of the major interferences from the matrix. The method was extensively evaluated for plasma and urine samples separately, providing satisfactory results in terms of linearity (R2 of 0.991–0.999), process efficiency (>81%), trueness (recoveries between 85% and 120%), intra-day precision (relative standard deviation, RSD < 18%), inter-day precision (RSD < 21%) and method quantification limits (ranging between 20 ng·L−1 and 40 ng·L−1 in plasma and between 5 ng·L−1 and 20 ng·L−1 in urine). Finally, the highly sensitive validated method was applied to some urine and plasma samples from different donors. PMID:26371043

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 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.

Simultaneous Determination of Multiple Classes of Hydrophilic and Lipophilic Components in Shuang-Huang-Lian Oral Liquid Formulations by UPLC-Triple Quadrupole Linear Ion Trap Mass Spectrometry.

PubMed

Liang, Jun; Sun, Hui-Min; Wang, Tian-Long

2017-11-24

The Shuang-Huang-Lian (SHL) oral liquid is a combined herbal prescription used in the treatment of acute upper respiratory tract infection, acute bronchitis and pneumonia. Multiple constituents are considered to be responsible for the therapeutic effects of SHL. However, the quantitation of the multi-components from multiple classes is still unsatisfactory because of the high complexity of constituents in SHL. In this study, an accurate, rapid, and specific UPLC-MS/MS method was established for simultaneous quantification of 18 compounds from multiple classes in SHL oral liquid formulations. Chromatographic separation was performed on a HSS T3 (1.8 μm, 2.1 mm × 100 mm) column, using a gradient mobile phase system of 0.1% formic acid in acetonitrile and 0.1% formic acid in water at a flow rate of 0.2 mL·min -1 ; the run time was 23 min. The MS was operated in negative electrospray ionization (ESI - ) for analysis of 18 compounds using multiple reaction monitoring (MRM) mode. UPLC-ESI - -MRM-MS/MS method showed good linear relationships ( R ² > 0.999), repeatability (RSD < 3%), precisions (RSD < 3%) and recovery (84.03-101.62%). The validated method was successfully used to determine multiple classes of hydrophilic and lipophilic components in the SHL oral liquids. Finally, principal component analysis (PCA) was used to classify and differentiate SHL oral liquid samples attributed to different manufacturers of China. The proposed UPLC-ESI - -MRM-MS/MS coupled with PCA has been elucidated to be a simple and reliable method for quality evaluation of SHL oral liquids.

Simultaneous determination of V, Ni and Fe in fuel fly ash using solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry.

PubMed

Cárdenas Valdivia, A; Vereda Alonso, E; López Guerrero, M M; Gonzalez-Rodriguez, J; Cano Pavón, J M; García de Torres, A

2018-03-01

A green and simple method has been proposed in this work for the simultaneous determination of V, Ni and Fe in fuel ash samples by solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry (SS HR CS GFAAS). The application of fast programs in combination with direct solid sampling allows eliminating pretreatment steps, involving minimal manipulation of sample. Iridium treated platforms were applied throughout the present study, enabling the use of aqueous standards for calibration. Correlation coefficients for the calibration curves were typically better than 0.9931. The concentrations found in the fuel ash samples analysed ranged from 0.66% to 4.2% for V, 0.23-0.7% for Ni and 0.10-0.60% for Fe. Precision (%RSD) were 5.2%, 10.0% and 9.8% for V, Ni and Fe, respectively, obtained as the average of the %RSD of six replicates of each fuel ash sample. The optimum conditions established were applied to the determination of the target analytes in fuel ash samples. In order to test the accuracy and applicability of the proposed method in the analysis of samples, five ash samples from the combustion of fuel in power stations, were analysed. The method accuracy was evaluated by comparing the results obtained using the proposed method with the results obtained by ICP OES previous acid digestion. The results showed good agreement between them. The goal of this work has been to develop a fast and simple methodology that permits the use of aqueous standards for straightforward calibration and the simultaneous determination of V, Ni and Fe in fuel ash samples by direct SS HR CS GFAAS. Copyright © 2017 Elsevier B.V. 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.

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.

[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.

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.

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.

Determination and confirmation of isopropyl p-toluenesulfonate in cosmetics by HPLC-diode array detector method and GC-MS.

PubMed

Tay, B Y P; Yung, S C; Teoh, T Y

2016-12-01

Isopropyl p-toluenesulfonate (IPTS) is a potentially genotoxic by-product formed during the esterification of palm oil-based palmitic and palm kernel oil-based myristic acid with isopropanol to produce isopropyl palmitate or isopropyl myristate. There are no methods described for the analysis of IPTS in cosmetic products. In this work, we have established a simple, precise and accurate method to determine the presence and level of IPTS in various finished cosmetic products which contain palm-based esters in their formulations. An Agilent 1200 series high-performance liquid chromatography (HPLC) unit using a diode-array detector (DAD) has been employed and optimized to detect IPTS in cosmetic products. For the separation, a reverse-phase Hypersil Gold C8 column (5 μm, 4.6 mm i.d. 250 mm) 5 mM tetrabutylammonium phosphate buffer 50 : 50, (v/v) solution in acetonitrile as mobile phase, in isocratic mode and a flow rate of 0.8 mL min -1 were used. A second method using a gas chromatography/mass selective detector GC-MSD was also developed to confirm the IPTS identity in the cosmetic products. Recoveries of IPTS from cosmetic matrices such as a lotion, cleansing milk and a cream ranged from 94.0% to 101.1% with <5% relative standard deviation (%RSD) showing good accuracy and repeatability of the method. The six-point calibration curves (determined over the range 0.5-50 μg mL -1 ) have a correlation coefficient of 0.9999 (based on HPLC peak area) and 0.9998 (based on HPLC peak height). The intra- and interday precisions (measured by the %RSD) of the method were <2% and <5%, respectively, indicating that the developed method is reliable, precise and reproducible. The detection and quantification limit of the method were found to be 0.5 μg mL -1 and 1.6 μg mL -1 , respectively. Analyses of 83 commercial cosmetics showed no presence of IPTS. The validation data indicated that this method was suitable for the quantitative analysis of IPTS in commercial cosmetics. This method is applicable for analyses of trace levels of IPTS in cosmetics and has the advantage of using only simple sample preparation steps. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Construction and evaluation of ion selective electrodes for nitrate with a summing operational amplifier. Application to tobacco analysis.

PubMed

Pérez-Olmos, R; Rios, A; Fernández, J R; Lapa, R A; Lima, J L

2001-01-05

In this paper, the construction and evaluation of an electrode selective to nitrate with improved sensitivity, constructed like a conventional electrode (ISE) but using an operational amplifier to sum the potentials supplied by four membranes (ESOA) is described. The two types of electrodes, without an inner reference solution, were constructed using tetraoctylammonium bromide as sensor, dibutylphthalate as solvent mediator and PVC as plastic matrix, the membranes obtained directly applied onto a conductive epoxy resin support. After the comparative evaluation of their working characteristics they were used in the determination of nitrate in different types of tobacco. The limit of detection of the direct potentiometric method developed was found to be 0.18 g kg(-1) and the precision and accuracy of the method, when applied to eight different samples of tobacco, expressed in terms of mean R.S.D. and average percentage of spike recovery was 0.6 and 100.3%, respectively. The comparison of variances showed, on all ocassions, that the results obtained by the ESOA were similar to those obtained by the conventional ISE, but with higher precision. Linear regression analysis showed good agreement (r=0.9994) between the results obtained by the developed potentiometric method and those of a spectrophotometric method based on brucine, adopted as reference method, when applied simultaneously to 32 samples of different types of tobacco.

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.

Development and validation of an ultra-performance convergence chromatography method for the quality control of Angelica gigas Nakai.

PubMed

Kim, Hyo Seon; Chun, Jin Mi; Kwon, Bo-In; Lee, A-Reum; Kim, Ho Kyoung; Lee, A Yeong

2016-10-01

Ultra-performance convergence chromatography, which integrates the advantages of supercritical fluid chromatography and ultra high performance liquid chromatography technologies, is an environmentally friendly analytical method that uses dramatically reduced amounts of organic solvents. An ultra-performance convergence chromatography method was developed and validated for the quantification of decursinol angelate and decursin in Angelica gigas using a CSH Fluoro-Phenyl column (2.1 mm × 150 mm, 1.7 μm) with a run time of 4 min. The method had an improved resolution and a shorter analysis time in comparison to the conventional high-performance liquid chromatography method. This method was validated in terms of linearity, precision, and accuracy. The limits of detection were 0.005 and 0.004 μg/mL for decursinol angelate and decursin, respectively, while the limits of quantitation were 0.014 and 0.012 μg/mL, respectively. The two components showed good regression (correlation coefficient (r 2 ) > 0.999), excellent precision (RSD < 2.28%), and acceptable recoveries (99.75-102.62%). The proposed method can be used to efficiently separate, characterize, and quantify decursinol angelate and decursin in Angelica gigas and its related medicinal materials or preparations, with the advantages of a shorter analysis time, greater sensitivity, and better environmental compatibility. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

[Determination of aspirin and free salicylic acid in lysinipirine injection by high performance liquid chromatography].

PubMed

Dong, Yu; Zhao, Yuan-zheng; Zhang, Yi-na

2002-05-01

The contents of aspirin and free salicylic acid in lysinipirine injection were determined by high performance liquid chromatography (HPLC). A Hypersil BDS C18 column was used with the mobile phase of methanol-water-acetic acid (35:65:3, volume ratio) and the detection wavelength of 280 nm. The average recoveries of aspirin and salicylic acid added were 99.27% (RSD = 0.8%) and 99.61%(RSD = 1.3%), respectively. The calibration curves had good linearity in the range of 0.028 g/L -0.141 mg/L and 0.77 mg/L -3.85 mg/L, and the correlation coefficients were 0.9999 and 0.9998 for aspirin and salicylic acid respectively.

Determination of Five Chemical Markers in DF Formula, the Herbal Composition of Ephedra intermedia, Rheum palmatum, and Lithospermum erythrorhizon, Using High-performance Liquid Chromatography-ultraviolet Detection.

PubMed

Jeong, Birang; Roh, Jong Seong; Yoon, Michung; Yoon, Yoosik; Shin, Soon Shik; Cho, Hyun Joo; Kwon, Yong Soo; Yang, Heejung

2018-01-01

DF formula is a herbal preparation comprised three medicinal herbs, namely, Ephedra intermedia , Rheum palmatum , and Lithospermum erythrorhizon , which is being used for the treatment of obesity and liver fibrosis in Korean local clinics. Since the abovementioned three herbs exist with different proportions in DF formula and their chemical markers have different physiochemical properties; it is quite challenging to develop an analytical methodology for the determination of these chemical markers. For the analysis of the three herbs, five chemicals, (+)-pseudoephedrine (1) and (-)-ephedrine (2) for E. intermedia , aloe-emodin (3), and chrysophanol (4) for R. palmatum , and shikonin (5) for L. erythrorhizon , were selected for method validation of DF formula, and the analytical conditions were optimized and validated using high-performance liquid chromatography coupled with an ultraviolet detector (HPLC-UV). The specificities for the five compounds 1-5 were determined by their UV absorption spectra (1-4: 215 nm and 5: 520 nm). Their calibration curves showed good linear regressions with high correlation coefficient values ( R 2 > 0.9997). The limits of detection of these five markers were in the range 0.4-2.1 ng/mL, with the exception of 5 (12.7 ng/mL). The intraday variability for all the chemical markers was less than a Relative standard deviation (RSD) of 3%, except for 5 (RSD = 12.6%). In the case of interday analysis, 1 (1.0%), 2 (3.1%), and 4 (3.7%) showed much lower variabilities (RSD < 5%) than 3 (7.6%) and 5 (8.2%). Moreover, the five chemical markers showed good recoveries with good accuracies in the range of 90%-110%. The developed HPLC-UV method for the determination of the five chemical markers of the components of DF formula was validated. DF formula, the herbal composition of Ephedra intermedia , Rheum palmatum and Lithospermum erythrorhizon Five chemical markers in DF formula were (+)-pseudoephedrine (1) and (-)-ephedrine (2) for E. intermedia , aloe-emodin (3) and chrysopanol (4) for R. palmatum , and shikonin (5) for L. erythrorhizon , with quite different physico-chemical propertiesFive chemical markers in DF formula were determined by HPLC-UV Abbreviations used: EP: (-)-ephedrine; PSEP: (+)-pseudoephedrine; HPLC: High-performance liquid chromatography; UV: Ultraviolet; LOD: Limit of detection; LOQ: Limit of quantification; RSD: Relative standard deviation.

Validation of a reversed-phase high-performance liquid chromatographic method for the determination of free amino acids in rice using l-theanine as the internal standard.

PubMed

Liyanaarachchi, G V V; Mahanama, K R R; Somasiri, H P P S; Punyasiri, P A N

2018-02-01

The study presents the validation results of the method carried out for analysis of free amino acids (FAAs) in rice using l-theanine as the internal standard (IS) with o-phthalaldehyde (OPA) reagent using high-performance liquid chromatography-fluorescence detection. The detection and quantification limits of the method were in the range 2-16μmol/kg and 3-19μmol/kg respectively. The method had a wide working range from 25 to 600μmol/kg for each individual amino acid, and good linearity with regression coefficients greater than 0.999. Precision measured in terms of repeatability and reproducibility, expressed as percentage relative standard deviation (% RSD) was below 9% for all the amino acids analyzed. The recoveries obtained after fortification at three concentration levels were in the range 75-105%. In comparison to l-norvaline, findings revealed that l-theanine is suitable as an IS and the validated method can be used for FAA determination in rice. Copyright © 2017 Elsevier Ltd. All rights reserved.

A new validated analytical method for the determination of tributyltin in water samples at the quantification level set by the European Union.

PubMed

Devos, Christophe; David, Frank; Sandra, Pat

2012-10-26

According to recent directives of the European Union (EU), limits of quantification (LOQ) for the determination of tributyltin (TBT) in surface waters should be ca. 60 pg/L (ppq). This put very stringent requirements on analytical methodologies; definitely when they have to be applied in a routine environment. Stir bar sorptive extraction (SBSE), followed by thermal desorption (TD) and capillary gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) can provide accurate and precise data at the 2 ng/L level (ppt). For lower concentrations, matrix and reagent interferences together with contamination may provide too high TBT values. A two-dimensional heart-cut GC method was developed to fractionate TBT from interferences. The GC-GC-MS/MS method shows excellent linearity in the range 50 pg/L-4 ng/L, good repeatability (RSD<20% at 200 pg/L), and a limit of detection of 11 pg/L. The method performance is demonstrated with representative samples i.e. harbor water and waste water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of a multiresidue method for the determination of endocrine disrupters in fish fillet using gas chromatography-triple quadrupole tandem mass spectrometry.

PubMed

Munaretto, Juliana S; Ferronato, Giovana; Ribeiro, Lucila C; Martins, Manoel L; Adaime, Martha B; Zanella, Renato

2013-11-15

Endocrine Disrupter Compounds (EDCs) are responsible for alterations in the endocrine system functions. Aquatic organisms are able to accumulate EDCs residues, being the major source of contamination for top predators and human consumers. This study aimed to develop and validate a method for the determination of 40 EDCs in fish fillet using modified QuEChERS and Gas Chromatography coupled with Mass Spectrometry in tandem (GC-MS/MS). A factorial design was used to optimize the extraction procedure. Method validation presented recoveries from 70.1% to 120.0% with RSD<20% and method limit of detection ranged from 0.3 to 7.5 µg kg(-1), showing good accuracy and precision. This method was successfully applied to the analysis of fish fillet from different species and residues of bisphenol A, chlorpyrifos and bifenthrin were detected. The proposed method proved to be effective for the determination of EDCs in fish fillet at very low concentration levels. © 2013 Elsevier B.V. All rights reserved.

Determination of artificial sweeteners in water samples by solid-phase extraction and liquid chromatography-tandem mass spectrometry.

PubMed

Ordóñez, Edgar Y; Quintana, José Benito; Rodil, Rosario; Cela, Rafael

2012-09-21

The development and performance evaluation of an analytical method for the determination of six artificial sweeteners in environmental waters using solid-phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry are presented. To this end, different SPE alternatives have been evaluated: polymeric reversed-phase (Oasis HLB, Env+, Plexa and Strata X), and mixed-mode with either weak (Oasis WAX) or strong anionic-exchange (Oasis MAX and Plexa PAX) sorbents. Among them, reversed-phase sorbents, particularly Oasis HLB and Strata X, showed the best performance. Oasis HLB provided good trueness (recoveries: 73-112%), precision (RSD<10%) and limits of quantification (LOQ: 0.01-0.5 μg/L). Moreover, two LC separation mechanisms were evaluated: reversed-phase (RPLC) and hydrophilic interaction (HILIC), with RPLC providing better performance than HILIC. The final application of the method showed the presence of acesulfame, cyclamate, saccharin and sucralose in the wastewater and surface water samples analyzed at concentrations up to 54 μg/L. Copyright © 2012 Elsevier B.V. All rights reserved.

Method of low tantalum amounts determination in niobium and its compounds by ICP-OES technique.

PubMed

Smolik, Marek; Turkowska, Magdalena

2013-10-15

A method of determination of low amounts of tantalum in niobium and niobium compounds without its prior separation by means of inductively coupled plasma optical emission spectrometry (ICP-OES) has been worked out. The method involves dissolution of the analyzed samples of niobium as well as its various compounds (oxides, fluorides, chlorides, niobates(V)) in fluoride environments, precipitation of sparingly soluble niobic(tantalic) acid (Nb2O5(Ta2O5) · xH2O), converting them into soluble complex compounds by means of oxalic acid with addition of hydrogen peroxide and finally analyzing directly obtained solutions by ICP-OES. This method permits determination of Ta in niobium at the level of 10(-3)% with relatively good precision (≤ 8% RSD) and accuracy (recovery factor: 0.9-1.1). Relative differences in the results obtained by two independent methods (ICP-OES and ICP-MS) do not exceed 14%, and other elements present in niobium compounds (Ti, W, Zr, Hf, V, Mo, Fe, Cr) at the level of 10(-2)% do not affect determination. © 2013 Elsevier B.V. All rights reserved.

Banana peel as an adsorbent for removing atrazine and ametryne from waters.

PubMed

Silva, Claudineia R; Gomes, Taciana F; Andrade, Graziela C R M; Monteiro, Sergio H; Dias, Ana C R; Zagatto, Elias A G; Tornisielo, Valdemar L

2013-03-13

The feasibility of using banana peel for removal of the pesticides atrazine and ametryne from river and treated waters has been demonstrated, allowing the design of an efficient, fast, and low-cost strategy for remediation of polluted waters. The conditions for removal of these pesticides in a laboratory scale were optimized as sample volume = 50 mL, banana mass = 3.0 g, stirring time = 40 min, and no pH adjustment necessary. KF(sor) values for atrazine and ametryne were evaluated as 35.8 and 54.1 μg g(-1) (μL mL(-1)) by using liquid scintillation spectrometry. Adsorption was also evaluated by LC-ESI-MS/MS. As quantification limits were 0.10 and 0.14 μg L(-1) for both pesticides, sample preconcentration was not needed. Linear analytical curves (up to 10 μg L(-1)), precise results (RSD < 4.5%), good recoveries (82.9-106.6%), and a > 90% removal efficiency were attained for both pesticides. Water samples collected near an intensively cultivated area were adequately remedied.

Determination of lysine content based on an in situ pretreatment and headspace gas chromatographic measurement technique.

PubMed

Wan, Xiao-Fang; Liu, Bao-Lian; Yu, Teng; Yan, Ning; Chai, Xin-Sheng; Li, You-Ming; Chen, Guang-Xue

2018-05-01

This work reports on a simple method for the determination of lysine content by an in situ sample pretreatment and headspace gas chromatographic measurement (HS-GC) technique, based on carbon dioxide (CO 2 ) formation from the pretreatment reaction (between lysine and ninhydrin solution) in a closed vial. It was observed that complete lysine conversion to CO 2 could be achieved within 60 min at 60 °C in a phosphate buffer medium (pH = 4.0), with a minimum molar ratio of ninhydrin/lysine of 16. The results showed that the method had a good precision (RSD < 5.23%) and accuracy (within 6.80%), compared to the results measured by a reference method (ninhydrin spectroscopic method). Due to the feature of in situ sample pretreatment and headspace measurement, the present method becomes very simple and particularly suitable to be used for batch sample analysis in lysine-related research and applications. Graphical abstract The flow path of the reaction and HS-GC measurement for the lysine analysis.

Determination of the content of alkyl ketene dimer in its latex by an ionic-liquid assisted headspace gas chromatography.

PubMed

Yan, Ning; Wan, Xiao-Fang; Chai, Xin-Sheng; Chen, Run-Quan; Chen, Chun-Xia

2017-12-29

This paper reports on an ionic-liquid assisted headspace gas chromatographic (HS-GC) for the determination of the content of alkyl ketene dimer (AKD) in its latex samples, in which the GC system was equipped with a thermal conductivity detector (TCD). The method was based on the AKD hydrolysis conducted in 1-butyl-3-methylimidazolium chloride (ionic-liquid) added medium at 100°C for 10min in a closed headspace sample vial, and the measured CO 2 (the resulting product of the hydrolysis) by HS-GC. The results showed that the present method has a good measurement precision (RSD <2.3%) and accuracy (recoveries from 96 - 105%), and the limit of quantitation (LOQ) is 0.9%. The present method is very suitable to be used for the routine check of AKD content in its latex sample in mill applications. The study also showed that the content of AKD in the tested commercial latex samples were in the range of 3.5-12%. Copyright © 2017 Elsevier B.V. All rights reserved.

[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.

Rapid and selective determination of free chlorine in aqueous solution using electrophilic addition to styrene by gas chromatography/mass spectrometry.

PubMed

Wakigawa, Kengo; Gohda, Akinaga; Fukushima, Sunao; Mori, Takeshi; Niidome, Takuro; Katayama, Yoshiki

2013-01-15

We developed a rapid and selective method for determination of free chlorine in aqueous solution by gas chromatography/mass spectrometry for the first time. Free chlorine was converted to styrene chlorohydrin using electrophilic addition to styrene in sodium acetate buffer solution (pH 5). The chlorine derivative obtained was extracted with chloroform, and then analyzed by GC/MS. The calibration curve showed good linearity from 0.2-100 μg/mL (as available chlorine). The detection limit was 0.1 μg/mL, and the intra- and interday accuracy were measured at concentrations of 10, 50, and 75 μg/mL to be -1.3 to 6.9% (intraday) and 3.8-8.0% (interday) as % Bias. The precision was between 1.4 and 4.5% as % RSD. These results indicate that this method is a superior technique for the identification of free chlorine. This method was successfully applied to quantification in commercial samples and in samples of a criminal case. Copyright © 2012 Elsevier B.V. All rights reserved.

Molecularly imprinted polymer online solid-phase extraction coupled with high-performance liquid chromatography-UV for the determination of three sulfonamides in pork and chicken.

PubMed

He, Jinxing; Wang, Shuo; Fang, Guozhen; Zhu, Huaping; Zhang, Yan

2008-05-14

A selective imprinted amino-functionalized silica gel sorbent was prepared by combining a surface molecular imprinting technique with a sol-gel process for online solid-phase extraction-HPLC determination of three trace sulfonamides in pork and chicken muscle. The imprinted functionalized silica gel sorbent exhibited selectivity and fast kinetics for the adsorption and desorption of sulfonamides. With a sample loading flow rate of 4 mL min (-1) for 12.5 min, enhancement factors and detection limits for three sulfonamides ( S/ N = 3) were achieved. The precision (RSD) for nine replicate online sorbent extractions of 5 microg L (-1) sulfonamides was less than 4.5%. The sorbent also offered good linearity ( r (2) > 0.99) for online solid-phase extraction of trace levels of sulfonamides. The method was applied to the determination of sulfonamides in pork and chicken muscle samples. The prepared polymer sorbent shows promise for online solid-phase extraction for HPLC determination of trace levels of sulfonamides in pork and chicken samples.

Naked eye screening of 11 phenolic compounds and colorimetric determination using polydiacetylene vesicles with α-cyclodextrin

NASA Astrophysics Data System (ADS)

Anekthirakun, Pimpimon; Sukwattanasinitt, Mongkol; Tuntulani, Thawatchai; Imyim, Apichat

2013-07-01

The colorimetric response (CR) of poly(10,12-pentacosadiynoic acid) vesicles (PPCDA) induced by α-cyclodextrin (α-CD) in an aqueous solution has been studied. Various parameters affecting the CR, such as response time and concentration were investigated. The blue color of 0.01 mM PPCDA solution became pinkish red with the addition of α-CD at the concentration higher than 3 mM. The inhibition of the color transition from blue to red was investigated using 11 phenolic compounds. The color transition could be inhibited and observed by naked eye in the presence of 4 phenolic compounds, i.e. 4-nitrophenol (4-NP) and 4-bromophenol (4-BP) and 4-chlorophenol (4-CP) and 3-nitrophenol (3-NP). A colorimetric method for the determination of these compounds was validated and applied for surface water analysis. The linear range from the plot of CR against phenolic compounds concentration was in the order of 0.5-2.0 mM with R2 more than 0.99. The recoveries were 90-95% with good precision (1-4%RSD, n = 10).

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 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 Quantitative Analysis of Naringenin in the Fruit Bodies of Inonotus vaninii by Two-phase Acid Hydrolysis Followed by Reversed Phase-high Performance Liquid Chromatography-ultra Violet.

PubMed

Guohua, Xia; Pan, Ruirong; Bao, Rui; Ge, Yanru; Zhou, Cunshan; Shen, Yuping

2017-01-01

Sanghuang is one of mystical traditional Chinese medicines recorded earliest 2000 years ago, that included various fungi of Inonotus genus and was well-known for antitumor effect in modern medicine. Inonotus vaninii is grown in natural forest of Northeastern China merely and used as Sanghuang commercially, but it has no quality control specification until now. This study was to establish a rapid method of two-phase acid hydrolysis followed by reversed phase-high performance liquid chromatography-ultra violet (RP-HPLC-UV) to quantify naringenin in the fruit body of I. vaninii . Sample solution was prepared by pretreatment of raw material in two-phase acid hydrolysis and the hydrolysis technology was optimized. After reconstitution, analysis was performed using RP-HPLC-UV. The method validation was investigated and the naringenin content of sample and comparison were determined. The naringenin was obtained by two-phase acid hydrolysis method, namely, 10.0 g of raw material was hydrolyzed in 200 mL of 1% sulfuric acid aqueous solution (v/v) and 400 mL of chloroform in oil bath at 110°C for 2 h. Good linearity ( r = 0.9992) was achieved between concentration of analyte and peak area. The relative standard deviation (RSD) of precision was 2.47% and the RSD of naringenin contents for repeatability was 3.13%. The accuracy was supported with recoveries at 96.37%, 97.30%, and 99.31%. The sample solution prepared using the proposed method contained higher content of naringenin than conventional method and was stable for 8 h. Due to the high efficiency of sample preparation and high reliability of the HPLC method, it is feasible to use this method for routine analysis of naringenin in the fungus. A convenient two-phase acid hydrolysis was employed to produce naringenin from raw material, and then an efficient and reliable reversed phase-high performance liquid chromatography-ultra violet method was established to monitor naringenin in the fruit bodies of Inonotus vaninii . The newly established method could be used to control the quality of the herb. Abbreviations used: RP-HPLC-UV: Reversed Phase-High Performance Liquid Chromatography-Ultra Violet, RSD: Relative Standard Deviation, EtOAc: Ethyl acetate, ACN: Acetonitrile, MeOH: Methanol, RH: Relative Humility.

Optimization of Analytical Conditions for a Rapid Determination of Aniline in Environmental Water by Liquid Chromatography/Tandem Mass Spectrometry.

PubMed

Furukawa, Koji; Hashimoto, Makoto; Kaneco, Satoshi

2017-01-01

A rapid determination of aniline in environmental water was examined based on liquid chromatography/tandem mass spectrometry (LC/MS/MS). Environmental water samples were diluted 20-fold with Mill-Q water and measured by LC/MS/MS after adding a surrogate substance (aniline-d 5 ). In the results of the present study, the calibration curve of aniline showed good linearity in the range of 0.05 - 2.0 μg/L. Since the RSD (repeatability) by measuring repeatedly an aniline standard solution (0.05 μg/L, n = 7) was 3.2%, the repeatability of this work was very excellent. In addition, the recovery rate of aniline in environmental water was in the range of 99.0 - 102% with RSD 3.4 - 7.7%, and very good recovery test results were obtained. From these results, this analytical method was confirmed to be effective for aniline measurements of environmental water samples. Also, it is possible to conduct rapid analyses of aniline in environmental water without any solid-phase extraction process, compared to the solid-phase extraction-GC/MS method.

Permethylated-β-Cyclodextrin Capped CdTe Quantum Dot and its Sensitive Fluorescence Analysis of Malachite Green.

PubMed

Cao, Yujuan; Wei, Jiongling; Wu, Wei; Wang, Song; Hu, Xiaogang; Yu, Ying

2015-09-01

In the present work, the CdTe quantum dots were covalently conjugated with permethylated-β-cyclodextrin (OMe-β-CD) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as cross-linking reagent. The obtained functional quantum dots (OMe-β-CD/QDs) showed highly luminescent, water solubility and photostability as well as good inclusion ability to malachite green. A sensitive fluorescence method was developed for the analysis of malachite green in different samples. The good linearity was 2.0 × 10(-7)-1.0 × 10(-5) mol/L and the limit of detect was 1.7 × 10(-8) mol/L. The recoveries for three environmental water samples were 92.0-108.2 % with relative standard deviation (RSD) of 0.24-1.87 %, while the recovery for the fish sample was 94.3 % with RSD of 1.04 %. The results showed that the present method was sensitive and convenient to determine malachite green in complex samples. Graphical Abstract The analytical mechanism of OMe-β-CD/QDs and its linear response to MG.

A coastal three-dimensional water quality model of nitrogen in Jiaozhou Bay linking field experiments with modelling.

PubMed

Lu, Dongliang; Li, Keqiang; Liang, Shengkang; Lin, Guohong; Wang, Xiulin

2017-01-15

With anthropogenic changes, the structure and quantity of nitrogen nutrients have changed in coastal ocean, which has dramatically influenced the water quality. Water quality modeling can contribute to the necessary scientific grounding of coastal management. In this paper, some of the dynamic functions and parameters of nitrogen were calibrated based on coastal field experiments covering the dynamic nitrogen processes in Jiaozhou Bay (JZB), including phytoplankton growth, respiration, and mortality; particulate nitrogen degradation; and dissolved organic nitrogen remineralization. The results of the field experiments and box model simulations showed good agreement (RSD=20%±2% and SI=0.77±0.04). A three-dimensional water quality model of nitrogen (3DWQMN) in JZB was improved and the dynamic parameters were updated according to field experiments. The 3DWQMN was validated based on observed data from 2012 to 2013, with good agreement (RSD=27±4%, SI=0.68±0.06, and K=0.48±0.04), which testifies to the model's credibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of visual distortions in age-related macular degeneration: emergence of new approaches

PubMed Central

Vazquez, Noelia Pitrelli; Knox, Paul C.

2016-01-01

Aims With the arrival of effective treatments for neovascular age-related macular degeneration (nvAMD) there is a need to find improved tests that would allow early detection. Ideally, these tests would allow monitoring of vision by patients themselves from home. The aim of this review is to discuss the available evidence for two recently developed vision tests designed for this purpose: the Preferential Hyperacuity Perimeter (PHP) test and the Radial Shape Discrimination (RSD) test. Methods Articles that investigated detection of nvAMD were reviewed. The methodology of the clinical evidence, where available, was judged for bias and applicability of the results to the general population using the QUADAS-2 quality assessment tool. Results The PHP test has proved to be good at detecting nvAMD but many studies assessed in this review were biased in the selection of patients, restricting the results to only those patients who can use the test and produce reliable results. On the other hand the RSD test is a simple test, well accepted by elderly patients with AMD. However, clinical studies to determine its value in the detection of early signs of nvAMD are still required. Conclusions To date, more studies have investigated the utility of the PHP test compared with the RSD test for detection of nvAMD. Both tests show promise but further evidence is needed to determine the real generalisability of the PHP test and the sensitivity of the RSD test. PMID:27738450

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.

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.

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.

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

Multianalyte imaging in one-shot format sensors for natural waters.

PubMed

Lapresta-Fernández, A; Huertas, Rafael; Melgosa, Manuel; Capitán-Vallvey, L F

2009-03-23

A one-shot multisensor based on ionophore-chromoionophore chemistry for optical monitoring of potassium, magnesium and hardness in water is presented. The analytical procedure uses a black and white non-cooled CCD camera for image acquisition of the one-shot multisensor after reaction, followed by data treatment for quantitation using the grey value pixel average from a defined region of interest from each sensing area to build the analytical parameter 1-alpha. In optimised experimental conditions, the procedure shows a large linear range, up to 6 orders using the linearised model and good detection limits: 9.92 x 10(-5)mM, 1.86 x 10(-3)mM and 1.30 x 10(-2)mgL(-1) of CaCO(3) for potassium, magnesium and hardness, respectively. This analysis system exhibits good precision in terms of relative standard deviation (RSD%) from 2.3 to 3.8 for potassium, from 5.0 to 6.8 for magnesium and from 5.4 to 5.9 for hardness. The trueness of this multisensor procedure was demonstrated comparing it with results obtained by a DAD spectrophotometer used as a reference. Finally, it was satisfactorily applied to the analysis of these analytes in miscellaneous samples, such as water and beverage samples from different origins, validating the results against atomic absorption spectrometry (AAS) as the reference procedure.

Simultaneous chiral discrimination of multiple profens by cyclodextrin-modified capillary electrophoresis in normal and reversed polarity modes.

PubMed

La, Sookie; Kim, Jiyung; Kim, Jung-Han; Goto, Junichi; Kim, Kyoung-Rae

2003-08-01

Simultaneous enantioseparations of nine profens for their accurate chiral discrimination were achieved by capillary electrophoresis (CE) in the normal polarity (NP) mode with a single cyclodextrin (CD) system and in the reversed polarity (RP) mode with a dual CD system. The single CD system in the NP mode employed heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMbetaCD) added at 75 mM-100 mM 2-(N-morpholino)ethanesulfonic acid buffer (pH 6.0) as the optimum run buffer. The dual CD system operated in the RP mode used 30 mM TMbetaCD and 1.0% anionic carboxymethyl-beta-cyclodextrin dissolved in pH 3.0, 100 mM phosphoric acid-triethanolamine buffer containing 0.01% hexadimethrine bromide added to reverse the electroosmotic flow. Fairly good enantiomeric resolutions and the opposite enantiomer migration orders were achieved in the two modes. Relative migration times to internal standard under respective optimum conditions were characteristic of each enantiomer with good precision (< 2% relative standard deviation, RSD), thereby enabling to crosscheck the chemical identification of profens and also their accurate chiralities. The method linearity in the two modes was found to be adequate (r > or = 0.9991) for the chiral assay of the profens investigated. Simultaneous enantiomeric purity test of ibuprofen, ketoprofen and flurbiprofen in a mixture was feasible in a single analysis by the present method.

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

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.

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.

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.

Powdered activated carbons as effective phases for bar adsorptive micro-extraction (BAμE) to monitor levels of triazinic herbicides in environmental water matrices.

PubMed

Neng, N R; Mestre, A S; Carvalho, A P; Nogueira, J M F

2011-02-15

Bar adsorptive micro-extraction using three powdered activated carbons (ACs) as adsorbent phases followed by liquid desorption and high performance liquid chromatography with diode array detection (BAμE(ACs)-LD/HPLC-DAD), was developed to monitor triazinic herbicides (atrazine, simazine and terbutylazine) in environmental water matrices. ACs used present apparent surface areas around 1000 m(2) g(-1) with an important mesoporous volume and distinct surface chemistry characteristics (pH(PZC) ranging from 6.5 to 10.4). The textural and surface chemistry properties of the ACs adsorbent phases were correlated with the analytical data for a better understanding of the overall enrichment process. Assays performed on 10 mL water samples spiked at the 10.0 μg L(-1) levels under optimized experimental conditions yielded recoveries around 100% for the three herbicides under study. The analytical performance showed good precision (RSD<15.0%), convenient detection limits (≈0.1 μg L(-1)) and suitable linearity (1.0-12.0 μg L(-1)) with good correlation coefficients (r(2)>0.9914). By using the standard addition method, the application of the present method on real water matrices, such as surface water and wastewater, allowed very good performances at the trace level. The proposed methodology proved to be a suitable sorptive extraction alternative for the analysis of priority pollutants with polar characteristics, showing to be easy to implement, reliable, sensitive and requiring a low sample volume to monitor triazinic compounds in water matrices. Copyright © 2010 Elsevier B.V. All rights reserved.

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

[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.

