Development and Validation of an Analytical Methodology Based on Liquid Chromatography-Electrospray Tandem Mass Spectrometry for the Simultaneous Determination of Phenolic Compounds in Olive Leaf Extract.

PubMed

Cittan, Mustafa; Çelik, Ali

2018-04-01

A simple method was validated for the analysis of 31 phenolic compounds using liquid chromatography-electrospray tandem mass spectrometry. Proposed method was successfully applied to the determination of phenolic compounds in an olive leaf extract and 24 compounds were analyzed quantitatively. Olive biophenols were extracted from olive leaves by using microwave-assisted extraction with acceptable recovery values between 78.1 and 108.7%. Good linearities were obtained with correlation coefficients over 0.9916 from calibration curves of the phenolic compounds. The limits of quantifications were from 0.14 to 3.2 μg g-1. Intra-day and inter-day precision studies indicated that the proposed method was repeatable. As a result, it was confirmed that the proposed method was highly reliable for determination of the phenolic species in olive leaf extracts.

Reverse phase HPLC method for detection and quantification of lupin seed γ-conglutin.

PubMed

Mane, Sharmilee; Bringans, Scott; Johnson, Stuart; Pareek, Vishnu; Utikar, Ranjeet

2017-09-15

A simple, selective and accurate reverse phase HPLC method was developed for detection and quantitation of γ-conglutin from lupin seed extract. A linear gradient of water and acetonitrile containing trifluoroacetic acid (TFA) on a reverse phase column (Agilent Zorbax 300SB C-18), with a flow rate of 0.8ml/min was able to produce a sharp and symmetric peak of γ-conglutin with a retention time at 29.16min. The identity of γ-conglutin in the peak was confirmed by mass spectrometry (MS/MS identification) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The data obtained from MS/MS analysis was matched against the specified database to obtain the exact match for the protein of interest. The proposed method was validated in terms of specificity, linearity, sensitivity, precision, recovery and accuracy. The analytical parameters revealed that the validated method was capable of selectively performing a good chromatographic separation of γ-conglutin from the lupin seed extract with no interference of the matrix. The detection and quantitation limit of γ-conglutin were found to be 2.68μg/ml and 8.12μg/ml respectively. The accuracy (precision and recovery) analysis of the method was conducted under repeatable conditions on different days. Intra-day and inter-day precision values less than 0.5% and recovery greater than 97% indicated high precision and accuracy of the method for analysis of γ-conglutin. The method validation findings were reproducible and can be successfully applied for routine analysis of γ-conglutin from lupin seed extract. Copyright © 2017 Elsevier B.V. All rights reserved.

The Intertemporal Stability of Teacher Effect Estimates. Working Paper 2008-22

ERIC Educational Resources Information Center

McCaffrey, Daniel F.; Sass, Tim R.; Lockwood, J.R.

2008-01-01

Recently, a number of school districts have begun using measures of teachers' contributions to student test scores or teacher "value added" to determine salaries and other monetary rewards. In this paper we investigate the precision of value-added measures by analyzing their inter-temporal stability. We find that these measures of…

Development and validation of RP HPLC method to determine nandrolone phenylpropionate in different pharmaceutical formulations.

PubMed

Mukherjee, Jayanti; Das, Ayan; Chakrabarty, Uday Sankar; Sahoo, Bijay Kumar; Dey, Goutam; Choudhury, Hira; Pal, Tapan Kumar

2011-01-01

This study describes development and subsequent validation of a reversed phase high performance liquid chromatographic (RP-HPLC) method for the estimation of nandrolone phenylpropionate, an anabolic steroid, in bulk drug, in conventional parenteral dosage formulation and in prepared nanoparticle dosage form. The chromatographic system consisted of a Luna Phenomenex, CN (250 mm x 4.6 mm, 5 microm) column, an isocratic mobile phase comprising 10 mM phosphate buffer and acetonitrile (50:50, v/v) and UV detection at 240 nm. Nandrolone phenylpropionate was eluted about 6.3 min with no interfering peaks of excipients used for the preparation of dosage forms. The method was linear over the range from 0.050 to 25 microg/mL in raw drug (r2 = 0.9994). The intra-day and inter-day precision values were in the range of 0.219-0.609% and 0.441-0.875%, respectively. Limits of detection and quantitation were 0.010 microg/mL and 0.050 microg/mL, respectively. The results were validated according to International Conference on Harmonization (ICH) guidelines in parenteral and prepared nanoparticle formulation. The validated HPLC method is simple, sensitive, precise, accurate and reproducible.

"Repeating Events" as Estimator of Location Precision: The China National Seismograph Network

NASA Astrophysics Data System (ADS)

Jiang, Changsheng; Wu, Zhongliang; Li, Yutong; Ma, Tengfei

2014-03-01

"Repeating earthquakes" identified by waveform cross-correlation, with inter-event separation of no more than 1 km, can be used for assessment of location precision. Assuming that the network-measured apparent inter-epicenter distance X of the "repeating doublets" indicates the location precision, we estimated the regionalized location quality of the China National Seismograph Network by comparing the "repeating events" in and around China by S chaff and R ichards (Science 303: 1176-1178, 2004; J Geophys Res 116: B03309, 2011) and the monthly catalogue of the China Earthquake Networks Center. The comparison shows that the average X value of the China National Seismograph Network is approximately 10 km. The mis-location is larger for the Tibetan Plateau, west and north of Xinjiang, and east of Inner Mongolia, as indicated by larger X values. Mis-location is correlated with the completeness magnitude of the earthquake catalogue. Using the data from the Beijing Capital Circle Region, the dependence of the mis-location on the distribution of seismic stations can be further confirmed.

Effects of inter- and intra-observer variability on echocardiographic measurements in awake cats.

PubMed

Chetboul, V; Concordet, D; Pouchelon, J L; Athanassiadis, N; Muller, C; Benigni, L; Munari, A C; Lefebvre, H P

2003-08-01

The objective of this study was to determine intra- and inter-observer variability of echocardiographic measurements in awake cats. Four observers with different levels of experience in echocardiography performed 96 echocardiographic examinations in four cats on four different days over a 3-week period. The examinations were randomized and blinded. The maximum within-day and between-day CV values were 17.4 and 18.5% for inter-ventricular septal thickness in diastole, 18.7 and 22.6% for left ventricular free-wall thickness in diastole, 9.8 and 14.9% for left ventricular end-diastolic diameter, 20.8 and 15.2% for left ventricular end-systolic diameter, and 21.2 and 18.4% for left ventricular shortening fraction. The maximum within-day CV values were most often associated with the least competent observer (i.e. the graduate student) and, the minimum CV values with the most competent observer (i.e. the associate professor in cardiology). A significant interaction between cat and observer was also evidenced. Thus, the most competent observer could not be replaced by any of the other observers.

Anodic Oxidation of Etodolac and its Linear Sweep, Square Wave and Differential Pulse Voltammetric Determination in Pharmaceuticals

PubMed Central

Yilmaz, B.; Kaban, S.; Akcay, B. K.

2015-01-01

In this study, simple, fast and reliable cyclic voltammetry, linear sweep voltammetry, square wave voltammetry and differential pulse voltammetry methods were developed and validated for determination of etodolac in pharmaceutical preparations. The proposed methods were based on electrochemical oxidation of etodolac at platinum electrode in acetonitrile solution containing 0.1 M lithium perchlorate. The well-defined oxidation peak was observed at 1.03 V. The calibration curves were linear for etodolac at the concentration range of 2.5-50 μg/ml for linear sweep, square wave and differential pulse voltammetry methods, respectively. Intra- and inter-day precision values for etodolac were less than 4.69, and accuracy (relative error) was better than 2.00%. The mean recovery of etodolac was 100.6% for pharmaceutical preparations. No interference was found from three tablet excipients at the selected assay conditions. Developed methods in this study are accurate, precise and can be easily applied to Etol, Tadolak and Etodin tablets as pharmaceutical preparation. PMID:26664057

Validation of a LC/MS method for the determination of gemfibrozil in human plasma and its application to a pharmacokinetic study

PubMed Central

Rower, Joseph E.; Bushman, Lane R.; Hammond, Kyle P.; Kadam, Rajendra S.; Aquilante, Christina L.

2011-01-01

Gemfibrozil, a fibric acid hypolipidemic agent, is increasingly being used in clinical drug-drug interaction studies as an inhibitor of drug metabolizing enzymes and drug transporters. The validation of a fast, accurate, and precise LC/MS method is described for the quantitative determination of gemfibrozil in an EDTA-anticoagulated human plasma matrix. Briefly, gemfibrozil was extracted from human plasma by an acetonitrile protein precipitation method. The assay was reproducible with intra-assay precision between 1.6% and 10.7%, and inter-assay precision ranging from 4.4% to 7.8%. The assay also showed good accuracy, with intra-assay concentrations within 85.6% and 108.7% of the expected value, and inter-assay concentrations within 89.4 to 104.0% of the expected value. The linear concentration range was between 0.5 and 50 μg/mL with a lower limit of quantitation of 0.5 μg/mL when 125 μL of plasma were extracted. This LC/MS method yielded a quick, simple, and reliable protocol for determining gemfibrozil concentrations in plasma and is applicable to clinical pharmacokinetic studies. PMID:21077249

Validation of an LC/MS method for the determination of gemfibrozil in human plasma and its application to a pharmacokinetic study.

PubMed

Rower, Joseph E; Bushman, Lane R; Hammond, Kyle P; Kadam, Rajendra S; Aquilante, Christina L

2010-12-01

Gemfibrozil, a fibric acid hypolipidemic agent, is increasingly being used in clinical drug-drug interaction studies as an inhibitor of drug metabolizing enzymes and drug transporters. The validation of a fast, accurate and precise LC/MS method is described for the quantitative determination of gemfibrozil in an EDTA-anticoagulated human plasma matrix. Briefly, gemfibrozil was extracted from human plasma by an acetonitrile protein precipitation method. The assay was reproducible with intra-assay precision between 1.6 and 10.7%, and inter-assay precision ranging from 4.4 to 7.8%. The assay also showed good accuracy, with intra-assay concentrations within 85.6-108.7% of the expected value, and inter-assay concentrations within 89.4-104.0% of the expected value. The linear concentration range was between 0.5 and 50 µg/mL with a lower limit of quantitation of 0.5 µg/mL when 125 µL of plasma were extracted. This LC/MS method yielded a quick, simple and reliable protocol for determining gemfibrozil concentrations in plasma and is applicable to clinical pharmacokinetic studies. Copyright © 2010 John Wiley & Sons, Ltd.

A portable system for foot biomechanical analysis during gait.

PubMed

Samson, William; Sanchez, Stéphane; Salvia, Patrick; Jan, Serge Van Sint; Feipel, Véronique

2014-07-01

Modeling the foot is challenging due to its complex structure compared to most other body segments. To analyze the biomechanics of the foot, portable devices have been designed to allow measurement of temporal, spatial, and pedobarographic parameters. The goal of this study was to design and evaluate a portable system for kinematic and dynamic analysis of the foot during gait. This device consisted of a force plate synchronized with four cameras and integrated into a walkway. The complete system can be packaged for transportation. First, the measurement system was assessed using reference objects to evaluate accuracy and precision. Second, nine healthy participants were assessed during gait trials using both the portable and Vicon systems (coupled with a force plate). The ankle and metatarsophalangeal (MP) joint angles and moments were computed, as well as the ground reaction force (GRF). The intra- and inter-subject variability was analyzed for both systems, as well as the inter-system variation. The accuracy and precision were, respectively 0.4 mm and 0.4 mm for linear values and 0.5° and 0.6° for angular values. The variability of the portable and Vicon systems were similar (i.e., the inter-system variability never exceeded 2.1°, 0.081 Nmkg(-1) and 0.267 Nkg(-1) for the angles, moments and GRF, respectively). The inter-system differences were less than the inter-subject variability and similar to the intra-subject variability. Consequently, the portable system was considered satisfactory for biomechanical analysis of the foot, outside of a motion analysis laboratory. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of QuEChERS-based extraction and liquid chromatography-tandem mass spectrometry method for quantifying flumethasone residues in beef muscle.

PubMed

Park, Ki Hun; Choi, Jeong-Heui; Abd El-Aty, A M; Cho, Soon-Kil; Park, Jong-Hyouk; Kwon, Ki Sung; Park, Hee Ra; Kim, Hyung Soo; Shin, Ho-Chul; Kim, Mi Ra; Shim, Jae-Han

2012-12-01

A rapid, specific, and sensitive method based on liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in the positive ion mode using multiple reaction monitoring (MRM) was developed and validated to quantify flumethasone residues in beef muscle. Methods were compared between the original as well as the EN quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based extraction. Good linearity was achieved at concentration levels of 5-30 μg/kg. Estimated recovery rates at spiking levels of 5 and 10 μg/kg ranged from 72.1 to 84.6%, with relative standard deviations (RSDs)<7%. The results of the inter-day study, which was performed by fortifying beef muscle samples (n=18) on 3 separate days, showed an accuracy of 93.4-94.4%. The precision (expressed as relative standard deviation values) for the inter-day variation at two levels of fortification (10 and 20 μg/kg) was 1.9-5.2%. The limit of detection (LOD) and limit of quantitation (LOQ) were 1.7 and 5 μg/kg, at signal-to-noise ratios (S/Ns) of 3 and 10, respectively. The method was successfully applied to analyze real samples obtained from large markets throughout the Korean Peninsula. The method proved to be sensitive and reliable and, thus, rendered an appropriate means for residue analysis studies. Copyright © 2012 Elsevier Ltd. All rights reserved.

Positioning stability improvement with inter-system biases on multi-GNSS PPP

NASA Astrophysics Data System (ADS)

Choi, Byung-Kyu; Yoon, Hasu

2018-07-01

The availability of multiple signals from different Global Navigation Satellite System (GNSS) constellations provides opportunities for improving positioning accuracy and initial convergence time. With dual-frequency observations from the four constellations (GPS, GLONASS, Galileo, and BeiDou), it is possible to investigate combined GNSS precise point positioning (PPP) accuracy and stability. The differences between GNSS systems result in inter-system biases (ISBs). We consider several ISB values such as GPS-GLONASS, GPS-Galileo, and GPS-BeiDou. These biases are compliant with key parameters defined in the multi-GNSS PPP processing. In this study, we present a unified PPP method that sets ISB values as fixed or constant. A comprehensive analysis that includes satellite visibility, position dilution of precision, position accuracy is performed to evaluate a unified PPP method with constrained cut-off elevation angles. Compared to the conventional PPP solutions, our approach shows more stable positioning at a constrained cut-off elevation angle of 50 degrees.

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.

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.

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.

[Determination of four bisphenolic compounds in drinking water by liquid chromatography-tandem mass spectrometry].

PubMed

Hu, Xiaojian; Zhang, Haijing; Wang, Xiaohong; Ding, Changming; Lin, Shaobin

2015-05-01

To simultaneously determine the four bisphenolic compounds (bisphenol F, bisphenol A, tetrachlorobisphenol A and tetrabromobisphenol A) in drinking water by liquid chromatography tandem mass spectrometry. 200 ml water sample was extracted by solid-phase extraction, eluted with methanol and analyzed by liquid chromatography tandem mass spectrometry under the MRM mode. The separation was carried out on a T3 column (2.1 mm x 150 mm, 3 μm). The limits of detection for the four bisphenolic compounds were in the range of 0.20 - 5.5 ng/L. The mean recoveries at the two spiked levels were 87.1% - 109.0% with the intra-day precision between 6.3% - 12.4% and inter-day precision between 4.5% - 15.4%. The method was applied for determination of 15 water samples. The method was sensitive, precise and accurate.

Reliability of diabetic patients' gait parameters in a challenging environment.

PubMed

Allet, L; Armand, S; de Bie, R A; Golay, A; Monnin, D; Aminian, K; de Bruin, E D

2008-11-01

Activities of daily life require us to move about in challenging environments and to walk on varied surfaces. Irregular terrain has been shown to influence gait parameters, especially in a population at risk for falling. A precise portable measurement system would permit objective gait analysis under such conditions. The aims of this study are to (a) investigate the reliability of gait parameters measured with the Physilog in diabetic patients walking on different surfaces (tar, grass, and stones); (b) identify the measurement error (precision); (c) identify the minimal clinical detectable change. 16 patients with Type 2 diabetes were measured twice within 8 days. After clinical examination patients walked, equipped with a Physilog, on the three aforementioned surfaces. ICC for each surface was excellent for within-visit analyses (>0.938). Inter-visit ICC's (0.753) were excellent except for the knee range parameter (>0.503). The coefficient of variation (CV) was lower than 5% for most of the parameters. Bland and Altman Plots, SEM and SDC showed precise values, distributed around zero for all surfaces. Good reliability of Physilog measurements on different surfaces suggests that Physilog could facilitate the study of diabetic patients' gait in conditions close to real-life situations. Gait parameters during complex locomotor activities (e.g. stair-climbing, curbs, slopes) have not yet been extensively investigated. Good reliability, small measurement error and values of minimal clinical detectable change recommend the utilization of Physilog for the evaluation of gait parameters in diabetic patients.

Comparison of UPLC and HPLC methods for determination of vitamin C.

PubMed

Klimczak, Inga; Gliszczyńska-Świgło, Anna

2015-05-15

Ultra performance liquid chromatography (UPLC) and high-performance liquid chromatography (HPLC) methods for determination of ascorbic acid (AA) and total AA (TAA) contents (as the sum of AA and dehydroascorbic acid (DHAA) after its reduction to AA) in fruit beverages and in pharmaceutical preparations were compared. Both methods are rapid: total time of analysis was 15 and 6 min for HPLC and UPLC methods, respectively. The methods were validated in terms of linearity, instrument precision, limits of detection (LOD) and quantification (LOQ), accuracy and recovery. Intra- and inter-day instrument precisions for fruit juices, expressed as RSD, were 2.2% and 2.4% for HPLC, respectively, and 1.7% and 1.9% for UPLC, respectively. For vitamin C tablets, inter- and intra-day precisions were 0.4% and 0.5%, respectively (HPLC), and 0.5% and 0.3%, respectively (UPLC). Both methods were sensitive: LOD was 0.049 μg/mL for HPLC and 0.024 μg/mL for UPLC while LOQs were 0.149 and 0.073 μg/mL for HPLC and UPLC, respectively. These methods could be useful in the routine qualitative and quantitative analysis of AA or TAA in pharmaceutical preparations or fruit beverages. However, UPLC method is more sensitive, faster and consumes less eluent. Copyright © 2014 Elsevier Ltd. All rights reserved.

Determination of Bosentan in Pharmaceutical Preparations by Linear Sweep, Square Wave and Differential Pulse Voltammetry Methods

PubMed Central

Atila, Alptug; Yilmaz, Bilal

2015-01-01

In this study, simple, fast and reliable cyclic voltammetry (CV), linear sweep voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) methods were developed and validated for determination of bosentan in pharmaceutical preparations. The proposed methods were based on electrochemical oxidation of bosentan at platinum electrode in acetonitrile solution containing 0.1 M TBACIO4. The well-defined oxidation peak was observed at 1.21 V. The calibration curves were linear for bosentan at the concentration range of 5-40 µg/mL for LSV and 5-35 µg/mL for SWV and DPV methods, respectively. Intra- and inter-day precision values for bosentan were less than 4.92, and accuracy (relative error) was better than 6.29%. The mean recovery of bosentan was 100.7% for pharmaceutical preparations. No interference was found from two tablet excipients at the selected assay conditions. Developed methods in this study are accurate, precise and can be easily applied to Tracleer and Diamond tablets as pharmaceutical preparation. PMID:25901151

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

PubMed

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

2015-04-15

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

UV Spectrophotometric Determination and Validation of Hydroquinone in Liposome.

PubMed

Khoshneviszadeh, Rabea; Fazly Bazzaz, Bibi Sedigheh; Housaindokht, Mohammad Reza; Ebrahim-Habibi, Azadeh; Rajabi, Omid

2015-01-01

The method has been developed and validated for the determination of hydroquinone in liposomal formulation. The samples were dissolved in methanol and evaluated in 293 nm. The validation parameters such as linearity, accuracy, precision, specificity, limit of detection (LOD) and limit of quantitation (LOQ) were determined. The calibration curve was linear in 1-50 µg/mL range of hydroquinone analyte with a regression coefficient of 0.9998. This study showed that the liposomal hydroquinone composed of phospholipid (7.8 %), cholesterol (1.5 %), alpha ketopherol (0.17 %) and hydroquinone (0.5 %) did not absorb wavelength of 293 nm if it diluted 500 times by methanol. The concentration of hydroquinone reached 10 µg/mL after 500 times of dilution. Furthermore, various validation parameters as per ICH Q2B guideline were tested and found accordingly. The recovery percentages of liposomal hydroquinone were found 102 ± 0.8, 99 ± 0.2 and 98 ± 0.4 for 80%, 100% and 120% respectively. The relative standard deviation values of inter and intra-day precisions were <%2. LOD and LOQ were 0.24 and 0.72 µg/mL respectively.

Determination of bosentan in pharmaceutical preparations by linear sweep, square wave and differential pulse voltammetry methods.

PubMed

Atila, Alptug; Yilmaz, Bilal

2015-01-01

In this study, simple, fast and reliable cyclic voltammetry (CV), linear sweep voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) methods were developed and validated for determination of bosentan in pharmaceutical preparations. The proposed methods were based on electrochemical oxidation of bosentan at platinum electrode in acetonitrile solution containing 0.1 M TBACIO4. The well-defined oxidation peak was observed at 1.21 V. The calibration curves were linear for bosentan at the concentration range of 5-40 µg/mL for LSV and 5-35 µg/mL for SWV and DPV methods, respectively. Intra- and inter-day precision values for bosentan were less than 4.92, and accuracy (relative error) was better than 6.29%. The mean recovery of bosentan was 100.7% for pharmaceutical preparations. No interference was found from two tablet excipients at the selected assay conditions. Developed methods in this study are accurate, precise and can be easily applied to Tracleer and Diamond tablets as pharmaceutical preparation.

Development and validation of RP-HPLC method: scope of application in the determination of oil solubility of paclitaxel.

PubMed

Choudhury, Hira; Gorain, Bapi; Karmakar, Sanmoy; Pal, Tapan Kumar

2014-01-01

A simple, reproducible, feasible and innovative reversed-phase high-performance liquid chromatographic method was developed and validated for the quantitative determination of paclitaxel dissolved in various oils. The method was validated after extraction of the analyte from capryol 90, triacetin and olive oil. The method was conducted on a Hypersil BDS C18 column, 250 × 4.6 mm, 5 µm particle size, with a mobile phase composed of acetonitrile: 10 mM KH2PO4 buffer (pH 3.5) (55:45, v/v) and detection at 227 nm. The linearity, in the range of 5 to 50 µg/mL, presented determination coefficients of 0.9983, 0.9997 and 0.9990 in capryol 90, triacetin and olive oil, respectively, calculated by the least-squares regression method. Intra-day precision values for percentages recovered were 0.68 to 0.80, 0.83 to 1.13 and 0.97 to 1.88, and inter day precision values were 1.52 to 1.92, 1.43 to 1.83 and 1.26 to 2.06 for capryol 90, triacetin and olive oil, respectively. The recovery of paclitaxel from the capryol 90, triacetin and olive oil ranged from 97.94 to 103.55, 96.85 to 103.27 and 97.14 to 103.64%, respectively. This developed and validated method was successfully applied to quantitatively assess paclitaxel dissolved in various oils. The solubility of paclitaxel was found to be higher in triacetin than in other tested oils.

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.

Cervical motion assessment using virtual reality.

PubMed

Sarig-Bahat, Hilla; Weiss, Patrice L; Laufer, Yocheved

2009-05-01

Repeated measures of cervical motion in asymptomatic subjects. To introduce a virtual reality (VR)-based assessment of cervical range of motion (ROM); to establish inter and intratester reliability of the VR-based assessment in comparison with conventional assessment in asymptomatic individuals; and to evaluate the effect of a single VR session on cervical ROM. Cervical ROM and clinical issues related to neck pain is frequently studied. A wide variety of methods is available for evaluation of cervical motion. To date, most methods rely on voluntary responses to an assessor's instructions. However, in day-to-day life, head movement is generally an involuntary response to multiple stimuli. Therefore, there is a need for a more functional assessment method, using sensory stimuli to elicit spontaneous neck motion. VR attributes may provide a methodology for achieving this goal. A novel method was developed for cervical motion assessment utilizing an electromagnetic tracking system and a VR game scenario displayed via a head mounted device. Thirty asymptomatic participants were assessed by both conventional and VR-based methods. Inter and intratester repeatability analyses were performed. The effect of a single VR session on ROM was evaluated. Both assessments showed non-biased results between tests and between testers (P > 0.1). Full-cycle repeatability coefficients ranged between 15.0 degrees and 29.2 degrees with smaller values for rotation and for the VR assessment. A single VR session significantly increased ROM, with largest effect found in the rotation direction. Inter and intratester reliability was supported for both the VR-based and the conventional methods. Results suggest better repeatability for the VR method, with rotation being more precise than flexion/extension. A single VR session was found to be effective in increasing cervical motion, possibly due to its motivating effect.

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

PubMed

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

2015-04-03

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

Quantification and clinical application of carboplatin in plasma ultrafiltrate.

PubMed

Downing, Kim; Jensen, Berit Packert; Grant, Sue; Strother, Matthew; George, Peter

2017-05-10

Carboplatin is a chemotherapy drug used in a variety of cancers with the primary toxicity being exposure-dependant myelosuppression. We present the development and validation of a simple, robust inductively coupled plasma mass spectrometry (ICP-MS) method to measure carboplatin in plasma ultrafiltrate. Plasma ultrafiltrates samples were prepared using Amicon Ultra 30,000da cut-off filters and then diluted with ammonia EDTA before ICP-MS analysis. The assay was validated in the range 0.19-47.5mg/L carboplatin in ultrafiltrate. The assay was linear (r 2 >0.9999), accurate (<6% bias, 12% bias at LLOQ) and precise (intra- and inter-day precision of <3% coefficient of variation). No matrix effects were observed between plasma ultrafiltrate and aqueous platinum calibrators and recovery was complete. The assay was applied to 10 clinical samples from patients receiving carboplatin. Incurred sample reanalysis showed reproducible values over 3 analysis days (<6% CV). As plasma stability prior to ultrafiltration has been a major concern in previous clinical studies this was studied extensively at room temperature (22°C) over 24h. Carboplatin was found to be stable in both spiked plasma (n=3) and real patient samples (n=10) at room temperature for up to 8h before ultrafiltration. This makes routine measurement of carboplatin concentrations in clinical settings feasible. Copyright © 2017 Elsevier B.V. All rights reserved.

A rapid method for the simultaneous determination of 25 anti-hypertensive compounds in dietary supplements using ultra-high-pressure liquid chromatography.

PubMed

Heo, Seok; Yoo, Geum Joo; Choi, Ji Yeon; Park, Hyoung Joon; Park, Sung-Kwan; Baek, Sun Young

2016-11-01

A novel, stable, simple and specific ultra-performance liquid chromatography method with ultraviolet detection (205 nm) for the simultaneous analysis of 25 anti-hypertensive substances was developed. The method was validated according to the International Conference of Harmonisation guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and stability. From the ultra-performance liquid chromatography results, we identified the LOD and LOQ of solid samples to be 0.20-1.00 and 0.60-3.00 μg ml -1 , respectively, while those of liquid samples were 0.30-1.20 and 0.90-3.60 μg ml -1 , respectively. The linearity exceeded 0.9999, and the intra- and inter-day precisions were 0.15-6.48% and 0.28-8.67%, respectively. The intra- and inter-day accuracies were 82.25-111.42% and 80.70-115.64%, respectively, and the stability was lower than 12.9% (relative standard deviation). This method was applied to the monitoring of 97 commercially available dietary supplements obtained in Korea, such as pills, soft capsules, hard capsules, liquids, powders and tablets. The proposed method is accurate, precise and of high quality, and can be used for the routine, reproducible analysis and control of 25 anti-hypertensive substances in various dietary supplements. The work presented herein may help to prevent incidents related to food adulteration and restrict the illegal food market.

[Application of asymmetrical flow field-flow fractionation for size characterization of low density lipoprotein in egg yolk plasma].

PubMed

Zhang, Wenhui; Cai, Chunxue; Wang, Jing; Mao, Zhen; Li, Yueqiu; Ding, Liang; Shen, Shigang; Dou, Haiyang

2017-08-08

Home-made asymmetrical flow field-flow fractionation (AF4) system, online coupled with ultraviolet/visible (UV/Vis) detector was employed for the separation and size characterization of low density lipoprotein (LDL) in egg yolk plasma. At close to natural condition of egg yolk, the effects of cross flow rate, sample loading, and type of membrane on the size distribution of LDL were investigated. Under the optimal operation conditions, AF4-UV/Vis provides the size distribution of LDL. Moreover, the precision of AF4-UV/Vis method proposed in this work for the analysis of LDL in egg yolk plasma was evaluated. The intra-day precisions were 1.3% and 1.9% ( n =7) and the inter-day precisions were 2.4% and 2.3% ( n =7) for the elution peak height and elution peak area of LDL, respectively. Results reveal that AF4-UV/Vis is a useful tool for the separation and size characterization of LDL in egg yolk plasma.

Optimization of a multiple headspace sorptive extraction method coupled to gas chromatography-mass spectrometry for the determination of volatile compounds in macroalgae.

PubMed

Maruti, Astrid; Durán-Guerrero, Enrique; Barroso, Carmelo G; Castro, Remedios

2018-05-25

A novel extraction technique is proposed in which the Multiple Headspace Extraction (MHE) approach is used in conjunction with Headspace Sorptive Extraction (HSSE) and Gas Chromatography-Mass Spectrometry (GC-MS) detection. The extraction method was developed to determine volatile compounds in macroalgae. Optimization of the extraction parameters was carried out using design of experiments to identify factors that affect the extraction: extraction time, temperature, twister length and amount of sample. The results of the optimization led to an extraction of 2 g of sample using a 20 mm Twister ® at 66 °C for 180 min. The progression constants (β) were calculated for 43 volatile compounds, 29 of which could be quantified using the method. Linearity was attained with a determination coefficient higher than 0.99 for all studied compounds. Inter-day and inter-twister precisions ranged from 0.22% to 19.01% and from 0.69% to 14.76% respectively, and values below 10% were obtained for the majority of compounds. LOD and LOQ values ranged from the values obtained for diethyl succinate (0.012 μg/L and 0.088 μg/L, respectively) and those obtained for dimethyl sulfide (5.544 μg/L and 40.286 μg/L, respectively). However, for the majority of compounds values obtained were below 1 μg/L (LOD) and 5 μg/L (LOQ). Compounds such as ethyl acetate, hexanal, heptadecane, 2-hexenal, 6-methyl-5-hepten-2-one, dimethyl sulfide, benzyl alcohol, beta ionone, or beta cyclocitral, among others were correctly determined in three species of macroalgae: Ulva sp., Gracillaria sp. and Enteromorpha sp. Copyright © 2018 Elsevier B.V. All rights reserved.

Quantitation of Pyrantel Pamoate in Pharmaceuticals Using Permanganate by Visible Spectrophotometry

NASA Astrophysics Data System (ADS)

Rajendraprasad, N.; Basavaiah, K.

2014-03-01

Two simple, accurate and precise spectrophotometric methods are developed and validated for the assay of pyrantel pamoate (PP) in pharmaceuticals. The methods employ the oxidative property of potassium permanganate (KMnO4) in acidic and alkaline conditions. In the first method (method A), PP is converted into its free base, pyrantel (PR), and treated with known excess of KMnO4 in acidic condition followed by the measurement of unreacted KMnO4 at 550 nm. Method B is based on the registration of absorbance of green colored chromogen formed due to the reduction of KMnO4 by PP in alkaline condition. The methods obeyed Beer's law over a range of 1-20 μg/ml in inverse manner, and 0.75-15 μg/ml for method A and method B, respectively, with apparent molar absorptivity values of 1.05ṡ104 and 2.85ṡ104 lṡmol-1ṡcm-1. The optical parameters such as limits of detection (LOD), quantification (LOQ), and the Sandell sensitivity values are also reported. The accuracy and precision of the methods are assessed on intra- and inter-day basis. A recovery study by standard addition procedure is also carried out for further assurance of accuracy. The developed methods are successfully applied to determine PP in tablets. The results are more satisfactory as per current ICH guidelines.

A validated HPLC-PDA method for identification and quantification of two bioactive alkaloids, ephedrine and cryptolepine, in different Sida species.

PubMed

Chatterjee, Arnab; Kumar, Satyanshu; Chattopadhyay, Sunil K

2013-12-01

A simple, rapid, accurate and reproducible reverse-phase HPLC method has been developed for the identification and quantification of two alkaloids ephedrine and cryptolepine in different extracts of Sida species using photodiode array detection. Baseline separation of the two alkaloids was achieved on a Waters RP-18 X-terra column (250 × 4.6 mm, 5 µm) using a solvent system consisting of a mixture of water containing 0.1% Trifluoroacetic acid (TFA) and acetonitrile in a gradient elution mode with detection at 210 and 280 nm for ephedrine and cryptolepine, respectively. The calibration curves were linear in a concentration range of 10-250 µg/mL for both the alkaloids with correlation coefficient values >0.99. The limits of detection and quantification for ephedrine and cryptolepine were 5 and 10 µg/mL and 2.5 and 5 µg/mL, respectively. Relative standard deviation values for intra-day and inter-day precision were 1.22 and 1.04% for ephedrine and 1.71 and 2.06% for cryptolepine, respectively. Analytical recovery ranged from 92.46 to 103.95%. The developed HPLC method was applied to identify and quantify ephedrine and cryptolepine in different extracts of Sida species. Copyright © 2013 John Wiley & Sons, Ltd.

LC-MS/MS method for the determination of clodronate in human plasma.

PubMed

Hasan, Mahmoud; Schumacher, Gitta; Seekamp, Anne; Taedken, Tobias; Siegmund, Werner; Oswald, Stefan

2014-11-01

Clodronate belongs to the class of bisphosphonates which are used for the treatment of bone disorders. Due to its high polarity it has a low and highly variable oral bioavailability which results in low plasma concentrations and requires sensitive bioanalytical methods to characterize its pharmacokinetics in human. Here, we describe for the first time the development and validation of a LC-MS/MS assay for the quantification of clodronate in human plasma. The bisphosphonate was isolated from the biological matrix by protein precipitation using perchloric acid (10%), and derivatized with trimethylorthoacetate prior sample clean-up with liquid-liquid extraction using methyl tert-butyl ether. The chromatography was performed using an isocratic elution with ammonium acetate 5mM (85% v/v, pH 3.8) and acetonitrile (15% v/v) as mobile phase with a flow rate of 300μl/min on a reversed-phase column (Supelco Ascentis(®), C18) temporized at 50°C. The mass spectrometric detection was done using the API4000 triple quadruple mass spectrometer monitoring the mass/charge transitions 301.0/145 for clodronate and 305.2/137.1 for the internal standard etidronate. The analytical range was set to 5-800ng/ml, allowing an evaluation of the plasma concentration-time profiles of clodronate for approximately 7-8 half-life (∼24h). The method was validated according to current FDA/EMA guidelines on bioanalytical method validation with respect to specificity, linearity, intra- and inter-day accuracy and precision, matrix effect, recovery as well as stability. The precision of the assay was 0.6-6.9% and 0.6-8.1% for the intra-day and inter-day variability, respectively. The intra-day and inter-day accuracy (error) was 0.6-8.8% and 2.2-4.5%. The recovery of the analyte was low (2-3%) but reproducible over the entire validation range and sufficient to monitor the target concentrations in human plasma. The drug was shown to be stable in plasma at room temperature for at least 3h (96.0±6%) and for at least 24h when stored in the cooled autosampler at 4°C (102.4±4.5%). Clodronate can also undergo up to three freeze-thaw cycles without impaired stability. Thus, the method was shown to possess sufficient specificity, sensitivity, accuracy, precision and stability to measure plasma concentrations of clodronate. Finally, the developed method was successfully applied to study the clodronate serum levels in a pharmacokinetic study in healthy volunteers. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of phosphonoformate (foscarnet) in calf and human serum by automated solid-phase extraction and high-performance liquid chromatography with amperometric detection.

PubMed

Ba, B B; Corniot, A G; Ducint, D; Breilh, D; Grellet, J; Saux, M C

1999-03-05

An isocratic high-performance liquid chromatographic method with automated solid-phase extraction has been developed to determine foscarnet in calf and human serums. Extraction was performed with an anion exchanger, SAX, from which the analyte was eluted with a 50 mM potassium pyrophosphate buffer, pH 8.4. The mobile phase consisted of methanol-40 mM disodium hydrogenphosphate, pH 7.6 containing 0.25 mM tetrahexylammonium hydrogensulphate (25:75, v/v). The analyte was separated on a polyether ether ketone (PEEK) column 150x4.6 mm I.D. packed with Kromasil 100 C18, 5 microm. Amperometric detection allowed a quantification limit of 15 microM. The assay was linear from 15 to 240 microM. The recovery of foscarnet from calf serum ranged from 60.65+/-1.89% for 15 microM to 67.45+/-1.24% for 200 microM. The coefficient of variation was < or = 3.73% for intra-assay precision and < or =7.24% for inter-assay precision for calf serum concentrations ranged from 15 to 800 microM. For the same samples, the deviation from the nominal value ranged from -8.97% to +5.40% for same day accuracy and from -4.50% to +2.77% for day-to-day accuracy. Selectivity was satisfactory towards potential co-medications. Replacement of human serum by calf serum for calibration standards and quality control samples was validated. Automation brought more protection against biohazards and increase in productivity for routine monitoring and pharmacokinetic studies.

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

PubMed

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

2010-09-01

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

Liquid chromatography/tandem mass spectrometry method for simultaneous determination of cocaine and its metabolite (-)ecgonine methyl ester in human acidified stabilized plasma samples.

PubMed

Liu, Yongzhen; Zheng, Bo; Strafford, Stephanie; Orugunty, Ravi; Sullivan, Michael; Gus, Jeffrey; Heidbreder, Christian; Fudala, Paul J; Nasser, Azmi

2014-06-15

Two simple, sensitive and rapid liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) methods (low range and high range) were developed and validated for the quantification of cocaine and its metabolite (-)ecgonine methyl ester (EME) in human acidified stabilized plasma samples. In the low range assay, cocaine and the internal standard, cocaine-D3, were extracted using a single step liquid-liquid extraction from human acidified stabilized plasma. For the high range assay, human acidified stabilized plasma containing cocaine, EME, and the internal standards, cocaine-D3 and EME-D3, was mixed with acetonitrile, and the protein precipitate was separated by centrifugation. Both cocaine and EME extracted from both assays were separated on a HILIC column and detected in positive ion mode using multiple reaction monitoring (MRM). Both methods were validated and the specificity, linearity, lower limit of quantitation (LLOQ), precision, accuracy, recoveries and stability were determined. The linear range for the low range assay was 0.01-5ng/mL for cocaine; in the high range assay values were 5-1000ng/mL for cocaine and 1-200ng/mL for EME. The correlation coefficient (R(2)) values for both assays were 0.993 or greater. The precision and accuracy for intra-day and inter-day were better than 13.0%. The recovery was above 85% and matrix effects were low with the matrix factor ranging from 0.817 to 1.10 for both analytes in both assays. The validated methods were successfully used to quantify the plasma concentrations of cocaine and EME in clinical pharmacokinetic and pharmacodynamic studies. Copyright © 2014 Elsevier B.V. All rights reserved.

Inter-examination Precision of Magnitude-based Magnetic Resonance Imaging for Estimation of Segmental Hepatic Proton Density Fat Fraction (PDFF) in Obese Subjects

PubMed Central

Negrete, Lindsey M.; Middleton, Michael S.; Clark, Lisa; Wolfson, Tanya; Gamst, Anthony C.; Lam, Jessica; Changchien, Chris; Deyoung-Dominguez, Ivan M.; Hamilton, Gavin; Loomba, Rohit; Schwimmer, Jeffrey; Sirlin, Claude B.

2013-01-01

Purpose To prospectively describe magnitude-based multi-echo gradient-echo hepatic proton density fat fraction (PDFF) inter-examination precision at 3T. Materials and Methods In this prospective, IRB approved, HIPAA compliant study, written informed consent was obtained from 29 subjects (body mass indexes > 30kg/m2). Three 3T magnetic resonance imaging (MRI) examinations were obtained over 75-90 minutes. Segmental, lobar, and whole liver PDFF were estimated (using three, four, five, or six echoes) by magnitude-based multi-echo MRI in co-localized regions of interest (ROIs). For estimate (using three, four, five, or six echoes), at each anatomic level (segmental, lobar, whole liver), three inter-examination precision metrics were computed: intra-class correlation coefficient (ICC), standard deviation (SD), and range. Results Magnitude-based PDFF estimates using each reconstruction method showed excellent inter-examination precision for each segment (ICC ≥ 0.992; SD ≤ 0.66%; range ≤ 1.24%), lobe (ICC ≥ 0.998; SD ≤ 0.34%; range ≤ 0.64%), and the whole liver (ICC = 0.999; SD ≤ 0.24%; range ≤ 0.45%). Inter-examination precision was unaffected by whether PDFF was estimated using three, four, five, or six echoes. Conclusion Magnitude-based PDFF estimation shows high inter-examination precision at segmental, lobar, and whole liver anatomic levels, supporting its use in clinical care or clinical trials. The results of this study suggest that longitudinal hepatic PDFF change greater than 1.6% is likely to represent signal rather than noise. PMID:24136736

Determination of ractopamine in pig hair using liquid chromatography with tandem mass spectrometric detection.

PubMed

Wu, Junlin; Liu, Xiaoyun; Peng, Yunping

2014-01-01

A quantitative analytical procedure for the determination of ractopamine in pig hair has been developed and validated. The hair samples were washed and incubated at 75°C with isoxuprine and hair extraction buffer. The drug present was quantified using mixed solid-phase extraction and liquid chromatography with tandem mass spectrometric detection. The limit of quantization (LOQ) was 10pg/mg and the intra-day precision at 25pg/mg and 750pg/mg was 0.49% and 2.8% respectively. Inter-day precision was 0.88% and 3.52% at the same concentrations. The hair extraction percentage recovery at 25pg/mg and 50ng/mL was 99.47% and 103.83% respectively. The extraction percentage recovery at 25pg/mg and 50ng/mg was 93.52% and 100.26% respectively. Our results showed that ractopamine residues persist in hair in 24days of withdrawal and also showed the possibility to test ractopamine from pig hair samples. Copyright © 2014 Elsevier Inc. All rights reserved.

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.

Operator Variability in Scan Positioning is a Major Component of HR-pQCT Precision Error and is Reduced by Standardized Training

PubMed Central

Bonaretti, Serena; Vilayphiou, Nicolas; Chan, Caroline Mai; Yu, Andrew; Nishiyama, Kyle; Liu, Danmei; Boutroy, Stephanie; Ghasem-Zadeh, Ali; Boyd, Steven K.; Chapurlat, Roland; McKay, Heather; Shane, Elizabeth; Bouxsein, Mary L.; Black, Dennis M.; Majumdar, Sharmila; Orwoll, Eric S.; Lang, Thomas F.; Khosla, Sundeep; Burghardt, Andrew J.

2017-01-01

Introduction HR-pQCT is increasingly used to assess bone quality, fracture risk and anti-fracture interventions. The contribution of the operator has not been adequately accounted in measurement precision. Operators acquire a 2D projection (“scout view image”) and define the region to be scanned by positioning a “reference line” on a standard anatomical landmark. In this study, we (i) evaluated the contribution of positioning variability to in vivo measurement precision, (ii) measured intra- and inter-operator positioning variability, and (iii) tested if custom training software led to superior reproducibility in new operators compared to experienced operators. Methods To evaluate the operator in vivo measurement precision we compared precision errors calculated in 64 co-registered and non-co-registered scan-rescan images. To quantify operator variability, we developed software that simulates the positioning process of the scanner’s software. Eight experienced operators positioned reference lines on scout view images designed to test intra- and inter-operator reproducibility. Finally, we developed modules for training and evaluation of reference line positioning. We enrolled 6 new operators to participate in a common training, followed by the same reproducibility experiments performed by the experienced group. Results In vivo precision errors were up to three-fold greater (Tt.BMD and Ct.Th) when variability in scan positioning was included. Inter-operator precision errors were significantly greater than short-term intra-operator precision (p<0.001). New trained operators achieved comparable intra-operator reproducibility to experienced operators, and lower inter-operator reproducibility (p<0.001). Precision errors were significantly greater for the radius than for the tibia. Conclusion Operator reference line positioning contributes significantly to in vivo measurement precision and is significantly greater for multi-operator datasets. Inter-operator variability can be significantly reduced using a systematic training platform, now available online (http://webapps.radiology.ucsf.edu/refline/). PMID:27475931

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.

Simultaneous determination of triacetin, acetic ether, butyl acetate and amorolfine hydrochloride in amorolfine liniment by HPLC.

PubMed

Gao, Yuan; Li, Li; Zhang, Jianjun; Shu, Wenjuan; Gao, Liqiong

2012-04-01

A simple, rapid, specific and precise reversed-phase high-performance liquid chromatographic method was developed for simultaneous estimation of triacetin, acetic ether, butyl acetate and amorolfine in marketed pharmaceutical liniment. Chromatographic separation was performed on a Shimadzu VP-ODS C(18) column using the mixture of citric acid-hydrochloric acid-sodium hydrate buffer (pH 3.0), acetonitrile and methanol (32:30:38) as the mobile phase at a flow rate of 1.0 mL/min with UV-detection at 215 nm. The method separated the four components simultaneously in less than 10 min. The validation of the method was performed with respect to specificity, linearity, accuracy, and precision. The calibration curves were linear in the range of 35.1-81.9 μ/mL for triacetin, 431.1-1005.9 μ/mL for acetic ether, 167.0-389.7 μ/mL for butyl acetate and 151.0-352.3 μ/mL for amorolfine. The mean 100% spiked recovery for triacetin, acetic ether, butyl acetate and amorolfine is 99.43 ± 0.42, 101.5 ± 1.09, 101.4 ± 1.02 and 100.8 ± 0.69, respectively. The intra-day and inter-day relative standard deviation values were <2.0%. The limits of detection of these compounds ranged from 0.08 to 5.88 ng. The utility of the procedure was verified by its application to the commercial liniment.

Development and validation of sensitive LC/MS/MS method for quantitative bioanalysis of levonorgestrel in rat plasma and application to pharmacokinetics study.

PubMed

Ananthula, Suryatheja; Janagam, Dileep R; Jamalapuram, Seshulatha; Johnson, James R; Mandrell, Timothy D; Lowe, Tao L

2015-10-15

Rapid, sensitive, selective and accurate LC/MS/MS method was developed for quantitative determination of levonorgestrel (LNG) in rat plasma and further validated for specificity, linearity, accuracy, precision, sensitivity, matrix effect, recovery efficiency and stability. Liquid-liquid extraction procedure using hexane:ethyl acetate mixture at 80:20 v:v ratio was employed to efficiently extract LNG from rat plasma. Reversed phase Luna column C18(2) (50×2.0mm i.d., 3μM) installed on a AB SCIEX Triple Quad™ 4500 LC/MS/MS system was used to perform chromatographic separation. LNG was identified within 2min with high specificity. Linear calibration curve was drawn within 0.5-50ng·mL(-1) concentration range. The developed method was validated for intra-day and inter-day accuracy and precision whose values fell in the acceptable limits. Matrix effect was found to be minimal. Recovery efficiency at three quality control (QC) concentrations 0.5 (low), 5 (medium) and 50 (high) ng·mL(-1) was found to be >90%. Stability of LNG at various stages of experiment including storage, extraction and analysis was evaluated using QC samples, and the results showed that LNG was stable at all the conditions. This validated method was successfully used to study the pharmacokinetics of LNG in rats after SubQ injection, providing its applicability in relevant preclinical studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Guided mass spectrum labelling in atom probe tomography.

PubMed

Haley, D; Choi, P; Raabe, D

2015-12-01

Atom probe tomography (APT) is a valuable near-atomic scale imaging technique, which yields mass spectrographic data. Experimental correctness can often pivot on the identification of peaks within a dataset, this is a manual process where subjectivity and errors can arise. The limitations of manual procedures complicate APT experiments for the operator and furthermore are a barrier to technique standardisation. In this work we explore the capabilities of computer-guided ranging to aid identification and analysis of mass spectra. We propose a fully robust algorithm for enumeration of the possible identities of detected peak positions, which assists labelling. Furthermore, a simple ranking scheme is developed to allow for evaluation of the likelihood of each possible identity being the likely assignment from the enumerated set. We demonstrate a simple, yet complete work-chain that allows for the conversion of mass-spectra to fully identified APT spectra, with the goal of minimising identification errors, and the inter-operator variance within APT experiments. This work chain is compared to current procedures via experimental trials with different APT operators, to determine the relative effectiveness and precision of the two approaches. It is found that there is little loss of precision (and occasionally gain) when participants are given computer assistance. We find that in either case, inter-operator precision for ranging varies between 0 and 2 "significant figures" (2σ confidence in the first n digits of the reported value) when reporting compositions. Intra-operator precision is weakly tested and found to vary between 1 and 3 significant figures, depending upon species composition levels. Finally it is suggested that inconsistencies in inter-operator peak labelling may be the largest source of scatter when reporting composition data in APT. Copyright © 2015 Elsevier B.V. All rights reserved.

Spectrofluorimetric determination of fluoroquinolones in pharmaceutical preparations.

PubMed

Ulu, Sevgi Tatar

2009-02-01

Simple, rapid and highly sensitive spectrofluorimetric method is presented for the determination of four fluoroquinolone (FQ) drugs, ciprofloxacin, enoxacin, norfloxacin and moxifloxacin in pharmaceutical preparations. Proposed method is based on the derivatization of FQ with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer of pH 9.0 to yield a yellow product. The optimum experimental conditions have been studied carefully. Beer's law is obeyed over the concentration range of 23.5-500 ng mL(-1) for ciprofloxacin, 28.5-700 ng mL(-1) for enoxacin, 29.5-800 ng mL(-1) for norfloxacin and 33.5-1000 ng mL(-1) for moxifloxacin using NBD-Cl reagent, respectively. The detection limits were found to be 7.0 ng mL(-1) for ciprofloxacin, 8.5 ng mL(-1) for enoxacin, 9.2 ng mL(-1) for norfloxacin and 9.98 ng mL(-1) for moxifloxacin, respectively. Intra-day and inter-day relative standard deviation and relative mean error values at three different concentrations were determined. The low relative standard deviation values indicate good precision and high recovery values indicate accuracy of the proposed methods. The method is highly sensitive and specific. The results obtained are in good agreement with those obtained by the official and reference method. The results presented in this report show that the applied spectrofluorimetric method is acceptable for the determination of the four FQ in the pharmaceutical preparations. Common excipients used as additives in pharmaceutical preparations do not interfere with the proposed method.

Application of 3-methylbenzothiazolin-2-one hydrazone for the quantitative spectrophotometric determination of oxcarbazepine in pharmaceuticals with cerium(IV) and periodate

NASA Astrophysics Data System (ADS)

Rajendraprasad, N.; Basavaiah, K.; Vinay, K. B.

2012-09-01

Two simple, sensitive, selective, accurate, and cost-effective spectrophotometric methods are described for the assay of oxcarbazepine (OXC) in bulk drug and in tablets. The methods are based on an oxidative coupling reaction involving OXC, 3-methylbenzothiazolin-2-one hydrazone (MBTH), and cerium(IV) sulfate at pH 4.28 ± 0.07 (method A) or sodium periodate at pH > 4.0 (method B) to form an orange colored product with an absorption maximum at 450 nm. Under optimized experimental conditions, the calibration graphs are linear over the ranges of 4-80 and 2-32 μg/ml for methods A and B, respectively, with correlation coefficient (r) values of 0.9984 and 0.9976. The apparent molar absorptivity values are 3.13ṡ103 and 9.13ṡ103 l/molṡcm for methods A and B, respectively. The other optical characteristics such as Sandell's sensitivity, limits of detection (LOD) and quantification (LOQ) values are also reported. The accuracy and precision of the methods were evaluated based on intra-day and inter-day variations. The proposed methods were successfully applied to the determination of OXC in tablets: the results were comparable with the published data obtained using the reference method. The reaction stoichiometry of OXC with MBTH (1:1 in method A and 1:2 in method B) was also evaluated using the limiting logarithmic method, and a possible reaction pathway is presented for the both methods.

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

PubMed

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

2011-11-01

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

Simultaneous determination of seven β-lactam antibiotics in human plasma for therapeutic drug monitoring and pharmacokinetic studies.

PubMed

Sime, Fekade Bruck; Roberts, Michael S; Roberts, Jason A; Robertson, Thomas A

2014-06-01

There is strong evidence in literature supporting the benefit of monitoring plasma concentrations of β-lactam antibiotics in the critically ill to ensure appropriateness of dosing. The objective of this work was to develop a method for the simultaneous determination of total concentrations piperacillin, benzylpenicillin, flucloxacillin, meropenem, ertapenem, cephazolin and ceftazidime in human plasma. Sample preparation involved protein precipitation with acetonitrile containing 0.1% formic acid and subsequent dilution of supernatant with 0.1% formic acid in water. Chromatographic separation was achieved on a reversed phase column (C18, 2.6 μm, 2.1 × 50 mm) via gradient elution using water and acetonitrile, each containing 0.1% formic acid, as mobile phase. Tandem mass spectrometry (MSMS) analysis was performed, after electrospray ionization in the positive mode, with multiple reaction monitoring (MRM). The method is accurate with the inter-day and intra-day accuracies of quality control samples (QCs) ranging from 95 to 107% and 95 to 108%, respectively. It is also precise with intra-day and inter-day coefficient of variations ranging from 4 to 12% and 5 to 14%, respectively. The lower limit of quantification was 0.1 μg/mL for each antibiotic except flucloxacillin (0.25 μg/mL). Recovery was greater than 96% for all analytes except for ertapenem (78%). Coefficients of variation for the matrix effect were less than 10% over the six batches of plasma. Analytes were stable over three freeze-thaw cycles, and for reasonable hours on the bench top as well as post-preparation. This novel liquid chromatography tandem mass spectrometry method proved accurate, precise and applicable for therapeutic drug monitoring and pharmacokinetic studies of the selected β-lactam antibiotics. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

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

PubMed

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

2017-10-25

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

Ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction for the simultaneous determination of 12 new antidepressants and 2 antipsychotics in whole blood by gas chromatography-mass spectrometry.

PubMed

Chen, Xiujuan; Zheng, Shuiqing; Le, Jian; Qian, Zheyuan; Zhang, Runsheng; Hong, Zhanying; Chai, Yifeng

2017-08-05

Antidepressant drugs are widely used in the treatment of different psychiatric disorders, as well as in conjunction with antipsychotics for the treatment of major depressive disorder. In this study, a simple and rapid ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) method was developed for the simultaneous determination of 12 new antidepressants (norfluoxetine, fluoxetine, fluvoxamine, agomelatine, mirtazapine, moclobemide, melitracen, N-desmethylmirtazapine, maprotiline, sertraline, citalopram, paroxetine) and 2 antipsychotics (clozapine and haloperidol) in human whole blood by gas chromatography-mass spectrometry (GC-MS). Different parameters affecting the UA-LDS-DLLME were optimized and the optimal conditions were as follows: 100μL of toluene as extraction solvent, extraction pH 12 and 3min of ultrasound stirring. Good linearity (R 2 ≥0.991) was obtained at the concentration range of 15-1500ng/mL for norfluoxetine, fluoxetine, fluvoxamine, melitracen, maprotiline and citalopram, and 5-500ng/mL for agomelatine, mirtazapine, moclobemide, N-desmethylmirtazapine, sertraline, paroxetine, clozapine and haloperidol. The intra-day and inter-day precision were all less than 10%, and accuracy of intra-day and inter-day were in the range of -12.7% to 7.9% and -13.9 to 11.8%, respectively. The extraction recoveries of most analytes were more than 60%. The UA-LDS-DLLME/GC-MS method was demonstrated with acceptable precision, accuracy and good specificity for the simultaneous determination of 12 antidepressants and 2 antipsychotics, and has been successfully applied in a real case. Copyright © 2017 Elsevier B.V. All rights reserved.

Cannabinoids assessment in plasma and urine by high performance liquid chromatography-tandem mass spectrometry after molecularly imprinted polymer microsolid-phase extraction.

PubMed

Sánchez-González, Juan; Salgueiro-Fernández, Rocío; Cabarcos, Pamela; Bermejo, Ana María; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

2017-02-01

A molecularly imprinted polymer (MIP) selective for cannabinoids [Δ 9 -tetrahydrocannabinol (Δ9-THC), 11-nor-9-carboxy-Δ 9 -tetrahydrocannabinol (Δ9-THC-COOH), and 11-hydroxy-Δ 9 -tetrahydrocannabinol (Δ9-THC-OH)] has been synthesized, fully characterized, and applied to the assessment of plasma and urine analysis of marijuana abuse by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Δ9-THC-COOH was used as a template molecule, whereas ethylene glycol dimethacrylate (EGDMA) was used as a functional monomer, divinylbenzene (DVB) as a cross-linker, and 2,2'-azobisisobutyronitrile (AIBN) as an initiator. The prepared MIP was found to be highly selective for cannabinoids typically found in blood and urine, and also for cannabinol (CBN) and cannabidiol (CBD). MIP beads (50 mg) were loaded inside a cone-shaped device made of a polypropylene (PP) membrane for microsolid-phase extraction (μ-SPE) in batch mode. Optimum retention of analytes (0.1 to 1.0 mL of plasma/urine) was achieved by fixing plasma/urine pH at 6.5 and assisting the procedure by mechanical shaking (150 rpm, 40 °C, 12 min). Optimum elution conditions implied 2 mL of a 90:10 methanol/acetic acid and ultrasound extraction (35 kHz, 325 W) for 6 min. Good precision was assessed by intra-day and inter-day assays. In addition, the method was found to be accurate after intra-day and inter-day analytical recovery assays and after analyzing control serum and urine control samples. The limits of quantification were in the range of 0.36-0.49 ng L -1 (plasma analysis) and 0.47-0.57 ng L -1 (urine analysis). These values are low enough for confirmative conclusions regarding marijuana abuse through blood and urine analysis. Graphical Abstract ᅟ.

Determination of 13C isotopic enrichment of valine and threonine by GC-C-IRMS after formation of the N(O,S)-ethoxycarbonyl ethyl ester derivatives of the amino acids.

PubMed

Godin, Jean-Philippe; Faure, Magali; Breuille, Denis; Hopfgartner, Gérard; Fay, Laurent-Bernard

2007-06-01

We describe a new method of assessing, in a single run, (13)C isotopic enrichment of both Val and Thr by gas chromatography-combustion-isotope-ratio mass spectrometry (GC-C-IRMS). This method characterised by a rapid one-step derivatisation procedure performed at room temperature to form the N(O,S)-ethoxycarbonyl ethyl ester derivatives, and a polar column for GC. The suitability of this method for Val and Thr in in-vivo samples (mucosal hydrolysate) was demonstrated by studying protein metabolism with two tracers ((13)C-valine or (13)C-threonine). The intra-day and inter-day repeatability were both assessed either with standards or with in-vivo samples at natural abundance and at low (13)C isotopic enrichment. For inter-day repeatability CVs were between 0.8 and 1.5% at natural abundance and lower than 5.5% at 0.112 and 0.190 atom% enrichment for Val and Thr, respectively. Overall isotopic precision was studied for eleven standard amino acid derivatives (those of Val, Ala, Leu, Iso, Gly, Pro, Asp, Thr, Ser, Met, and Phe) and was assessed at 0.32 per thousand. The (13)C isotopic measurement was then extended to the other amino acids (Ala, Val, Leu, Iso, Gly, Pro, Thr, and Phe) at natural abundance for in-vivo samples. The isotopic precision was better than 0.002 atom% per amino acid (for n = 4 rats). This analytical method was finally applied to an animal study to measure Thr utilization in protein synthesis.

Analysis of tacrolimus and creatinine from a single dried blood spot using liquid chromatography tandem mass spectrometry.

PubMed

Koop, Dennis R; Bleyle, Lisa A; Munar, Myrna; Cherala, Ganesh; Al-Uzri, Amira

2013-05-01

Long term therapeutic drug monitoring and assessment of renal function are required in renal transplant recipients on immunosuppressant therapy such as tacrolimus. Dry blood spots (DBS) have been used successfully in the clinic for many years and offers a convenient, simple and non-invasive method for repeated blood tests. We developed and performed a preliminary validation of a method for the analysis of tacrolimus and creatinine from a single DBS using liquid chromatography-tandem mass spectrometric (LC-MS/MS). Tacrolimus and creatinine were extracted from a 6mm punch with a mixture of methanol/acetonitrile containing ascomycin and deuterated creatinine as internal standards. A 10 μl aliquot of the extract was analyzed directly after dilution for creatinine with normal phase high performance liquid chromatography and multiple reaction monitoring. The remainder of the extract was processed and analyzed for tacrolimus. The lower limit of quantification for tacrolimus was 1 ng/ml with accuracy of 0.34% bias and precision (CV) of 11.1%. The precision ranged from 1.33% to 7.68% and accuracy from -4.44% to 11.6% bias for the intra- and inter-day analysis. The lower limit of quantification of creatinine was 0.01 mg/dL with precision of 7.94%. Accuracy was based on recovery of additional creatinine spiked into whole blood samples and ranged from -2.45% bias at 5 mg/dL to 3.75% bias at 0.5 mg/dL. Intra- and inter-day precision was from 3.48 to 4.11%. The assay was further validated with DBS prepared from pediatric renal transplant recipients. There was excellent correlation between the levels of tacrolimus and creatinine obtained from the clinical laboratory and the DBS method developed. After additional validation, this assay may have a significant impact on compliance with medication intake as well as potentially lowering the cost associated with intravenous blood draws in clinical laboratories. Copyright © 2013 Elsevier B.V. All rights reserved.

Inter-rater reliability of a modified version of Delitto et al.’s classification-based system for low back pain: a pilot study

PubMed Central

Apeldoorn, Adri T.; van Helvoirt, Hans; Ostelo, Raymond W.; Meihuizen, Hanneke; Kamper, Steven J.; van Tulder, Maurits W.; de Vet, Henrica C. W.

2016-01-01

Study design Observational inter-rater reliability study. Objectives To examine: (1) the inter-rater reliability of a modified version of Delitto et al.’s classification-based algorithm for patients with low back pain; (2) the influence of different levels of familiarity with the system; and (3) the inter-rater reliability of algorithm decisions in patients who clearly fit into a subgroup (clear classifications) and those who do not (unclear classifications). Methods Patients were examined twice on the same day by two of three participating physical therapists with different levels of familiarity with the system. Patients were classified into one of four classification groups. Raters were blind to the others’ classification decision. In order to quantify the inter-rater reliability, percentages of agreement and Cohen’s Kappa were calculated. Results A total of 36 patients were included (clear classification n = 23; unclear classification n = 13). The overall rate of agreement was 53% and the Kappa value was 0·34 [95% confidence interval (CI): 0·11–0·57], which indicated only fair inter-rater reliability. Inter-rater reliability for patients with a clear classification (agreement 52%, Kappa value 0·29) was not higher than for patients with an unclear classification (agreement 54%, Kappa value 0·33). Familiarity with the system (i.e. trained with written instructions and previous research experience with the algorithm) did not improve the inter-rater reliability. Conclusion Our pilot study challenges the inter-rater reliability of the classification procedure in clinical practice. Therefore, more knowledge is needed about factors that affect the inter-rater reliability, in order to improve the clinical applicability of the classification scheme. PMID:27559279

Development and validation of a new method to simultaneously quantify triazoles in plasma spotted on dry sample spot devices and analysed by HPLC-MS.

PubMed

Baietto, Lorena; D'Avolio, Antonio; Marra, Cristina; Simiele, Marco; Cusato, Jessica; Pace, Simone; Ariaudo, Alessandra; De Rosa, Francesco Giuseppe; Di Perri, Giovanni

2012-11-01

Therapeutic drug monitoring (TDM) of triazoles is widely used in clinical practice to optimize therapy. TDM is limited by technical problems and cost considerations, such as sample storage and dry-ice shipping. We aimed to develop and validate a new method to analyse itraconazole, posaconazole and voriconazole in plasma spotted on dry sample spot devices (DSSDs) and to quantify them by an HPLC system. Extraction from DSSDs was done using n-hexane/ethyl acetate and ammonia solution. Samples were analysed using HPLC with mass spectrometry (HPLC-MS). Accuracy and precision were assayed by inter- and intra-day validation. The stability of triazoles in plasma spotted on DSSDs was investigated at room temperature for 1 month. The method was compared with a validated standard HPLC method for quantification of triazoles in human plasma. Mean inter- and intra-day accuracy and precision were <15% for all compounds. Triazoles were stable for 2 weeks at room temperature. The method was linear (r(2) > 0.999) in the range 0.031-8 mg/L for itraconazole and posaconazole, and 0.058-15 mg/L for voriconazole. High sensitivity was observed; limits of detection were 0.008, 0.004 and 0.007 mg/L for itraconazole, posaconazole and voriconazole, respectively. A high degree of correlation (r(2) > 0.94) was obtained between the DSSD method and the standard method of analysis. The method that we developed and validated to quantify triazoles in human plasma spotted on DSSDs is accurate and precise. It overcomes problems related to plasma sample storage and shipment, allowing TDM to be performed in a cheaper and safer manner.

Development and validation of a rapid reversed-phase HPLC method for the determination of the non-nucleoside reverse transcriptase inhibitor dapivirine from polymeric nanoparticles.

PubMed

das Neves, José; Sarmento, Bruno; Amiji, Mansoor M; Bahia, Maria Fernanda

2010-06-05

The objective of this work was to develop and validate a rapid reversed-phase (RP) high-performance liquid chromatography (HPLC) method for the in vitro pharmaceutical characterization of dapivirine-loaded polymeric nanoparticles. Chromatographic runs were performed on a RP C18 column with a mobile phase comprising acetonitrile-0.5% (w/v) triethanolamine solution in isocratic mode (80:20, v/v) at a flow rate of 1 ml/min. Dapivirine was detected at a wavelength of 290 nm. The method was shown to be specific, linear in the range of 1-50 microg/ml (R(2)=0.9998), precise at the intra-day and inter-day levels as reflected by the relative standard deviation values (less than 0.85%), accurate (recovery rate of 100.17+/-0.35%), and robust to changes in the mobile phase and column brand. The detection and quantitation limits were 0.08 and 0.24 microg/ml, respectively. The method was successfully used to determine the loading capacity and association efficiency of dapivirine in poly(lactic-co-glycolic acid)-based nanoparticles and its in vitro release. Copyright (c) 2010 Elsevier B.V. All rights reserved.

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

PubMed

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

2017-01-01

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

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.

Characteristics of seasonal variation and solar activity dependence of the geomagnetic solar quiet daily variation

NASA Astrophysics Data System (ADS)

Shinbori, A.; Koyama, Y.; Nose, M.; Hori, T.

2017-12-01

Characteristics of seasonal variation and solar activity dependence of the X- and Y-components of the geomagnetic solar quiet (Sq) daily variation at Memanbetsu in mid-latitudes and Guam near the equator have been investigated using long-term geomagnetic field data with 1-h time resolution from 1957 to 2016. In this analysis, we defined the quiet day when the maximum value of the Kp index is less than 3 for that day. In this analysis, we used the monthly average of the adjusted daily F10.7 corresponding to geomagnetically quiet days. For identification of the monthly mean Sq variation in the X and Y components (Sq-X and Sq-Y), we first determined the baseline of the X and Y components from the average value from 22 to 2 h (LT: local time) for each quiet day. Next, we calculated a deviation from the baseline of the X- and Y-components of the geomagnetic field for each quiet day, and computed the monthly mean value of the deviation for each local time. As a result, Sq-X and Sq-Y shows a clear seasonal variation and solar activity dependence. The amplitude of seasonal variation increases significantly during high solar activities, and is proportional to the solar F10.7 index. The pattern of the seasonal variation is quite different between Sq-X and Sq-Y. The result of the correlation analysis between the solar F10.7 index and Sq-X and Sq-Y shows almost the linear relationship, but the slope and intercept of the linear fitted line varies as function of local time and month. This implies that the sensitivity of Sq-X and Sq-Y to the solar activity is different for different local times and seasons. The local time dependence of the offset value of Sq-Y at Guam and its seasonal variation suggest a magnetic field produced by inter-hemispheric field-aligned currents (FACs). From the sign of the offset value of Sq-Y, it is infer that the inter-hemispheric FACs flow from the summer to winter hemispheres in the dawn and dusk sectors and from the winter to summer hemispheres in the pre-noon to afternoon sectors. From the slope of the linear fitted line, we observe a weak solar activity dependence of the inter-hemispheric FACs, which shows that the intensity of inter-hemispheric FACs has positive and negative correlations in the morning-noon and afternoon sectors, respectively.

Ultrasound-assisted combined with nano-sized molecularly imprinted polymer for selective extraction and pre-concentration of amitriptyline in human plasma with gas chromatography-flame detection.

PubMed

Khanahmadzadeh, Salah; Tarigh, Ahmad

2014-12-01

A new process was developed for the selective extraction and pre-concentration of amitriptyline (AT) from human plasma using nano-sized molecularly imprinted polymer (MIP) with ultrasound-assisted extraction (UAE). The nano-sized AT imprinted polymer particles were synthesized using suspension polymerization in silicon oil and characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscope (SEM) methods. With the application of optimized values, linearity values in the ranges of 20-200μgmL(-1) and 35-200μgmL(-1) were obtained for AT with the correlation of determination values (r(2)) 0.998 and 0.995 in water and plasma, respectively. The limits of detections (S/N=3) for AT were found to be 0.7 and 1.2μgmL(-1) in water and plasma, respectively. The enrichment factors of AT in water and plasma were 52 and 40, respectively. The inter-day precisions (%) were in the range of 5.8-9.2%. Relative recovery rates ranged from 82.4% to 92.3%. The method was successfully applied to determine AT in the human plasma samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Sonographic estimation of fetal weight: comparison of bias, precision and consistency using 12 different formulae.

PubMed

Anderson, N G; Jolley, I J; Wells, J E

2007-08-01

To determine the major sources of error in ultrasonographic assessment of fetal weight and whether they have changed over the last decade. We performed a prospective observational study in 1991 and again in 2000 of a mixed-risk pregnancy population, estimating fetal weight within 7 days of delivery. In 1991, the Rose and McCallum formula was used for 72 deliveries. Inter- and intraobserver agreement was assessed within this group. Bland-Altman measures of agreement from log data were calculated as ratios. We repeated the study in 2000 in 208 consecutive deliveries, comparing predicted and actual weights for 12 published equations using Bland-Altman and percentage error methods. We compared bias (mean percentage error), precision (SD percentage error), and their consistency across the weight ranges. 95% limits of agreement ranged from - 4.4% to + 3.3% for inter- and intraobserver estimates, but were - 18.0% to 24.0% for estimated and actual birth weight. There was no improvement in accuracy between 1991 and 2000. In 2000 only six of the 12 published formulae had overall bias within 7% and precision within 15%. There was greater bias and poorer precision in nearly all equations if the birth weight was < 1,000 g. Observer error is a relatively minor component of the error in estimating fetal weight; error due to the equation is a larger source of error. Improvements in ultrasound technology have not improved the accuracy of estimating fetal weight. Comparison of methods of estimating fetal weight requires statistical methods that can separate out bias, precision and consistency. Estimating fetal weight in the very low birth weight infant is subject to much greater error than it is in larger babies. Copyright (c) 2007 ISUOG. Published by John Wiley & Sons, Ltd.

Methods for the Precise Locating and Forming of Arrays of Curved Features into a Workpiece

DOEpatents

Gill, David Dennis; Keeler, Gordon A.; Serkland, Darwin K.; Mukherjee, Sayan D.

2008-10-14

Methods for manufacturing high precision arrays of curved features (e.g. lenses) in the surface of a workpiece are described utilizing orthogonal sets of inter-fitting locating grooves to mate a workpiece to a workpiece holder mounted to the spindle face of a rotating machine tool. The matching inter-fitting groove sets in the workpiece and the chuck allow precisely and non-kinematically indexing the workpiece to locations defined in two orthogonal directions perpendicular to the turning axis of the machine tool. At each location on the workpiece a curved feature can then be on-center machined to create arrays of curved features on the workpiece. The averaging effect of the corresponding sets of inter-fitting grooves provide for precise repeatability in determining, the relative locations of the centers of each of the curved features in an array of curved features.

Response time distributions in rapid chess: a large-scale decision making experiment.

PubMed

Sigman, Mariano; Etchemendy, Pablo; Slezak, Diego Fernández; Cecchi, Guillermo A

2010-01-01

Rapid chess provides an unparalleled laboratory to understand decision making in a natural environment. In a chess game, players choose consecutively around 40 moves in a finite time budget. The goodness of each choice can be determined quantitatively since current chess algorithms estimate precisely the value of a position. Web-based chess produces vast amounts of data, millions of decisions per day, incommensurable with traditional psychological experiments. We generated a database of response times (RTs) and position value in rapid chess games. We measured robust emergent statistical observables: (1) RT distributions are long-tailed and show qualitatively distinct forms at different stages of the game, (2) RT of successive moves are highly correlated both for intra- and inter-player moves. These findings have theoretical implications since they deny two basic assumptions of sequential decision making algorithms: RTs are not stationary and can not be generated by a state-function. Our results also have practical implications. First, we characterized the capacity of blunders and score fluctuations to predict a player strength, which is yet an open problem in chess softwares. Second, we show that the winning likelihood can be reliably estimated from a weighted combination of remaining times and position evaluation.

Response Time Distributions in Rapid Chess: A Large-Scale Decision Making Experiment

PubMed Central

Sigman, Mariano; Etchemendy, Pablo; Slezak, Diego Fernández; Cecchi, Guillermo A.

2010-01-01

Rapid chess provides an unparalleled laboratory to understand decision making in a natural environment. In a chess game, players choose consecutively around 40 moves in a finite time budget. The goodness of each choice can be determined quantitatively since current chess algorithms estimate precisely the value of a position. Web-based chess produces vast amounts of data, millions of decisions per day, incommensurable with traditional psychological experiments. We generated a database of response times (RTs) and position value in rapid chess games. We measured robust emergent statistical observables: (1) RT distributions are long-tailed and show qualitatively distinct forms at different stages of the game, (2) RT of successive moves are highly correlated both for intra- and inter-player moves. These findings have theoretical implications since they deny two basic assumptions of sequential decision making algorithms: RTs are not stationary and can not be generated by a state-function. Our results also have practical implications. First, we characterized the capacity of blunders and score fluctuations to predict a player strength, which is yet an open problem in chess softwares. Second, we show that the winning likelihood can be reliably estimated from a weighted combination of remaining times and position evaluation. PMID:21031032

Validation of a QuEChERS-based gas chromatographic method for analysis of pesticide residues in Cassia angustifolia (senna).

PubMed

Tripathy, Vandana; Saha, Ajoy; Patel, Dilipkumar J; Basak, B B; Shah, Paresh G; Kumar, Jitendra

2016-08-02

A simple multi-residue method based on modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach was established for the determination of 17 organochlorine (OC), 15 organophosphorous (OP) and 7 synthetic pyrethroid (SP) pesticides in an economically important medicinal plant of India, Senna (Cassia angustifolia), by gas chromatography coupled to electron capture and flame thermionic detectors (GC/ECD/FTD) and confirmation of residues was done on gas chromatograph coupled with mass spectrometry (GC-MS). The developed method was validated by testing the following parameters: linearity, limit of detection (LOD), limit of quantification (LOQ), matrix effect, accuracy-precision and measurement uncertainty; the validation study clearly demonstrated the suitability of the method for its intended application. All pesticides showed good linearity in the range 0.01-1.0 μg mL(-1) for OCs and OPs and 0.05-2.5 μg mL(-1) for SPs with correlation coefficients higher than 0.98. The method gave good recoveries for most of the pesticides (70-120%) with intra-day and inter-day precision < 20% in most of the cases. The limits of detection varied from 0.003 to 0.03 mg kg(-1), and the LOQs were determined as 0.01-0.049 mg kg(-1). The expanded uncertainties were <30%, which was distinctively less than a maximum default value of ±50%. The proposed method was successfully applied to determine pesticide residues in 12 commercial market samples obtained from different locations in India.

Simultaneous determination of amphetamine-type stimulants and cannabinoids in fingernails by gas chromatography-mass spectrometry.

PubMed

Kim, Jin Young; Cheong, Jae Chul; Kim, Min Kyoung; Lee, Jae Il; In, Moon Kyo

2008-06-01

A gas chromatography-mass spectrometric (GC-MS) method was developed and validated for the simultaneous detection and quantification of four amphetamine-type stimulants (amphetamine (AP), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA)) and two cannabinoids (Delta9-tetrahydrocannabinol (Delta9-THC) and 11-nor-Delta9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH)) in fingernails. Fingernail clippings (30 mg) were washed with distilled water and methanol, and then incubated in 1.0 M sodium hydroxide at 95 degrees C for 30 min. The compounds of interest were isolated by liquid-liquid extraction followed by derivatization with N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA) at 70 degrees C for 15 min. The derivatized compounds were analyzed by GC-MS in the selective ion monitoring (SIM) mode. The linear ranges were 0.1-15.0 ng/mg for AP, 0.2-15.0 ng/mg for MDA, Delta9-THC and THCCOOH, and 0.2-30.0 ng/mg for MA and MDMA, with good correlation coefficients (r2 > 0.9991). The intra-day, inter-day, and inter-person precisions were within 10.6%, 6.3%, and 5.3%, respectively. The intra-day, inter-day and inter-person accuracies were between -6.1 and 5.0%, -6.2 and 5.7%, and -6.4 and 5.6%, respectively. The limits of detection (LODs) and quantification (LOQs) for each compound were lower than 0.056 and 0.2 ng/mg, respectively. The recoveries were in the range of 74.0-94.8%. Positive GC-MS results were obtained from specimens of nine suspected MA or cannabis abusers. The concentration ranges of MA, AP, and THCCOOH were 0.10-1.41, 0.12-2.64, and 0.20 ng/mg, respectively. Based on these results, the method proved to be effective for the simultaneous qualification and quantification of amphetamine-type stimulants and cannabinoids in fingernails.

Rapid method for the determination of 14 isoflavones in food using UHPLC coupled to photo diode array detection.

PubMed

Shim, You-Shin; Yoon, Won-Jin; Hwang, Jin-Bong; Park, Hyun-Jin; Seo, Dongwon; Ha, Jaeho

2015-11-15

A rapid method for the determination of 14 types of isoflavones in food using ultra-high performance liquid chromatography (UHPLC) was validated in terms of precision, accuracy, sensitivity and linearity. The UHPLC separation was performed on a reverse-phase C18 column (particle size 2 μm, i.d. 2 mm, length 100 mm) using a photo diode array detector that was fixed to 260 nm. The limits of detection and quantification of the UHPLC analyses ranged from 0.03 to 0.33 mg kg(-1). The intra-day and inter-day precision of the individual isoflavones were less than 11.77% and calibration curves exhibited good linearity (r(2) = 0.99) within the tested ranges. These results suggest that the rapid method used in this study could be available to determine of 14 types of isoflavones in a variety of food such as soy bean, black bean, red bean and soybean paste. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

Determining inter-system bias of GNSS signals with narrowly spaced frequencies for GNSS positioning

NASA Astrophysics Data System (ADS)

Tian, Yumiao; Liu, Zhizhao; Ge, Maorong; Neitzel, Frank

2017-12-01

Relative positioning using multi-GNSS (global navigation satellite systems) can improve accuracy, reliability, and availability compared to the use of a single constellation system. Intra-system double-difference (DD) ambiguities (ISDDAs) refer to the DD ambiguities between satellites of a single constellation system and can be fixed to an integer to derive the precise fixed solution. Inter-system ambiguities, which denote the DD ambiguities between different constellation systems, can also be fixed to integers on overlapping frequencies, once the inter-system bias (ISB) is removed. Compared with fixing ISDDAs, fixing both integer intra- and inter-system DD ambiguities (IIDDAs) means an increase of positioning precision through an integration of multiple GNSS constellations. Previously, researchers have studied IIDDA fixing with systems of the same frequencies, but not with systems of different frequencies. Integer IIDDAs can be determined from single-difference (SD) ambiguities, even if the frequencies of multi-GNSS signals used in the positioning are different. In this study, we investigated IIDDA fixing for multi-GNSS signals of narrowly spaced frequencies. First, the inter-system DD models of multi-GNSS signals of different frequencies are introduced, and the strategy for compensating for ISB is presented. The ISB is decomposed into three parts: 1) a float approximate ISB number that can be considered equal to the ISB of code pseudorange observations and thus can be estimated through single point positioning (SPP); 2) a number that is a multiple of the GNSS signal wavelength; and 3) a fractional ISB part, with a magnitude smaller than a single wavelength. Then, the relationship between intra- and inter-system DD ambiguity RATIO values and ISB was investigated by integrating GPS L1 and GLONASS L1 signals. In our numerical analyses with short baselines, the ISB parameter and IIDDA were successfully fixed, even if the number of observed satellites in each system was small.

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

PubMed

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

2013-07-30

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

An ultraviolet-spectrophotometric method for the determination of glimepiride in solid dosage forms.

PubMed

Afieroho, Ozadheoghene E; Okorie, Ogbonna; Okonkwo, Tochukwu J N

2011-06-01

Considering the cost of acquiring a liquid chromatographic instrument in underdeveloped economies, the rising incidence of diabetes mellitus, the need to evaluate the quality performance of glimepiride generics, and the need for less toxic processes, this research is an imperative. The method was validated for linearity, recovery accuracy, intra- and inter-day precision, specificity in the presence of excipients, and inter-day stability under laboratory conditions. Student's t test at the 95% confidence limit was used for statistics. Using 96% ethanol as solvent, a less toxic and cost-effective spectrophotometric method for the determination of glimepiride in solid dosage forms was developed and validated. The results of the validated parameters showed a λ(max) of 231 nm, linearity range of 0.5-22 μg/mL, precision with relative SD of <1.0%, recovery accuracy of 100.8%, regression equation of y = 45.741x + 0.0202, R(2) = 0.999, limit of detection of 0.35 μg/mL, and negligible interference from common excipients and colorants. The method was found to be accurate at the 95% confidence limit compared with the standard liquid chromatographic method with comparable reproducibility when used to assay the formulated products Amaryl(®) (sanofi-aventis, Paris, France) and Mepyril(®) (May & Baker Nigeria PLC, Ikeja, Nigeria). The results obtained for the validated parameters were within allowable limits. This method is recommended for routine quality control analysis.

Development and validation of a rapid reverse-phase HPLC method for the determination of methotrexate from nanostructured liquid crystalline systems.

PubMed

Zuben, E S Von; Oliveira, A G; Chorilli, M; Scarpa, M V

2018-03-05

A reversed-phase liquid chromatography (RP-LC) method was successfully developed and validated for the determination of methotrexate in nanostructured liquid crystalline systems composed by polyether functional siloxane and silicone polyether copolymer. The LC method was performed on RP C18-ODS column, Agilent Zorbax® (4.6 x 250 mm, 5 μm), maintained at room temperature, with a mobile phase constituted by a mixture of 50 mM ammonium acetate buffer (pH 6.0) and methanol (77:23,v/v) with a flow rate of 1.0 mL/min, using ultraviolet detection at 313 nm. The parameters used in the validation process were linearity, specificity, intra and inter-day precision, accuracy, robustness. The quantitation and detection limits yielded good results. The calibration plot assumed linear behavior from 5.0-150.0 μg. mL-1 (r2 = 0.9999). The methotrexate was subjected to oxidation, acid, base and neutral degradation, photolysis and heat as stress conditions. There were no interfering peaks at or near the retention time of methotrexate. The nanostructured liquid crystalline systems did not interfere with the analysis and the recovery was quantitative. The intra and inter-day assay relative standard deviation were less than 0.20 %. The method developed proved to be simple, sensitive, accurate, precise, reproducible and therefore adequate for routine analysis of methotrexate in nanostructured liquid crystalline systems.

A validated solid-phase extraction HPLC method for the simultaneous determination of the citrus flavanone aglycones hesperetin and naringenin in urine.

PubMed

Kanaze, Feras Imad; Kokkalou, Eugene; Georgarakis, Manolis; Niopas, Ioannis

2004-09-21

A simple, specific, precise, accurate, and robust HPLC assay for the simultaneous analysis of hesperetin and naringenin in human urine was developed and validated. Urine samples were incubated with beta-glucuronidase/sulphatase and the analytes were isolated by solid-phase extraction using C18 cartridges and separated on a C8 reversed phase column using a mixture of methanol/water/acetic acid (40:58:2, v/v/v) at 45 degrees C. The method was found to be linear in the 50-1200 ng/ml concentration range for both hesperetin and naringenin (r > 0.999). The accuracy of the method was greater than 94.8%, while the intra- and inter-day precision for hesperetin was better than 4.9 and 8.2%, respectively and for naringenin was better than 5.3 and 7.8%, respectively. Recovery for hesperetin, naringenin and internal standard 7-ethoxycoumarin was greater than 70.9%. The method has been applied for the determination of hesperetin and naringenin in urine samples obtained from a male volunteer following a single 300 mg oral dose of each of the corresponding flavanone glycosides hesperidin and naringin. The intra- and inter-day reproducibility through enzyme hydrolysis was less than 3.9% for both total (free + conjugated) hesperetin and naringenin. Stability studies showed urine quality control samples to be stable for both hesperetin and naringenin through three freeze-thaw cycles and at room temperature for 24 h (error < or = 3.6%).

Intra-/inter-laboratory validation study on reactive oxygen species assay for chemical photosafety evaluation using two different solar simulators.

PubMed

Onoue, Satomi; Hosoi, Kazuhiro; Toda, Tsuguto; Takagi, Hironori; Osaki, Naoto; Matsumoto, Yasuhiro; Kawakami, Satoru; Wakuri, Shinobu; Iwase, Yumiko; Yamamoto, Toshinobu; Nakamura, Kazuichi; Ohno, Yasuo; Kojima, Hajime

2014-06-01

A previous multi-center validation study demonstrated high transferability and reliability of reactive oxygen species (ROS) assay for photosafety evaluation. The present validation study was undertaken to verify further the applicability of different solar simulators and assay performance. In 7 participating laboratories, 2 standards and 42 coded chemicals, including 23 phototoxins and 19 non-phototoxic drugs/chemicals, were assessed by the ROS assay using two different solar simulators (Atlas Suntest CPS series, 3 labs; and Seric SXL-2500V2, 4 labs). Irradiation conditions could be optimized using quinine and sulisobenzone as positive and negative standards to offer consistent assay outcomes. In both solar simulators, the intra- and inter-day precisions (coefficient of variation; CV) for quinine were found to be below 10%. The inter-laboratory CV for quinine averaged 15.4% (Atlas Suntest CPS) and 13.2% (Seric SXL-2500V2) for singlet oxygen and 17.0% (Atlas Suntest CPS) and 7.1% (Seric SXL-2500V2) for superoxide, suggesting high inter-laboratory reproducibility even though different solar simulators were employed for the ROS assay. In the ROS assay on 42 coded chemicals, some chemicals (ca. 19-29%) were unevaluable because of limited solubility and spectral interference. Although several false positives appeared with positive predictivity of ca. 76-92% (Atlas Suntest CPS) and ca. 75-84% (Seric SXL-2500V2), there were no false negative predictions in both solar simulators. A multi-center validation study on the ROS assay demonstrated satisfactory transferability, accuracy, precision, and predictivity, as well as the availability of other solar simulators. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

Gong, G; Liu, C; Liu, C

Purpose: To analyze the error in contouring the brainstem for patients with head and neck cancer who underwent radiotherapy based on computed tomography (CT) and magnetic resonance (MR) images. Methods: 20 brain tumor and 17 nasopharyngeal cancer patients were randomly selected. Each patient underwent MR and CT scanning. For each patient, one observer contoured the brainstem on CT and MR images for 10 times, and 10 observers from five centers delineated the brainstem on CT and MR images only one time. The inter- and intra-observers volume and outline variations were compared. Results: The volumes of brainstem contoured by inter- andmore » intra-observers on CT and MR images were similar (p>0.05). The reproducibility of contouring brainstem on MR images was better than that on CT images (p<0.05) for both inter- and intra-observer variability. The inter- and intra-observer for contouring on CT images reached mean values of 0.81±0.05 (p>0.05) and of 0.85±0.05 (p>0.05), respectively, while on MR images these respective values were 0.90±0.05 (p>0.05) and 0.92±0.04 (p>0.05). Conclusion: Contouring the brainstem on MR images was more accurate and reproducible than that on CT images. Precise information might be more helpful for protecting the brainstem radiation injury the patients whose lesion were closed to brainstem.« less

Repeatability, variability and reference values of pulsed wave Doppler echocardiographic measurements in healthy Saanen goats

PubMed Central

2012-01-01

Background Pulsed wave (PW) Doppler echocardiography has become a routine non invasive cardiac diagnostic tool in most species. However, evaluation of intracardiac blood flow requires reference values, which are poorly documented in goats. The aim of this study was to test the repeatability, the variability, and to establish the reference values of PW measurements in healthy adult Saanen goats. Using a standardised PW Doppler echocardiographic protocol, 10 healthy adult unsedated female Saanen goats were investigated three times at one day intervals by the same observer. Mitral, tricuspid, aortic and pulmonary flows were measured from a right parasternal view, and mitral and aortic flows were also measured from a left parasternal view. The difference between left and right side measurements and the intra-observer inter-day repeatability were tested and then the reference values of PW Doppler echocardiographic parameters in healthy adult female Saanen goats were established. Results As documented in other species, all caprine PW Doppler parameters demonstrated a poor inter-day repeatability and a moderate variability. Tricuspid and pulmonary flows were best evaluated on the right side whereas mitral and aortic flows were best obtained on the left side, and reference values are reported for healthy adult Saanen goats. Conclusions PW Doppler echocardiography allows the measurement of intracardiac blood flow indices in goats. The reference values establishment will help interpreting these indices of cardiac function in clinical cardiac cases and developing animal models for human cardiology research. PMID:23067875

Precision measurement of the electromagnetic dipole strengths in Be11

NASA Astrophysics Data System (ADS)

Kwan, E.; Wu, C. Y.; Summers, N. C.; Hackman, G.; Drake, T. E.; Andreoiu, C.; Ashley, R.; Ball, G. C.; Bender, P. C.; Boston, A. J.; Boston, H. C.; Chester, A.; Close, A.; Cline, D.; Cross, D. S.; Dunlop, R.; Finlay, A.; Garnsworthy, A. B.; Hayes, A. B.; Laffoley, A. T.; Nano, T.; Navrátil, P.; Pearson, C. J.; Pore, J.; Quaglioni, S.; Svensson, C. E.; Starosta, K.; Thompson, I. J.; Voss, P.; Williams, S. J.; Wang, Z. M.

2014-05-01

The electromagnetic dipole strength in Be11 between the bound states has been measured using low-energy projectile Coulomb excitation at bombarding energies of 1.73 and 2.09 MeV/nucleon on a Pt196 target. An electric dipole transition probability B(E1;1/2-→1/2+)=0.102(2) e2fm was determined using the semi-classical code Gosia, and a value of 0.098(4) e2fm was determined using the Extended Continuum Discretized Coupled Channels method with the quantum mechanical code FRESCO. These extracted B(E1) values are consistent with the average value determined by a model-dependent analysis of intermediate energy Coulomb excitation measurements and are approximately 14% lower than that determined by a lifetime measurement. The much-improved precisions of 2% and 4% in the measured B(E1) values between the bound states deduced using Gosia and the Extended Continuum Discretized Coupled Channels method, respectively, compared to the previous accuracy of ˜10% will help in our understanding of and better improve the realistic inter-nucleon interactions.

Flow-batch analysis of clenbuterol based on analyte extraction on molecularly imprinted polymers coupled to an in-system chromogenic reaction. Application to human urine and milk substitute samples.

PubMed

González, Natalia; Grünhut, Marcos; Šrámková, Ivana; Lista, Adriana G; Horstkotte, Burkhard; Solich, Petr; Sklenářová, Hana; Acebal, Carolina C

2018-02-01

A fully automated spectrophotometric method based on flow-batch analysis has been developed for the determination of clenbuterol including an on-line solid phase extraction using a molecularly imprinted polymer (MIP) as the sorbent. The molecularly imprinted solid phase extraction (MISPE) procedure allowed analyte extraction from complex matrices at low concentration levels and with high selectivity towards the analyte. The MISPE procedure was performed using a commercial MIP cartridge that was introduced into a guard column holder and integrated in the analyzer system. Optimized parameters included the volume of the sample, the type and volume of the conditioning and washing solutions, and the type and volume of the eluent. Quantification of clenbuterol was carried out by spectrophotometry after in-system post-elution analyte derivatization based on azo-coupling using N- (1-Naphthyl) ethylenediamine as the coupling agent to yield a red-colored compound with maximum absorbance at 500nm. Both the chromogenic reaction and spectrophotometric detection were performed in a lab-made flow-batch mixing chamber that replaced the cuvette holder of the spectrophotometer. The calibration curve was linear in the 0.075-0.500mgL -1 range with a correlation coefficient of 0.998. The precision of the proposed method was evaluated in terms of the relative standard deviation obtaining 1.1% and 3.0% for intra-day precision and inter-day precision, respectively. The detection limit was 0.021mgL -1 and the sample throughput for the entire process was 3.4h -1 . The proposed method was applied for the determination of CLB in human urine and milk substitute samples obtaining recoveries values within a range of 94.0-100.0%. Copyright © 2017 Elsevier B.V. All rights reserved.

A method for fast determination of psoralens in oral solutions of phytomedicines using liquid chromatography.

PubMed

Pires, Adriana Elias; Honda, Neli Kiko; Cardoso, Cláudia Andréa Lima

2004-10-29

A method for sample preparation and analysis by high performance liquid chromatography with UV detection (HPLC-UV) has been developed for routine analysis of psoralen and bergapten, photosensitizing compounds, in oral solutions of phytomedicines employed in Brazil for some illnesses. The linearity, accuracy, the inter- and intra-day precision of the procedure were evaluated. Calibration curves for psoralen and bergapten were linear in the range of 1.0-600.0 microg ml(-1) and 1.0-400.0 microg ml(-1) respectively. The recoveries of the psoralens in the oral solutions analysed were 94.43-99.97%. The percentage coefficient of variation (CV) of the quantitative analysis of the psoralens in the products analysis was within 5%. In inter-equipment study was employed gas chromatography-flame ionization (CG-FID) detection.

Development and validation of an LC-MS method for determination of Karanjin in rat plasma: application to preclinical pharmacokinetics.

PubMed

Yi, Deliang; Wang, Zhihua; Yi, Longzhi

2015-04-01

A selective and sensitive liquid chromatography-mass spectrometry (MS) method was developed and validated for the determination of karanjin in rat plasma. The target analyte, together with the internal standard (warfarin), was extracted from rat plasma by liquid-liquid extraction with ethyl acetate. Chromatographic separation was performed on a ZORBAX SB-C18 column using a mixture of acetonitrile and 0.1% aqueous formic acid as the mobile phase with linear gradient elution. MS detection was performed on a single quadrupole MS by selected ion monitoring mode via a positive electrospray ionization source. The assay exhibited a linear dynamic range of 2.50-3,000 ng/mL for karanjin. The intra- and inter-day precision was <10.8%, and the intra- and inter-day accuracy was <9.2%. The validated method has been applied to the preclinical pharmacokinetic studies of karanjin following oral administration of 5, 10 and 20 mg/kg karanjin to rats. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

PubMed

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

2012-12-28

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

Multiple Reaction Monitoring Enables Precise Quantification of 97 Proteins in Dried Blood Spots*

PubMed Central

Chambers, Andrew G.; Percy, Andrew J.; Yang, Juncong; Borchers, Christoph H.