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

Determination of Five Chemical Markers in DF Formula, the Herbal Composition of Ephedra intermedia, Rheum palmatum, and Lithospermum erythrorhizon, Using High-performance Liquid Chromatography-ultraviolet Detection

PubMed Central

Jeong, Birang; Roh, Jong Seong; Yoon, Michung; Yoon, Yoosik; Shin, Soon Shik; Cho, Hyun Joo; Kwon, Yong Soo; Yang, Heejung

2018-01-01

Background: DF formula is a herbal preparation comprised three medicinal herbs, namely, Ephedra intermedia, Rheum palmatum, and Lithospermum erythrorhizon, which is being used for the treatment of obesity and liver fibrosis in Korean local clinics. Objective: Since the abovementioned three herbs exist with different proportions in DF formula and their chemical markers have different physiochemical properties; it is quite challenging to develop an analytical methodology for the determination of these chemical markers. Materials and Methods: For the analysis of the three herbs, five chemicals, (+)-pseudoephedrine (1) and (−)-ephedrine (2) for E. intermedia, aloe-emodin (3), and chrysophanol (4) for R. palmatum, and shikonin (5) for L. erythrorhizon, were selected for method validation of DF formula, and the analytical conditions were optimized and validated using high-performance liquid chromatography coupled with an ultraviolet detector (HPLC-UV). Results: The specificities for the five compounds 1–5 were determined by their UV absorption spectra (1–4: 215 nm and 5: 520 nm). Their calibration curves showed good linear regressions with high correlation coefficient values (R2 > 0.9997). The limits of detection of these five markers were in the range 0.4–2.1 ng/mL, with the exception of 5 (12.7 ng/mL). The intraday variability for all the chemical markers was less than a Relative standard deviation (RSD) of 3%, except for 5 (RSD = 12.6%). In the case of interday analysis, 1 (1.0%), 2 (3.1%), and 4 (3.7%) showed much lower variabilities (RSD < 5%) than 3 (7.6%) and 5 (8.2%). Moreover, the five chemical markers showed good recoveries with good accuracies in the range of 90%–110%. Conclusions: The developed HPLC-UV method for the determination of the five chemical markers of the components of DF formula was validated. SUMMARY DF formula, the herbal composition of Ephedra intermedia, Rheum palmatum and Lithospermum erythrorhizonFive chemical markers in DF formula were (+)-pseudoephedrine (1) and (-)-ephedrine (2) for E. intermedia, aloe-emodin (3) and chrysopanol (4) for R. palmatum, and shikonin (5) for L. erythrorhizon, with quite different physico-chemical propertiesFive chemical markers in DF formula were determined by HPLC-UV Abbreviations used: EP: (−)-ephedrine; PSEP: (+)-pseudoephedrine; HPLC: High-performance liquid chromatography; UV: Ultraviolet; LOD: Limit of detection; LOQ: Limit of quantification; RSD: Relative standard deviation. PMID:29720825

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.

Investigation of interaction studies of cefpirome with ACE-inhibitors in various buffers

NASA Astrophysics Data System (ADS)

Nawaz, Muhammad; Arayne, Muhammad Saeed; Sultana, Najma; Abbas, Hira Fatima

2015-02-01

This work describes a RP-HPLC method for the determination and interaction studies of cefpirome with ACE-inhibitors (captopril, enalapril and lisinopril) in various buffers. The separation and interaction of cefpirome with ACE-inhibitors was achieved on a Purospher Star, C18 (5 μm, 250 × 4.6 mm) column. Mobile phase consisted of methanol: water (80:20, v/v, pH 3.3); however, for the separation of lisinopril, it was modified to methanol-water (40:60, v/v, pH 3.3) and pumped at a flow rate of 1 mL min-1. In all cases, UV detection was performed at 225 nm. Interactions were carried out in physiological pH i.e., pH 1 (simulated gastric juice), 4 (simulated full stomach), 7.4 (blood pH) and 9 (simulated GI), drug contents were analyzed by reverse phase high performance liquid chromatography. Method was found linear in the concentration range of 1.0-50.0 μg mL-1 with correlation coefficient (r2) of 0.999. Precision (RSD%) was less than 2.0%, indicating good precision of the method and accuracy was 98.0-100.0%. Furthermore, cefpirome-ACE-inhibitors' complexes were also synthesized and results were elucidated on the basis of FT-IR, and 1H NMR. The interaction results show that these interactions are pH dependent and for the co-administration of cefpirome and ACE-inhibitors, a proper interval should be given.

The application of microwave digestion in decomposing some refractory ore samples with solid fusion agent.

PubMed

Lu, Yan; Li, Gang; Liu, Wei; Yuan, Hongyan; Xiao, Dan

2018-08-15

It is known that most of the refractory ore are the basis of national economy and widely applied in various fields, however, the complexity of the chemical composition and the diversity of the crystallinity in the mineral phases make the sample pre-treatment of refractory ore still remains a challenge. In this work, the complete decomposition of the refractory ore sample can be achieved just by exposing the solid fusion agent and the refractory ore sample in the microwave irradiation environment for a few minutes, and induced by a drop of water. A digestion time of 15 min for 3.0 g solid fusion agent mixture of sodium peroxide/sodium carbonate (Na 2 O 2 /Na 2 CO 3 ) in a corundum crucible via microwave heating is sufficient to decompose 0.1 g refractory ore sample. An excellent microwave digestion solid agent should meet the following conditions, a good decomposition ability, an outstanding ability of absorbing microwave energy and converting it into heat quickly, a higher melting point than the decomposing temperature of the ore sample. In the research, the induction effect of water plays an important role for the microwave digestion. The energy which is released by the reaction of water and the solid fusion agent (Na 2 O 2 ) is the key to decompose refractory ore samples with solid fusion agent, which replenished the total energy required for the microwave digestion and made the microwave digestion completed successfully. This microwave digestion technique has good reproducibility and precision, RSD % for Mo, Fe, Ti, Cr and W in the refractory ore samples were all better than 6, except RSD % for Be of about 8 because of the influence of matrix-effect. Meanwhile, the analysis results of the elements in the refractory ore samples provided by the microwave digestion technique were all in good agreement with the analysis results provided by the traditional fusion method except for Cr in the mixture ore samples. In the study, the non-linear dependence of the electromagnetic and thermal properties of the solid fusion agent on temperature under microwave irradiation and the selective heating of microwave are fully applied in this simple microwave technique. Comparing to the traditional fusion decomposition method, this microwave digestion technique is a simple, economical, fast and energy-saving sample pre-treatment technique. Copyright © 2018 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.

Application of methyl silane coated iron oxide magnetic nanoparticles for solid-phase extraction and determination of fat-soluble vitamins by high performance liquid chromatography.

PubMed

Momenbeik, Fariborz; Yazdani, Elham

2015-01-01

Methyl silane coated Fe3O4 magnetic nanoparticles were used for simultaneous extraction of the fat-soluble vitamins (FSVs). The amounts of extracted vitamins were determined by HPLC. The synthesized Fe3O4 nanoparticles were coated with silica and then modified with trimethoxymethylsilane (TMMS). The prepared particles were characterized by different methods. The best amounts of silica and TMMS in sorbent synthesis were 1.2 and 0.5 mL, respectively. The optimum pH values for the sample solution and washing buffer were 5 and 3, respectively. Application of 100 mg sorbent, 700 μL tetrahydrofuran, 5-fold dilution of the sample solution, and 1 min for sorption and desorption times were among the best conditions. At the optimum conditions, the calibration plots for each vitamin were obtained with good linearity (R(2) >0.9992) and suitable linear ranges. This method has a low LOD (<76.1 μg/mL), acceptable repeatability (RSD <5.63%) and reproducibility (RSD <4.71%), and good accuracy (recovery >90.3%). Preconcentration of low concentrations of vitamin D3 was performed, and results showed 3.7 times greater sensitivity after preconcentration. Finally, the amounts of the FSVs in pharmaceutical formulations were determined using the proposed method, and results showed good agreement with those reported by manufacturers.

Determination of ammonium in wastewaters by capillary electrophoresis on a column-coupling chip with conductivity detection.

PubMed

Luc, Milan; Kruk, Pavol; Masár, Marián

2011-07-01

Analytical potentialities of a chip-based CE in determination of ammonium in wastewaters were investigated. CZE with the electric field and/or ITP sample stacking was performed on a column-coupling (CC) chip with integrated conductivity detectors. Acetate background electrolytes (pH ∼3) including 18-crown-6-ether (18-crown-6) and tartaric acid were developed to reach rapid (in 7-8 min) CZE and ITP-CZE resolutions of ammonium from other cations (sodium, potassium, calcium and magnesium) present in wastewater samples. Under preferred working conditions (suppressed hydrodynamic flow (HDF) and EOF on the column-coupling chip), both the employed methods did provide very good repeatabilities of the migration (RSD of 0.2-0.8% for the migration time) and quantitative (RSD of 0.3-4.9% for the peak area) parameters in the model and wastewater samples. Using a 900-nL sample injection volume, LOD for ammonium were obtained at 20 and 40 μg/L concentrations in CZE and ITP-CZE separations, respectively. Very good agreements of the CZE and ITP-CZE determinations of ammonium in six untreated wastewater samples (only filtration and dilution) with the results obtained by a reference spectrometric method indicate a very good accuracy of both the CE methods presented. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

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.

Performance of optical biosensor using alcohol oxidase enzyme for formaldehyde detection

NASA Astrophysics Data System (ADS)

Sari, A. P.; Rachim, A.; Nurlely, Fauzia, V.

2017-07-01

The recent issue in the world is the long exposure of formaldehyde which is can increase the risk of human health, therefore, that is very important to develop a device and method that can be optimized to detect the formaldehyde elements accurately, have a long lifetime and can be fabricated and produced in large quantities. A new and simple prepared optical biosensor for detection of formaldehyde in aqueous solutions using alcohol oxidase (AOX) enzyme was successfully fabricated. The poly-n-butyl acrylic-co-N-acryloxysuccinimide (nBA-NAS) membranes containing chromoionophore ETH5294 were used for immobilization of alcohol oxidase enzyme (AOX). Biosensor response was based on the colour change of chromoionophore as a result of enzymatic oxidation of formaldehyde and correlated with the detection concentration of formaldehyde. The performance of biosensor parameters were measured through the optical absorption value using UV-Vis spectrophotometer including the repeatability, reproducibility, selectivity and lifetime. The results showed that the prepared biosensor has good repeatability (RSD = 1.9 %) and good reproducibility (RSD = 2.1 %). The biosensor was selective formaldehyde with no disturbance by methanol, ethanol, and acetaldehyde, and also stable before 49 days and decrease by 41.77 % after 49 days.

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

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

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.

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 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.

Atmospheric pressure gas chromatography quadrupole-time-of-flight mass spectrometry for simultaneous determination of fifteen organochlorine pesticides in soil and water.

PubMed

Cheng, Zhipeng; Dong, Fengshou; Xu, Jun; Liu, Xingang; Wu, Xiaohu; Chen, Zenglong; Pan, Xinglu; Zheng, Yongquan

2016-02-26

In this study, the application of atmospheric pressure gas chromatography quadrupole-time-of-flight mass spectrometry (APGC-QTOF-MS) has been investigated for simultaneous determination of fifteen organochlorine pesticides in soil and water. Soft ionization of atmospheric pressure gas chromatography was evaluated by comparing with traditional more energetic electron impact ionization (EI). APGC-QTOF-MS showed a sensitivity enhancement by approximately 7-305 times. The QuEChERs (Quick, Easy, Cheap, Effective, Rugged, and Safe) method was used to pretreat the soil samples and solid phase extraction (SPE) cleanup was used for water samples. Precision, accuracy and stability experiments were undertaken to evaluate the feasibility of the method. The results showed that the mean recoveries for all the pesticides from the soil samples were 70.3-118.9% with 0.4-18.3% intra-day relative standard deviations (RSD) and 1.0-15.6% inter-day RSD at 10, 50 and 500 μg/L levels, while the mean recoveries of water samples were 70.0-118.0% with 1.1-17.8% intra-day RSD and 0.5-12.2% inter-day RSD at 0.1, 0.5 and 1.0 μg/L levels. Excellent linearity (0.9931 ≦ r(2)≤ 0.9999) was obtained for each pesticides in the soil and water matrix calibration curves within the range of 0.01-1.0mg/L. The limits of detection (LOD) for each of the 15 pesticides was less than 3.00 μg/L, while the limit of quantification (LOQ) was less than 9.99 μg/L in soil and water. Furthermore, the developed method was successfully applied to monitor the targeted pesticides in real soil and water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Storage stability study of porcine hepatic and intestinal cytochrome P450 isoenzymes by use of a newly developed and fully validated highly sensitive HPLC-MS/MS method.

PubMed

Schelstraete, Wim; Devreese, Mathias; Croubels, Siska

2018-02-01

Microsomes are an ideal medium to investigate cytochrome P450 (CYP450) enzyme-mediated drug metabolism. However, before microsomes are prepared, tissues can be stored for a long time. Studies about the stability of these enzymes in porcine hepatic and intestinal tissues upon storage are lacking. To be able to investigate CYP450 stability in microsomes prepared from these tissues, a highly sensitive and rapid HPLC-MS/MS method for the simultaneous determination of six CYP450 metabolites in incubation medium was developed and validated. The metabolites, paracetamol (CYP1A), 7-hydroxy-coumarin (CYP2A), 1-hydroxy-midazolam (CYP3A), 4-hydroxy-tolbutamide (CYP2C), dextrorphan (CYP2D), and 6-hydroxy-chlorzoxazone (CYP2E) were extracted with ethyl acetate at pH 1.0, followed by evaporation and separation on an Agilent Zorbax Eclipse Plus C18 column. The method was fully validated in a GLP-compliant laboratory according to European guidelines and was highly sensitive (LOQ = 0.25-2.5 ng/mL), selective, had good precision (RSD-within, 1.0-9.1%; RSD-between, 1.0-18.4%) and accuracy (within-run, 83.3-102%; between-run, 78.5-102%), and showed no relative signal suppression and enhancement. Consequently, this method was applied to study the stability of porcine hepatic and intestinal CYP450 isoenzymes when tissues were stored at - 80 °C. The results indicate that porcine CYP450 isoenzymes are stable in tissues at least up to 4 months when snap frozen and stored at - 80 °C. Moreover, the results indicate differences in porcine CYP450 stability compared to rat, rabbit, and fish CYP450, as observed by other research groups, hence stressing the importance to investigate the CYP450 stability of a specific species.

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

Properties of low power spark ablation in aqueous solution for dissolution of precious metals and alloys

NASA Astrophysics Data System (ADS)

Goltz, Douglas; Boileau, Michael; Plews, Ian; Charleton, Kimberly; Hinds, Michael W.

2006-07-01

Spark ablation or electric dispersion of metal samples in aqueous solution can be a useful approach for sample preparation. The ablated metal forms a stable suspension that has been described as colloidal, which is easily dissolved with a small amount of concentrated (16 M) HNO 3. In this study, we have examined some of the properties of the spark ablation process for a variety of metals (Rh and Au) and alloys (stainless steel) using a low power spark (100-300 W). Particle size distributions and conductivity measurements were carried out on selected metals to characterize the stable suspensions. A LASER diffraction particle size analyzer was useful for showing that ablated particles varied in size from 1 to 30 μm for both the silver and the nickel alloy, Inconel. In terms of weight percent most of the particles were between 10 and 30 μm. Conductivity of the spark ablation solution was found to increase linearly for approximately 3 min before leveling off at approximately 300 S cm 3. These measurements suggest that a significant portion of the ablated metal is also ionic in nature. Scanning electron microscope measurements revealed that a low power spark is much less damaging to the metal surface than a high power spark. Crater formation of the low power spark was found in a wider area than expected with the highest concentration where the spark was directed. The feasibility of using spark ablation for metal dissolution of a valuable artifact such as gold was also performed. Determinations of Ag (4-12%) and Cu (1-3%) in Bullion Reference Material (BRM) gave results that were in very good agreement with the certified values. The precision was ± 0.27% for Ag at 4.15% (RSD = 6.5%) and ± 0.09% for Cu at 1% (RSD = 9.0%).

Triple quadrupole tandem mass spectrometry: A real alternative to high resolution magnetic sector instrument for the analysis of polychlorinated dibenzo-p-dioxins, furans and dioxin-like polychlorinated biphenyls.

PubMed

García-Bermejo, Ángel; Ábalos, Manuela; Sauló, Jordi; Abad, Esteban; González, María José; Gómara, Belén

2015-08-19

This paper reports on the optimisation, characterisation, validation and applicability of gas chromatography coupled to triple quadrupole mass spectrometry in its tandem operation mode (GC-QqQ(MS/MS) for the quantification of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs, dioxins) and dioxin-like polychlorinated biphenyls (DL-PCBs) in environmental and food matrices. MS/MS parameters were selected to achieve the high sensitivity and selectivity required for the analysis of this type of compounds and samples. Good repeatability for areas (RSD = 1-10%, for PCDD/Fs and DL-PCBs) and for ion transition ratios (RSD = 0.3-10%, for PCDD/Fs, and 0.2-15%, for DL-PCBs) and low instrumental limits of detection, 0.07-0.75 pg μL(-1) (for dioxins) and 0.05-0.63 pg μL(-1) (for DL-PCBs), were obtained. A comparative study of the congener specific determination using both GC-QqQ(MS/MS) and gas chromatography-high resolution mass spectrometry (GC-HRMS) was also performed by analysing several fortified samples and certified reference materials (CRMs) with low (feed and foodstuffs), median (sewage sludge) and high (fly ash) toxic equivalency (TEQ) concentration levels, i.e. 0.60, 1.83, 72.9 and 3609 pg WHO-TEQ(PCDD/Fs) g(-1). The agreement between the results obtained for the total TEQs (dioxins) on GC-QqQ(MS/MS) and GC-HRMS in all the investigated samples were within the range of ±4%, and that of DL-PCBs at concentration levels of 0.84 pg WHO-TEQs (DL-PCBs) g(-1), in the case of feedstuffs, was 0.11%. Both instrumental methods have similar and comparable linearity, precision and accuracy. The GC-QqQ(MS/MS) sensitivity, lower than that of GC-HRMS, is good enough (iLODs in the down to low pg levels) to detect the normal concentrations of these compounds in food and environmental samples. These results make GC-QqQ(MS/MS) suitable for the quantitative analysis of dioxins and DL-PCBs and a real alternative tool to the reference sector HRMS instruments. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparative study of different alcohol sensors based on Screen-Printed Carbon Electrodes.

PubMed

Costa Rama, Estefanía; Biscay, Julien; González García, María Begoña; Julio Reviejo, A; Pingarrón Carrazón, José Manuel; Costa García, Agustín

2012-05-30

Different very simple single-use alcohol enzyme sensors were developed using alcohol oxidase (AOX) from three different yeast, Hansenula sp., Pichia pastoris and Candida boidinii, and employing three different commercial mediator-based Screen-Printed Carbon Electrodes as transducers. The mediators tested, Prussian Blue, Ferrocyanide and Co-phthalocyanine were included into the ink of the working electrode. The procedure to obtain these sensors consists of the immobilization of the enzyme on the electrode surface by adsorption. For the immobilization, an AOX solution is deposited on the working electrode and left until dried (1h) at room temperature. The best results were obtained with the biosensor using Screen-Printed Co-phthalocyanine/Carbon Electrode and AOX from Hansenula sp. The reduced cobalt-phthalocyanine form is amperometrically detected at +0.4V (vs. Ag pseudo reference electrode). This sensor shows good sensitivity (1211 nA mM(-1)), high precision (2.1% RSD value for the slope value of the calibration plot) and wide linear response (0.05-1.00 mM) for ethanol determination. The sensor provides also accurate results for ethanol quantification in alcoholic drinks. Copyright © 2012 Elsevier B.V. All rights reserved.

Uniform Sampling Table Method and its Applications II--Evaluating the Uniform Sampling by Experiment.

PubMed

Chen, Yibin; Chen, Jiaxi; Chen, Xuan; Wang, Min; Wang, Wei

2015-01-01

A new method of uniform sampling is evaluated in this paper. The items and indexes were adopted to evaluate the rationality of the uniform sampling. The evaluation items included convenience of operation, uniformity of sampling site distribution, and accuracy and precision of measured results. The evaluation indexes included operational complexity, occupation rate of sampling site in a row and column, relative accuracy of pill weight, and relative deviation of pill weight. They were obtained from three kinds of drugs with different shape and size by four kinds of sampling methods. Gray correlation analysis was adopted to make the comprehensive evaluation by comparing it with the standard method. The experimental results showed that the convenience of uniform sampling method was 1 (100%), odds ratio of occupation rate in a row and column was infinity, relative accuracy was 99.50-99.89%, reproducibility RSD was 0.45-0.89%, and weighted incidence degree exceeded the standard method. Hence, the uniform sampling method was easy to operate, and the selected samples were distributed uniformly. The experimental results demonstrated that the uniform sampling method has good accuracy and reproducibility, which can be put into use in drugs analysis.

Sequential injection ionic liquid dispersive liquid-liquid microextraction for thallium preconcentration and determination with flame atomic absorption spectrometry.

PubMed

Anthemidis, Aristidis N; Ioannou, Kallirroy-Ioanna G

2012-08-01

A novel, automatic on-line sequential injection dispersive liquid-liquid microextraction (SI-DLLME) method, based on 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF(6)]) ionic liquid as an extractant solvent was developed and demonstrated for trace thallium determination by flame atomic absorption spectrometry. The ionic liquid was on-line fully dispersed into the aqueous solution in a continuous flow format while the TlBr(4)(-) complex was easily migrated into the fine droplets of the extractant due to the huge contact area of them with the aqueous phase. Furthermore, the extractant was simply retained onto the surface of polyurethane foam packed into a microcolumn. No specific conditions like low temperature are required for extractant isolation. All analytical parameters of the proposed method were investigated and optimized. For 15 mL of sample solution, an enhancement factor of 290, a detection limit of 0.86 μg L(-1) and a precision (RSD) of 2.7% at 20.0 μg L(-1) Tl(I) concentration level, was obtained. The developed method was evaluated by analyzing certified reference materials while good recoveries from environmental and biological samples proved that present method was competitive in practical applications.

A novel approach to the simultaneous extraction and non-targeted analysis of the small molecules metabolome and lipidome using 96-well solid phase extraction plates with column-switching technology.

PubMed

Li, Yubo; Zhang, Zhenzhu; Liu, Xinyu; Li, Aizhu; Hou, Zhiguo; Wang, Yuming; Zhang, Yanjun

2015-08-28

This study combines solid phase extraction (SPE) using 96-well plates with column-switching technology to construct a rapid and high-throughput method for the simultaneous extraction and non-targeted analysis of small molecules metabolome and lipidome based on ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry. This study first investigated the columns and analytical conditions for small molecules metabolome and lipidome, separated by an HSS T3 and BEH C18 columns, respectively. Next, the loading capacity and actuation duration of SPE were further optimized. Subsequently, SPE and column switching were used together to rapidly and comprehensively analyze the biological samples. The experimental results showed that the new analytical procedure had good precision and maintained sample stability (RSD<15%). The method was then satisfactorily applied to more widely analyze the small molecules metabolome and lipidome to test the throughput. The resulting method represents a new analytical approach for biological samples, and a highly useful tool for researches in metabolomics and lipidomics. Copyright © 2015 Elsevier B.V. All rights reserved.

Screen-Printed Carbon Electrodes Modified with Cobalt Phthalocyanine for Selective Sulfur Detection in Cosmetic Products

PubMed Central

Chen, Pei-Yen; Luo, Chin-Hsiang; Chen, Mei-Chin; Tsai, Feng-Jie; Chang, Nai-Fang; Shih, Ying

2011-01-01

Cobalt phthalocyanine (CoPc) films were deposited on the surface of a screen-printed carbon electrode using a simple drop coating method. The cyclic voltammogram of the resulting CoPc modified screen-printed electrode (CoPc/SPE) prepared under optimum conditions shows a well-behaved redox couple due to the (CoI/CoII) system. The CoPc/SPE surface demonstrates excellent electrochemical activity towards the oxidation of sulfur in a 0.01 mol·L−1 NaOH. A linear calibration curve with the detection limit (DL, S/N = 3) of 0.325 mg·L−1 was achieved by CoPc/SPE coupled with flow injection analysis of the sulfur concentration ranging from 4 to 1120 mg·L−1. The precision of the system response was evaluated (3.60% and 3.52% RSD for 12 repeated injections), in the range of 64 and 480 mg·L−1 sulfur. The applicability of the method was successfully demonstrated in a real sample analysis of sulfur in anti-acne creams, and good recovery was obtained. The CoPc/SPE displayed several advantages in sulfur determination including easy fabrication, high stability, and low cost. PMID:21747708

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.

Determination of mercury by multisyringe flow injection system with cold-vapor atomic absorption spectrometry.

PubMed

Leal, L O; Elsholz, O; Forteza, R; Cerdà, V

2006-07-28

A new software-controlled time-based multisyringe flow injection system for mercury determination by cold-vapor atomic absorption spectrometry is proposed. Precise known volumes of sample, reducing agent (1.1% SnCl2 in 3% HCl) and carrier (3% HCl) are dispensed into a gas-liquid separation cell with a multisyringe burette coupled with one three-way solenoid valve. An argon flow delivers the reduced mercury to the spectrometer. The optimization of the system was carried out testing reaction coils and gas-liquid separators of different design as well as changing parameters, such as sample and reagents volumes, reagent concentrations and carrier gas flow rate, among others. The analytical curves were obtained within the range 50-5000 ng L(-1). The detection limit (3sigma(b)/S) achieved is 5 ng L(-1). The relative standard deviation (R.S.D.) was 1.4%, evaluated from 16 successive injections of 250 ng L(-1) Hg standard solution. The injection and sample throughput per hour were 44 and 11, respectively. This technique was validated by means of solid and water reference materials with good agreement with the certified values and was successfully applied to fish samples.

Validated stability-indicating densitometric thin-layer chromatography: application to stress degradation studies of minocycline.

PubMed

Jain, Nilu; Jain, Gaurav Kumar; Ahmad, Farhan Jalees; Khar, Roop Krishen

2007-09-19

A simple, stability-indicating high-performance thin-layer liquid chromatographic (HPTLC) method for analysis of minocycline was developed and validated. The densitometric analysis was carried out at 345 nm using methanol-acetonitrile-isopropyl alcohol-water (5:4:0.5:0.5, v/v/v/v) as mobile phase. The method employed TLC aluminium plates pre-coated with silica gel 60F-254 as the stationary phase. To achieve good result, plates were sprayed with a 10% (w/v) solution of disodium ethylene diaminetetraacetic acid (EDTA), the pH of which was adjusted to 9.0. Compact spots of minocycline were found at R(f) = 0.30+/-0.02. For proposed procedure, linearity (r = 0.9997), limit of detection (3.7 ng spot(-1)), recovery (99.23-100.16%), and precision (% R.S.D. < or = 0.364) was found to be satisfactory. The drug undergoes acidic and basic degradation, oxidation and photodegradation. All the peaks of degradation products were well resolved from the pure drug with significantly different R(f) values. The acidic and alkaline degradation kinetics of minocycline, evaluated using this method, is found to be of first order.

Simultaneous microemulsion liquid chromatographic analysis of fat-soluble vitamins in pharmaceutical formulations: optimization using genetic algorithm.

PubMed

Momenbeik, Fariborz; Roosta, Mostafa; Nikoukar, Ali Akbar

2010-06-11

An environmentally benign and simple method has been proposed for separation and determination of fat-soluble vitamins using isocratic microemulsion liquid chromatography. Optimization of parameters affecting the separation selectivity and efficiency including surfactant concentration, percent of cosurfactant (1-butanol), and percent of organic oily solvent (diethyl ether), temperature and pH were performed simultaneously using genetic algorithm method. A new software package, MLR-GA, was developed for this purpose. The results indicated that 73.6mM sodium dodecyl sulfate, 13.64% (v/v) 1-butanol, 0.48% (v/v) diethyl ether, column temperature of 32.5 degrees C and 0.02M phosphate buffer of pH 6.99 are the best conditions for separation of fat-soluble vitamins. At the optimized conditions, the calibration plots for the vitamins were obtained and detection limits (1.06-3.69microgmL(-1)), accuracy (recoveries>94.3), precision (RSD<3.96) and linearity (0.01-10mgmL(-1)) were estimated. Finally, the amount of vitamins in multivitamin syrup and a sample of fish oil capsule were determined. The results showed a good agreement with those reported by manufactures. Copyright 2010 Elsevier B.V. All rights reserved.

On-line MSPD-SPE-HPLC/FLD analysis of polycyclic aromatic hydrocarbons in bovine tissues.

PubMed

Gutiérrez-Valencia, Tania M; García de Llasera, Martha P

2017-05-15

A fast method was optimized and validated for simultaneous trace determination of four polycyclic aromatic hydrocarbons: benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene and benzo[a]pyrene in bovine tissues. The determination was performed by matrix solid-phase dispersion (MSPD) coupled on-line to solid phase extraction (SPE) and high performance liquid chromatography (HPLC) with fluorescence detection (FLD). The sample was dispersed on C 18 silica sorbent and then the on-line MSPD-SPE-HPLC/FLD method was applied. Several parameters were optimized: cleaning and elution sequences applied to the MSPD cartridge, the flow rate and dilution of extract used for SPE loading. The on-line method was validated over a concentration range of 0.1-0.6ngg -1 obtaining good linearity (r⩾0.998) and precision (RSD)⩽10%. Recovery ranged from 96 to 99% and the limits of detection were 0.012ngg -1 . This methodology was applied to liver samples from unhealthy animals. The results demonstrate that MSDP-SPE-HPLC/FLD method provides reliable, sensitive, accurate and fast data to the food control. Copyright © 2016 Elsevier Ltd. 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.

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.

Indirect spectrophotometric determination of arbutin, whitening agent through oxidation by periodate and complexation with ferric chloride

NASA Astrophysics Data System (ADS)

Barsoom, B. N.; Abdelsamad, A. M. E.; Adib, N. M.

2006-07-01

A simple and accurate spectrophotometric method for the determination of arbutin (glycosylated hydroquinone) is described. It is based on the oxidation of arbutin by periodate in presence of iodate. Excess periodate causes liberation of iodine at pH 8.0. The unreacted periodate is determined by measurement of the liberated iodine spectrophotometrically in the wavelength range (300-500 nm). A calibration curve was constructed for more accurate results and the correlation coefficient of linear regression analysis was -0.9778. The precision of this method was better than 6.17% R.S.D. ( n = 3). Regression analysis of Bear-Lambert plot shows good correlation in the concentration range 25-125 ug/ml. The identification limit was determined to be 25 ug/ml a detailed study of the reaction conditions was carried out, including effect of changing pH, time, temperature and volume of periodate. Analyzing pure and authentic samples containing arbutin tested the validity of the proposed method which has an average percent recovery of 100.86%. An alternative method is also proposed which involves a complexation reaction between arbutin and ferric chloride solution. The produced complex which is yellowish-green in color was determined spectophotometrically.

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.

A multilayer membrane amperometric glucose sensor fabricated using planar techniques for large-scale production.

PubMed

Matsumoto, T; Saito, S; Ikeda, S

2006-03-23

This paper reports on a multilayer membrane amperometric glucose sensor fabricated using planar techniques. It is characterized by good reproducibility and suitable for large-scale production. The glucose sensor has 82 electrode sets formed on a single glass substrate, each with a platinum working electrode (WE), a platinum counter electrode (CE) and an Ag/AgCl reference electrode (RE). The electrode sets are coated with a membrane consisting of five layers: gamma-aminopropyltriethoxysilane (gamma-APTES), Nafion, glucose oxidase (GOX), gamma-APTES and perfluorocarbon polymer (PFCP), in that order. Tests have shown that the sensor has acceptably low dispersion (relative standard deviation, R.S.D.=42.9%, n=82), a wide measurement range (1.11-111 mM) and measurement stability over a 27-day period. Measurements of the glucose concentration in a control human urine sample demonstrated that the sensor has very low dispersion (R.S.D.=2.49%, n=10).

Shuttle data book: SRM fragment velocity model. Presented to the SRB Fragment Model Review Panel

NASA Technical Reports Server (NTRS)

1989-01-01

This study was undertaken to determine the velocity of fragments generated by the range safety destruction (RSD) or random failure of a Space Transportation System (STS) Solid Rocket Motor (SRM). The specific requirement was to provide a fragment model for use in those Galileo and Ulysses RTG safety analyses concerned with possible fragment impact on the spacecraft radioisotope thermoelectric generators (RTGS). Good agreement was obtained between predictions and observations for fragment velocity, velocity distributions, azimuths, and rotation rates. Based on this agreement with the entire data base, the model was used to predict the probable fragment environments which would occur in the event of an STS-SRM RSD or randon failure at 10, 74, 84 and 110 seconds. The results of these predictions are the basis of the fragment environments presented in the Shuttle Data Book (NSTS-08116). The information presented here is in viewgraph form.

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.

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.

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.

Analysis of volatile thiols in alcoholic beverages by simultaneous derivatization/extraction and liquid chromatography-high resolution mass spectrometry.

PubMed

Vichi, Stefania; Cortés-Francisco, Nuria; Caixach, Josep

2015-05-15

A simultaneous derivatization/extraction method followed by liquid chromatography-electrospray-high resolution mass spectrometry for the determination of volatile thiols in hydroalcoholic matrixes was optimized and used to identify and quantify volatile thiols in wine and beer samples. The method was evaluated in terms of sensitivity, precision, accuracy and selectivity. The experimental LOQs of eleven thiols tested ranged between 0.01 ng/L and 10 ng/L. Intra-day relative standard deviation (RSD) was in general lower than 10% and inter-day RSD ranged between 10% and 30%. Recovery in the model and real matrixes ranged from 45% to 129%. The method was then applied for the analysis of four white wines and six beers. Five out of the eleven reference thiols were identified and quantified in the samples analyzed. The non-target approach, carried out by monitoring the diagnostic ion at m/z 275.9922 [C13H10ONSe](+) in the fragmentation spectrum, allowed detecting, in the same samples, fourteen non-target thiols. Copyright © 2014 Elsevier Ltd. All rights reserved.

Validation of a mass spectrometry-based method for milk traces detection in baked food.

PubMed

Lamberti, Cristina; Cristina, Lamberti; Acquadro, Elena; Elena, Acquadro; Corpillo, Davide; Davide, Corpillo; Giribaldi, Marzia; Marzia, Giribaldi; Decastelli, Lucia; Lucia, Decastelli; Garino, Cristiano; Cristiano, Garino; Arlorio, Marco; Marco, Arlorio; Ricciardi, Carlo; Carlo, Ricciardi; Cavallarin, Laura; Laura, Cavallarin; Giuffrida, Maria Gabriella; Gabriella, Giuffrida Maria

2016-05-15

A simple validated LC-MS/MS-based method was set up to detect milk contamination in bakery products, taking the effects of food processing into account for the evaluation of allergen recovery and quantification. Incurred cookies were prepared at eight levels of milk contamination and were cooked to expose all milk components, including allergenic proteins, to food processing conditions. Remarkable results were obtained in term of sufficiently low LOD and LOQ (1.3 and 4 mg/kg cookies, respectively). Precision was calculated as intra-day repeatability (RSD in the 5-20% range) and inter-day repeatability (4 days; RSD never exceeded 12%). The extraction recovery values ranged from 20% to 26%. Method applicability was evaluated by analysing commercial cookies labelled either as "milk-free" or "may contain milk". Although the ELISA methodology is considered the gold standard for detecting allergens in foods, this robust LC-MS/MS approach should be a useful confirmatory method for assessing and certifying "milk-free" food products. Copyright © 2015 Elsevier Ltd. 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.

Solution-based calibration strategy for laser ablation-inductively coupled plasma-mass spectrometry using desolvating nebulizer system

NASA Astrophysics Data System (ADS)

Zhang, Guoxia; Li, Qing; Zhu, Yan; Wang, Zheng

2018-07-01

An additional quantification strategy using a desolvating nebulizer system (DNS) for solution-based calibration was developed. For quantitative analysis, laser ablation (LA) and DNS-generated aerosols were coupled using a "Y" connector and introduced into the inductively coupled plasma (ICP). These aerosols were also observed by scanning electron microscopy following collection on a silicon chip. Internal standards (108Ag, 64Cu, 89Y) were used to correct for the different aerosol transport efficiencies between the DNS and LA. The correlation coefficients of the calibration curves for all elements ranged from 0.9986 to 0.9999. Standard reference materials (NIST 610-616 and GBW08407-08411) were used to demonstrate the accuracy and precision of the method. The results were in good agreement with certified values, and the relative standard deviation (RSD) of most elements was <3%. The limits of detection (LODs) for 50Cr, 55Mn, 59Co, 60Ni, 66Zn, 89Y, 110Cd, 139La, 140Ce, 146Nd, 147Sm, 157Gd, 163Dy, 166Er, and 208Pb were 23, 3, 3, 19, 31, 4, 12, 0.4, 0.9, 0.1, 0.2, 2, 0.3, 0.4, and 21 ng/g, respectively, which were significantly better than those obtained by other methods. Further, this approach was applied for the analysis of multiple elements in biological tissues, and the results were in good agreement with those obtained using solution-based inductively coupled plasma-mass spectrometry (ICP-MS).

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

Development of a bar adsorptive micro-extraction-large-volume injection-gas chromatography-mass spectrometric method for pharmaceuticals and personal care products in environmental water matrices.