2015-01-01

The dried blood spot (DBS) methodology provides a minimally invasive approach to sample collection and enables room-temperature storage for most analytes. DBS samples have successfully been analyzed by liquid chromatography multiple reaction monitoring mass spectrometry (LC/MRM-MS) to quantify a large range of small molecule biomarkers and drugs; however, this strategy has only recently been explored for MS-based proteomics applications. Here we report the development of a highly multiplexed MRM assay to quantify endogenous proteins in human DBS samples. This assay uses matching stable isotope-labeled standard peptides for precise, relative quantification, and standard curves to characterize the analytical performance. A total of 169 peptides, corresponding to 97 proteins, were quantified in the final assay with an average linear dynamic range of 207-fold and an average R2 value of 0.987. The total range of this assay spanned almost 5 orders of magnitude from serum albumin (P02768) at 18.0 mg/ml down to cholinesterase (P06276) at 190 ng/ml. The average intra-assay and inter-assay precision for 6 biological samples ranged from 6.1–7.5% CV and 9.5–11.0% CV, respectively. The majority of peptide targets were stable after 154 days at storage temperatures from −20 °C to 37 °C. Furthermore, protein concentration ratios between matching DBS and whole blood samples were largely constant (<20% CV) across six biological samples. This assay represents the highest multiplexing yet achieved for targeted protein quantification in DBS samples and is suitable for biomedical research applications. PMID:26342038

Reliability of real-time ultrasound measurement of transversus abdominis thickness in healthy trained subjects.

PubMed

Gnat, Rafael; Saulicz, Edward; Miądowicz, Barbara

2012-08-01

To investigate intra- and inter-rater reliability of the ultrasound measurement of transversus abdominis (TrA) thickness and thickness change (difference between thickness at rest and during contraction) in asymptomatic, trained subjects. To define the number of repeated measurements that provide acceptable level of reliability. To investigate variability of the measurements over time of 5 days and the reliability of duplicate analysis of images. A single-group repeated-measures design was used to assess reliability. Healthy volunteers (n = 10) were subjected to 1-week training in voluntary activation of TrA. Real-time ultrasound imaging and subsequent measurement of the TrA thickness at rest and during voluntary contraction were repeated on Monday, Wednesday and Friday of the next week. Using a single repeated measurement, intraclass correlation coefficients (ICCs) for TrA thickness were: 0.86-0.95 (intra-rater), 0.86-0.92 (inter-rater); and for TrA thickness change: 0.34-0.56 (intra-rater), 0.47-0.61 (inter-rater). Using the mean of three repeated measurements respective values were: 0.97, 0.96-0.98; and 0.81-0.84, 0.80-0.90. No significant differences were found between mean values of TrA thickness as well as thickness change obtained on three consecutive measurement days. Duplicate analysis of the images was highly reliable with ICCs of 0.89-0.99. Two repeated measurements for TrA thickness and at least three measurements for TrA thickness change are needed to achieve acceptable levels of intra- and inter-rater reliability. In healthy trained volunteers TrA thickness and thickness change are relatively stable parameters over a 5-day period. Duplicate analysis of the same images by two blinded observers is reliable.

Microscale chemistry-based design of eco-friendly, reagent-saving and efficient pharmaceutical analysis: a miniaturized Volhard's titration for the assay of sodium chloride.

PubMed

Rojanarata, Theerasak; Sumran, Krissadecha; Nateetaweewat, Paksupang; Winotapun, Weerapath; Sukpisit, Sirarat; Opanasopit, Praneet; Ngawhirunpat, Tanasait

2011-09-15

This work demonstrates the extended application of microscale chemistry which has been used in the educational discipline to the real analytical purposes. Using Volhard's titration for the determination of sodium chloride as a paradigm, the reaction was downscaled to less than 2 mL conducted in commercially available microcentrifuge tubes and using micropipettes for the measurement and transfer of reagents. The equivalence point was determined spectrophotometrically on the microplates which quickened the multi-sample measurements. After the validation and evaluation with bulk and dosage forms, the downsized method showed good accuracy comparable to the British Pharmacopeial macroscale method and gave satisfactory precision (intra-day, inter-day, inter-analyst and inter-equipment) with the relative standard deviation of less than 0.5%. Interestingly, the amount of nitric acid, silver nitrate, ferric alum and ammonium thiocyanate consumed in the miniaturized titration was reduced by the factors of 25, 50, 50 and 215 times, respectively. The use of environmentally dangerous dibutyl phthalate was absolutely eliminated in the proposed method. Furthermore, the release of solid waste silver chloride was drastically reduced by about 25 folds. Therefore, microscale chemistry is an attractive, facile and powerful green strategy for the development of eco-friendly, safe, and cost-effective analytical methods suitable for a sustainable environment. Copyright © 2011 Elsevier B.V. All rights reserved.

Development and validation of a sensitive LC-MS/MS method with electrospray ionization for quantitation of pramipexole in human plasma: application to a clinical pharmacokinetic study.

PubMed

Bharathi, D Vijaya; Hotha, Kishore Kumar; Sagar, P V Vidya; Kumar, S Sirish; Naidu, A; Mullangi, Ramesh

2009-02-01

A highly sensitive and specific LC-MS/MS method has been developed and validated for the estimation of pramipexole (PPX) with 500 microL human plasma using memantine as an internal standard (IS). The API-4000 was operated under multiple-reaction monitoring mode (MRM) using the electrospray ionization technique. Solid-phase extraction was used to extract PPX and IS from human plasma. The resolution of peaks was achieved with 0.01 m ammonium acetate buffer (pH 4.4):acetonitrile (30:70, v/v) on a Discovery CN column. The total chromatographic run time was 3.0 min and the elution of PPX and IS occurred at approximately 2.32 and 2.52, respectively. The MS/MS ion transitions monitored were 212.10 --> 153.10 for PPX and 180.20 --> 107.30 for IS. The method was proved to be accurate and precise at linearity range of 20-3540 pg/mL with a correlation coefficient (r) of > or =0.999. The intra- and inter-day precision and accuracy values found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers following oral administration of 0.25 mg PPX tablet. Copyright (c) 2008 John Wiley & Sons, Ltd.

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

PubMed

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

2018-05-01

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

Determination of caprolactam and 6-aminocaproic acid in human urine using hydrophilic interaction liquid chromatography-tandem mass spectrometry.

PubMed

Wu, Ya-Hsueh; Wu, Ming-Ling; Lin, Chun-Chi; Chu, Wei-Lan; Yang, Chen-Chang; Lin, Robert Tate; Deng, Jou-Fang

2012-02-15

A simple and rapid assay based on hydrophilic interaction liquid chromatography with tandem mass spectrometry has been first developed and validated for simultaneous determination of caprolactam (CA) and 6-aminocaproic acid (6-ANCA) in human urine using 8-aminocaprylic acid as internal standard. A 20μL aliquot of urine was injected directly into the liquid chromatography tandem mass spectrometry (LC-MS-MS) system. The analytes were separated on a Phenomenex Luna HILIC column with gradient elution. Detection was performed on Triple Quadrupole LC-MS in positive ions multiple reaction monitoring mode using electrospray ionization. The calibration curves were linear (r(2)≥0.995) over the concentration range from 62.5 to 1250ng/mL for CA and 31.25 to 1000ng/mL for 6-ANCA. The detection limits of CA and 6-ANCA were 62.5 and 15.6ng/mL, respectively. The intra-day and inter-day precisions were within 8.7% and 9.9%, respectively. The intra-day and inter-day accuracy were between 5.3% and 3.5%, and between 6.1% and 6.6%, respectively. The method proved to be simple and time efficient, and was successfully applied to evaluate the kinetics of caprolactam in one unusual case of caprolactam poisoning. Copyright © 2011 Elsevier B.V. All rights reserved.

Quantitative determination of major alkaloids in Cinchona bark by Supercritical Fluid Chromatography.

PubMed

Murauer, Adele; Ganzera, Markus

2018-06-15

Chinoline alkaloids found in Cinchona bark still play an important role in medicine, for example as antimalarial and antiarrhythmic drugs. For the first time Supercritical Fluid Chromatography has been utilized for their separation. Six respective derivatives (dihydroquinidine, dihydroquinine, quinidine, quinine, cinchonine and cinchonidine) could be resolved in less than 7 min, and three of them quantified in crude plant extracts. The optimum stationary phase showed to be an Acquity UPC 2 Torus DEA 1.7 μm column, the mobile phase comprised of CO 2 , acetonitrile, methanol and diethylamine. Method validation confirmed that the procedure is selective, accurate (recovery rates from 97.2% to 103.7%), precise (intra-day ≤2.2%, inter-day ≤3.0%) and linear (R 2  ≥ 0.999); at 275 nm the observed detection limits were always below 2.5 μg/ml. In all of the samples analyzed cinchonine dominated (1.87%-2.30%), followed by quinine and cinchonidine. Their total content ranged from 4.75% to 5.20%. These values are in good agreement with published data, so that due to unmatched speed and environmental friendly character SFC is definitely an excellent alternative for the analysis of these important natural products. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

[Determination of 1-methylhydantoin Concentration in Blood by GC-MS Method and Its Application in Forensic Medicine].

PubMed

Gao, L N; Yuan, H Y; Xu, E Y; Liu, J T

2017-12-01

To establish a gas chromatographic-mass spectrometric （GC-MS） analysis method for quantifying 1-methylhydantoin concentration in whole blood. To provide technical support to forensic identification related cases of 1-methylhydantoin. As an internal standard, 500 ng SKF 525A was added to 0.5 mL blood sample, and then 2 mL 0.01 mol/L dilute hydrochloric acid and 0.5 g ammonium carbonate were added in order to buffer the pH value to 9, and following 2 mL ethyl acetate. The organic solvent layer was obtained after centrifuge and then analysed by GC-MS after drying. Good linear relationship of 1-methylhydantoin in blood was obtained in the range of 0.5-50 ng/mL. The equation of linear regression was y =0.015 51 x +0.007 26（ R ²=0.999 7） with 0.1 ng/mL detection limit, and the recovery was 93.02%-108.12%. The intra-day and inter-day precision were less than 6.07% and 13.37%, respectively. The results gotten by this method is accurate and reproducible, which can be used for the determination of 1-methylhydantoin concentration in blood samples. Copyright© by the Editorial Department of Journal of Forensic Medicine

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

PubMed

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

2018-08-01

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

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.

A sensitive fluorescent nanosensor for chloramphenicol based on molecularly imprinted polymer-capped CdTe quantum dots.

PubMed

Amjadi, Mohammad; Jalili, Roghayeh; Manzoori, Jamshid L

2016-05-01

A novel fluorescent nanosensor using molecularly imprinted silica nanospheres embedded CdTe quantum dots (CdTe@SiO2 @MIP) was developed for detection and quantification of chloramphenicol (CAP). The imprinted sensor was prepared by synthesis of molecularly imprinting polymer (MIP) on the hydrophilic CdTe quantum dots via reverse microemulsion method using small amounts of solvents. The resulting CdTe@SiO2 @MIP nanoparticles were characterized by fluorescence, UV-vis absorption and FT-IR spectroscopy and transmission electron microscopy. They preserved 48% of fluorescence quantum yield of the parent quantum dots. CAP remarkably quenched the fluorescence of prepared CdTe@SiO2 @MIP, probably via electron transfer mechanism. Under the optimal conditions, the relative fluorescence intensity of CdTe@SiO2 @MIP decreased with increasing CAP by a Stern-Volmer type equation in the concentration range of 40-500 µg L(-1). The corresponding detection limit was 5.0 µg L(-1). The intra-day and inter-day values for the precision of the proposed method were all <4%. The developed sensor had a good selectivity and was applied to determine CAP in spiked human and bovine serum and milk samples with satisfactory results. Copyright © 2015 John Wiley & Sons, Ltd.

Melanine value in the stria vascularis of pigmented guinea-pigs treated by kanamycin.

PubMed

Attard, A; Gratacap, B; Charachon, R; Stoebner, P; Laurent, A

1988-01-01

In a previous report, kanamycin (400 mg/kg/d) seemed to increase the number of melanine granulations in intermediate cells of the stria vascularis, especially in the second and third turns. To precise these data, melanine was studied in those turns by ultrastructural morphometry in a control group with 12 animals. We observed a large intra-individual and inter-individual variation before intoxication. Thus, the meaning of melanine modifications by kanamycin must be carefully evaluated.

Comparative analysis of Sambucus nigra and Sambucus australis flowers: development and validation of an HPLC method for raw material quantification and preliminary stability study.

PubMed

Scopel, Marina; Mentz, Lílian Auler; Henriques, Amélia Teresinha

2010-07-01

This work was designed to develop a simple, effective, and reliable LC system to identify a chemical marker and compare Sambucus nigra L. and Sambucus australis Cham. et Schltdl. flower extracts (American and European elder). Rutin was the main constituent of both species. The developed method showed a linear response in the range of 10 to 45 microg x mL(-1) for rutin and 1.75 to 3.25 microg x mL(-1) for samples of the Sambucus species. Precision was determined and the relative standard deviations were 1.75 % for HSN and 1.28 % for HSA for intraday precision and 1.28 % and 1.51 % for inter-day precision, respectively, while accuracy was 97.9 % for HSN and 99.41 % for HSA. Quantification and detection limits as well as robustness were determined, presenting adequate results. The LC method showed an adequate performance for the separation of flavonoid glycosides in S. nigra and S. australis extracts, since the presence of interference had been previously evaluated. The analysis of thirty different samples of S. NIGRA and S. australis of different origins did not show significant variability among them. An accelerated stability study revealed a significant decrease in the first 30 days reaching 57 % in 90 days for S. australis samples and a total decrease of 25 % in 90 days for S. nigra samples, considering rutin as the chemical marker. These results will contribute to quality control analysis routines of these raw materials in pharmaceutical production facilities. Georg Thieme Verlag KG Stuttgart.New York.

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

PubMed

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

2014-01-01

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

[The development and validation of the methods for the quantitative determination of sibutramine derivatives in dietary supplements].

PubMed

Stern, K I; Malkova, T L

The objective of the present study was the development and validation of sibutramine demethylated derivatives, desmethyl sibutramine and didesmethyl sibutramine. Gas-liquid chromatography with the flame ionization detector was used for the quantitative determination of the above substances in dietary supplements. The conditions for the chromatographic determination of the analytes in the presence of the reference standard, methyl stearate, were proposed allowing to achieve the efficient separation. The method has the necessary sensitivity, specificity, linearity, accuracy, and precision (on the intra-day and inter-day basis) which suggests its good validation characteristics. The proposed method can be employed in the analytical laboratories for the quantitative determination of sibutramine derivatives in biologically active dietary supplements.

QuEChERS-based purification method coupled to ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to determine six quaternary ammonium compounds (QACs) in dairy products.

PubMed

Xian, Yanping; Dong, Hao; Wu, Yuluan; Guo, Xindong; Hou, Xiangchang; Wang, Bin

2016-12-01

QuEChERS-based purification coupled with UPLC-MS/MS method, was developed for six quaternary ammonium compounds (QACs) determination in dairy products. Powder samples were firstly dispersed by water. Protein in liquid milk was precipitated and sample solution was extracted by acetonitrile. QuEChERS-based purification was used to purify the solution. QACs were finally separated by HILIC column and detected in MRM mode of MS/MS under ESI(+). The stable isotope benzyl-2,3,4,5,6-d5-dimethyltetradecylammonium bromide (C14-BAC-d5) was used as an internal standard. This method was validated in terms of linearity, sensitivity, precision, accuracy. Linear relations were favorable for QACs over the selected concentration ranges of 0.2-50μg/L, with correlation coefficients greater than 0.999. The limits of detection (LODs) were in the range of 0.4-14.5μg/kg. Recoveries were between 91.2% and 115% with RSDs of 2.8-7.5% for intra-day precision and 3.7-6.7% for inter-day precision. This validated method was successfully applied to determine the QACs concentrations in dairy products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sources of variation in the determination of distal blood pressure measured using the strain gauge technique.

PubMed

Arveschoug, A K; Revsbech, P; Brøchner-Mortensen, J

1998-07-01

Using the determination of distal blood pressure (DBP) measured using the strain gauge technique as an example of a routine clinical physiological investigation involving many different observers (laboratory technicians), the present study was carried out to assess (1) the influence of the number of observers and the number of analyses made by each observer on the precision of a definitive value; and (2) the minimal difference between two determinations to detect a real change. A total of 45 patients participated in the study. They were all referred for DBP determination on suspicion of arterial peripheral vascular disease. In 30 of the patients, the DBP curves were read twice, with a 5-week interval, by 10 laboratory technicians. The results were analysed using the variance component model. The remaining 15 patients had their DBP determined twice on two different days with an interval of 1-3 days and the total day-to-day variation (SDdiff) of DBP was determined. The inter- and intraobserver variations were, respectively, 5.7 and 4.9 mmHg at ankle level and 3.5 and 2.7 mmHg at toe level. The index values as related to systolic pressure were somewhat lower. The mean day-to-day variation was 11 mmHg at ankle level and 10 mmHg at toe level, thereby giving a minimal significant difference between two DBP determinations of 22 mmHg at ankle and 20 mmHg at toe level. To decrease the value of SD (standard deviation) on a definitive determination of DBP and index values, it was slightly more effective if the value was based on two observers performing one independent DBP curve reading than if one observer made one or two DBP curve readings. The reduction in SDdiff was greatest at ankle level. The extent of the Sddiff decrease was greatest when two different observers made a single DBP reading each at both determinations compared with one different observer making two readings at each determination. Surprisingly, about half of the maximum reduction in the SDdiff was achieved just by increasing the number of observers from one to two. We have found variance component analyses to be a suitable method for determining intra- and interobserver variation when several different observers take part in a routine laboratory investigation. It may be applied to other laboratory methods such as renography, isotope cardiography and myocardial perfusion single-photon emission computerized tomography (SPECT) scintigraphy, in which the final result may be affected by individual judgement during processing.

Performance evaluation of elemental analysis/isotope ratio mass spectrometry methods for the determination of the D/H ratio in tetramethylurea and other compounds--results of a laboratory inter-comparison.

PubMed

Bréas, Olivier; Thomas, Freddy; Zeleny, Reinhard; Calderone, Giovanni; Jamin, Eric; Guillou, Claude

2007-01-01

Tetramethylurea (TMU) with a certified D/H ratio is the internal standard for Site-specific Natural Isotope Fractionation measured by Nuclear Magnetic Resonance (SNIF-NMR) analysis of wine ethanol for detection of possible adulterations (Commission Regulation 2676/90). A new batch of a TMU certified reference material (CRM) is currently being prepared. Whereas SNIF-NMR has been employed up to now, Elemental Analysis/Isotope Ratio Mass Spectrometry ((2)H-EA-IRMS) was envisaged as the method of choice for value assignment of the new CRM, as more precise (better repeatable) data might be obtained, resulting in lower uncertainty of the certified value. In order to evaluate the accuracy and intra- and inter-laboratory reproducibility of (2)H-EA-IRMS methods, a laboratory inter-comparison was carried out by analysing TMU and other organic compounds, as well as some waters. The results revealed that experienced laboratories are capable of generating robust and well comparable data, which highlights the emerging potential of IRMS in food authenticity testing. However, a systematic bias between IRMS and SNIF-NMR reference data was observed for TMU; this lack of data consistency rules out the (2)H-IRMS technique for the characterisation measurement of the new TMU CRM.

A Prospective Multicenter Evaluation of the Accuracy of a Novel Implanted Continuous Glucose Sensor: PRECISE II.

PubMed

Christiansen, Mark P; Klaff, Leslie J; Brazg, Ronald; Chang, Anna R; Levy, Carol J; Lam, David; Denham, Douglas S; Atiee, George; Bode, Bruce W; Walters, Steven J; Kelley, Lynne; Bailey, Timothy S

2018-03-01

Persistent use of real-time continuous glucose monitoring (CGM) improves diabetes control in individuals with type 1 diabetes (T1D) and type 2 diabetes (T2D). PRECISE II was a nonrandomized, blinded, prospective, single-arm, multicenter study that evaluated the accuracy and safety of the implantable Eversense CGM system among adult participants with T1D and T2D (NCT02647905). The primary endpoint was the mean absolute relative difference (MARD) between paired Eversense and Yellow Springs Instrument (YSI) reference measurements through 90 days postinsertion for reference glucose values from 40 to 400 mg/dL. Additional endpoints included Clarke Error Grid analysis and sensor longevity. The primary safety endpoint was the incidence of device-related or sensor insertion/removal procedure-related serious adverse events (SAEs) through 90 days postinsertion. Ninety participants received the CGM system. The overall MARD value against reference glucose values was 8.8% (95% confidence interval: 8.1%-9.3%), which was significantly lower than the prespecified 20% performance goal for accuracy (P < 0.0001). Ninety-three percent of CGM values were within 20/20% of reference values over the total glucose range of 40-400 mg/dL. Clarke Error Grid analysis showed 99.3% of samples in the clinically acceptable error zones A (92.8%) and B (6.5%). Ninety-one percent of sensors were functional through day 90. One related SAE (1.1%) occurred during the study for removal of a sensor. The PRECISE II trial demonstrated that the Eversense CGM system provided accurate glucose readings through the intended 90-day sensor life with a favorable safety profile.

Inter-examiner classification reliability of Mechanical Diagnosis and Therapy for extremity problems - Systematic review.

PubMed

Takasaki, Hiroshi; Okuyama, Kousuke; Rosedale, Richard

2017-02-01

Mechanical Diagnosis and Therapy (MDT) is used in the treatment of extremity problems. Classifying clinical problems is one method of providing effective treatment to a target population. Classification reliability is a key factor to determine the precise clinical problem and to direct an appropriate intervention. To explore inter-examiner reliability of the MDT classification for extremity problems in three reliability designs: 1) vignette reliability using surveys with patient vignettes, 2) concurrent reliability, where multiple assessors decide a classification by observing someone's assessment, 3) successive reliability, where multiple assessors independently assess the same patient at different times. Systematic review with data synthesis in a quantitative format. Agreement of MDT subgroups was examined using the Kappa value, with the operational definition of acceptable reliability set at ≥ 0.6. The level of evidence was determined considering the methodological quality of the studies. Six studies were included and all studies met the criteria for high quality. Kappa values for the vignette reliability design (five studies) were ≥ 0.7. There was data from two cohorts in one study for the concurrent reliability design and the Kappa values ranged from 0.45 to 1.0. Kappa values for the successive reliability design (data from three cohorts in one study) were < 0.6. The current review found strong evidence of acceptable inter-examiner reliability of MDT classification for extremity problems in the vignette reliability design, limited evidence of acceptable reliability in the concurrent reliability design and unacceptable reliability in the successive reliability design. Copyright © 2017 Elsevier Ltd. All rights reserved.

Automated GC-MS analysis of free amino acids in biological fluids.

PubMed

Kaspar, Hannelore; Dettmer, Katja; Gronwald, Wolfram; Oefner, Peter J

2008-07-15

A gas chromatography-mass spectrometry (GC-MS) method was developed for the quantitative analysis of free amino acids as their propyl chloroformate derivatives in biological fluids. Derivatization with propyl chloroformate is carried out directly in the biological samples without prior protein precipitation or solid-phase extraction of the amino acids, thereby allowing automation of the entire procedure, including addition of reagents, extraction and injection into the GC-MS. The total analysis time was 30 min and 30 amino acids could be reliably quantified using 19 stable isotope-labeled amino acids as internal standards. Limits of detection (LOD) and lower limits of quantification (LLOQ) were in the range of 0.03-12 microM and 0.3-30 microM, respectively. The method was validated using a certified amino acid standard and reference plasma, and its applicability to different biological fluids was shown. Intra-day precision for the analysis of human urine, blood plasma, and cell culture medium was 2.0-8.8%, 0.9-8.3%, and 2.0-14.3%, respectively, while the inter-day precision for human urine was 1.5-14.1%.

RP-HPLC Method Development and Validation for Determination of Eptifibatide Acetate in Bulk Drug Substance and Pharmaceutical Dosage Forms.

PubMed

Bavand Savadkouhi, Maryam; Vahidi, Hossein; Ayatollahi, Abdul Majid; Hooshfar, Shirin; Kobarfard, Farzad

2017-01-01

A new, rapid, economical and isocratic reverse phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of eptifibatide acetate, a small synthetic antiplatelet peptide, in bulk drug substance and pharmaceutical dosage forms. The developed method was validated as per of ICH guidelines. The chromatographic separation was achieved isocratically on C18 column (150 x 4.60 mm i.d., 5 µM particle size) at ambient temperature using acetonitrile (ACN), water and trifluoroacetic acid (TFA) as mobile phase at flow rate of 1 mL/min and UV detection at 275 nm. Eptifibatide acetate exhibited linearity over the concentration range of 0.15-2 mg/mL (r 2 =0.997) with limit of detection of 0.15 mg/mL The accuracy of the method was 96.4-103.8%. The intra-day and inter-day precision were between 0.052% and 0.598%, respectively. The present successfully validated method with excellent selectivity, linearity, sensitivity, precision and accuracy was applicable for the assay of eptifibatide acetate in bulk drug substance and pharmaceutical dosage forms.

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.

Rapid determination of five antibiotic residues in swine wastewater by online solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Tagiri-Endo, Misako; Suzuki, Shigeru; Nakamura, Tomoyuki; Hatakeyama, Takashi; Kawamukai, Kazuo

2009-02-01

A simple and quick online solid-phase extraction (SPE) coupled to liquid chromatography (LC)/tandem mass spectrometry (MS/MS) for the determination of the five antibiotics (florfenicol, FF; lincomycin, LCM; oxytetracyclin, OTC; tylosin, TS; valnemulin, VLM) in swine wastewater has been developed. After filtration, aliquots (100 microl) of wastewater samples were directly injected to a column-switching LC system. Some matrix interference was removed by washing up SPE column with 0.2% formic acid solution and acetonitrile. Antibiotics eluted from SPE column were separated on analytical column by converting switching valve and were detected by MS/MS. Calibration curves using the method of standard addition had very good correlation coefficients (r > 0.99) in the range of 0.1 to 2 ng/ml. The intra-day precision of the method was less than 12% and the inter-day precision was between 6 to 17%. The detection limits were 0.01-0.1 ng/ml. When this method was applied to wastewater samples in swine facilities, four compounds (LCM, OTC, TS, and VLM) were detected.

Simultaneous determination of phenolic acids and diterpenoids and their comparative pharmacokinetic study in normal and acute blood stasis rats by UFLC-MS/MS after oral administration of Guan-Xin-Shu-Tong capsules.

PubMed

Gao, Xun; Mu, Jingqing; Guan, Shaoyi; Li, Qing; Du, Yiyang; Zhang, Huifen; Bi, Kaishun

2018-01-01

Guan-Xin-Shu-Tong capsules are one of the well-known and first-line Chinese traditional herbal formula for treating coronary heart disease. A validated and sensitive method via ultra fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) was established to simultaneously determinate five phenolic acids and four diterpenoids in rats in order to investigate their pharmacokinetic profiles firstly. Analytes were extracted by ethyl acetate and determined via multiple reaction monitoring mode in both positive and negative ion modes. The values for limit of quantification were in range of 0.025-1.250ng/ml. Inter- and intra-day precisions were no more than 10.9% with accuracy of -11.0%-10.6%, meanwhile the stable and suitable extraction recoveries were also obtained. And finally such excellent method was used to compare the pharmacokinetics of nine compounds in normal and acute blood stasis rats after oral administration of Guan-Xin-Shu-Tong capsules. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of Flurbiprofen in Human Plasma by High-Performance Liquid Chromatography.

PubMed

Yilmaz, Bilal; Erdem, Ali Fuat

2015-10-01

A simple high-performance liquid chromatography method has been developed for determination of flurbiprofen in human plasma. The method was validated on an Ace C18 column using UV detection. The mobile phase was acetonitrile-0.05 M potassium dihydrogen phosphate solution (60:40, v/v) adjusted to pH 3.5 with phosphoric acid. The calibration curve was linear between the concentration range of 0.10-5.0 μg/mL. Intra- and inter-day precision values for flurbiprofen in plasma were <4.47, and accuracy (relative error) was better than 3.67%. The extraction recoveries of flurbiprofen from human plasma were between 93.0 and 98.9%. The limits of detection and quantification of flurbiprofen were 0.03 and 0.10 μg/mL, respectively. In addition, this assay was applied to determine the pharmacokinetic parameters of flurbiprofen in six healthy Turkish volunteers who had been given 100 mg flurbiprofen. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Detection of the Sleep Stages Throughout Non-Obtrusive Measures of Inter-Beat Fluctuations and Motion: Night and Day Sleep of Female Shift Workers

NASA Astrophysics Data System (ADS)

Mendez, Martin O.; Palacios-Hernandez, Elvia R.; Alba, Alfonso; Kortelainen, Juha M.; Tenhunen, Mirja L.; Bianchi, Anna M.

Automatic sleep staging based on inter-beat fluctuations and motion signals recorded through a pressure bed sensor during sleep is presented. The analysis of the sleep was based on the three major divisions of the sleep time: Wake, non-rapid eye movement (nREM) and rapid eye movement (REM) sleep stages. Twelve sleep recordings, from six females working alternate shift, with their respective annotations were used in the study. Six recordings were acquired during the night and six during the day after a night shift. A Time-Variant Autoregressive Model was used to extract features from inter-beat fluctuations which later were fed to a Support Vector Machine classifier. Accuracy, Kappa index, and percentage in wake, REM and nREM were used as performance measures. Comparison between the automatic sleep staging detection and the standard clinical annotations, shows mean values of 87% for accuracy 0.58 for kappa index, and mean errors of 5% for sleep stages. The performance measures were similar for night and day sleep recordings. In this sample of recordings, the results suggest that inter-beat fluctuations and motions acquired in non-obtrusive way carried valuable information related to the sleep macrostructure and could be used to support to the experts in extensive evaluation and monitoring of sleep.

Measurement of methionine level with the LC-ESI-MS/MS method in schizophrenic patients.

PubMed

Kulaksizoglu, S; Kulaksizoglu, B; Ellidag, H Y; Eren, E; Yilmaz, N; Baykal, A

2016-01-01

The purpose of this study was to evaluate plasma methionine levels by using liquid chromatography electrospray ionization-tandem mass spectroscopy (LC-ESI-MS/MS) in schizophrenic patients. A twelve-point standard graph was drawn, and the recovery rate, the intra-day and inter-day coefficients of variation (CV), the limit of detection (LOD), and the limit of quantification (LOQ) were evaluated. The y and R2 values of the standard graph equation were determined as 0.011x + 0.0179 and 0.9989, respectively, and the graph remained linear until the 200 µmol/l level. The intra-day coefficients of variation of the samples (n = 10) containing 8, 28, and 58 µmol/l methionine were determined as 2.68, 3.10, and 3.79%, respectively; while their inter-day coefficients of variation were determined as 2.98, 3.19, and 3.84%. The LOD and LOQ values were determined as 0.04 and 0.1 µmol/l, respectively, while the mean recovery rates were determined as 101.7 and 99.3%. Plasma methionine values were measured as 21.5 (19.5-24,6) µmol/l for the patient group, 17.8 (16.3-20.1) µmol/l for the control group, and the difference between the two groups was statistically significant (p = 0.03). LC-ESI-MS/MS method represents a fairly sensitive, economic, and rapid analysis that requires very little sample and is suitable for measuring methionine levels in schizophrenic patients.

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.

Precise orbit determination of Multi-GNSS constellation including GPS GLONASS BDS and GALIEO

NASA Astrophysics Data System (ADS)

Dai, Xiaolei

2014-05-01

In addition to the existing American global positioning system (GPS) and the Russian global navigation satellite system (GLONASS), the new generation of GNSS is emerging and developing, such as the Chinese BeiDou satellite navigation system (BDS) and the European GALILEO system. Multi-constellation is expected to contribute to more accurate and reliable positioning and navigation service. However, the application of multi-constellation challenges the traditional precise orbit determination (POD) strategy that was designed usually for single constellation. In this contribution, we exploit a more rigorous multi-constellation POD strategy for the ongoing IGS multi-GNSS experiment (MGEX) where the common parameters are identical for each system, and the frequency- and system-specified parameters are employed to account for the inter-frequency and inter-system biases. Since the authorized BDS attitude model is not yet released, different BDS attitude model are implemented and their impact on orbit accuracy are studied. The proposed POD strategy was implemented in the PANDA (Position and Navigation Data Analyst) software and can process observations from GPS, GLONASS, BDS and GALILEO together. The strategy is evaluated with the multi-constellation observations from about 90 MGEX stations and BDS observations from the BeiDou experimental tracking network (BETN) of Wuhan University (WHU). Of all the MGEX stations, 28 stations record BDS observation, and about 80 stations record GALILEO observations. All these data were processed together in our software, resulting in the multi-constellation POD solutions. We assessed the orbit accuracy for GPS and GLONASS by comparing our solutions with the IGS final orbit, and for BDS and GALILEO by overlapping our daily orbit solution. The stability of inter-frequency bias of GLONASS and inter-system biases w.r.t. GPS for GLONASS, BDS and GALILEO were investigated. At last, we carried out precise point positioning (PPP) using the multi-constellation POD orbit and clock products, and analyzed the contribution of these POD products to PPP. Keywords: Multi-GNSS, Precise Orbit Determination, Inter-frequency bias, Inter-system bias, Precise Point Positioning

Reliability of externally fixed dynamometry hamstring strength testing in elite youth football players.

PubMed

Wollin, Martin; Purdam, Craig; Drew, Michael K

2016-01-01

To investigate inter and intra-tester reliability of an externally fixed dynamometry unilateral hamstring strength test, in the elite sports setting. Reliability study. Sixteen, injury-free, elite male youth football players (age=16.81±0.54 years, height=180.22±5.29cm, weight 73.88±6.54kg, BMI=22.57±1.42) gave written informed consent. Unilateral maximum isometric peak hamstring force was evaluated by externally fixed dynamometry for inter-tester, intra-day and intra-tester, inter-week reliability. The test position was standardised to correlate with the terminal swing phase of the gait running cycle. Inter and intra-tester values demonstrated good to high levels of reliability. The intra-class coefficient (ICC) for inter-tester, intra-day reliability was 0.87 (95% CI=0.75-0.93) with standard error of measure percentage (SEM%) 4.7 and minimal detectable change percentage (MDC%) 12.9. Intra-tester, inter-week reliability results were ICC 0.86 (95% CI, 0.74-0.93), SEM% 5.0 and MDC% 14.0. This study demonstrates good to high inter and intra-tester reliability of isometric externally fixed dynamometry unilateral hamstring strength testing in the regular elite sport setting involving elite male youth football players. The intra-class coefficient in association with the low standard error of measure and minimal detectable change percentages suggest that this procedure is appropriate for clinical and academic use as well as monitoring hamstring strength in the elite sport setting. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

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

PubMed

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

2007-02-19

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

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.

Novel liquid chromatography-electrospray ionization mass spectrometry method for the quantification in human urine of microbial aromatic acid metabolites derived from dietary polyphenols.

PubMed

Gonthier, Marie-Paule; Rios, Laurent Y; Verny, Marie- Anne; Rémésy, Christian; Scalbert, Augustin

2003-06-15

An HPLC-ESI-MS-MS method was developed to quantify in human urine fourteen aromatic acids known as metabolites of dietary polyphenols. These metabolites were determined simultaneously in a single 20-min chromatographic analysis with multiple reaction monitoring detection. The inter- and intra-day precisions, calculated from quality control samples were 8.8 and 5.3%, respectively, and the mean accuracy was 2.3%. The method was tested on urine samples collected from one healthy volunteer who consumed a polyphenol-rich diet for 3 days. Increased levels of several aromatic acid metabolites were observed, demonstrating that the method can be used to detect changes in the excretion of microbial metabolites induced by the consumption of polyphenol-containing foods in humans.

Fast and sensitive method to determine parabens by capillary electrophoresis using automatic reverse electrode polarity stacking mode: application to hair samples.

PubMed

Sako, Alysson V F; Dolzan, Maressa D; Micke, Gustavo Amadeu

2015-09-01

This paper describes a fast and sensitive method for the determination of methyl, ethyl, propyl, and butylparaben in hair samples by capillary electrophoresis using automatic reverse electrode polarity stacking mode. In the proposed method, solutions are injected using the flush command of the analysis software (940 mbar) and the polarity switching is carried out automatically immediately after the sample injection. The advantages compared with conventional stacking methods are the increased analytical frequency, repeatability, and inter-day precision. All analyses were performed in a fused silica capillary (50 cm, 41.5 cm in effective length, 50 μm i.d.), and the background electrolyte was composed of 20 mmol L(-1) sodium tetraborate in 10 % of methanol, pH 9.3. For the reverse polarity, -25 kV/35 s was applied followed by application of +30 kV for the electrophoretic run. Temperature was set at 20 °C, and all analytes were monitored at 297 nm. The method showed acceptable linearity (r (2) > 0.997) in the studied range of 0.1-5.0 mg L(-1), limits of detection below 0.017 mg L(-1), and inter-day, intra-day, and instrumental precision better than 6.2, 3.6, and 4.6 %, respectively. Considering parabens is widely used as a preservative in many products and the reported possibility of damage to the hair and also to human health caused by these compounds, the proposed method was applied to evaluate the adsorption of parabens in hair samples. The results indicate that there is a greater adsorption of methylparaben compared to the other parabens tested and also dyed hairs had a greater adsorption capacity for parabens than natural hairs.

Spherical subjective refraction with a novel 3D virtual reality based system.

PubMed

Pujol, Jaume; Ondategui-Parra, Juan Carlos; Badiella, Llorenç; Otero, Carles; Vilaseca, Meritxell; Aldaba, Mikel

To conduct a clinical validation of a virtual reality-based experimental system that is able to assess the spherical subjective refraction simplifying the methodology of ocular refraction. For the agreement assessment, spherical refraction measurements were obtained from 104 eyes of 52 subjects using three different methods: subjectively with the experimental prototype (Subj.E) and the classical subjective refraction (Subj.C); and objectively with the WAM-5500 autorefractor (WAM). To evaluate precision (intra- and inter-observer variability) of each refractive tool independently, 26 eyes were measured in four occasions. With regard to agreement, the mean difference (±SD) for the spherical equivalent (M) between the new experimental subjective method (Subj.E) and the classical subjective refraction (Subj.C) was -0.034D (±0.454D). The corresponding 95% Limits of Agreement (LoA) were (-0.856D, 0.924D). In relation to precision, intra-observer mean difference for the M component was 0.034±0.195D for the Subj.C, 0.015±0.177D for the WAM and 0.072±0.197D for the Subj.E. Inter-observer variability showed worse precision values, although still clinically valid (below 0.25D) in all instruments. The spherical equivalent obtained with the new experimental system was precise and in good agreement with the classical subjective routine. The algorithm implemented in this new system and its optical configuration has been shown to be a first valid step for spherical error correction in a semiautomated way. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

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.

Tutorial on Biostatistics: Linear Regression Analysis of Continuous Correlated Eye Data.

PubMed

Ying, Gui-Shuang; Maguire, Maureen G; Glynn, Robert; Rosner, Bernard

2017-04-01

To describe and demonstrate appropriate linear regression methods for analyzing correlated continuous eye data. We describe several approaches to regression analysis involving both eyes, including mixed effects and marginal models under various covariance structures to account for inter-eye correlation. We demonstrate, with SAS statistical software, applications in a study comparing baseline refractive error between one eye with choroidal neovascularization (CNV) and the unaffected fellow eye, and in a study determining factors associated with visual field in the elderly. When refractive error from both eyes were analyzed with standard linear regression without accounting for inter-eye correlation (adjusting for demographic and ocular covariates), the difference between eyes with CNV and fellow eyes was 0.15 diopters (D; 95% confidence interval, CI -0.03 to 0.32D, p = 0.10). Using a mixed effects model or a marginal model, the estimated difference was the same but with narrower 95% CI (0.01 to 0.28D, p = 0.03). Standard regression for visual field data from both eyes provided biased estimates of standard error (generally underestimated) and smaller p-values, while analysis of the worse eye provided larger p-values than mixed effects models and marginal models. In research involving both eyes, ignoring inter-eye correlation can lead to invalid inferences. Analysis using only right or left eyes is valid, but decreases power. Worse-eye analysis can provide less power and biased estimates of effect. Mixed effects or marginal models using the eye as the unit of analysis should be used to appropriately account for inter-eye correlation and maximize power and precision.

Inter- and intraindividual correlations of background abundances of (2)H, (18)O and (17)O in human urine and implications for DLW measurements.

PubMed

Berman, E S F; Melanson, E L; Swibas, T; Snaith, S P; Speakman, J R

2015-10-01

The method of choice for measuring total energy expenditure in free-living individuals is the doubly labeled water (DLW) method. This experiment examined the behavior of natural background isotope abundance fluctuations within and between individuals over time to assess possible methods of accounting for variations in the background isotope abundances to potentially improve the precision of the DLW measurement. In this work, we measured natural background variations in (2)H, (18)O and (17)O in water from urine samples collected from 40 human subjects who resided in the same geographical area. Each subject provided a urine sample for 30 consecutive days. Isotopic abundances in the samples were measured using Off-Axis Integrated Cavity Output Spectroscopy. Autocorrelation analyses demonstrated that the background isotopes in a given individual were not temporally correlated over the time scales of typical DLW studies. Using samples obtained from different individuals on the same calendar day, cross-correlation analyses demonstrated that the background variations of different individuals were not correlated in time. However, the measured ratios of the three isotopes (2)H, (18)O and (17)O were highly correlated (R(2)=0.89-0.96). Although neither specific timing of DLW water studies nor intraindividual comparisons were found to be avenues for reducing the impact of background isotope abundance fluctuations on DLW studies, strong inter-isotope correlations within an individual confirm that use of a dosing ratio of 8‰:1‰ (0.6 p.p.m.: p.p.m.) optimizes DLW precision. Theoretical implications for the possible use of (17)O measurements within a DLW study require further study.

Profiling of phytohormones and their major metabolites in rice using binary solid-phase extraction and liquid chromatography-triple quadrupole mass spectrometry.

PubMed

Cao, Zhao-Yun; Sun, Li-Hua; Mou, Ren-Xiang; Zhang, Lin-Ping; Lin, Xiao-Yan; Zhu, Zhi-Wei; Chen, Ming-Xue

2016-06-17

A high-throughput method was developed using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) for the profiling and quantification of 43 phytohormones and their major metabolites, including auxins, abscisic acid, jasmonic acid, salicylic acid, cytokinins and gibberellins in a single sample extract. Considerable matrix effects (MEs) were observed (with most ME values in the range of 29%-84%, but maximum MEs of more than 115%, even up to 206%, existed) in sample extracts for most of the compounds studied. The application of the proposed binary solid-phase extraction using polymer anion and polymer cation exchange resins, was performed to purify 25 acidic and 18 alkaline phytohormones and their major metabolites prior to the LC-MS/MS analysis, which markedly reduced the MEs to acceptable levels, with ME values in the range of ±15%. Moreover, all of the isomers of cytokinins and their metabolites were fully separated on a sub-2μm particle C18 reverse-phase column with the optimized mobile phase consisting of methanol and 5mM ammonium formate. The method showed good linearity for all 43 analytes with regression coefficients (R(2))>0.991. Limits of detection ranged from 0.19 to 7.57 fmol for auxin, gibberellins, abscisic acid and their metabolites, 29.7 fmol for jasmonic acid, 18.1 fmol for salicylic acid, and from 0.03 to 0.31 fmol for cytokinins and their metabolites. The mean recoveries for all of the analytes were from 70.7 to 118.5%, and the inter-day precisions (n=6) were less than 18.7%, with intra-day precisions (n=6) within 25.4%. Finally, 20 compounds were successfully quantified in rice sample profiles using the proposed method, which will greatly facilitate the understanding of hormone-related regulatory networks that influence rice growth and development. To our knowledge, there are limited reports that measure this level of phytohormone species in rice samples using a single analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Precision of FLEET Velocimetry Using High-speed CMOS Camera Systems

NASA Technical Reports Server (NTRS)

Peters, Christopher J.; Danehy, Paul M.; Bathel, Brett F.; Jiang, Naibo; Calvert, Nathan D.; Miles, Richard B.

2015-01-01

Femtosecond laser electronic excitation tagging (FLEET) is an optical measurement technique that permits quantitative velocimetry of unseeded air or nitrogen using a single laser and a single camera. In this paper, we seek to determine the fundamental precision of the FLEET technique using high-speed complementary metal-oxide semiconductor (CMOS) cameras. Also, we compare the performance of several different high-speed CMOS camera systems for acquiring FLEET velocimetry data in air and nitrogen free-jet flows. The precision was defined as the standard deviation of a set of several hundred single-shot velocity measurements. Methods of enhancing the precision of the measurement were explored such as digital binning (similar in concept to on-sensor binning, but done in post-processing), row-wise digital binning of the signal in adjacent pixels and increasing the time delay between successive exposures. These techniques generally improved precision; however, binning provided the greatest improvement to the un-intensified camera systems which had low signal-to-noise ratio. When binning row-wise by 8 pixels (about the thickness of the tagged region) and using an inter-frame delay of 65 micro sec, precisions of 0.5 m/s in air and 0.2 m/s in nitrogen were achieved. The camera comparison included a pco.dimax HD, a LaVision Imager scientific CMOS (sCMOS) and a Photron FASTCAM SA-X2, along with a two-stage LaVision High Speed IRO intensifier. Excluding the LaVision Imager sCMOS, the cameras were tested with and without intensification and with both short and long inter-frame delays. Use of intensification and longer inter-frame delay generally improved precision. Overall, the Photron FASTCAM SA-X2 exhibited the best performance in terms of greatest precision and highest signal-to-noise ratio primarily because it had the largest pixels.

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.

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.

Simultaneous estimation of four proton pump inhibitors--lansoprazole, omeprazole, pantoprazole and rabeprazole: development of a novel generic HPLC-UV method and its application to clinical pharmacokinetic study.

PubMed

Bharathi, D Vijaya; Hotha, Kishore Kumar; Jagadeesh, B; Chatki, Pankaj K; Thriveni, K; Mullangi, Ramesh; Naidu, A

2009-07-01

A highly selective, sensitive and accurate HPLC method has been developed and validated for the estimation of four proton-pump inhibitors (PPI), lansoprazole (LPZ), omeprazole (OPZ), pantoprazole (PPZ) and rabeprazole (RPZ), with 500 microL human plasma using zonisamide as an internal standard (IS). The sample preparation involved simple liquid-liquid extraction of LPZ, OPZ, PPZ and RPZ and IS from human plasma with ethyl acetate. The baseline separation of all the peaks was achieved with 0.1% triethylamine (pH 6.0):acetonitrile (72:28, v/v) at a flow rate of 1 mL/min on a Zorbax C(8) column. The total chromatographic run time was 11.0 min and the simultaneous elution of IS, OPZ, RPZ, PPZ and LPZ occurred at approximately 2.42, 4.45, 5.02 and 9.37 min, respectively. The method was proved to be accurate and precise at linearity range of 20.61-1999.79 ng/mL with a correlation coefficient (r) of >or=0.999. The limit of quantitation for each of the PPI studied was 20.61 ng/mL. The intra- and inter-day precision and accuracy values were found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers. (c) 2009 John Wiley & Sons, Ltd.

Validation of a method to detect cocaine and its metabolites in nails by gas chromatography-mass spectrometry.

PubMed

Valente-Campos, Simone; Yonamine, Mauricio; de Moraes Moreau, Regina Lucia; Silva, Ovandir Alves

2006-06-02

The objective of the present work was to compare previously published methods and provide validation data to detect simultaneously cocaine (COC), benzoylecgonine (BE) and norcocaine (NCOC) in nail. Finger and toenail samples (5mg) were cut in very small pieces and submitted to an initial procedure for external decontamination. Methanol (3 ml) was used to release analytes from the matrix. A cleanup step was performed simultaneously by solid-phase extraction (SPE) and the residue was derivatized with pentafluoropropionic anhydride/pentafluoropropanol (PFPA/PFP). Gas chromatography-mass spectrometry (GC-MS) was used to detect the analytes in selected ion monitoring mode (SIM). Confidence parameters of validation of the method were: recovery, intra- and inter-assay precision, as well as limit of detection (LOD) of the analytes. The limits of detection were: 3.5 ng/mg for NCOC and 3.0 ng/mg for COC and BE. Good intra-assay precision was observed for all detected substances (coefficient of variation (CV)<11%). The inter-assay precision for norcocaine and benzoylecgonine were <4%. For intra- and inter-assay precision deuterated internal standards were used. Toenail and fingernail samples from eight declared cocaine users were submitted to the validated method.