PubMed

Neng, N R; Nogueira, J M F

2012-01-01

The combination of bar adsorptive micro-extraction using activated carbon (AC) and polystyrene-divinylbenzene copolymer (PS-DVB) sorbent phases, followed by liquid desorption and large-volume injection gas chromatography coupled to mass spectrometry, under selected ion monitoring mode acquisition, was developed for the first time to monitor pharmaceutical and personal care products (PPCPs) in environmental water matrices. Assays performed on 25 mL water samples spiked (100 ng L(-1)) with caffeine, gemfibrozil, triclosan, propranolol, carbamazepine and diazepam, selected as model compounds, yielded recoveries ranging from 74% to 99% under optimised experimental conditions (equilibrium time, 16 h (1,000 rpm); matrix characteristics: pH 5, 5% NaCl for AC phase; LD: methanol/acetonitrile (1:1), 45 min). The analytical performance showed good precision (RSD < 18%), convenient detection limits (5-20 ng L(-1)) and excellent linear dynamic range (20-800 ng L(-1)) with remarkable determination coefficients (r(2) > 0.99), where the PS-DVB sorbent phase showed a much better efficiency. By using the standard addition methodology, the application of the present analytical approach on tap, ground, sea, estuary and wastewater samples allowed very good performance at the trace level. The proposed method proved to be a suitable sorption-based micro-extraction alternative for the analysis of priority pollutants with medium-polar to polar characteristics, showing to be easy to implement, reliable, sensitive and requiring a low sample volume to monitor PPCPs in water matrices.

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.

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.

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.

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.

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

Determination of N,N-dimethyltryptamine in beverages consumed in religious practices by headspace solid-phase microextraction followed by gas chromatography ion trap mass spectrometry.

PubMed

Gaujac, Alain; Dempster, Nicola; Navickiene, Sandro; Brandt, Simon D; de Andrade, Jailson Bittencourt

2013-03-15

A novel analytical approach combining solid-phase microextraction (SPME)/gas chromatography ion trap mass spectrometry (GC-IT-MS) was developed for the detection and quantification N,N-dimethyltryptamine (DMT), a powerful psychoactive indole alkaloid present in a variety of South American indigenous beverages, such as ayahuasca and vinho da jurema. These particular plant products, often used within a religious context, are increasingly consumed throughout the world following an expansion of religious groups and the availability of plant material over the Internet and high street shops. The method described in the present study included the use of SPME in headspace mode combined GC-IT-MS and included the optimization of the SPME procedure using multivariate techniques. The method was performed with a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber in headspace mode (70 min at 60 °C) which resulted in good precision (RSD<8.6%) and accuracy values (71-109%). Detection and quantification limits obtained for DMT were 0.78 and 9.5 mg L(-1), respectively and good linearity (1.56-300 mg L(-1), r(2)=0.9975) was also observed. In addition, the proposed method showed good robustness and allowed for the minimization of sample manipulation. Five jurema beverage samples were prepared in the laboratory in order to study the impact of temperature, pH and ethanol on the ability to extract DMT into solution. The developed method was then applied to the analysis of twelve real ayahuasca and vinho da jurema samples, obtained from Brazilian religious groups, which revealed DMT concentration levels between 0.10 and 1.81 g L(-1). Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis of anthocyanins in commercial fruit juices by using nano-liquid chromatography-electrospray-mass spectrometry and high-performance liquid chromatography with UV-vis detector.

PubMed

Fanali, Chiara; Dugo, Laura; D'Orazio, Giovanni; Lirangi, Melania; Dachà, Marina; Dugo, Paola; Mondello, Luigi

2011-01-01

Nano-LC and conventional HPLC techniques were applied for the analysis of anthocyanins present in commercial fruit juices using a capillary column of 100 μm id and a 2.1 mm id narrow-bore C(18) column. Analytes were detected by UV-Vis at 518 nm and ESI-ion trap MS with HPLC and nano-LC, respectively. Commercial blueberry juice (14 anthocyanins detected) was used to optimize chromatographic separation of analytes and other analysis parameters. Qualitative identification of anthocyanins was performed by comparing the recorded mass spectral data with those of published papers. The use of the same mobile phase composition in both techniques revealed that the miniaturized method exhibited shorter analysis time and higher sensitivity than narrow-bore chromatography. Good intra-day and day-to-day precision of retention time was obtained in both methods with values of RSD less than 3.4 and 0.8% for nano-LC and HPLC, respectively. Quantitative analysis was performed by external standard curve calibration of cyanidin-3-O-glucoside standard. Calibration curves were linear in the concentration ranges studied, 0.1-50 and 6-50 μg/mL for HPLC-UV/Vis and nano-LC-MS, respectively. LOD and LOQ values were good for both methods. In addition to commercial blueberry juice, qualitative and quantitative analysis of other juices (e.g. raspberry, sweet cherry and pomegranate) was performed. The optimized nano-LC-MS method allowed an easy and selective identification and quantification of anthocyanins in commercial fruit juices; it offered good results, shorter analysis time and reduced mobile phase volume with respect to narrow-bore HPLC. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preconcentration of β-blockers using functionalized ordered mesoporous silica as sorbent for SPE and their determination in waters by chiral CE.

PubMed

Silva, Mariana; Morante-Zarcero, Sonia; Pérez-Quintanilla, Damián; Marina, María Luisa; Sierra, Isabel

2017-08-01

A method for simultaneous separation and determination of four enantiomeric pairs of β-blockers in waters by chiral CE has been developed. Off-line SPE was employed using functionalized ordered mesoporous silica as sorbent. Separation by CE was achieved using a BGE composed by methylated-β-CD (1.25% w/v) dissolved in a 50 mM phosphate buffer (pH 2.5) and 30°C, with good chiral resolution for all enantiomers. Mesoporous silica functionalized with octadecyl groups (denoted SBA15-C18) was prepared by a postsynthesis method and applied for the preconcentration of atenolol, propranolol, metoprolol, and pindolol enantiomers in waters by off-line SPE. Under optimized conditions, a preconcentration factor of 300 was achieved, employing 100 mg of SBA15-C18 as sorbent, with recoveries between 96 and 105% in tap water and good repeatability (% RSD = 7-11%, n = 6). Commercial C18 amorphous silica (ExtraBond R C 18 ) was also tested as sorbent for SPE, but results revealed better extraction capacity with higher recoveries for the SBA15-C18 material. The analytical characteristics of the off-line SPE-chiral CE method were evaluated, showing good precision, linearity, and accuracy with method quantification limits between 5.3 and 13.7 μg/L for all enantiomers. The SBA15-C18 material allowed the extraction of four enantiomeric pairs of β-blockers spiked in tap water, river water, and ground water with recoveries between 58 and 105%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

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.

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.

Extension of the validation of AOAC Official Method 2005.06 for dc-GTX2,3: interlaboratory study.

PubMed

Ben-Gigirey, Begoña; Rodríguez-Velasco, María L; Gago-Martínez, Ana

2012-01-01

AOAC Official Method(SM) 2005.06 for the determination of saxitoxin (STX)-group toxins in shellfish by LC with fluorescence detection with precolumn oxidation was previously validated and adopted First Action following a collaborative study. However, the method was not validated for all key STX-group toxins, and procedures to quantify some of them were not provided. With more STX-group toxin standards commercially available and modifications to procedures, it was possible to overcome some of these difficulties. The European Union Reference Laboratory for Marine Biotoxins conducted an interlaboratory exercise to extend AOAC Official Method 2005.06 validation for dc-GTX2,3 and to compile precision data for several STX-group toxins. This paper reports the study design and the results obtained. The performance characteristics for dc-GTX2,3 (intralaboratory and interlaboratory precision, recovery, and theoretical quantification limit) were evaluated. The mean recoveries obtained for dc-GTX2,3 were, in general, low (53.1-58.6%). The RSD for reproducibility (RSD(r)%) for dc-GTX2,3 in all samples ranged from 28.2 to 45.7%, and HorRat values ranged from 1.5 to 2.8. The article also describes a hydrolysis protocol to convert GTX6 to NEO, which has been proven to be useful for the quantification of GTX6 while the GTX6 standard is not available. The performance of the participant laboratories in the application of this method was compared with that obtained from the original collaborative study of the method. Intralaboratory and interlaboratory precision data for several STX-group toxins, including dc-NEO and GTX6, are reported here. This study can be useful for those laboratories determining STX-group toxins to fully implement AOAC Official Method 2005.06 for official paralytic shellfish poisoning control. However the overall quantitative performance obtained with the method was poor for certain toxins.

Efficacy and Safety of Renal Sympathetic Denervation on Dogs with Pressure Overload-Induced Heart Failure.

PubMed

Chen, Pingan; Leng, Shuilong; Luo, Yishan; Li, Shaonan; Huang, Zicheng; Liu, Zhenxi; Liu, Zhen; Wang, Jie; Lei, Xiaoming

2017-02-01

In dogs with heart failure (HF) induced by overload pressure, the role of renal sympathetic denervation (RSD) on heart failure and in the renal artery is unclear. Therefore, we investigated the efficacy and safety of RSD in dogs with pressure overload-induced heart failure. Twenty mongrel dogs were divided into a sham-operated group, an HF group and an HF + RSD group. In the sham-operated group, the abdominal aorta was located but was not constricted, in the HF group, the abdominal aorta was constricted without RSD, and the HF+RSD group underwent RSD with constriction of the abdominal aorta after 10 weeks. Blood sampling assays, echocardiography, intravascular ultrasound (IVUS) measurement and histopathological examination were performed. Renal sympathetic denervation caused a significant reduction in the levels of noradrenaline (166.62±6.84 vs. 183.48±13.66 pg/ml, P<0.05), plasma renin activity (1.93±0.12 vs. 2.10±0.13 ng/mlh, P<0.05) and B-type natriuretic peptide (71.14±3.86 vs. 83.15±5.73 pg/ml, P<0.05) at eight weeks after RSD in the HF+RSD group. Compared with the HF group at eight weeks, the left ventricular internal dimension at end-diastole and end-systole were lower and the left ventricular ejection fraction was higher (all P<0.05) at eight weeks after RSD in the HF+RSD group. Intravenous ultrasound images showed no changes in the renal artery lumen, and intimal hyperplasia and vascular lumen stenosis were not observed after RSD. Renal sympathetic denervation could improve cardiac function in dogs with HF induced by pressure overload; RSD had no adverse influence on the renal artery. Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Development of a Smartphone-based reading system for lateral flow immunoassay.

PubMed

Lee, Sangdae; Kim, Giyoung; Moon, Jihea

2014-11-01

This study was conducted to develop and evaluate the performance of the Smartphone-based reading system for the lateral flow immunoassay (LFIA). Smartphone-based reading system consists of a Samsung Galaxy S2 Smartphone, Smartphone application, and a LFIA reader. LFIA reader is composed of the close-up lens with a focal length up to 30 mm, white LED light, lithium polymer battery, and main body. The Smartphone application for image acquisition and data analysis was developed on the Android platform. The standard curve was obtained by plotting the measured P(T)/P(c) or A(T)/A(c) ratio versus Salmonella standard concentration. The mean, standard deviation (SD), recovery, and relative standard deviation (RSD) were also calculated using additional experimental results. These data were compared with that obtained from the benchtop LFIA reader. The LOD in both systems was observed with 10(6) CFU/mL. The results show high accuracy and good reproducibility with a RSD less than 10% in the range of 10(6) to 10(9) CFU/mL. Due to the simple structure, good sensitivity, and high accuracy of the Smartphone-based reading system, this system can be substituted for the benchtop LFIA reader for point-of-care medical diagnostics.

Non-enzymatic glucose sensor based on electrodeposited copper on carbon paste electrode (Cu/CPE)

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

Nurani, Dita Arifa, E-mail: d.arifa@sci.ui.ac.id; Wibowo, Rahmat; Fajri, Iqbal Farhan El

The development of non-enzymatic glucose sensor has much attention due to their applications in glucose monitoring. In this research, copper oxide is used as a non-enzymatic glucose sensor by oxidizing glucose to gluconolactone. Copper was electrodeposited on Carbon paste electrode (CPE) at constant potential. The experimental condition was varied in electrodeposition of Cu with the following parameters: Electrodeposition time 60 s, 120 s and 180 s and potential reduction -0.166 V, -0.266 V and -0.366 V. The effective performance of these working electrodes in sensing glucose was investigated. The Cu/CPE which used -0.366 V potential reduction and 120 s electrodeposition time shows the bestmore » performance. The amperometric response current in concentration range 1.6-62.5 mM of glucose gives the good linearity R{sup 2} = 0.9988, low detection limit 0.6728 mM and high sensitivity 1183.59 µA mM{sup −1}cm{sup −2}. Furthermore this sensor exhibited a good repeatability with %RSD = 1.31% (n=10) and high stability with %RSD = 1.51% (n=5 days). The homogeneity of Cu particles on CPE was investigated by Scanning Electron Microscope (SEM).« less

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.

40 CFR 86.1306-07 - Equipment required and specifications; overview.

Code of Federal Regulations, 2010 CFR

2010-07-01

... alternate and reference averages; these are Asd and Rsd respectively. Asd must be less than or equal to Rsd. If Asd is greater than Rsd, the Administrator will not approve the application. (D) For an unpaired comparison, calculate the t-value: tunpaired = (Aavg−Ravg)/((Asd 2+Rsd 2)/n)1/2 (E) For a paired comparison...

40 CFR 86.1306-07 - Equipment required and specifications; overview.

Code of Federal Regulations, 2013 CFR

2013-07-01

... alternate and reference averages; these are Asd and Rsd respectively. Asd must be less than or equal to Rsd. If Asd is greater than Rsd, the Administrator will not approve the application. (D) For an unpaired comparison, calculate the t-value: tunpaired = (Aavg−Ravg)/((Asd 2+Rsd 2)/n)1/2 (E) For a paired comparison...

40 CFR 86.1306-07 - Equipment required and specifications; overview.

Code of Federal Regulations, 2012 CFR

2012-07-01

... alternate and reference averages; these are Asd and Rsd respectively. Asd must be less than or equal to Rsd. If Asd is greater than Rsd, the Administrator will not approve the application. (D) For an unpaired comparison, calculate the t-value: tunpaired = (Aavg−Ravg)/((Asd 2+Rsd 2)/n)1/2 (E) For a paired comparison...

40 CFR 86.1306-07 - Equipment required and specifications; overview.

Code of Federal Regulations, 2011 CFR

2011-07-01

... alternate and reference averages; these are Asd and Rsd respectively. Asd must be less than or equal to Rsd. If Asd is greater than Rsd, the Administrator will not approve the application. (D) For an unpaired comparison, calculate the t-value: tunpaired = (Aavg−Ravg)/((Asd 2+Rsd 2)/n)1/2 (E) For a paired comparison...

A global view of Escherichia coli Rsd protein and its interactions.

PubMed

Piper, Sarah E; Mitchell, Jennie E; Lee, David J; Busby, Stephen J W

2009-12-01

The Escherichia coli Rsd protein forms 1 : 1 complexes with sigma(70) protein, which is the major factor in determining promoter recognition by RNA polymerase. Here we describe measurements of the levels of Rsd, RNA polymerase, sigma(70) and the alternative sigma(38) factor. Rsd levels are sufficient to sequester a significant proportion of sigma(70) and immunoaffinity pull-down experiments show that this occurs in stationary phase but not in exponentially growing cells. Rsd expression is controlled by two promoters, P1 and P2. Experiments with lac fusions show that the P2 promoter is stronger than P1, that P2 is active in all phases of growth, and that this accounts for the high levels of Rsd.

Vocational rehabilitation considerations for people with reflex sympathetic dystrophy.

PubMed

Smith, T S; Genoff, M C

1997-01-01

Reflex sympathetic dystrophy (RSD) is identified by the existence of pain, trophic changes, vasomotor instability, limited range of motion and swelling of an extremity. RSD is difficult to treat and prognosis is often poor. Although widely noted in the medical literature, the vocational rehabilitation literature has failed to address the potential role of vocational rehabilitation professionals in the social and economic employment outcome for people with RSD. Vocational rehabilitation professionals are defined as those performing vocational assessments, assessing transferable skills, determining adaptive skills, certifying residual work-related capacities, conducting vocational interest testing, coordinating efforts with pre-injury employers to assist in work reentry efforts, or performing other activities to assist in the placement or retraining of individuals with RSD. The sources used for this article include a review of the literature and observations of the authors. A vocational rehabilitation primer is provided. The following topics are addressed: the anatomical and physiological basis of RSD, treatment protocols, difficulties in accurately diagnosing RSD, influence of litigation, job placement considerations and vocational planning. As the vocational rehabilitation counsellor faces a greater number of people either diagnosed with RSD, or exhibiting RSD symptoms, he/she will be challenged to: (1) increase one's knowledge base about the etiology and treatment of RSD; (2) coordinate personal efforts with other professionals; and (3) provide personal counselling to address lifestyle and motivational factors.

Preprocedural Anxiety and Pain Perception Following Root Surface Debridement in Chronic Periodontitis Patients.

PubMed

Naik, Vanaja Krishna; Balasundaram, Aruna; Appukuttan, Devapriya; Nainar, Deepavalli Arumuga; Milward, Michael Robert; Victor, Dhayanand John; Junaid, Mohammed

2018-01-01

The aim of this study was to evaluate and compare preprocedural dental anxiety levels and postprocedural pain perception in chronic periodontitis patients during conventional-staged root surface debridement (RSD) and single-stage RSD. Thirty-seven adult generalized chronic periodontitis patients requiring RSD were recruited in this study. Preprocedural anxiety levels were assessed using a self-reported questionnaire and postprocedural pain perceptions were assessed using 0-10 cm visual analog scale. The subject population was divided into two groups: staged RSD ( n = 18) and single-stage RSD ( n = 19). Staged RSD patients visited four times as opposed to single-stage RSD patients. Data were subjected to Pearson Chi-square test, Mann-Whitney U-test, and Spearman's rank correlation. There was no statistically significant difference in dental anxiety levels or pain perceptions in both the groups. Within Group 1, there was statistical significant difference in dental anxiety levels between visit 4 and visit 3 ( P = 0.037) and pain perception between visit 3 and visit 1 ( P = 0.005), visit 4 and visit 1 ( P = 0.002), and visit 4 and visit 2 (0.04) was statistically significant. There was a positive correlation of anxiety questionnaire (Q1-Q4) to the pain score in Group 1 which was statistically significant and in single-stage RSD. Conventional quadrant-wise RSD tends to cognitively condition the anxiety experience thus influencing pain experience.

Formulation of an aloe-based product according to Iranian traditional medicine and development of its analysis method.

PubMed

Moein, Elham; Hajimehdipoor, Homa; Toliyat, Tayebeh; Choopani, Rasool; Hamzeloo-Moghadam, Maryam

2017-08-29

Currently, people are more interested to traditional medicine. The traditional formulations should be converted to modern drug delivery systems to be more acceptable for the patients. In the present investigation, a poly herbal medicine "Ayarij-e-Faiqra" (AF) based on Iranian traditional medicine (ITM) has been formulated and its quality control parameters have been developed. The main ingredients of AF including barks of Cinnamomum zeylanicum Blume and Cinnamomum cassia J. Presl, the rhizomes of Nardostachys jatamansi DC., the fruits of Piper cubeba L.f., the flowers of Rosa damascena Herrm., the oleo gum resin of Pistacia terebinthus L. and Aloe spp. dried juice were powdered and used for preparing seven tablet formulations of the herbal mixture. Flowability of the different formulated powders was examined and the best formulations were selected (F6&F7). The tablets were prepared from the selected formulations compared according to the physical characteristics and finally, F7 was selected and coated. Physicochemical characters of core and coated AF tablets were determined and the HPLC method for quantitation of aloin as a marker of tablets was selected and verified according to selectivity, linearity, precision, recovery, LOD and LOQ. The results showed that core and coated AF tablets were in agreement with USP requirements for herbal drugs. They had acceptable appearance, disintegration time, friability, hardness, dissolution behavior, weight variation and content uniformity. The amount of aloin in tablets was found 123.1 mg/tab. The HPLC method for aloin determination in AF tablets was verified according to selectivity, linearity (5-500 μg/ml, r 2 :0.9999), precision (RSD: 1.62%), recovery (108.0%), LOD & LOQ (0.0053 & 0.0161 μg/ml). The formulated tablets could be a good substitute for powder and capsules of AF in ITM clinics with a feasible and precise method for its quality control. Ayarij-e-Faiqra formulation.

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.

Development of Conductivity Method as an Alternative to Titration for Hydrolytic Resistance Testing Used for Evaluation of Glass Vials Used in Pharmaceutical Industry.

PubMed

Fujimori, Kiyoshi; Lee, Hans; Phillips, Joseph; Nashed-Samuel, Yasser

The European Pharmacopeia surface test to analyze the hydrolytic resistance is a common industrial method to understand and ensure the quality of produced glass vials. Hydrolytic resistance is evaluated by calculating the alkalinity of water extract from autoclaved vials by titration. As an alternative to this titration technique, a conductivity technique was assessed, which directly measures the ions in the water extract. A conductivity meter with a 12 mm diameter electrode was calibrated with a 100 μS/cm conductivity standard and carryover minimized by rinsing the probe in a water beaker per analysis. The limit of quantification at 1 μS/cm was determined as having a signal-to-noise ratio of 3 compared with the water blank. The conductivity method was selective for glass-composing elements (boron, sodium, aluminum, silicon, potassium, and calcium) within the vial extract. Accuracies of spiked conductivity standard within the range of 1 to 100 μS/cm were ±7% and had linearity with coefficient of determination (R 2 ) of ≥0.9999. Intraday precision had a relative standard deviation (RSD) (n = 5) of ≤6% for spiked conductivity standard within the range of 1 to 100 μS/cm. Interday precision had a RSD (n = 4) of ≤6% for 10 vials from three glass vial lots. Conductivity of water extracts from nine sets of seven lots of glass vials had a precise linear relationship [R 2 = 0.9876, RSD = 1% (n = 9)] with titration volumes of the same lots. Conductivity results in μS/cm could be converted to titration volumes in milliliters by a conversion factor of 0.0275. The simplicity, sample stability, and individual vial analysis of the conductivity technique were more advantageous than the current titration technique. The quality of glass vials used as primary containers in the pharmaceutical industry is of concern due to recent observations of glass flake-like delamination, or lamellae, under specific storage conditions. The current European Pharmacopoeia method to assess glass vial quality utilizes acid titration of vial extract pools to determine hydrolytic resistance or alkalinity. As an alternative to the European Pharmacopoeia method, the vial extracts were analyzed for conductivity, which directly determines the level of ions that were readily extracted from the vial surfaces. Lower quality glass would have greater surface defects that lead to higher ions extracted and higher conductivity value. The conductivity method was found to be suitable to measure the ions in water extracts and showed strong correlation with alkalinity. The advantage of the conductivity method over the alkalinity method was greater ease, lower volume requirements, stability, and flexibility in analysis. © PDA, Inc. 2017.

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.

Illumina MiSeq investigations on the changes of microbial community in the Fusarium oxysporum f.sp. cubense infected soil during and after reductive soil disinfestation.

PubMed

Huang, Xinqi; Liu, Liangliang; Wen, Teng; Zhu, Rui; Zhang, Jinbo; Cai, Zucong

2015-12-01

Although reductive soil disinfestation (RSD) is increasingly used for the control of soil-borne diseases, its impact on the soil microbial community during and after RSD remains poorly understood. MiSeq pyrosequencing, real-time PCR and denaturing gradient gel electrophoresis were performed to investigate the changes of microbial community in the Fusarium oxysporum f. sp. cubense (FOC) infected soil during RSD and at the simulative banana cultivation after RSD. The results showed that RSD significantly increased soil microbial populations and a different microbial community with the pathogenic soil was established after RSD. Specifically, the number of Firmicutes mainly containing Ruminococcus and Coprococcus followed by a small part of Clostridium which were the dominant bacterial genera significantly increased during RSD. In contrast, Symbiobacterium and Flavisolibacter were the dominant genera in the flooding soil. When the soils were recovered under aerobic condition, the relative abundances of the bacteria belonging to the phylum Bacteroidetes, Acidobacteria, Planctomycetes increased as alternatives to the reducing Firmicutes. For fungi, the population of F. oxysporum significantly decreased during RSD accompanied with the pH decline, which resulted in the significant decrease of relative abundance in the phylum Ascomycota. Alternatively, the relative abundances of some other fungal species increased, such as Chaetomium spp. and Penicillium spp. belonging to Ascomycota and the family Clavulinaceae belonging to Basidiomycota. Then, the relative abundance of Ascomycota re-increased after RSD with Podospora and Zopfiella as dominant genera, whereas the relative abundance of Fusarium further decreased. Overall, the microbial populations and community re-established by RSD made the soil more disease-suppressive and beneficial to the soil nutrient cycling and plant growth compared with the previous pathogenic soil. Copyright © 2015 Elsevier GmbH. All rights reserved.

Effects of renal sympathetic denervation on the atrial electrophysiology in dogs with pacing-induced heart failure.

PubMed

Wang, Xiaozhan; Zhao, Qingyan; Deng, Hongping; Wang, Xule; Guo, Zongwen; Dai, Zixuan; Xiao, Jinping; Wan, Peixing; Huang, Congxin

2014-10-01

Heart failure (HF) and atrial fibrillation (AF) are associated with sympathetic activation. Renal sympathetic denervation (RSD) can suppress AF vulnerability. The impact of RSD on atrial electrophysiology in experimental HF is unclear. Twenty-two beagles were randomized into control, HF, and HF + RSD groups. Control dogs were implanted cardiac pacemakers without pacing. Dogs in the HF group underwent right ventricular pacing for 3 weeks at 240 beats/min to induce HF. The dogs in the HF + RSD group received RSD and underwent the same HF-inducing procedure. The P-wave dispersion was higher in HF dogs than in the control and HF + RSD dogs (19 ± 3.1 ms vs 13 ± 2.3 ms, 15 ± 2.9 ms, P = 0.04). Conduction time within the interatrium was significantly longer in the HF dogs than that in the control and HF + RSD dogs (39 ± 4 ms vs 31 ± 3 ms, 33 ± 4 ms; P = 0.03). Window of vulnerability (WOV) of AF was widened in the HF dogs than in the HF + RSD dogs (37 ± 5 ms vs 14 ± 3 ms; P < 0.01), while AF could not be induced (WOV = 0) in the control dogs during S1 S2 stimulation. The voltage in the threshold for AF inducibility was lower during ganglionated plexi stimulation in the HF dogs than in the control and HF + RSD dogs (1.8 ± 0.6 V vs 2.5 ± 0.6 V, 2.4 ± 0.4 V; P = 0.04). RSD could reverse the atrial electrical remodeling and decrease AF inducibility in dogs with pacing-induced HF. ©2014 Wiley Periodicals, Inc.

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

Renal sympathetic denervation suppresses atrial fibrillation induced by acute atrial ischemia/infarction through inhibition of cardiac sympathetic activity.

PubMed

Zhou, Qina; Zhou, Xianhui; TuEr-Hong, ZuKe-la; Wang, Hongli; Yin, Tingting; Li, Yaodong; Zhang, Ling; Lu, Yanmei; Xing, Qiang; Zhang, Jianghua; Yang, Yining; Tang, Baopeng

2016-01-15

This study aims to explore the effects of renal sympathetic denervation (RSD) on atrial fibrillation (AF) inducibility and sympathetic activity induced by acute atrial ischemia/infarction. Acute ischemia/infarction was induced in 12 beagle dogs by ligating coronary arteries that supply the atria. Six dogs in the sham-RSD group did not undergo RSD, and six dogs without coronary artery ligation served as controls. AF induction rate, sympathetic discharge, catecholamine concentration and densities of tyrosine hydroxylase-positive nerves were measured. Acute atrial ischemia/infarction resulted in a significant increase of AF induction rate, which was decreased by RSD compared to controls (P<0.05). The root-mean-square peak value, peak area and number of sympathetic discharges were significantly augmented by atrial ischemia relative to the baseline and control (P<0.05). The number of sympathetic discharges was significantly reduced in the RSD group, compared to the control and sham-RSD groups (P<0.05). Norepinephrine and epinephrine concentrations in the atria, ventricle and kidney were elevated by atrial ischemia/infarction, but were reduced by RSD (P<0.05). Sympathetic hyperactivity was associated with pacing-induced AF after acute atrial ischemia/infarction. RSD has the potential to reduce the incidence of new-onset AF after acute atrial ischemia/infarction. The inhibition of cardiac sympathetic activity by RSD may be one of the major underlying mechanisms for the marked reduction of AF inducibility. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Determination of volatile corrosion inhibitors by capillary electrophoresis.

PubMed

Pereira, Elisabete A; Tavares, Marina F M

2004-10-08

In this work, a capillary electrophoresis (CE) method using indirect UV detection (214nm) for the simultaneous determination of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diethylethanolamine (DEEA), monocyclohexylamine (MCHA) and dicyclohexylamine (DCHA) in water/ethanol extracts of wrapping materials containing volatile corrosion inhibitors (VCIs) was described. A running buffer consisting of 0.010 molL(-1) imidazole, 0.010 molL(-1) 2-hydroxyisobutyric acid (HIBA) and 0.010 molL(-1) 18-crown-6 ether enabled separation of the analytes in less than 7 min. A few method validation parameters were determined revealing good migration time repeatability (<0.7% RSD) and area repeatability (< 1.8% RSD). Limits of detection were in the range of 0.52-1.54 mg L(-1). Recovery values were in the range of 94.8-100.9%. The methodology was successfully applied to the analysis of three commercial products (VCI treated paper, foam and plastic). The concentration of amines in these materials varied from 0.050 to 22.3% (w/w).

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.

Optimization of microwave-assisted extraction with saponification (MAES) for the determination of polybrominated flame retardants in aquaculture samples.

PubMed

Fajar, N M; Carro, A M; Lorenzo, R A; Fernandez, F; Cela, R

2008-08-01

The efficiency of microwave-assisted extraction with saponification (MAES) for the determination of seven polybrominated flame retardants (polybrominated biphenyls, PBBs; and polybrominated diphenyl ethers, PBDEs) in aquaculture samples is described and compared with microwave-assisted extraction (MAE). Chemometric techniques based on experimental designs and desirability functions were used for simultaneous optimization of the operational parameters used in both MAES and MAE processes. Application of MAES to this group of contaminants in aquaculture samples, which had not been previously applied to this type of analytes, was shown to be superior to MAE in terms of extraction efficiency, extraction time and lipid content extracted from complex matrices (0.7% as against 18.0% for MAE extracts). PBBs and PBDEs were determined by gas chromatography with micro-electron capture detection (GC-muECD). The quantification limits for the analytes were 40-750 pg g(-1) (except for BB-15, which was 1.43 ng g(-1)). Precision for MAES-GC-muECD (%RSD < 11%) was significantly better than for MAE-GC-muECD (%RSD < 20%). The accuracy of both optimized methods was satisfactorily demonstrated by analysis of appropriate certified reference material (CRM), WMF-01.

Development of a solenoid pumped in situ zinc analyzer for environmental monitoring

USGS Publications Warehouse

Chapin, T.P.; Wanty, R.B.

2005-01-01

A battery powered submersible chemical analyzer, the Zn-DigiScan (Zn Digital Submersible Chemical Analyzer), has been developed for near real-time, in situ monitoring of zinc in aquatic systems. Microprocessor controlled solenoid pumps propel sample and carrier through an anion exchange column to separate zinc from interferences, add colorimetric reagents, and propel the reaction complex through a simple photometric detector. The Zn-DigiScan is capable of self-calibration with periodic injections of standards and blanks. The detection limit with this approach was 30 ??g L-1. Precision was 5-10% relative standard deviation (R.S.D.) below 100 ??g L-1, improving to 1% R.S.D. at 1000 ??g L-1. The linear range extended from 30 to 3000 ??g L-1. In situ field results were in agreement with samples analyzed by inductively coupled plasma mass spectrometry (ICPMS). This pump technology is quite versatile and colorimetric methods with complex online manipulations such as column reduction, preconcentration, and dilution can be performed with the DigiScan. However, long-term field deployments in shallow high altitude streams were hampered by air bubble formation in the photometric detector. ?? 2005 Elsevier B.V. All rights reserved.

Quantitation of Thioprolines in Grape Wine by Isotope Dilution-Liquid Chromatography-Tandem Mass Spectrometry.

PubMed

Liu, Jingjing; Meng, Xiangpeng; Chan, Wan

2016-02-17

Cysteine reacts with reactive carbonyls to form thioprolines, which have been demonstrated to possess various pharmaceutical properties. Therefore, thioproline formation is considered as a major detoxification pathway for carcinogenic reactive carbonyls. In this study, we report the initial identification of thiazolidine-4-carboxylic acid (1) and 2-methylthiazolidine-4-carboxylic acid (2), two very common thioprolines, formed by reacting formaldehyde and acetaldehyde with cysteine in grape wine samples. We have developed an isotope dilution-liquid chromatography-tandem mass spectrometry method featuring high sensitivity (limit of detection of ≤1.5 ng/mL) and selectivity to quantitate compounds 1 and 2. The method after validated to be highly accurate (recovery of ≥92%) and precise [intraday relative standard deviation (RSD) of ≤4.1% and interday RSD of ≤9.7%] was applied to determine the varying compound 1 and 2 contents in grape wine samples. Results revealed the grape type and storage duration-dependent formation of thioprolines in grape wines. Overall, the results are expected to facilitate compound-dependent investigations of the health benefits of grape wine, and our findings could be adopted to predict the age of grape wine.

Simultaneous determination of organophosphorus pesticides in fruits and vegetables using atmospheric pressure gas chromatography quadrupole-time-of-flight mass spectrometry.

PubMed

Cheng, Zhipeng; Dong, Fengshou; Xu, Jun; Liu, Xingang; Wu, Xiaohu; Chen, Zenglong; Pan, Xinglu; Gan, Jay; Zheng, Yongquan

2017-09-15

This paper describes the application of atmospheric pressure gas chromatography quadrupole-time-of-flight mass spectrometry for the simultaneous determination of organophosphorus pesticides in apple, pear, tomato, cucumber and cabbage. Soft ionization with atmospheric pressure ionization source was compared with traditional electron impact ionization (EI). The sensitivity of GC coupled to atmospheric pressure ionization (APGC) for all the analytes was enhanced by 1.0-8.2 times. The ionization modes with atmospheric pressure ionization source was studied by comparing the charge-transfer and proton-transfer conditions. The optimized QuEChERs method was used to pretreat the samples. The calibration curves were found linear from 10 to 1000μg/L, obtaining correlation coefficients higher than 0.9845. Satisfactory mean recovery values, in the range of 70.0-115.9%, and satisfactory precision, with all RSD r <19.7% and all RSD R values <19.5% at the three fortified concentration levels for all the fifteen OPPs. The results demonstrate the potential of APGC-QTOF-MS for routine quantitative analysis of organophosphorus pesticide in fruits and vegetables. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analytical strategy for the determination of non-steroidal anti-inflammatory drugs in plasma and improved analytical strategy for the determination of authorized and non-authorized non-steroidal anti-inflammatory drugs in milk by LC-MS/MS.

PubMed

Dowling, Geraldine; Malone, Edward; Harbison, Tom; Martin, Sheila

2010-07-01

A sensitive and selective method for the determination of six non-steroidal anti-inflammatory drugs (NSAIDs) in bovine plasma was developed. An improved method for the determination of authorized and non-authorized residues of 10 non-steroidal anti-inflammatory drugs in milk was developed. Analytes were separated and acquired by high performance liquid chromatography coupled with an electrospray ionisation tandem mass spectrometer (ESI-MS/MS). Target compounds were acidified in plasma, and plasma and milk samples were extracted with acetonitrile and both extracts were purified on an improved solid phase extraction procedure utilising Evolute ABN cartridges. The accuracy of the methods for milk and plasma was between 73 and 109%. The precision of the method for authorized and non-authorized NSAIDs in milk and plasma expressed as % RSD, for the within lab reproducibility was less than 16%. The % RSD for authorized NSAIDs at their associated MRL(s) in milk was less than 10% for meloxicam, flunixin and tolfenamic acid and was less than 25% for hydroxy flunixin. The methods were validated according to Commission Decision 2002/657/EC.

Polypyrrole-magnetite dispersive micro-solid-phase extraction combined with ultraviolet-visible spectrophotometry for the determination of rhodamine 6G and crystal violet in textile wastewater.

PubMed

Kamaruddin, Amirah Farhan; Sanagi, Mohd Marsin; Wan Ibrahim, Wan Aini; Md Shukri, Dyia S; Abdul Keyon, Aemi S

2017-11-01

Polypyrrole-magnetite dispersive micro-solid-phase extraction method combined with ultraviolet-visible spectrophotometry was developed for the determination of selected cationic dyes in textile wastewater. Polypyrrole-magnetite was used as adsorbent due to its thermal stability, magnetic properties, and ability to adsorb Rhodamine 6G and crystal violet. Dispersive micro-solid-phase extraction parameters were optimized, including sample pH, adsorbent amount, extraction time, and desorption solvent. The optimum polypyrrole-magnetite dispersive micro-solid phase-extraction conditions were sample pH 8, 60 mg polypyrrole-magnetite adsorbent, 5 min of extraction time, and acetonitrile as the desorption solvent. Under the optimized conditions, the polypyrrole-magnetite dispersive micro-solid-phase extraction with ultraviolet-visible method showed good linearity in the range of 0.05-7 mg/L (R 2  > 0.9980). The method also showed a good limit of detection for the dyes (0.05 mg/L) and good analyte recoveries (97.4-111.3%) with relative standard deviations < 10%. The method was successfully applied to the analysis of dyes in textile wastewater samples where the concentration found was 1.03 mg (RSD ±7.9%) and 1.13 mg/L (RSD ± 4.6%) for Rhodamine 6G and crystal violet, respectively. It can be concluded that this method can be adopted for the rapid extraction and determination of dyes at trace concentration levels. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Telltale Signs and Symptoms of CRPS/RSD

MedlinePlus

... Living With CRPS/RSD Symptoms of CRPS/RSD Definition of CRPS Diagnosed: Now What? Coping Strategies Caregivers CRPS Comfortable Clothing For Youth Stories of Hope Research/Medical Clinical Guidelines Treatments Educational Presentations RSDSA Videos Accredited Course ...

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.

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 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.

Enhanced chemiluminescence of carminic acid-permanganate by CdS quantum dots and its application for sensitive quenchometric flow injection assays of cloxacillin.

PubMed

Khataee, Alireza; Hasanzadeh, Aliyeh; Lotfi, Roya; Joo, Sang Woo

2016-05-15

A novel chemiluminescence (CL) system is introduced based on the oxidation of carminic acid by KMnO4 in acidic conditions. CdS quantum dots (QDs) were synthesized using a facile hydrothermal method which efficiently enhanced the intensity of the CL system. A possible mechanism for the proposed system is presented using the kinetic curves, CL spectra, photoluminescence (PL), and ultraviolet-visible (UV-Vis) analysis. The emission intensity of the KMnO4-carminic acid-CdS QDs system was quenched in the presence of a trace level of cloxacillin. Based on this quenching effect, a novel and sensitive flow injection CL method was developed for determining cloxacillin concentrations. At optimal experimental conditions, the decreased CL intensity had a good linear relation with the cloxacillin concentration in the range of 0.008 to 22.0 mg L(-1). The detection limit (3σ) was 5.8 µg L(-1). The precision of the method was calculated by analyzing samples containing 4.0 mg L(-1) of cloxacillin (n=11), and the relative standard deviations (RSD%) were 2.08%. The feasibility of the method is also demonstrated for determining cloxacillin concentrations in environmental water samples and a pharmaceutical formulation. Copyright © 2016 Elsevier B.V. All rights reserved.

Thin-layer chromatography coupled with high performance liquid chromatography for determining tetrabromobisphenol A/S and their derivatives in soils.

PubMed

Liu, Aifeng; Shen, Zhaoshuang; Tian, Yong; Shi, Rongguang; Liu, Yi; Zhao, Zongshan; Xian, Mo

2017-12-01

As brominated flame retardants (BFRs), tetrabromobisphenol A/S (TBBPA/S) and their derivatives have raised wide concerns owing to their widely usage, distributions and adverse effects on human health, thus monitoring these BFRs was urgently needed. In this study, a rapid and cost-effective method based on thin-layer chromatography (TLC) sample pre-treatment coupled with high performance liquid chromatography-diode array detector (HPLC-DAD) (UV=214nm) was developed for determining TBBPA/S and their derivatives in soils, including TBBPA, TBBPA bis(allyl ether) (TBBPA-BAE), TBBPA bis(2,3-dibromopropyl ether) (TBBPA-BDBPE), TBBPS bis(allyl ether) (TBBPS-BAE) and TBBPS bis(2,3-dibromopropyl ether) (TBBPS-BDBPE). The method detection limits (MDLs) and the method quantification limits (MQLs) for these BFRs ranged from 0.023 to 0.087μgg -1 dw and 0.076-0.29μgg -1 dw, respectively. The recoveries were 41-108% and both RSD of repeatability and intermediate precision were less than 11%. The developed method presented good performance for analyzing natural soil samples collected from BFRs industrial park, suggesting its great application potential for monitoring environmental TBBPA/S and their derivatives. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrochemical Sensor for Organophosphate Pesticides and Nerve Agents Using Zirconia Nanoparticles as Selective Sorbents

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

Liu, Guodong; Lin, Yuehe

2005-09-15

Electrochemical sensor for detection of organophosphate (OP) pesticides and nerve agents using zirconia (ZrO₂) nanoparticles as selective sorbents is presented. Zirconia nanoparticles were electrodynamically deposited onto the polycrystalline gold electrode by cyclic voltammetry. Because of a strong affinity of zirconia to the phosphoric group, nitroaromatic OPs strongly bind to the ZrO₂ nanoparticle surface. The electrochemical characterization and anodic stripping voltammetric performance of bound OPs were evaluated using cyclic voltammetric and square-wave voltammetric (SWV) analysis. SWV was used to monitor the amount of bound OPs and provide simple, fast, and facile quantitative methods for nitroaromatic OP compounds. The sensor surface canmore » be regenerated by successively running SWV scanning. Operational parameters, including the amount of nanoparticles, adsorption time, and the pH of the reaction medium have been optimized. The stripping voltammetric response is highly linear over the 5–200 ng/mL (ppb) methyl parathion range examined (2-min adsorption), with a detection limit of 1 ng/mL (10 min accumulation), and good precision (RSD=5.3 %, n = 10). The promising stripping voltammetric performances open new opportunities for fast, simple, and sensitive analyzing of OPs in environmental and biological samples. These findings can lead to a widespread use of electrochemical sensors to detect OP contaminates.« less

Sequential injection system for simultaneous determination of sucrose and phosphate in cola drinks using paired emitter-detector diode sensor.

PubMed

Saetear, Phoonthawee; Khamtau, Kittiwut; Ratanawimarnwong, Nuanlaor; Sereenonchai, Kamonthip; Nacapricha, Duangjai

2013-10-15

This work presents the simultaneous determination of sucrose and phosphate by using sequential injection (SI) system with a low cost paired emitter-detector diode (PEDD) light sensor. The PEDD uses two 890 nm LEDs. Measurement of sucrose in Brix unit was carried out based on the detection of light refraction occurring at the liquid interface (the schlieren effect) between the sucrose solution and water. Phosphate was measured from the formation of calcium phosphate with turbidimetric detection. With careful design of the loading sequence and volume (sample--precipitating reagent--sample), simultaneous detection of sucrose and phosphate was accomplished with the single PEDD detector. At the optimized condition, linear calibrations from 1 to 7 Brix sucrose and from 50 to 200mg PO4(3-)L(-1) were obtained. Good precision at lower than 2% RSD (n=10) for both analytes with satisfactory throughput of 21 injections h(-1) was achieved. The method was successfully applied for the determination of sucrose and phosphate in cola drinks. The proposed method is readily applicable for automation and is found to be an alternative method to conventional procedures for on-line quality control process in cola drink industry. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Novel coatings for stir bar sorptive extraction to determine pharmaceuticals and personal care products in environmental waters by liquid chromatography and tandem mass spectrometry.

PubMed

Gilart, Núria; Miralles, Núria; Marcé, Rosa Maria; Borrull, Francesc; Fontanals, Núria

2013-04-24

Two new commercially available polar coatings for stir bar sorptive extraction (SBSE), consisting of polyacrylate (PA) with a proportion of polyethyleneglycol (PEG) (Acrylate Twister(®)) and PEG modified silicone (EG Silicone Twister(®)), were evaluated and compared with the classic coating based on polydimethylsiloxane (PDMS Twister(®)) for the extraction of a group of pharmaceuticals and personal care products (PPCPs) from wastewater samples. The SBSE parameters, such as sample pH, agitation speed, extraction temperature, extraction time, desorption solvent and time, were optimised in order to achieve suitable sorption of the target analytes. The EG Silicone coating enabled more efficient extraction of some polar compounds as well as improving the sorption of apolar compounds, in comparison with the other two coatings. Finally, the method of SBSE followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) using the EG Silicone coating was validated achieving good linearity (r(2)>0.994, except for CBZ (r(2)>0.989)), precision (%RSD<17%) and low limits of quantification (LOQs) (20-40 ng L(-1)). The SBSE/LC-MS/MS methodology was applied for the determination of PPCPs in wastewater samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Separation of alpha-, beta-, gamma-, delta-tocopherols and alpha-tocopherol acetate on a pentaerythritol diacrylate monostearate-ethylene dimethacrylate monolith by capillary electrochromatography.

PubMed

Chaisuwan, Patcharin; Nacapricha, Duangjai; Wilairat, Prapin; Jiang, Zhengjin; Smith, Norman W

2008-06-01

This work reports the first use of a monolith with method development for the separation of tocopherol (TOH) compounds by CEC with UV detection. A pentaerythritol diacrylate monostearate-ethylene dimethacrylate (PEDAS-EDMA) monolithic column has been investigated for an optimised condition to separate alpha-, beta-, gamma- and delta-TOHs, and alpha-tocopherol acetate (TAc). The PEDAS-EDMA monolith showed a remarkably good selectivity for separation of the TOH isomers including the beta- and gamma-isomers which are not easily separated by standard C8 or C18 particle-packed columns. Retention studies indicated that an RP mechanism was involved in the separation on the PEDAS-EDMA column, but polar interactions with the underlying ester and hydroxyl groups enhanced the separation of the problematic beta- and gamma-isomers. Separation of all the compounds was achieved within 25 min using 3:10:87 v/v/v 100 mM Tris buffer (pH 9.3)/methanol/ACN as the mobile phase. The method was successfully applied to a pharmaceutical sample with recoveries from 93 to 99%. Intraday and interday precisions (%RSD) for peak area and retention time were less than 2.3. LODs for all four TOHs and TAc were below 1 ppm.

Capillary electrophoresis method with UV-detection for analysis of free amino acids concentrations in food.

PubMed

Omar, Mei Musa Ali; Elbashir, Abdalla Ahmed; Schmitz, Oliver J

2017-01-01

Simple and inexpensive capillary electrophoresis with UV-detection method (CE-UV) was optimized and validated for determination of six amino acids namely (alanine, asparagine, glutamine, proline, serine and valine) for Sudanese food. Amino acids in the samples were derivatized with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) prior to CE-UV analysis. Labeling reaction conditions (100mM borate buffer at pH 8.5, labeling reaction time 60min, temperature 70°C and NBD-Cl concentration 40mM) were systematically investigated. The optimal conditions for the separation were 100mM borate buffer at pH 9.7 and detected at 475nm. The method was validated in terms of linearity, limit of detection (LOD), limit of quantification (LOQ), precision (repeatability) (RSD%) and accuracy (recovery). Good linearity was achieved for all amino acids (r(2)>0.9981) in the concentration range of 2.5-40mg/L. The LODs in the range of 0.32-0.56mg/L were obtained. Recoveries of amino acids ranging from 85% to 108%, (n=3) were obtained. The validated method was successfully applied for the determination of amino acids for Sudanese food samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Combination of solid-phase extraction with dispersive liquid-liquid microextraction followed by GC-MS for determination of pesticide residues from water, milk, honey and fruit juice.

PubMed

Shamsipur, Mojtaba; Yazdanfar, Najmeh; Ghambarian, Mahnaz

2016-08-01

In this work, an effective preconcentration method for the extraction and determination of traces of multi-residue pesticides was developed using solid-phase extraction (SPE) coupled with dispersive liquid-liquid microextraction and gas chromatography-mass spectrometry (GC-MS). Variables affecting the performance of both extraction steps such as type and volume of elution and extraction solvents, breakthrough volume, salt addition, extraction time were thoroughly investigated. The proposed method resulted in good linearities (R(2)>0.9915) over the ranges of 1-10,000ngkg(-1), limits of detection (LODs) in the range of 0.5-1.0ngkg(-1) at S/N=3, and precision of RSD% of ⩽11.8. Under optimal conditions, the preconcentration factors were obtained in the range of 2362-10,593 for 100mL sample solutions. Comparison of the proposed method with other ones demonstrated that SPE-DLLME method provides higher extraction efficiency and larger preconcentration factor for determination of pesticides residues. Further, it is simple, inexpensive, highly sensitive, and can be successfully applied to separation, preconcentration and determination of the pesticides (and other noxious materials) in different real food samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of several solid-phase extraction sorbents for continuous determination of amines in water by gas chromatography-mass spectrometry.

PubMed

Jurado-Sánchez, Beatriz; Ballesteros, Evaristo; Gallego, Mercedes

2009-08-15

A semiautomatic method has been proposed for the determination of different types of amines in water samples including anilines, chloroanilines, N-nitrosamines and aliphatic amines. The analytes were retained on a solid-phase extraction sorbent column and after elution, 1 microL of the extract was analysed by gas chromatography coupled with electron impact ionization mass spectrometry. A systematic overview is given of the advantages and disadvantages of several sorbents (LiChrolut EN, Oasis HLB, RP-C(18), graphitized carbon black, fullerenes and nanotubes) in the retention of amine compounds and based on sensitivity, selectivity and reliability. The retention efficiency for the studied amines was higher (ca. 100%) with LiChrolut EN and Oasis HLB than it was with RP-C(18) and fullerenes (53 and 62%, respectively, on average). Detection limits of 0.5-16 ng L(-1) for the 27 amines studied were obtained when using a sorbent column containing 75 mg of LiChrolut EN for 100mL of sample, the RSD being lower than 6.5%. The method was applied with good accuracy and precision in the determination of amines in various types of water including river, pond, tap, well, drinking, swimming pool and waste.

An optimized method for neurotransmitters and their metabolites analysis in mouse hypothalamus by high performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry.

PubMed

Yang, Zong-Lin; Li, Hui; Wang, Bing; Liu, Shu-Ying

2016-02-15

Neurotransmitters (NTs) and their metabolites are known to play an essential role in maintaining various physiological functions in nervous system. However, there are many difficulties in the detection of NTs together with their metabolites in biological samples. A new method for NTs and their metabolites detection by high performance liquid chromatography coupled with Q Exactive hybrid quadruple-orbitrap high-resolution accurate mass spectrometry (HPLC-HRMS) was established in this paper. This method was a great development of the applying of Q Exactive MS in the quantitative analysis. This method enabled a rapid quantification of ten compounds within 18min. Good linearity was obtained with a correlation coefficient above 0.99. The concentration range of the limit of detection (LOD) and the limit of quantitation (LOQ) level were 0.0008-0.05nmol/mL and 0.002-25.0nmol/mL respectively. Precisions (relative standard deviation, RSD) of this method were at 0.36-12.70%. Recovery ranges were between 81.83% and 118.04%. Concentrations of these compounds in mouse hypothalamus were detected by Q Exactive LC-MS technology with this method. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of isothiazolinone biocides in paper for food packaging by ultra-high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Lin, Q-B; Wang, T-J; Song, H; Li, B

2010-12-01

A novel and simple method to detect isothiazolinone-type biocides (2-methyl-3-isothiazolinone (MI), 5-chloro-2-methyl-3-isothiazolinone (CMI), 1,2-benzisothiazolinone (BIT) and 2-octyl-3-isothiazolinone (OIT)) in paper used for food packaging by ultrasonic extraction coupled with UPLC-MS/MS was developed. Parameters affecting process efficiency such as extraction solvents, UPLC mobile phase, gradient elution procedure and MS/MS conditions were studied to optimise the operating conditions. Using the optimised gradient elution procedure, the retention time was less than 6 min. The limits of detection (LODs) were found to be between 0.001 and 0.010 mg kg⁻¹, which was validated using actual concentrations. After diluting the standard solution with a blank matrix, the linear calibration curve ranges were 0.002-1.000 mg kg⁻¹ for BIT and OIT, 0.005-1.000 mg kg⁻¹ for MI, and 0.020-1.000 mg kg⁻¹ for CMI, with correlation coefficients higher than 0.9985 (n = 6). A good level of precision with a mean recovery greater than 81.3% and a relative standard deviation (RSD) less than 6.2% were also obtained. A methodology has been proposed for the analysis of isothiazolinones in paper.

Analytical method for lipoperoxidation relevant reactive aldehydes in human sera by high-performance liquid chromatography-fluorescence detection.

PubMed

El-Maghrabey, Mahmoud H; Kishikawa, Naoya; Ohyama, Kaname; Kuroda, Naotaka

2014-11-01

A validated, simple and sensitive HPLC method was developed for the simultaneous determination of lipoperoxidation relevant reactive aldehydes: glyoxal (GO), acrolein (ACR), malondialdehyde (MDA), and 4-hydroxy-2-nonenal (HNE) in human serum. The studied aldehydes were reacted with 2,2'-furil to form fluorescent difurylimidazole derivatives that were separated on a C18 column using gradient elution and fluorescence detection at excitation and emission wavelengths of 250 and 355nm, respectively. The method showed good linearity over the concentration ranges of 0.100-5.00, 0.200-10.0, 0.200-40.0, and 0.400-10.0nmol/mL for GO, ACR, HNE, and MDA, respectively, with detection limits ranging from 0.030 to 0.11nmol/mL. The percentage RSD of intraday and interday precision did not exceed 5.0 and 6.2%, respectively, and the accuracy (%found) ranged from 95.5 to 103%. The proposed method was applied for monitoring the four aldehydes in sera of healthy, diabetic, and rheumatic human subjects with simple pretreatment steps and without interference from endogenous components. By virtue of its high sensitivity and accuracy, our method enabled detection of differences between analytes concentrations in sera of human subjects under different clinical conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

A robust method for determining water-extractable alkylphenol polyethoxylates in textile products by reaction-based headspace gas chromatography.

PubMed

Zhang, Shu-Xin; Chai, Xin-Sheng; Huang, Bo-Xi; Mai, Xiao-Xia

2015-08-07

Alkylphenol polyethoxylates (APEO), surfactants used in the production of textiles, have the potential to move from the fabric to the skin of the person wearing the clothes, posing an inherent risk of adverse health consequences. Therefore, the textile industry needs a fast, robust method for determining aqueous extractable APEO in fabrics. The currently-favored HPLC methods are limited by the presence of a mixture of analytes (due to the molecular weight distribution) and a lack of analytical standards for quantifying results. As a result, it has not been possible to reach consensus on a standard method for the determination of APEO in textiles. This paper addresses these limitations through the use of reaction-based head space-gas chromatography (HS-GC). Specifically, water is used to simulate body sweat and extract APEO. HI is then used to react the ethoxylate chains to depolymerize the chains into iodoethane that is quantified through HS-GC, providing an estimate of the average amount of APEO in the clothing. Data are presented to justify the optimal operating conditions; i.e., water extraction at 60°C for 1h and reaction with a specified amount of HI in the headspace vial at 135°C for 4h. The results show that the HS-GC method has good precision (RSD<10%) and good accuracy (recoveries from 95 to 106%) for the quantification of APEO content in textile and related materials. As such, the method should be a strong candidate to become a standard method for such determinations. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous extraction and determination of phthalate esters in aqueous solution by yolk-shell magnetic mesoporous carbon-molecularly imprinted composites based on solid-phase extraction coupled with gas chromatography-mass spectrometry.

PubMed

Yang, Rui; Liu, Yuxin; Yan, Xiangyang; Liu, Shaomin

2016-12-01

A rapid, sensitive and accurate method for the simultaneous extraction and determination of five types of trace phthalate esters (PAEs) in environmental water and beverage samples using magnetic molecularly imprinted solid-phase extraction (MMIP-SPE) coupled with gas chromatography-mass spectrometry (GC-MS) was developed. A novel type of molecularly imprinted polymers on the surface of yolk-shell magnetic mesoporous carbon (Fe 3 O 4 @void@C-MIPs) was used as an efficient adsorbent for selective adsorption of phthalate esters based on magnetic solid-phase extraction (MSPE). The real samples were first preconcentrated by Fe 3 O 4 @void@C-MIPs, subsequently extracted by eluent and finally determined by GC-MS after magnetic separation. Several variables affecting the extraction efficiency of the analytes, including the type and volume of the elution solvent, amount of adsorbent, extraction time, desorption time and pH of the sample solution, were investigated and optimized. Validation experiments indicated that the developed method presented good linearity (R 2 >0.9961), satisfactory precision (RSD<6.7%), and high recovery (86.1-103.1%). The limits of detection ranged from 1.6ng/L to 5.2ng/L and the enrichment factor was in the range of 822-1423. The results indicated that the novel method had the advantages of convenience, good sensitivity, and high efficiency, and it could also be successfully applied to the analysis of PAEs in real samples. Copyright © 2016. Published by Elsevier B.V.

Simultaneous determination of ingredients in a cold medicine by cyclodextrin-modified microemulsion electrokinetic chromatography.

PubMed

Okamoto, Hitoshi; Nakajima, Toshiaki; Ito, Yuji; Aketo, Takao; Shimada, Kenji; Yamato, Susumu

2005-03-09

Cyclodextrin-modified microemulsion electrokinetic chromatography (CD-MEEKC) was used to simultaneously determine 14 active ingredients (thiamine nitrate, anhydrous caffeine, acetaminophen, riboflavin, guaifenesin, pseudoephedrine hydrochloride, ascorbic acid, ethenzamide, DL-methylephedrine hydrochloride, dihydrocodeine phosphate, ibuprofen, noscapine, carbinoxamine maleate, and bromhexine hydrochloride) in a cold medicine. Separation of the ingredients was optimized by changing the SDS concentration and oil type and the addition of 2-propanol and cyclodextrin (CD) to the separation solution. The separation selectivity was improved dramatically by changing CD type. All of the active ingredients and formulation excipients were successfully separated with the use of a separation solution consisting of 0.81% (w/w) pentane, 6.61% (w/w) 1-butanol, 2% (w/w) 2-propanol, 4.47% (w/w) SDS, and 86.11% (w/w) 10 mM sodium tetraborate solution with 3 mM 2,6-di-O-methyl-beta-CD. The established method was then validated and demonstrated to be applicable to the determination of the active ingredients in a model cold medicine. No interference from the formulation excipients was observed. Good linearities were obtained with correlation coefficients above 0.999. Recovery and precision ranged from 99.1 to 100.7% and from 0.5 to 2.8% R.S.D., respectively. The detection limit for ingredients ranged from 0.6 to 4.2 microg ml(-1). Good agreement was obtained between the established method and the traditional HPLC method. These results suggest that CD-MEEKC can be used for the determination of multiple ingredients in cold medicine.

Quantitative analysis of arbutin and hydroquinone in strawberry tree (Arbutus unedo L., Ericaceae) leaves by gas chromatography-mass spectrometry.

PubMed

Jurica, Karlo; Karačonji, Irena Brčić; Šegan, Sandra; Opsenica, Dušanka Milojković; Kremer, Dario

2015-09-01

The phenolic glycoside arbutin and its metabolite with uroantiseptic activity hydroquinone occur naturally in the leaves of various medicinal plants and spices. In this study, an extraction procedure coupled with gas chromatography-mass spectrometry (GC-MS) was developed to determine arbutin and hydroquinone content in strawberry tree (Arbutus unedo L., Ericaceae) leaves. The method showed good linearity (R2>0.9987) in the tested concentration range (0.5-200 μg mL(-1)), as well as good precision (RSD<5%), analytical recovery (96.2-98.0%), and sensitivity (limit of detection=0.009 and 0.004 μg mL(-1) for arbutin and hydroquinone, respectively). The results obtained by the validated GC-MS method corresponded well to those obtained by high performance liquid chromatography (HPLC) method. The proposed method was then applied for determining arbutin and hydroquinone content in methanolic leaf extracts. The amount of arbutin in the leaves collected on the island of Koločep (6.82 mg g(-1) dry weight) was found to be higher (tpaired=43.57, tc=2.92) in comparison to the amount of arbutin in the leaves collected on the island of Mali Lošinj (2.75 mg g(-1) dry weight). Hydroquinone was not detected in any of the samples. The analytical features of the proposed GC-MS method demonstrated that arbutin and hydroquinone could be determined alternatively by gas chromatography. Due to its wide concentration range, the method could also be suitable for arbutin and hydroquinone analysis in leaves of other plant families (Rosaceae, Lamiaceae, etc.).

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.

Renal sympathetic denervation attenuates hypertension and vascular remodeling in renovascular hypertensive rats.

PubMed

Li, Peng; Huang, Pei-Pei; Yang, Yun; Liu, Chi; Lu, Yan; Wang, Fang; Sun, Wei; Kong, Xiang-Qing

2017-01-01

Li P, Huang P, Yang Y, Liu C, Lu Y, Wang F, Sun W, Kong X. Renal sympathetic denervation attenuates hypertension and vascular remodeling in renovascular hypertensive rats. J Appl Physiol 122: 121-129, 2017. First published October 14, 2016; doi:10.1152/japplphysiol.01019.2015-Sympathetic activity is enhanced in patients with essential or secondary hypertension, as well as in various hypertensive animal models. Therapeutic targeting of sympathetic activation is considered an effective antihypertensive strategy. We hypothesized that renal sympathetic denervation (RSD) attenuates hypertension and improves vascular remodeling and renal disease in the 2-kidney, 1-clip (2K1C) rat model. Rats underwent 2K1C modeling or sham surgery; then rats underwent RSD or sham surgery 4 wk later, thus resulting in four groups (normotensive-sham, normotensive-RSD, 2K1C-sham, and 2K1C-RSD). Norepinephrine was measured by ELISA. Echocardiography was used to assess heart function. Fibrosis and apoptosis were assessed by Masson and TUNEL staining. Changes in mean arterial blood pressure in response to hexamethonium and plasma norepinephrine levels were used to evaluate basal sympathetic nerve activity. The 2K1C modeling success rate was 86.8%. RSD reversed the elevated systolic blood pressure induced by 2K1C, but had no effect on body weight. Compared with rats in the 2K1C-sham group, rats in the 2K1C-RSD group showed lower left ventricular mass/body weight ratio, interventricular septal thickness in diastole, left ventricular end-systolic diameter, and left ventricular posterior wall thickness in systole, whereas fractional shortening and ejection fraction were higher. Right kidney apoptosis and left kidney hypertrophy were not changed by RSD. Arterial fibrosis was lower in animals in the 2K1C-RSD group compared with those in the 2K1C-sham group. RSD reduced plasma norepinephrine and basal sympathetic activity in rats in the 2K1C-RSD group compared with rats in the 2K1C-sham group. These results suggest a possible clinical efficacy of RSD for renovascular hypertension. The effects of renal sympathetic denervation (RSD) on hypertension, cardiac function, vascular fibrosis, and renal apoptosis were studied in the 2K1C rat model. Results showed that RSD attenuated hypertension, improved vascular remodeling, and reduced vascular fibrosis through decreased sympathetic activity in the 2K1C rat model, but it did not change the kidney size, renal apoptosis, or renal caspase-3 expression. These results could suggest possible clinical efficacy of RSD for renovascular hypertension. Copyright © 2017 the American Physiological Society.

Beneficial effects of renal sympathetic denervation on cardiovascular inflammation and remodeling in essential hypertension.

PubMed

Dörr, Oliver; Liebetrau, Christoph; Möllmann, Helge; Mahfoud, Felix; Ewen, Sebastian; Gaede, Luise; Troidl, Christian; Hoffmann, Jedrzej; Busch, Nikolai; Laux, Gerald; Wiebe, Jens; Bauer, Timm; Hamm, Christian; Nef, Holger

2015-02-01

Renal sympathetic denervation (RSD) represents a potential treatment option for certain patients with resistant arterial hypertension (HT). HT is associated with chronic vascular inflammation and remodeling, contributing to progressive vascular damage, and atherosclerosis. The present study aimed to evaluate the influence of RSD on cardiovascular inflammation and remodeling by determining serum levels of interleukin-6 (IL-6), high-sensitive C-reactive protein (hsCRP), matrix metalloproteinases (MMP), and tissue inhibitor of metalloproteinases (TIMP). A total of 60 consecutive patients (age 67.9 ± 9.6 years) undergoing RSD were included. A therapeutic response was defined as an office systolic blood pressure (SBP) reduction of >10 mmHg 6 months after RSD. Venous serum samples for measurement of hsCRP, IL-6, MMP-2, MMP-9, and TIMP-1 were collected prior to and 6 months after RSD. A significant reduction in office SBP of 26.4 mmHg [SBPbaseline 169.3 mmHg (SD 11.3), p < 0.001] was documented 6 months after RSD. The serum levels of hsCRP (p < 0.001) and the pro-inflammatory cytokine IL-6 (p < 0.001) were significantly decreased compared to baseline values. The levels of MMP-9 (p = 0.024) and MMP-2 (p < 0.01) were significantly increased compared to baseline values. In addition to the effective blood pressure reduction in response to RSD, this study demonstrates a positive effect of RSD on biomarkers reflecting vascular inflammation and remodeling. These results suggest a possible prognostic benefit of RSD in high-risk patients for endothelial dysfunction and cardiovascular remodeling as well as end-organ damage.

Simultaneous determination of osthole, bergapten and isopimpinellin in rat plasma and tissues by liquid chromatography-tandem mass spectrometry.

PubMed

Li, Jing; Ma, Bo; Zhang, Qi; Yang, Xiaojing; Sun, Jingjing; Tang, Bowen; Cui, Guangbo; Yao, Di; Liu, Lei; Gu, Guiying; Zhu, Jianwei; Wei, Ping; Ouyang, Pingkai

2014-11-01

A highly selective and sensitive method for simultaneous quantitation of osthole, bergapten and isopimpinellin in rat plasma and tissues was developed by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). After liquid-liquid extraction of samples with methyl tert-butyl ether, the analytes and dextrorphan (internal standard, IS) were separated by a Hypersil GOLD AQ C18 column with gradient elution of acetonitrile and water containing 0.5‰ formic acid. Three determinands were detected using an electrospray ionization (ESI) tandem mass spectrometry in the multiple reaction monitoring (MRM) modes with positive electrospray ionization. Calibration curves were recovered over the concentration ranges of 1-200 ng/ml, 1-500 ng/ml, 0.25-200 ng/ml for osthole, bergapten and isopimpinellin in plasma; 1-100 ng/ml, 1-500 ng/ml, 0.5-100 ng/ml for osthole, bergapten and isopimpinellin in tissues, respectively. The intra-day precision (R.S.D.) was within 13.90% and the intra-day accuracy (R.E.) was within -6.27 to 6.84% in all biological matrixes. The inter-day precision (R.S.D.) was less than 13.66% and the inter-day accuracy (R.E.) was within -10.64 to 13.04%. Then the method was successfully applied to investigate plasma pharmacokinetic study and tissue distribution of osthole, bergapten and isopimpinellin in rats after oral administration of Fructus Cnidii extraction, especially for testis/uterus tissue distribution. The results demonstrated that osthole, bergapten and isopimpinellin were absorbed and eliminated rapidly with wide distributions in rats. Distribution data of these three bioactive components in testis/uterus tissues could offer useful information for the further preclinical and clinical studies of Fructus Cnidii in the treatment of genital system disease. Copyright © 2014 Elsevier B.V. All rights reserved.

Modification of a commercial gas chromatography isotope ratio mass spectrometer for on-line carbon isotope dilution: Evaluation of its analytical characteristics for the quantification of organic compounds.

PubMed

Alonso Sobrado, Laura; Robledo Fernández, Mario; Cueto Díaz, Sergio; Ruiz Encinar, Jorge; García Alonso, J Ignacio

2015-11-06

We describe the instrumental modification of a commercial gas chromatography isotope ratio mass spectrometer (GC-IRMS) and its application for on-line carbon isotope dilution. The main modification consisted in the addition of a constant flow of enriched (13)CO2 diluted in helium after the chromatographic column through the splitter holder located inside the chromatographic oven of the instrument. In addition, and in contrast to the conventional mode of operation of GC-IRMS instruments where the signal at m/z 45 is amplified 100-fold with respect to the signal at m/z 44, the same signal amplification was used in both Faraday cups at m/z 44 and 45. Under these conditions isotope ratio precision for the ratio 44/45 was around 0.05% RSD (n=50). The evaluation of the instrument was performed with mixtures of organic compounds including 11 n-alkanes, 16 PAHs, 12 PCBs and 3 benzothiophenes. It was observed that compounds of very different boiling points could be analysed without discrimination in the injector when a Programmable Temperature Vaporizer (PTV) injector was employed. Moreover, the presence of heteroatoms (Cl or S) in the structure of the organic compounds did not affect their combustion efficiency and therefore the trueness of the results. Quantitative results obtained for all the analytes assayed were excellent in terms of precision (<3% RSD) and accuracy (average relative error≤4%) and what is more important using a single and simple generic internal standard for quantification. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Green Quantification Strategy Combined with Chemometric Analysis for Triglycerides in Seeds Used in Traditional Chinese Medicine.

PubMed

Hou, Jin-Jun; Guo, Ji-Ling; Cao, Chun-Mei; Yao, Shuai; Long, Hua-Li; Cai, Lu-Ying; Da, Juan; Wu, Wan-Ying; Guo, De-An

2018-04-01

Triglycerides are the primary constituents of some seed kernels used in traditional Chinese medicine. Quality control of seed kernels containing multiple components with an environmentally friendly method is indispensable for establishing their quality standards (called monographs) in pharmacopeia. Using coix seeds (Semen Coicis) as an example, a green quantification strategy was proposed by combining C 8 core-shell particles with single standard to determine multicomponent technologies to quantify seven triglycerides simultaneously. A core-shell column, namely, Halo C 8 (3.0 × 100 mm, 2.7 µm), was used. Methanol was used as the mobile phase at a flow rate of 0.3 mL/min, enabling UV detection of the elutes. Seven triglycerides were well separated in 20 min, and simultaneously quantified using triolein as a single standard. The conversion factor for each standard was set as 1.0 on ELSD, while for the conversion factors at 203 nm, the values increased with the reduction of linoleate. The recovery values were all in the range of 97 - 107% (RSD < 3.0%). The RSD values of precision, including intraday and intermediate precision, were < 3.0% when the total content of triglycerides was calculated. The linearity reached r ≥ 0.9990, and the limit of quantitation reached 40 - 70 ng. Forty-nine batches of coix seeds from four different places of origins and eight batches of adulterants were evaluated and differentiated using principal component analysis. In addition, the validated method was used successfully to quantity seven triglycerides in Semen Persicae, Semen Armeniacae Amarum, and Semen Pruni. Georg Thieme Verlag KG Stuttgart · New York.

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.

Development, Optimization, and Validation of a Microplate Bioassay for Relative Potency Determination of Linezolid Using a Design Space Concept, and its Measurement Uncertainty.

PubMed

Saviano, Alessandro Morais; Francisco, Fabiane Lacerda; Ostronoff, Celina Silva; Lourenço, Felipe Rebello

2015-01-01

The aim of this study was to develop, optimize, and validate a microplate bioassay for relative potency determination of linezolid in pharmaceutical samples using quality-by-design and design space approaches. In addition, a procedure is described for estimating relative potency uncertainty based on microbiological response variability. The influence of culture media composition was studied using a factorial design and a central composite design was adopted to study the influence of inoculum proportion and triphenyltetrazolium chloride in microbial growth. The microplate bioassay was optimized regarding the responses of low, medium, and high doses of linezolid, negative and positive controls, and the slope, intercept, and correlation coefficient of dose-response curves. According to optimization results, design space ranges were established using: (a) low (1.0 μg/mL), medium (2.0 μg/mL), and high (4.0 μg/mL) doses of pharmaceutical samples and linezolid chemical reference substance; (b) Staphylococcus aureus ATCC 653 in an inoculum proportion of 10%; (c) antibiotic No. 3 culture medium pH 7.0±0.1; (d) 6 h incubation at 37.0±0.1ºC; and (e) addition of 50 μL of 0.5% (w/v) triphenyltetrazolium chloride solution. The microplate bioassay was linear (r2=0.992), specific, precise (repeatability RSD=2.3% and intermediate precision RSD=4.3%), accurate (mean recovery=101.4%), and robust. The overall measurement uncertainty was reasonable considering the increased variability inherent in microbiological response. Final uncertainty was comparable with those obtained with other microbiological assays, as well as chemical methods.

The extended Baryon Oscillation Spectroscopic Survey: a cosmological forecast

NASA Astrophysics Data System (ADS)

Zhao, Gong-Bo; Wang, Yuting; Ross, Ashley J.; Shandera, Sarah; Percival, Will J.; Dawson, Kyle S.; Kneib, Jean-Paul; Myers, Adam D.; Brownstein, Joel R.; Comparat, Johan; Delubac, Timothée; Gao, Pengyuan; Hojjati, Alireza; Koyama, Kazuya; McBride, Cameron K.; Meza, Andrés; Newman, Jeffrey A.; Palanque-Delabrouille, Nathalie; Pogosian, Levon; Prada, Francisco; Rossi, Graziano; Schneider, Donald P.; Seo, Hee-Jong; Tao, Charling; Wang, Dandan; Yèche, Christophe; Zhang, Hanyu; Zhang, Yuecheng; Zhou, Xu; Zhu, Fangzhou; Zou, Hu

2016-04-01

We present a science forecast for the extended Baryon Oscillation Spectroscopic Survey (eBOSS) survey. Focusing on discrete tracers, we forecast the expected accuracy of the baryonic acoustic oscillation (BAO), the redshift-space distortion (RSD) measurements, the fNL parameter quantifying the primordial non-Gaussianity, the dark energy and modified gravity parameters. We also use the line-of-sight clustering in the Lyman α forest to constrain the total neutrino mass. We find that eBOSS luminous red galaxies, emission line galaxies and clustering quasars can achieve a precision of 1, 2.2 and 1.6 per cent, respectively, for spherically averaged BAO distance measurements. Using the same samples, the constraint on fσ8 is expected to be 2.5, 3.3 and 2.8 per cent, respectively. For primordial non-Gaussianity, eBOSS alone can reach an accuracy of σ(fNL) ˜ 10-15. eBOSS can at most improve the dark energy figure of merit by a factor of 3 for the Chevallier-Polarski-Linder parametrization, and can well constrain three eigenmodes for the general equation-of-state parameter. eBOSS can also significantly improve constraints on modified gravity parameters by providing the RSD information, which is highly complementary to constraints obtained from weak lensing measurements. A principal component analysis shows that eBOSS can measure the eigenmodes of the effective Newton's constant to 2 per cent precision; this is a factor of 10 improvement over that achievable without eBOSS. Finally, we derive the eBOSS constraint (combined with Planck, Dark Energy Survey and BOSS) on the total neutrino mass, σ(Σmν) = 0.03 eV (68 per cent CL), which in principle makes it possible to distinguish between the two scenarios of neutrino mass hierarchies.