High-throughput and cost-effective global DNA methylation assay by liquid chromatography-mass spectrometry

PubMed Central

Li, Xingnan; Franke, Adrian A.

2015-01-01

An affordable and fast liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the accurate and precise determination of global DNA methylation levels in peripheral blood. Global DNA methylation extent was expressed as the ratio of methylated 2′-deoxycytidine (5MedC) to 2′-deoxyguanosine (dG), which were obtained after DNA extraction and hydrolysis and determined by positive electrospray LC–ESI-MS/MS. The cost-effective internal standards 15N3-dC and 15N5-dG were incorporated for the accurate quantification of 5MedC and dG, respectively. The desired nucleoside analytes were separated and eluted by LC within 2.5 min on a reverse phase column with a limit of detection of 1.4 femtomole on column for 5MedC. Sample preparation in 96-well format has significantly increased the assay throughput and filtration was found to be a necessary step to assure precision. Precision was performed with repeated analysis of four DNA QC sample over 12 days, with mean intra- and inter-day CVs of 6% and 11%, respectively. Accuracy was evaluated by comparison with a previously reported method showing a mean CV of 4% for 5 subjects analyzed. Furthermore, application of the assay using a benchtop orbitrap LCMS in exact mass full scan mode showed comparable sensitivity to tandem LCMS using multiple reaction monitoring. PMID:21843675

Development and validation of a sensitive and fast UPLC-MS/MS method for simultaneous determination of seven bioactive compounds in rat plasma after oral administration of Guizhi-gancao decoction.

PubMed

Ji, Bin; Zhuo, Limeng; Yang, Bin; Wang, Yang; Li, Lin; Yu, Miao; Zhao, Yunli; Yu, Zhiguo

2017-04-15

Rapid, sensitive, selective and accurate UPLC-MS/MS method was developed and fully validated for simultaneous determination of cinnamaldehyde, cinnamic acid, 2-methoxy cinnamic acid, glycyrrhizic acid, glycyrrhetinic acid, liquiritigenin and isoliquiritin in rat plasma after oral administration of Guizhi-gancao decoction. Plasma samples were processed with a simple protein precipitation technique using acetonitrile, followed by chromatographic separation using a Thermo Hypersil GOLD C 18 column. A 11.0min linear gradient elution was used at a flow rate of 0.2mL/min with a mobile phase of 0.1% acetic acid containing 0.2mM ammonium acetate in water and acetonitrile. The analytes and internal standard, schisandrin, were detected using both positive and negative ion electrospray ionization in multiple reaction monitoring mode. The developed method was validated for intra-day and inter-day accuracy and precision whose values fell in the acceptable limits. Matrix effect was found to be minimal. Recovery efficiency of all the analytes was found to be >60%. Stability results showed that the analytes were stable at all the conditions. This validated method was successfully used to study the pharmacokinetics of multiple compounds in rat plasma after oral administration of Guizhi-gancao decoction. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed

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

2018-07-13

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

HPLC analysis of para-aminosalicylic acid and its metabolite in plasma, cerebrospinal fluid and brain tissues

PubMed Central

Hong, Lan; Jiang, Wendy; Zheng, Wei; Zeng, Su

2011-01-01

Para-aminosalicylic acid (PAS), an approved drug for treatment of tuberculosis, is a promising therapeutic agent for treatment of manganese (Mn)-induced parkinsonian syndromes. Lack of a quantifying method, however, has hindered the clinical evaluation of its efficacy and thereupon new drug development. This study was aimed at developing a simple and effective method to quantify PAS and its major metabolite, N-acetyl-para-aminosalicylic acid (AcPAS), in plasma, cerebrospinal fluid (CSF) and tissues. Biological samples underwent one-step protein precipitation. The supernatant was fractionated on a reversed-phase C18 column with a gradient mobile system, followed by on-line fluorescence detection. The lower limits of quantification for both PAS and AcPAS were 50 ng/ml of plasma and 17 ng/g of tissues. The intra-day and inter-day precision values did not exceed 5% and 8%, respectively, in all three matrices. The method was used to quantify PAS and AcPAS in rat plasma and brain following a single iv injection of PAS. Data showed a greater amount of PAS than AcPAS in plasma, while a greater amount of AcPAS than PAS was found in brain tissues. The method has been proven to be sensitive, reproducible, and practically useful for laboratory and clinical investigations of PAS in treatment of Mn Parkinsonism. PMID:21159459

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

PubMed

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

2015-01-09

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

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.

Ultrasound-assisted dispersive liquid-liquid microextraction for the determination of seven recreational drugs in human whole blood using gas chromatography-mass spectrometry.

PubMed

Lin, Zebin; Li, Jiaolun; Zhang, Xinyu; Qiu, Meihong; Huang, Zhibin; Rao, Yulan

2017-03-01

Recreational drugs have large impact on public health and security, and to monitor them is of urgent demand. In the present study, ultrasound-assisted dispersive liquid-liquid microextraction combined with the detection of gas chromatography-mass spectrometry was applied to the determination of seven common recreational drugs, including amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, meperidine, methadone and ketamine in 200μL of human whole blood. A series of factors which would affect the extraction efficiency were systematically investigated, including the nature and the volume of extraction and dispersing solvents, ultrasonication time, salting-out effect and pH value. The method consumed small amount of sample. The limits of detection and limits of quantification for each analyte were 10 and 40ng/mL, respectively, and the linearity was in the range of 0.04-25μg/mL (R 2 higher than 0.99). Good specificity, precision (1.5-8.2% for the intra-day study and 2.6-12.8% for the inter-day study), satisfactory accuracy (85.0-117.1%) and extraction recovery (77.0-92.4%) were obtained, which makes it a high performance method for the determination of recreational drugs in human whole blood samples. Copyright © 2017 Elsevier B.V. All rights reserved.

A stability indicating HPLC method for determination of mebeverine in the presence of its degradation products and kinetic study of its degradation in oxidative condition

PubMed Central

Souri, E.; Aghdami, A. Negahban; Adib, N.

2014-01-01

An HPLC method for determination of mebeverine hydrochloride (MH) in the presence of its degradation products was developed. The degradation of MH was studied under hydrolysis, oxidative and photolysis stress conditions. Under alkaline, acidic and oxidative conditions, degradation of MH was observed. The separation was performed using a Symmetry C18 column and a mixture of 50 mM KH2PO4, acetonitrile and tetrahydrfuran (THF) (63:35:2; v/v/v) as the mobile phase. No interference peaks from degradation products in acidic, alkaline and oxidative conditions were observed. The linearity, accuracy and precision of the method were studied. The method was linear over the range of 1-100 μg/ml MH (r2>0.999) and the CV values for intra-day and inter-day variations were in the range of 1.0-1.8%. The limit of quantification (LOQ) and the limit of detection (LOD) of the method were 1.0 and 0.2 μg/ml, respectively. Determination of MH in pharmaceutical dosage forms was performed using the developed method. Furthermore the kinetics of the degradation of MH in the presence of hydrogen peroxide was investigated. The proposed method could be a suitable method for routine quality control studies of mebeverine dosage forms. PMID:25657790

A stability indicating HPLC method for determination of mebeverine in the presence of its degradation products and kinetic study of its degradation in oxidative condition.

PubMed

Souri, E; Aghdami, A Negahban; Adib, N

2014-01-01

An HPLC method for determination of mebeverine hydrochloride (MH) in the presence of its degradation products was developed. The degradation of MH was studied under hydrolysis, oxidative and photolysis stress conditions. Under alkaline, acidic and oxidative conditions, degradation of MH was observed. The separation was performed using a Symmetry C18 column and a mixture of 50 mM KH2PO4, acetonitrile and tetrahydrfuran (THF) (63:35:2; v/v/v) as the mobile phase. No interference peaks from degradation products in acidic, alkaline and oxidative conditions were observed. The linearity, accuracy and precision of the method were studied. The method was linear over the range of 1-100 μg/ml MH (r(2)>0.999) and the CV values for intra-day and inter-day variations were in the range of 1.0-1.8%. The limit of quantification (LOQ) and the limit of detection (LOD) of the method were 1.0 and 0.2 μg/ml, respectively. Determination of MH in pharmaceutical dosage forms was performed using the developed method. Furthermore the kinetics of the degradation of MH in the presence of hydrogen peroxide was investigated. The proposed method could be a suitable method for routine quality control studies of mebeverine dosage forms.

Correlation between Serum Levels of 3,3',5'-Triiodothyronine and Thyroid Hormones Measured by Liquid Chromatography-Tandem Mass Spectrometry and Immunoassay.

PubMed

Sakai, Hiroyuki; Nagao, Hidenori; Sakurai, Mamoru; Okumura, Takako; Nagai, Yoshiyuki; Shikuma, Junpei; Ito, Rokuro; Imazu, Tetsuya; Miwa, Takashi; Odawara, Masato

2015-01-01

For measuring serum 3,3',5'-triiodothyronine (rT3) levels, radioimmunoassay (RIA) has traditionally been used owing to the lack of other reliable methods; however, it has recently become difficult to perform. Meanwhile, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has recently been attracting attention as a novel alternative method in clinical chemistry. To the best of our knowledge, there are no studies to date comparing results of the quantification of human serum rT3 between LC-MS/MS and RIA. We therefore examined the feasibility of LC-MS/MS as a novel alternative method for measuring serum rT3, thyroxine (T4), and 3,5,3'-triiodothyronine (T3) levels. Assay validation was performed by LC-MS/MS using quality control samples of rT3, T4, and T3 at 4 various concentrations which were prepared from reference compounds. Serum samples of 50 outpatients in our department were quantified both by LC-MS/MS and conventional immunoassay for rT3, T4, and T3. Correlation coefficients between the 2 measurement methods were statistically analyzed respectively. Matrix effects were not observed with our method. Intra-day and inter-day precisions were less than 10.8% and 9.6% for each analyte at each quality control level, respectively. Intra-day and inter-day accuracies were between 96.2% and 110%, and between 98.3% and 108.6%, respectively. The lower limit of quantification was 0.05 ng/mL. Strong correlations were observed between the 2 measurement methods (correlation coefficient, T4: 0.976, p < 0.001; T3: 0.912, p < 0.001; rT3: 0.928, p < 0.001). Our LC-MS/MS system requires no manual cleanup operation, and the process after application of a sample is fully automated; furthermore, it was found to be highly sensitive, and superior in both precision and accuracy. The correlation between the 2 methods over a wide range of concentrations was strong. LC-MS/MS is therefore expected to become a useful tool for clinical diagnosis and research.

[Clinical and radiographic outcomes of navigation-assisted versus conventional total knee arthroplasty].

PubMed

Li, Xiaohui; Yu, Jianhua; Gong, Yuekun; Ren, Kaijing; Liu, Jun

2015-04-21

To assess the early postoperative clinical and radiographic outcomes after navigation-assisted or standard instrumentation total knee arthroplasty (TKA). From August 2007 to May 2008, 60 KSS-A type patients underwent 67 primary TKA operations by the same surgical team. Twenty-two operations were performed with the Image-free navigation system with an average age of 64.5 years while the remaining 45 underwent conventional manual procedures with an average age of 66 years. Their preoperative demographic and functional data had no statistical differences (P>0.05). The operative duration, blood loss volume and hospitalization days were compared for two groups. And radiographic data included coronal femoral component angle, coronal tibial component angle, sagittal femoral component angle, sagittal tibial component angle and coronal tibiofemoral angle after one month. And functional assessment scores were evaluated at 1, 3 and 6 months postoperatively. Operative duration was significantly longer for computer navigation (P<0.05). The average blood loss volume was 555.26 ml in computer navigation group and 647.56 ml in conventional manual method group (P<0.05). And hospitalization stay was shorter in computer navigation group than that in conventional method group (7.74 vs 8.68 days) (P=0.04). The alignment deviation was better in computer-assisted group than that in conventional manual method group (P<0.05). The percentage of patients with a coronal tibiofemoral angle within ±3 of ideal value was 95.45% for computer-assisted mini-invasive TKA group and 80% for conventional TKA group (P=0.003). The Knee Society Clinical Rating Score was higher in computer-assisted group than that in conventional manual method group at 1 and 3 montha post-operation. However, no statistical inter-group difference existed at 6 months post-operation. Navigation allows a surgeon to precisely implant the components for TKA. And it offers faster functional recovery and shorter hospitalization stay. At 6 months post-operation, there is no statistical inter-group difference in KSS scores.

Development and validation of an LC-MS/MS method for quantification of cyclic guanosine 3',5'-monophosphate (cGMP) in clinical applications: a comparison with a EIA method.

PubMed

Zhang, Yanhua; Dufield, Dawn; Klover, Jon; Li, Wenlin; Szekely-Klepser, Gabriella; Lepsy, Christopher; Sadagopan, Nalini

2009-02-15

An LC-MS/MS method was developed and validated to quantify endogenous cyclic guanosine 3',5'-monophosphate (cGMP) in human plasma. The LC-MS/MS and competitive enzyme immunoassay (EIA) assays were compared. cGMP concentrations of 20 human plasma samples were measured by both methods. For the MS-based assay, plasma samples were subjected to a simple protein precipitation procedure by acetonitrile prior to analysis by electrospray ionization LC-MS/MS. De-protonated analytes generated in negative ionization mode were monitored through multiple reaction monitoring (MRM). A stable isotope-labeled internal standard, (13)C(10),(15)N(5)-cGMP, which was biosynthesized in-house, was used in the LC-MS/MS method. The competitive EIA was validated using a commercially available cGMP fluorescence assay kit. The intra-assay accuracy and precision for MS-based assay for cGMP were 6-10.1% CV and -3.6% to 7.3% relative error (RE), respectively, while inter-assay precision and accuracy were 5.6-8.1% CV and -2.1% to 6.3% RE, respectively. The intra-assay accuracy and precision for EIA were 17.9-27.1% CV and -4.9% to 24.5% RE, respectively, while inter-assay precision and accuracy were 15.1-39.5% CV and -30.8% to 4.37% RE, respectively. Near the lower limits of detection, there was little correlation between the cGMP concentration values in human plasma generated by these two methods (R(2)=0.197, P=0.05). Overall, the MS-based assay offered better selectivity, recovery, precision and accuracy over a linear range of 0.5-20ng/mL. The LC-MS/MS method provides an effective tool for the quantitation of cGMP to support clinical mechanistic studies of curative pharmaceuticals.

A new MRI grading system for chondromalacia patellae.

PubMed

Özgen, Ali; Taşdelen, Neslihan; Fırat, Zeynep

2017-04-01

Background Chondromalacia patellae is a very common disorder. Although magnetic resonance imaging (MRI) is widely used to investigate patellar cartilage lesions, there is no descriptive MRI-based grading system for chondromalacia patellae. Purpose To propose a new MRI grading system for chondromalacia patellae with corresponding high resolution images which might be useful in precisely reporting and comparing knee examinations in routine daily practice and used in predicting natural course and clinical outcome of the patellar cartilage lesions. Material and Methods High resolution fat-saturated proton density (FS PD) images in the axial plane with corresponding T2 mapping images were reviewed. A detailed MRI grading system covering the deficiencies of the existing gradings has been set and presented on these images. Two experienced observers blinded to clinical data examined 44 knee MR images and evaluated patellar cartilage changes according to the proposed grading system. Inter- and intra-rater validity testing using kappa statistics were calculated. Results A descriptive and detailed grading system with corresponding FS PD and T2 mapping images has been presented. Inter-rater agreement was 0.80 (95% confidence interval [CI], 0.71-0.89). Intra-rater agreements were 0.83 (95% CI, 0.74-0.91) for observer A and 0.79 (95% CI, 0.70-0.88) for observer B (k-values). Conclusion We present a new MRI grading system for chondromalacia patellae with corresponding images and good inter- and intra-rater agreement which might be useful in reporting and comparing knee MRI examinations in daily practice and may also have the potential for using more precisely predicting prognosis and clinical outcome of the patients.

Inter-laboratory comparison study on measuring semi-volatile organic chemicals in standards and air samples.

PubMed

Su, Yushan; Hung, Hayley

2010-11-01

Measurements of semi-volatile organic chemicals (SVOCs) were compared among 21 laboratories from 7 countries through the analysis of standards, a blind sample, an air extract, and an atmospheric dust sample. Measurement accuracy strongly depended on analytes, laboratories, and types of standards and samples. Intra-laboratory precision was generally good with relative standard deviations (RSDs) of triplicate injections <10% and with median differences of duplicate samples between 2.1 and 22%. Inter-laboratory variability, measured by RSDs of all measurements, was in the range of 2.8-58% in analyzing standards, and 6.9-190% in analyzing blind sample and air extract. Inter-laboratory precision was poorer when samples were subject to cleanup processes, or when SVOCs were quantified at low concentrations. In general, inter-laboratory differences up to a factor of 2 can be expected to analyze atmospheric SVOCs. When comparing air measurements from different laboratories, caution should be exercised if the data variability is less than the inter-laboratory differences. 2010. Published by Elsevier Ltd. All rights reserved.

Climatology of the inter-hemispheric field-aligned currents system over the Nigeria ionosphere

NASA Astrophysics Data System (ADS)

Bolaji, O. S.; Rabiu, A. B.; Oyeyemi, E. O.; Yumoto, K.

2012-11-01

Records of the declination (D) magnetic field data for the year 2009 from the Magnetic Data Acquisition System (MAGDAS) facilities at University of Ilorin were employed for this work. From the minutes value of the D-component, the deduced hourly values of the D-component (Sq(QD)) were used to estimate its diurnal (Sq(D)) values with the most five quietest days identified. The monthly mean (MSq(D)) of the most five quietest days and their seasonal (SSq(D)) variabilities were investigated. The inter-hemispheric field aligned currents (IHFACs) exhibit downward and upward inter-hemispheric field-aligned sheet current that appears as a pair at all local times of the Sq(D), MSq(D), and SSq(D) variations. From these variabilities, the IHFACs were observed to flow from the winter to summer hemisphere during noon and dusk sector and flowing in opposite direction during the dawn sector. The Sq(D) variability patterns that were observed in May, June, August September are gentle compared to the disturbed variabilities in January, February, March and November. The highest positive (˜1.7 arc-min) and negative (˜-2.7 arc min) MSq(D) maxima values were observed in August during the dawn and noon sectors respectively. These values indicated that the IHFACs flow in August is strongly southbound (positive) and northbound (negative) in the dawn and noon sectors respectively. Dusk-side IHFACs as can be observed by MAGDAS are weakly northbound in all the seasons. The direction of IHFACs does not flip at the equinoxes but in June and November and does not become largest at solstices but in August. The IHFACs was observed to exhibit longitudinal variability, which indicated that larger amplitude of winter-to-summer IHFACs is observed to be greater in June solstice (northbound/negative IHFACs) than in the December solstice (southbound/positive IHFACs) during the noon sector.

The development and validation of an UHPLC–MS/MS method for the rapid quantification of the antiretroviral agent dapivirine in human plasma

PubMed Central

Seserko, Lauren A; Emory, Joshua F; Hendrix, Craig W; Marzinke, Mark A

2014-01-01

Background Dapivirine is a non-nucleoside reverse transcriptase inhibitor designed to prevent HIV-1 viral replication and subsequent propagation. A sensitive method is required to quantify plasma concentrations to assess drug efficacy. Results Dapivirine-spiked plasma was combined with acetonitrile containing deuterated IS and was processed for analysis. The method has an analytical measuring range from 20 to 10,000 pg/ml. For the LLOQ, low, mid and high QCs, intra- and inter-assay precision (%CV) ranged from 5.58 to 13.89% and 5.23 to 13.36%, respectively, and intra- and inter-day accuracy (% deviation) ranged from -5.61 to 0.75% and -4.30 to 6.24%, respectively. Conclusion A robust and sensitive LC–MS/MS assay for the high-throughput quantification of the antiretroviral drug dapivirine in human plasma was developed and validated following bioanalytical validation guidelines. The assay meets criteria for the analysis of samples from large research trials. PMID:24256358

The development and validation of an UHPLC-MS/MS method for the rapid quantification of the antiretroviral agent dapivirine in human plasma.

PubMed

Seserko, Lauren A; Emory, Joshua F; Hendrix, Craig W; Marzinke, Mark A

2013-11-01

Dapivirine is a non-nucleoside reverse transcriptase inhibitor designed to prevent HIV-1 viral replication and subsequent propagation. A sensitive method is required to quantify plasma concentrations to assess drug efficacy. Dapivirine-spiked plasma was combined with acetonitrile containing deuterated IS and was processed for analysis. The method has an analytical measuring range from 20 to 10,000 pg/ml. For the LLOQ, low, mid and high QCs, intra- and inter-assay precision (%CV) ranged from 5.58 to 13.89% and 5.23 to 13.36%, respectively, and intra- and inter-day accuracy (% deviation) ranged from -5.61 to 0.75% and -4.30 to 6.24%, respectively. A robust and sensitive LC-MS/MS assay for the high-throughput quantification of the antiretroviral drug dapivirine in human plasma was developed and validated following bioanalytical validation guidelines. The assay meets criteria for the analysis of samples from large research trials.

Moon-to-Earth: Eavesdropping on the GRAIL Inter-Spacecraft Time-Transfer Link Using a Large Antenna and a Software Receiver

NASA Technical Reports Server (NTRS)

Esterhuizen, Stephan

2012-01-01

NASA's twin GRAIL [1] spacecraft (Ebb and Flow) arrived at Earth's Moon on New Year's Day, 2012. GRAIL's primary mission is to create a high-resolution map of the Moon's gravitational field by measuring very precisely the change in distance between the two spacecraft [2]. Each spacecraft transmits two signals to the other spacecraft, a PRN code modulated on a 2 GHz carrier (S-band), as well as an unmodulated carrier at roughly 33 GHz (Ka-band). Since it's not feasible to synchronize the two GRAIL spacecraft's clocks via GPS (as was done with GRACE), the S-band signals are used as a time-transfer link to synchronize either Ebb's clock to Flow or vice versa. As an independent measure to determine the clock offset of the GRAIL ultra-stable oscillators to UTC(NIST), an experiment was conducted where our JPL team used a large antenna on Earth to eavesdrop on the inter-spacecraft time-transfer link.

A validated HPLC determination of the flavone aglycone diosmetin in human plasma.

PubMed

Kanaze, Feras Imad; Bounartzi, Melpomeni I; Niopas, Ioannis

2004-12-01

Diosmetin, 3',5,7-trihydroxy-4'-methoxy flavone, is the aglycone of the flavonoid glycoside diosmin that occurs naturally in foods of plant origin. Diosmin exhibits antioxidant and anti-inflammatory activities, improves venous tone and it is used for the treatment of chronic venous insufficiency. Diosmin is hydrolyzed by enzymes of intestinal micro flora before absorption of its aglycone diosmetin. A specific, sensitive, precise, accurate and robust HPLC assay for the determination of diosmetin in human plasma was developed and validated. Diosmetin and the internal standard 7-ethoxycoumarin were isolated from plasma by liquid-liquid extraction and separated on a C8 reversed-phase column with methanol-water-acetic acid (55:43:2, v/v/v) as the mobile phase at 43 degrees C. Peaks were monitored at 344 nm. The method was linear in the 10-300 ng/mL concentration range (r > 0.999). Recovery for diosmetin and internal standard was greater than 89.7 and 86.8%, respectively. Intra-day and inter-day precision for diosmetin ranged from 1.6 to 4.6 and from 2.2 to 5.3%, respectively, and accuracy was better than 97.9%. Copyright 2004 John Wiley & Sons, Ltd.

Determination of the R-enantiomer of valsartan in pharmaceutical formulation by capillary electrophoresis.

PubMed

Lee, Kyung Ran; Nguyen, NgocVan Thi; Lee, Yong Jae; Choi, Seungho; Kang, Jong Seong; Mar, Woongchon; Kim, Kyeong Ho

2015-01-01

Capillary zone electrophoresis was successfully applied to the enantiomeric purity determination of valsartan using acetyl-β-cyclodextrin (A-β-CD) as a chiral selector. Separations were carried out in a 50 µm, 64/56 cm fused-silica capillary. The optimized conditions included 25 mM phosphate buffer, pH 8.0, containing 10 mM A-β-CD as background electrolyte, an applied voltage of +30 kV and a temperature of 30 °C. Ibuprofen was used as an internal standard. The assay was validated for the R-enantiomer of valsartan in the range of 0.05-3.0%. The limit of detection was 0.01%, the limit of quantitation was 0.05%, relative to a concentration of valsartan of 1 mg/ml. Intra-day precision varied between 2.57 and 5.60%. Relative standard deviations of inter-day precision ranged between 4.46 and 6.76% for peak area ratio. The percentage recovery of the R-enantiomer of valsartan ranged between 97.0 and 99.6% in valsartan product. The assay was applied to the determination of the chiral purity of valsartan tablets and R-enantiomer of valsartan was found as an impurity.

RP-HPLC Method Development and Validation for Determination of Eptifibatide Acetate in Bulk Drug Substance and Pharmaceutical Dosage Forms

PubMed Central

Bavand Savadkouhi, Maryam; Vahidi, Hossein; Ayatollahi, Abdul Majid; Hooshfar, Shirin; Kobarfard, Farzad

2017-01-01

A new, rapid, economical and isocratic reverse phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of eptifibatide acetate, a small synthetic antiplatelet peptide, in bulk drug substance and pharmaceutical dosage forms. The developed method was validated as per of ICH guidelines. The chromatographic separation was achieved isocratically on C18 column (150 x 4.60 mm i.d., 5 µM particle size) at ambient temperature using acetonitrile (ACN), water and trifluoroacetic acid (TFA) as mobile phase at flow rate of 1 mL/min and UV detection at 275 nm. Eptifibatide acetate exhibited linearity over the concentration range of 0.15-2 mg/mL (r2=0.997) with limit of detection of 0.15 mg/mL The accuracy of the method was 96.4-103.8%. The intra-day and inter-day precision were between 0.052% and 0.598%, respectively. The present successfully validated method with excellent selectivity, linearity, sensitivity, precision and accuracy was applicable for the assay of eptifibatide acetate in bulk drug substance and pharmaceutical dosage forms. PMID:28979304

Quantitative analysis of a novel HIV fusion inhibitor (sifuvirtide) in HIV infected human plasma using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry.

PubMed

Che, Jinjing; Meng, Qingfang; Chen, Zhihang; Hou, Yunan; Shan, Chengqi; Cheng, Yuanguo

2010-03-11

A sensitive method for measuring sifuvirtide, a novel HIV fusion inhibitor peptide drug in HIV-1(+) human plasma by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. The plasma samples were treated by solvent/detergent (S/D) method to inactivate viral activity before analysis. After protein precipitation sifuvirtide was determined by LC-MS/MS. A structure analog was used as internal standard (IS). The mass spectrometer was operated in positive ion and multiple reaction monitoring mode with transitions m/z 946.3-->159.0 for sifuvirtide and 951.7-->159.2 for IS. The intra-day precision ranged from 2.74% to 7.57% with accuracy from 91.63% to 102.53%. The inter-day precision ranged from 2.65% to 3.58% and the accuracy from 95.53% to 105.28%. Stability studies showed that sifuvirtide was stable both during the assay procedure and long-term storage. The lower limit of quantitation (LLOQ) was 9.75ngml(-1). The method was used for analyzing samples from phase IIa clinical study of sifuvirtide in China. Copyright 2009 Elsevier B.V. All rights reserved.

Chemiluminescence enzyme immunoassay for the determination of sulfamethoxydiazine

NASA Astrophysics Data System (ADS)

Wu, Yongjun; Yu, Songcheng; Yu, Fei; Yan, Nali; Qu, Lingbo; Zhang, Hongquan

2011-10-01

Sulfamethoxydiazine (SMD), which is often used for animal disease treatment, is harmful to human health. No SMD residue should be detected in food in some countries, such as USA and Japan. Therefore, it is significant to develop a high-throughput, high-sensitivity and accurate method for the determination of the content of SMD in food. In this paper, chemiluminescence enzyme immunoassay (CLEIA) was developed for quantification of SMD. For this method, the limit of detection was 3.2 pg/ml, the linear range was from 10 to 2000 pg/ml, the within-day and inter-day precision were below 13% and below 18%, respectively, and the recovery was from 85% to 105%. Milk and egg were selected as samples to be examined with this method, and the result indicated that this CLEIA method was suitable for screening and quality control of food.

Tissue residue depletion of moxidectin in lambs (Ovis aries) following subcutaneous administration.

PubMed

Cruz, Michelle Del Bianchi A; Fernandes, Maria Ângela M; Monteiro, Alda Lúcia G; Teles, Juliana A; Anadón, Arturo; Reyes, Felix G R

2018-06-07

To date, a tissue depletion study of moxidectin (MOX) in lambs is not available. Thus, considering that lamb meat is of great commercial interest in the world, the aim of the present study was to determine the residue levels of MOX in lamb target-tissues (muscle, liver, kidney and fat) and subsequently calculate the MOX withdrawal period. For this purpose, the target-tissues were analysed by ultra-high-performance liquid chromatography-tandem mass spectrometry. Method validation was performed based on Commission Decision 2002/657/EC and VICH GL49. To quantify the analyte, matrix-matched analytical curves were constructed with spiked blank tissues. The limits of detection and quantitation were 1.5 and 5 ng g -1 , respectively, for all matrices. The linearity, decision limit, detection capability accuracy and inter- and intra-day precision of the method are reported. The lambs were treated with a single subcutaneous dose of 0.2 mg MOX kg -1 body weight and were slaughtered in accordance with accepted animal care protocols. Samples of target-tissues were collected on 2, 4, 7, 14, 28 and 42 days after MOX administration. During the whole study, the highest drug residue level occurred in the fat. For the other target-tissues (muscle, liver and kidney), MOX concentrations were below the maximum residue limit (MRL). Considering the MRL value of 500 µg kg -1 for MOX residues in sheep fat, our results in lambs allowed the estimation of a MOX withdrawal period of 31 days. This indicates that the withdrawal period established for MOX in adult sheep (28 days) does not apply for lambs.

Analysis of Correlation between Ionospheric Spatial Gradients and Space Weather Intensity under Nominal Conditions for Ground-Based Augmentation Systems

NASA Astrophysics Data System (ADS)

Lee, J.

2013-12-01

Ground-Based Augmentation Systems (GBAS) support aircraft precision approach and landing by providing differential GPS corrections to aviation users. For GBAS applications, most of ionospheric errors are removed by applying the differential corrections. However, ionospheric correction errors may exist due to ionosphere spatial decorrelation between GBAS ground facility and users. Thus, the standard deviation of ionosphere spatial decorrelation (σvig) is estimated and included in the computation of error bounds on user position solution. The σvig of 4mm/km, derived for the Conterminous United States (CONUS), bounds one-sigma ionospheric spatial gradients under nominal conditions (including active, but not stormy condition) with an adequate safety margin [1]. The conservatism residing in the current σvig by fixing it to a constant value for all non-stormy conditions could be mitigated by subdividing ionospheric conditions into several classes and using different σvig for each class. This new concept, real-time σvig adaptation, will be possible if the level of ionospheric activity can be well classified based on space weather intensity. This paper studies correlation between the statistics of nominal ionospheric spatial gradients and space weather indices. The analysis was carried out using two sets of data collected from Continuous Operating Reference Station (CORS) Network; 9 consecutive (nominal and ionospherically active) days in 2004 and 19 consecutive (relatively 'quiet') days in 2010. Precise ionospheric delay estimates are obtained using the simplified truth processing method and vertical ionospheric gradients are computed using the well-known 'station pair method' [2]. The remaining biases which include carrier-phase leveling errors and Inter-frequency Bias (IFB) calibration errors are reduced by applying linear slip detection thresholds. The σvig was inflated to overbound the distribution of vertical ionospheric gradients with the required confidence level. Using the daily maximum values of σvig, day-to-day variations of spatial gradients are compared to those of two space weather indices; Disturbance, Storm Time (Dst) index and Interplanetary Magnetic Field Bz (IMF Bz). The day-to-day variations of both space weather indices showed a good agreement with those of daily maximum σvig. The results demonstrate that ionospheric gradient statistics are highly correlated with space weather indices on nominal and off-nominal days. Further investigation on this relationship would facilitate prediction of upcoming ionospheric behavior based on space weather information and adjusting σvig in real time. Consequently it will improve GBAS availability by adding external information to operation. [1] Lee, J., S. Pullen, S. Datta-Barua, and P. Enge (2007), Assessment of ionosphere spatial decorrelation for GPS-based aircraft landing systems, J. Aircraft, 44(5), 1662-1669, doi:10.2514/1.28199. [2] Jung, S., and J. Lee (2012), Long-term ionospheric anomaly monitoring for ground based augmentation systems, Radio Sci., 47, RS4006, doi:10.1029/2012RS005016.

Simultaneous determination of cocaine and opiates in dried blood spots by electrospray ionization tandem mass spectrometry.

PubMed

Antelo-Domínguez, Ángel; Cocho, José Ángel; Tabernero, María Jesús; Bermejo, Ana María; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

2013-12-15

A sample pre-treatment method based on blood spot collection filter cards was optimized as a means of using small volume samples for the screening and confirmation of cocaine and opiates abuse. Dried blood spots (DBSs) were prepared by dispersing 20 µL of whole blood specimens previously mixed with the internal standards (deuterated analogs of each target), and subjecting the whole DBS to extraction with 5 mL of methanol under orbital-horizontal shaking (180 rpm) for 10 min. Determinations were based on direct electrospray ionization tandem mass spectrometry (ESI-MS/MS) by injecting the re-dissolved methanol extract with the delivery solution (acetonitrile-water-formic acid, 80:19.875:0.125) at a flow rate of 60 µL min(-1), and using multiple reaction monitoring (MRM) mode with the m/z (precursor ion)→m/z (product ion) transitions for acquisition. Matrix effect has been found to be statistically significant (Multiple Range Test) when assessing cocaine, BZE, codeine and morphine, and the use of the standard addition method (dispersion of whole blood previously mixed with standards onto the filter papers) was needed for accurate determinations. The developed DBS-ESI-MS/MS procedure offered good intra-day and inter-day precisions (lower than 10% and 12%, respectively), as well as good intra-day and inter-day accuracies (inter-day absolute recoveries, expressed as the mean analytical recovery over three target concentration levels, of 103%, 100%, 101%, 98% and 100% for cocaine, BZE, codeine, morphine and 6-MAM, respectively). The high sensitivity inherent to MS/MS determinations combined with the minimal dilution of sample allowed low limits of quantification for all targets, and the developed method results therefore adequate for cocaine and opiates screening and confirmation purposes. The procedure was finally applied to DBSs prepared from whole blood from polydrug abusers, and results were compared with those obtained after a conventional sample pretreatment method based on solid phase extraction for plasma specimens and gas chromatography-mass spectrometry. © 2013 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.

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

PubMed

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

2011-04-01

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

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

PubMed

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

2015-06-01

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

Quantitative determination of dopamine in human plasma by a highly sensitive LC-MS/MS assay: Application in preterm neonates.

PubMed

Zhang, Daping; Wu, Lei; Chow, Diana S-L; Tam, Vincent H; Rios, Danielle R

2016-01-05

The determination of dopamine facilitates better understanding of the complex brain disorders in the central nervous system and the regulation of endocrine system, cardiovascular functions and renal functions in the periphery. The purpose of this study was to develop a highly sensitive and reliable assay for the quantification of dopamine in human neonate plasma. Dopamine was extracted from human plasma by strong cation exchange (SCX) solid phase extraction (SPE), and subsequently derivatized with propionic anhydride. The derivatized analyte was separated by a Waters Acquity UPLC BEH C18 column using gradient elution at 0.4 ml/min with mobile phases A (0.2% formic acid in water [v/v]) and B (MeOH-ACN [v/v, 30:70]). Analysis was performed under positive electrospray ionization tandem mass spectrometer (ESI-MS/MS) in the multiple reaction monitoring (MRM) mode. The stable and relatively non-polar nature of the derivatized analyte enables reliable quantification of dopamine in the range of 10-1000 pg/ml using 200 μl of plasma sample. The method was validated with intra-day and inter-day precision less than 7%, and the intra-day and inter-day accuracy of 91.9-101.9% and 92.3-102.6%, respectively. The validated assay was applied to quantify dopamine levels in two preterm neonate plasma samples. In conclusion, a sensitive and selective LC-MS/MS method has been developed and validated, and successfully used for the determination of plasma dopamine levels in preterm neonates. Copyright © 2015 Elsevier B.V. All rights reserved.

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

PubMed

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

2013-03-25

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

Determination of total and unbound warfarin and warfarin alcohols in human plasma by high performance liquid chromatography with fluorescence detection.

PubMed

Lomonaco, Tommaso; Ghimenti, Silvia; Piga, Isabella; Onor, Massimo; Melai, Bernardo; Fuoco, Roger; Di Francesco, Fabio

2013-11-01

Two analytical procedures are presented for the determination of the total content and unbound fraction of both warfarin and warfarin alcohols in human plasma. Chromatographic separation was carried out in isocratic conditions at 25°C on a C-18 reversed-phase column with a mobile phase consisting of a 70% buffer phosphate 25mM at pH=7, 25% methanol and 5% acetonitrile at a flow rate of 1.2mL/min. Fluorescence detection was performed at 390nm (excitation wavelength 310nm). Neither method showed any detectable interference or matrix effect. Inter-day recovery of the total warfarin and warfarin alcohols at a concentration level of 1000ng/mL was 89±3% and 73±3%, respectively, whereas for their unbound fraction (at a concentration level of 10ng/mL) was 66±8% and 90±7%, respectively. The intra- and inter-day precision (assessed as relative standard deviation) was <10% for both methods. The limits of detection were 0.4 and 0.2ng/mL for warfarin and warfarin alcohols, respectively. The methods were successfully applied to a pooled plasma sample obtained from 69 patients undergoing warfarin therapy. Copyright © 2013 Elsevier B.V. All rights reserved.

Reliability of doming and toe flexion testing to quantify foot muscle strength.

PubMed

Ridge, Sarah Trager; Myrer, J William; Olsen, Mark T; Jurgensmeier, Kevin; Johnson, A Wayne

2017-01-01

Quantifying the strength of the intrinsic foot muscles has been a challenge for clinicians and researchers. The reliable measurement of this strength is important in order to assess weakness, which may contribute to a variety of functional issues in the foot and lower leg, including plantar fasciitis and hallux valgus. This study reports 3 novel methods for measuring foot strength - doming (previously unmeasured), hallux flexion, and flexion of the lesser toes. Twenty-one healthy volunteers performed the strength tests during two testing sessions which occurred one to five days apart. Each participant performed each series of strength tests (doming, hallux flexion, and lesser toe flexion) four times during the first testing session (twice with each of two raters) and two times during the second testing session (once with each rater). Intra-class correlation coefficients were calculated to test for reliability for the following comparisons: between raters during the same testing session on the same day (inter-rater, intra-day, intra-session), between raters on different days (inter-rater, inter-day, inter-session), between days for the same rater (intra-rater, inter-day, inter-session), and between sessions on the same day by the same rater (intra-rater, intra-day, inter-session). ICCs showed good to excellent reliability for all tests between days, raters, and sessions. Average doming strength was 99.96 ± 47.04 N. Average hallux flexion strength was 65.66 ± 24.5 N. Average lateral toe flexion was 50.96 ± 22.54 N. These simple tests using relatively low cost equipment can be used for research or clinical purposes. If repeated testing will be conducted on the same participant, it is suggested that the same researcher or clinician perform the testing each time for optimal reliability.

A HPLC-UV method for the determination of puerarin in rat plasma after intravenous administration of PEGylated puerarin conjugate.

PubMed

Liu, Xinyi; Zhi, Hongying; Du, Feng; Ye, Zuguang; Wang, Naijie; Qin, Wenjie; Li, Jianrong

2010-12-01

A sensitive and reproducible HPLC method for quantitative determination of puerarin (PUE) in rat plasma was developed and validated using 4-hydroxybenzaldehyde as an internal standard. The separation of PUE was performed on a CAPCELL PAK C18 column by gradient elution with 0.2% aqueous phosphoric acid and acetonitrile as the mobile phase. The method was validated and found to be linear in the range of 80-12,000ng/mL. The limit of quantification was 80ng/mL based on 100μL of plasma. The variations for intra- and inter-day precision were less than 8.3%, and the accuracy values were between 98% and 105.2%. The extraction recoveries were more than 85%. The method was successfully applied in the comparative study of pharmacokinetics of PEGylated puerarin (PEG-PUE) versus PUE in rats. Compared with PUE, PEG-PUE showed a 5.2-fold increase in half-life of PUE and a 4.7-fold increase in mean residence time. In addition, this method was also successfully applied to determine the low plasma concentration of PUE regenerated from PEG-PUE in vitro. Copyright © 2010 Elsevier B.V. All rights reserved.

Magnetic solid phase extraction and static headspace gas chromatography-mass spectrometry method for the analysis of polycyclic aromatic hydrocarbons.

PubMed

Cai, Ying; Yan, Zhihong; Wang, Lijia; NguyenVan, Manh; Cai, Qingyun

2016-01-15

A magnetic solid phase extraction (MSPE) protocol combining a static headspace gas chromatography coupled to mass spectrometry (HS-GC-MS) method has been developed for extraction, and determination of 16 polycyclic aromatic hydrocarbons (PAHs) in drinking water samples. Magnetic nanoparticles (MNPs) were coated with 3-aminopropyltriethoxysilane and modified by cholesterol chloroformate. Transmission electron microscope, vibrating sample magnetometer, Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy were used to characterize the cholesterol-functionalized sorbents, and the main parameters affecting the extraction as well as HS sampling, such as sorbent amount, extraction time, oven temperature and equilibration time have been investigated and established. Combination with HS sampling, the MSPE procedure was simple, fast and environmentally friendly, without need of any organic solvent. Method validation proved the feasibility of the developed sorbents for the quantitation of the investigated analytes at trace levels obtaining the limit of detection (S/N=3) ranging from 0.20 to 7.8 ng/L. Good values for intra and inter-day precision were obtained (RSDs ≤ 9.9%). The proposed method was successfully applied to drinking water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Development and validation of a rapid resolution liquid chromatography method for the screening of dietary plant isoprenoids: carotenoids, tocopherols and chlorophylls.

PubMed

Stinco, Carla M; Benítez-González, Ana M; Hernanz, Dolores; Vicario, Isabel M; Meléndez-Martínez, Antonio J

2014-11-28

A rapid resolution liquid chromatography (RRLC) method was developed and validated for the simultaneous determination of nine carotenoids compounds (violaxanthin, lutein, zeaxanthin, β-cryptoxanthin, α-carotene, β-carotene, lycopene, phytoene, phytofluene), four tocopherols and four chlorophylls and derivates (chlorophylls and pheophytins). The methodology consisted in a micro-extraction procedure with or without saponification and subsequent analysis by RRLC. The limits of detection were <0.07 μg for carotenoids and tocopherols and <0.08 μg for chlorophylls and derivatives. The overall precision values (intra- and inter-day) were lower than 12% when samples were not saponified and <27.6%, when the saponification step was performed. The recovery of the method without the saponification step ranged from 92% to 107%, whilst that when saponification was carried out ranged from 60% for α-tocopherol to 82% for β-carotene. Finally, the applicability of the method was demonstrated by the identification and quantification of isoprenoids in different samples. The methodology is appropriate for the high-throughput screening of dietary isoprenoids in fruits and vegetables. Copyright © 2014 Elsevier B.V. All rights reserved.

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

PubMed

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

2015-04-15

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

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.

Estrogens determination in wastewater samples by automatic in-syringe dispersive liquid-liquid microextraction prior silylation and gas chromatography.

PubMed

González, Alba; Avivar, Jessica; Cerdà, Víctor

2015-09-25

A new procedure for the extraction, preconcentration and simultaneous determination of the estrogens most used in contraception pharmaceuticals (estrone, 17β-estradiol, estriol, and 17α-ethynylestradiol), cataloged as Contaminants of Emergent Concern by the Environmental Protection Agency of the United States (US-EPA), is proposed. The developed system performs an in-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction (in-syringe-MSA-DLLME) prior derivatization and gas chromatography (GC-MS). Different extraction (carbon tetrachloride, ethyl acetate, chloroform and trichloroethylene) and disperser solvents (acetone, acetonitrile and methanol) were tested. Chloroform and acetone were chosen as extraction and disperser solvent, respectively, as they provided the best extraction efficiency. Then, a multivariate optimization of the extraction conditions was carried out. Derivatization conditions were also studied to ensure the conversion of the estrogens to their respective trimethylsilyl derivatives. Low LODs and LOQs were achieved, i.e. between 11 and 82ngL(-1), and 37 and 272ngL(-1), respectively. Good values for intra and inter-day precision were obtained (RSDs≤7.06% and RSD≤7.11%, respectively). The method was successfully applied to wastewater samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of metabolite of nicergoline in human plasma by high-performance liquid chromatography and its application in pharmacokinetic studies.

PubMed

Zheng, Rong; Wu, Yi-Hong; Jiang, De-Xi; Zhang, Dan

2012-02-01

A fast, simple and sensitive high performance liquid chromatographic (HPLC) method has been developed for determination of 10 α -methoxy-6-methyl ergoline-8 β -methanol (MDL, a main metabolite of nicergoline) in human plasma. One-step liquid-liquid extraction (LLE) with diethyl ether was employed as the sample preparation method. Tizanidine hydrochloride was selected as the internal standard (IS). Analysis was carried out on a Diamonsil ODS column (150 mm×4.6 mm, 5 μm) using acetonitrile-ammonium acetate (0.1 mol/L) (15/85, v/v) as mobile phase at detection wavelength of 224 nm. The calibration curves were linear over the range of 2.288-73.2 ng/mL with a lower limit of quantitation (LLOQ) of 2.288 ng/mL. The intra- and inter-day precision values were below 13% and the recoveries were from 74.47% to 83.20% at three quality control levels. The method herein described was successfully applied in a randomized crossover bioequivalence study of two different nicergoline preparations after administration of 30 mg in 20 healthy volunteers.

Determination of metabolite of nicergoline in human plasma by high-performance liquid chromatography and its application in pharmacokinetic studies

PubMed Central

Zheng, Rong; Wu, Yi-Hong; Jiang, De-Xi; Zhang, Dan

2012-01-01

A fast, simple and sensitive high performance liquid chromatographic (HPLC) method has been developed for determination of 10α-methoxy-6-methyl ergoline-8β-methanol (MDL, a main metabolite of nicergoline) in human plasma. One-step liquid–liquid extraction (LLE) with diethyl ether was employed as the sample preparation method. Tizanidine hydrochloride was selected as the internal standard (IS). Analysis was carried out on a Diamonsil ODS column (150 mm×4.6 mm, 5 μm) using acetonitrile–ammonium acetate (0.1 mol/L) (15/85, v/v) as mobile phase at detection wavelength of 224 nm. The calibration curves were linear over the range of 2.288–73.2 ng/mL with a lower limit of quantitation (LLOQ) of 2.288 ng/mL. The intra- and inter-day precision values were below 13% and the recoveries were from 74.47% to 83.20% at three quality control levels. The method herein described was successfully applied in a randomized crossover bioequivalence study of two different nicergoline preparations after administration of 30 mg in 20 healthy volunteers. PMID:29403722

Tutorial on Biostatistics: Linear Regression Analysis of Continuous Correlated Eye Data

PubMed Central

Ying, Gui-shuang; Maguire, Maureen G; Glynn, Robert; Rosner, Bernard

2017-01-01

Purpose To describe and demonstrate appropriate linear regression methods for analyzing correlated continuous eye data. Methods We describe several approaches to regression analysis involving both eyes, including mixed effects and marginal models under various covariance structures to account for inter-eye correlation. We demonstrate, with SAS statistical software, applications in a study comparing baseline refractive error between one eye with choroidal neovascularization (CNV) and the unaffected fellow eye, and in a study determining factors associated with visual field data in the elderly. Results When refractive error from both eyes were analyzed with standard linear regression without accounting for inter-eye correlation (adjusting for demographic and ocular covariates), the difference between eyes with CNV and fellow eyes was 0.15 diopters (D; 95% confidence interval, CI −0.03 to 0.32D, P=0.10). Using a mixed effects model or a marginal model, the estimated difference was the same but with narrower 95% CI (0.01 to 0.28D, P=0.03). Standard regression for visual field data from both eyes provided biased estimates of standard error (generally underestimated) and smaller P-values, while analysis of the worse eye provided larger P-values than mixed effects models and marginal models. Conclusion In research involving both eyes, ignoring inter-eye correlation can lead to invalid inferences. Analysis using only right or left eyes is valid, but decreases power. Worse-eye analysis can provide less power and biased estimates of effect. Mixed effects or marginal models using the eye as the unit of analysis should be used to appropriately account for inter-eye correlation and maximize power and precision. PMID:28102741

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

PubMed

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

2014-08-01

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

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

PubMed

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

2014-04-01

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

Grassroots inter-professional networks: the case of organizing care for older cancer patients.

PubMed

Bagayogo, Fatou Farima; Lepage, Annick; Denis, Jean-Louis; Lamothe, Lise; Lapointe, Liette; Vedel, Isabelle

2016-09-19

Purpose The purpose of this paper of inter-professional networks is to analyze the evolution of relationships between professional groups enacting new forms of collaboration to address clinical imperatives. Design/methodology/approach This paper uses a case study based on semi-structured interviews with physicians and nurses, document analysis and informal discussions. Findings This study documents how two inter-professional networks were developed through professional agency. The findings show that the means by which networks are developed influence the form of collaboration therein. One of the networks developed from day-to-day, immediately relevant, exchange, for patient care. The other one developed from more formal and infrequent research and training exchanges that were seen as less decisive in facilitating patient care. The latter resulted in a loosely knit network based on a small number of ad hoc referrals while the other resulted in a tightly knit network based on frequent referrals and advice seeking. Practical implications Developing inter-professional networks likely require a sustained phase of interpersonal contacts characterized by persuasion, knowledge sharing, skill demonstration and trust building from less powerful professional groups to obtain buy-in from more powerful professional groups. The nature of the collaboration in any resulting network depends largely on the nature of these initial contacts. Originality/value The literature on inter-professional healthcare networks focusses on mandated networks such as NHS managed care networks. There is a lack of research on inter-professional networks that emerged from the bottom up at the initiative of healthcare professionals in response to clinical imperatives. This study looks at some forms of collaboration that these "grass-root" initiatives engender and how they are consolidated.

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

PubMed

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

2014-03-01

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

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

NASA Astrophysics Data System (ADS)

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

2015-07-01

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

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

PubMed

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

2017-12-15

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

Reliable and fast volumetry of the lumbar spinal cord using cord image analyser (Cordial).

PubMed

Tsagkas, Charidimos; Altermatt, Anna; Bonati, Ulrike; Pezold, Simon; Reinhard, Julia; Amann, Michael; Cattin, Philippe; Wuerfel, Jens; Fischer, Dirk; Parmar, Katrin; Fischmann, Arne

2018-04-30

To validate the precision and accuracy of the semi-automated cord image analyser (Cordial) for lumbar spinal cord (SC) volumetry in 3D T1w MRI data of healthy controls (HC). 40 3D T1w images of 10 HC (w/m: 6/4; age range: 18-41 years) were acquired at one 3T-scanner in two MRI sessions (time interval 14.9±6.1 days). Each subject was scanned twice per session, allowing determination of test-retest reliability both in back-to-back (intra-session) and scan-rescan images (inter-session). Cordial was applied for lumbar cord segmentation twice per image by two raters, allowing for assessment of intra- and inter-rater reliability, and compared to a manual gold standard. While manually segmented volumes were larger (mean: 2028±245 mm 3 vs. Cordial: 1636±300 mm 3 , p<0.001), accuracy assessments between manually and semi-automatically segmented images showed a mean Dice-coefficient of 0.88±0.05. Calculation of within-subject coefficients of variation (COV) demonstrated high intra-session (1.22-1.86%), inter-session (1.26-1.84%), as well as intra-rater (1.73-1.83%) reproducibility. No significant difference was shown between intra- and inter-session reproducibility or between intra-rater reliabilities. Although inter-rater reproducibility (COV: 2.87%) was slightly lower compared to all other reproducibility measures, between rater consistency was very strong (intraclass correlation coefficient: 0.974). While under-estimating the lumbar SCV, Cordial still provides excellent inter- and intra-session reproducibility showing high potential for application in longitudinal trials. • Lumbar spinal cord segmentation using the semi-automated cord image analyser (Cordial) is feasible. • Lumbar spinal cord is 40-mm cord segment 60 mm above conus medullaris. • Cordial provides excellent inter- and intra-session reproducibility in lumbar spinal cord region. • Cordial shows high potential for application in longitudinal trials.

Precision of FLEET Velocimetry Using High-Speed CMOS Camera Systems

NASA Technical Reports Server (NTRS)

Peters, Christopher J.; Danehy, Paul M.; Bathel, Brett F.; Jiang, Naibo; Calvert, Nathan D.; Miles, Richard B.

2015-01-01

Femtosecond laser electronic excitation tagging (FLEET) is an optical measurement technique that permits quantitative velocimetry of unseeded air or nitrogen using a single laser and a single camera. In this paper, we seek to determine the fundamental precision of the FLEET technique using high-speed complementary metal-oxide semiconductor (CMOS) cameras. Also, we compare the performance of several different high-speed CMOS camera systems for acquiring FLEET velocimetry data in air and nitrogen free-jet flows. The precision was defined as the standard deviation of a set of several hundred single-shot velocity measurements. Methods of enhancing the precision of the measurement were explored such as digital binning (similar in concept to on-sensor binning, but done in post-processing), row-wise digital binning of the signal in adjacent pixels and increasing the time delay between successive exposures. These techniques generally improved precision; however, binning provided the greatest improvement to the un-intensified camera systems which had low signal-to-noise ratio. When binning row-wise by 8 pixels (about the thickness of the tagged region) and using an inter-frame delay of 65 microseconds, precisions of 0.5 meters per second in air and 0.2 meters per second in nitrogen were achieved. The camera comparison included a pco.dimax HD, a LaVision Imager scientific CMOS (sCMOS) and a Photron FASTCAM SA-X2, along with a two-stage LaVision HighSpeed IRO intensifier. Excluding the LaVision Imager sCMOS, the cameras were tested with and without intensification and with both short and long inter-frame delays. Use of intensification and longer inter-frame delay generally improved precision. Overall, the Photron FASTCAM SA-X2 exhibited the best performance in terms of greatest precision and highest signal-to-noise ratio primarily because it had the largest pixels.

Basic Evaluation of the Newly Developed "Lias Auto P-FDP" Assay and the Influence of Plasmin-α2 Plasmin Inhibitor Complex Values on Discrepancy in the Comparison with "Lias Auto D-Dimer Neo" Assay.

PubMed

Kumano, Osamu; Ieko, Masahiro; Komiyama, Yutaka; Naito, Sumiyoshi; Yoshida, Mika; Takahashi, Nobuhiko; Ohmura, Kazumasa; Hayasaki, Junki; Hayakawa, Mineji

2018-04-01

Laboratory determination of fibrin/fibrinogen degradation products (FDP) levels, along with that of the D-dimer, is important for assessing the fibrinolytic situation. Recently, we developed a new FDP reagent "Lias Auto P-FDP", which can detect various FDP fragments. The purpose of this study was to evaluate the basic performance of the newly developed Lias Auto P-FDP and compare it with Lias Auto D-Dimer Neo assay. The within-run precision of Lias Auto P-FDP and Lias Auto D-Dimer was determined 20 times in low and high value controls. The between-day precision was evaluated five times a day for five days. The linearity study was performed by diluting high value samples for 2 - 10-fold and 2 - 8-fold. The comparative study was performed using 172 patient samples with elevated FDP values. For the discrepancy analysis, the samples were divided into three groups by the discrepancy percentage between the FDP and D-dimer values. The groups were defined as follows: lower discrepancy group, less than -20%; no discrepancy group, -20% to 20%; upper discrepancy group, more than 20%. The coefficient of variation % (CV%) in within-run and between-day precision were within 3.8% for both FDP and the D-dimer. The correlation coefficients were more than 0.999 and the linearity was high. In the comparative study, the values of FDP were higher than that of the D-dimer in all samples. The median FDP and D-dimer values of lower discrepancy, no discrepancy, and upper discrepancy groups were 11.8, 20.3, and 51.4, and 8.0, 11.3, and 13.1, respectively. FDP showed an increasing tendency but D-Dimer showed constant values. Thus, the possible cause of discrepancy between FDP and D-dimer values were the elevated FDP values. In addition, the values of plasmin-α2 plasmin inhibitor complex (PIC) in the upper discrepancy group were higher than that of the lower and no discrepancy groups, indicating progression of fibrinolysis. In this study, we evaluated the newly developed Lias Auto P-FDP reagent and confirmed that the basic performance was acceptable. FDP was elevated in samples with high PIC values, which indicated progression of fibrinolysis. Determination of fibrinolysis conditions by FDP measurement is important.

A method for determination of [Fe3+]/[Fe2+] ratio in superparamagnetic iron oxide

NASA Astrophysics Data System (ADS)

Jiang, Changzhao; Yang, Siyu; Gan, Neng; Pan, Hongchun; Liu, Hong

2017-10-01

Superparamagnetic iron oxide nanoparticles (SPION), as a kind of nanophase materials, are widely used in biomedical application, such as magnetic resonance imaging (MRI), drug delivery, and magnetic field assisted therapy. The magnetic property of SPION has close connection with its crystal structure, namely it is related to the ratio of Fe3+ and Fe2+ which form the SPION. So a simple way to determine the content of the Fe3+ and Fe2+ is important for researching the property of SPION. This review covers a method for determination of the Fe3+ and Fe2+ ratio in SPION by UV-vis spectrophotometry based the reaction of Fe2+ and 1,10-phenanthroline. The standard curve of Fe with R2 = 0.9999 is used for determination the content of Fe2+ and total iron with 2.5 mL 0.01% (w/v) SPION digested by HCl, pH = 4.30 HOAc-NaAc buffer 10 mL, 0.01% (w/v) 1,10-phenanthroline 5 mL and 10% (w/v) ascorbic acid 1 mL for total iron determine independently. But the presence of Fe3+ interfere with obtaining the actual value of Fe2+ (the error close to 9%). We designed a calibration curve to eliminate the error by devising a series of solution of different ratio of [Fe3+]/[Fe2+], and obtain the calibration curve. Through the calibration curve, the error between the measured value and the actual value can be reduced to 0.4%. The R2 of linearity of the method is 0.99441 and 0.99929 for Fe2+ and total iron respectively. The error of accuracy of recovery and precision of inter-day and intra-day are both lower than 2%, which can prove the reliability of the determination method.

Simplified miniaturized ultrasound-assisted matrix solid phase dispersion extraction and high performance liquid chromatographic determination of seven flavonoids in citrus fruit juice and human fluid samples: hesperetin and naringenin as biomarkers.

PubMed

Barfi, Behruz; Asghari, Alireza; Rajabi, Maryam; Barfi, Azadeh; Saeidi, Iman

2013-10-11

In the present study, for the first time, a simplified miniaturized ultrasound-assisted matrix solid-phase dispersion (SM-USA-MSPD) method with a different application for liquid matrices was developed to extract different flavonoids (hesperidin, diosmin, eriocitrin, narirutin, naringin, hesperetin and naringenin) from citrus fruit juice and human fluid samples prior to their determination using high performance liquid chromatography (HPLC). Different effective parameters were studied and under the optimum conditions (including sample volume: 150μL; solid phase: silica-based C18, 200mg; eluting solvent: methanol, 500μL; pH: 4; and sonication: 6min; at room temperature), limits of detection and limits of quantification were ranged from 23.3 to 46.8ngmL(-1) and 74.8 to 141.5ngmL(-1), respectively. Once optimized, analytical performance of the method was studied in terms of linearity (0.074-198.5μgmL(-1), r(2)>0.991), accuracy (recovery=84.6-101.5%), and precision (repeatability: intra-day precision<5.9%, and inter-day precision<7.2%). At the end, SM-USA-MSPD method was successfully applied to estimate the levels of hesperetin and naringenin in plasma and urinary excretion -after ingestion of orange, grapefruit and lime juices- and the obtained results confirmed that these compounds could be used as good biomarkers of citrus fruit juice intake. Copyright © 2013 Elsevier B.V. All rights reserved.

Assessment of metabolic phenotypic variability in children’s urine using 1H NMR spectroscopy

NASA Astrophysics Data System (ADS)

Maitre, Léa; Lau, Chung-Ho E.; Vizcaino, Esther; Robinson, Oliver; Casas, Maribel; Siskos, Alexandros P.; Want, Elizabeth J.; Athersuch, Toby; Slama, Remy; Vrijheid, Martine; Keun, Hector C.; Coen, Muireann

2017-04-01

The application of metabolic phenotyping in clinical and epidemiological studies is limited by a poor understanding of inter-individual, intra-individual and temporal variability in metabolic phenotypes. Using 1H NMR spectroscopy we characterised short-term variability in urinary metabolites measured from 20 children aged 8-9 years old. Daily spot morning, night-time and pooled (50:50 morning and night-time) urine samples across six days (18 samples per child) were analysed, and 44 metabolites quantified. Intraclass correlation coefficients (ICC) and mixed effect models were applied to assess the reproducibility and biological variance of metabolic phenotypes. Excellent analytical reproducibility and precision was demonstrated for the 1H NMR spectroscopic platform (median CV 7.2%). Pooled samples captured the best inter-individual variability with an ICC of 0.40 (median). Trimethylamine, N-acetyl neuraminic acid, 3-hydroxyisobutyrate, 3-hydroxybutyrate/3-aminoisobutyrate, tyrosine, valine and 3-hydroxyisovalerate exhibited the highest stability with over 50% of variance specific to the child. The pooled sample was shown to capture the most inter-individual variance in the metabolic phenotype, which is of importance for molecular epidemiology study design. A substantial proportion of the variation in the urinary metabolome of children is specific to the individual, underlining the potential of such data to inform clinical and exposome studies conducted early in life.

A bioanalytical HPLC method for coumestrol quantification in skin permeation tests followed by UPLC-QTOF/HDMS stability-indicating method for identification of degradation products.

PubMed

Bianchi, Sara E; Teixeira, Helder F; Kaiser, Samuel; Ortega, George G; Schneider, Paulo Henrique; Bassani, Valquiria L

2016-05-01

Coumestrol is present in several species of the Fabaceae family widely distributed in plants. The estrogenic and antioxidant activities of this molecule show its potential as skin anti-aging agent. These characteristics reveal the interest in developing analytical methodology for permeation studies, as well as to know the stability of coumestrol identifying the major degradation products. Thus, the present study was designed, first, to develop and validate a versatile liquid chromatography (HPLC) method to quantify coumestrol in a hydrogel formulation in different porcine skin layers (stratum corneum, epidermis, and dermis) in permeation tests. In the stability-indicating test coumestrol samples were exposed to stress conditions: temperature, UVC light, oxidative, acid and alkaline media. The degradation products, as well as the constituents extracted from the hydrogel, adhesive tape or skin were not eluted in the retention time of the coumestrol. Hence, the HPLC method showed to be versatile, specific, accurate, precise and robust showing excellent performance for quantifying coumestrol in complex matrices involving skin permeation studies. Coumestrol recovery from porcine ear skin was found to be in the range of 97.07-107.28 μg/mL; the intra-day precision (repeatability) and intermediate precision (inter-day precision), respectively lower than 4.71% and 2.09%. The analysis using ultra-performance liquid chromatography coupled to a quadrupole time-of-flight high definition mass spectrometry detector (UPLC-QTOF/HDMS) suggest the MS fragmentation patterns and the chemical structure of the main degradation products. These results represent new and relevant findings for the development of coumestrol pharmaceutical and cosmetic products. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of an isocratic HPLC method for catechin quantification and its application to formulation studies.

PubMed

Li, Danhui; Martini, Nataly; Wu, Zimei; Wen, Jingyuan

2012-10-01

The aim of this study was to develop a simple, rapid and accurate isocratic HPLC analytical method to qualify and quantify five catechin derivatives, namely (+)-catechin (C), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)-epicatechin (EC) and (-)-epigallocatechin gallate (EGCG). To validate the analytical method, linearity, repeatability, intermediate precision, sensitivity, selectivity and recovery were investigated. The five catechin derivatives were completely separated by HPLC using a mobile phase containing 0.1% TFA in Milli-Q water (pH 2.0) mixed with methanol at the volume ratio of 75:25 at a flow rate of 0.8 ml/min. The method was shown to be linear (r²>0.99), repeatable with instrumental precision<2.0 and intra-assay precision<2.5 (%CV, percent coefficient of variation), precise with intra-day variation<1 and inter-day variation<2.5 (%CV, percent coefficient of variation) and sensitive (LOD<1 μg/mL and LOQ<3 μg/mL) over the calibration range for all five derivatives. Derivatives could be fully recovered in the presence of niosomal formulation (recovery rates>91%). Selectivity of the method was proven by the forced degradation studies, which showed that under acidic, basic, oxidation temperature and photolysis stresses, the parent drug can be separated from the degradation products by means of this analytical method. The described method was successfully applied in the in vitro release studies of catechin-loaded niosomes to manifest its utility in formulation characterization. Obtained results indicated that the drug release from niosomal formulations was a biphasic process and a diffusion mechanism regulated the permeation of catechin niosomes. Copyright © 2012 Elsevier B.V. All rights reserved.

Inter-monitor standard calibration and tests for Ar-Ar biases

NASA Astrophysics Data System (ADS)

Hemming, S. R.; Turrin, B. D.; Swisher, C. C.; Cox, S. E.; Mesko, G. T.; Chang, S.

2010-12-01

A major issue facing the geochronology community is that there are biases between chronometers that have become significant as we interrogate the rock record with ever increasing levels of precision. Despite much progress there are still major issues with building a timescale with multiple chronometers and for testing synchroneity of anomalous events in Earth history. Improvements in methods for determining U-Pb zircon dates has led to their application at precisions of 0.2% or better in rocks even younger than a million years (e.g., Crowley et al., 2007, Geology), and significantly better than 0.1% in some cases (e.g., Bowring et al., 2006, Paleontological Society Papers, Volume 12). Additionally, the inter-calibration experiments for U-Pb using the EARTHTIME tracer have yielded excellent agreement among labs (0.05%) and these values are traceable back to SI units through the EARTHTIME tracer calibration experiment (e.g., Condon et al., in press, Geochimica et Cosmochimica Acta). These advances have greatly extended the need for cross calibrations of the two chronometers and ultimately seamless integration into the Geologic Time Scale. The direct comparison of ages using different chronometers and laboratories is the central aspect in the quest for a highly resolved and accurate time scale of Earth History. A significant obstacle to high precision inter-comparison of U-Pb and Ar-Ar age results is the current inability of Ar-Ar labs to achieve agreement on monitor standard ages at the 0.1% level. At the heart of Ar-Ar geochronology is the assumption of a known absolute age of a standard, to which all applicable unknowns are referenced. While individual labs are able to achieve highly precise apparent ages on monitor standards, the lack of a “gold standard” for Ar-Ar dating means that we do not know who is, or indeed if anybody is correct. In order to improve our understanding of factors that may lead to biases in our own laboratories at Lamont-Doherty Earth Observatory (AGES) and at Rutgers University, we have begun a concerted effort to test various factors that could lead to biases. AGES uses analogue multiplier peak hopping measurements on a Micromass VG 5400 noble gas mass spectrometer. Rutgers uses ion counting on a MAP 215-50 noble gas mass spectrometer, modified to collect Ar-36 by ion counting and Ar-40 by faraday simultaneously. We will present the results of our internal inter-comparison of monitor standards from each laboratory and will compare them to published results for these standards. We will also present our results from analyzing different sized samples of Fish Canyon sanidine, Alder Creek sanidine, and McClure Mountain hornblende monitor standards.

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.

Evaluation and comparison of Abbott Jaffe and enzymatic creatinine methods: Could the old method meet the new requirements?

PubMed

Küme, Tuncay; Sağlam, Barıs; Ergon, Cem; Sisman, Ali Rıza

2018-01-01

The aim of this study is to evaluate and compare the analytical performance characteristics of the two creatinine methods based on the Jaffe and enzymatic methods. Two original creatinine methods, Jaffe and enzymatic, were evaluated on Architect c16000 automated analyzer via limit of detection (LOD) and limit of quantitation (LOQ), linearity, intra-assay and inter-assay precision, and comparability in serum and urine samples. The method comparison and bias estimation using patient samples according to CLSI guideline were performed on 230 serum and 141 urine samples by analyzing on the same auto-analyzer. The LODs were determined as 0.1 mg/dL for both serum methods and as 0.25 and 0.07 mg/dL for the Jaffe and the enzymatic urine method respectively. The LOQs were similar with 0.05 mg/dL value for both serum methods, and enzymatic urine method had a lower LOQ than Jaffe urine method, values at 0.5 and 2 mg/dL respectively. Both methods were linear up to 65 mg/dL for serum and 260 mg/dL for urine. The intra-assay and inter-assay precision data were under desirable levels in both methods. The higher correlations were determined between two methods in serum and urine (r=.9994, r=.9998 respectively). On the other hand, Jaffe method gave the higher creatinine results than enzymatic method, especially at the low concentrations in both serum and urine. Both Jaffe and enzymatic methods were found to meet the analytical performance requirements in routine use. However, enzymatic method was found to have better performance in low creatinine levels. © 2017 Wiley Periodicals, Inc.

Characterization and application of restricted access carbon nanotubes in online extraction of anticonvulsant drugs from plasma samples followed by liquid chromatography analysis.

PubMed

Dos Santos, Rodrigo Campos; Kakazu, Adriana Kaori; Santos, Mariane Gonçalves; Belinelli Silva, Fábio Antônio; Figueiredo, Eduardo Costa

2017-06-01

Anticonvulsant drugs are often used in the treatment of epilepsy. However, their therapeutic monitoring is often necessary in order to obtain an appropriate dose adjustment, due to the proximity between their therapeutic and toxic ranges. The aim of this study was to carry out the synthesis, characterization and use of restricted access carbon nanotubes (RACNTs) in an online method for the analyses of phenobarbital and carbamazepine and primidone from untreated human blood plasma by column switching liquid chromatography. Therefore, the synthesis of RACNTs was carried out through coating commercial Carbon nanotubes with bovine serum albumin (BSA) to subsequently use them as adsorbents in a column switching system operating in the backflush mode. This material was evaluated through the construction of the kinetic and isotherm curves. The experimental data for the interaction of primidone with RACNTs were adequately adjusted to the chemisorption and Sips models for the kinetic and adsorption studies, respectively. The analytical curves ranged from 2.0 to 40.0mgL -1 , with correlation coefficients higher than 0.99, for all the analytes. The LODs of 0.1, 0.1 and 0.01μgmL -1 were defined for PHB, PRM and CBZ, respectively. The relative standard deviation values ranged from 1.0% to 8.4% for the intra assay precision and from 2.7% to 7.6% for inter assay precision. The relative error values ranged from -13.4% to 7.7% for the intra assay accuracy and from -8.6% to 2.5% for the inter assay accuracy. The method was adequately used in the therapeutic monitoring of anticonvulsant drugs in human plasma samples. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed

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

2016-11-01

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

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

PubMed Central

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

2015-01-01

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

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

PubMed

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

2018-08-03

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

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

Determination of three steroidal saponins from Ophiopogon japonicus (Liliaceae) via high-performance liquid chromatography with mass spectrometry.

PubMed

Wang, Yongyi; Xu, Jinzhong; Qu, Haibin

2013-01-01

A simple and accurate analytical method was developed for simultaneous quantification of three steroidal saponins in the roots of Ophiopogon japonicus via high-performance liquid chromatography (HPLC) with mass spectrometry (MS) in this study. Separation was performed on a Tigerkin C(18) column and detection was performed by mass spectrometry. A mobile phase consisted of 0.02% formic acid in water (v/v) and 0.02% formic acid in acetonitrile (v/v) was used with a flow rate of 0.5 mL min(-1). The quantitative HPLC-MS method was validated for linearity, precision, repeatability, stability, recovery, limits of detection and quantification. This developed method provides good linearity (r >0.9993), intra- and inter-day precisions (RSD <4.18%), repeatability (RSD <5.05%), stability (RSD <2.08%) and recovery (93.82-102.84%) for three steroidal saponins. It could be considered as a suitable quality control method for O. japonicus.

Determination of rifampicin in human plasma by high-performance liquid chromatography coupled with ultraviolet detection after automatized solid-liquid extraction.

PubMed

Louveau, B; Fernandez, C; Zahr, N; Sauvageon-Martre, H; Maslanka, P; Faure, P; Mourah, S; Goldwirt, L

2016-12-01

A precise and accurate high-performance liquid chromatography (HPLC) quantification method of rifampicin in human plasma was developed and validated using ultraviolet detection after an automatized solid-phase extraction. The method was validated with respect to selectivity, extraction recovery, linearity, intra- and inter-day precision, accuracy, lower limit of quantification and stability. Chromatographic separation was performed on a Chromolith RP 8 column using a mixture of 0.05 m acetate buffer pH 5.7-acetonitrile (35:65, v/v) as mobile phase. The compounds were detected at a wavelength of 335 nm with a lower limit of quantification of 0.05 mg/L in human plasma. Retention times for rifampicin and 6,7-dimethyl-2,3-di(2-pyridyl) quinoxaline used as internal standard were respectively 3.77 and 4.81 min. This robust and exact method was successfully applied in routine for therapeutic drug monitoring in patients treated with rifampicin. Copyright © 2016 John Wiley & Sons, Ltd.

Inflow-vascular space occupancy (iVASO) reproducibility in the hippocampus and cortex at different blood water nulling times.

PubMed

Rane, Swati; Talati, Pratik; Donahue, Manus J; Heckers, Stephan

2016-06-01

Inflow-vascular space occupancy (iVASO) measures arterial cerebral blood volume (aCBV) using accurate blood water nulling (inversion time [TI]) when arterial blood reaches the capillary, i.e., at the arterial arrival time. This work assessed the reproducibility of iVASO measurements in the hippocampus and cortex at multiple TIs. The iVASO approach was implemented at multiple TIs in 10 healthy volunteers at 3 Tesla. aCBV values were measured at each TI in the left and right hippocampus, and the cortex. Reproducibility of aCBV measurements within scans (same day) and across sessions (different days) was assessed using the intraclass correlation coefficient (ICC). Overall hippocampal aCBV was significantly higher than cortical aCBV, likely due to higher gray matter volume. Hippocampal ICC values were high at short TIs (≤914 ms; intrascan values = 0.80-0.96, interscan values = 0.61-0.91). Cortically, high ICC values were observed at intermediate TIs of 914 (intra: 0.93, inter: 0.87) and 1034 ms (intra: 0.96, inter: 0.86). The ICC values were comparable to established contrast-based CBV measures. iVASO measurements are reproducible within and across sessions. TIs for iVASO measurements should be chosen carefully, taking into account heterogeneous arterial arrival times in different brain regions. Magn Reson Med 75:2379-2387, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

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.

Precise measurements of energy loss straggling for swift heavy ions in polymers

NASA Astrophysics Data System (ADS)

Rani, Bindu; Neetu; Sharma, Kalpana; Diwan, P. K.; Kumar, Shyam

2016-11-01

The energy loss straggling measurements for heavy ions with Z = 3-22 (∼0.2-2.5 MeV/u) in PEN (C7H5O2) and PET (C10H8O4) polymers have been carried out utilizing the swift heavy ion beam facility from 15UD Pelletron accelerator at Inter University Accelerator Centre (IUAC), New Delhi, India. The recorded spectra are analyzed in such a way that the Straggling associated with energy loss process could be measured in a systematic manner at any selected value of energy, in terms of per unit thickness of the absorber, at any desired energy intervals. The measured values have been compared with the calculated values obtained from the most commonly used Bethe-Livingston formulations applicable for collisional straggling. The results are tried to be understood in terms of the effective charge on the impinging ion within the absorber. Some interesting trends are observed.

Inter-Diffusion in the Presence of Free Convection

NASA Technical Reports Server (NTRS)

Gupta, Prabhat K.

1999-01-01

Because of their technological importance, establishment of the precise values of interdiffusion coefficients is important in multicomponent fluid systems. Such values are not available because diffusion is influenced by free convection due to compositionally induced density variations. In this project, earth based diffusion experiments are being performed in a viscous fluid system PbO-SiO2 at temperatures between 500-1000 C. This system is chosen because it shows a large variation in density with small changes in composition and is expected to show a large free convection effect. Infinite diffusion couples at different temperatures and times are being studied with different orientations with respect to gravity. Composition fields will be measured using an Electron Microprobe Analyzer and will be compared with the results of a complementary modeling study to extract the values of the true diffusion coefficient from the measured diffusion profiles.

The Role of the Atrial Electromechanical Delay in Predicting Atrial Fibrillation in Myotonic Dystrophy Type 1 Patients.

PubMed

Russo, Vincenzo; Rago, Anna; Ciardiello, Carmine; Russo, Maria Giovanna; Calabrò, Paolo; Politano, Luisa; Nigro, Gerardo

2016-01-01

Paroxysmal atrial tachyarrhythmias frequently occur in myotonic dystrophy type 1 (DM1) patients. The aim of the current study was to evaluate the atrial electromechanical-delay (AEMD) in a DM1-population with normal cardiac function and its relationship to atrial fibrillation (AF) onset. Fifty DM1 patients (28 male; mean age 34.2 ± 11.4 years) and 50 healthy subjects used as controls, matched for age and gender, were studied for the occurrence of atrial fibrillation during a 4-year follow-up, through 30-day external loop recorder (ELR) monitoring performed every 6 months. Intra-AEMD and inter-AEMD of both atrium were measured through tissue-Doppler echocardiography. Compared to the healthy control group, the DM1 group showed a statistically significant increase in inter-AEMD and intraleft-AEMD. Dividing the DM1-group into 2 subgroups (patients with or without AF), the inter-AEMD and intraleft-AEMD were significantly higher in the subgroup with AF compared to the subgroup without AF. A cut off value of 39.2 milliseconds for intraleft-AEMD had a sensitivity of 90% and a specificity of 90% in identifying DM1 patients with AF risk. A cut off value of 57.7 milliseconds for inter-AEMD had a sensitivity of 84.2% and a specificity of 93.5% in identifying this category of patients. Our results showed that the echocardiographic atrial electromechanical delay indices (intraleft and inter-AEMD) were significantly increased in DM1 subjects with normal cardiac function. Intraleft and inter-AEMD represent noninvasive, inexpensive, useful and simple parameters to assess the AF risk in DM1 patients. © 2015 Wiley Periodicals, Inc.

Intra- and inter-observer agreement when using a descriptive classification scale for clinical assessment of faecal consistency in growing pigs.

PubMed

Pedersen, Ken Steen; Toft, Nils

2011-03-01

The objective of the current study was to evaluate intra- and inter-observer agreement using a descriptive classification scale with four categories, descriptive text and pictures for assessment of consistency in faecal samples from pigs post weaning. The four consistency categories were score one=firm and shaped, score two=soft and shaped, score three=loose and score four=watery. Five observers from the same veterinary practice examined 100 faecal samples using the scale with four categories. Four of the observers examined the 100 faecal samples twice within the same day. Within observers the difference in proportions for the individual consistency categories between two examinations was on average 0.04 (range: 0-0.10). The mean intra-observer agreement was 0.82 (range: 0.72-0.91) with a mean kappa value of 0.76 (range: 0.61-0.88). For inter-observer agreement overall kappa was 0.64. For the 10 pair-wise comparisons the mean inter-observer agreement was 0.73 (range: 0.61-0.90) with a mean kappa value of 0.64 (range: 0.48-0.87). The difference in proportions for the individual consistency categories was on average 0.08 (range: 0-0.17). In conclusion, the agreement observed for the descriptive classification scale with four categories, descriptive text and pictures may be categorized as a substantial to almost perfect intra-observer agreement and a moderate to almost perfect inter-observer agreement. However, more objective measures than clinical scales may still be needed to improve intra- and inter-observer agreement in research studies. Copyright © 2010 Elsevier B.V. All rights reserved.

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

Determination of rhynchophylline and hirsutine in rat plasma by UPLC-MS/MS after oral administration of Uncaria rhynchophylla extract.

PubMed

Wu, Yu-Tse; Lin, Lie-Chwen; Tsai, Tung-Hu

2014-03-01

An ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to concurrently determine rhynchophylline and hirsutine in rat plasma. The sample preparation of rat plasma was achieved by alkalization and liquid-liquid extraction. The mass transition of precursor ion → product ion pairs were monitored at m/z 385.2 → 160.0 for rhynchophylline, m/z 369.3 → 144.0 for hirsutine and m/z 414.0 → 220.0 for noscapine (internal standard). This method revealed linear relationships from 2.5 to 50 ng/mL (r(2)  > 0.997) for rhynchophylline and from 2.5 to 50 ng/mL (r(2)  > 0.998) for hirsutine. The limit of quantification values for rhynchophylline and hirsutine in rat plasma were both 2.5 ng/mL. Intra-day and inter-day precisions were within 10.6% and 12.5%, respectively, for rhynchophylline and hirsutine, and the accuracy (bias) was <10%. Liquid-liquid extraction of rat plasma samples resulted in insignificant matrix effect, and the extraction recoveries were >83.6% for rhynchophylline, 73.4% for hirsutine and 90.7% for the internal standard. This method was applied successfully to a pharmacokinetic study of rhynchophylline and hirsutine in rats after oral administration. Copyright © 2013 John Wiley & Sons, Ltd.

National Survey on Internal Quality Control for HbA(1c) Analytical Instruments in 331 Hospital Laboratories of China.

PubMed

Zeng, Rong; Wang, Wei; Zhao, Haijian; Fei, Yang; Wang, Zhiguo

2015-01-01

The narrow gap of HbA1 value of mass fraction between "normal" (< 6.0%) and "diabetes" (≥ 6.5%) necessitates tight control of inter-assay standardization, assay precision, and trueness. This survey was initiated to obtain knowledge of the current situation of internal quality control (IQC) practice for HbA(1c) in China and find out the most appropriate quality specifications. Data of IQC for HbA(1c) in 331 institutions participating in the national proficiency testing (PT) programs in China were evaluated using four levels of quality specifications, and the percentages of laboratories meeting the quality requirement were calculated to find out the most appropriate quality specifications for control materials of HbA(1c) in China. The IQC data varied vastly among 331 clinical laboratories in China. The measurement of control materials covered a wide range from 4.52% to 12.24% (inter-quartile range) and there were significant differences among the CVs of different methods, including LPLC, CE-HPLC, AC-HPLC, immunoturbidimetry, and others. Among the four main methods, CE-HPLC and AC-HPLC achieved a better precision. As we can see, the performance of laboratories for HbA(1c) has yet to be improved. Clinical laboratories in China should improve their performance with a stricter imprecision criteria.

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

PubMed

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

2010-05-28

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

Precision of the upgraded cottonscan instrument for measuring the average fiber linear density (fineness) of cotton lint samples

USDA-ARS?s Scientific Manuscript database

An inter-laboratory trial was conducted to validate the operation of the CottonscanTM technology as useful technique for determining the average fiber linear density of cotton. A significant inter-laboratory trial was completed and confirmed that the technology is quite acceptable. For fibers fin...

A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids.

PubMed

Zheng, Xiaojiao; Qiu, Yunping; Zhong, Wei; Baxter, Sarah; Su, Mingming; Li, Qiong; Xie, Guoxiang; Ore, Brandon M; Qiao, Shanlei; Spencer, Melanie D; Zeisel, Steven H; Zhou, Zhanxiang; Zhao, Aihua; Jia, Wei

2013-08-01

Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography mass spectrometry (GC-MS) analysis. A one-step derivatization using 100 µL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency. The best extraction efficiency of the derivatized products was achieved by a two-step extraction with hexane. The method exhibited good derivatization efficiency and recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations (RSDs) of all targeted compounds showed good intra- and inter-day (within 7 days) precision (< 10%), and good stability (< 20%) within 4 days at room temperature (23-25 °C), or 7 days when stored at -20 °C. We applied our method to measure SCFA and BCAA levels in fecal samples from rats administrated with different diet. Both univariate and multivariate statistics analysis of the concentrations of these target metabolites could differentiate three groups with ethanol intervention and different oils in diet. This method was also successfully employed to determine SCFA and BCAA in the feces, plasma and urine from normal humans, providing important baseline information of the concentrations of these metabolites. This novel metabolic profile study has great potential for translational research.

Measurement of immature platelets with Abbott CD-Sapphire and Sysmex XE-5000 in haematology and oncology patients.

PubMed

Meintker, Lisa; Haimerl, Maria; Ringwald, Jürgen; Krause, Stefan W

2013-11-01

Measurement of immature platelets was introduced into routine diagnostics by Sysmex as immature platelet fraction (IPF) some years ago and recently by Abbott as reticulated platelet fraction (rPT). Here, we compare both methods. We evaluated the precision and agreement of these parameters between Sysmex XE-5000 and Abbott CD-Sapphire in three distinct thrombocytopaenic cohorts: 30 patients with beginning thrombocytopaenia and 64 patients with recovering platelets (PLT) after chemotherapy, 16 patients with immune thrombocytopaenia (ITP) or heparin-induced thrombocytopaenia type 2 (HIT) and 110 additional normal controls. Furthermore, we analysed, how IPF/rPT differed between these thrombocytopaenic cohorts and controls. Both analysers demonstrated acceptable overall precision (repeatability) of IPF/rPT with lower precision at low PLT counts. IPF/rPT artificially increased during storage of blood samples overnight. Inter-instrument comparison showed a moderate correlation (Pearson r²=0.38) and a systematic bias of 1.04 towards higher IPF-values with the XE-5000. IPF/rPT was highest in recovering thrombopoesis after chemotherapy and moderately increased in ITP/HIT. The normal range deduced from control samples was much narrower with CD-Sapphire (1.0%-3.8%, established here for the first time) in comparison to XE-5000 (0.8%-7.9%) leading to a smaller overlap of samples with increased PLT turnover and normal controls. IPF and rPT both give useful information on PLT turnover, although the two analysers only show a moderate inter-instrument correlation and have different reference ranges. A better separation of patient groups with high PLT turnover like ITP/HIT from normal controls is obtained by CD-Sapphire.

Inter-satellite links: A versatile tool for geodesy and planetary and interplanetary navigation

NASA Astrophysics Data System (ADS)

Schlicht, Anja; Hugentobler, Urs; Hauk, Markus; Murböck, Michael; Pail, Roland

2016-07-01

With the use of low-low satellite-to-satellite tracking gravity field recovery made a big step forward. Based on this technique the Gravity Recovery And Climate Experiment (GRACE) mission delivers monthly gravity field with high precision, allowing to measure effects in Earth water storage basins and variations in ice mass in Greenland and Antarctica from space. GRACE is using a Ka-band inter-satellite ranging technique, GRACE Follow-On will in addition test optical ranging. In fundamental physics high-precision optical inter-satellite tracking will be used to detect gravitational waves in space, as a first step LISA Pathfinder was launched recently. Inter-satellite links are not only used for ranging, also data transfer in space is based on such links. ESA's European Data Relay System will be established in up-coming years to collect data from the low orbiting Sentinel satellites and transfer the high data rate to ground. The same link may be used for ranging, data transfer and time transfer, a functionality that is discussed for next generation Galileo satellites. But to exploit this synergy a common concept for all three tasks has to be developed. In this paper we show that with inter-satellite ranging techniques with µm accuracy the limited accuracy of GNSS based orbit determination of low Earth orbiters (LEO), which is due to the limitations of one-way microwave tracking (unsynchronized clocks, phase center variations and offsets of the sending and receiving antennas) can be overcome. In the ESA study GETRIS the following question is answered: How can a highly accurate and precise GEO-based two-way ranging method support GNSS tracking? The reduction of systematic errors in LEO precise orbit determination (POD) by exploiting the synergy between ranging, data- and time-transfer is assessed in a concept consisting of precise two-way GEO-LEO tracking (as used for data transfer) and an ultra-stable oscillator on-board of the geostationary satellite (GEO) synchronized from ground. We now want to get a step further and design a versatile concept for the use of this synergy in a satellite constellation based on existing and future planned ESA infrastructure and highlight the benefits in different disciplines from geodesy to interplanetary ranging, with emphasis on gravity field recovery.

Dynamic detection of non-protein-bound strychnine and brucine in rabbit muscle and synovial fluid after topical application of total Strychnos alkaloid patches.

PubMed

Tang, Huaibo; Yan, Miao; Li, Huande; Xun, Tianrong; Deng, Yang; Zhao, Yeye; Deng, Long

2014-04-01

Semen Strychni, a known toxic drug in Chinese pharmacopoeia, is notable for its therapeutic effects on local muscle and joint pain. However, oral administration can be risky. Topically administered drugs accumulate in the topical muscles and knee joints without any major increase in plasma levels; only non-protein-bound drugs in the biological fluids of target tissues are effective for therapeutic effects. A sensitive and rapid ultra performance liquid chromatography - mass spectrometry (UPLC-MS) method coupled with a microdialysis technique was developed to determine the non-protein-bound strychnine (Str) and brucine (Bru) in rabbit muscle and synovial fluid microdialysate. The UPLC separation was carried out using a 1.7μm BEH C18 column (50 mm × 2.1 mm) with a mobile phase consisting of methanol: water (29.5:70.5, v/v) with 0.1% formic acid and 20 mM ammonium acetate in water. The method was validated at concentrations ranging from 0.58 ng/ml to 467.20 ng/ml for Str and from 0.42 ng/ml to 422.40 ng/ml for Bru. Intra-day and inter-day accuracy ranged from 99.1% to 103.2% for Str and from 95.8% to 108.8% for Bru with intra-day and inter-day precision within 9.7%. The proposed method was successfully applied to determine non-protein-bound Str and Bru, and the analysates concentration remained stable in rabbit muscle and synovial fluid after topical application of total Strychnos alkaloid patches, which indicated that total Strychnos alkaloid patches could substitute for the traditional oral administration of Semen Strychni. Copyright © 2013 John Wiley & Sons, Ltd.

Magnetic solid-phase extraction and determination of puerarin in rat plasma using C(18)-functionalized magnetic silica nanoparticles by high performance liquid chromatography.

PubMed

Wang, Qi; Huang, Lijie; Yu, Panfeng; Wang, Jianchang; Shen, Shun

2013-01-01

In the paper, we presented a magnetic solid-phase extraction (MSPE) method based on C(18)-functionalized magnetic silica nanoparticles for the analysis of puerarin in rat plasma. The approach involves two steps including synthesis of magnetic solid-phase sorbents and bioanalysis. The synthesized magnetic silica microspheres modified with chloro(dimethyl)octylsilane (namely Fe(3)O(4)@SiO(2)-C(18)) can provide an efficient way for the extraction of puerarin through C(18) hydrophobic interaction. The puerarin could be easily enriched using milligram-level Fe(3)O(4)@SiO(2)-C(18) sorbents with vibration for 10min. By means of a magnet, puerarin adsorbed with Fe(3)O(4)@SiO(2)-C(18) sorbents was easily isolated from the matrix, and desorbed with CAN. No carryover was observed, and the sorbents could be recycled in our study. The method recoveries were obtained from 85.2% to 92.3%. Limits of quantification and limits of detection of 0.1μgmL(-1) and 0.05μgmL(-1), respectively were achieved. The precision was from 8.1 to 13.7% for intra-day measurement, and from 9.4 to 15.2% for inter-day variation. The accuracy ranged from 94.7 to 106.3% for intra-day measurement, and from 93.3 to 107.8% for inter-day measurement. The MSPE method was applied for analysis of puerarin in rat plasma samples. The results indicated that it was convenient and efficient for the determination of puerarin in biosamples. Copyright © 2012 Elsevier B.V. All rights reserved.

Use of magnetic effervescent tablet-assisted ionic liquid dispersive liquid-liquid microextraction to extract fungicides from environmental waters with the aid of experimental design methodology.

PubMed

Yang, Miyi; Wu, Xiaoling; Jia, Yuhan; Xi, Xuefei; Yang, Xiaoling; Lu, Runhua; Zhang, Sanbing; Gao, Haixiang; Zhou, Wenfeng

2016-02-04

In this work, a novel effervescence-assisted microextraction technique was proposed for the detection of four fungicides. This method combines ionic liquid-based dispersive liquid-liquid microextraction with the magnetic retrieval of the extractant. A magnetic effervescent tablet composed of Fe3O4 magnetic nanoparticles, sodium carbonate, sodium dihydrogen phosphate and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonimide) was used for extractant dispersion and retrieval. The main factors affecting the extraction efficiency were screened by a Plackett-Burman design and optimized by a central composite design. Under the optimum conditions, good linearity was obtained for all analytes in pure water model and real water samples. Just for the pure water, the recoveries were between 84.6% and 112.8%, the limits of detection were between 0.02 and 0.10 μg L(-1) and the intra-day precision and inter-day precision both are lower than 4.9%. This optimized method was successfully applied in the analysis of four fungicides (azoxystrobin, triazolone, cyprodinil, trifloxystrobin) in environmental water samples and the recoveries ranged between 70.7% and 105%. The procedure promising to be a time-saving, environmentally friendly, and efficient field sampling technique. Copyright © 2015 Elsevier B.V. All rights reserved.

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

Rapid determination of alkaloids in Macleaya cordata using ionic liquid extraction followed by multiple reaction monitoring UPLC-MS/MS analysis.

PubMed

Li, Linqiu; Huang, Mingyuan; Shao, Junli; Lin, Bokun; Shen, Qing

2017-02-20

The ultrasonic-assisted extraction (UAE) and ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME) have been successfully applied in extracting of six alkaloids from M. cordata. 1-hexyl-3-methylimidazolium tetrafluoroborate ([C 6 MIM][BF 4 ]) aqueous solution was used as extraction solvent. The target analytes in raw material were deposited into a single drop of 1-hexyl-3-methylimidazolium hexafluorophosphate ([C 6 MIM][PF 6 ]), which was in situ formed by mixing [C 6 MIM][BF 4 ] and potassium hexafluorophosphate ([K][PF 6 ]. Afterwards, the extract was analyzed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) in multiple-reaction monitoring (MRM) mode. The proposed method was fully validated in terms of linearity (0.9983-0.9992), LOD (0.080ngmL -1 ), LOQ (0.25ngmL -1 ), intra-day precision (<5.46%), inter-day precision (<6.36%), and recovery (86.42-112.48%). The results indicate that the approach of combining IL-DLLME with UPLC-MS/MS is powerful and practical for analyzing alkaloids in M. cordata., and it also has great potential for comprehensive quality control of other herbal medicines. Copyright © 2016 Elsevier B.V. All rights reserved.

Hypothesis testing for the validation of the kinetic spectrophotometric methods for the determination of lansoprazole in bulk and drug formulations via Fe(III) and Zn(II) chelates.

PubMed

Rahman, Nafisur; Kashif, Mohammad

2010-03-01

Point and interval hypothesis tests performed to validate two simple and economical, kinetic spectrophotometric methods for the assay of lansoprazole are described. The methods are based on the formation of chelate complex of the drug with Fe(III) and Zn(II). The reaction is followed spectrophotometrically by measuring the rate of change of absorbance of coloured chelates of the drug with Fe(III) and Zn(II) at 445 and 510 nm, respectively. The stoichiometric ratio of lansoprazole to Fe(III) and Zn(II) complexes were found to be 1:1 and 2:1, respectively. The initial-rate and fixed-time methods are adopted for determination of drug concentrations. The calibration graphs are linear in the range 50-200 µg ml⁻¹ (initial-rate method), 20-180 µg ml⁻¹ (fixed-time method) for lansoprazole-Fe(III) complex and 120-300 (initial-rate method), and 90-210 µg ml⁻¹ (fixed-time method) for lansoprazole-Zn(II) complex. The inter-day and intra-day precision data showed good accuracy and precision of the proposed procedure for analysis of lansoprazole. The point and interval hypothesis tests indicate that the proposed procedures are not biased. Copyright © 2010 John Wiley & Sons, Ltd.