Exposure to 4,4'-methylenediphenyl diisocyanate (MDI) during moulding of rigid polyurethane foam: determination of airborne MDI and urinary 4,4'-methylenedianiline (MDA).

PubMed

Kääriä, K; Hirvonen, A; Norppa, H; Piirilä, P; Vainio, H; Rosenberg, C

2001-04-01

Occupational exposure to 4,4'-methylenediphenyl diisocyanate (MDI) was measured during moulding of rigid polyurethane foam. The aim of the study was to find out whether an MDI-derived urinary amine metabolite could be detected in the urine of workers exposed to apparently low levels of MDI. Airborne MDI was sampled on 1-(2-methoxyphenyl)-piperazine (2MP)-impregnated glass fibre filters and determined by high-performance liquid chromatography (HPLC) using ultraviolet (UV) and electrochemical (EC) detection. The limit of detection of MDI was 3 ng ml-1 for a 20 microliters injection. The precision of sample preparation, expressed as relative standard deviation (RSD), was 1.3% with UV detection and 2.1% with EC detection at a concentration of 70 ng MDI ml-1 (n = 6). The 2MP-MDI derivative was stable at +4 degrees C up to eight weeks. The accuracy of the method was validated in an international quality control programme. Workers (n = 57) from three different factories participated in the study. Urinary 4,4'-methylenedianiline (MDA) metabolite was determined after acid hydrolysis as heptafluorobutyric anhydride derivatives by gas chromatography-mass spectrometry using chemical ionisation and monitoring negative ions. The limit of detection in urine was 0.2 nmol l-1. The precision of six analyses for a urine sample spiked to a concentration of 1 nmol l-1 was 29% (RSD). The MDI concentrations were below the limit of detection in most (64%) of the air samples collected in the worker's breathing zone. Still, detectable amounts of MDA were found in 97% of the urine samples. Monitoring of urinary MDA appears to be an appropriate method of assessing MDI exposure in work environments with low or undetectable MDI concentrations in the workplace air.

Gas pressure assisted microliquid-liquid extraction coupled online to direct infusion mass spectrometry: a new automated screening platform for bioanalysis.

PubMed

Raterink, Robert-Jan; Witkam, Yoeri; Vreeken, Rob J; Ramautar, Rawi; Hankemeier, Thomas

2014-10-21

In the field of bioanalysis, there is an increasing demand for miniaturized, automated, robust sample pretreatment procedures that can be easily connected to direct-infusion mass spectrometry (DI-MS) in order to allow the high-throughput screening of drugs and/or their metabolites in complex body fluids like plasma. Liquid-Liquid extraction (LLE) is a common sample pretreatment technique often used for complex aqueous samples in bioanalysis. Despite significant developments that have been made in automated and miniaturized LLE procedures, fully automated LLE techniques allowing high-throughput bioanalytical studies on small-volume samples using direct infusion mass spectrometry, have not been matured yet. Here, we introduce a new fully automated micro-LLE technique based on gas-pressure assisted mixing followed by passive phase separation, coupled online to nanoelectrospray-DI-MS. Our method was characterized by varying the gas flow and its duration through the solvent mixture. For evaluation of the analytical performance, four drugs were spiked to human plasma, resulting in highly acceptable precision (RSD down to 9%) and linearity (R(2) ranging from 0.990 to 0.998). We demonstrate that our new method does not only allow the reliable extraction of analytes from small sample volumes of a few microliters in an automated and high-throughput manner, but also performs comparable or better than conventional offline LLE, in which the handling of small volumes remains challenging. Finally, we demonstrate the applicability of our method for drug screening on dried blood spots showing excellent linearity (R(2) of 0.998) and precision (RSD of 9%). In conclusion, we present the proof of principe of a new high-throughput screening platform for bioanalysis based on a new automated microLLE method, coupled online to a commercially available nano-ESI-DI-MS.

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.

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

Improving quantitative gas chromatography-electron ionization mass spectrometry results using a modified ion source: demonstration for a pharmaceutical application.

PubMed

D'Autry, Ward; Wolfs, Kris; Hoogmartens, Jos; Adams, Erwin; Van Schepdael, Ann

2011-07-01

Gas chromatography-mass spectrometry is a well established analytical technique. However, mass spectrometers with electron ionization sources may suffer from signal drifts, hereby negatively influencing quantitative performance. To demonstrate this phenomenon for a real application, a static headspace-gas chromatography method in combination with electron ionization-quadrupole mass spectrometry was optimized for the determination of residual dichloromethane in coronary stent coatings. Validating the method, the quantitative performance of an original stainless steel ion source was compared to that of a modified ion source. Ion source modification included the application of a gold coating on the repeller and exit plate. Several validation aspects such as limit of detection, limit of quantification, linearity and precision were evaluated using both ion sources. It was found that, as expected, the stainless steel ion source suffered from signal drift. As a consequence, non-linearity and high RSD values for repeated analyses were obtained. An additional experiment was performed to check whether an internal standard compound would lead to better results. It was found that the signal drift patterns of the analyte and internal standard were different, consequently leading to high RSD values for the response factor. With the modified ion source however, a more stable signal was observed resulting in acceptable linearity and precision. Moreover, it was also found that sensitivity improved compared to the stainless steel ion source. Finally, the optimized method with the modified ion source was applied to determine residual dichloromethane in the coating of coronary stents. The solvent was detected but found to be below the limit of quantification. Copyright © 2011 Elsevier B.V. All rights reserved.

Validation of reliable and selective methods for direct determination of glyphosate and aminomethylphosphonic acid in milk and urine using LC-MS/MS.

PubMed

Jensen, Pamela K; Wujcik, Chad E; McGuire, Michelle K; McGuire, Mark A

2016-01-01

Simple high-throughput procedures were developed for the direct analysis of glyphosate [N-(phosphonomethyl)glycine] and aminomethylphosphonic acid (AMPA) in human and bovine milk and human urine matrices. Samples were extracted with an acidified aqueous solution on a high-speed shaker. Stable isotope labeled internal standards were added with the extraction solvent to ensure accurate tracking and quantitation. An additional cleanup procedure using partitioning with methylene chloride was required for milk matrices to minimize the presence of matrix components that can impact the longevity of the analytical column. Both analytes were analyzed directly, without derivatization, by liquid chromatography tandem mass spectrometry using two separate precursor-to-product transitions that ensure and confirm the accuracy of the measured results. Method performance was evaluated during validation through a series of assessments that included linearity, accuracy, precision, selectivity, ionization effects and carryover. Limits of quantitation (LOQ) were determined to be 0.1 and 10 µg/L (ppb) for urine and milk, respectively, for both glyphosate and AMPA. Mean recoveries for all matrices were within 89-107% at three separate fortification levels including the LOQ. Precision for replicates was ≤ 7.4% relative standard deviation (RSD) for milk and ≤ 11.4% RSD for urine across all fortification levels. All human and bovine milk samples used for selectivity and ionization effects assessments were free of any detectable levels of glyphosate and AMPA. Some of the human urine samples contained trace levels of glyphosate and AMPA, which were background subtracted for accuracy assessments. Ionization effects testing showed no significant biases from the matrix. A successful independent external validation was conducted using the more complicated milk matrices to demonstrate method transferability.

Static Scene Statistical Non-Uniformity Correction

DTIC Science & Technology

2015-03-01

Error NUC Non-Uniformity Correction RMSE Root Mean Squared Error RSD Relative Standard Deviation S3NUC Static Scene Statistical Non-Uniformity...Deviation ( RSD ) which normalizes the standard deviation, σ, to the mean estimated value, µ using the equation RS D = σ µ × 100. The RSD plot of the gain...estimates is shown in Figure 4.1(b). The RSD plot shows that after a sample size of approximately 10, the different photocount values and the inclusion

A dosimetric study of cardiac dose sparing using the reverse semi-decubitus technique for left breast and internal mammary chain irradiation.

PubMed

Niglas, Mark; McCann, Claire; Keller, Brian M; Makhani, Nadiya; Presutti, Joseph; Vesprini, Danny; Rakovitch, Eileen; Elzibak, Alyaa; Mashouf, Shahram; Lee, Justin

2016-01-01

Breath-hold techniques can reduce cardiac dose in breast radiotherapy. The reverse semi-decubitus (RSD) technique is an alternative free-breathing method used at our centre. This study compares the dosimetry of free-breathing supine, RSD and moderate deep inspiration breath-hold (mDIBH) techniques. Twelve patients with left-sided breast cancer who were simulated using standard supine, RSD and mDIBH techniques were identified retrospectively. New plans using standard breast tangents and techniques for internal mammary chain (IMC) nodal coverage were assessed. Using standard tangents, mean heart dose, heart V25Gy and mean left anterior descending artery (LAD) dose were found to be significantly lower for RSD and mDIBH when compared to free-breathing supine (p ⩽ 0.03). Using wide-tangents, the maximum LAD point dose was also lower for RSD and mDIBH (p ⩽ 0.02). There were no statistically significant dosimetric differences found between the RSD and mDIBH simulation techniques for standard breast-tangent plans, though organ-at-risk doses were lower for mDIBH in wide-tangent plans. There was no improvement in cardiac dosimetry between RSD and free-breathing supine when using an electron field IMC plan. For patients unable to tolerate breath-hold, the RSD technique is an alternative approach that can reduce cardiac dose. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Structural basis for the sequestration of the anti-σ(70) factor Rsd from σ(70) by the histidine-containing phosphocarrier protein HPr.

PubMed

Park, Young Ha; Um, Si Hyeon; Song, Saemee; Seok, Yeong Jae; Ha, Nam Chul

2015-10-01

Histidine-containing phosphocarrier protein (HPr) is a general component of the bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) involved in the phosphorylation-coupled transport of numerous sugars called PTS sugars. HPr mainly exists in a dephosphorylated form in the presence of PTS sugars in the medium, while its phosphorylation increases in the absence of PTS sugars. A recent study revealed that the dephosphorylated form of HPr binds and antagonizes the function of the antisigma factor Rsd. This anti-sigma factor sequesters the housekeeping sigma factor σ(70) to facilitate switching of the sigma subunit on RNA polymerase from σ(70) to the stress-responsive sigma factor σ(S) in stationary-phase cells. In this study, the structure of the complex of Rsd and HPr was determined at 2.1 Å resolution and revealed that the binding site for HPr on the surface of Rsd partly overlaps with that for σ(70). The localization of the phosphorylation site on HPr at the binding interface for Rsd explains why phosphorylation of HPr abolishes its binding to Rsd. The mutation of crucial residues involved in the HPr-Rsd interaction significantly influenced the competition between HPr and σ(70) for binding to Rsd both in vitro and in vivo. The results provide a structural basis for the linkage of global gene regulation to nutrient availability in the external environment.

Ring-Sheared Drop (RSD): Microgravity Module for Containerless Flow Studies

NASA Astrophysics Data System (ADS)

Gulati, Shreyash; Raghunandan, Aditya; Rasheed, Fayaz; McBride, Samantha A.; Hirsa, Amir H.

2017-02-01

Microgravity is potentially a powerful tool for investigating processes that are sensitive to the presence of solid walls, since fluid containment can be achieved by surface tension. One such process is the transformation of protein in solution into amyloid fibrils; these are protein aggregates associated with neurodegenerative diseases such as Alzheimer's and Parkinson's. In addition to solid walls, experiments with gravity are also subject to influences from sedimentation of aggregates and buoyancy-driven convection. The ring-sheared drop (RSD) module is a flow apparatus currently under development to study formation of amyloid fibrils aboard the International Space Station (ISS). A 25 mm diameter drop of protein solution will be contained by surface tension and constrained by a pair of sharp-edged tubes, forming two contact rings. Shear can be imparted by rotating one ring with the other ring kept stationary. Here we report on parabolic flights conducted to test the growth and pinning of 10 mm diameter drops of water in under 10 s of microgravity. Finite element method (FEM) based fluid dynamics computations using a commercial package (COMSOL) assisted in the design of the parabolic flight experiments. Prior to the parabolic flights, the code was validated against experiments in the lab (1 g), on the growth of sessile and pendant droplets. The simulations show good agreement with the experiments. This modeling capability will enable the development of the RSD at the 25 mm scale for the ISS.

Effect of renal sympathetic denervation on atrial substrate remodeling in ambulatory canines with prolonged atrial pacing.

PubMed

Wang, Xule; Zhao, Qingyan; Huang, He; Tang, Yanhong; Xiao, Jinping; Dai, Zixuan; Yu, Shengbo; Huang, Congxin

2013-01-01

We have previously demonstrated that catheter-based renal sympathetic denervation (RSD) could suppress atrial fibrillation (AF) in canines with short-time rapid right atrial pacing (RAP). However, the role of renal denervation on atrial remodeling is unclear. The aim of the present study was to explore the long-term effect of RSD on the atrial remodeling during prolonged RAP. Twenty mongrel dogs were implanted with a high-frequency cardiac pacemaker with a transvenous lead inserted into the right atrial appendage. The dogs were divided into three groups: a sham-operated group (n = 6), the chronic RAP (CRAP) group (n = 7), and the CRAP+RSD group (n = 7). In the CRAP+RSD group, a pacemaker was implanted 6 weeks after RSD was performed bilaterally for recovery. RAP was maintained for 5 weeks in CRAP group and CRAP+RSD group. The plasma levels of Angiotensin II and aldosterone were significantly increased in CRAP group compared with sham-operated group, but the increasing trend was inhibited in CRAP+RSD group compared with CRAP group (P<0.05). Similarly, RSD suppressed the increasing trend that prolonged RAP produced in the left atrial levels of ANP, TNF-α and IL-6. Compared with the sham-operated group, the CRAP group had significantly increased levels of caspase-3, bax and Cx40 whereas the level of Bcl-2 decreased (P<0.05). RSD markedly reduced the upregulation of caspase-3, bax and Cx40 and the downregulation of Bcl-2 expression compared with the CRAP group (P<0.05). Picric acid-sirius red staining study suggested that RSD could markedly alleviate the lesion degree of cardic fibrosis induced by CRAP (P<0.05). Immunohistochemistry results showed that the densities of TH- and GAP43- positive nerves were significantly elevated in the CRAP group compared with the sham-operated group, while RSD operation signicantly inhibited the these changes produced by CRAP. These findings suggest that renal denervation could suppress the atrial remodeling after prolonged RAP in ambulatory canines.

[Beneficial effects of renal denervation on pulmonary vascular remodeling in experimental pulmonary artery hypertension].

PubMed

Zhang, Shujuan; Zhao, Qingyan; Jiang, Xuejun; Yang, Bo; Dai, Zixuan; Wang, Xiaozhan; Wang, Xule; Guo, Zongwen; Yu, Shengbo; Tang, Yanhong; Hu, Wei; Huang, Congxin

2015-04-14

To explore the effects of renal sympathetic denervation (RSD) on pulmonary vascular remodeling in a model of pulmonary arterial hypertension (PAH). According to the random number table, 24 beagles were randomized into control, PAH and PAH+RSD groups (n=8 each). The levels of neurohormone, echocardiogram and dynamics parameters were measured. Then 0.1 ml/kg dimethylformamide (control group) or 2 mg/kg dehydromonocrotaline (PAH and PAH+RSD groups) were injected. The PAH+RSD group underwent RSD after injection. At week 8 post-injection, the neurohormone levels, echocardiogram, dynamics parameters and pulmonary tissue morphology were observed. The values of right ventricular systolic pressure (RVSP) and pulmonary arterial systolic pressure (PASP) in PAH and PAH+RSD groups were both significantly higher than those in control group ((42.8±8.7), (30.8±6.8) vs (23.2±5.7) mmHg (1 mmHg=0.133 kPa) and (45.1±11.2), (32.6±7.9) vs (24.7±7.1) mmHg). Meanwhile, the values of RVSP and PASP in PAH group were higher than those in PAH+RSD group (all P<0.01). The levels of serum angiotensin II (Ang II) and endothelin-1 significantly increased after 8 weeks in PAH dogs ((228±41) vs (113±34) pg/ml and (135±15) vs (77±7) pg/ml, all P<0.01). And Ang II and endothelin-1 were higher in lung tissues of PAH group ((65±10) and (96±10) pg/ml) than in those of control group ((38±7) and (54±6) pg/ml) and PAH+RSD group ((46±8) and (67±9) pg/ml) (all P<0.01). Pulmonary tissues had marked collagen hyperplasia and lamellar corpuscles of type 2 alveolar cells were damaged more severely in PAH dogs than in PAH+RSD dogs. RSD suppresses pulmonary vascular remodeling and decreases pulmonary arterial pressure in experimental PAH. And the effect of RSD on PAH may contribute to decreased neurohormone levels.

Effect of Renal Sympathetic Denervation on Atrial Substrate Remodeling in Ambulatory Canines with Prolonged Atrial Pacing

PubMed Central

Wang, Xule; Zhao, Qingyan; Huang, He; Tang, Yanhong; Xiao, Jinping; Dai, Zixuan; Yu, Shengbo; Huang, Congxin

2013-01-01

We have previously demonstrated that catheter-based renal sympathetic denervation (RSD) could suppress atrial fibrillation (AF) in canines with short-time rapid right atrial pacing (RAP). However, the role of renal denervation on atrial remodeling is unclear. The aim of the present study was to explore the long-term effect of RSD on the atrial remodeling during prolonged RAP. Twenty mongrel dogs were implanted with a high-frequency cardiac pacemaker with a transvenous lead inserted into the right atrial appendage. The dogs were divided into three groups: a sham-operated group (n = 6), the chronic RAP (CRAP) group (n = 7), and the CRAP+RSD group (n = 7). In the CRAP+RSD group, a pacemaker was implanted 6 weeks after RSD was performed bilaterally for recovery. RAP was maintained for 5 weeks in CRAP group and CRAP+RSD group. The plasma levels of Angiotensin II and aldosterone were significantly increased in CRAP group compared with sham-operated group, but the increasing trend was inhibited in CRAP+RSD group compared with CRAP group (P<0.05). Similarly, RSD suppressed the increasing trend that prolonged RAP produced in the left atrial levels of ANP, TNF-α and IL-6. Compared with the sham-operated group, the CRAP group had significantly increased levels of caspase-3, bax and Cx40 whereas the level of Bcl-2 decreased (P<0.05). RSD markedly reduced the upregulation of caspase-3, bax and Cx40 and the downregulation of Bcl-2 expression compared with the CRAP group (P<0.05). Picric acid–sirius red staining study suggested that RSD could markedly alleviate the lesion degree of cardic fibrosis induced by CRAP (P<0.05). Immunohistochemistry results showed that the densities of TH- and GAP43- positive nerves were significantly elevated in the CRAP group compared with the sham-operated group, while RSD operation signicantly inhibited the these changes produced by CRAP. These findings suggest that renal denervation could suppress the atrial remodeling after prolonged RAP in ambulatory canines. PMID:23724069

Determination of mineral oil aromatic hydrocarbons in edible oils and fats by online liquid chromatography-gas chromatography-flame ionization detection - Evaluation of automated removal strategies for biogenic olefins.

PubMed

Nestola, Marco; Schmidt, Torsten C

2017-07-07

The determination of mineral oil aromatic hydrocarbons (MOAH) in foodstuffs gained in importance over the last years as carcinogenicity cannot be excluded for certain MOAH. The existence of olefins in foodstuffs, such as edible oils and fats, can be problematic for the determination of MOAH by LC-GC-FID. Removal of these interfering substances by HPLC based on polarity differences is not possible. During gas chromatographic separation heavily overloaded peaks are observed rendering the detection of small mineral oil contaminations almost impossible. Therefore, removal of these olefins is necessary before subjection of the sample to LC-GC-FID. Epoxidation of olefins to increase their polarity proved to be a valuable tool in the past. Precision and trueness of the results as shown in a collaborative trial, however, are relying on exact reaction conditions. Additionally, it is known that certain MOAH are oxidized during epoxidation and therefore get lost. In the scope of this work, hydroboration, bromohydrin reaction, and epoxidation were examined for their potential for derivatization of unsaturated hydrocarbons with increased robustness and higher recovery of MOAH. Epoxidation by meta-chloroperoxybenzoic acid (mCPBA) delivered the best removal of olefins. Factors influencing this reaction were enlightened. Adaption of the reaction conditions and time-controlled automation increased the recovery of polycyclic MOAH. Good precision (RSD r <1.5%) and recovery (95-102%) for MOAH were also observed for sunflower and olive oils spiked with a lubricating mineral oil (at 24.5mg/kg of MOAH). The trueness of the method was verified by analyzing collaborative trial samples. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

[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.

Determination of cadmium in sediments by diluted HCI extraction and isotope dilution ICP-MS.

PubMed

Terán-Baamonde, Javier; Soto-Ferreiro, Rosa-María; Carlosena, Alatzne; Andrade, José-Manuel; Prada, Darío

2018-08-15

Isotope dilution ICP-MS is proposed to measure the mass fraction of Cd extracted by diluted HCl in marine sediments, using a fast and simple extraction procedure based on ultrasonic probe agitation. The 111 Cd isotope was added before the extraction to achieve isotope equilibration with native Cd solubilized from the sample. The parameters affecting trueness and precision of isotope ratio measurements were evaluated carefully and subsequently corrected in order to minimize errors; they were: detector dead time, spectral interferences, mass discrimination factor and optimum sample/spike ratio. The mass fraction of Cd extracted was compared with the sum of the certified contents of the three steps of the sequential extraction procedure of the Standards, Measurements and Testing Programme (SM&T) analysing the BCR 701 sediment to validate the method. The certified and measured values agreed, giving a measured / certified mass fraction ratio of 1.05. Further, the extraction procedure itself was studied by adding the enriched isotope after the extraction step, which allowed verifying that analyte losses occurred during this process. Two additional reference sediments with certified total cadmium contents were also analysed. The method provided very good precision (0.9%, RSD) and a low detection limit, 1.8 ng g -1 . The procedural uncertainty budget was estimated following the EURACHEM Guide by means of the 'GUM Workbench' software, obtaining a relative expanded uncertainty of 1.5%. The procedure was applied to determine the bioaccessible mass fraction of Cd in sediments from two environmentally and economically important areas of Galicia (rias of Arousa and Vigo, NW of Spain). Copyright © 2018 Elsevier B.V. All rights reserved.

Design of a compressed air modulator to be used in comprehensive multidimensional gas chromatography and its application in the determination of pesticide residues in grapes.

PubMed

Pizzutti, Ionara R; Vreuls, René J J; de Kok, André; Roehrs, Rafael; Martel, Samile; Friggi, Caroline A; Zanella, Renato

2009-04-10

In this study, a new modulator that is simple, robust and presents low operation costs, was developed. This modulator uses compressed air to cool two small portions in the first centimeters of the second chromatographic column of a comprehensive multidimensional gas chromatography (GCxGC) system. The results show a variation in the peak area less than 3 and 5% to alkanes and pesticides, respectively. The standard deviations for the retention times in the first and second dimension are around 0.05 min and 0.05s for all the compounds. The system was optimized with n-alkanes. The GCxGC system proposed was applied in the determination of pyrethroid pesticides (bifenthrin, cypermethrin, deltamethrin, fenvalerate, esfenvalerate, cis- and trans-permethrin) in grape samples. Samples were extracted by the mini-Luke modified method and pesticides were quantified by comprehensive multidimensional gas chromatography with micro electron-capture detection (microECD). The values of method limit of quantification (LOQ) were 0.01-0.02 mg kg(-1) for all studied pyrethroid and the values of recovery were between 94.3 and 115.2%, with good precision (RSD<18.4%), demonstrating that the performance of the total method consisting of a modified Luke extraction method and determination by GCxGC-microECD are satisfactory. This study also showed that the system using a modulator with a double jet of compressed air has the potential for application in the analysis of a wider range of pesticide residues in other commodities since it provides low values of LOQ with acceptable accuracy and precision.

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 .

A sensitive determination of terbutaline in pharmaceuticals and urine samples using a composite electrode based on zirconium oxide nanoparticles.

PubMed

Baytak, Aysegul Kutluay; Teker, Tugce; Duzmen, Sehriban; Aslanoglu, Mehmet

2016-10-01

An accurate and precise determination of terbutaline has been carried out using a glassy carbon electrode (GCE) modified with a composite of multi-walled carbon nanotubes (MWCNTs) and nanoparticles of zirconium oxide (ZrO2NPs). Energy dispersive X-ray and scanning electron microscopic techniques were utilized for the characterization of the composite layer. Terbutaline exhibited a broad oxidation peak at 770mV on a GCE. However, MWCNTs/GCE presented an electrocatalytic effect toward the oxidation of terbutaline with a better anodic peak at 660mV. Furthermore, the electrochemical behavior of terbutaline has greatly been improved at a GCE modified with a composite of MWCNTs and nanoparticles of ZrO2. The ZrO2NPs/MWCNTs/GCE exhibited a sharp anodic wave at 645mV with a large enhancement of the current response for terbutaline. Square wave voltammetry (SWV) was performed for the determination of terbutaline at ZrO2NPs/MWCNTs/GCE. A linear plot was obtained for the current responses of terbutaline against concentrations in the range of 10-160nM yielding a detection limit of 2.25nM (based on 3Sb/m). Improved voltammetric behavior, long-time stability and good reproducibility were obtained for terbutaline at the proposed electrode. A mean recovery of 101.2% with an RSD% of 1.9 was obtained for the analysis of the drug formulation. The accurate and precise quantification of terbutaline makes the ZrO2NPs/MWCNTs/GCE system of great interest for monitoring its therapeutic use. Copyright © 2016 Elsevier B.V. All rights reserved.

A rapid method for the simultaneous determination of L-ascorbic acid and acetylsalicylic acid in aspirin C effervescent tablet by ultra performance liquid chromatography-tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Wabaidur, Saikh Mohammad; Alothman, Zeid Abdullah; Khan, Mohammad Rizwan

2013-05-01

In present study, a rapid and sensitive method using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the simultaneous determination of L-ascorbic acid and acetylsalicylic acid in aspirin C effervescent tablet. The optimum chromatographic separation was carried out on a reversed phase Waters® Acquity UPLC BEH C18 column (1.7 μm particle size, 100 mm × 2.1 mm ID) with an isocratic elution profile and mobile phase consisting of 0.1% formic acid in water and acetonitrile (75:25, v/v, pH 3.5) at flow rate of 0.5 mL min-1. The influences of mobile phase composition, flow rate and pH on chromatographic resolution were investigated. The total chromatographic analysis time was as short as 2 min with excellent resolution. Detection and quantification of the target compounds were carried out with a triple quadrupole mass spectrometer using negative electrospray ionization (ESI) and multiple reaction monitoring (MRM) modes. The performance of the method was evaluated and very low limits of detection less than 0.09 μg g-1, excellent coefficient correlation (r2 > 0.999) with liner range over a concentration range of 0.1-1.0 μg g-1 for both L-ascorbic acid and acetylsalicylic acid, and good intraday and interday precisions (relative standard deviations (R.S.D.) <3%), were obtained. Comparison of system performance with traditional liquid chromatography-photo diode array detector (HPLC-PDA) was made with respect to analysis time, sensitivity, linearity and precisions. The proposed UPLC-MS/MS method was found to be reproducible and appropriate for quantitative analysis of L-ascorbic acid and acetylsalicylic acid in aspirin C effervescent tablet.

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.

Handgrip strength deficits best explain limitations in performing bimanual activities after stroke.

PubMed

Basílio, Marluce Lopes; de Faria-Fortini, Iza; Polese, Janaine Cunha; Scianni, Aline A; Faria, Christina Dcm; Teixeira-Salmela, Luci Fuscaldi

2016-04-01

[Purpose] To evaluate the relationships between residual strength deficits (RSD) of the upper limb muscles and the performance in bimanual activities and to determine which muscular group would best explain the performance in bimanual activities of chronic stroke individuals. [Subjects and Methods] Strength measures of handgrip, wrist extensor, elbow flexor/extensor, and shoulder flexor muscles of 107 subjects were obtained and expressed as RSD. The performance in bimanual activities was assessed by the ABILHAND questionnaire. [Results] The correlations between the RSD of handgrip and wrist extensor muscles with the ABILHAND scores were negative and moderate, whereas those with the elbow flexor/extensor and shoulder flexor muscles were negative and low. Regression analysis showed that the RSD of handgrip and wrist extensor muscles explained 38% of the variance in the ABILHAND scores. Handgrip RSD alone explained 33% of the variance. [Conclusion] The RSD of the upper limb muscles were negatively associated with the performance in bimanual activities and the RSD of handgrip muscles were the most relevant variable. It is possible that stroke subjects would benefit from interventions aiming at improving handgrip strength, when the goal is to increase the performance in bimanual activities.

Influence of Renal Sympathetic Denervation on Cardiac Extracellular Matrix Turnover and Cardiac Fibrosis.

PubMed

Dörr, Oliver; Liebetrau, Christoph; Möllmann, Helge; Gaede, Luise; Troidl, Christian; Morczeck, Kareen; Wiebe, Jens; Hoffmann, Jedrzej; Voss, Sandra; Bauer, Timm; Hamm, Christian; Nef, Holger

2015-10-01

Renal sympathetic denervation (RSD) represents an effective treatment option for patients with resistant arterial hypertension (HT). Extracellular matrix (ECM) turnover and deposition are essential processes in HT-related cardiovascular remodeling, fibrosis, and cardiac hypertrophy and contribute to hypertensive heart disease. The primary aim of the present study was to examine the effect of RSD on increased collagen turnover as reflected by serum levels of amino-terminal pro-peptides (PINP, PIIINP) and a carboxyl-terminal pro-peptide (PICP), specific biomarkers for cardiac ECM turnover and cardiovascular fibrosis. A total of 100 consecutive patients (mean age: 65.9±10.1 years) undergoing RSD were included in this study. A therapeutic response was defined as an office systolic blood pressure (SBP) reduction of >10mm Hg 6 months after RSD. Venous serum samples for measurement of PICP, PINP, and PIIINP were collected prior to and 6 months after RSD. A significant reduction in the office SBP of 24.3 mm Hg (SBP baseline: 166.9±14.3 mm Hg (P < 0.001) was documented 6 months after RSD. At this time point, the serum levels of PICP, PINP, and PIIINP (P < 0.01) were significantly decreased compared to baseline values in patients with an increased collagen turnover, showing significant differences comparing BP responders and nonresponders. In addition to the effective blood pressure reduction in response to RSD, this study demonstrates a positive effect of RSD on biomarkers reflecting cardiovascular ECM turnover and deposition. These results suggest a beneficial effect of RSD on cardiovascular fibrosis, hypertensive heart disease, and end-organ damage in high-risk patients. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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.

Long-term verification of functional and structural renal damage after renal sympathetic denervation.

PubMed

Dörr, Oliver; Liebetrau, Christoph; Möllmann, Helge; Gaede, Luise; Troidl, Christian; Wiebe, Jens; Renker, Matthias; Bauer, Timm; Hamm, Christian; Nef, Holger

2016-06-01

Previous studies of renal sympathetic denervation (RSD) excluded patients with impaired renal function to avoid potential RSD-related renal damage. Measurement of the highly sensitive biomarkers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) has shown that RSD does not aggravate renal damage during the early post-procedural period. The aim of the present study was to examine the effect of RSD on blood pressure (BP) reduction and renal function after a long-term follow-up. A total of 62 consecutive patients undergoing RSD were included in this study. Serum NGAL and KIM-1 were collected prior to RSD and at 24 hr, 48 hr, and 3 months after RSD. BP measurements, antihypertensive medication use, and safety events were followed over a three-year period. Follow-up data were available over 36.9[±3.4] months in 47 of 62 (75.8%) of the initially included patients. At this time point a significant systolic BP reduction of 23 mm Hg (P > 0.001) was documented, and there were no significant changes in serum creatinine (P = 0.14), blood urea nitrogen (P = 0.33), or estimated glomerular filtration rate (eGFR) (P = 0.2) values. There were also no significant changes documented in patients with impaired renal function (eGFR < 45 mL/min) during the early post- procedural period or the long-term follow-up (P = 0.34). The results of the present study show a sustained effect of RSD on BP reduction after a three-year follow-up, and there was no evidence of renal failure. These results provide verification of the long-term safety and effectiveness of RSD, even in patients with impaired renal function. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

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

Pulmonary vein isolation alone and combined with renal sympathetic denervation in chronic kidney disease patients with refractory atrial fibrillation.

PubMed

Kiuchi, Márcio G; Chen, Shaojie; E Silva, Gustavo R; Paz, Luis M R; Kiuchi, Tetsuaki; de Paula Filho, Ary G; Souto, Gladyston L L

2016-12-01

Atrial fibrillation (AF) commonly occurs in association with chronic kidney disease (CKD), resulting in adverse outcomes. Combining pulmonary vein isolation (PVI) and renal sympathetic denervation (RSD) may reduce the recurrence of AF in patients with CKD and hypertension. We considered that RSD could reduce the recurrence of AF in patients with CKD by modulating sympathetic hyperactivity. Our goal was to compare the impact of PVI + RSD with that of PVI alone in patients with concurrent AF and CKD. This was a single-center, prospective, longitudinal, randomized, double-blind study. Forty-five patients with controlled hypertension, symptomatic paroxysmal AF and/or persistent AF, stage 2 or 3 CKD, and a dual-chamber pacemaker were enrolled from January 2014 to January 2015. We assessed the 30-second recurrence of AF recorded by the pacemaker, 24-hour ambulatory blood pressure measurements, estimated glomerular filtration rate, albuminuria, echocardiographic parameters, and safety of RSD. No patient developed procedural or other complications. The ambulatory blood pressure measurements did not differ within the PVI + RSD group or between the PVI + RSD and PVI groups throughout the study. Significantly more patients in the PVI + RSD group than in the PVI group were free of AF at the 12-month follow-up evaluation. The PVI group had an unacceptable response to ablation with respect to changes in echocardiographic parameters, whereas these parameters improved in the PVI + RSD group. PVI + RSD were associated with a lower AF recurrence rate than PVI alone; it also improved renal function and some echocardiographic parameters. These encouraging data will serve as baseline information for further long-term studies on larger patient populations.

Renal sympathetic denervation modulates ventricular electrophysiology and has a protective effect on ischaemia-induced ventricular arrhythmia.

PubMed

Huang, Bing; Yu, Lilei; He, Bo; Lu, Zhibing; Wang, Songyun; He, Wenbo; Yang, Kang; Liao, Kai; Zhang, Ling; Jiang, Hong

2014-11-01

Recently, a beneficial effect of renal sympathetic denervation (RSD) has been seen in patients with ventricular electrical storm. However, the effect of RSD on ventricular electrophysiology remains unclear. Thirty-three mongrel dogs were included in the present study. Renal sympathetic denervation was performed by radiofrequency ablation of the adventitial surface of the renal artery. In group 1 (n = 8), programmed stimulation was performed before and after RSD to determine the ventricular effective refractory period (ERP) and action potential duration (APD) restitution properties. The same parameters were measured in five other animals that underwent sham RSD to serve as controls. In group 2 (n = 10), acute myocardial ischaemia (AMI) was induced by ligating the proximal left anterior descending coronary artery after the performance of RSD, and the incidence of ventricular arrhythmia (VA) was calculated during 1 h of recording. In another 10 dogs (group 3), AMI was induced and VA was measured with sham RSD. In group 1, RSD significantly prolonged ventricular ERP and APD, reduced the maximal slope (Smax) of the restitution curve and suppressed APD alternans at each site. Renal sympathetic denervation also significantly decreased the spatial dispersion of ERP, APD and Smax. In the five control animals, no significant electrophysiological change was detected after sham RSD. The occurrence of spontaneous VA during 1 h of AMI in group 2 was significantly lower than that in group 3. These data suggest that RSD stabilizes ventricular electrophysiological properties in normal hearts and reduces the occurrence of VA in hearts experiencing AMI. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

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.

Prevention and control of emergent infectious disease with high specific antigen sensor.