An improved analytical strategy combining microextraction by packed sorbent combined with ultra high pressure liquid chromatography for the determination of fluoxetine, clomipramine and their active metabolites in human urine.

PubMed

Alves, Vera; Gonçalves, João; Conceição, Carlota; Teixeira, Helena M; Câmara, José S

2015-08-21

A powerful and sensitive method, by microextraction packed sorbent (MEPS), and ultra-high performance liquid chromatography (UHPLC) with a photodiode array (PDA) detection, is described for the determination of fluoxetine, clomipramine and their active metabolites in human urine samples. The MEPS variables, such as sample volume, pH, number of extraction cycles (draw-eject), and desorption conditions (solvent and solvent volume of elution) were optimized. The analysis were carried out using small sample volumes (500μL) and in a short time period (5min for the entire sample preparation step). Good linearity was obtained for all antidepressants with the correlation coefficients (R(2)) above 0.9965. The limits of detection (LOD) ranged from 0.068 to 0.087μgmL(-1). The recoveries were from 93% to 98%, with relative standard deviations less than 6%. The inter-day precision, expressed as the relative standard deviation, varied between 3.8% and 8.5% while the intra-day precision between 3.0% and 7.1%. In order to evaluate the proposed method for clinical use, the MEPS/UHPLC-PDA method was applied to analysis of urine samples from depressed patients. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of quinolones and fluoroquinolones, tetracyclines and sulfonamides in bovine, swine and poultry liver using LC-MS/MS.

PubMed

Martins, Magda Targa; Barreto, Fabiano; Hoff, Rodrigo Barcelos; Jank, Louise; Arsand, Juliana Bazzan; Feijó, Tiago Correa; Schapoval, Elfrides Eva Scherman

2015-01-01

Antibacterials are widely used in veterinary medicine. Residues of these drugs can remain in food of animal origin, including bovine liver. This paper describes a fast and simple analytical method for the determination of quinolones and fluoroquinolones, tetracyclines and sulfonamides in bovine liver samples. Deuterated enrofloxacin, sulfapyridine and demeclocycline were used as internal standards. The homogenised liver samples were extracted with acidified acetonitrile. Steps of non-solid-phase extraction (SPE) clean-up and concentration were used in the presented method. The final extracts were analysed by sensitive and selective detection of all components in a single run using LC-MS/MS. Acceptable recoveries between 66% and 110% were obtained. Good linearity (r(2)) above 0.96, considering three different days, for all drugs was achieved in concentrations ranging from 0.0 to 2.0 × the maximum residue limit (MRL). Intraday precision with coefficient of variation (CV%) (n = 6) lower than 14.7% and inter-day precision lower than 18.8% in agreement with European Commission Decision 2002/657/EC were obtained in concentrations ranging from 0.5 to 1.5 MRL. Accuracy was between 86% and 110%. Limits of detection and quantitation, as well as decision limit (CCα) and detection capability (CCβ), were also evaluated.

Efficacy of passive sampler collection for atmospheric NO2 isotopes under simulated environmental conditions.

PubMed

Coughlin, Justin G; Yu, Zhongjie; Elliott, Emily M

2017-07-30

Nitrogen oxides or NO x (NO x = NO + NO 2 ) play an important role in air quality, atmospheric chemistry, and climate. The isotopic compositions of anthropogenic and natural NO 2 sources are wide-ranging, and they can be used to constrain sources of ambient NO 2 and associated atmospheric deposition of nitrogen compounds. While passive sample collection of NO 2 isotopes has been used in field studies to determine NO x source influences on atmospheric deposition, this approach has not been evaluated for accuracy or precision under different environmental conditions. The efficacy of NO 2 passive sampler collection for NO 2 isotopes was evaluated under varied temperature and relative humidity (RH) conditions in a dynamic flux chamber. The precision and accuracy of the filter NO 2 collection as nitrite (NO 2 - ) for isotopic analysis were determined using a reference NO 2 gas tank and through inter-calibration with a modified EPA Method 7. The bacterial denitrifer method was used to convert 20 μM of collected NO 2 - or nitrate (NO 3 - ) into N 2 O and was carried out on an Isoprime continuous flow isotope ratio mass spectrometer. δ 15 N-NO 2 values determined from passive NO 2 collection, in conditions of 11-34 °C, 1-78% RH, have an overall accuracy and precision of ±2.1 ‰, and individual run precision of ±0.6 ‰. δ 18 O-NO 2 values obtained from passive NO 2 sampler collection, under the same conditions, have an overall precision of ± 1.3 ‰. Suitable conditions for passive sampler collection of NO 2 isotopes are in environments ranging from 11 to 34 °C and 1 to 78% RH. The passive NO 2 isotope measurement technique provides an accurate method to determine variations in atmospheric δ 15 N-NO 2 values and a precise method for determining atmospheric δ 18 O-NO 2 values. The ability to measure NO 2 isotopes over spatial gradients at the same temporal resolution provides a unique perspective on the extent and seasonality of fluctuations in atmospheric NO 2 isotopic compositions. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Validity of a smartphone protractor to measure sagittal parameters in adult spinal deformity.

PubMed

Kunkle, William Aaron; Madden, Michael; Potts, Shannon; Fogelson, Jeremy; Hershman, Stuart

2017-10-01

Smartphones have become an integral tool in the daily life of health-care professionals (Franko 2011). Their ease of use and wide availability often make smartphones the first tool surgeons use to perform measurements. This technique has been validated for certain orthopedic pathologies (Shaw 2012; Quek 2014; Milanese 2014; Milani 2014), but never to assess sagittal parameters in adult spinal deformity (ASD). This study was designed to assess the validity, reproducibility, precision, and efficiency of using a smartphone protractor application to measure sagittal parameters commonly measured in ASD assessment and surgical planning. This study aimed to (1) determine the validity of smartphone protractor applications, (2) determine the intra- and interobserver reliability of smartphone protractor applications when used to measure sagittal parameters in ASD, (3) determine the efficiency of using a smartphone protractor application to measure sagittal parameters, and (4) elucidate whether a physician's level of experience impacts the reliability or validity of using a smartphone protractor application to measure sagittal parameters in ASD. An experimental validation study was carried out. Thirty standard 36″ standing lateral radiographs were examined. Three separate measurements were performed using a marker and protractor; then at a separate time point, three separate measurements were performed using a smartphone protractor application for all 30 radiographs. The first 10 radiographs were then re-measured two more times, for a total of three measurements from both the smartphone protractor and marker and protractor. The parameters included lumbar lordosis, pelvic incidence, and pelvic tilt. Three raters performed all measurements-a junior level orthopedic resident, a senior level orthopedic resident, and a fellowship-trained spinal deformity surgeon. All data, including the time to perform the measurements, were recorded, and statistical analysis was performed to determine intra- and interobserver reliability, as well as accuracy, efficiency, and precision. Statistical analysis using the intra- and interclass correlation coefficient was calculated using R (version 3.3.2, 2016) to determine the degree of intra- and interobserver reliability. High rates of intra- and interobserver reliability were observed between the junior resident, senior resident, and attending surgeon when using the smartphone protractor application as demonstrated by high inter- and intra-class correlation coefficients greater than 0.909 and 0.874 respectively. High rates of inter- and intraobserver reliability were also seen between the junior resident, senior resident, and attending surgeon when a marker and protractor were used as demonstrated by high inter- and intra-class correlation coefficients greater than 0.909 and 0.807 respectively. The lumbar lordosis, pelvic incidence, and pelvic tilt values were accurately measured by all three raters, with excellent inter- and intra-class correlation coefficient values. When the first 10 radiographs were re-measured at different time points, a high degree of precision was noted. Measurements performed using the smartphone application were consistently faster than using a marker and protractor-this difference reached statistical significance of p<.05. Adult spinal deformity radiographic parameters can be measured accurately, precisely, reliably, and more efficiently using a smartphone protractor application than with a standard protractor and wax pencil. A high degree of intra- and interobserver reliability was seen between the residents and attending surgeon, indicating measurements made with a smartphone protractor are unaffected by an observer's level of experience. As a result, smartphone protractors may be used when planning ASD surgery. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Inter- and intra-individual variation in urinary biomarker concentrations over a 6-day sampling period. Part 1: metals.

PubMed

Smolders, Roel; Koch, Holger M; Moos, Rebecca K; Cocker, John; Jones, Kate; Warren, Nick; Levy, Len; Bevan, Ruth; Hays, Sean M; Aylward, Lesa L

2014-12-01

The aim of the current HBM-study is to further the understanding of the impact of inter- and intra-individual variability in HBM surveys as it may have implications for the design and interpretation of the study outcomes. As spot samples only provide a snapshot in time of the concentrations of chemicals in an individual, it remains unclear to what extent intra-individual variability plays a role in the overall variability of population-wide HBM surveys. The current paper describes the results of an intensive biomonitoring study, in which all individual urine samples of 8 individuals were collected over a 6-day sampling period (a total of 352 unique samples). By analyzing different metals (As, Cd, Mn, Ni) in each individual sample, inter- and intra-individual variability for these four metals could be determined, and the relationships between exposure, internal dose, and sampling protocol assessed. Although the range of biomarker values for different metals was well within the normal range reported in large-scale population surveys, large intra-individual differences over a 6-day period could also be observed. Typically, measured biomarker values span at least an order of magnitude within an individual, and more if specific exposure episodes could be identified. Fish consumption for example caused a twenty- to thirty-fold increase in urinary As-levels over a period of 2-6h. Intra-class correlation coefficients (ICC) were typically low for uncorrected biomarker values (between 0.104 and 0.460 for the 4 metals), but improved when corrected for creatinine or specific gravity (SG). The results show that even though urine is a preferred matrix for HBM studies, there are certain methodological issues that need to be taken into account in the interpretation of urinary biomarker data, related to the intrinsic variability of the urination process itself, the relationship between exposure events and biomarker quantification, and the timing of sampling. When setting up HBM-projects, this expected relationship between individual exposure episode and urinary biomarker concentration needs to be taken into account. Copyright © 2014. Published by Elsevier Ireland Ltd.

Assessment of different methods to estimate bovine colostrum quality on farm.

PubMed

Bartens, M-C; Drillich, M; Rychli, K; Iwersen, M; Arnholdt, T; Meyer, L; Klein-Jöbstl, D

2016-09-01

To evaluate two different hydrometers and an optical and a digital Brix refractometer for the assessment of bovine colostrum quality, in terms of accuracy and precision compared with the measurement of IgG concentrations using radial immunodiffusion (RID), and to evaluate the reliability and repeatability of the Brix refractometers. To determine reliability and repeatability, 145 colostrum samples were tested by two independent observers twice, using the optical and digital Brix refractometers. A further 193 colostrum samples from Holstein cows were collected on one commercial dairy farm at first milking and tested with two hydrometers and an optical and digital Brix refractometer. An aliquot of each sample was frozen for RID measurement of IgG concentrations and samples were classified as poor (≤50 g IgG/L) or good (>50 g IgG/L) quality colostrum. Intraclass correlation coefficients (ICC) were used to determine inter- and intra-observer reliability and repeatability. Optimised cut-off values for the four devices were determined using receiver operating characteristics (ROC) analysis with the RID results as the reference. Using these cut-offs, sensitivities and specificities for determining good quality colostrum were calculated. The ICC for inter-observer reliability was 0.98 for the optical Brix refractometer, and for intra-observer repeatability was 0.97 and 0.98 for the optical and the digital Brix refractometers, respectively. For the 193 colostrum samples, 67 (34.7%) had concentrations of IgG ≤50 g/L determined by RID. Optimised cut-off values evaluated by ROC analysis were higher for all devices compared with manufacturer reference or previously published values. Using these values, the sensitivities for the two hydrometers, and the optical and the digital Brix refractometers were 0.73, 0.71, 0.56 and 0.79, respectively; specificities were 0.72, 0.61, 0.90 and 0.69, respectively. The Brix refractometers provided the most accurate assessment of colostrum quality of the devices evaluated, and demonstrated excellent precision in terms of repeatability. To provide optimal health for newborn calves, a sufficient intake of good quality colostrum is essential. The Brix refractometers provide rapid, convenient tools for classification of colostrum quality.

The Influence of Daily Stress on Sedentary Behavior: Group and Person (N of 1) Level Results of a 1-Year Observational Study.

PubMed

Diaz, Keith M; Thanataveerat, Anusorn; Parsons, Faith E; Yoon, Sunmoo; Cheung, Ying Kuen; Alcantara, Carmela; Duran, Andrea T; Ensari, Ipek; Krupka, David J; Schwartz, Joseph E; Burg, Matthew M; Davidson, Karina W

2018-05-24

The purpose of this study, which used mobile technologies to continuously collect data over 1 year, was to examine the association of psychological stress with objectively measured sedentary behavior in adults at both the group (e.g. nomothetic approach) and individual (e.g. idiographic approach) level. Data were collected in an observational study of healthy adults (n=79) residing in the New York City metro area who were studied for 365 days from 2014-2015. Sedentary behavior was objectively measured via accelerometry. A smartphone-based electronic diary was used to assess level of stress ("Overall, how stressful was your day?"; 0-10 scale) and sources of stress. The end-of-day stress rating was not associated with total sedentary time (B= -1.34, p=0.767) at the group-level. When specific sources of stress were evaluated at the group-level, argument-related stress was associated with increased sedentariness; while running late- and work-related stress were associated with decreased sedentariness. There was a substantial degree of inter-individual variability in the relationship of stress with sedentary behavior. Both the level and sources of stress were associated with increased sedentariness for some, decreased sedentariness for others, and had no effect for many (within-person variance p-value <0.001). These findings suggest that the influence of stress on sedentary behavior varies by source of stress and from person-to-person. A precision medicine approach may be warranted to target reductions in sedentary time; although further studies are needed to confirm the observed findings in light of study limitations including a small sample size and enrollment of participants from a single, urban metropolitan area.

Analytical studies on the charge transfer complexes of loperamide hydrochloride and trimebutine drugs. Spectroscopic and thermal characterization of CT complexes.

PubMed

Elqudaby, Hoda M; Mohamed, Gehad G; El-Din, Ghada M G

2014-08-14

Charge transfer complexes of loperamide hydrochloride (LOP.HCl) and trimebutine (TB) drugs as electron donor with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π-acceptors in acetonitrile were investigated spectrophotometrically to determine the cited drugs in pure and dosage forms. The reaction gives highly coloured complex species which are measured spectrophotometrically at 460, 415 and 842nm in case of LOP.HCl and at 455, 414 and 842nm in case of TB using DDQ, TCNE and TCNQ reagents, respectively. The optimum experimental conditions have been studied carefully and optimized. Beer's law was obeyed over the concentration ranges of 47.70-381.6, 21.50-150.5 and 10.00-100.0μgmL(-1) for LOP.HCl and 37.85-264.9, 38.75-310.0 and 7.75-155.0μgmL(-1) for TB using DDQ, TCNE and TCNQ reagents, respectively. Sandell sensitivity, standard deviation, relative standard deviation, limit of detection and quantification were calculated. The obtained data refer to high accuracy and precision of the proposed method. These results are also confirmed by inter and intra-day precision with percent recovery of 99.18-101.1% and 99.32-101.4% in case of LOP.HCl and 98.00-102.0% and 97.50-101.4% in case of TB using DDQ, TCNE and TCNQ reagents for intra- and inter-day, respectively. These data were compared with those obtained using official methods for the determination of the cited drugs. The stability constants of the CT complexes were determined. The final products of the reaction were isolated and characterized using FT-IR, (1)H NMR, elemental analysis and thermogravimetric analysis (TG). The stoichiometry and apparent formation constant of the complexes formed were determined by applying the conventional spectrophotometric molar ratio method. Copyright © 2014 Elsevier B.V. All rights reserved.

Liquid chromatography-mass spectrometry method for the quantification of tamoxifen and its metabolite 4-hydroxytamoxifen in rat plasma: application to interaction study with biochanin A (an isoflavone).

PubMed

Singh, Sheelendra Pratap; Wahajuddin; Ali, Mushir M; Kohli, Kanchan; Jain, Girish Kumar

2011-10-01

Tamoxifen is the agent of choice for the treatment of estrogen receptor-positive breast cancer. Tamoxifen is a substrate of P-glycoprotein (P-gp) and microsomal cytochrome P450 (CYP) 3A, and biochanin A (BCA) is an inhibitor of P-gp and CYP3A. Hence, it could be expected that BCA would affect the pharmacokinetics of tamoxifen. In the present study we have developed and validated a simple, sensitive and specific LC-ESI-MS/MS method for the simultaneous quantification of tamoxifen and its metabolite 4-hydroxytamoxifen with 100 μL rat plasma using centchroman as an internal standard (IS). Tamoxifen, 4-hydroxytamoxifen and IS were separated on a Supelco Discovery C18 (4.6 mm × 50 mm, 5.0 μm) column under isocratic condition using 0.0 1M ammonium acetate (pH 4.5):acetonitrile (10:90, v/v) as a mobile phase. The mobile phase was delivered at a flow rate of 0.8 mL/min. The method was proved to be accurate and precise at linearity range of 0.78-200 ng/mL with a correlation coefficient (r) of ≥ 0.996. The intra- and inter-day assay precision ranged from 1.89 to 8.54% and 3.97 to 10.26%, respectively; and intra- and inter-day assay accuracy was between 87.63 and 109.06% and 96 and 103.89%, respectively for both the analytes. The method was successfully applied to study the effect of oral co-administration of BCA (an isoflavone) on the pharmacokinetics of tamoxifen and 4-hydroxytamoxifen in female rats. The coadministration of BCA caused no significant changes in the pharmacokinetics of tamoxifen and 4-hydroxytamoxifen. However, the peak plasma concentration (C(max)) of 4-hydroxytamoxifen in BCA pretreated rats was significantly (P<0.05) lower than those from control group. Copyright © 2011 Elsevier B.V. All rights reserved.

LC-MS/MS method for the simultaneous quantification of luteolin, wedelolactone and apigenin in mice plasma using hansen solubility parameters for liquid-liquid extraction: Application to pharmacokinetics of Eclipta alba chloroform fraction.

PubMed

Cheruvu, Hanumanth Srikanth; Yadav, Navneet K; Valicherla, Guru R; Arya, Rakesh K; Hussain, Zakir; Sharma, Chetan; Arya, Kamal R; Singh, Rama K; Datta, Dipak; Gayen, Jiaur R

2018-04-01

Eclipta alba (Bhringraj) in ayurveda has been widely used as a traditional medicine for its multi-therapeutic properties for ages. Luteolin (LTL), wedelolactone (WDL) and apigenin (APG) are the three main bioactive phytochemicals present in Eclipta alba extract. However there was a lack of sensitive bioanalytical method for the pharmacokinetics of these free compounds in plasma which majorly contributes for their activities after oral administration of Eclipta alba. The present study aims to develop a sensitive, rapid and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous estimation of mice plasma concentrations of LTL, WDL and APG using quercetin as an internal standard for the pharmacokinetic analysis. Analytes were separated on Phenomenex Luna C18 (150 × 4.6 mm, 3.0 μm) column with mobile phase containing methanol: acetonitrile (90: 10, v/v) and 0.1% formic acid in 10 mM ammonium formate buffer in the ratio of 70: 30 (v/v) in isocratic mode. Liquid-liquid extraction was optimized using Hansen solubility parameters and diethyl ether finalized as an extraction solvent for the recovery ranging from 61 to 76% for all analytes in mice plasma. The validated method has an accuracy and precision over the linearity range of 0.1-200 ng/mL with a correlation coefficient (r 2 ) of ≥0.997. The intra and inter-day assay accuracy was between 98.17 and 107% and 95.83-107.89% respectively and the intra and inter day assay precision ranged from 0.37-6.05% and 1.85-10.76%, respectively for all the analytes. This validated method can be used for future clinical investigation studies of Eclipta alba extracts. Copyright © 2018 Elsevier B.V. All rights reserved.

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

PubMed

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

2017-11-01

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

Simultaneous determination of the novel tyrosine kinase inhibitor meditinib and its active metabolite demethylation meditinib in monkey plasma by liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic studies.

PubMed

Liang, Feng; Kong, Qi; Guo, Yongqi; Wang, Yu; Sun, Dejie; Liu, Shi; Cai, Jinling; Guan, Yongbiao; Ding, Rigao

2015-08-01

Meditinib (ME) is a novel tyrosine kinase inhibitor used as an antichronic myeloid leukemia drug. A simple, sensitive and specific LC/MS/MS method was developed and validated for the analysis of ME and its metabolite demethylation meditinib (PI) in monkey plasma using naltrexone as the internal standard. Sample preparation involved protein precipitation with methanol. The analysis was carried out on an Agilent C8 column (3.5 µm, 2.1 × 50 mm). Elution was achieved with a mobile phase gradient varying the proportion of a water solution containing 0.1% formic acid (solvent A) and a 0.1% formic acid in methanol solution (solvent B) at a flow rate of 300 μL/min. The method had a linear calibration curve over the concentration range of 2-1000 ng/mL for ME and 2-1000 ng/mL for PI. The lower limits of quantification of ME and PI were 2 and 2 ng/mL, respectively. The intra- and inter-day precision values were <15% and accuracy values were within ±10.0%. The mean recoveries of ME and PI from plasma were >85%. The assay has been successfully used for pharmacokinetic evaluation of ME and PI using the monkey as an animal model, and those data are reported for the first time. Copyright © 2015 John Wiley & Sons, Ltd.

Highly Sensitive and Validated Spectrophotometric Technique for the Assay of Some Antidepressant Drugs

NASA Astrophysics Data System (ADS)

Deepakumari, H. N.; Prashanth, M. K.; Kumar, B. C. Vasantha; Revanasiddappa, H. D.

2015-01-01

The present paper describes a simple, rapid, reproducible, and highly sensitive spectrophotometric method for the determination of the tricyclic antidepressant drugs: amitriptyline hydrochloride (AMT), imipramine hydrochloride (IMH), clomipramine hydrochloride (CPH) and desipramine hydrochloride (DPH) in pure and in pharmaceutical preparations. The method is based on the bromination of the above drugs with known excess of bromine. The unreacted bromine is determined based on its ability to bleach the dye methyl red quantitatively at 520 nm. Regression analysis of Beer-Lambert plots showed a good correlation in the concentration range 0.0-2.5, 0-1.4, 0-1.4, and 0-1.0 μg/ml for AMT, IMH, CPH, and DPH, respectively. The molar absorptivity values were found to be 0.65 × 105, 1.41 × 105, 1.93 × 105, and 2.96 × 105l/mol/cm, with the corresponding Sandell's sensitivity values were 0.0048, 0.0022, 0.0018, and 0.0010 μg/cm2 for AMT, IMH, CPH, and DPH, respectively. The limits of detection (LOD) and quantification (LOQ) are also reported for the developed method. Intra- and inter-day accuracy and precision was established according to the current ICH guidelines. Application of the procedure to the analysis of various pharmaceutical preparations gave reproducible and accurate results. Further, the validity of the proposed method was confirmed by applying the standard addition technique, and the results obtained are in good agreement with those obtained by the official method.

A demonstration of high precision GPS orbit determination for geodetic applications

NASA Technical Reports Server (NTRS)

Lichten, S. M.; Border, J. S.

1987-01-01

High precision orbit determination of Global Positioning System (GPS) satellites is a key requirement for GPS-based precise geodetic measurements and precise low-earth orbiter tracking, currently under study at JPL. Different strategies for orbit determination have been explored at JPL with data from a 1985 GPS field experiment. The most successful strategy uses multi-day arcs for orbit determination and includes fine tuning of spacecraft solar pressure coefficients and station zenith tropospheric delays using the GPS data. Average rms orbit repeatability values for 5 of the GPS satellites are 1.0, 1.2, and 1.7 m in altitude, cross-track, and down-track componenets when two independent 5-day fits are compared. Orbit predictions up to 24 hours outside the multi-day arcs agree within 4 m of independent solutions obtained with well tracked satellites in the prediction interval. Baseline repeatability improves with multi-day as compared to single-day arc orbit solutions. When tropospheric delay fluctuations are modeled with process noise, significant additional improvement in baseline repeatability is achieved. For a 246-km baseline, with 6-day arc solutions for GPS orbits, baseline repeatability is 2 parts in 100 million (0.4-0.6 cm) for east, north, and length components and 8 parts in 100 million for the vertical component. For 1314 and 1509 km baselines with the same orbits, baseline repeatability is 2 parts in 100 million for the north components (2-3 cm) and 4 parts in 100 million or better for east, length, and vertical components.

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

PubMed

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

2015-05-15

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

Inter- and intra-operator reliability and repeatability of shear wave elastography in the liver: a study in healthy volunteers.

PubMed

Hudson, John M; Milot, Laurent; Parry, Craig; Williams, Ross; Burns, Peter N

2013-06-01

This study assessed the reproducibility of shear wave elastography (SWE) in the liver of healthy volunteers. Intra- and inter-operator reliability and repeatability were quantified in three different liver segments in a sample of 15 subjects, scanned during four independent sessions (two scans on day 1, two scans 1 wk later) by two operators. A total of 1440 measurements were made. Reproducibility was assessed using the intra-class correlation coefficient (ICC) and a repeated measures analysis of variance. The shear wave speed was measured and used to estimate Young's modulus using the Supersonics Imagine Aixplorer. The median Young's modulus measured through the inter-costal space was 5.55 ± 0.74 kPa. The intra-operator reliability was better for same-day evaluations (ICC = 0.91) than the inter-operator reliability (ICC = 0.78). Intra-observer agreement decreased when scans were repeated on a different day. Inter-session repeatability was between 3.3% and 9.9% for intra-day repeated scans, compared with to 6.5%-12% for inter-day repeated scans. No significant difference was observed in subjects with a body mass index greater or less than 25 kg/m(2). Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Multiple-Baseline Detection of a Geostationary Satellite with the Navy Precision Optical Interferometer

DTIC Science & Technology

2015-01-01

Multiple-baseline detection of a geostationary satellite with the Navy Precision Optical Interferometer J. Thomas Armstronga, Ellyn K. Bainesa...observations of a geostationary satellite using the Navy Precision Optical Inter- ferometer (NPOI) during the glint season of March 2015. We succeeded in...the second night. These baseline lengths correspond to a resolution of ∼4 m at geostationary altitude. This is the first multiple-baseline

Rainfall extremes from TRMM data and the Metastatistical Extreme Value Distribution

NASA Astrophysics Data System (ADS)

Zorzetto, Enrico; Marani, Marco

2017-04-01

A reliable quantification of the probability of weather extremes occurrence is essential for designing resilient water infrastructures and hazard mitigation measures. However, it is increasingly clear that the presence of inter-annual climatic fluctuations determines a substantial long-term variability in the frequency of occurrence of extreme events. This circumstance questions the foundation of the traditional extreme value theory, hinged on stationary Poisson processes or on asymptotic assumptions to derive the Generalized Extreme Value (GEV) distribution. We illustrate here, with application to daily rainfall, a new approach to extreme value analysis, the Metastatistical Extreme Value Distribution (MEVD). The MEVD relaxes the above assumptions and is based on the whole distribution of daily rainfall events, thus allowing optimal use of all available observations. Using a global dataset of rain gauge observations, we show that the MEVD significantly outperforms the Generalized Extreme Value distribution, particularly for long average recurrence intervals and when small samples are available. The latter property suggests MEVD to be particularly suited for applications to satellite rainfall estimates, which only cover two decades, thus making extreme value estimation extremely challenging. Here we apply MEVD to the TRMM TMPA 3B42 product, an 18-year dataset of remotely-sensed daily rainfall providing a quasi-global coverage. Our analyses yield a global scale mapping of daily rainfall extremes and of their distributional tail properties, bridging the existing large gaps in ground-based networks. Finally, we illustrate how our global-scale analysis can provide insight into how properties of local rainfall regimes affect tail estimation uncertainty when using the GEV or MEVD approach. We find a dependence of the estimation uncertainty, for both the GEV- and MEV-based approaches, on the average annual number and on the inter-annual variability of rainy days. In particular, estimation uncertainty decreases 1) as the mean annual number of wet days increases, and 2) as the variability in the number of rainy days, expressed by its coefficient of variation, decreases. We tentatively explain this behavior in terms of the assumptions underlying the two approaches.

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.

Micro-scale method for liquid-chromatographic determination of chloramphenicol in serum.

PubMed

Petersdorf, S H; Raisys, V A; Opheim, K E

1979-07-01

We describe the use of "high-performance" liquid chromatography to measure chloramphenicol in as little as 25 microL of serum. Serum is treated to precipitate proteins with acetonitrile containing p-nitroacetanilide as an internal standard. Chloramphenicol is eluted with a mobile phase of methanol in pH 7.0 phosphate buffer (35/65 by vol). The drug is measured at 278 nm and simultaneously monitored at 254 nm; interfering substances are detected by examining the 278 nm/254 absorbance ratios. This method is sensitive to less than 0.5 mg/L and the standard curve is linear to at least 50 mg/L. Inter-day precision ranged between 3--6%. We encountered no interference from endogenous compounds or from other drugs we tested.

Quantitative analysis of the eight major compounds in the Samsoeum using a high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometer

PubMed Central

Weon, Jin Bae; Yang, Hye Jin; Lee, Bohyoung; Ma, Jin Yeul; Ma, Choong Je

2015-01-01

Background: Samsoeum was traditionally used for treatment of a respiratory disease. Objective: The simultaneous determination of eight major compounds, ginsenoside Rg3, caffeic acid, puerarin, costunolide, hesperidin, naringin, glycyrrhizin, and 6-gingerol in the Samsoeum using a high-performance liquid chromatography (HPLC) coupled with diode array detection (DAD) and an electrospray ionization mass spectrometer was developed for an accurate and reliable quality assessment. Materials and Methods: Eight compounds were qualitative identified based on their mass spectra and by comparing with standard compounds and quantitative analyzed by HPLC-DAD. Separation of eight compounds was carried out on a LUNA C18 column (S-5 μm, 4.6 mm i.d. ×250 mm) with gradient elution composed of acetonitrile and 0.1% trifluoroacetic acid. Results: The data showed good linearity (R2 > 0.9996). The limits of detection and the limits of quantification were <0.53 μg and 1.62 μg, respectively. Inter- and Intra-day precisions (expressed as relative standard deviation values) were within 1.94% and 1.91%, respectively. The recovery of the method was in the range of 94.24–107.90%. Conclusion: The established method is effective and could be applied to quality control of Samsoeum. PMID:25829771

Application of High-Performance Liquid Chromatography Coupled with Linear Ion Trap Quadrupole Orbitrap Mass Spectrometry for Qualitative and Quantitative Assessment of Shejin-Liyan Granule Supplements.

PubMed

Gu, Jifeng; Wu, Weijun; Huang, Mengwei; Long, Fen; Liu, Xinhua; Zhu, Yizhun

2018-04-11

A method for high-performance liquid chromatography coupled with linear ion trap quadrupole Orbitrap high-resolution mass spectrometry (HPLC-LTQ-Orbitrap MS) was developed and validated for the qualitative and quantitative assessment of Shejin-liyan Granule. According to the fragmentation mechanism and high-resolution MS data, 54 compounds, including fourteen isoflavones, eleven ligands, eight flavonoids, six physalins, six organic acids, four triterpenoid saponins, two xanthones, two alkaloids, and one licorice coumarin, were identified or tentatively characterized. In addition, ten of the representative compounds (matrine, galuteolin, tectoridin, iridin, arctiin, tectorigenin, glycyrrhizic acid, irigenin, arctigenin, and irisflorentin) were quantified using the validated HPLC-LTQ-Orbitrap MS method. The method validation showed a good linearity with coefficients of determination (r²) above 0.9914 for all analytes. The accuracy of the intra- and inter-day variation of the investigated compounds was 95.0-105.0%, and the precision values were less than 4.89%. The mean recoveries and reproducibilities of each analyte were 95.1-104.8%, with relative standard deviations below 4.91%. The method successfully quantified the ten compounds in Shejin-liyan Granule, and the results show that the method is accurate, sensitive, and reliable.

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

PubMed

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

2013-03-01

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

Determination of aminopolycarboxylic acids in river water by solid-phase extraction on activated charcoal cartridges and gas chromatography with mass spectrometric detection. Method performance characteristics and estimation of the uncertainty.

PubMed

Jiménez, Juan J

2013-04-03

A new sample preparation procedure to determine aminopolycarboxylic acids (ethylenediaminetetraacetic acid, EDTA, nitrilotriacetic acid, NTA, diethylenetriaminepentaacetic acid, DTPA, and cyclohexanediaminetetraacetic acid, CDTA) in river water is described. The procedure consists of the solid-phase extraction of the aminopolycaroxyllic acids on activated charcoal cartridges after increasing the ionic strength and acidifying the sample. The extract was eluted with methanol and the analytes were methylated in presence of BF3/methanol to determine them by GC with mass spectrometric detection. Recoveries were higher than 90% with good repeatabilities and inter-day precision for concentrations close to quantification limits (about 10 μg L(-1)) and higher. It has been verified that the proposed method is robust according to the Youden and Steiner test and free of matrix effects arisen from the presence of organic matter and iron(III) as deduced from statistical tests. A bottom-up approach was followed to estimate the uncertainty of the measured concentration. At concentrations close to 10 μg L(-1) the most relevant step of the method is the calculus of the interpolated concentration which has a high value of relative standard uncertainty. Copyright © 2013 Elsevier B.V. All rights reserved.

Monolithic Solid Based on Single-Walled Carbon Nanohorns: Preparation, Characterization, and Practical Evaluation as a Sorbent.

PubMed

Fresco-Cala, Beatriz; López-Lorente, Ángela I; Cárdenas, Soledad

2018-05-25

A monolithic solid based solely on single walled carbon nanohorns (SWNHs) was prepared without the need of radical initiators or gelators. The procedure involves the preparation of a wet jelly-like system of pristine SWNHs followed by slow drying (48 h) at 25 °C. As a result, a robust and stable porous network was formed due to the interaction between SWNHs not only via π-π and van der Waals interactions, but also via the formation of carbon bonds similar to those observed within dahlia aggregates. Pristine SWNHs and the SWNH monolith were characterized by several techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), confocal laser scanning microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and nitrogen intrusion porosimetry. Taking into account the efficiency of carbon nanoparticles in sorption processes, the potential applicability of the SWNH-monolith in this research field was explored using toluene; m-, p-, and o-xylene; ethylbenzene; and styrene, as target analytes. Detection limits were 0.01 µg·L -1 in all cases and the inter-day precision was in the interval 7.4⁻15.7%. The sorbent performance of the nanostructured monolithic solid was evaluated by extracting the selected compounds from different water samples with recovery values between 81.5% and 116.4%.

A Conceptual Framework for Tactical Private Satellite Networks

DTIC Science & Technology

2008-09-01

will be deployed on a controlled basis so as not to consume valuable bandwidth during critical time windows. Faults inside the network can be tracked ... attitude control , timing, and navigation - More precise station keeping - Optical LANs and inter-satellite links - Inter satellite links - New...Cluster operations, such as electromagnetic formation flying systems and remote attitude determination systems. • Distributed spacecraft computing

Studies on the Effects of Certain Soil Properties on the Biodegradation of Oils Determined by the Manometric Respirometric Method

PubMed Central

Kaakinen, Juhani; Vähäoja, Pekka; Kuokkanen, Toivo; Roppola, Katri

2007-01-01

The biodegradability of certain biofuels was studied in the case of forest soils using the manometric respirometric technique, which was proved to be very suitable for untreated, fertilized as well as pH adjusted soils. Experiments carried out in infertile sandy forest soil gave a BOD/ThOD value of 45.1% for a typical model substance, that is, sodium benzoate after a period of 30 days and mineral addition improved the BOD/ThOD value to a value of 76.2%. Rapeseed oil-based chain oil almost did not biodegrade at all in 30 days in nonprocessed soil, and when pH was adjusted to 8.0, the BOD/ThOD value increased slightly to a value of 7.4%. Mineral addition improved the BOD/ThOD value on average to 43.2% after 30 days. The combined mineral addition and pH adjustment together increased the BOD/ThOD value to 75.8% in 30 days. The observations were similar with a rapeseed oil-based lubricating oil: after 30 days, the BOD/ThOD value increased from 5.9% to an average value of 51.9%, when the pH and mineral concentrations of the soil were optimized. The mineral addition and pH adjustment also improved the precision of the measurements significantly. PMID:18273392

Superparamagnetic graphene oxide-based dispersive-solid phase extraction for preconcentration and determination of tamsulosin hydrochloride in human plasma by high performance liquid chromatography-ultraviolet detection.

PubMed

Pashaei, Yaser; Ghorbani-Bidkorbeh, Fatemeh; Shekarchi, Maryam

2017-05-26

In the present study, superparamagnetic graphene oxide-Fe 3 O 4 nanocomposites were successfully prepared by a modified impregnation method (MGO mi ) and their application as a sorbent in the magnetic-dispersive solid phase extraction (M-dSPE) mode to the preconcentration and determination of tamsulosin hydrochloride (TMS) in human plasma was investigated by coupling with high performance liquid chromatography-ultraviolet detection (HPLC-UV). The structure, morphology and magnetic properties of the prepared nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). Some factors affecting the extraction efficiency, including the pH value, amount of sorbent, extraction time, elution solvent and its volume, and desorption time were studied and optimized. Magnetic nanocomposites plasma extraction of TMS following HPLC analyses showed a linear calibration curve in the range of 0.5-50.0ngmL -1 with an acceptable correlation coefficient (R 2 =0.9988). The method was sensitive, with a low limit of detection (0.17ngmL -1 ) and quantification (0.48ngmL -1 ). Inter- and intra-day precision expressed as relative standard deviation (n=3) and the preconcentration factor, were found to be 5.6-7.2%, 2.9-4.2% and 10, respectively. Good recoveries (98.1-101.4%) with low relative standard deviations (4.2-5.0%) indicated that the matrices under consideration do not significantly affect the extraction process. Due to its high precision and accuracy, the developed method may be a HPLC-UV alternative with M-dSPE for bioequivalence analysis of TMS in human plasma. Copyright © 2017 Elsevier B.V. All rights reserved.

Dried blood spot testing for seven steroids using liquid chromatography-tandem mass spectrometry with reference interval determination in the Korean population.

PubMed

Kim, Borahm; Lee, Mi Na; Park, Hyung Doo; Kim, Jong Won; Chang, Yun Sil; Park, Won Soon; Lee, Soo Youn

2015-11-01

Conventional screening for congenital adrenal hyperplasia (CAH) using immunoassays generates a large number of false-positive results. A more specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been introduced to minimize unnecessary follow-ups. However, because of limited data on its use in the Korean population, LC-MS/MS has not yet been incorporated into newborn screening programs in this region. The present study aims to develop and validate an LC-MS/MS method for the simultaneous determination of seven steroids in dried blood spots (DBS) for CAH screening, and to define age-specific reference intervals in the Korean population. We developed and validated an LC-MS/MS method to determine the reference intervals of cortisol, 17-hydroxyprogesterone, 11-deoxycortisol, 21-deoxycortisol, androstenedione, corticosterone, and 11-deoxycorticosterone simultaneously in 453 DBS samples. The samples were from Korean subjects stratified by age group (78 full-term neonates, 76 premature neonates, 89 children, and 100 adults). The accuracy, precision, matrix effects, and extraction recovery were satisfactory for all the steroids at three concentrations; values of intra- and inter-day precision coefficients of variance, bias, and recovery were 0.7-7.7%, -1.5-9.8%, and 49.3-97.5%, respectively. The linearity range was 1-100 ng/mL for cortisol and 0.5-50 ng/mL for other steroids (R²>0.99). The reference intervals were in agreement with the previous reports. This LC-MS/MS method and the reference intervals validated in the Korean population can be successfully applied to analyze seven steroids in DBS for the diagnosis of CAH.

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

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 .

Mutual information-based feature selection for radiomics

NASA Astrophysics Data System (ADS)

Oubel, Estanislao; Beaumont, Hubert; Iannessi, Antoine

2016-03-01

Background The extraction and analysis of image features (radiomics) is a promising field in the precision medicine era, with applications to prognosis, prediction, and response to treatment quantification. In this work, we present a mutual information - based method for quantifying reproducibility of features, a necessary step for qualification before their inclusion in big data systems. Materials and Methods Ten patients with Non-Small Cell Lung Cancer (NSCLC) lesions were followed over time (7 time points in average) with Computed Tomography (CT). Five observers segmented lesions by using a semi-automatic method and 27 features describing shape and intensity distribution were extracted. Inter-observer reproducibility was assessed by computing the multi-information (MI) of feature changes over time, and the variability of global extrema. Results The highest MI values were obtained for volume-based features (VBF). The lesion mass (M), surface to volume ratio (SVR) and volume (V) presented statistically significant higher values of MI than the rest of features. Within the same VBF group, SVR showed also the lowest variability of extrema. The correlation coefficient (CC) of feature values was unable to make a difference between features. Conclusions MI allowed to discriminate three features (M, SVR, and V) from the rest in a statistically significant manner. This result is consistent with the order obtained when sorting features by increasing values of extrema variability. MI is a promising alternative for selecting features to be considered as surrogate biomarkers in a precision medicine context.

Poster - 53: Improving inter-linac DMLC IMRT dose precision by fine tuning of MLC leaf calibration

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

Nakonechny, Keith; Tran, Muoi; Sasaki, David

Purpose: To develop a method to improve the inter-linac precision of DMLC IMRT dosimetry. Methods: The distance between opposing MLC leaf banks (“gap size”) can be finely tuned on Varian linacs. The dosimetric effect due to small deviations from the nominal gap size (“gap error”) was studied by introducing known errors for several DMLC sliding gap sizes, and for clinical plans based on the TG119 test cases. The plans were delivered on a single Varian linac and the relationship between gap error and the corresponding change in dose was measured. The plans were also delivered on eight Varian 2100 seriesmore » linacs (at two institutions) in order to quantify the inter-linac variation in dose before and after fine tuning the MLC calibration. Results: The measured dose differences for each field agreed well with the predictions of LoSasso et al. Using the default MLC calibration, the variation in the physical MLC gap size was determined to be less than 0.4 mm between all linacs studied. The dose difference between the linacs with the largest and smallest physical gap was up to 5.4% (spinal cord region of the head and neck TG119 test case). This difference was reduced to 2.5% after fine tuning the MLC gap calibration. Conclusions: The inter-linac dose precision for DMLC IMRT on Varian linacs can be improved using a simple modification of the MLC calibration procedure that involves fine adjustment of the nominal gap size.« less

Short-term absence from industry: II Temporal variation and inter-association with other recorded factors

PubMed Central

Froggatt, P.

1970-01-01

Froggatt, P. (1970).Brit. J. industr. Med.,27, 211-224. Short-term absence from industry. II. Temporal variation and inter-association with other recorded factors. This paper (a) extends the previous analysis (Froggatt, 1970b) of short-term absence from work among groups of male and female industrial personnel and clerks in government service, and (b) studies other recorded variables, particularly lateness, long-term sickness absence, and passes from work both `medical' and `works'. Multiple regression shows one-day absences to be generally associated with two-day absences, lateness, and medical passes but independent of works passes and long-term sickness absence; and two-day absences to be generally associated with one-day absences and long-term sickness absence but not with lateness or passes from work. Higher order correlations show lateness and works passes, medical passes and works passes, and lateness and age to be (weakly) associated, the last negatively. Irrespective of season, one-day absences were consistently most prevalent on Monday and least so on Friday, with a subsidiary peak for the male groups on Wednesday; two-day absences - as measured by the day each absence starts - were consistently most prevalent on Monday and least so on Thursday (Friday was omitted) and during the summer months. Medical passes were generally independent of the day of the week and the period of the year; lateness was greatest on Friday and during the winter, though the increase was slight; but works passes were relatively prevalent on Friday. Correlation and regression show the association between numbers of one-day absences taken in two periods of time (each one year) to be marked (r = 0·5 to 0·7), unaffected by transforming to normal functions, and explicable on a linear hypothesis, but the value of r to increase as the periods of time increase and to decrease as the interval between the periods of time lengthens. Similar analyses for two-day absences show r = 0·25 to 0·55, acceptance of a linear hypothesis, and a suggestion that the value of r may increase as the periods of time increase and as the interval between them shortens. More limited examination shows corresponding values of r (for contiguous years) to be of the order 0·25 for medical passes, 0·60 for works passes, but > 0·80 for lateness. Values of r between each of these factors in turn for all possible pairs of days of the week are reasonably consistent and show r of the order 0·35 for one-day absences, 0·25 for medical passes, 0·40 for works passes, and 0·80 for lateness (values for two-day absences are irregular and in the range 0 to 0·4). The consistency of lateness experience over days and years is very marked, the correlations being among the highest recorded for any event involving human behaviour. The importance and application of the findings are briefly discussed; detailed consideration is reserved for the third and last paper. PMID:5448119

Effects of RF profile on precision of quantitative T2 mapping using dual-echo steady-state acquisition.

PubMed

Wu, Pei-Hsin; Cheng, Cheng-Chieh; Wu, Ming-Long; Chao, Tzu-Cheng; Chung, Hsiao-Wen; Huang, Teng-Yi

2014-01-01

The dual echo steady-state (DESS) sequence has been shown successful in achieving fast T2 mapping with good precision. Under-estimation of T2, however, becomes increasingly prominent as the flip angle decreases. In 3D DESS imaging, therefore, the derived T2 values would become a function of the slice location in the presence of non-ideal slice profile of the excitation RF pulse. Furthermore, the pattern of slice-dependent variation in T2 estimates is dependent on the RF pulse waveform. Multi-slice 2D DESS imaging provides better inter-slice consistency, but the signal intensity is subject to integrated effects of within-slice distribution of the actual flip angle. Consequently, T2 measured using 2D DESS is prone to inaccuracy even at the designated flip angle of 90°. In this study, both phantom and human experiments demonstrate the above phenomena in good agreement with model prediction. © 2013.

Development and Validation of RP-HPLC Method for the Estimation of Ivabradine Hydrochloride in Tablets

PubMed Central

Seerapu, Sunitha; Srinivasan, B. P.

2010-01-01

A simple, sensitive, precise and robust reverse–phase high-performance liquid chromatographic method for analysis of ivabradine hydrochloride in pharmaceutical formulations was developed and validated as per ICH guidelines. The separation was performed on SS Wakosil C18AR, 250×4.6 mm, 5 μm column with methanol:25 mM phosphate buffer (60:40 v/v), adjusted to pH 6.5 with orthophosphoric acid, added drop wise, as mobile phase. A well defined chromatographic peak of Ivabradine hydrochloride was exhibited with a retention time of 6.55±0.05 min and tailing factor of 1.14 at the flow rate of 0.8 ml/min and at ambient temperature, when monitored at 285 nm. The linear regression analysis data for calibration plots showed good linear relationship with R=0.9998 in the concentration range of 30-210 μg/ml. The method was validated for precision, recovery and robustness. Intra and Inter-day precision (% relative standard deviation) were always less than 2%. The method showed the mean % recovery of 99.00 and 98.55 % for Ivabrad and Inapure tablets, respectively. The proposed method has been successfully applied to the commercial tablets without any interference of excipients. PMID:21695008

A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids

PubMed Central

Zheng, Xiaojiao; Qiu, Yunping; Zhong, Wei; Baxter, Sarah; Su, Mingming; Li, Qiong; Xie, Guoxiang; Ore, Brandon M.; Qiao, Shanlei; Spencer, Melanie D.; Zeisel, Steven H.; Zhou, Zhanxiang; Zhao, Aihua; Jia, Wei

2013-01-01

Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography mass spectrometry (GC-MS) analysis. A one-step derivatization using 100 µL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency. The best extraction efficiency of the derivatized products was achieved by a two-step extraction with hexane. The method exhibited good derivatization efficiency and recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations (RSDs) of all targeted compounds showed good intra- and inter-day (within 7 days) precision (< 10%), and good stability (< 20%) within 4 days at room temperature (23–25 °C), or 7 days when stored at −20 °C. We applied our method to measure SCFA and BCAA levels in fecal samples from rats administrated with different diet. Both univariate and multivariate statistics analysis of the concentrations of these target metabolites could differentiate three groups with ethanol intervention and different oils in diet. This method was also successfully employed to determine SCFA and BCAA in the feces, plasma and urine from normal humans, providing important baseline information of the concentrations of these metabolites. This novel metabolic profile study has great potential for translational research. PMID:23997757

Evaluation of Beckman Coulter DxI 800 immunoassay system using clinically oriented performance goals.