PubMed

Zhang, Hongzhe; Zhang, Shanshan; Liu, Nan

2017-11-01

This study aims to evaluate the application of a new type of high specificity antigen sensor in detecting the viruses in sudden infectious diseases. Influenza A (H1N1) virus immunosensor was used for the respective determination of the six kinds of antigens of H1N1, H3N2 viral protein, HA protein of H7N9, influenza B virus, adenovirus, and EV71 virus of same dilution degree on the Screen Printed Carbon Electrode (SPCE), so as to test the specificity of the detection method. In addition, various batches of chick embryo allantoic saliva dilution simulation samples were also detected on their recovery (accuracy), repeatability (precision), and stability. The results were as follows: the linear equation was y = 121.33x + 168; the slope of the linear equation was 121.33 nA/HA unit, representing the sensitivity; correlation coefficient was R 2 =0.9921 > 0.90. Using Statistical Analysis System (SAS) software, we found that: the W values of seven sets of data after Shapiro-Wilk detection were 0.853, 0.991, 0.901, 0.906, 0.825, 0.974, and 0.992, respectively; P values were 0.247, 0.831, 0.386, 0.405, 0.174, 0.691, and 0.821, respectively, all of which were greater than 0.05, suggesting that normality was met. The results of homogeneity test for variance were as follows: F = 2.44, P = 0.0775 > 0.05, suggesting that homogeneity of variance was met. The parametric test results were as follows: F = 19114.0, P < 0.0001, suggesting that there were obvious differences between testing data of the seven groups. The determination recovery rate of electrochemical immunosensor was 80-110%. Relative Standard Deviation (RSD) values of repeatability (precision) test of H1N1 influenza virus electrochemical immunosensor were 7.74%, 3.54%, and 2.01%, all of which were smaller than 10%. The signal response of H1N1 electrochemical immune biological sensor could still maintain more than 85% of the original signal within 30 days of storage. In conclusion, H1N1 electrochemical immune biosensor has good specificity and the test results are not affected by other viruses of the same type. Besides, it has good accuracy which can realize the accurate determination of A (H1N1) influenza virus in actual detection. Thus, the requirement of precision measurement of A (H1N1) flu virus detection can be met. Therefore, H1N1 electrochemical immune biosensors can be used in actual detection with good stability.

Mass spectrometry of Escherichia coli RNA polymerase: interactions of the core enzyme with sigma70 and Rsd protein.

PubMed

Ilag, Leopold L; Westblade, Lars F; Deshayes, Caroline; Kolb, Annie; Busby, Stephen J W; Robinson, Carol V

2004-02-01

The E. coli RNA polymerase core enzyme is a multisubunit complex of 388,981 Da. To initiate transcription at promoters, the core enzyme associates with a sigma subunit to form holo RNA polymerase. Here we have used nanoflow electrospray mass spectrometry, coupled with tandem mass spectrometry, to probe the interaction of the RNA polymerase core enzyme with the most abundant sigma factor, sigma70. The results show remarkably well-resolved spectra for both the core and holo RNA polymerases. The regulator of sigma70, Rsd protein, has previously been identified as a protein that binds to free sigma70. We show that Rsd also interacts with core enzyme. In addition, by adding increasing amounts of Rsd, we show that sigma70 is displaced from holo RNA polymerase, resulting in complexes of Rsd with core and sigma70. The results argue for a model in which Rsd not only sequesters sigma70, but is also an effector of core RNA polymerase.

HPr antagonizes the anti-σ70 activity of Rsd in Escherichia coli.

PubMed

Park, Young-Ha; Lee, Chang-Ro; Choe, Mangyu; Seok, Yeong-Jae

2013-12-24

The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) is a multicomponent system that participates in a variety of physiological processes in addition to the phosphorylation-coupled transport of numerous sugars. In Escherichia coli and other enteric bacteria, enzyme IIA(Glc) (EIIA(Glc)) is known as the central processing unit of carbon metabolism and plays multiple roles, including regulation of adenylyl cyclase, the fermentation/respiration switch protein FrsA, glycerol kinase, and several non-PTS transporters, whereas the only known regulatory role of the E. coli histidine-containing phosphocarrier protein HPr is in the activation of glycogen phosphorylase. Because HPr is known to be more abundant than EIIA(Glc) in enteric bacteria, we assumed that there might be more regulatory mechanisms connected with HPr. The ligand fishing experiment in this study identified Rsd, an anti-sigma factor known to complex with σ(70) in stationary-phase cells, as an HPr-binding protein in E. coli. Only the dephosphorylated form of HPr formed a tight complex with Rsd and thereby inhibited complex formation between Rsd and σ(70). Dephosphorylated HPr, but not phosphorylated HPr, antagonized the inhibitory effect of Rsd on σ(70)-dependent transcriptions both in vivo and in vitro, and also influenced the competition between σ(70) and σ(S) for core RNA polymerase in the presence of Rsd. Based on these data, we propose that the anti-σ(70) activity of Rsd is regulated by the phosphorylation state-dependent interaction of HPr with Rsd.

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.

Complex regional pain syndrome type I (RSD): pathology of skeletal muscle and peripheral nerve.

PubMed

van der Laan, L; ter Laak, H J; Gabreëls-Festen, A; Gabreëls, F; Goris, R J

1998-07-01

Reflex sympathetic dystrophy (RSD) (recently reclassified as complex regional pain syndrome type I) is a syndrome occurring in extremities and, when chronic, results in severe disability and untractable pain. RSD may be accompanied by neurologic symptoms even when there is no previous neurologic lesion. There is no consensus as to the pathogenic mechanism involved in RSD. To gain insight into the pathophysiology of RSD, we studied histopathology of skeletal muscle and peripheral nerve from patients with chronic RSD in a lower extremity. In eight patients with chronic RSD, an above-the-knee amputation was performed because of a nonfunctional limb. Specimens of sural nerves, tibial nerves, common peroneal nerves, gastrocnemius muscles, and soleus muscles were obtained from the amputated legs and analyzed by light and electron microscopy. In all patients, the affected leg showed similar neurologic symptoms such as spontaneous pain, hyperpathy, allodynia, paresis, and anesthesia dolorosa. The nerves showed no consistent abnormalities of myelinated fibers. In four patients, the C-fibers showed electron microscopic pathology. In all patients, the gastrocnemius and soleus muscle specimens showed a decrease of type I fibers, an increase of lipofuscin pigment, atrophic fibers, and severely thickened basal membrane layers of the capillaries. In chronic RSD, efferent nerve fibers were histologically unaffected; from afferent fibers, only C-fibers showed histopathologic abnormalities. Skeletal muscle showed a variety of histopathologic findings, which are similar to the histologic abnormalities found in muscles of patients with diabetes.

HPr antagonizes the anti-σ70 activity of Rsd in Escherichia coli

PubMed Central

Park, Young-Ha; Lee, Chang-Ro; Choe, Mangyu; Seok, Yeong-Jae

2013-01-01

The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) is a multicomponent system that participates in a variety of physiological processes in addition to the phosphorylation-coupled transport of numerous sugars. In Escherichia coli and other enteric bacteria, enzyme IIAGlc (EIIAGlc) is known as the central processing unit of carbon metabolism and plays multiple roles, including regulation of adenylyl cyclase, the fermentation/respiration switch protein FrsA, glycerol kinase, and several non-PTS transporters, whereas the only known regulatory role of the E. coli histidine-containing phosphocarrier protein HPr is in the activation of glycogen phosphorylase. Because HPr is known to be more abundant than EIIAGlc in enteric bacteria, we assumed that there might be more regulatory mechanisms connected with HPr. The ligand fishing experiment in this study identified Rsd, an anti-sigma factor known to complex with σ70 in stationary-phase cells, as an HPr-binding protein in E. coli. Only the dephosphorylated form of HPr formed a tight complex with Rsd and thereby inhibited complex formation between Rsd and σ70. Dephosphorylated HPr, but not phosphorylated HPr, antagonized the inhibitory effect of Rsd on σ70-dependent transcriptions both in vivo and in vitro, and also influenced the competition between σ70 and σS for core RNA polymerase in the presence of Rsd. Based on these data, we propose that the anti-σ70 activity of Rsd is regulated by the phosphorylation state-dependent interaction of HPr with Rsd. PMID:24324139

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

Ultra low-level measurements of actinides by sector field ICP-MS.

PubMed

Pointurier, F; Baglan, N; Hémet, P

2004-01-01

In the present work, a double-focusing sector field inductively coupled plasma-mass spectrometer was optimised for ultra trace and isotopic analyses of actinide long-lived isotopes in low concentration solutions of the fgml(-1) to the ngml(-1) range. Sensitivities of about 3GHz/(microgml(-1)), with as low a background as 0.1cps, were obtained for U using a conventional concentric pneumatic nebuliser. Detection limits are below the fg range for 239Pu and 240Pu. With natural U, a precision lower than 0.5% RSD is currently obtained for 235U/238U isotopic ratio at the 200pgml(-1) level.

Determination of the Cryolite Ratio of KF-NaF-AlF3 Electrolyte by Conductivity Method

NASA Astrophysics Data System (ADS)

Yan, Hengwei; Yang, Jianhong; Liu, Zhanwei; Wang, Chengzhi; Ma, Wenhui

2018-05-01

The cryolite ratio (CR) is an important parameter for the electrolyte in aluminum reduction cells. The measurement method for the CR of the KF-NaF-AlF3 system acid (CR < 3) electrolyte by means of electrical conductivity was initially developed, and the formula for calculating the CR was deduced. This method has the advantages of simple operation and high precision. In addition, the relative standard deviations (RSD) of the measurement are < 1.2 pct, and the analysis error of the NaF or KF content has little effect on the determination of the CR.

Endomembrane-associated RSD-3 is important for RNAi induced by extracellular silencing RNA in both somatic and germ cells of Caenorhabditis elegans

PubMed Central

Imae, Rieko; Dejima, Katsufumi; Kage-Nakadai, Eriko; Arai, Hiroyuki; Mitani, Shohei

2016-01-01

RNA silencing signals in C. elegans spread among cells, leading to RNAi throughout the body. During systemic spread of RNAi, membrane trafficking is thought to play important roles. Here, we show that RNAi Spreading Defective-3 (rsd-3), which encodes a homolog of epsinR, a conserved ENTH (epsin N-terminal homology) domain protein, generally participates in cellular uptake of silencing RNA. RSD-3 is previously thought to be involved in systemic RNAi only in germ cells, but we isolated several deletion alleles of rsd-3, and found that these mutants are defective in the spread of silencing RNA not only into germ cells but also into somatic cells. RSD-3 is ubiquitously expressed, and intracellularly localized to the trans-Golgi network (TGN) and endosomes. Tissue-specific rescue experiments indicate that RSD-3 is required for importing silencing RNA into cells rather than exporting from cells. Structure/function analysis showed that the ENTH domain alone is sufficient, and membrane association of the ENTH domain is required, for RSD-3 function in systemic RNAi. Our results suggest that endomembrane trafficking through the TGN and endosomes generally plays an important role in cellular uptake of silencing RNA. PMID:27306325

Endomembrane-associated RSD-3 is important for RNAi induced by extracellular silencing RNA in both somatic and germ cells of Caenorhabditis elegans.

PubMed

Imae, Rieko; Dejima, Katsufumi; Kage-Nakadai, Eriko; Arai, Hiroyuki; Mitani, Shohei

2016-06-16

RNA silencing signals in C. elegans spread among cells, leading to RNAi throughout the body. During systemic spread of RNAi, membrane trafficking is thought to play important roles. Here, we show that RNAi Spreading Defective-3 (rsd-3), which encodes a homolog of epsinR, a conserved ENTH (epsin N-terminal homology) domain protein, generally participates in cellular uptake of silencing RNA. RSD-3 is previously thought to be involved in systemic RNAi only in germ cells, but we isolated several deletion alleles of rsd-3, and found that these mutants are defective in the spread of silencing RNA not only into germ cells but also into somatic cells. RSD-3 is ubiquitously expressed, and intracellularly localized to the trans-Golgi network (TGN) and endosomes. Tissue-specific rescue experiments indicate that RSD-3 is required for importing silencing RNA into cells rather than exporting from cells. Structure/function analysis showed that the ENTH domain alone is sufficient, and membrane association of the ENTH domain is required, for RSD-3 function in systemic RNAi. Our results suggest that endomembrane trafficking through the TGN and endosomes generally plays an important role in cellular uptake of silencing RNA.

Renal sympathetic denervation inhibits the development of left ventricular mechanical dyssynchrony during the progression of heart failure in dogs.

PubMed

Hu, Wei; Zhao, Qing-yan; Yu, Sheng-bo; Sun, Bin; Chen, Liao; Cao, Sheng; Guo, Rui-qiang

2014-11-22

The purpose of this study was to investigate whether transcatheter renal sympathetic denervation (RSD) interfere with the development of left ventricular (LV) mechanical dyssynchrony during the progression of heart failure (HF). Nineteen beagles were randomly divided into sham-operated group (six dogs), control group (seven dogs), and RSD group (six dogs). Sham-operated group were implanted with pacemakers without pacing; Control group were implanted with pacemakers and underwent 3 weeks of rapid right ventricular pacing; and RSD group underwent catheter-based RSD bilaterally and were simultaneously implanted with pacemakers. Both LV strain and LV dyssynchrony were analyzed via 2D speckle-tracking strain echocardiography to evaluate LV function. Longitudinal dyssynchrony was determined as the standard deviation for time-to-peak speckle-tracking strain on apical 4- and 2-chamber views. Radial and circumferential dyssynchrony was determined as the standard deviation for time-to-peak speckle-tracking strain in mid- and base-LV short-axis views. Each myocardial function was also evaluated by averaging the peak systolic strains. LV systolic pressure (LVSP) and LV end-diastolic pressure (LVEDP) were measured. The LV interstitial fibrosis was determined by histological analysis. Plasma angiotensin II (Ang II), aldosterone and norepinephrine (NE) levels were also measured. After 3 weeks, all of the dogs in both the control and RSD groups showed greater LV end-diastolic volume compared with the sham-operated group; however, the dogs in the RSD group had a higher LV ejection fraction (LVEF) than the dogs in the control group (p<0.001). The LV systolic strains were higher in the RSD group than in the control group (p<0.001 for longitudinal, circumferential and radial strain, respectively). The levels of LV dyssynchrony were lower in the RSD group than in the control group (p<0.001 for longitudinal, circumferential and radial dyssynchrony, respectively). Compared with dogs with control alone, RSD dogs had lower LV end-diastolic pressures and less fibrous tissue. The levels of plasma Ang II, aldosterone and NE were lower in the RSD group than in the control group. RSD inhibites the development of left ventricular mechanical dyssynchrony during the progression of heart failure in dogs.

Stress-induced recruitment of bone marrow-derived monocytes to the brain promotes anxiety-like behavior.

PubMed

Wohleb, Eric S; Powell, Nicole D; Godbout, Jonathan P; Sheridan, John F

2013-08-21

Social stress is associated with altered immunity and higher incidence of anxiety-related disorders. Repeated social defeat (RSD) is a murine stressor that primes peripheral myeloid cells, activates microglia, and induces anxiety-like behavior. Here we show that RSD-induced anxiety-like behavior corresponded with an exposure-dependent increase in circulating monocytes (CD11b(+)/SSC(lo)/Ly6C(hi)) and brain macrophages (CD11b(+)/SSC(lo)/CD45(hi)). Moreover, RSD-induced anxiety-like behavior corresponded with brain region-dependent cytokine and chemokine responses involved with myeloid cell recruitment. Next, LysM-GFP(+) and GFP(+) bone marrow (BM)-chimeric mice were used to determine the neuroanatomical distribution of peripheral myeloid cells recruited to the brain during RSD. LysM-GFP(+) mice showed that RSD increased recruitment of GFP(+) macrophages to the brain and increased their presence within the perivascular space (PVS). In addition, RSD promoted recruitment of GFP(+) macrophages into the PVS and parenchyma of the prefrontal cortex, amygdala, and hippocampus of GFP(+) BM-chimeric mice. Furthermore, mice deficient in chemokine receptors associated with monocyte trafficking [chemokine receptor-2 knockout (CCR2(KO)) or fractalkine receptor knockout (CX3CR1(KO))] failed to recruit macrophages to the brain and did not develop anxiety-like behavior following RSD. Last, RSD-induced macrophage trafficking was prevented in BM-chimeric mice generated with CCR2(KO) or CX3CR1(KO) donor cells. These findings indicate that monocyte recruitment to the brain in response to social stress represents a novel cellular mechanism that contributes to the development of anxiety.

Stress-Induced Recruitment of Bone Marrow-Derived Monocytes to the Brain Promotes Anxiety-Like Behavior

PubMed Central

Wohleb, Eric S.; Powell, Nicole D.

2013-01-01

Social stress is associated with altered immunity and higher incidence of anxiety-related disorders. Repeated social defeat (RSD) is a murine stressor that primes peripheral myeloid cells, activates microglia, and induces anxiety-like behavior. Here we show that RSD-induced anxiety-like behavior corresponded with an exposure-dependent increase in circulating monocytes (CD11b+/SSClo/Ly6Chi) and brain macrophages (CD11b+/SSClo/CD45hi). Moreover, RSD-induced anxiety-like behavior corresponded with brain region-dependent cytokine and chemokine responses involved with myeloid cell recruitment. Next, LysM-GFP+ and GFP+ bone marrow (BM)-chimeric mice were used to determine the neuroanatomical distribution of peripheral myeloid cells recruited to the brain during RSD. LysM-GFP+ mice showed that RSD increased recruitment of GFP+ macrophages to the brain and increased their presence within the perivascular space (PVS). In addition, RSD promoted recruitment of GFP+ macrophages into the PVS and parenchyma of the prefrontal cortex, amygdala, and hippocampus of GFP+ BM-chimeric mice. Furthermore, mice deficient in chemokine receptors associated with monocyte trafficking [chemokine receptor-2 knockout (CCR2KO) or fractalkine receptor knockout (CX3CR1KO)] failed to recruit macrophages to the brain and did not develop anxiety-like behavior following RSD. Last, RSD-induced macrophage trafficking was prevented in BM-chimeric mice generated with CCR2KO or CX3CR1KO donor cells. These findings indicate that monocyte recruitment to the brain in response to social stress represents a novel cellular mechanism that contributes to the development of anxiety. PMID:23966702

A comparative study of three detection techniques for Leifsonia xyli subsp. xyli, the causal pathogen of sugarcane ratoon stunting disease

USDA-ARS?s Scientific Manuscript database

Ratoon stunting disease (RSD), which is caused by the bacterium Leifsonia xyli subsp. xyli (Lxx), is now recognized worldwide as the most economically devastating disease impacting sugarcane. RSD causes significant yield losses and variety degradation. Diagnosis of RSD is challenging because it does...

Isolation and characterization of resistant gene analogs from RSD resistant and susceptible sugarcane clones: A progress report

USDA-ARS?s Scientific Manuscript database

Ratoon stunting disease (RSD) can decrease sugarcane yield by 5 to 15% if not properly managed. Currently, the disease is primarily managed by two approaches: breeding for RSD resistance and through sanitation, i.e., cleaning equipment and a clean seed program. Understanding the molecular basis of...

40 CFR 266.106 - Standards to control metals emissions.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-specific doses (RSDs) are listed for the carcinogenic metals. The RSD for a metal is the acceptable ambient... RSD as described in paragraph (d)(3) of this section. (3) Carcinogenic metals. For the carcinogenic... person resides on site) to the risk-specific dose (RSD) for all carcinogenic metals emitted shall not...

40 CFR 266.106 - Standards to control metals emissions.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-specific doses (RSDs) are listed for the carcinogenic metals. The RSD for a metal is the acceptable ambient... RSD as described in paragraph (d)(3) of this section. (3) Carcinogenic metals. For the carcinogenic... person resides on site) to the risk-specific dose (RSD) for all carcinogenic metals emitted shall not...

40 CFR 266.106 - Standards to control metals emissions.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-specific doses (RSDs) are listed for the carcinogenic metals. The RSD for a metal is the acceptable ambient... RSD as described in paragraph (d)(3) of this section. (3) Carcinogenic metals. For the carcinogenic... person resides on site) to the risk-specific dose (RSD) for all carcinogenic metals emitted shall not...

Regulation of Global Transcription in Escherichia coli by Rsd and 6S RNA

PubMed Central

Lal, Avantika; Krishna, Sandeep; Seshasayee, Aswin Sai Narain

2018-01-01

In Escherichia coli, the sigma factor σ70 directs RNA polymerase to transcribe growth-related genes, while σ38 directs transcription of stress response genes during stationary phase. Two molecules hypothesized to regulate RNA polymerase are the protein Rsd, which binds to σ70, and the non-coding 6S RNA which binds to the RNA polymerase-σ70 holoenzyme. Despite multiple studies, the functions of Rsd and 6S RNA remain controversial. Here we use RNA-Seq in five phases of growth to elucidate their function on a genome-wide scale. We show that Rsd and 6S RNA facilitate σ38 activity throughout bacterial growth, while 6S RNA also regulates widely different genes depending upon growth phase. We discover novel interactions between 6S RNA and Rsd and show widespread expression changes in a strain lacking both regulators. Finally, we present a mathematical model of transcription which highlights the crosstalk between Rsd and 6S RNA as a crucial factor in controlling sigma factor competition and global gene expression. PMID:29686109

Regulation of Global Transcription in Escherichia coli by Rsd and 6S RNA.

PubMed

Lal, Avantika; Krishna, Sandeep; Seshasayee, Aswin Sai Narain

2018-05-31

In Escherichia coli , the sigma factor σ 70 directs RNA polymerase to transcribe growth-related genes, while σ 38 directs transcription of stress response genes during stationary phase. Two molecules hypothesized to regulate RNA polymerase are the protein Rsd, which binds to σ 70 , and the non-coding 6S RNA which binds to the RNA polymerase-σ 70 holoenzyme. Despite multiple studies, the functions of Rsd and 6S RNA remain controversial. Here we use RNA-Seq in five phases of growth to elucidate their function on a genome-wide scale. We show that Rsd and 6S RNA facilitate σ 38 activity throughout bacterial growth, while 6S RNA also regulates widely different genes depending upon growth phase. We discover novel interactions between 6S RNA and Rsd and show widespread expression changes in a strain lacking both regulators. Finally, we present a mathematical model of transcription which highlights the crosstalk between Rsd and 6S RNA as a crucial factor in controlling sigma factor competition and global gene expression. Copyright © 2018 Lal et al.

Determination of saponins and flavonoids in ivy leaf extracts using HPLC-DAD.

PubMed

Yu, Miao; Shin, Young June; Kim, Nanyoung; Yoo, Guijae; Park, SeonJu; Kim, Seung Hyun

2015-04-01

A new method for the determination of six compounds, chlorogenic acid, rutin, nicotiflorin, hederacoside C, hederasaponin B and α-hederin, in ivy leaf extracts using high-performance liquid chromatography with diode array detector was developed. The chromatographic separation was performed on a YMC Hydrosphere C18 analytical column using a gradient elution of 0.1% phosphoric acid and acetonitrile. The method was validated in terms of specificity, linearity (r(2) > 0.9999), precision [relative standard deviation (RSD) < 0.36%] and accuracy (97.4-103.8%). The limit of detection and limit of quantification were <20.32 and 61.56 ng for all analytes, respectively. The tested compounds were found to be stable in the ivy leaf extract from 0 to 48 h, and the RSD value for each compound was <0.90%. The validated method was successfully applied to quantify all six compounds in a 30% ethanol ivy leaf extract and 13 ivy leaf extract products. The results showed that all the tested products satisfied the minimum requirement for the content of hederacoside C. However, there were some differences between the contents of other constituents. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Development and Application of an HPLC–UV Procedure to Determine Multiple Flavonoids and Phenolics in Acanthopanax Leaf Extracts

PubMed Central

Zhang, Xiaodan; Zhou, Xinqi; Liu, Xiangqian; Li, Xiaolong; Whang, Wankyunn

2016-01-01

Acanthopanax species are used in traditional medicine to treat numerous diseases. A simultaneous high-performance liquid chromatography (HPLC) method was developed and validated for the determination of the flavonoid and phenolic content of Acanthopanax leaves. HPLC analysis was performed on an AKZO NOBEL Kromasil 100-5C18 column (250 × 4.6 mm, 5 µm) using a gradient elution of acetonitrile–water containing 0.2% formic acid with a flow rate of 1.0 mL/min, monitored at 320 nm. The method was linear over the range 1–500 µg/mL (determination coefficients R2 > 0.999). Satisfactory intraday and interday precision was achieved, with the relative standard deviation (RSD) <2.99%. The mean recoveries measured at the three concentrations were in the range of 90.11–104.83%, with RSD <2.91% for the targets. Twenty-four samples of Acanthopanax leaves from different species and locations were examined using this analytical method, and their chemical profiles provided information for the chemotaxonomic investigation. The established method is simple, rapid and reliable for the quality control of Acanthopanax leaves of various species from different collections. The complete phenolic and flavonoid profiles of Acanthopanax leaves of various species have been established. PMID:26711585

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.

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.

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 %.

Development of magnetic micro-solid phase extraction for analysis of phthalate esters in packaged food.

PubMed

Makkliang, Fonthip; Kanatharana, Proespichaya; Thavarungkul, Panote; Thammakhet, Chongdee

2015-01-01

A novel, simple and low cost magnetic multi-walled carbon nanotubes-poly (vinyl alcohol) cryogel-micro-solid phase extraction (magnetic-MWCNTs-PVA cryogel-μ-SPE) sorbent was synthesized by incorporating magnetic particles and MWCNTs into a PVA cryogel. The magnetic-MWCNTs-PVA cryogel-μ-SPE sorbent developed, with a large surface area and macro-porous structure, provided good sorbent-to-sorbent reproducibility (%RSD<8) and each sorbent could be used up to 30 times (%RSD<6). This sorbent was applied for the extraction of dibutyl phthalate (DBP) and di-2-(ethylhexyl) phthalate (DEHP) in packaged food prior to analysis by gas chromatograph coupled with flame ionisation detector (GC-FID). The concentration of DBP and DEHP in hot-water samples from plastic bags were found in the range 0.04-0.15 μg mL(-1) and 0.03-0.20 μg mL(-1), respectively, but only DEHP was found in clear chicken soup samples in the range 0.02-0.07 μg mL(-1). Copyright © 2014 Elsevier Ltd. All rights reserved.

Glyoxal and methylglyoxal in Atlantic seawater and marine aerosol particles: method development and first application during the Polarstern cruise ANT XXVII/4

NASA Astrophysics Data System (ADS)

van Pinxteren, M.; Herrmann, H.

2013-06-01

An analytical method for the determination of the alpha dicarbonyls glyoxal (GLY) and methylglyoxal (MGLY) from seawater and marine aerosol samples is presented. The method is based on derivatisation with o-(2,3,4,5,6-Pentafluorobenzyl)-hydroxylamine (PFBHA) reagent, solvent extraction and GC-MS (SIM) analysis. The method showed good precision (RSD <10%), sensitivity (detection limits in the low ng L-1 range), and accuracy (good agreement between external calibration and standard addition). The method was applied to determine GLY and MGLY in oceanic water sampled during the POLARSTERN cruise ANT XXVII/4 from Capetown to Bremerhaven in spring 2011. GLY and MGLY were determined in the sea surface microlayer (SML) of the ocean and corresponding bulkwater (BW) with average concentrations of 228 ng L-1 (GLY) and 196 ng L-1 (MGLY). The results show a significant enrichment (factor of 4) of GLY and MGLY in the SML. Furthermore, marine aerosol particles (PM1) were sampled during the cruise and analyzed for GLY (average concentration 0.19 ng m-3) and MGLY (average concentration 0.15 ng m-3). On aerosol particles, both carbonyls show a very good correlation with oxalate, supporting the idea of a secondary formation of oxalic acid via GLY and MGLY. Concentrations of GLY and MGLY in seawater and on aerosol particles were correlated to environmental parameters such as global radiation, temperature, distance to the coastline and biological activity. There are slight hints for a photochemical production of GLY and MGLY in the SML (significant enrichment in the SML, higher enrichment at higher temperature). However, a clear connection of GLY and MGLY to global radiation as well as to biological activity cannot be concluded from the data. A slight correlation between GLY and MGLY in the SML and in aerosols could be a hint for interactions of especially GLY between seawater and the atmosphere.

Glyoxal and methylglyoxal in Atlantic seawater and marine aerosol particles: method development and first application during the Polarstern cruise ANT XXVII/4

NASA Astrophysics Data System (ADS)

van Pinxteren, M.; Herrmann, H.

2013-12-01

An analytical method for the determination of the alpha dicarbonyls glyoxal (GLY) and methylglyoxal (MGLY) from seawater and marine aerosol particles is presented. The method is based on derivatization with o-(2,3,4,5,6-Pentafluorobenzyl)-hydroxylamine (PFBHA) reagent, solvent extraction and GC-MS (SIM) analysis. The method showed good precision (RSD < 10%), sensitivity (detection limits in the low ng L-1 range), and accuracy (good agreement between external calibration and standard addition). The method was applied to determine GLY and MGLY in oceanic water sampled during the Polarstern cruise ANT XXVII/4 from Capetown to Bremerhaven in spring 2011. GLY and MGLY were determined in the sea surface microlayer (SML) of the ocean and corresponding bulk water (BW) with average concentrations of 228 ng L-1 (GLY) and 196 ng L-1 (MGLY). The results show a significant enrichment (factor of 4) of GLY and MGLY in the SML. Furthermore, marine aerosol particles (PM1) were sampled during the cruise and analyzed for GLY (average concentration 0.19 ng m-3) and MGLY (average concentration 0.15 ng m-3). On aerosol particles, both carbonyls show a very good correlation with oxalate, supporting the idea of a secondary formation of oxalic acid via GLY and MGLY. Concentrations of GLY and MGLY in seawater and on aerosol particles were correlated to environmental parameters such as global radiation, temperature, distance to the coastline and biological activity. There are slight hints for a photochemical production of GLY and MGLY in the SML (significant enrichment in the SML, higher enrichment at higher temperature). However, a clear connection of GLY and MGLY to global radiation as well as to biological activity cannot be concluded from the data. A slight correlation between GLY and MGLY in the SML and in aerosol particles could be a hint for interactions, in particular of GLY, between seawater and the atmosphere.

Shared and Unique Risk Factors Underlying Mathematical Disability and Reading and Spelling Disability.

PubMed

Slot, Esther M; van Viersen, Sietske; de Bree, Elise H; Kroesbergen, Evelyn H

2016-01-01

High comorbidity rates have been reported between mathematical learning disabilities (MD) and reading and spelling disabilities (RSD). Research has identified skills related to math, such as number sense (NS) and visuospatial working memory (visuospatial WM), as well as to literacy, such as phonological awareness (PA), rapid automatized naming (RAN) and verbal short-term memory (Verbal STM). In order to explain the high comorbidity rates between MD and RSD, 7-11-year-old children were assessed on a range of cognitive abilities related to literacy (PA, RAN, Verbal STM) and mathematical ability (visuospatial WM, NS). The group of children consisted of typically developing (TD) children (n = 32), children with MD (n = 26), children with RSD (n = 29), and combined MD and RSD (n = 43). It was hypothesized that, in line with the multiple deficit view on learning disorders, at least one unique predictor for both MD and RSD and a possible shared cognitive risk factor would be found to account for the comorbidity between the symptom dimensions literacy and math. Secondly, our hypotheses were that (a) a probabilistic multi-factorial risk factor model would provide a better fit to the data than a deterministic single risk factor model and (b) that a shared risk factor model would provide a better fit than the specific multi-factorial model. All our hypotheses were confirmed. NS and visuospatial WM were identified as unique cognitive predictors for MD, whereas PA and RAN were both associated with RSD. Also, a shared risk factor model with PA as a cognitive predictor for both RSD and MD fitted the data best, indicating that MD and RSD might co-occur due to a shared underlying deficit in phonological processing. Possible explanations are discussed in the context of sample selection and composition. This study shows that different cognitive factors play a role in mathematics and literacy, and that a phonological processing deficit might play a role in the occurrence of MD and RSD.

A new perspective on the raindrop size distribution and its implications for retrievals of light rainfall

NASA Astrophysics Data System (ADS)

Gatlin, P. N.; Thurai, M.; Petersen, W. A.; Bringi, V. N.

2017-12-01

As GPM facilitates precipitation estimation at higher latitudes where light rainfall is more common it becomes more important that we can fully describe the raindrop size distribution (RSD) across the continuum of observed raindrop sizes. An adequate understanding and the capability to represent the RSD in light rain and drizzle extends from GPM radar algorithms into radiometer-based algorithms, where auto-conversion from cloud to rainwater contents and size distributions becomes important for light rain/drizzle estimation. This study provides insights into the effect of small raindrops on our ability to accurately map rainfall. The RSD has been widely defined using a gamma distribution—the assumption often being verified and approach being reinforced using measurements that imperfectly measure the small end of the RSD. However, we find that the gamma model as it is applied in its current form, to include commonly used disdrometer measurements to define it, is not capable of accurately describing the small raindrops we have observed during light rainfall. We demonstrate the difficulty encountered at light rain rates (e.g., 0.5 mm/hr or less) and for drops typically < 0.6 - 0.7 mm in diameter using a disdrometer with a pixel resolution of 50 microns operated alongside a 2DVD, with both instruments inside a small DFIR wind fence. Measurements were made in two locations with different climates—Greely, Colorado and Huntsville, Alabama. The resultant comparison reveals that the gamma RSD model overestimates the characteristic raindrop diameter (Dm), especially for light rainfall. A generalized gamma distribution provides a closer fit to the RSD observations across the continuum of raindrop sizes and highlights a drizzle mode of the RSD exists that would otherwise not be described with the commonly used gamma RSD model. Our analysis also suggests that RSD-based separation of stratiform and convective rainfall requires special consideration for light rainfall cases, especially those with small mass-weighted mean diameters (Dm < 0.6 mm).

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.

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.

Negative-ion atmospheric pressure ionisation of semi-volatile fluorinated compounds for ultra-high-performance liquid chromatography tandem mass spectrometry analysis.

PubMed

Ayala-Cabrera, Juan F; Javier Santos, F; Moyano, Encarnación

2018-05-24

In this work, the feasibility of negative-ion atmospheric pressure chemical ionisation (APCI) and atmospheric pressure photoionisation (APPI) for ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) determination of fluorotelomer alcohols (FTOHs), fluorinated octanesulfonamides (FOSAs) and fluorinated octanesulfonamido-ethanols (FOSEs) was evaluated. The study of the effect of mobile phase composition on the atmospheric pressure ionisation of these compounds indicated that methanol/water mixtures provided the best responses in APCI, while acetonitrile/water with a post-column addition of toluene as dopant was the most appropriated mixture in APPI. Under the optimal working conditions, most of the target compounds produced the ion [M-H] - as base peak, although in-source collision-induced dissociation fragment ions in APCI and APPI and superoxide adduct ions [M+O 2 ] -• in APPI were also present. These ions proved to be more useful as precursor ions for MS/MS determination than the adduct ions generated in electrospray. Although the UHPLC-APCI-MS/MS method allowed the determination of these semi-volatile compounds at low concentration levels, the analysis by UHPLC-APPI-MS/MS provided the lowest limits of detection and it was applied to the analysis of water samples in combination with solid-phase extraction. Quality parameters demonstrated the good performance of the proposed method, providing low method limits of detection (0.3-6 ng L -1 ), good precision (RSD % < 5%) and an accurate quantification (relative error % < 14%). Among the river water samples analysed by the developed method, 4:2 FTOH and N-EtFOSA were determined at 30 and 780 ng L -1 , respectively.

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.

A highly sensitive and selective sensor based on a graphene-coated carbon paste electrode modified with a computationally designed boron-embedded duplex molecularly imprinted hybrid membrane for the sensing of lamotrigine.

PubMed

Wang, Hongjuan; Qian, Duo; Xiao, Xilin; Gao, Shuqin; Cheng, Jianlin; He, Bo; Liao, Lifu; Deng, Jian

2017-08-15

An innovative electrochemical sensor, based on a carbon paste electrode (CPE) modified with graphene (GR) and a boron-embedded duplex molecularly imprinted hybrid membrane (B-DMIHM), was fabricated for the highly sensitive and selective determination of lamotrigine (LMT). Density functional theory (DFT) was employed to study the interactions between the template and monomers to screen appropriate functional monomers for rational design of the B-DMIHM. The distinct synergic effect of GR and B-DMIHM was evidenced by the positive shift of the reduction peak potential of LMT at B-DMIHM/GR modified CPE (B-DMIHM/GR/CPE) by about 300mV, and the 13-fold amplification of the peak current, compared to a bare carbon paste electrode (CPE). The electrochemical reduction mechanism of lamotrigine was investigated by different voltammetric techniques. It was illustrated that square wave voltammetry (SWV) was more sensitive than different pulse voltammetry (DPV) for the quantitative analysis of LMT. Thereafter, a highly sensitive electroanalytical method for LMT was established by SWV at B-DMIHM/GR/CPE with a good linear relationship from 5.0×10 -8 to 5.0×10 -5 and 5.0×10 -5 to 3.0×10 -4 molL -1 with a lower detection limit (1.52×10 -9 molL -1 ) based on the lower linear range(S/N=3). The practical application of the sensor was demonstrated by determining the concentration of LMT in pharmaceutical and biological samples with good precision (RSD 1.04-4.41%) and acceptable recoveries (92.40-107.0%). Copyright © 2017 Elsevier B.V. All rights reserved.