PubMed

Akbas, Neval; Schryver, Patricia G; Algeciras-Schimnich, Alicia; Baumann, Nikola A; Block, Darci R; Budd, Jeffrey R; Gaston, S J Stephen; Klee, George G

2014-11-01

We evaluated the analytical performance of 24 immunoassays using the Beckman Coulter DxI 800 immunoassay systems at Mayo Clinic, Rochester, MN for trueness, precision, detection limits, linearity, and consistency (across instruments and reagent lots). Clinically oriented performance goals were defined using the following methods: trueness-published desirable accuracy limits, precision-published desirable biologic variation; detection limits - 0.1 percentile of patient test values, linearity - 50% of total error, and consistency-percentage test values crossing key decision points. Local data were collected for precision, linearity, and consistency. Data were provided by Beckman Coulter, Inc. for trueness and detection limits. All evaluated assays except total thyroxine were within the proposed goals for trueness. Most of the assays met the proposed goals for precision (86% of intra-assay results and 75% of inter-assay results). Five assays had more than 15% of the test results below the minimum detection limits. Carcinoembryonic antigen, total thyroxine and free triiodothyronine exceeded the proposed goals of ±6.3%, ±5% and ±5.7% for dilution linearity. All evaluated assays were within the proposed goals for instrument consistency. Lot-to-lot consistency results for cortisol, ferritin and total thyroxine exceeded the proposed goals of 3.3%, 11.4% and 7% at one medical decision level, while vitamin B12 exceeded the proposed goals of 5.2% and 3.8% at two decision levels. The Beckman Coulter DxI 800 immunoassay system meets most of these proposed goals, even though these clinically focused performance goals represent relatively stringent limits. Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

THE INTRA- AND INTER-RATER RELIABILITY OF THE SOCCER INJURY MOVEMENT SCREEN (SIMS).

PubMed

McCunn, Robert; Aus der Fünten, Karen; Govus, Andrew; Julian, Ross; Schimpchen, Jan; Meyer, Tim

2017-02-01

The growing volume of movement screening research reveals a belief among practitioners and researchers alike that movement quality may have an association with injury risk. However, existing movement screening tools have not considered the sport-specific movement and injury patterns relevant to soccer. The present study introduces the Soccer Injury Movement Screen (SIMS), which has been designed specifically for use within soccer. Furthermore, the purpose of the present study was to assess the intra- and inter-rater reliability of the SIMS and determine its suitability for use in further research. The study utilized a test-retest design to discern reliablility. Twenty-five (11 males, 14 females) healthy, recreationally active university students (age 25.5 ± 4.0 years, height 171 ± 9 cm, weight 64.7 ± 12.6 kg) agreed to participate. The SIMS contains five sub-tests: the anterior reach, single-leg deadlift, in-line lunge, single-leg hop for distance and tuck jump. Each movement was scored out of 10 points and summed to produce a composite score out of 50. The anterior reach and single-leg hop for distance were scored in real-time while the remaining tests were filmed and scored retrospectively. Three raters conducted the SIMS with each participant on three occasions separated by an average of three and a half days (minimum one day, maximum seven days). Rater 1 re-scored the filmed movements for all participants on all occasions six months later to establish the 'pure' intra-rater (intra-occasion) reliability for those movements. Intraclass correlation coefficient (ICC) values for intra- and inter-rater composite score reliability ranged from 0.66-0.72 and 0.79-0.86 respectively. Weighted kappa values representing the intra- and inter-rater reliability of the individual sub-tests ranged from 0.35-0.91 indicating fair to almost perfect agreement. Establishing the reliability of the SIMS is a prerequisite for further research seeking to investigate the relationship between test score and subsequent injury. The present results indicate acceptable reliability for this purpose; however, room for further development of the intra-rater reliability exists for some of the individual sub-tests. 2b.

THE INTRA- AND INTER-RATER RELIABILITY OF THE SOCCER INJURY MOVEMENT SCREEN (SIMS)

PubMed Central

aus der Fünten, Karen; Govus, Andrew; Julian, Ross; Schimpchen, Jan; Meyer, Tim

2017-01-01

Background/purpose The growing volume of movement screening research reveals a belief among practitioners and researchers alike that movement quality may have an association with injury risk. However, existing movement screening tools have not considered the sport-specific movement and injury patterns relevant to soccer. The present study introduces the Soccer Injury Movement Screen (SIMS), which has been designed specifically for use within soccer. Furthermore, the purpose of the present study was to assess the intra- and inter-rater reliability of the SIMS and determine its suitability for use in further research. Methods The study utilized a test-retest design to discern reliablility. Twenty-five (11 males, 14 females) healthy, recreationally active university students (age 25.5 ± 4.0 years, height 171 ± 9 cm, weight 64.7 ± 12.6 kg) agreed to participate. The SIMS contains five sub-tests: the anterior reach, single-leg deadlift, in-line lunge, single-leg hop for distance and tuck jump. Each movement was scored out of 10 points and summed to produce a composite score out of 50. The anterior reach and single-leg hop for distance were scored in real-time while the remaining tests were filmed and scored retrospectively. Three raters conducted the SIMS with each participant on three occasions separated by an average of three and a half days (minimum one day, maximum seven days). Rater 1 re-scored the filmed movements for all participants on all occasions six months later to establish the ‘pure’ intra-rater (intra-occasion) reliability for those movements. Results Intraclass correlation coefficient (ICC) values for intra- and inter-rater composite score reliability ranged from 0.66-0.72 and 0.79-0.86 respectively. Weighted kappa values representing the intra- and inter-rater reliability of the individual sub-tests ranged from 0.35-0.91 indicating fair to almost perfect agreement. Conclusions Establishing the reliability of the SIMS is a prerequisite for further research seeking to investigate the relationship between test score and subsequent injury. The present results indicate acceptable reliability for this purpose; however, room for further development of the intra-rater reliability exists for some of the individual sub-tests. Level of evidence 2b PMID:28217416

Airborne Precision Spacing: A Trajectory-based Approach to Improve Terminal Area Operations

NASA Technical Reports Server (NTRS)

Barmore, Bryan

2006-01-01

Airborne Precision Spacing has been developed by the National Aeronautics and Space Administration (NASA) over the past seven years as an attempt to benefit from the capabilities of the flight deck to precisely space their aircraft relative to another aircraft. This development has leveraged decades of work on improving terminal area operations, especially the arrival phase. With APS operations, the air traffic controller instructs the participating aircraft to achieve an assigned inter-arrival spacing interval at the runway threshold, relative to another aircraft. The flight crew then uses airborne automation to manage the aircraft s speed to achieve the goal. The spacing tool is designed to keep the speed within acceptable operational limits, promote system-wide stability, and meet the assigned goal. This reallocation of tasks with the controller issuing strategic goals and the flight crew managing the tactical achievement of those goals has been shown to be feasible through simulation and flight test. A precision of plus or minus 2-3 seconds is generally achievable. Simulations of long strings of arriving traffic show no signs of instabilities or compression waves. Subject pilots have rated the workload to be similar to current-day operations and eye-tracking data substantiate this result. This paper will present a high-level review of research results over the past seven years from a variety of tests and experiments. The results will focus on the precision and accuracy achievable, flow stability and some major sources of uncertainty. The paper also includes a summary of the flight crew s procedures and interface and a brief concept overview.

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

PubMed

Yao, Tian; Yao, Shun

2017-01-20

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

Ion-Pair Extractive Spectrophotometric Assay of Terbinafine Hydrochloride in Pharmaceuticals and Spiked Urine Using Bromocresol Purple

NASA Astrophysics Data System (ADS)

Salem Qarah, N. A.; Basavaiah, K.; Swamy, N.

2016-09-01

Two simple, rapid, selective, and sensitive methods were developed and validated for the determination of terbinafi ne hydrochloride (TBH) in pharmaceuticals and urine. The fi rst method (method A) is based on the formation of a yellow ion-pair complex of TBH and bromocresol purple (BCP), a sulfonephthalein dye, in Walpole buffer of pH 3.61, which was extracted into chloroform and investigated at 420 nm. For the second method (method B) the drug-dye ion-pair was broken in alkaline KOH medium, and the resulting free dye color was measured at 610 nm. All variables were studied to optimize the reaction conditions. The regression analysis of Beer's law plots showed good correlation in the concentration ranges of 1-10 and 0.1-2.0 μg/mL for method A and method B, respectively. Molar absorptivity values were 2.99 × 104, and 1.51×105 L/(mol × cm) for measurements by these methods. The methods were also validated for limits of detection (LOD) and quantifi cation (LOQ), intra-day and inter-day accuracy and precision, selectivity, robustness and ruggedness. The composition of the ion-pair (drug-dye) used in the method A was found to be 1:1 by both mole-ratio and Job's methods. The developed methods were applied to tablets, and the results were in good agreement with the label claim and those of the reference method. Because of its high sensitivity, method A was applied to spiked human urine with percent recoveries in the range 96.58-107.3 and a standard deviation <2%.

Preconcentration and Determination of Trace Vanadium(V) in Beverages by Combination of Ultrasound Assisted-cloud Point Extraction with Spectrophotometry.

PubMed

Kartal Temel, Nuket; Gürkan, Ramazan

2018-03-01

A novel ultrasound assisted-cloud point extraction method was developed for preconcentration and determination of V(V) in beverage samples. After complexation by pyrogallol in presence of safranin T at pH 6.0, V(V) ions as ternary complex are extracted into the micellar phase of Triton X-114. The complex was monitored at 533 nm by spectrophotometry. The matrix effect on the recovery of V(V) from the spiked samples at 50 μg L-1 was evaluated. In optimized conditions, the limits of detection and quantification of the method, respectively, was 0.58 and 1.93 μg L-1 in linear range of 2-500 μg L-1 with sensitivity enhancement and preconcentration factors of 47.7 and 40 for preconcentration from 15 mL of sample solution. The recoveries from spiked samples were in range of 93.8-103.2% with a relative standard deviation ranging from 2.6% to 4.1% (25, 100 and 250 μg L-1, n: 5). The accuracy was verified by analysis of two certified samples, and the results were in a good agreement with the certified values. The intra-day and inter-day precision were tested by reproducibility (as 3.3-3.4%) and repeatability (as 3.4-4.1%) analysis for five replicate measurements of V(V) in quality control samples spiked with 5, 10 and 15 μg L-1. Trace V(V) contents of the selected beverage samples by the developed method were successfully determined.

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

PubMed

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

2008-11-01

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

Quantification of ethanol in plasma by electrochemical detection with an unmodified screen printed carbon electrode

NASA Astrophysics Data System (ADS)

Tian, Gang; Zhang, Xiao-Qing; Zhu, Ming-Song; Zhang, Zhong; Shi, Zheng-Hu; Ding, Min

2016-03-01

Simple, rapid and accurate detection of ethanol concentration in blood is very crucial in the diagnosis and management of potential acute ethanol intoxication patients. A novel electrochemical detection method was developed for the quantification of ethanol in human plasma with disposable unmodified screen-printed carbon electrode (SPCE) without sample preparation procedure. Ethanol was detected indirectly by the reaction product of ethanol dehydrogenase (ADH) and cofactor nicotinamide adenine dinucleotide (NAD+). Method validation indicated good quantitation precisions with intra-day and inter-day relative standard deviations of ≤9.4% and 8.0%, respectively. Ethanol concentration in plasma is linear ranging from 0.10 to 3.20 mg/mL, and the detection limit is 40.0 μg/mL (S/N > 3). The method shows satisfactory correlation with the reference method of headspace gas chromatography in twenty human plasma samples (correlation coefficient 0.9311). The proposed method could be applied to diagnose acute ethanol toxicity or ethanol-related death.

Quantification of ethanol in plasma by electrochemical detection with an unmodified screen printed carbon electrode

PubMed Central

Tian, Gang; Zhang, Xiao-Qing; Zhu, Ming-Song; Zhang, Zhong; Shi, Zheng-Hu; Ding, Min

2016-01-01

Simple, rapid and accurate detection of ethanol concentration in blood is very crucial in the diagnosis and management of potential acute ethanol intoxication patients. A novel electrochemical detection method was developed for the quantification of ethanol in human plasma with disposable unmodified screen-printed carbon electrode (SPCE) without sample preparation procedure. Ethanol was detected indirectly by the reaction product of ethanol dehydrogenase (ADH) and cofactor nicotinamide adenine dinucleotide (NAD+). Method validation indicated good quantitation precisions with intra-day and inter-day relative standard deviations of ≤9.4% and 8.0%, respectively. Ethanol concentration in plasma is linear ranging from 0.10 to 3.20 mg/mL, and the detection limit is 40.0 μg/mL (S/N > 3). The method shows satisfactory correlation with the reference method of headspace gas chromatography in twenty human plasma samples (correlation coefficient 0.9311). The proposed method could be applied to diagnose acute ethanol toxicity or ethanol-related death. PMID:27006081

The role of the atrial electromechanical delay in predicting atrial fibrillation in beta-thalassemia major patients.

PubMed

Rago, Anna; Russo, Vincenzo; Papa, Andrea Antonio; Ciardiello, Carmine; Pannone, Bruno; Mayer, Maria Carolina; Cimmino, Giovanni; Nigro, Gerardo

2017-03-01

Paroxysmal atrial tachyarrhythmias frequently occur in beta-thalassemia major (β-TM) patients. The aim of the current study was to evaluate the atrial electromechanical delay (AEMD) in a large β-TM population with normal cardiac function and its relationship to atrial fibrillation (AF) onset. Eighty β-TM patients (44 men, 36 women), with a mean age of 36.2 ± 11.1 years, and 80 healthy subjects used as controls, matched for age and gender, were studied for the occurrence of AF during a 5-year follow-up, through 30-day external loop recorder (ELR) monitoring performed every 6 months. Intra-AEMD and inter-AEMD of both atria were measured through tissue Doppler echocardiography. P-wave dispersion (PD) was carefully measured using 12-lead electrocardiogram (ECG). Compared to the healthy control group, the β-TM patients showed a statistically significant increase in inter-AEMD, intra-left AEMD, maximum P-wave duration, and PD. Dividing the β-TM group into two subgroups (patients with or without AF), the inter-AEMD, intra-left AEMD, maximum P-wave duration, and PD were significantly higher in the subgroup with AF compared to the subgroup without AF. There were significant good correlations of intra-left AEMD and inter-AEMD with PD. A cut-off value of 40.1 ms for intra-left AEMD had a sensitivity of 76.2% and a specificity of 97.5% in identifying β-TM patients with AF risk. A cut-off value of 44.8 ms for inter-AEMD had a sensitivity of 81.2% and a specificity of 98.7% in identifying this category of patients. Our results showed that the echocardiographic atrial electromechanical delay indices (intra-left and inter-AEMD) and the PD were significantly increased in β-TM subjects with normal cardiac function. PD and AEMD represent non-invasive, inexpensive, useful, and simple parameters to assess the AF risk in β-TM patients.

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.

Determination of cocaine, benzoylecgonine, cocaethylene and norcocaine in human hair using solid-phase extraction and liquid chromatography with tandem mass spectrometric detection.

PubMed

Moore, Christine; Coulter, Cynthia; Crompton, Katherine

2007-11-15

A quantitative analytical procedure for the determination of cocaine, benzoylecgonine and cocaethylene and norcocaine in hair has been developed and validated. The hair samples were washed, incubated, and any drugs present were quantified using mixed mode solid-phase extraction and liquid chromatography with tandem mass spectrometric detection in positive atmospheric pressure chemical ionization mode. For confirmation, two transitions were monitored and one ion ratio was determined, which was within 20% of that of the known calibration standards. The monitoring of the qualifying transition and requirement for its presence within a specific ratio to the primary ion limited the sensitivity of the assay, particularly for benzoylecgonine, however, the additional confidence in the final result as well as forensic defensibility were considered to be of greater importance. Even with simultaneous monitoring, the concentrations proposed by the United States Federal guidelines for hair analysis were achieved. The limits of quantitation were 50 pg/mg; the limit of detection was 25 pg/mg. The intra-day precision of the assays at 100 pg/mg (n=5) was 1.3%, 8.1%, 0.8% and 0.4%; inter-day precision 4.8%, 9.2%, 15.7% and 12.6% (n=10) for cocaine, benzoylecgonine, cocaethylene and norcocaine, respectively. The methods were applied to both proficiency specimens and to samples obtained during research studies in the USA.

Verification of Bioanalytical Method for Quantification of Exogenous Insulin (Insulin Aspart) by the Analyser Advia Centaur® XP.

PubMed

Mihailov, Rossen; Stoeva, Dilyana; Pencheva, Blagovesta; Pentchev, Eugeni

2018-03-01

In a number of cases the monitoring of patients with type I diabetes mellitus requires measurement of the exogenous insulin levels. For the purpose of a clinical investigation of the efficacy of a medical device for application of exogenous insulin aspart, a verification of the method for measurement of this synthetic analogue of the hormone was needed. The information in the available medical literature for the measurement of the different exogenous insulin analogs is insufficient. Thus, verification was required to be in compliance with the active standards in Republic of Bulgaria. A manufactured method developed for ADVIA Centaur XP Immunoassay, Siemens Healthcare, was used which we verified using standard solutions and a patient serum pool by adding the appropriate quantity exogenous insulin aspart. The method was verified in accordance with the bioanalytical method verification criteria and regulatory requirements for using a standard method: CLIA chemiluminescence immunoassay ADVIA Centaur® XP. The following parameters are determined and monitored: intra-day precision and accuracy, inter-day precision and accuracy, limit of detection and lower limit of quantification, linearity, analytical recovery. The routine application of the method for measurement of immunoreactive insulin using the analyzer ADVIA Centaur® XP is directed to the measurement of endogenous insulin. The method is applicable for measuring different types of exogenous insulin, including insulin aspart.

A novel freeze-dried storage and preparation method for the determination of mycophenolic acid in plasma by high-performance liquid chromatography.

PubMed

Wang, Lei; Qiang, Wei; Li, Ying; Cheng, Zeneng; Xie, Mengmeng

2017-09-01

Plasma samples were conventionally stored at freezing conditions until the time of detection. Such a technique, when carried out over an extended period, is energy consuming; in addition, preparation and transportation of stored samples is inconvenient. In this study, a freeze-dried storage and preparation method was proposed to determine the presence of mycophenolic acid (MPA) in plasma. Fresh plasma samples were freeze-dried using a device, and then stored at ambient temperature. After the stored samples were soaked with methanol spiked with the internal standard, high-performance liquid chromatography was conducted to detect MPA. The proposed method was demonstrated to be precise and accurate over the linear range of 0.5-50 μg mL -1 , with both intra- and inter-day precision being <7% and biases <10%. The freeze-dried samples were stable at ambient temperature for at least 40 days. This method was also successfully applied to the pharmacokinetic study of MPA in healthy volunteers. Pharmacokinetic parameters, such as maximum plasma concentration, time point of maximum plasma concentration and elimination half-life, among others, were consistent with the results in the published study. This proposed technique was proved to be simple, reproducible and energy saving. This approach could also simplify the storage and analysis of samples in clinical and scientific drug research. Copyright © 2017 John Wiley & Sons, Ltd.

Determination of itopride hydrochloride in human plasma by RP-HPLC with fluorescence detection and its use in bioequivalence study.

PubMed

Ma, Jing; Yuan, Li-Hua; Ding, Mei-Juan; Zhang, Jun; Zhang, Qing; Xu, Qun-Wei; Zhou, Xue-Min

2009-03-01

A sensitive, selective and simple method using a precipitation of protein with 10% perchloric acid, followed by high-performance liquid chromatography (HPLC) with fluorescence detection was developed for the determination of itopride hydrochloride in human plasma, using levofloxacin as the internal standard (IS). Chromatographic separation was obtained within 7.0 min using a reverse phase Hypersil BDS C(18) (250 mm x 4.6 mm, 5 microm) column and an isocratic mobile phase, constituting of a mixture of 0.1 mol/l ammonium acetate-methanol (30:70, v/v) flowing at 1.1 ml/min. The excitation and emission wavelengths were set at 304 and 344 nm, respectively. The method was validated over the concentration range of 5 ng/ml to 1000.0 ng/ml. The lower limit of quantitation (LLOQ) was 5 ng/ml. The extractive recovery of itopride hydrochloride from the biological matrix was more than 80.77%. The intra-day accuracy of the drug containing serum samples was more than 82.94% with a precision of 2.81-4.37%. The inter-day accuracy was 82.91% or more, with a precision of 6.89-9.54%. The limit we have used (70-143%) is based on the local regulatory authority (SFDA). The developed method was validated and successfully applied to bioequivalence studies of itopride hydrochloride in healthy male volunteers.

Pelvis and lower limb anatomical landmark calibration precision and its propagation to bone geometry and joint angles.

PubMed

della Croce, U; Cappozzo, A; Kerrigan, D C

1999-03-01

Human movement analysis using stereophotogrammetry is based on the reconstruction of the instantaneous laboratory position of selected bony anatomical landmarks (AL). For this purpose, knowledge of an AL's position in relevant bone-embedded frames is required. Because ALs are not points but relatively large and curved areas, their identification by palpation or other means is subject to both intra- and inter-examiner variability. In addition, the local position of ALs, as reconstructed using an ad hoc experimental procedure (AL calibration), is affected by photogrammetric errors. The intra- and inter-examiner precision with which local positions of pelvis and lower limb palpable bony ALs can be identified and reconstructed were experimentally assessed. Six examiners and two subjects participated in the study. Intra- and inter-examiner precision (RMS distance from the mean position) resulted in the range 6-21 mm and 13-25 mm, respectively. Propagation of the imprecision of ALs to the orientation of bone-embedded anatomical frames and to hip, knee and ankle joint angles was assessed. Results showed that this imprecision may cause distortion in joint angle against time functions to the extent that information relative to angular movements in the range of 10 degrees or lower may be concealed. Bone geometry parameters estimated using the same data showed that the relevant precision does not allow for reliable bone geometry description. These findings, together with those relative to skin movement artefacts reported elsewhere, assist the human movement analyst's consciousness of the possible limitations involved in 3D movement analysis using stereophotogrammetry and call for improvements of the relevant experimental protocols.

Short-term market reaction after trading halts in Chinese stock market

NASA Astrophysics Data System (ADS)

Xu, Hai-Chuan; Zhang, Wei; Liu, Yi-Fang

2014-05-01

In this paper, we study the dynamics of absolute return, trading volume and bid-ask spread after the trading halts using high-frequency data from the Shanghai Stock Exchange. We deal with all three types of trading halts, namely intraday halts, one-day halts and inter-day halts, of 203 stocks in Shanghai Stock Exchange from August 2009 to 2011. We find that absolute return, trading volume, and in case of bid-ask spread around intraday halts share the same pattern with a sharp peak and a power law relaxation after that. While for different types of trading halts, the peaks’ height and the relaxation exponents are different. From the perspective of halt reasons or halt durations, the relaxation exponents of absolute return after inter-day halts are larger than those after intraday halts and one-day halts, which implies that inter-day halts are most effective. From the perspective of price trends, the relaxation exponents of excess absolute return and excess volume for positive events are larger than those for negative events in case of intraday halts and one-day halts, implying that positive events are more effective than negative events for intraday halts and one-day halts. In contrast, negative events are more effective than positive events for inter-day halts.

Automated measurement of carbohydrate-deficient transferrin using the Bio-Rad %CDT by the HPLC test on a Variant HPLC system: evaluation and comparison with other routine procedures.

PubMed

Schellenberg, François; Mennetrey, Louise; Girre, Catherine; Nalpas, Bertrand; Pagès, Jean Christophe

2008-01-01

In this study, we evaluated the new %CDT by the HPLC method (Bio-Rad, Germany) on a Varianttrade mark HPLC system (Bio-Rad), checked the correlation with well-known methods and calculated the diagnostic value of the test. Intra-run and day-to-day precision values were calculated for samples with extreme serum transferrin concentrations, high trisialotransferrin and interfering conditions (haemolysed, lactescent and icteric samples). The method was compared with two routine procedures, the %CDT TIA (Bio-Rad, Hercules, CA, USA) and the Capillarystrade mark CDT (Sebia, France). A total of 350 clinical sera samples were used for a case-control study. Precision values were better in high CDT and medium CDT pools than in low CDT pools. The serum transferrin concentration had no effect on CDT measurement, except in samples with serum transferrin <1 g/L. Haemolysis was the only interfering situation. The method showed high correlation (r(2) > 0.95) with the two other methods (%CDT TIA and CZE %CDT). The global predictive value of the test was >0.90 at 1.9% cut-off. These results demonstrate that the %CDT by the HPLC test is suitable for CDT routine measurement; the results from the high-throughput Varianttrade mark system are well correlated with other methods and are of high diagnostic value.

Immunoassays for the measurement of IGF-II, IGFBP-2 and -3, and ICTP as indirect biomarkers of recombinant human growth hormone misuse in sport. Values in selected population of athletes.

PubMed

Abellan, Rosario; Ventura, Rosa; Palmi, Ilaria; di Carlo, Simonetta; Bacosi, Antonella; Bellver, Montse; Olive, Ramon; Pascual, Jose Antonio; Pacifici, Roberta; Segura, Jordi; Zuccaro, Piergiorgio; Pichini, Simona

2008-11-04

Insulin-like growth factor-II (IGF-II), insulin-like growth factor binding proteins (IGFBPs) -2 and -3 and C-terminal telopeptide of type I collagen (ICTP) have been proposed, among others, as indirect biomarkers of the recombinant human growth hormone misuse in sport. An extended intra- and inter-laboratory validation of commercially available immunoassays for biomarkers detection was performed. ELISA assays for total IGF-II, IGFBP-2 and IGFBP-3 (IGF-II/ELISA1: DSLabs, IGFBP-2/ELISA2: Biosource, and IGFBP-3/ELISA3: BioSource) and an EIA assay for ICTP (ICTP/EIA: Orion Diagnostica) were evaluated. The inter- and intra-laboratory precision values were acceptable for all evaluated assays (maximum imprecision of 30% and 66% were found only for the lowest quality control samples of IGF-II and IGFBP-3). Correct accuracy was obtained for all inter-laboratory immunoassays and for IGFBP-2 intra-laboratory immunoassay. The range of concentrations found in serum samples under investigation was always covered by the calibration curves of the studied immunoassays. However, 11% and 15% of the samples felt below the estimated LOQ for IGF-II and ICTP, respectively, in the zone where lower precision was obtained. Although the majority of evaluated assays showed an overall reliability not always suitable for antidoping control analysis, relatively high concordances between laboratory results were obtained for all assays. Evaluated immunoassays were used to measure serum concentrations of IGF-II, IGFBP-2 and -3 and ICTP in elite athletes of various sport disciplines at different moments of the training season; in recreational athletes at baseline conditions and finally in sedentary individuals. Serum IGF-II was statistically higher both in recreational and elite athletes compared to sedentary individuals. Elite athletes showed lower IGFBP-2 and higher IGFBP-3 concentration with respect to recreational athletes and sedentary people. Among elite athletes, serum IGFBP-3 (synchronized swimming), and ICTP (rhythmic gymnastics) concentrations were sport-dependent. Over the training season, within athlete variability was observed for IGFBP-2 in case of taekwondo and IGFBP-2 and -3 in case of weightlifting. Variations due to those aspects should be taken in careful consideration in the hypothesis of setting reference concentration ranges for doping detection.

Quantitation of itopride in human serum by high-performance liquid chromatography with fluorescence detection and its application to a bioequivalence study.

PubMed

Singh, Sonu Sundd; Jain, Manish; Sharma, Kuldeep; Shah, Bhavin; Vyas, Meghna; Thakkar, Purav; Shah, Ruchy; Singh, Shriprakash; Lohray, Brajbhushan

2005-04-25

A new method was developed for determination of itopride in human serum by reversed phase high-performance liquid chromatography (HPLC) with fluorescence detection (excitation at 291 nm and emission at 342 nm). The method employed one-step extraction of itopride from serum matrix with a mixture of tert-butyl methyl ether and dichloromethane (70:30, v/v) using etoricoxib as an internal standard. Chromatographic separation was obtained within 12.0 min using a reverse phase YMC-Pack AM ODS column (250 mm x 4.6 mm, 5 microm) and an isocratic mobile phase constituting of a mixture of 0.05% tri-fluoro acetic acid in water and acetonitrile (75:25, v/v) flowing at a flow rate of 1.0 ml/min. The method was linear in the range of 14.0 ng/ml to 1000.0 ng/ml. The lower limit of quantitation (LLOQ) was 14.0 ng/ml. Average recovery of itopride and the internal standard from the biological matrix was more than 66.04 and 64.57%, respectively. The inter-day accuracy of the drug containing serum samples was more than 97.81% with a precision of 2.31-3.68%. The intra-day accuracy was 96.91% or more with a precision of 5.17-9.50%. Serum samples containing itopride were stable for 180.0 days at -70+/-5 degrees C and for 24.0 h at ambient temperature (25+/-5 degrees C). The method was successfully applied to the bioequivalence study of itopride in healthy, male human subjects.

Inter-observer and intra-observer agreement between embryologists during selection of a single Day 5 embryo for transfer: a multicenter study.

PubMed

Storr, Ashleigh; Venetis, Christos A; Cooke, Simon; Kilani, Suha; Ledger, William

2017-02-01

What is the inter-observer and intra-observer agreement between embryologists when selecting a single Day 5 embryo for transfer? The inter-observer and intra-observer agreement between embryologists when selecting a single Day 5 embryo for transfer was generally good, although not optimal, even among experienced embryologists. Previous research on the morphological assessment of early stage (two pronuclei to Day 3) embryos has shown varying levels of inter-observer and intra-observer agreement. However, single blastocyst transfer is now becoming increasingly popular and there are no published data that assess inter-observer and intra-observer agreement when selecting a single embryo for Day 5 transfer. This was a prospective study involving 10 embryologists working at five different IVF clinics within a single organization between July 2013 and November 2015. The top 10 embryologists were selected based on their yearly Quality Assurance Program scores for blastocyst grading and were asked to morphologically grade all Day 5 embryos and choose a single embryo for transfer in a survey of 100 cases using 2D images. A total of 1000 decisions were therefore assessed. For each case, Day 5 images were shown, followed by a Day 3 and Day 5 image of the same embryo. Subgroup analyses were also performed based on the following characteristics of embryologists: the level of clinical embryology experience in the laboratory; amount of research experience; number of days per week spent grading embryos. The agreement between these embryologists and the one that scored the embryos on the actual day of transfer was also evaluated. Inter-observer and intra-observer variability was assessed using the kappa coefficient to evaluate the extent of agreement. This study showed that all 10 embryologists agreed on the embryo chosen for transfer in 50 out of 100 cases. In 93 out of 100 cases, at least 6 out of the 10 embryologists agreed. The inter-observer and intra-observer agreement among embryologists when selecting a single Day 5 embryo for transfer was generally good as assessed by the kappa scores (kappa = 0.734, 95% CI: 0.665-0.791 and 0.759, 95% CI: 0.622-0.833, respectively). The subgroup analyses did not substantially alter the inter-observer and intra-observer agreement among embryologists. The agreement when Day 3 images were included alongside Day 5 images of the same embryos resulted in a change of mind at least three times by each embryologist (on average for <10% of cases) and resulted in a small decrease in inter-observer and intra-observer agreement between embryologists (kappa = 0.676, 95% CI: 0.617-0.724 and 0.752, 95% CI: 0.656-808, respectively).The assessment of the inter-observer agreement with regard to morphological grading of Day 5 embryos showed only a fair-to-moderate agreement, which was observed across all subgroup analyses. The highest overall kappa coefficient was seen for the grading of the developmental stage of an embryo (0.513; 95% CI: 0.492-0.538). The findings were similar when the individual embryologists were compared with the embryologist who made the morphological assessments of the available embryos on the actual day of transfer. All embryologists had already completed their training and were working under one organization with similar policies between the five clinics. Therefore, the inter-observer agreement might not be as high between embryologists working in clinics with different policies or with different levels of training. The generally good, although not optimal uniformity between participating embryologists when selecting a Day 5 embryo for transfer, as well as, the surprisingly low agreement when morphologically grading Day 5 embryos could be improved, potentially resulting in increased pregnancy rates. Future studies need to be directed toward technologies that can help achieve this. None declared. Not applicable. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Liquid chromatographic determination of 9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one in human plasma with fluorescence detection.

PubMed

Cheng, H; Pittman, K A; Dandekar, K A

1987-12-01

A simple and sensitive assay for quantitating 9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one (1; BMY 26517) in human plasma was developed using high-performance liquid chromatography with fluorescence detection. The method involves precipitation of protein and reversed-phase chromatography. The method is linear in the range of 4.3-429 ng/mL of 1, and the limit of detection is 0.4 ng/mL. The day-to-day precision values of this method at 25.7 and 386 ng/mL are 2.1 and 2.6%, respectively. The day-to-day accuracy values at these concentrations are 99.7 and 99.8%, respectively. The recovery of 1 is 98.3%.

A fuzzy Bayesian network approach to quantify the human behaviour during an evacuation

NASA Astrophysics Data System (ADS)

Ramli, Nurulhuda; Ghani, Noraida Abdul; Ahmad, Nazihah

2016-06-01

Bayesian Network (BN) has been regarded as a successful representation of inter-relationship of factors affecting human behavior during an emergency. This paper is an extension of earlier work of quantifying the variables involved in the BN model of human behavior during an evacuation using a well-known direct probability elicitation technique. To overcome judgment bias and reduce the expert's burden in providing precise probability values, a new approach for the elicitation technique is required. This study proposes a new fuzzy BN approach for quantifying human behavior during an evacuation. Three major phases of methodology are involved, namely 1) development of qualitative model representing human factors during an evacuation, 2) quantification of BN model using fuzzy probability and 3) inferencing and interpreting the BN result. A case study of three inter-dependencies of human evacuation factors such as danger assessment ability, information about the threat and stressful conditions are used to illustrate the application of the proposed method. This approach will serve as an alternative to the conventional probability elicitation technique in understanding the human behavior during an evacuation.

Supercritical fluid extraction of 13-cis retinoic acid and its photoisomers from selected pharmaceutical dosage forms.

PubMed

Simmons, B R; Chukwumerije, O; Stewart, J T

1997-11-01

13-Cis retinoic acid (Accutane) was extracted from a cream, gel, capsule and beadlet dosage from using supercritical carbon dioxide modified with 5% methanol as the mobile phase. The pump pressure and the extraction chamber and restrictor temperature were experimentally optimized at 325 atm and 45 degrees C, respectively. A 2.5-min static and 5-min dynamic extraction time were used. The supercritical fluid extraction (SFE) eluent was trapped in methanol, injected into the high-performance liquid chromatographic (HPLC) system, and quantitated by ultraviolet detection at 360 nm. Application of the SFE method to spiked placebo dosage forms gave 13-cis retinoic acid recoveries of 98.8, 98.9, 98.8 and 100% for the cream, gel, capsule and beadlet, respectively, with R.S.D.s in the range 0.6-0.9% (n = 4). Inter-day percent error and precision of the extraction were 1.1-2.0 and 0.2-2.4% (n = 3), respectively, and intra-day percent error and precision were 1.0-3.0 and 0.3-2.1% (n = 8), respectively. Percent error and precision data for spiked celite samples in the 0.05-1.0 microgram ml-1 range were 0.59-4.75 and 1.8-2.1% (n = 3), respectively. The extraction method was applied to commercial 13-cis retinoic acid dosage forms and the results compared to unextracted samples. Linear regression analysis of concentration versus peak height gave a correlation coefficient of 0.9991 with a slope of 7.468 and a y-intercept of 0.1923. The percent error and precision data were 1.3-5.3 and 0.2-1.5% (n = 4), respectively. The photoisomers of 13-cis retinoic acid were also extracted with the method and recoveries of 90.4-92.4% with R.S.D.s of 1.5-3.4% were obtained (n = 4).

Suitability of 1-hexyl-3-methylimidazolium ionic liquids for the analysis of pharmaceutical formulations containing tricyclic antidepressants.

PubMed

Calabuig-Hernández, S; Peris-García, E; García-Alvarez-Coque, M C; Ruiz-Angel, M J

2018-07-20

The reversed-phase chromatographic behaviour of six tricyclic antidepressants (amitryptiline, clomipramine, doxepin, imipramine, nortryptiline and maprotiline) was examined in this work with acetonitrile-water mobile phases, in the absence and presence of the ionic liquids 1-hexyl-3-methylimidazolium chloride and 1-hexyl-3-methylimidazolium tetrafluoroborate, which have interesting features for the separation of basic compounds, in terms of peak shape combined with reduced retention. Tricyclic antidepressants are low polarity drugs that strongly associate to the alkyl chains of conventional stationary phases. They are also positively charged in the usual working pH range (2-8) in reversed-phase liquid chromatography, due to their strong basic character. In consequence, they may interact with the residual ionised silanols present in conventional silica-based stationary phases, which is translated in stronger retention, and tailed and broad peaks. A simple chromatographic procedure for the control of tricyclic antidepressants in pharmaceutical formulations was developed using a C8 column and a mobile phase containing 30% acetonitrile/10 mM 1-hexyl-3-methylimidazolium chloride at pH 3, with UV detection. Intra- and inter-day precisions were usually below +1.0%, and intra- and inter-day bias (trueness) ranged between ‒2.1% and +2.4%, and between ‒3.0% and +2.3%, respectively. Sample preparation was simple and only required solubilisation and filtration previous to injection. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct tandem mass spectrometry for the simultaneous assay of opioids, cocaine and metabolites in dried urine spots.

PubMed

Otero-Fernández, Mara; Cocho, José Ángel; Tabernero, María Jesús; Bermejo, Ana María; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

2013-06-19

A micro-analytical method based on spotting urine samples (20μL) onto blood/urine spot collection cards followed by air-drying and extraction (dried urine spot, DUS) was developed and validated for the screening/confirmation assay of morphine, 6-methylacetylmorphine (6-MAM), codeine, cocaine and benzoylecgonine (BZE). Acetonitrile (3 mL) was found to be a useful solvent for target extraction from DUSs under an orbital-horizontal stirring at 180 rpm for 10 min. Determinations were performed by direct electrospray ionization tandem mass spectrometry (ESI-MS/MS) under positive electrospray ionization conditions, and by using multiple reaction monitoring (MRM) with one precursor ion/product ion transition for the identification and quantification (deuterated analogs of each target as internal standards) of each analyte. The limits of detection of the method were 0.26, 0.94, 1.5, 1.1, and 2.0 ng mL(-1), for cocaine, BZE, codeine, morphine and 6-MAM, respectively; whereas, relative standard deviations of intra- and inter-day precision were lower than 8 and 11%, respectively, and intra- and inter-day analytical recoveries ranged from 94±4 to 105±3%. The small volume of urine required (20 μL), combined with the simplicity of the analytical technique makes it a useful procedure for screening/quantifying drugs of abuse. The method was successfully applied to the analysis of urine from polydrug abusers. Copyright © 2013 Elsevier B.V. All rights reserved.

Stereoselective method to quantify bupropion and its three major metabolites, hydroxybupropion, erythro-dihydrobupropion, and threo-dihydrobupropion using HPLC-MS/MS.

PubMed

Masters, Andrea R; McCoy, Michael; Jones, David R; Desta, Zeruesenay

2016-03-15

Bupropion metabolites formed via oxidation and reduction exhibit pharmacological activity, but little is known regarding their stereoselective disposition. A novel stereoselective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to separate and quantify enantiomers of bupropion, 4-hydroxybupropion, and erythro- and threo-dihydrobupropion. Liquid-liquid extraction was implemented to extract all analytes from 50 μL human plasma. Acetaminophen (APAP) was used as an internal standard. The analytes were separated on a Lux 3 μ Cellulose-3 250×4.6 mm column by methanol: acetonitrile: ammonium bicarbonate: ammonium hydroxide gradient elution and monitored using an ABSciex 5500 QTRAP triple-quadrupole mass spectrometer equipped with electrospray ionization probe in positive mode. Extraction efficiency for all analytes was ≥70%. The stability at a single non-extracted concentration for over 48 h at ambient temperature resulted in less than 9.8% variability for all analytes. The limit of quantification (LOQ) for enantiomers of bupropion and 4-hydroxybupropion was 0.3 ng/mL, while the LOQ for enantiomers of erythro- and threo-hydrobupropion was 0.15 ng/mL. The intra-day precision and accuracy estimates for enantiomers of bupropion and its metabolites ranged from 3.4% to 15.4% and from 80.6% to 97.8%, respectively, while the inter-day precision and accuracy ranged from 6.1% to 19.9% and from 88.5% to 99.9%, respectively. The current method was successfully implemented to determine the stereoselective pharmacokinetics of bupropion and its metabolites in 3 healthy volunteers administered a single 100mg oral dose of racemic bupropion. This novel, accurate, and precise HPLC-MS/MS method should enhance further research into bupropion stereoselective metabolism and drug interactions. Copyright © 2016 Elsevier B.V. All rights reserved.

Solid phase extraction with high polarity Carb/PSA as composite fillers prior to UPLC-MS/MS to determine six bisphenols and alkylphenols in trace level hotpot seasoning.

PubMed

Dong, Hao; Zeng, Xiaofang; Bai, Weidong

2018-08-30

The present study reports an ultra high-performance liquid chromatography tandem mass spectrometry method for the simultaneous determination of six bisphenols (bisphenol A, bisphenol B and bisphenol F) and alkylphenols (4-nonylphenol, 4-n-nonylphenol and octylphenol) in hotpot seasoning. Samples were dispersed in n-hexane after addition of internal standards bisphenol A-d 4 and 4-n-nonylphenol-d 4 . Sample solutions were then centrifuged, and the supernatants purified using solid phase extraction with high polarity Carb/PSA composite fillers. Six target analytes were separated on a Waters ACQUITY BEH C18 column by gradient elution with methanol and 0.05% ammonium hydroxide in water as the mobile phase, and determined under multiple reactions monitoring mode. The limits of detection and quantitation, matrix effect, recovery and precision of the method were investigated. Results were linear in the concentration range 0.1-250 µg/L for all compounds of interest, with R 2  > 0.9950. Limits of detection were in the range 0.1-0.4 μg/kg, and limits of quantitation were between 0.5 μg/kg and 1.0 μg/kg. The mean recoveries for negative samples at three spiked concentrations were in the range 87.9%-102.4%, and the intra-day precision and inter-day precision were in the ranges 2.1-8.2% and 4.8-11.2%, respectively. This method is accurate and sensitive, and had good clean-up characteristics, which might apply to screening and quantitation of target bisphenols and alkylphenols in hotpot seasoning. Copyright © 2018 Elsevier Ltd. All rights reserved.

The construct validity of session RPE during an intensive camp in young male Karate athletes.

PubMed

Padulo, Johnny; Chaabène, Helmi; Tabben, Montassar; Haddad, Monoem; Gevat, Cecilia; Vando, Stefano; Maurino, Lucio; Chaouachi, Anis; Chamari, Karim

2014-04-01

the aim of this study was to assess the validity of the session rating of perceived exertion (RPE) method and two objective HR-based methods for quantifying karate's training load (TL) in young Karatekas. eleven athletes (age 12.50±1.84 years) participated in this study. The training period/camp was performed on 5 consecutive days with two training session (s) per-day (d). Construct validity of RPE method in young Karate athletes, was studied by correlation analysis between RPE session's training load and both Edwards and Banister's training impulse score' method. significant relationship was found between inter-day (n-11 × d-5 × s-2 = 110) sessions RPE and Edwards (r values from 0.84 to 0.92 p < 0.001) and Banister's (r values from 0.84 to 0.97 p < 0.001), respectively. this study showed that session-RPE can be considered a valid method for quantifying karate's training load in young karate athletes.

Use of ceric ammonium sulphate and two dyes, methyl orange and indigo carmine, in the determination of lansoprazole in pharmaceuticals.

PubMed

Basavaiah, Kanakapura; Ramakrishna, Veeraiah; Kumar, Urdigere Rangachar Anil

2007-06-01

Two spectrophotometric methods are proposed for the assay of lansoprazole (LPZ) in bulk drug and in dosage forms using ceric ammonium sulphate (CAS) and two dyes, methyl orange and indigo carmine, as reagents. The methods involve addition of a known excess of CAS to LPZ in acid medium, followed by determination of residual CAS by reacting with a fixed amount of either methyl orange, measuring the absorbance at 520 nm (method A), or indigo carmine, measuring the absorbance at 610 nm (method B). In both methods, the amount of CAS reacted corresponds to the amount of LPZ and the measured absorbance was found to increase linearly with the concentration of LPZ, which is corroborated by the correlation coefficients of 0.9979 and 0.9954 for methods A and B, respectively. The systems obey Beer's law for 0.5-7.0 microg mL(-1) and 0.25-3.0 microg mL(-1) for methods A and B, respectively. The apparent molar absorptivities were calculated to be 3.0 x 10(4) and 4.4 x 10(4) L mol(-1) cm(-1) for methods A and B, respectively. The limits of detection (LOD) and quantification (LOQ) were calculated to be 0.08 and 0.25 microg mL(-1) for method A, and 0.09 and 0.27 microg mLs(-1) for method B, respectively. The intra-day and inter-day precision and accuracy of the methods were evaluated according to the current ICH guidelines. Both methods were of comparable accuracy (er < or = 2 %). Also, both methods are equally precise as shown by the relative standard deviation values < 1.5%. No interference was observed from common pharmaceutical adjuvants. The accuracy of the methods was further ascertained by performing recovery studies using the standard addition method. The methods were successfully applied to the assay of LPZ in capsule preparations and the results were statistically compared with those of the literature UV-spectrophotometric method by applying Student's t-test and F-test.

Quantitation of fumonisin B1 and B2 in feed using FMOC pre-column derivatization with HPLC and fluorescence detection.

PubMed

Smith, Lori L; Francis, Kyle A; Johnson, Joseph T; Gaskill, Cynthia L

2017-11-01

Pre-column derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) was determined to be effective for quantitation of fumonisins B 1 and B 2 in feed. Liquid-solid extraction, clean-up using immunoaffinity solid phase extraction chromatography, and FMOC-derivatization preceded analysis by reverse phase HPLC with fluorescence. Instrument response was unchanged in the presence of matrix, indicating no need to use matrix-matched calibrants. Furthermore, high method recoveries indicated calibrants do not need to undergo clean-up to account for analyte loss. Established method features include linear instrument response from 0.04-2.5µg/mL and stable derivatized calibrants over 7days. Fortified cornmeal method recoveries from 0.1-30.0μg/g were determined for FB 1 (75.1%-109%) and FB 2 (96.0%-115.2%). Inter-assay precision ranged from 1.0%-16.7%. Method accuracy was further confirmed using certified reference material. Inter-laboratory comparison with naturally-contaminated field corn demonstrated equivalent results with conventional derivatization. These results indicate FMOC derivatization is a suitable alternative for fumonisins B 1 and B 2 quantitation in corn-based feeds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inter-observer agreement of a multi-parameter campsite monitoring program on the Dixie National Forest, Utah

Treesearch

Nicholas J. Glidden; Martha E. Lee

2007-01-01

Precision is crucial to campsite monitoring programs. Yet, little empirical research has ever been published on the level of precision of this type of monitoring programs. The purpose of this study was to evaluate the level of agreement between observers of campsite impacts using a multi-parameter campsite monitoring program. Thirteen trained observers assessed 16...

Validation of high-throughput single cell analysis methodology.