Trace determination of Hg together with As, Sb, Se by miniaturized optical emission spectrometry integrated with chemical vapor generation and capacitively coupled argon microwave miniplasma discharge

NASA Astrophysics Data System (ADS)

Matusiewicz, Henryk; Ślachciński, Mariusz

2017-07-01

A miniaturized optical emission spectrometer (OES) with capacitively coupled argon microwave microplasma (μCMP) as and excitation source and chemical vapor generation (CVG) for sample introduction was constructed for the determination of trace Hg, As, Sb and Se. The applied method enabled simultaneous determination of hydride-forming elements (As, Sb, Se) and volatile Hg. Mercury cold vapor and the hydride volatile species of As, Sb and Se were generated when standard or sample solutions were separated from the liquid phase for transport to the capacitively coupled microwave microplasma and detection of their atomic emission. A univariate approach and the simplex optimization procedure were used to achieve optimized conditions and derive analytical figures of merit. The experimental concentration detection limits (LODs) for simultaneous determination, calculated as the concentration giving a signal equal to three times of the standard deviation of the blank (LOD, 3σblank criterion, peak height) were 3.0, 1.4, 1.5 and 3.8 ng mL- 1 for Hg, As, Sb and Se, respectively. The method was validated by the analysis of three Certified Reference Materials (NIST 2711, NRCC DOLT-2, NIST 1643e) of different matrix composition and by the standard addition technique. The method offers relatively good precision (RSD ranged from 5% to 8%) for microsampling (200 μL) analysis. The measured of contents of elements in certified reference materials were in good agreement with the certified values (Hg 1.99-6.25 μg g- 1, As 16.6-105 μg g- 1, Sb 19.4-56.88 μg g- 1, Se 1.52-11.68 μg g- 1), according to the Student t-test, for a confidence level of 95%.

Direct Compositional Characterization of (U,Th)O2 Powders, Microspheres, and Pellets Using TXRF.

PubMed

Dhara, Sangita; Prabhat, Parimal; Misra, N L

2015-10-20

A total reflection X-ray fluorescence (TXRF) analysis method for direct compositional characterization of sintered and green (U,Th)O2 samples in different forms (e.g., pellets, powders, and microspheres) without sample dissolution has been developed for the first time. The methodology involves transfer of only a few nanograms of the sample on the TXRF sample support by gently rubbing the samples on supports or taking their tiny uniform slurry in collodion on the sample support, drying them to make thin film, and measuring the TXRF spectra of the specimens thus prepared. This approach minimizes the matrix effects. Uranium determinations from the TXRF spectra of such specimens were made with respect to thorium, considering it as an internal standard. Samples having uranium atom percent (at%) from 0 to 100 in (U,Th)O2 were analyzed for uranium in comparison to thorium. The results showed an average precision of 2.6% (RSD, 2σ, n = 8). The TXRF-determined results deviated from expected values within 5%. The TXRF results were compared with those of biamperometry with good agreement. The lattice parameters of the solid solutions were calculated using their XRD patterns. A good correlation between lattice parameters and TXRF-determined U at% and between TXRF-determined U at% and expected U at%, calculated on the basis of preparation of (U,Th)O2 solid solutions, was obtained. The developed method is capable of analyzing (U,Th)O2 samples directly with almost negligible sample preparation and is well suited for radioactive samples. The present study suggests that this method can be extended for the determination of U,Th and Pu in other nuclear fuel materials (e.g., nitrides, carbides, etc.) in the form of pellets, powders, and microspheres after suitable modifications in sample handling procedure.

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.

Development of a Molecularly Imprinted Polymer-Based Sensor for the Electrochemical Determination of Triacetone Triperoxide (TATP)

PubMed Central

Mamo, Samuel Kassahun; Gonzalez-Rodriguez, Jose

2014-01-01

The explosive triacetone triperoxide (TATP), which can be prepared from commercially readily available reagents following an easy synthetic procedure, is one of the most common components of improvised explosive devices (IEDs). Molecularly-imprinted polymer (MIP) electrochemical sensors have proved useful for the determination of different compounds in different matrices with the required sensitivity and selectivity. In this work, a highly sensitive and selective molecularly imprinted polymer with electrochemical capabilities for the determination of TATP has been developed. The molecular imprinting has been performed via electropolymerisation onto a glassy carbon electrode surface by cyclic voltammetry from a solution of pyrrole functional monomer, TATP template and LiClO4. Differential Pulse Voltammetry of TATP, with LiClO4 as supporting electrolyte, was performed in a potential range of −2.0 V to +1.0 V (vs. Ag/AgCl). Three-factor two-level factorial design was used to optimise the monomer concentration at 0.1 mol·L−1, template concentration at 100 mmol·L−1 and the number of cyclic voltammetry scan cycles to 10. The molecularly imprinted polymer-modified glassy carbon electrode demonstrated good performance at low concentrations for a linear range of 82–44,300 μg·L−1 and a correlation coefficient of r2 = 0.996. The limits of detection (LoD) and quantification (LoQ) achieved were 26.9 μg·L−1 and 81.6 μg·L−1, respectively. The sensor demonstrated very good repeatability with precision values (n = 6, expressed as %RSD) of 1.098% and 0.55% for 1108 and 2216 μg·L−1, respectively. It also proved selective for TATP in the presence of other explosive substances such as PETN, RDX, HMX, and TNT. PMID:25490589

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.

Discipline for Students with Disabilities in the Recovery School District (RSD) of New Orleans

ERIC Educational Resources Information Center

Jeffers, Elizabeth K.

2014-01-01

This article focuses on special education in New Orleans post Hurricane Katrina. After Hurricane Katrina, Louisiana's Recovery School District (RSD) took over 102 of the city's 128 schools with the stated goal of creating a "choice district" for parents. This "choice distric"' is made up of RSD direct-run schools, Orleans…

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.

Effects of renal sympathetic denervation on cardiac sympathetic activity and function in patients with therapy resistant hypertension.

PubMed

van Brussel, Peter M; Eeftinck Schattenkerk, Daan W; Dobrowolski, Linn C; de Winter, Robbert J; Reekers, Jim A; Verberne, Hein J; Vogt, Liffert; van den Born, Bert-Jan H

2016-01-01

Renal sympathetic denervation (RSD) is currently being investigated in multiple studies of sympathetically driven cardiovascular diseases such as heart failure and arrhythmias. Our aim was to assess systemic and cardiac sympatholytic effects of RSD by the measurement of cardiac sympathetic activity and cardiovascular parameters. A total of 21 consecutive patients with refractory hypertension (daytime ambulatory blood pressure (BP)≥150/100 mmHg despite the use of 3 or more antihypertensive drugs), no evidence for secondary hypertension and normal renovascular anatomy were included. RSD was performed with the Medtronic Symplicity renal denervation catheter with an average of 4.2 (range 3-6) ablations per renal artery. To assess cardiac sympathetic activity, 123I-mIBG cardiac scintigraphy was performed before and 6 weeks after. In addition, the effect of RSD on peripheral BP and cardiac hemodynamics were assessed non-invasively. 123I-mIBG uptake before and after RSD was 1.7±0.4% vs. 1.7±0.5% at 15 min. and 1.4±0.4% vs. 1.5±0.5% after 4 h. As a consequence, washout rate was similar before (33.7±11.7%) and after RSD (30.1±12.6%, p=0.27). In line with earlier RSD studies, a significant drop in systolic office BP (-12.2 mmHg, p=0.04) was detected, whereas the decrease in ambulatory BP was not significant. No changes were seen in heart rate, stroke volume or left ventricular contractility, both in supine position and after standing. In concert with previous reports, RSD leads to a significant drop in office BP. However, a reduction in sympathetic activity could not be demonstrated on a cardiac level. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Interinstrument comparison of remote-sensing devices and a new method for calculating on-road nitrogen oxides emissions and validation of vehicle-specific power.

PubMed

Rushton, Christopher E; Tate, James E; Shepherd, Simon P; Carslaw, David C

2018-02-01

Emissions of nitrogen oxides (NOx) by vehicles in real driving environments are only partially understood. This has been brought to the attention of the world with recent revelations of the cheating of the type of approval tests exposed in the dieselgate scandal. Remote-sensing devices offer investigators an opportunity to directly measure in situ real driving emissions of tens of thousands of vehicles. Remote-sensing NO 2 measurements are not as widely available as would be desirable. The aim of this study is to improve the ability of investigators to estimate the NO 2 emissions and to improve the confidence of the total NOx results calculated from standard remote-sensing device (RSD) measurements. The accuracy of the RSD speed and acceleration module was also validated using state-of-the-art onboard global positioning system (GPS) tracking. Two RSDs used in roadside vehicle emissions surveys were tested side by side under off-carriageway conditions away from transient pollution sources to ascertain the consistency of their measurements. The speed correlation was consistent across the range of measurements at 95% confidence and the acceleration correlation was consistent at 95% confidence intervals for all but the most extreme acceleration cases. VSP was consistent at 95% confidence across all measurements except for those at VSP ≥ 15 kW t -1 , which show a small underestimate. The controlled distribution gas nitric oxide measurements follow a normal distribution with 2σ equal to 18.9% of the mean, compared to 15% observed during factory calibration indicative of additional error introduced into the system. Systematic errors of +84 ppm were observed but within the tolerance of the control gas. Interinstrument correlation was performed, with the relationship between the FEAT and the RSD4600 being linear with a gradient of 0.93 and an R 2 of 0.85, indicating good correlation. A new method to calculate NOx emissions using fractional NO 2 combined with NO measurements made by the RSD4600 was constructed, validated, and shown to be more accurate than previous methods. Synchronized remote-sensing measurements of NO were taken using two different remote-sensing devices in an off-road study. It was found that the measurements taken by both instruments were well correlated. Fractional NO 2 measurements from a prior study, measurable on only one device, were used to create new NO x emission factors for the device that could not be measured by the second device. These estimates were validated against direct measurement of total NO x emission factors and shown to be an improvement on previous methodologies. Validation of vehicle-specific power was performed with good correlation observed.

[Determination of six alkaloids in six types of Coptidis Rhizoma pieces by RP-HPLC and spectrum-effect relationships with anti-diabetes pharmacodynamics data].

PubMed

Lai, Xian-Rong; Zhou, Bang-Hua; Du, Ming-Sheng; Zheng, Hai-Jie; Geng, Zhi-Peng; Li, Jia-Chuan; Meng, Xian-Li; Zhang, Yi; Zhang, Jing

2016-12-01

To establish a method for determining the contents of six alkaloids (jatrorrhizine hydrochloride, columbamine hydrochloride, epiberberine hydrochloride, coptisine hydrochloride, palmatine hydrochloride, berberine hydrochloride) in six types of Coptidis Rhizoma pieces (crude pieces, ginger juice stir-fried pieces, vinegar stir-fried pieces, wine steamed pieces, wine stir-fried pieces, evodiae juice stir-fried pieces) by RP-HPLC, and explore the relationship with the curative effect of traditional Chinese medicine (TCM) and pharmacodynamics results. The chromatographic column was Welch XtimateTM C₁₈ (4.6 mm×250 mm, 5 μm), with 0.1% triethylamine solution (adjust pH at 10 with ammonium bicarbonate and ammonia) as mobile phase A and acetonitrile as mobile phase B for gradient elution (0-15 min, 10%-25%B; 15-25 min, 25%-30%B; 25-40 min, 30%-45%B) at a rate of 1.0 mL•min⁻¹. The column temperature was set at 30 ℃, and the wavelength was set at 270 nm. The six alkaloids showed a good linear relationship within the range of 0.85-16.96 mg•L⁻¹ (r=0.999 7), 1.25-24.96 mg•L⁻¹ (r=0.999 9), 2.05-40.96 mg•L⁻¹ (r=0.999 9), 3.65-72.96 mg•L⁻¹ (r=0.999 9), 2.88-57.60 mg•L⁻¹ (r=0.999 8), and 13.25-264.96 mg•L⁻¹ (r=0.999 6) respectively. The average recoveries (n=9) of the six alkaloids were 102.4% (RSD 1.2%), 101.8% (RSD 1.3%), 100.3% (RSD 1.8%), 100.7%(RSD 1.8%), 101.2% (RSD 1.5%) and 97.90% (RSD 2.0%) respectively, and their average contents were 3.55, 4.49, 9.12, 19.17, 15.69, 62.56 mg•g⁻¹, respectively. This determination method was accurate and repeatable, which could be used for the content determination in six types of Coptidis Rhizoma pieces. Data analysis on contents determination and preliminary pharmacodynamics results was conducted by using principal component analysis (PCA) and hierarchical clustering analysis (HCA). The analysis results showed that three types of Coptidis Rhizoma pieces (wine steamed pieces, wine stir-fried pieces, and evodiae juice stir-fried pieces) had significant differences with crude pieces, and the wine steamed Coptidis Rhizoma pieces showed most difference with crude pieces especially, mainly related to triglyceride (TG) and fasting blood glucose levels (FBG) in serum. In addition, columbamine hydrochloride was most affected among the six alkaloids. Those three types of Coptidis Rhizoma pieces (wine steamed pieces, wine stir-fried pieces, and evodiae juice stir-fried pieces), had more advantages for "anti-diabetes" in TCM clinical application, especially in the treatment of diabetic hyperlipidemia. Copyright© by the Chinese Pharmaceutical Association.

An in-Situ Chemical Analyzer for the Determination of Trace Ammonia in Natural Waters

NASA Astrophysics Data System (ADS)

Amornthammarong, N.; Ortner, P. B.; Hendee, J. C.

2014-12-01

In recent decades chemists have devoted a considerable effort to automating classical wet chemistry. The instruments manufactured for analysis of a large number of samples can be categorized into two main groups—batch and continuous flow analyzers. Our technique, autonomous batch analyzer (ABA), takes advantages of previously described batch analysis and continuous flow analysis. With its simpler design, ABA is robust, flexible, inexpensive, and requires minimal maintenance. ABA achieves complete mixing of sample with reagents using a syringe and a simple mixing chamber. The system can autonomously produce a calibration curve by auto-diluting a single stock standard solution. In addition it incorporates a pre-filtering subsystem enabling measurements in turbid, sediment-laden waters. Over the typical range for ammonia in marine waters (0-10 µM), the response is linear (r2 = 0.9930) with a limit of detection (S/N ratio > 3) of 10 nM. The working range for marine waters is 0.05-10 µM. Repeatability is 0.3% (n = 10) at an ammonia level of 2 μM. 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, a tidal pond and the Indian River Lagoon, FL. Diurnal cycles and possibly a tidal influence were expressed in the concentration variability observed.

Simultaneous HPLC-F analysis of three recent antiepileptic drugs in human plasma.

PubMed

Mercolini, Laura; Mandrioli, Roberto; Amore, Mario; Raggi, Maria Augusta

2010-09-21

An original high-performance liquid chromatographic method with fluorescence detection is presented for the simultaneous determination of the three antiepileptic drugs gabapentin, vigabatrin and topiramate in human plasma. After pre-column derivatisation with dansyl chloride, the analytes were separated on a Hydro-RP column with a mobile phase composed of phosphate buffer (55%) and acetonitrile (45%) and detected at lambda(em)=500 nm, exciting at 300 nm. An original pre-treatment procedure on biological samples, based on solid-phase extraction with MCX cartridges for gabapentin and vigabatrin, and with Plexa cartridges for topiramate, gave high extraction yields (>91%), satisfactory precision (RSD<6.4%) and good selectivity. Linearity was found in the 0.2-50.0 microg mL(-1) range for gabapentin, in the 1.0-100.0 microg mL(-1) range for vigabatrin and in the 1.0-50.0 microg mL(-1) range for topiramate, with limits of detection (LODs) between 0.1 and 0.3 microg mL(-1). After validation, the method was successfully applied to some plasma samples from patients undergoing therapy with one or more of these drugs. Accuracy results were satisfactory (recovery >91%). Therefore, the method seems to be suitable for the therapeutic drug monitoring (TDM) of patients treated with gabapentin, vigabatrin and topiramate. Copyright 2010 Elsevier B.V. All rights reserved.

A sustainable on-line CapLC method for quantifying antifouling agents like irgarol-1051 and diuron in water samples: Estimation of the carbon footprint.

PubMed

Pla-Tolós, J; Serra-Mora, P; Hakobyan, L; Molins-Legua, C; Moliner-Martinez, Y; Campins-Falcó, P

2016-11-01

In this work, in-tube solid phase microextraction (in-tube SPME) coupled to capillary LC (CapLC) with diode array detection has been reported, for on-line extraction and enrichment of booster biocides (irgarol-1051 and diuron) included in Water Frame Directive 2013/39/UE (WFD). The analytical performance has been successfully demonstrated. Furthermore, in the present work, the environmental friendliness of the procedure has been quantified by means of the implementation of the carbon footprint calculation of the analytical procedure and the comparison with other methodologies previously reported. Under the optimum conditions, the method presents good linearity over the range assayed, 0.05-10μg/L for irgarol-1051 and 0.7-10μg/L for diuron. The LODs were 0.015μg/L and 0.2μg/L for irgarol-1051 and diuron, respectively. Precision was also satisfactory (relative standard deviation, RSD<3.5%). The proposed methodology was applied to monitor water samples, taking into account the EQS standards for these compounds. The carbon footprint values for the proposed procedure consolidate the operational efficiency (analytical and environmental performance) of in-tube SPME-CapLC-DAD, in general, and in particular for determining irgarol-1051 and diuron in water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

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.

Pencil graphite electrodes for improved electrochemical detection of oleuropein by the combination of Natural Deep Eutectic Solvents and graphene oxide.

PubMed

Gomez, Federico J V; Spisso, Adrian; Fernanda Silva, María

2017-11-01

A novel methodology is presented for the enhanced electrochemical detection of oleuropein in complex plant matrices by Graphene Oxide Pencil Grahite Electrode (GOPGE) in combination with a buffer modified with a Natural Deep Eutectic Solvent, containing 10% (v/v) of Lactic acid, Glucose and H 2 O (LGH). The electrochemical behavior of oleuropein in the modified-working buffer was examined using differential pulse voltammetry. The combination of both modifications, NADES modified buffer and nanomaterial modified electrode, LGH-GOPGE, resulted on a signal enhancement of 5.3 times higher than the bare electrode with unmodified buffer. A calibration curve of oleuropein was performed between 0.10 to 37 μM and a good linearity was obtained with a correlation coefficient of 0.989. Detection and quantification limits of the method were obtained as 30 and 102 nM, respectively. In addition, precision studies indicated that the voltammetric method was sufficiently repeatable, %RSD 0.01 and 3.16 (n = 5) for potential and intensity, respectively. Finally, the proposed electrochemical sensor was successfully applied to the determination of oleuropein in an olive leaf extract prepared by ultrasound-assisted extraction. The results obtained with the proposed electrochemical sensor were compared with Capillary Zone Electrophoresis analysis with satisfactory results. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An isotope dilution capillary electrophoresis/tandem mass spectrometry (CE-MS/MS) method for the simultaneous measurement of choline, betaine, and dimethylglycine concentrations in human plasma.

PubMed

Forteschi, Mauro; Zinellu, Angelo; Assaretti, Stefano; Mangoni, Arduino A; Pintus, Gianfranco; Carru, Ciriaco; Sotgia, Salvatore

2016-10-01

Plasma concentrations of choline, betaine, and dimethylglycine provide valuable information on the flow of methyl groups in key biological processes, particularly during folate deficiency states. We developed a new method to simultaneously measure these analytes in human plasma. Following sample deproteinization using acetonitrile, an aliquot was evaporated to dryness under vacuum to be then taken up by water. Finally, analytes were separated by capillary electrophoresis and detected by electrospray ionization triple-quadrupole mass spectrometry, in multiple reaction monitoring mode, using two stable isotope-labeled internal standards. Linearity of the calibration curves of each analyte was good (R(2) > 0.99). Average limits of detection (LODs) and limits of quantification (LOQs) for choline, betaine, and dimethylglycine were, respectively, 0.43, 0.62, and 0.31 μmol/L and 1.52, 2.11, and 0.97 μmol/L. Mean recovery of three replicates of two spiked concentrations levels was close to 100 % for all of the analytes. Repeatability and intermediate precision, expressed as %RSD of measurements, were <9 %. The method, applied to measure analytes in samples from 30 patients with chronic kidney disease and 30 age- and sex-matched healthy controls, was able to detect differences between groups and the sexes.

Preparation and application of in-fibre internal standardization solid-phase microextraction.

PubMed

Zhao, Wennan; Ouyang, Gangfeng; Pawliszyn, Janusz

2007-03-01

The in-fibre standardization method is a novel approach that has been developed for field sampling/sample preparation, in which an internal standard is pre-loaded onto a solid-phase microextraction (SPME) fibre for calibration of the extraction of target analytes in field samples. The same method can also be used for in-vial sample analysis. In this study, different techniques to load the standard to a non-porous SPME fibre were investigated. It was found that the appropriateness of the technique depends on the physical properties of the standards that are used for the analysis. Headspace extraction of the standard dissolved in pumping oil works well for volatile compounds. Conversely, headspace extraction of the pure standard is an effective approach for semi-volatile compounds. For compounds with low volatility, a syringe-fibre transfer method and direct extraction of the standard dissolved in a solvent exhibited a good reproducibility (<5% RSD). The main advantage of the approaches investigated in this study is that the standard generation vials can be reused for hundreds of analyses without exhibiting significant loss. Moreover, most of the standard loading processes studied can be performed automatically, which is efficient and precise. Finally, the standard loading technique and in-fibre standardization method were applied to a complex matrix (milk) and the results illustrated that the matrix effect can be effectively compensated for with this approach.

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.

Synthesis and characterization of a material derived from 4-mercaptobenzoic acid: A novel platform for oligonucleotide immobilization.

PubMed

Alves, Rafael da Fonseca; da Silva, Amanda Gonçalves; Ferreira, Lucas Franco; Franco, Diego Leoni

2017-04-01

This paper reports the electrochemical modification of pencil carbon graphite electrodes with a polymeric material derived from 4-mercaptobenzoic acid. Acidic solutions (pH 0 and 5.02) yielded an insulating polymeric film with anionic permselective properties. Scanning Electron Microscopy (SEM) analysis showed a complete coverage of the carbon graphite electrodes with a laminar-like polymeric structure. Different characterization studies indicate that the carboxyl group remained unchanged since the absorbance peak and oxidation potential did not change with the increase in pH at the pK a accounting for the carboxyl/carboxylate redox transition. The functionalized matrix was activated using carbodiimide, succinimide and an amine-modified oligonucleotide. The immobilization and hybridization processes were successfully verified using the redox electroactive indicator methylene blue, where better electrochemical signals were obtained when compared with the traditional self-assembled monolayer system. The selectivity of the system was verified using a noncomplementary target where no significant difference in electric current was observed when compared to the system containing only the probe. The method showed a good linear correlation coefficient (r 2 =0.9915), low limit of detection (1.17nmolL -1 ), and an acceptable precision (RSD=2.75%). The proposed method is suitable for further studies using different sequences of oligonucleotides. Copyright © 2016 Elsevier B.V. All rights reserved.

Surfactant-based ionic liquids for extraction of phenolic compounds combined with rapid quantification using capillary electrophoresis.

PubMed

Huang, Fangzhi; Berton, Paula; Lu, Chengfei; Siraj, Noureen; Wang, Chun; Magut, Paul K S; Warner, Isiah M

2014-09-01

A rapid liquid phase extraction employing a novel hydrophobic surfactant-based room temperature ionic liquid (RTIL), tetrabutylphosphonium dioctyl sulfosuccinate ([4C4 P][AOT]), coupled with capillary electrophoretic-UV (CE-UV) detection is developed for removal and determination of phenolic compounds. The long-carbon-chain RTIL used is sparingly soluble in most solvents and can be used to replace volatile organic solvents. This fact, in combination with functional-surfactant-anions, is proposed to reduce the interfacial energy of the two immiscible liquid phases, resulting in highly efficient extraction of analytes. Several parameters that influence the extraction efficiencies, such as extraction time, RTIL type, pH value, and ionic strength of aqueous solutions, were investigated. It was found that, under acidic conditions, most of the investigated phenols were extracted from aqueous solution into the RTIL phase within 12 min. Good linearity was observed over the concentration range of 0.1-80.0 μg/mL for all phenols investigated. The precision of this method, expressed as RSD, was determined to be within 3.4-5.3% range. The LODs (S/N = 3) of the method were in the range of 0.047-0.257 μg/mL. The proposed methodology was successfully applied to determination of phenols in real water samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

A digital PCR method for identifying and quantifying adulteration of meat species in raw and processed food

PubMed Central

Ren, Junan; Deng, Tingting; Huang, Wensheng; Chen, Ying; Ge, Yiqiang

2017-01-01

Meat adulteration is a worldwide concern. In this paper, a new droplet digital PCR (ddPCR) method was developed for the quantitative determination of the presence of chicken in sheep and goat meat products. Meanwhile, a constant (multiplication factor) was introduced to transform the ratio of copy numbers to the proportion of meats. The presented ddPCR method was also proved to be more accurate (showing bias of less than 9% in the range from 5% to 80%) than real-time PCR, which has been widely used in this determination. The method exhibited good repeatability and stability in different thermal treatments and at ultra-high pressure. The relative standard deviation (RSD) values of 5% chicken content was less than 5.4% for ultra-high pressure or heat treatment. Moreover, we confirmed that different parts of meat had no effect on quantification accuracy of the ddPCR method. In contrast to real-time PCR, we examined the performance of ddPCR as a more precise, sensitive and stable analytical strategy to overcome potential problems of discrepancies in amplification efficiency discrepancy and to obtain the copy numbers directly without standard curves. The method and strategy developed in this study can be applied to quantify the presence and to confirm the absence of adulterants not only to sheep but also to other kinds of meat and meat products. PMID:28319152

Assessment of pesticide contamination in soil samples from an intensive horticulture area, using ultrasonic extraction and gas chromatography-mass spectrometry.

PubMed

Gonçalves, C; Alpendurada, M F

2005-03-15

In order to reduce the amount of sample to be collected and the time consumed in the analytical process, a broad range of analytes should be preferably considered in the same analytical procedure. A suitable methodology for pesticide residue analysis in soil samples was developed based on ultrasonic extraction (USE) and gas chromatography-mass spectrometry (GC-MS). For this study, different classes of pesticides were selected, both recent and old persistent molecules: parent compounds and degradation products, namely organochlorine, organophosphorous and pyrethroid insecticides, triazine and acetanilide herbicides and other miscellaneous pesticides. Pesticide residues could be detected in the low- to sub-ppb range (0.05-7.0mugkg(-1)) with good precision (7.5-20.5%, average 13.7% R.S.D.) and extraction efficiency (69-118%, average 88%) for the great majority of analytes. This methodology has been applied in a monitoring program of soil samples from an intensive horticulture area in Póvoa de Varzim, North of Portugal. The pesticides detected in four sampling programs (2001/2002) were the following: lindane, dieldrin, endosulfan, endosulfan sulfate, 4,4'-DDE, 4,4'-DDD, atrazine, desethylatrazine, alachlor, dimethoate, chlorpyrifos, pendimethalin, procymidone and chlorfenvinphos. Pesticide contamination was investigated at three depths and in different soil and crop types to assess the influence of soil characteristics and trends over time.

Partitioning of organophosphorus pesticides into phosphatidylcholine small unilamellar vesicles studied by second-derivative spectrophotometry

NASA Astrophysics Data System (ADS)

Takegami, Shigehiko; Kitamura, Keisuke; Ohsugi, Mayuko; Ito, Aya; Kitade, Tatsuya

2015-06-01

In order to quantitatively examine the lipophilicity of the widely used organophosphorus pesticides (OPs) chlorfenvinphos (CFVP), chlorpyrifos-methyl (CPFM), diazinon (DZN), fenitrothion (FNT), fenthion (FT), isofenphos (IFP), profenofos (PFF) and pyraclofos (PCF), their partition coefficient (Kp) values between phosphatidylcholine (PC) small unilamellar vesicles (SUVs) and water (liposome-water system) were determined by second-derivative spectrophotometry. The second-derivative spectra of these OPs in the presence of PC SUV showed a bathochromic shift according to the increase in PC concentration and distinct derivative isosbestic points, demonstrating the complete elimination of the residual background signal effects that were observed in the absorption spectra. The Kp values were calculated from the second-derivative intensity change induced by addition of PC SUV and obtained with a good precision of R.S.D. below 10%. The Kp values were in the order of CPFM > FT > PFF > PCF > IFP > CFVP > FNT ⩾ DZN and did not show a linear correlation relationship with the reported partition coefficients obtained using an n-octanol-water system (R2 = 0.530). Also, the results quantitatively clarified the effect of chemical-group substitution in OPs on their lipophilicity. Since the partition coefficient for the liposome-water system is more effective for modeling the quantitative structure-activity relationship than that for the n-octanol-water system, the obtained results are toxicologically important for estimating the accumulation of these OPs in human cell membranes.

HPLC/ELSD analysis of amidated bile acids: an effective and rapid way to assist continuous flow chemistry processes.

PubMed

Sardella, Roccaldo; Gioiello, Antimo; Ianni, Federica; Venturoni, Francesco; Natalini, Benedetto

2012-10-15

The employment of the flow N-acyl amidation of natural bile acids (BAs) required the in-line connection with suitable analytical tools enabling the determination of reaction yields as well as of the purity grade of the synthesized glyco- and tauro-conjugated derivatives. In this framework, a unique HPLC method was successfully established and validated for ursodeoxycholic (UDCA), chenodeoxycholic (CDCA), deoxycholic (DCA) and cholic (CA) acids, as well as the corresponding glyco- and tauro-conjugated forms. Because of the shared absence of relevant chromophoric moieties in the sample structure, an evaporative light scattering detector (ELSD) was profitably utilized for the analysis of such steroidal species. For each of the investigated compounds, all the runs were contemporarily carried out on the acidic free and the two relative conjugated variants. The different ELSD response of the free and the corresponding conjugated BAs, imposed to build-up separate calibration curves. In all the cases, very good precision (RSD% values ranging from 1.04 to 6.40% in the long-period) and accuracy (Recovery% values ranging from 96.03 to 111.14% in the long-period) values along with appreciably low LOD and LOQ values (the former being within the range 1-27 ng mL(-1) and the latter within the range 2-44 ng mL(-1)) turned out. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of a laser ablation-hollow cathode glow discharge emission source and the application to the analysis of steel samples.

PubMed

Naeem, Tariq M; Matsuta, Hideyuki; Wagatsuma, Kazuaki

2004-12-01

A novel atomic emission spectrometry comprising laser ablation as a sampling source and hollow cathode plasma for the excitation of ablated sample atoms is proposed. In this arrangement, a conventional Grimm-type discharge lamp is employed, but the polarity of the power supply is reversed so that the cylindrical hollow tube acts as a cathode and the glow discharge plasma is produced within this tube. A laser is irradiated to introduce sample atoms into the discharge plasma. Ablated atoms are excited by collisions with electrons and gas species, and emit characteristic radiation upon de-excitation. The experiments were conducted only in an atmosphere of helium gas so as to avoid a rapid erosion of the cathode hollow tube. Phase-sensitive detection with a lock-in amplifier was utilized to reject the continuous background emission of the plasma gas and emissions of sputtered atoms from the tube material. The unique feature of this technique is that the sampling and excitation processes can be controlled independently. The proposed technique was employed for the determination of Cr, Mn, and Ni in low-alloyed steel samples. The obtained concentrations are in good agreement with the reported values. The relative standard deviation (RSD), a measure of the analytical precision, was estimated to be 2-9% for Cr, 3-4% for Mn, and 4-11% for Ni determination.

[Correlations between Beck's suicidal ideation scale, suicidal risk assessment scale RSD and Hamilton's depression rating scale].

PubMed

Ducher, J-L; Dalery, J

2008-04-01

Most of the people who will attempt suicide, talk about it beforehand. Therefore, recognition of suicidal risk is not absolutely impossible. Beck's suicidal ideation scale and Ducher's suicidal risk assessment scale (RSD) are common tools to help practicians in this way. These scales and the Hamilton's depression scale were included in an international multicentric, phase IV, double-blind study, according to two parallel groups who had been administered a fixed dose of fluvoxamin or fluoxetin for six weeks. This allowed examination of the correlations between these scales and the relations, which could possibly exist between suicidal risk, depression and anxiety. (a) Relationships between the Beck's suicidal ideation scale, the suicidal risk assessment scale RSD and Hamilton's depression before treatment. Before treatment, the analysis was conducted with 108 male and female depressive outpatients, aged 18 or over. Results revealed a significant positive correlation (with a Pearson's correlation coefficient r equal to 0.69 and risk p<0.0001) between Beck's suicidal ideation scale and the suicidal risk assessment scale RSD. These scales correlate less consistently with Hamilton's depression (Beck/Hamilton's depression: r=0.34; p=0.0004-RSD/Hamilton's depression: r=0.35; p=0.0002). We observed that the clinical anxiety scale by Snaith is also strongly correlated to these two suicidal risk assessment scales (Beck/CAS: r=0.48; p<0.0001-RSD/CAS: r=0.35; p=0.0005). Besides, the item "suicide" of Hamilton's depression scale accounts for more than a third of the variability of Beck's suicidal ideation scale and the suicidal risk assessment scale RSD. According to these results, the suicidal risk evaluated by these two scales seems to be significantly correlated with anxiety as much as with depression. On the other hand, the Clinical Global Impression is fairly significantly correlated with Beck's suicidal ideation scale (r=0.22; p=0.02), unlike the suicidal risk assessment scale RSD (r=0.42; p<0.0001) and Hamilton's depression scale (r=0.58; p<0.0001); (b) Relationships between Beck's suicidal ideation scale, the suicidal risk assessment scale RSD and Hamilton's depression under treatment. The follow-up under treatment (fluvoxamin or fluoxetin) during six weeks revealed the significantly better sensitivity of the RSD in comparison with Beck's suicidal ideation scale and Hamilton's depression scale, showing the significantly faster improvement in the RSD (p<0.0001). There was no significant difference between the evolution of Beck's suicidal ideation scale and Hamilton's depression scale. So, under treatment with fluvoxamin or fluoxetin, the improvement in suicidal risk appears to be as rapid as the improvement in depression. If we look at the treatment prescribed, only the suicidal risk assessment scale RSD revealed a significant difference between the two molecules, with more rapid improvement with fluvoxamin (p=0.015) from D14. In conclusion, the results of this study hypothesize that the suicidal risk, as assessed by Beck's suicidal ideation scale and the suicidal risk assessment scale RSD, appears to be consistently correlated with both the level of anxiety and depression. The study also suggests that all antidepressants may not be equally effective on suicidal risk.

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.

Determination of perfluorinated compounds in fish fillet homogenates: method validation and application to fillet homogenates from the Mississippi River.

PubMed

Malinsky, Michelle Duval; Jacoby, Cliffton B; Reagen, William K

2011-01-10

We report herein a simple protein precipitation extraction-liquid chromatography tandem mass spectrometry (LC/MS/MS) method, validation, and application for the analysis of perfluorinated carboxylic acids (C7-C12), perfluorinated sulfonic acids (C4, C6, and C8), and perfluorooctane sulfonamide (FOSA) in fish fillet tissue. The method combines a rapid homogenization and protein precipitation tissue extraction procedure using stable-isotope internal standard (IS) calibration. Method validation in bluegill (Lepomis macrochirus) fillet tissue evaluated the following: (1) method accuracy and precision in both extracted matrix-matched calibration and solvent (unextracted) calibration, (2) quantitation of mixed branched and linear isomers of perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) with linear isomer calibration, (3) quantitation of low level (ppb) perfluorinated compounds (PFCs) in the presence of high level (ppm) PFOS, and (4) specificity from matrix interferences. Both calibration techniques produced method accuracy of at least 100±13% with a precision (%RSD) ≤18% for all target analytes. Method accuracy and precision results for fillet samples from nine different fish species taken from the Mississippi River in 2008 and 2009 are also presented. Copyright © 2010 Elsevier B.V. All rights reserved.

Test and evaluation of the Argonne BPAC10 Series air chamber calorimeter designed for 20 minute measurements

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

Perry, R.B.; Fiarman, S.; Jung, E.A.

1990-10-01

This paper is the final report on DOE-OSS Task ANLE88002 Fast Air Chamber Calorimetry.'' The task objective was to design, construct, and test an isothermal air chamber calorimeter for plutonium assay of bulk samples that would meet the following requirements for sample power measurement: average sample measurement time less than 20 minutes. Measurement of samples with power output up to 10 W. Precision of better than 1% RSD for sample power greater than 1 W. Precision better than 0.010 watt SD, for sample power less than 1 W. This report gives a description of the calorimeter hardware and software andmore » discusses the test results. The instrument operating procedure, included as an appendix, gives examples of typical input/output and explains the menu driven software. Sample measurement time of less than 20 minutes was attained by pre-equilibration of the samples in low cost precision preheaters and by prediction of equilibrium measurements. Tests at the TA55 Plutonium Facility at Los Alamos National Laboratory, on typical samples, indicates that the instrument meets all the measurement requirements.« less

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.

Determination of the neuropharmacological drug nodakenin in rat plasma and brain tissues by liquid chromatography tandem mass spectrometry: Application to pharmacokinetic studies.

PubMed

Song, Yingshi; Yan, Huiyu; Xu, Jingbo; Ma, Hongxi

2017-09-01

A rapid and sensitive liquid chromatography tandem mass spectrometry detection using selected reaction monitoring in positive ionization mode was developed and validated for the quantification of nodakenin in rat plasma and brain. Pareruptorin A was used as internal standard. A single step liquid-liquid extraction was used for plasma and brain sample preparation. The method was validated with respect to selectivity, precision, accuracy, linearity, limit of quantification, recovery, matrix effect and stability. Lower limit of quantification of nodakenin was 2.0 ng/mL in plasma and brain tissue homogenates. Linear calibration curves were obtained over concentration ranges of 2.0-1000 ng/mL in plasma and brain tissue homogenates for nodakenin. Intra-day and inter-day precisions (relative standard deviation, RSD) were <15% in both biological media. This assay was successfully applied to plasma and brain pharmacokinetic studies of nodakenin in rats after intravenous administration. Copyright © 2017 John Wiley & Sons, Ltd.

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.

Verification of spectrophotometric method for nitrate analysis in water samples

NASA Astrophysics Data System (ADS)

Kurniawati, Puji; Gusrianti, Reny; Dwisiwi, Bledug Bernanti; Purbaningtias, Tri Esti; Wiyantoko, Bayu

2017-12-01

The aim of this research was to verify the spectrophotometric method to analyze nitrate in water samples using APHA 2012 Section 4500 NO3-B method. The verification parameters used were: linearity, method detection limit, level of quantitation, level of linearity, accuracy and precision. Linearity was obtained by using 0 to 50 mg/L nitrate standard solution and the correlation coefficient of standard calibration linear regression equation was 0.9981. The method detection limit (MDL) was defined as 0,1294 mg/L and limit of quantitation (LOQ) was 0,4117 mg/L. The result of a level of linearity (LOL) was 50 mg/L and nitrate concentration 10 to 50 mg/L was linear with a level of confidence was 99%. The accuracy was determined through recovery value was 109.1907%. The precision value was observed using % relative standard deviation (%RSD) from repeatability and its result was 1.0886%. The tested performance criteria showed that the methodology was verified under the laboratory conditions.

An efficient repeating signal detector to investigate earthquake swarms

NASA Astrophysics Data System (ADS)

Skoumal, Robert J.; Brudzinski, Michael R.; Currie, Brian S.

2016-08-01

Repetitive earthquake swarms have been recognized as key signatures in fluid injection induced seismicity, precursors to volcanic eruptions, and slow slip events preceding megathrust earthquakes. We investigate earthquake swarms by developing a Repeating Signal Detector (RSD), a computationally efficient algorithm utilizing agglomerative clustering to identify similar waveforms buried in years of seismic recordings using a single seismometer. Instead of relying on existing earthquake catalogs of larger earthquakes, RSD identifies characteristic repetitive waveforms by rapidly identifying signals of interest above a low signal-to-noise ratio and then grouping based on spectral and time domain characteristics, resulting in dramatically shorter processing time than more exhaustive autocorrelation approaches. We investigate seismicity in four regions using RSD: (1) volcanic seismicity at Mammoth Mountain, California, (2) subduction-related seismicity in Oaxaca, Mexico, (3) induced seismicity in Central Alberta, Canada, and (4) induced seismicity in Harrison County, Ohio. In each case, RSD detects a similar or larger number of earthquakes than existing catalogs created using more time intensive methods. In Harrison County, RSD identifies 18 seismic sequences that correlate temporally and spatially to separate hydraulic fracturing operations, 15 of which were previously unreported. RSD utilizes a single seismometer for earthquake detection which enables seismicity to be quickly identified in poorly instrumented regions at the expense of relying on another method to locate the new detections. Due to the smaller computation overhead and success at distances up to ~50 km, RSD is well suited for real-time detection of low-magnitude earthquake swarms with permanent regional networks.

Impacts of rapeseed dregs on Cd availability in contaminated acid soil and Cd translocation and accumulation in rice plants.

PubMed

Yang, Wen-Tao; Gu, Jiao-Feng; Zou, Jia-Ling; Zhou, Hang; Zeng, Qing-Ru; Liao, Bo-Han

2016-10-01

The objective of the present study was to investigate the effects of rapeseed dregs (RSD, a commonly organic fertilizer in rural China) at application rates of 0, 0.75, 1.5, and 3.0 % on Cd availability in soil and its accumulation in rice plants (Oryza sativa L., Xiangwanxian 12 # , and Weiyou 46 # ) by means of a pot experiment. The results showed that application of RSD resulted in a sharp decrease in the soil TCLP-extractable Cd content. However, the soil TCLP-extractable Cd content in amended soil gradually increased during the rice growing period. Application of RSD significantly increased Cd transport from root to shoot and the amount of Cd accumulated in the aerial part. RSD was an effective organic additive for increasing rice grain yield, but total Cd content in rice grain was also increased. At an application rate of 1.5-3.0 % RSD, the total Cd content in Weiyou 46 # brown rice was 0.27-0.31 mg kg -1 , which exceeded the standard safe limit (0.2 mg kg -1 ) and was also higher than that of Xiangwanxian 12 # (0.04-0.14 mg kg -1 ). Therefore, Weiyou 46 # had a higher dietary risk than Xiangwanxian 12 # with RSD application. We do not recommend planting Weiyou 46 # and applying more than 0.75 % RSD in Cd-contaminated paddy fields.

Stereospecific analysis of sakuranetin by high-performance liquid chromatography: pharmacokinetic and botanical applications.

PubMed

Takemoto, Jody K; Remsberg, Connie M; Yáñez, Jaime A; Vega-Villa, Karina R; Davies, Neal M

2008-11-01

A stereospecific method for analysis of sakuranetin was developed. Separation was accomplished using a Chiralpak AD-RH column with UV (ultraviolet) detection at 288 nm. The stereospecific linear calibration curves ranged from 0.5 to 100 microg/mL. The mean extraction efficiency was >98%. Precision of the assay was <12% (relative standard deviation (R.S.D.)%), and within 10% at the limit of quantitation (0.5 microg/mL). Bias of the assay was lower than 10%, and within 5% at the limit of quantitation. The assay was applied successfully to pharmacokinetic quantification in rats, and the stereospecific quantification in oranges, grapefruit juice, and matico (Piper aduncum L.).

Liquid chromatographic determination of benzocaine and N-acetylbenzocaine in the edible fillet tissue from rainbow trout

USGS Publications Warehouse

Meinertz, J.R.; Stehly, G.R.; Hubert, T.D.; Bernardy, J.A.

1999-01-01

A method was developed for determining benzocaine and N-acetylbenzocaine concentrations in fillet tissue of rainbow trout. The method involves extracting the analytes with acetonitrile, removing lipids or hydrophobic compounds from the extract with hexane, and providing additional clean-up with solid-phase extraction techniques. Analyte concentrations are determined using reversed-phase high-performance liquid chromatographic techniques with an isocratic mobile phase and UV detection. The accuracy (range, 92 to 121%), precision (R.S.D., <14%), and sensitivity (method quantitation limit, <24 ng/g) for each analyte indicate the usefulness of this method for studies characterizing the depletion of benzocaine residues from fish exposed to benzocaine. Copyright (C) 1999.

Quantitative capillary electrophoresis and its application in analysis of alkaloids in tea, coffee, coca cola, and theophylline tablets.

PubMed

Li, Mengjia; Zhou, Junyi; Gu, Xue; Wang, Yan; Huang, Xiaojing; Yan, Chao

2009-01-01

A quantitative CE (qCE) system with high precision has been developed, in which a 4-port nano-valve was isolated from the electric field and served as sample injector. The accurate amount of sample was introduced into the CE system with high reproducibility. Based on this system, consecutive injections and separations were performed without voltage interruption. Reproducibilities in terms of RSD lower than 0.8% for retention time and 1.7% for peak area were achieved. The effectiveness of the system was demonstrated by the quantitative analysis of caffeine, theobromine, and theophylline in real samples, such as tea leaf, roasted coffee, coca cola, and theophylline tablets.

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.

Speciation analysis of inorganic antimony in soil using HPLC-ID-ICP-MS.

PubMed

Amereih, Sameer; Meisel, Thomas; Kahr, Elisabeth; Wegscheider, Wolfhard

2005-12-01

Speciation analysis of Sb(III) and Sb(V) in a soil sample was performed through extraction and on-line isotope dilution concentration determination after a chromatographic separation. The total Sb concentration found in a through traffic contaminated soil sample was (4.17 microg g(-1), 0.3 microg g(-1) SD, n=6). It was determined using ICP-MS after soil digestion using the sodium peroxide sintering method. The optimized extraction procedure for speciation analysis was carried out using 100 mmol L(-1) citric acid at pH 2.08 by applying an ultrasonic bath for 45 min at room temperature. The effects of citric acid concentration (0-500 mmol L(-1)), pH (1-6), and temperature (30-60 degrees C) on inorganic antimony species distribution in the examined sample were studied and optimized. The separation of Sb(III) and Sb(V) was achieved using an anion exchange column (PRP-X100) and 10 mmol L(-1) EDTA and 1 mmol L(-1) phthalic acid at pH 4.5 as a mobile phase. The eluent from the HPLC was mixed with an enriched (94.2%) (123)Sb spike solution that was pumped by a peristaltic pump with a constant flow rate (0.5 mL min(-1)) in a three-way valve. The blend passed directly to the Conikal nebulizer of the ICP-MS. By using the above extraction procedure and methodology, 43.2% Sb(V) (2.9% RSD, n=3) and 6.0% Sb(III) (1.3% RSD, n=3) of total Sb found in the sample could be detected. The detection limits achieved by the proposed method were 20 ng L(-1) and 65 ng L(-1) for Sb(V) and Sb(III), respectively. The precision, evaluated by using RSD with 100 ng L(-1) calibration solutions, was 2.7% and 3.2% (n=6) for Sb(V) and Sb(III), respectively, in aqueous solutions.

Renal sympathetic denervation alleviates myocardial fibrosis following isoproterenol-induced heart failure.

PubMed

Wang, Neng; Zheng, Xiaoxin; Qian, Jin; Yao, Wei; Bai, Lu; Hou, Guo; Qiu, Xuan; Li, Xiaoyan; Jiang, Xuejun

2017-10-01

The aim of the present study was to determine if renal sympathetic denervation (RSD) may alleviate isoproterenol-induced left ventricle remodeling, and to identify the underlying mechanism. A total of 70 rats were randomly divided into control (n=15), sham operation (n=15), heart failure (HF) with sham operation (HF + sham; n=20) and HF with treatment (HF + RSD; n=20) groups. The HF model was established by subcutaneous injection of isoproterenol; six weeks later, 1eft ventricular internal diameter at end‑systole (LVIDs), left ventricular systolic posterior wall thickness (LVPWs), 1eft ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were measured. Plasma norepinephrine (NE), angiotensin II (Ang II) and aldosterone (ALD) levels were measured by ELISA. Myocardial collagen volume fraction (CVF) was determined by Masson's staining. Reverse transcription‑quantitative polymerase chain reaction was used to determine the mRNA expression levels of ventricular transforming growth factor‑β (TGF‑β), connective tissue growth factor (CTGF) and microRNAs (miRs), including miR‑29b, miR‑30c and miR‑133a. The results demonstrated that LVIDs and LVPWs in the HF + RSD group were significantly decreased compared with the HF + sham group. By contrast, LVFS and LVEF in the HF + RSD group were significantly increased compared with the HF + sham group. RSD significantly reduced the levels of plasma NE, Ang II and ALD. CVF in the HF + RSD group was reduced by 38.1% compared with the HF + sham group. Expression levels of TGF‑β and CTGF were decreased, whereas those of miR‑29b, miR‑30c and miR‑133a were increased, in the HF + RSD group compared with the HF + sham group. These results indicated that RSD alleviates isoproterenol‑induced left ventricle remodeling potentially via downregulation of TGF‑β/CTGF and upregulation of miR‑29b, miR‑30c and miR‑133a. RSD may therefore be an effective non‑drug therapy for the treatment of heart failure.

Renal sympathetic denervation alleviates myocardial fibrosis following isoproterenol-induced heart failure

PubMed Central

Wang, Neng; Zheng, Xiaoxin; Qian, Jin; Yao, Wei; Bai, Lu; Hou, Guo; Qiu, Xuan; Li, Xiaoyan; Jiang, Xuejun

2017-01-01

The aim of the present study was to determine if renal sympathetic denervation (RSD) may alleviate isoproterenol-induced left ventricle remodeling, and to identify the underlying mechanism. A total of 70 rats were randomly divided into control (n=15), sham operation (n=15), heart failure (HF) with sham operation (HF + sham; n=20) and HF with treatment (HF + RSD; n=20) groups. The HF model was established by subcutaneous injection of isoproterenol; six weeks later, 1eft ventricular internal diameter at end-systole (LVIDs), left ventricular systolic posterior wall thickness (LVPWs), 1eft ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were measured. Plasma norepinephrine (NE), angiotensin II (Ang II) and aldosterone (ALD) levels were measured by ELISA. Myocardial collagen volume fraction (CVF) was determined by Masson's staining. Reverse transcription-quantitative polymerase chain reaction was used to determine the mRNA expression levels of ventricular transforming growth factor-β (TGF-β), connective tissue growth factor (CTGF) and microRNAs (miRs), including miR-29b, miR-30c and miR-133a. The results demonstrated that LVIDs and LVPWs in the HF + RSD group were significantly decreased compared with the HF + sham group. By contrast, LVFS and LVEF in the HF + RSD group were significantly increased compared with the HF + sham group. RSD significantly reduced the levels of plasma NE, Ang II and ALD. CVF in the HF + RSD group was reduced by 38.1% compared with the HF + sham group. Expression levels of TGF-β and CTGF were decreased, whereas those of miR-29b, miR-30c and miR-133a were increased, in the HF + RSD group compared with the HF + sham group. These results indicated that RSD alleviates isoproterenol-induced left ventricle remodeling potentially via downregulation of TGF-β/CTGF and upregulation of miR-29b, miR-30c and miR-133a. RSD may therefore be an effective non-drug therapy for the treatment of heart failure. PMID:28849013

[Determination of total, soluble and insoluble dietary fiber in foods by enzymatic-gravimetric method].

PubMed

Yang, X; Yang, Y; Zhou, R; Bian, L

2001-11-01

For studying the contents of dietary fiber in general foods and functional foods, a enzymatic-gravimetric method recommended by AOAC was established in our laboratory. The method for the determination of total, soluble and insoluble dietary fiber in foods and functional foods could be used for many other kind of foods. The relative standard deviations (RSD) of reproducibility between-run and within-run were 2.04%-7.85%, 3.42%-55.23% respectively. The repeatability of the methods was good, and the methods are suitable for many foods.

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.

Passive PE Sampling in Support of In Situ Remediation of Contaminated Sediments

DTIC Science & Technology

2015-08-01

control RPD relative percent difference RSD relative standard deviation SERDP Strategic Environmental Research and Development Program SOPs...sediments from 2 stations, each at 4 PCB spike levels, for four individual congeners was 22 ± 6 % relative standard deviation ( RSD ). Also, comparison of... RSD (Table 3). However, larger congeners (e.g., congeners #153 and 180) whose approach to equilibrium is less certain, based on small fractions of

Demonstration of the Gore Module for Passive Ground Water Sampling

DTIC Science & Technology

2014-06-01

ix ACRONYMS AND ABBREVIATIONS % RSD percent relative standard deviation 12DCA 1,2-dichloroethane 112TCA 1,1,2-trichloroethane 1122TetCA...Analysis of Variance ROD Record of Decision RSD relative standard deviation SBR Southern Bush River SVOC semi-volatile organic compound...replicate samples had a relative standard deviation ( RSD ) that was 20% or less. For the remaining analytes (PCE, cDCE, and chloroform), at least 70

Predictors of Renal Denervation Efficacy in the Treatment of Resistant Hypertension.

PubMed

Ripp, Tatiana M; Mordovin, Victor F; Pekarskiy, Stanislav E; Ryabova, Tamara R; Zlobina, Marina V; Baev, Andrei E; Anfinogenova, Yana; Popov, Sergey V

2015-12-01

The aims of the study were to evaluate the effects of renal sympathetic denervation (RSD) on the heart and to identify the predictors of RSD efficacy in patients with resistant arterial hypertension. The study comprised 60 RSD patients (54.6 ± 9.5 years) who received full-dose antihypertensive therapy (4.1 drugs) including diuretics. Initially, 58.6% of patients had abnormal left ventricular (LV) diastolic function. All patients received echocardiography before and 24 weeks after RSD. Renal sympathetic denervation was achieved through the endovascular radiofrequency ablation (RFA) of the renal arteries. Drug therapy continued for the entire period of observation. After RSD, all patients were retrospectively assigned to two groups: group 1 comprised patients (n = 22; 36.7%) in whom the myocardial mass (MM) of the left ventricle decreased by more than 10 g after RSD; group 2 comprised patients (n = 38; 63.3%) in whom LV MM increased or decreased by less than 10 g. Anthropometry, arterial blood pressure, heart rate, therapy, and LV end-diastolic dimensions (EDD) were comparable in these groups. After RSD, the values of office blood pressure significantly decreased and MM regressed by more than 10 g in 36.7% of patients; LV diastolic function normalized in 31% of patients, and diastolic dysfunction improved in 14% of patients. The study found the associations between the initial LV wall dimensions and LV MM changes. Unlike LV EDD, arterial blood pressure, or heart rate, the initial values of LV wall thickness predicted LV MM regress. #NCT01499810 https://clinicaltrials.gov/ct2/show/NCT01499810.

Quantitative sensory studies in complex regional pain syndrome type 1/RSD.

PubMed

Tahmoush, A J; Schwartzman, R J; Hopp, J L; Grothusen, J R

2000-12-01

Patients with complex regional pain syndrome type I (CRPSD1) may have thermal allodynia after application of a non-noxious thermal stimulus to the affected limb. We measured the warm, cold, heat-evoked pain threshold and the cold-evoked pain threshold in the affected area of 16 control patients and patients with complex regional pain syndrome type 1/RSD to test the hypothesis that allodynia results from an abnormality in sensory physiology. A contact thermode was used to apply a constant 1 degrees C/second increasing (warm and heat-evoked pain) or decreasing (cold and cold-evoked pain) thermal stimulus until the patient pressed the response button to show that a temperature change was felt by the patient. Student t test was used to compare thresholds in patients and control patients. The cold-evoked pain threshold in patients with CRPSD1/RSD (p <0.001) was significantly decreased when compared with the thresholds in control patients (i.e., a smaller decrease in temperature was necessary to elicit cold-pain in patients with CRPSD1/RSD than in control patients). The heat-evoked pain threshold in patients with CRPS1/RSD was (p <0.05) decreased significantly when compared with thresholds in control patients. The warm- and cold-detection thresholds in patients with CRPS1/RSD were similar to the thresholds in control patients. This study suggests that thermal allodynia in patients with CRPS1/RSD results from decreased cold-evoked and heat-evoked pain thresholds. The thermal pain thresholds are reset (decreased) so that non-noxious thermal stimuli are perceived to be pain (allodynia).

LIDAR Remote Sensing of Particulate Matter Emissions from On-Road Vehicles

NASA Astrophysics Data System (ADS)

Keislar, R. E.; Kuhns, H.; Mazzoleni, C.; Moosmuller, H.; Watson, J.

2002-12-01

DRI has developed a remote sensing method for on-road particulate matter emissions from gasoline-powered and diesel-powered vehicles called the Vehicle Emissions Remote Sensing System (VERSS). Remote sensing of gaseous pollutants in vehicle exhaust is a well-established, economical way to determine on-road emissions for thousands of vehicles per day. The VERSS adds a particulate matter channel to complement gaseous pollutant measurements. The VERSS uses 266-nm ultraviolet laser light to achieve greater sensitivity than visible light to sub-micrometer particles, where the greatest mass fraction has been reported. The VERSS system integrates the lidar channel with a commercial remote sensing device (RSD) for gaseous pollutants, and the RSD CO2 measurement can be used to estimate fuel-based particle mass emissions. We describe the interpretation and processing of lidar returns from field measurements taken by the combined VERSS during the Southern Nevada Air Quality Study (SNAQS), conducted in the Las Vegas area. With suitable assumptions regarding size distribution and particle composition, the lidar backscatter signal and the RSD yield three basic measurements of particulate matter in the exhaust plume. For each passing vehicle, these three channels are: 1) Columnar extinction in the infrared (IR at 3.9 micrometers) 2) Columnar extinction in the ultraviolet (UV at 266 nm) 3) Range-resolved backscatter at 266 nm (horizontal spatial resolution of 20-25 cm) The 3.9-micrometer channel is a good surrogate for absorption by elemental carbon (EC) in tailpipe emissions and has been utilized in previous studies. Opacity measurements at 266 nm provide optical extinction due to scattering from tailpipe organic carbon (OC) and EC emissions.

UFLC-ESI-MS/MS analysis of multiple mycotoxins in medicinal and edible Areca catechu.

PubMed

Liu, Hongmei; Luo, Jiaoyang; Kong, Weijun; Liu, Qiutao; Hu, Yichen; Yang, Meihua

2016-05-01

A robust, sensitive and reliable ultra fast liquid chromatography combined with electrospray ionization tandem mass spectrometry (UFLC-ESI-MS/MS) was optimized and validated for simultaneous identification and quantification of eleven mycotoxins in medicinal and edible Areca catechu, based on one-step extraction without any further clean-up. Separation and quantification were performed in both positive and negative modes under multiple reaction monitoring (MRM) in a single run with zearalanone (ZAN) as internal standard. The chromatographic conditions and MS/MS parameters were carefully optimized. Matrix-matched calibration was recommended to reduce matrix effects and improve accuracy, showing good linearity within wide concentration ranges. Limits of quantification (LOQ) were lower than 50 μg kg(-1), while limits of detection (LOD) were in the range of 0.1-20 μg kg(-1). The accuracy of the developed method was validated for recoveries, ranging from 85% to 115% with relative standard deviation (RSD) ≤14.87% at low level, from 75% to 119% with RSD ≤ 14.43% at medium level and from 61% to 120% with RSD ≤ 13.18% at high level, respectively. Finally, the developed multi-mycotoxin method was applied for screening of these mycotoxins in 24 commercial samples. Only aflatoxin B2 and zearalenone were found in 2 samples. This is the first report on the application of UFLC-ESI(+/-)-MS/MS for multi-class mycotoxins in A. catechu. The developed method with many advantages of simple pretreatment, rapid determination and high sensitivity is a proposed candidate for large-scale detection and quantification of multiple mycotoxins in other complex matrixes. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Simultaneous Analysis of Cannabinoid and Synthetic Cannabinoids in Dietary Supplements Using UPLC with UV and UPLC-MS-MS.

PubMed

Heo, Seok; Yoo, Geum Joo; Choi, Ji Yeon; Park, Hyoung Joon; Do, Jung-Ah; Cho, Sooyeul; Baek, Sun Young; Park, Sung-Kwan

2016-06-01

The primary purpose of this study was to develop and validate a method based on UPLC with UV and UPLC-MS-MS for the simultaneous analysis of different cannabinoids and synthetic cannabinoids in food as well as in herbal and dietary supplements. The limits of detection and quantitation of the method ranged from 0.1 to 0.3 and 0.3 to 0.9 μg/mL by UPLC with UV, respectively. The coefficient of determination was >0.999; the intra- and interday precision of the method were 0.1-3.7 and 0.9-4.1%, respectively. The intra- and interday accuracy were 94.8-103.1 and 98.3-100.9%, respectively. The mean recoveries of nine cannabinoids obtained from tablet samples ranged from 81.1 to 105.4%. The mean extraction recoveries of nine target cannabinoids obtained from various types of samples (tablets, capsules, powders, liquids, cookies and candies) ranged from 82.26 to 112.40%. The relative standard deviation (RSD) of the stability of the prepared sample solutions was <1.80%. Identification and quantification of the nine cannabinoids were accomplished by ion spray UPLC-MS-MS using multiple reaction monitoring. The UPLC-MS-MS method was validated for linearity (R(2) > 0.99); the precision was 0.1-4.0% (intraday) and 0.1-2.8% (interday), and the accuracy was 98.0-103.5% (intraday) and 97.1-103.2% (interday). The mean extraction recoveries of six types of samples were 82.2-114.5% and the RSD of stability was <6.54%, complying with the established international guidelines. The results indicated that the method can be used for rapid and accurate screening of cannabinoids present in food. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Validation of a method for the determination of zolpidem in human plasma using LC with fluorescence detection.

PubMed

Ring, P R; Bostick, J M

2000-04-01

A sensitive and selective high-performance liquid chromatography (HPLC) method was developed for the determination of zolpidem in human plasma. Zolpidem and the internal standard (trazodone) were extracted from human plasma that had been made basic. The basic sample was loaded onto a conditioned Bond Elut C18 cartridge, rinsed with water and eluted with methanol. Forty microliters were then injected onto the LC system. Separation was achieved on a C18 column (150 x 4.6 mm, 5 microm) with a mobile phase composed of acetonitrile:50 mM potassium phosphate monobasic at pH 6.0 (4:6, v/v). Detection was by fluorescence, with excitation at 254 nm and emission at 400 nm. The retention times of zolpidem and internal standard were approximately 4.7 and 5.3 min, respectively. The LC run time was 8 min. The assay was linear in concentration range 1-400 ng/ml for zolpidem in human plasma. The analysis of quality control samples for zolpidem (3, 30, and 300 ng/ml) demonstrated excellent precision with relative standard deviations (RSD) of 3.7, 4.6, and 3.0%, respectively (n = 18). The method was accurate with all intraday (n = 6) and overall (n = 18) mean concentrations within 5.8% from nominal at all quality control sample concentrations. This method was also performed using a Gilson Aspec XL automated sample processor and autoinjector. The samples were manually fortified with internal standard and made basic. The aspec then performed the solid phase extraction and made injections of the samples onto the LC system. Using the automated procedure for analysis, quality control samples for zolpidem (3, 30, and 300 ng/ml) demonstrated acceptable precision with RSD values of 9.0, 4.9, and 5.1%, respectively (n = 12). The method was accurate with all intracurve (n = 4) and overall (n = 12) mean values being less than 10.8% from nominal at all quality control sample concentrations.

Proof of concept study: renal sympathetic denervation for treatment of polymorphic premature ventricular complexes.

PubMed

Kiuchi, Márcio Galindo; E Silva, Gustavo Ramalho; Paz, Luis Marcelo Rodrigues; Chen, Shaojie; Souto, Gladyston Luiz Lima

2016-11-01

Polymorphic premature ventricular complexes (PVCs) are very common, appearing most frequently in patients with hypertension, obesity, sleep apnea, and structural heart disease. Sympathetic hyperactivity plays a critical role in the development, maintenance, and aggravation of ventricular arrhythmias. Recently, the relevance of sympathetic activation in patients with ventricular arrhythmias was reported, and this finding suggested a potential role for catheter-based renal sympathetic denervation in reducing the arrhythmic burden. We evaluated the effectiveness of the renal sympathetic denervation (RSD) in comparison to antiarrhythmic pharmacologic therapy in reducing polymorphic PVCs refractory to medication therapy and cardiac parameters assessed by 24-h Holter monitoring and cardiac magnetic resonance (CRM), respectively, in patients with structurally normal heart. Thirty-four patients were included in this study, 14 served as control, and 20 were treated with an ablation cardiac catheter with open irrigated tip. RSD was performed by a single operator following the standard technique. All the patients included had polymorphic PVCs and structurally normal heart. Data were obtained at baseline at the 12th month of follow-up (sixth month after RSD or adjustment of antiarrhythmic dosage). In RSD group, we observed a significant decrease in the number of polymorphic PVCs from baseline 36,091 ± 3327 to 3, 6, 7 (first month after RSD, without drugs), and 12 months (sixth month after RSD, without drugs) of follow-up, 31,009 ± 3251, 20,411 ± 3820, 7701 ± 1549, and 1274 ± 749, respectively, in all patients, P < 0.0001 to all the comparisons between the mean of each time point with the mean of every other time point. No changes in mean 24-h ABPM and renal function in both groups were observed at 12th month of follow-up. However, 24-h Holter mean heart rate decreased in control group at 12th month of follow-up, which did not happen with the RSD group. At the sixth month post-RSD in comparison to baseline, a significant reduction in the number of polymorphic PVCs (∆ = -34,817 ± 3590, P < 0.0001) was observed, as well as, in CRM parameters such as left ventricular mass/body surface area (∆ = -5.4 ± 2.1 g/m 2 , P < 0.0001) and left ventricular ejection fraction (∆ = +3.0 ± 1.8 %, P < 0.0001). In comparison to control group at the same time point, these findings were statistically superior in RSD group (P > 0.05). A significant correlation was found between the Δ number of polymorphic PVCs at the sixth month (r = -0.6723, P = 0.0012) after the RSD and the total number of RSD ablated spots. Polymorphic PVCs refractory to medication therapy may be modifiable by RSD in patients without structural heart disease. Although encouraging, our data are preliminary and need to be validated in a large population and in long term.

Analysis of adulterants in a traditional herbal medicinal product using liquid chromatography-mass spectrometry-mass spectrometry.

PubMed

Lau, Aik-Jiang; Holmes, Michael J; Woo, Soo-On; Koh, Hwee-Ling

2003-02-26

Adulterations with synthetic drugs are common problems with herbal medicine and this can potentially cause serious adverse effects. It is therefore important to determine the presence of synthetic drugs in herbal medicine to ensure patients' safety. The objective of this study was to develop sensitive and specific methods to analyse phenylbutazone, caffeine and oxyphenbutazone present in a traditional Indonesian herbal product. Liquid chromatography-mass spectrometry-mass spectrometry (LC-MS-MS) methods in the selected reaction-monitoring (SRM) mode were developed. It was found that the sample contained 0.53% w/w (n=3, RSD=7.56%) phenylbutazone and 0.04% w/w (n=3, RSD=8.39%) caffeine. This corresponded to 43.17 mg phenylbutazone and 3.23 mg caffeine in each sachet of powder. The methods were validated for linearity, precision, accuracy, LOD and LOQ. LOD and LOQ were found to be 3.69 and 12.29 ng/ml, respectively for phenylbutazone. For caffeine, the LOD and LOQ were 0.84 and 2.80 ng/ml, respectively. Oxyphenbutazone in the sample was found to be present at a level below the quantification level of 10.2 ng/ml. With better methods developed for analysis of adulterants in herbal medicine, the quality and safety of these medicines can be better controlled and regulated to ensure patients' safety.

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.

Identification and Quantification of Dimethylamylamine in Geranium by Liquid Chromatography Tandem Mass Spectrometry

PubMed Central

Li, J.S.; Chen, M.; Li, Z.C.

2012-01-01

A sensitive and reliable method of liquid chromatography–electrospray ionization/tandem mass spectrometry (LC-ESI/MS/ MS) was developed and validated for determining 1,3-dimethylamylamine (1,3-DMAA) and 1,4-dimethylamylamine (1,4-DMAA) in geranium plants (Pelargonium graveolens). The sample was extracted with 0.5 M HCl and purified by liquid-liquid partition with hexane. The parameters for reverse-phase (C18) LC and positive ESI/MS/MS were optimized. The matrix effect, specificity, linearity, precision, accuracy and reproducibility of the method were determined and evaluated. The method was linear over a range of 0.10–10.00 ng/mL examined, with R2 of 0.99 for both 1,3-DMAA and 1,4-DMAA. The recoveries from spiked concentrations between 5.00–40.00 ng/g were 85.1%–104.9% for 1,3-DMAA, with relative standard deviation (RSD) of 2.9%–11.0%, and 82.9%–101.8% for 1,4-DMAA, with RSD of 3.2%–11.7%. The instrument detection limit was 1–2 pg for both DMAAs. The quantification limit was estimated to be 1–2 ng/g for the plant sample. This method was successfully applied to the quantitative determination of 1,3- and 1,4-DMAA in both geranium plant and geranium oil. PMID:22915838

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.

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

Bürger, Stefan; Riciputi, Lee R; Bostick, Debra A

A ThermoFisher 'Triton' multi-collector thermal ionization mass spectrometer (MC-TIMS) was evaluated for trace and ultra-trace level isotoperatioanalysis of actinides (uranium, plutonium, and americium), fission products and geolocators (strontium, cesium, and neodymium). Total efficiencies (atoms loaded to ions detected) of up to 0.5-2% for U, Pu, and Am, and 1-30% for Sr, Cs, and Nd can be reported employing resin bead load techniques onto flat ribbon Re filaments or resin beads loaded into a millimeter-sized cavity drilled into a Re rod. This results in detection limits of <0.1 fg (10{sup 4} atoms to 10{sup 5} atoms) for {sup 239-242+244}Pu, {sup 233+236}U,more » {sup 241-243}Am, {sup 89,90}Sr, and {sup 134,135,137}Cs, and {le} 1 pg for natural Nd isotopes (limited by the chemical processing blank) using a secondary electron multiplier (SEM) or multiple-ion counters (MICs). Relative standard deviations (RSD) as small as 0.1% and abundance sensitivities of 1 x 10{sup 6} or better using a SEM are reported here. Precisions of RSD {approx} 0.01-0.001% using a multi-collector Faraday cup array can be achieved at sub-nanogram concentrations for strontium and neodymium and are suitable to gain crucial geolocation information. The analytical protocols reported herein are of particular value for nuclear forensic and nuclear safeguard applications.« less

Application of snapshot imaging spectrometer in environmental detection

NASA Astrophysics Data System (ADS)

Sun, Kai; Qin, Xiaolei; Zhang, Yu; Wang, Jinqiang

2017-10-01

This study aimed at the application of snapshot imaging spectrometer in environmental detection. The simulated sewage and dyeing wastewater were prepared and the optimal experimental conditions were determined. The white LED array was used as the detection light source and the image of the sample was collected by the imaging spectrometer developed in the laboratory to obtain the spectral information of the sample in the range of 400-800 nm. The standard curve between the absorbance and the concentration of the samples was established. The linear range of a single component of Rhoda mine B was 1-50 mg/L, the linear correlation coefficient was more than 0.99, the recovery was 93%-113% and the relative standard deviations (RSD) was 7.5%. The linear range of chemical oxygen demand (COD) standard solution was 50-900mg/L, the linear correlation coefficient was 0.981, the recovery was 91% -106% and the relative standard deviation (RSD) was 6.7%. The rapid, accurate and precise method for detecting dyes showed an excellent promise for on-site and emergency detection in environment. At the request of the proceedings editor, an updated version of this article was published on 17 October 2017. The original version of this article was replaced due to an accidental inversion of Figure 2 and Figure 3. The Figures have been corrected in the updated and republished version.

40 CFR Appendix A to Subpart A of... - Switcher Locomotives

Code of Federal Regulations, 2010 CFR

2010-07-01

... 6-539. S11 6-539. S12 6-539T. S13 6-251C. RSD-1 6-539. RSC-13 6-539. RSC-24 12-244 RS1 6-539T. RS2 1 12-244. RS3 1 12-244. RS10 1 12-244. RSC-2 1 12-244. RS3 1 12-244. RSD-4 1 12-244. RSD-5 1 12-244. T6...

40 CFR Appendix A to Subpart A of... - Switcher Locomotives

Code of Federal Regulations, 2011 CFR

2011-07-01

... 6-539. S11 6-539. S12 6-539T. S13 6-251C. RSD-1 6-539. RSC-13 6-539. RSC-24 12-244 RS1 6-539T. RS2 1 12-244. RS3 1 12-244. RS10 1 12-244. RSC-2 1 12-244. RS3 1 12-244. RSD-4 1 12-244. RSD-5 1 12-244. T6...

40 CFR Appendix A to Subpart A of... - Switcher Locomotives

Code of Federal Regulations, 2013 CFR

2013-07-01

... 6-539. S11 6-539. S12 6-539T. S13 6-251C. RSD-1 6-539. RSC-13 6-539. RSC-24 12-244 RS1 6-539T. RS2 1 12-244. RS3 1 12-244. RS10 1 12-244. RSC-2 1 12-244. RS3 1 12-244. RSD-4 1 12-244. RSD-5 1 12-244. T6...

40 CFR Appendix A to Subpart A of... - Switcher Locomotives

Code of Federal Regulations, 2012 CFR

2012-07-01

... 6-539. S11 6-539. S12 6-539T. S13 6-251C. RSD-1 6-539. RSC-13 6-539. RSC-24 12-244 RS1 6-539T. RS2 1 12-244. RS3 1 12-244. RS10 1 12-244. RSC-2 1 12-244. RS3 1 12-244. RSD-4 1 12-244. RSD-5 1 12-244. T6...

40 CFR Appendix A to Subpart A of... - Switcher Locomotives

Code of Federal Regulations, 2014 CFR

2014-07-01

... 6-539. S11 6-539. S12 6-539T. S13 6-251C. RSD-1 6-539. RSC-13 6-539. RSC-24 12-244 RS1 6-539T. RS2 1 12-244. RS3 1 12-244. RS10 1 12-244. RSC-2 1 12-244. RS3 1 12-244. RSD-4 1 12-244. RSD-5 1 12-244. T6...