PubMed

Devonshire, Alison S; Baradez, Marc-Olivier; Morley, Gary; Marshall, Damian; Foy, Carole A

2014-05-01

High-throughput quantitative polymerase chain reaction (qPCR) approaches enable profiling of multiple genes in single cells, bringing new insights to complex biological processes and offering opportunities for single cell-based monitoring of cancer cells and stem cell-based therapies. However, workflows with well-defined sources of variation are required for clinical diagnostics and testing of tissue-engineered products. In a study of neural stem cell lines, we investigated the performance of lysis, reverse transcription (RT), preamplification (PA), and nanofluidic qPCR steps at the single cell level in terms of efficiency, precision, and limit of detection. We compared protocols using a separate lysis buffer with cell capture directly in RT-PA reagent. The two methods were found to have similar lysis efficiencies, whereas the direct RT-PA approach showed improved precision. Digital PCR was used to relate preamplified template copy numbers to Cq values and reveal where low-quality signals may affect the analysis. We investigated the impact of calibration and data normalization strategies as a means of minimizing the impact of inter-experimental variation on gene expression values and found that both approaches can improve data comparability. This study provides validation and guidance for the application of high-throughput qPCR workflows for gene expression profiling of single cells. Copyright © 2014 Elsevier Inc. All rights reserved.

Development and validation of a rapid and sensitive UPLC-MS/MS method for determination of uracil and dihydrouracil in human plasma.

PubMed

Jacobs, Bart A W; Rosing, Hilde; de Vries, Niels; Meulendijks, Didier; Henricks, Linda M; Schellens, Jan H M; Beijnen, Jos H

2016-07-15

Quantification of the endogenous dihydropyrimidine dehydrogenase (DPD) substrate uracil (U) and the reaction product dihydrouracil (UH2) in plasma might be suitable for identification of patients at risk of fluoropyrimidine-induced toxicity as a result of DPD deficiency. In this paper, we describe the development and validation of a rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay for quantification of U and UH2 in human plasma. Analytes were extracted by protein precipitation, chromatographically separated on an Acquity UPLC(®) HSS T3 column with gradient elution and analyzed with a tandem mass spectrometer equipped with an electrospray ionization source. U was quantified in the negative ion mode and UH2 in the positive ion mode. Stable isotopes for U and UH2 were used as internal standards. Total chromatographic run time was 5min. Validated concentration ranges for U and UH2 were from 1 to 100ng/mL and 10 to 1000ng/mL, respectively. Inter-assay bias and inter-assay precision for U were within ±2.8% and ≤12.4%. For UH2, inter-assay bias and inter-assay precision were within ±2.9% and ≤7.2%. Adequate stability of U and UH2 in dry extract, final extract, stock solution and plasma was demonstrated. Stability of U and UH2 in whole blood was only satisfactory when stored up to 4hours at 2-8°C, but not at ambient temperatures. An accurate, precise and sensitive UPLC-MS/MS assay for quantification of U and UH2 in plasma was developed. This assay is now applied to support clinical studies with fluoropyrimidine drugs. Copyright © 2016 Elsevier B.V. All rights reserved.

Absolute Isotopic Abundance Ratios and the Accuracy of Δ47 Measurements

NASA Astrophysics Data System (ADS)

Daeron, M.; Blamart, D.; Peral, M.; Affek, H. P.

2016-12-01

Conversion from raw IRMS data to clumped isotope anomalies in CO2 (Δ47) relies on four external parameters: the (13C/12C) ratio of VPDB, the (17O/16O) and (18O/16O) ratios of VSMOW (or VPDB-CO2), and the slope of the triple oxygen isotope line (λ). Here we investigate the influence that these isotopic parameters exert on measured Δ47 values, using real-world data corresponding to 7 months of measurements; simulations based on randomly generated data; precise comparisons between water-equilibrated CO2 samples and between carbonate standards believed to share quasi-identical Δ47 values; reprocessing of two carbonate calibration data sets with different slopes of Δ47 versus T. Using different sets of isotopic parameters generally produces systematic offsets as large as 0.04 ‰ in final Δ47 values. What's more, even using a single set of isotopic parameters can produce intra- and inter-laboratory discrepancies in final Δ47 values, if some of these parameters are inaccurate. Depending on the isotopic compositions of the standards used for conversion to "absolute" values, these errors should correlate strongly with either δ13C or δ18O, or more weakly with both. Based on measurements of samples expected to display identical Δ47 values, such as 25°C water-equilibrated CO2 with different carbon and oxygen isotope compositions, or high-temperature standards ETH-1 and ETH-2, we conclude that the isotopic parameters used so far in most clumped isotope studies produces large, systematic errors controlled by the relative bulk isotopic compositions of samples and standards, which should be one of the key factors responsible for current inter-laboratory discrepancies. By contrast, the isotopic parameters of Brand et al. [2010] appear to yield accurate Δ47 values regardless of bulk isotopic composition. References:Brand, Assonov and Coplen [2010] http://dx.doi.org/10.1351/PAC-REP-09-01-05

[Inter-Occupational Cooperation Levels in a Day Care Service and Its Subjects - From the Viewpoint of Multiple Occupations].

PubMed

Ugai, Chizuru; Hata, Kiyomi

2016-12-01

We clarified the role of cooperation of nursing personnel who work in day care services, to precede our examination of inter-occupational cooperation. The study results revealed that there were four cooperation levels. Subjects for the cooperation included:"difficulty in sharing information,"difficulty in understanding the whole picture,"difficulty in finding directions, "and"difficulty in dealing with emergency cases."The purpose of this study was to clarify the inter-occupational cooperation levels in a day care service and its subjects. We also conducted semi-structured interviews with 13 persons of differing occupations(other than nurses), and who worked in day-care services in A prefecture. As a result, it was revealed that there were three inter-occupational cooperation levels and its subjects included:"difficulty in sharing information" (which was answered the same as the nurses),"difficulty in sharing goals"(which were different among individual occupations), "lack of consistency in care,"necessity of learning because of insufficient knowledge,"and"hesitation to notify."

Projected Changes in Temperature and Precipitation Extremes over China as Measured by 50-yr Return Values and Periods Based on a CMIP5 Ensemble

NASA Astrophysics Data System (ADS)

Xu, Ying; Gao, Xuejie; Giorgi, Filippo; Zhou, Botao; Shi, Ying; Wu, Jie; Zhang, Yongxiang

2018-04-01

Future changes in the 50-yr return level for temperature and precipitation extremes over mainland China are investigated based on a CMIP5 multi-model ensemble for RCP2.6, RCP4.5 and RCP8.5 scenarios. The following indices are analyzed: TXx and TNn (the annual maximum and minimum of daily maximum and minimum surface temperature), RX5day (the annual maximum consecutive 5-day precipitation) and CDD (maximum annual number of consecutive dry days). After first validating the model performance, future changes in the 50-yr return values and return periods for these indices are investigated along with the inter-model spread. Multi-model median changes show an increase in the 50-yr return values of TXx and a decrease for TNn, more specifically, by the end of the 21st century under RCP8.5, the present day 50-yr return period of warm events is reduced to 1.2 yr, while extreme cold events over the country are projected to essentially disappear. A general increase in RX5day 50-yr return values is found in the future. By the end of the 21st century under RCP8.5, events of the present RX5day 50-yr return period are projected to reduce to < 10 yr over most of China. Changes in CDD-50 show a dipole pattern over China, with a decrease in the values and longer return periods in the north, and vice versa in the south. Our study also highlights the need for further improvements in the representation of extreme events in climate models to assess the future risks and engineering design related to large-scale infrastructure in China.

Characterising the Land Surface Phenology of Mediterranean Pinus species using the MODIS NDVI time series

NASA Astrophysics Data System (ADS)

Rodriguez-Galiano, Victor; Aragones, David; Navarro-Cerrillo, Rafael M.; Caparros-Santiago, Jose A.

2017-04-01

Land surface phenology (LSP) can improve the monitoring of forest areas and their change processes. The aim of this work is to characterize the temporal dynamics in Mediterranean Pinus forests. The different experiments were based on 679 mono-specific plots for the 5 native species in the Iberian Peninsula: P. sylvestris, P. pinea, P. halepensis, P. nigra and P. pinaster, which were obtained from the Third National Forest Inventory of Spain. The whole MODIS NDVI time series (2000-2016) were used to characterize the seasonal behavior of the pine forest. The following phenological parameters were extracted for each cycle from the smoothed time series: the day of beginning, end, middle and the length in days of season also base value, maximum value, amplitude and integrated value. Multi-temporal metrics were calculated to synthesize the inter-annual variability of the phenological parameters. An atypical behavior was detected for the years 2004 and 2011 and 2000, 2009 and 2015 for all Pinus species, matching wet and dry cycles, respectively. The inter and intra-species analysis of NDVI and LSP showed two different patterns: an important decreasing during the summer for those species such as P. halepensis, P. pinea y P. pinaster; and a lower NDVI variation among the year for P. sylvestris and P. nigra in certain areas. P. sylvestris had a phenological behavior different to P. pinea, P. halepensis and P. pinaster. P. nigra showed and heterogeneous intra-specific behaviour that might be associated to the existence of subspecies with different phenology.

Stability of compounded trilostane suspension in cod liver oil.

PubMed

Crosby, Jesse; Brown, Stacy

2017-10-01

Trilostane is a synthetic steroid analog used to treat canine hyperadrenocorticism. For small dogs, the dose found in commercially available dosage forms of trilostane is sometimes too high. Compounding trilostane in a liquid diluent provides an option for more precise dosing and adjustments, and can be easier to administer, versus a tablet or capsule. Trilostane suspends well in cod liver oil, which is generally palatable to dogs. The stability of a compounded trilostane suspension in cod liver oil stored at room temperature was investigated for 90 days. Compounded trilostane retained stability, defined as maintaining 90-105% labeled value, for 60 days when stored in amber glass bottles. However, drug potency fell >10% below the labeled value when stored in amber plastic bottles after 7 days. Copyright © 2017 Elsevier Ltd. All rights reserved.

Airborne Evaluation and Demonstration of a Time-Based Airborne Inter-Arrival Spacing Tool

NASA Technical Reports Server (NTRS)

Lohr, Gary W.; Oseguera-Lohr, Rosa M.; Abbott, Terence S.; Capron, William R.; Howell, Charles T.

2005-01-01

An airborne tool has been developed that allows an aircraft to obtain a precise inter-arrival time-based spacing interval from the preceding aircraft. The Advanced Terminal Area Approach Spacing (ATAAS) tool uses Automatic Dependent Surveillance-Broadcast (ADS-B) data to compute speed commands for the ATAAS-equipped aircraft to obtain this inter-arrival spacing behind another aircraft. The tool was evaluated in an operational environment at the Chicago O'Hare International Airport and in the surrounding terminal area with three participating aircraft flying fixed route area navigation (RNAV) paths and vector scenarios. Both manual and autothrottle speed management were included in the scenarios to demonstrate the ability to use ATAAS with either method of speed management. The results on the overall delivery precision of the tool, based on a target spacing of 90 seconds, were a mean of 90.8 seconds with a standard deviation of 7.7 seconds. The results for the RNAV and vector cases were, respectively, M=89.3, SD=4.9 and M=91.7, SD=9.0.

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.

Polymeric ionic liquid coatings versus commercial solid-phase microextraction coatings for the determination of volatile compounds in cheeses.

PubMed

Trujillo-Rodríguez, María J; Yu, Honglian; Cole, William T S; Ho, Tien D; Pino, Verónica; Anderson, Jared L; Afonso, Ana M

2014-04-01

The extraction performance of four polymeric ionic liquid (PIL)-based solid-phase microextraction (SPME) coatings has been studied and compared to that of commercial SPME coatings for the extraction of 16 volatile compounds in cheeses. The analytes include 2 free fatty acids, 2 aldehydes, 2 ketones and 10 phenols and were determined by headspace (HS)-SPME coupled to gas chromatography (GC) with flame-ionization detection (FID). The PIL-based coatings produced by UV co-polymerization were more efficient than PIL-based coatings produced by thermal AIBN polymerization. Partition coefficients of analytes between the sample and the coating (Kfs) were estimated for all PIL-based coatings and the commercial SPME fiber showing the best performance among the commercial fibers tested: carboxen-polydimethylsyloxane (CAR-PDMS). For the PIL-based fibers, the highest K(fs) value (1.96 ± 0.03) was obtained for eugenol. The normalized calibration slope, which takes into account the SPME coating thickness, was also used as a simpler approximate tool to compare the nature of the coating within the determinations, with results entirely comparable to those obtained with estimated K(fs) values. The PIL-based materials obtained by UV co-polymerization containing the 1-vinyl-3-hexylimidazolium chloride IL monomer and 1,12-di(3-vinylimiazolium)dodecane dibromide IL crosslinker exhibited the best performance in the extraction of the select analytes from cheeses. Despite a coating thickness of only 7 µm, this copolymeric sorbent coating was capable of quantitating analytes in HS-SPME in a 30 to 2000 µg L(-1) concentration range, with correlation coefficient (R) values higher than 0.9938, inter-day precision values (as relative standard deviation in %) varying from 6.1 to 20%, and detection limits down to 1.6 µg L(-1). Copyright © 2013 Elsevier B.V. All rights reserved.

New Frontiers in Characterization of Sub-Catalog Microseismicity: Utilizing Inter-Event Waveform Cross Correlation for Estimating Precise Locations, Magnitudes, and Focal Mechanisms of Tiny Earthquakes

NASA Astrophysics Data System (ADS)

Ellsworth, W. L.; Shelly, D. R.; Hardebeck, J.; Hill, D. P.

2017-12-01

Microseismicity often conveys the most direct information about active processes in the earth's subsurface. However, routine network processing typically leaves most earthquakes uncharacterized. These "sub-catalog" events can provide critical clues to ongoing processes in the source region. To address this issue, we have developed waveform-based processing that leverages the existing routine catalog of earthquakes to detect and characterize "sub-catalog" events (those absent in routine catalogs). By correlating waveforms of cataloged events with the continuous data stream, we 1) identify events with similar waveform signatures in the continuous data across multiple stations, 2) precisely measure relative time lags across these stations for both P- and S-wave time windows, and 3) estimate the relative polarity between events by the sign of the peak absolute value correlations and its height above the secondary peak. When combined, these inter-event comparisons yield robust measurements, which enable sensitive event detection, relative relocation, and relative magnitude estimation. The most recent addition, focal mechanisms derived from correlation-based relative polarities, addresses a significant shortcoming in microseismicity analyses (see Shelly et al., JGR, 2016). Depending on the application, we can characterize 2-10 times as many events as included in the initial catalog. This technique is particularly well suited for compact zones of active seismicity such as seismic swarms. Application to a 2014 swarm in Long Valley Caldera, California, illuminates complex patterns of faulting that would have otherwise remained obscured. The prevalence of such features in other environments remains an important, as yet unresolved, question.

Community-based Approaches to Improving Accuracy, Precision, and Reproducibility in U-Pb and U-Th Geochronology

NASA Astrophysics Data System (ADS)

McLean, N. M.; Condon, D. J.; Bowring, S. A.; Schoene, B.; Dutton, A.; Rubin, K. H.

2015-12-01

The last two decades have seen a grassroots effort by the international geochronology community to "calibrate Earth history through teamwork and cooperation," both as part of the EARTHTIME initiative and though several daughter projects with similar goals. Its mission originally challenged laboratories "to produce temporal constraints with uncertainties approaching 0.1% of the radioisotopic ages," but EARTHTIME has since exceeded its charge in many ways. Both the U-Pb and Ar-Ar chronometers first considered for high-precision timescale calibration now regularly produce dates at the sub-per mil level thanks to instrumentation, laboratory, and software advances. At the same time new isotope systems, including U-Th dating of carbonates, have developed comparable precision. But the larger, inter-related scientific challenges envisioned at EARTHTIME's inception remain - for instance, precisely calibrating the global geologic timescale, estimating rates of change around major climatic perturbations, and understanding evolutionary rates through time - and increasingly require that data from multiple geochronometers be combined. To solve these problems, the next two decades of uranium-daughter geochronology will require further advances in accuracy, precision, and reproducibility. The U-Th system has much in common with U-Pb, in that both parent and daughter isotopes are solids that can easily be weighed and dissolved in acid, and have well-characterized reference materials certified for isotopic composition and/or purity. For U-Pb, improving lab-to-lab reproducibility has entailed dissolving precisely weighed U and Pb metals of known purity and isotopic composition together to make gravimetric solutions, then using these to calibrate widely distributed tracers composed of artificial U and Pb isotopes. To mimic laboratory measurements, naturally occurring U and Pb isotopes were also mixed in proportions to mimic samples of three different ages, to be run as internal standards and as measures of inter-laboratory reproducibility. The U-Th community is undertaking many of the same protocols, and has recently created publicly available gravimetric solutions, and large volumes of three age solutions for widespread distribution and inter-laboratory comparison.

Fusing Continuous-Valued Medical Labels Using a Bayesian Model.

PubMed

Zhu, Tingting; Dunkley, Nic; Behar, Joachim; Clifton, David A; Clifford, Gari D

2015-12-01

With the rapid increase in volume of time series medical data available through wearable devices, there is a need to employ automated algorithms to label data. Examples of labels include interventions, changes in activity (e.g. sleep) and changes in physiology (e.g. arrhythmias). However, automated algorithms tend to be unreliable resulting in lower quality care. Expert annotations are scarce, expensive, and prone to significant inter- and intra-observer variance. To address these problems, a Bayesian Continuous-valued Label Aggregator (BCLA) is proposed to provide a reliable estimation of label aggregation while accurately infer the precision and bias of each algorithm. The BCLA was applied to QT interval (pro-arrhythmic indicator) estimation from the electrocardiogram using labels from the 2006 PhysioNet/Computing in Cardiology Challenge database. It was compared to the mean, median, and a previously proposed Expectation Maximization (EM) label aggregation approaches. While accurately predicting each labelling algorithm's bias and precision, the root-mean-square error of the BCLA was 11.78 ± 0.63 ms, significantly outperforming the best Challenge entry (15.37 ± 2.13 ms) as well as the EM, mean, and median voting strategies (14.76 ± 0.52, 17.61 ± 0.55, and 14.43 ± 0.57 ms respectively with p < 0.0001). The BCLA could therefore provide accurate estimation for medical continuous-valued label tasks in an unsupervised manner even when the ground truth is not available.

Inferred fish behavior its implications for hydroacoustic surveys in nearshore habitats

USGS Publications Warehouse

DuFour, Mark R.; Mayer, Christine M.; Qian, Song S.; Vandergoot, Christopher; Kraus, Richard T.; Kocovsky, Patrick; Warner, David M.

2018-01-01

Population availability and vessel avoidance effects on hydroacoustic abundance estimates may be scale dependent; therefore, it is important to evaluate these biases across systems. We performed an inter-ship comparison survey to determine the effect of vessel size, day-night period, depth, and environmental gradients on walleye (Sander vitreus) density estimates in Lake Erie, an intermediate-scaled system. Consistent near-bottom depth distributions coupled with horizontal fish movements relative to vessel paths indicated avoidance behavior contributed to higher walleye densities from smaller vessels in shallow water (i.e., <15 m), although the difference decreased with increasing depth. Diel bank migrations in response to seasonally varying onshore-to-offshore environmental gradients likely contributed to day-night differences in densities between sampling locations and seasons. Spatial and unexplained variation accounted for a high proportion of total variation; however, increasing sampling intensity can mitigate effects on precision. Therefore, researchers should minimize systematic avoidance and availability related biases (i.e., vessel and day-night period) to improve population abundance estimates. Quantifying availability and avoidance behavior effects and partitioning sources of variation provides informed flexibility for designing future hydroacoustic surveys in shallow-water nearshore environments.

Customization of UWB 3D-RTLS Based on the New Uncertainty Model of the AoA Ranging Technique

PubMed Central

Jachimczyk, Bartosz; Dziak, Damian; Kulesza, Wlodek J.

2017-01-01

The increased potential and effectiveness of Real-time Locating Systems (RTLSs) substantially influence their application spectrum. They are widely used, inter alia, in the industrial sector, healthcare, home care, and in logistic and security applications. The research aims to develop an analytical method to customize UWB-based RTLS, in order to improve their localization performance in terms of accuracy and precision. The analytical uncertainty model of Angle of Arrival (AoA) localization in a 3D indoor space, which is the foundation of the customization concept, is established in a working environment. Additionally, a suitable angular-based 3D localization algorithm is introduced. The paper investigates the following issues: the influence of the proposed correction vector on the localization accuracy; the impact of the system’s configuration and LS’s relative deployment on the localization precision distribution map. The advantages of the method are verified by comparing them with a reference commercial RTLS localization engine. The results of simulations and physical experiments prove the value of the proposed customization method. The research confirms that the analytical uncertainty model is the valid representation of RTLS’ localization uncertainty in terms of accuracy and precision and can be useful for its performance improvement. The research shows, that the Angle of Arrival localization in a 3D indoor space applying the simple angular-based localization algorithm and correction vector improves of localization accuracy and precision in a way that the system challenges the reference hardware advanced localization engine. Moreover, the research guides the deployment of location sensors to enhance the localization precision. PMID:28125056

Customization of UWB 3D-RTLS Based on the New Uncertainty Model of the AoA Ranging Technique.

PubMed

Jachimczyk, Bartosz; Dziak, Damian; Kulesza, Wlodek J

2017-01-25

The increased potential and effectiveness of Real-time Locating Systems (RTLSs) substantially influence their application spectrum. They are widely used, inter alia, in the industrial sector, healthcare, home care, and in logistic and security applications. The research aims to develop an analytical method to customize UWB-based RTLS, in order to improve their localization performance in terms of accuracy and precision. The analytical uncertainty model of Angle of Arrival (AoA) localization in a 3D indoor space, which is the foundation of the customization concept, is established in a working environment. Additionally, a suitable angular-based 3D localization algorithm is introduced. The paper investigates the following issues: the influence of the proposed correction vector on the localization accuracy; the impact of the system's configuration and LS's relative deployment on the localization precision distribution map. The advantages of the method are verified by comparing them with a reference commercial RTLS localization engine. The results of simulations and physical experiments prove the value of the proposed customization method. The research confirms that the analytical uncertainty model is the valid representation of RTLS' localization uncertainty in terms of accuracy and precision and can be useful for its performance improvement. The research shows, that the Angle of Arrival localization in a 3D indoor space applying the simple angular-based localization algorithm and correction vector improves of localization accuracy and precision in a way that the system challenges the reference hardware advanced localization engine. Moreover, the research guides the deployment of location sensors to enhance the localization precision.

Monitoring ovarian cycles, pregnancy and post-partum in captive marsh deer (Blastocerus dichotomus) by measuring fecal steroids

PubMed Central

Polegato, Bruna Furlan; Duarte, José Maurício Barbanti

2018-01-01

Abstract The marsh deer is an endangered species from the marshlands of central South America. This study aimed to characterize certain aspects of the reproductive physiology of marsh deer hinds, including the duration and fecal progestins profile of the estrous cycle, pregnancy and post-partum periods, and evaluate the effect of cloprostenol administration on this species. The experimental group consisted of six females and one fertile male marsh deer. During monitoring of the estrous cycle, the fresh fecal samples were collected daily and, during pregnancy, they were collected twice weekly. The hormonal profile obtained from daily fecal samples indicated that the mean duration of the estrous cycle was 21.3 ± 1.3 days (6.4 days inter-luteal phase and 14.8 days luteal phase; n = 16 estrous cycles). The mean concentration of fecal progestins in the inter-luteal phase was 834 ± 311 ng g−1, in the luteal phase was 3979 ± 1611 ng g−1, value between them was 1457 ng g−1. No significant difference in fecal estrogen concentrations was determined during the estrous cycle. The corpora luteum was not responsive to cloprostenol until Day 6 of the estrous cycle, the period previously described as the inter-luteal phase. Half the females became pregnant following treatment with cloprostenol and two others were fertilized in their natural estrous cycle. Four females delivered fawns, and the mean duration of pregnancy was 253 ± 4 days. Fecal progestin concentrations were similar to those of the estrous cycle during the first 11 weeks of pregnancy and increased significantly ( > 15250 ng g−1) thereafter, providing a presumptive diagnosis guideline. Within 60 days of post-partum analyses, 75% of the deer exhibited behavioural estrus and/or ovarian activity. This study generated a broader understanding of the marsh deer species concerning the production of consistent data related to its reproduction. This knowledge can be used to assist the reproductive management of this species and, consequently, to promote its conservation. PMID:29383254

Performance score variation between days at Australian national and Olympic women's artistic gymnastics competition.

PubMed

Bradshaw, Elizabeth Jane; Hume, Patria Anne; Aisbett, Brad

2012-01-01

We determined the inter-day variability in elite-standard women's artistic gymnastics competition scores. National (50 gymnasts for up to three days) and Olympic (24 gymnasts for up to five days) competition scores published in the public domain ('Giant poster pull-out', 2010 ; Gymnastics Australia, 2008 ) were evaluated using three statistical measures. Analyses of the inter-day differences in the mean scores as a percentage (MDiff%), coefficient of variation percentages for the mean score across both days (CV%), and Pearson correlation coefficients for the inter-day score (r) were interpreted using thresholds from trivial to large. National-class gymnasts' two-day performance variation was trivial for vault, small for floor and beam, and moderate for bars. When senior gymnasts competed for a third day the performance variation increased to moderate for vault. Across five days of Olympic competition there were trivial (e.g. CV%: vault = 0.8) to small (e.g. CV%: bars = 2.0) variations in performances between days on all apparatus. Olympians' performance score consistency is superior to senior, national-class competitors. The performance score consistency required for gymnasts who aspire to participate at the Olympics as a top-24 competitor is better than 3%.

Contested Technologies and Design for Values: The Case of Shale Gas.

PubMed

Dignum, Marloes; Correljé, Aad; Cuppen, Eefje; Pesch, Udo; Taebi, Behnam

2016-08-01

The introduction of new energy technologies may lead to public resistance and contestation. It is often argued that this phenomenon is caused by an inadequate inclusion of relevant public values in the design of technology. In this paper we examine the applicability of the value sensitive design (VSD) approach. While VSD was primarily introduced for incorporating values in technological design, our focus in this paper is expanded towards the design of the institutions surrounding these technologies, as well as the design of stakeholder participation. One important methodological challenge of VSD is to identify the relevant values related to new technological developments. In this paper, we argue that the public debate can form a rich source from which to retrieve the values at stake. To demonstrate this, we have examined the arguments used in the public debate regarding the exploration and exploitation of shale gas in the Netherlands. We identified two important sets of the underlying values, namely substantive and procedural values. This paper concludes with two key findings. Firstly, contrary to what is often suggested in the literature, both proponents and opponents seem to endorse the same values. Secondly, contestation seems to arise in the precise operationalization of these values among the different stakeholders. In other words, contestation in the Dutch shale gas debate does not arise from inter-value conflict but rather from intra-value conflicts. This multi-interpretability should be incorporated in VSD processes.

Development and validation of an analytical method using UPLC-MS/MS to quantify everolimus in dried blood spots in the oncology setting.

PubMed

Knapen, Lotte M; Beer, Yvo de; Brüggemann, Roger J M; Stolk, Leo M; Vries, Frank de; Tjan-Heijnen, Vivianne C G; Erp, Nielka P van; Croes, Sander

2018-02-05

While the therapeutic drug monitoring (TDM) of everolimus has been routinely performed for over 10 years in solid organ transplantation medicine, in order to optimize the balance between effectiveness and toxicity, it is yet uncommon in the treatment of malignancies. The aim of this study was to develop and validate a bioanalytical method to quantify everolimus in dried blood spots (DBS) to facilitate TDM for the oncology outpatient setting. The hematocrit effect of everolimus was investigated. An 7.5mm disk from the central part of the DBS was punched, followed by the extraction of everolimus from the DBS by methanol/acetonitrile (80/20%) spiked with deuterium-labelled everolimus as internal standard. Subsequently, everolimus was separated and analyzed using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The UPLC-MS/MS method was validated according to the European Medicine Agency (EMA) guideline. Everolimus concentrations could be quantified over the range of 3-75μg/L. The intra- and inter-assay precision and accuracy of the method were shown to be acceptable (coefficient of variation ≤10.7% and relative error ≤4.4%, respectively). The matrix effects appeared to be influenced by the hematocrit effect. The hematocrit effect was tested in a range of 0.20-0.50L/L, at which hematocrit accuracy and precision were satisfactory at values ≥0.25L/L. However, at 0.20L/L hematocrit in combination with high everolimus concentrations of 20 and 40μg/L, the precision was adequate (≤7.4%), but the accuracy was >15% of the nominal concentration. Everolimus was stable in DBS for at least 80days at 2-8°C. Given these results, the everolimus DBS method has been successfully developed and validated. Special attention is necessary for cancer patients with both a 0.20L/L hematocrit in combination with everolimus concentrations ≥20μg/L. A clinical validation for the use of everolimus DBS in cancer patients is currently being undertaken. Copyright © 2017 Elsevier B.V. All rights reserved.

Buprenorphine and nor-buprenorphine levels in head hair samples from former heroin users under Suboxone® treatment.

PubMed

Belivanis, Stamatis; Tzatzarakis, Manolis N; Vakonaki, Elena; Kovatsi, Leda; Mantsi, Mary; Alegakis, Athanasios; Kavvalakis, Matthaios P; Vynias, Dionisios; Tsatsakis, Aristidis M

2014-06-01

In the current study, buprenorphine (BUP) and its major metabolite, nor-buprenorphine (NBUP), were determined in hair samples from former heroin users following Suboxone® treatment. Hair samples from 36 subjects were analyzed. The drugs of interest were isolated from hair by solid-liquid extraction with methanol and were determined by liquid chromatography-mass spectrometry, using an electrospray ionization interface. The analytical parameters of the method (such as linearity, limits of quantification, recovery, accuracy, and precision) were determined. The inter-quartile range of BUP levels was from 11.4 to 37.4 pg/mg (mean value 56.6 pg/mg) for the proximal hair segment, from 5.8 to 43.3 pg/mg for the middle hair segment (mean value 25.3 pg/mg), while a range from 4.3 to 33.9 pg/mg (mean value 105.2 pg/mg) for the distant to the root hair segment was determined. For NBUP the corresponding inter-quartile range was from 27.0 to 147.6 for the proximal segment (mean value 95.4 pg/mg), from 21.5 to 164.7 pg/mg for the middle segment (mean value 102.0 pg/mg) and from 20.4 to 103.6 pg/mg for the distant segment (mean value 156.8 pg/mg). The mean BUP/NBUP concentration ratio was 0.5. The daily dose of Suboxone® correlated significantly with BUP and NBUP levels in hair (p = 0.001 and p = 0.023) as well as with the BUP/NBUP ratio (p = 0.010). No significant correlation was found between the levels of BUP and NBUP and the duration of Suboxone® administration. The developed and validated method was successfully used for the determination of BUP and NBUP in hair samples collected from former heroin users under Suboxone® treatment. Copyright © 2014 John Wiley & Sons, Ltd.

Magnetic testing for inter-granular crack defect of tubing coupling

NASA Astrophysics Data System (ADS)

Hu, Bo; Yu, Runqiao

2018-04-01

This study focused on the inter-granular crack defects of tubing coupling wherein a non-destructive magnetic testing technique was proposed to determine the magnetic flux leakage features on coupling surface in the geomagnetic field using a high-precision magnetic sensor. The abnormal magnetic signatures of defects were analysed, and the principle of the magnetic test was explained based on the differences in the relative permeability of defects and coupling materials. Abnormal fluctuations of the magnetic signal were observed at the locations of the inter-granular crack defects. Imaging showed the approximate position of defects. The test results were proven by metallographic phase.

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

PubMed

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

2005-11-05

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

Stability-indicating RP-HPLC Method for the Simultaneous Determination of Sitagliptin and Simvastatin in Tablets

PubMed Central

Ramalingam, P.; Bhaskar, V. Udaya; Reddy, Y. Padmanabha; Kumar, K. Vinod

2014-01-01

A new stability-indicating high-performance liquid chromatographic method for simultaneous analysis of sitagliptin and simvastatin in pharmaceutical dosage form was developed and validated. The mobile phase consisted of methanol and water (70:30, v/v) with 0.2 % of n-heptane sulfonic acid adjusted to pH 3.0 with ortho phosphoric acid was used. Retentions of sitagliptin and simvastatin were 4.3 min and 30.4 min, respectively with a flow rate of 1 ml/min on C8 (Qualisil BDS, 250×4.6 mm, 5 μ). Eluents were detected at 253 nm using photodiode diode array detector. The linear regression analysis data for the linearity plot showed correlation coefficient values of 0.9998 and 0.9993 for sitagliptin and simvastatin, with respective concentration ranges of 20-150 μg/ml and 8-60 μg/ml. The relative standard deviation for inter-day precision was lower than 2.0%. The assay of sitagliptin and simvastatin was determined in tablet dosage form was found to be within limits. Both drugs were subjected to a variety of stress conditions such as acidic, basic, oxidation, photolytic, neutral and thermal stress in order to achieve adequate degradation. Results revealed that considerable degradation was found in all stress conditions except oxidative degradations. The method has proven specificity for stability indicating assay method. PMID:25425754

Inter-day Reliability of the IDEEA Activity Monitor for Measuring Movement and Non-Movement Behaviors in Older Adults.

PubMed

de la Cámara, Miguel Ángel; Higueras-Fresnillo, Sara; Martinez-Gomez, David; Veiga, Oscar L

2018-05-29

The inter-day reliability of the Intelligent Device for Energy Expenditure and Activity (IDEEA) has not been studied to date. The study purpose was to examine the inter-day variability and reliability on two consecutive days collected with the IDEEA, as well as to predict the number of days needed to provide a reliable estimate of several movement (walking and climbing stairs) and non-movement behaviors (lying, reclining, sitting) and standing in older adults. The sample included 126 older adults (74 women) who wore the IDEEA for 48-h. Results showed low variability between the two days and its reliability was from moderate (ICC=0.34) to high (ICC=0.80) in most of movement and non-movement behaviors analyzed. The Bland-Altman plots showed a high-moderate agreement between days and the Spearman-Brown formula estimated ranged from 1.2 and 9.1 days of monitoring with the IDEEA are needed to achieve ICCs≥0.70 in older adults for sitting and climbing stairs, respectively.

Quantitative high-throughput determination of endogenous retinoids in human plasma using triple-stage liquid chromatography/tandem mass spectrometry.

PubMed

Gundersen, Thomas E; Bastani, Nasser E; Blomhoff, Rune

2007-01-01

A high-throughput ultrasensitive analytical method based on liquid chromatography with positive ion atmospheric pressure chemical ionization (APCI) coupled to tandem mass spectrometric detection (LC/MS/MS) was developed for the determination of all-trans-4-oxo-retinoic acid (at4oxoRA), 13-cis-4-oxo-retinoic acid (13c4oxoRA), 13-cis-retinoic acid (13cRA), all-trans-retinoic acid (atRA) and all-trans-retinol (atROH) in human plasma. A stable isotope of atRA was used as internal standard (IS). The analytes and IS were isolated from 100 microL plasma by acetonitrile mono-phase extraction (MPE) performed in black 96-well microtiterplates. A 100 microL injection was focused on-column and chromatographed on an Agilent ZORBAX SB-C18 rapid-resolution high-throughput (RRHT) column with 1.8-microm particles (4.6 mmx50 mm) maintained at 60 degrees C. The initial mobile phase composition was acetonitrile/water/formic acid (10:90:0.1, v/v/v) delivered at 1.8 mL/min. Elution was accomplished by a fast gradient to acetonitrile/methanol/formic acid (90:10:0.1, v/v/v). The method had a chromatographic total run time of 7 min. An Applied Biosystems 4000 Q TRAP linear tandem mass spectrometer equipped with a heated nebulizer (APCI) ionization source was operated in multiple reaction monitoring (MRM) mode with the precursor-to-product ion transitions m/z 315.4-->297 (4-oxo-retinoic acids), 301.2-->205 (retinoic acids), 305.0-->209 (IS) and 269.2-->93 (retinol) used for quantification. The assay was fully validated and found to have acceptable accuracy, precision, linearity, sensitivity and selectivity. The mean extraction recoveries from spiked plasma samples were 80-105% for the various retinoids at three different levels. The intra-day accuracy of the assay was within 8% of nominal and intra-day precision was better than 8% coefficient of variance (CV) for retinoic acids. Inter-day precision results for quality control samples run over a 12-day period alongside clinical samples showed mean precision better than 12.5% CV. The limit of quantification was in the range of 0.1-0.2 ng/mL and the mass limit of detection (mLOD) was in the range 1-4 pg on column for the retinoic acids. The assay has been successfully applied to the analysis of 1700 plasma samples. Copyright (c) 2007 John Wiley & Sons, Ltd.

Development and validation of an OECD reproductive toxicity test guideline with the pond snail Lymnaea stagnalis (Mollusca, Gastropoda).

PubMed

Ducrot, Virginie; Askem, Clare; Azam, Didier; Brettschneider, Denise; Brown, Rebecca; Charles, Sandrine; Coke, Maïra; Collinet, Marc; Delignette-Muller, Marie-Laure; Forfait-Dubuc, Carole; Holbech, Henrik; Hutchinson, Thomas; Jach, Arne; Kinnberg, Karin L; Lacoste, Cédric; Le Page, Gareth; Matthiessen, Peter; Oehlmann, Jörg; Rice, Lynsey; Roberts, Edward; Ruppert, Katharina; Davis, Jessica Elphinstone; Veauvy, Clemence; Weltje, Lennart; Wortham, Ruth; Lagadic, Laurent

2014-12-01

The OECD test guideline development program has been extended in 2011 to establish a partial life-cycle protocol for assessing the reproductive toxicity of chemicals to several mollusk species, including the great pond snail Lymnaea stagnalis. In this paper, we summarize the standard draft protocol for a reproduction test with this species, and present inter-comparison results obtained in a 56-day prevalidation ring-test using this protocol. Seven European laboratories performed semi-static tests with cultured snails of the strain Renilys® exposed to nominal concentrations of cadmium chloride (from 53 to 608μgCdL(-1)). Cd concentrations in test solutions were analytically determined to confirm accuracy in the metal exposure concentrations in all laboratories. Physico-chemical and biological validity criteria (namely dissolved oxygen content >60% ASV, water temperature 20±1°C, control snail survival >80% and control snail fecundity >8 egg-masses per snail over the test period) were met in all laboratories which consistently demonstrated the reproductive toxicity of Cd in snails using the proposed draft protocol. Effect concentrations for fecundity after 56days were reproducible between laboratories (68

Development and validation of a novel, simple, and accurate spectrophotometric method for the determination of lead in human serum.

PubMed

Shayesteh, Tavakol Heidari; Khajavi, Farzad; Khosroshahi, Abolfazl Ghafuri; Mahjub, Reza

2016-01-01

The determination of blood lead levels is the most useful indicator of the determination of the amount of lead that is absorbed by the human body. Various methods, like atomic absorption spectroscopy (AAS), have already been used for the detection of lead in biological fluid, but most of these methods are based on complicated, expensive, and highly instructed instruments. In this study, a simple and accurate spectroscopic method for the determination of lead has been developed and applied for the investigation of lead concentration in biological samples. In this study, a silica gel column was used to extract lead and eliminate interfering agents in human serum samples. The column was washed with deionized water. The pH was adjusted to the value of 8.2 using phosphate buffer, and then tartrate and cyanide solutions were added as masking agents. The lead content was extracted into the organic phase containing dithizone as a complexion reagent and the dithizone-Pb(II) complex was formed and approved by visible spectrophotometry at 538 nm. The recovery was found to be 84.6 %. In order to validate the method, a calibration curve involving the use of various concentration levels was calculated and proven to be linear in the range of 0.01-1.5 μg/ml, with an R (2) regression coefficient of 0.9968 by statistical analysis of linear model validation. The largest error % values were found to be -5.80 and +11.6 % for intra-day and inter-day measurements, respectively. The largest RSD % values were calculated to be 6.54 and 12.32 % for intra-day and inter-day measurements, respectively. Further, the limit of detection (LOD) was calculated to be 0.002 μg/ml. The developed method was applied to determine the lead content in the human serum of voluntary miners, and it has been proven that there is no statistically significant difference between the data provided from this novel method and the data obtained from previously studied AAS.

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

PubMed

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

2011-07-01

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

Use of multiresponse statistical techniques to optimize the separation of diosmin, hesperidin, diosmetin and hesperitin in different pharmaceutical preparations by high performance liquid chromatography with UV-DAD.

PubMed

Sammani, Mohamad Subhi; Clavijo, Sabrina; Portugal, Lindomar; Suárez, Ruth; Seddik, Hassan; Cerdà, Víctor

2017-05-15

A new method for the separation and determination of four flavonoids: hesperidin (HES), diosmin (DIO), hesperitin (HTIN), and diosmetin (DTIN) in pure form and pharmaceutical formulations has been developed by using high performance liquid chromatography (HPLC) with UV-DAD detection. Multivariate statistics (2 k full factorial and Box Behnken Designs) has been used for the multiresponse optimization of the chromatographic separation, which was completed in 22min, and carried out on a symmetry® C18 column (250×3mm; 5µm) as stationary phase. Separation was conducted by gradient elution mode using a mixture of methanol, acetonitrile and water pH: 2.5 (CH 3 COOH), as mobile phase. Analytes were separated setting the column at 22°C, with a flow rate of 0.58mLmin -1 and detected at 285nm. Under the optimized conditions, the flavonoids showed retention times of: 8.62, 11.53, 18.55 and 19.94min for HES, DIO, HTIN and DTIN, respectively. Limits of detection and quantification were <0.0156µgmL -1 and <0.100µgmL -1 , respectively. Linearity was achieved with good correlation coefficients values (r 2 =0.999; n=5). Intra-day and inter-day precision were found to be less than 3.44% (n=7). Finally, the proposed method was successfully applied to determine the target flavonoids in pharmaceutical preparations with satisfactory recoveries (between 95.2% and 107.9%), demonstrating that should also find application in the quality control, as well as in the pharmacokinetic studies of these drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed

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

2013-02-01

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

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

PubMed

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

2017-10-15

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

Validation of a multi-analyte HPLC-DAD method for determination of uric acid, creatinine, homovanillic acid, niacinamide, hippuric acid, indole-3-acetic acid and 2-methylhippuric acid in human urine.

PubMed

Remane, Daniela; Grunwald, Soeren; Hoeke, Henrike; Mueller, Andrea; Roeder, Stefan; von Bergen, Martin; Wissenbach, Dirk K

2015-08-15

During the last decades exposure sciences and epidemiological studies attracts more attention to unravel the mechanisms for the development of chronic diseases. According to this an existing HPLC-DAD method for determination of creatinine in urine samples was expended for seven analytes and validated. Creatinine, uric acid, homovanillic acid, niacinamide, hippuric acid, indole-3-acetic acid, and 2-methylhippuric acid were separated by gradient elution (formate buffer/methanol) using an Eclipse Plus C18 Rapid Resolution column (4.6mm×100mm). No interfering signals were detected in mobile phase. After injection of blank urine samples signals for the endogenous compounds but no interferences were detected. All analytes were linear in the selected calibration range and a non weighted calibration model was chosen. Bias, intra-day and inter-day precision for all analytes were below 20% for quality control (QC) low and below 10% for QC medium and high. The limits of quantification in mobile phase were in line with reported reference values but had to be adjusted in urine for homovanillic acid (45mg/L), niacinamide 58.5(mg/L), and indole-3-acetic acid (63mg/L). Comparison of creatinine data obtained by the existing method with those of the developed method showing differences from -120mg/L to +110mg/L with a mean of differences of 29.0mg/L for 50 authentic urine samples. Analyzing 50 authentic urine samples, uric acid, creatinine, hippuric acid, and 2-methylhippuric acid were detected in (nearly) all samples. However, homovanillic acid was detected in 40%, niacinamide in 4% and indole-3-acetic acid was never detected within the selected samples. Copyright © 2015 Elsevier B.V. All rights reserved.

High-precision two-way optic-fiber time transfer using an improved time code.

PubMed

Wu, Guiling; Hu, Liang; Zhang, Hao; Chen, Jianping

2014-11-01

We present a novel high-precision two-way optic-fiber time transfer scheme. The Inter-Range Instrumentation Group (IRIG-B) time code is modified by increasing bit rate and defining new fields. The modified time code can be transmitted directly using commercial optical transceivers and is able to efficiently suppress the effect of the Rayleigh backscattering in the optical fiber. A dedicated codec (encoder and decoder) with low delay fluctuation is developed. The synchronization issue is addressed by adopting a mask technique and combinational logic circuit. Its delay fluctuation is less than 27 ps in terms of the standard deviation. The two-way optic-fiber time transfer using the improved codec scheme is verified experimentally over 2 m to100 km fiber links. The results show that the stability over 100 km fiber link is always less than 35 ps with the minimum value of about 2 ps at the averaging time around 1000 s. The uncertainty of time difference induced by the chromatic dispersion over 100 km is less than 22 ps.

Multiresidue method for the determination of 77 pesticides in wine using QuEChERS sample preparation and gas chromatography with mass spectrometry.

PubMed

Jiang, Y; Li, X; Xu, J; Pan, C; Zhang, J; Niu, W

2009-06-01

A method based on a QuEChERS (quick, easy, cheap, effective, rugged, safe) sample preparation method and gas chromatography with mass spectrometric detection by selected ion monitoring (GC/MS-SIM) was developed for simultaneous determination of 77 pesticide residues in wine. An extraction of 10 ml of sample with acetonitrile followed by liquid-liquid partition formed by the addition of 4 g MgSO(4) and 3 g NaCl was applied in the sample preparation. The clean-up was carried out by applying dispersive solid-phase with 150 mg MgSO(4) as well as 50 mg primary secondary amine (PSA). One quantitation ion and at least two identification ions were selected in the analytical method for each pesticide compound by GC/MS. The recovery data were obtained by spiking blank samples at two concentration levels (0.05 and 0.2 mg l(-1)). The recoveries of all pesticides were in the range 70-110%, with intra-day precision of less than 15%, and the inter-day precision of less than 22% and 15% for 0.05 and 0.2 mg l(-1) fortification levels, respectively. Linearity was between 0.02 and 2 mg l(-1) with determination coefficients (R(2)) greater than 0.98 for all compounds. The limits of quantification (LOQs) for the 77 pesticides ranged from 0.003 to 0.05 mg l(-1). This method was applied for routine analysis in market products.

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.

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

PubMed

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

2014-11-07

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

Development and validation of a stability-indicating gas chromatographic method for quality control of residual solvents in blonanserin: a novel atypical antipsychotic agent.

PubMed

Peng, Ming; Liu, Jin; Lu, Dan; Yang, Yong-Jian

2012-09-01

Blonanserin is a novel atypical antipsychotic agent for the treatment of schizophrenia. Ethyl alcohol, isopropyl alcohol and toluene are utilized in the synthesis route of this bulk drug. A new validated gas chromatographic (GC) method for the simultaneous determination of residual solvents in blonanserin is described in this paper. Blonanserin was dissolved in N, N-dimethylformamide to make a sample solution that was directly injected into a DB-624 column. A postrun oven temperature at 240°C for approximately 2 h after the analysis cycle was performed to wash out blonanserin residue in the GC column. Quantitation was performed by external standard analyses and the validation was carried out according to International Conference on Harmonization validation guidelines Q2A and Q2B. The method was shown to be specific (no interference in the blank solution), linear (correlation coefficients ≥0.99998, n = 10), accurate (average recoveries between 94.1 and 101.7%), precise (intra-day and inter-day precision ≤2.6%), sensitive (limit of detection ≤0.2 ng, and limit of quantitation ≤0.7 ng), robust (small variations of carrier gas flow, initial oven temperature, temperature ramping rate, injector and detector temperatures did not significantly affect the system suitability test parameters and peak areas) and stable (reference standard and sample solutions were stable over 48 h). This extensively validated method is ready to be used for the quality control of blonanserin.

Pesticide analysis in teas and chamomile by liquid chromatography and gas chromatography tandem mass spectrometry using a modified QuEChERS method: validation and pilot survey in real samples.

PubMed

Lozano, Ana; Rajski, Łukasz; Belmonte-Valles, Noelia; Uclés, Ana; Uclés, Samanta; Mezcua, Milagros; Fernández-Alba, Amadeo R

2012-12-14

This paper presents the validation of a modified QuEChERS method in four matrices - green tea, red tea, black tea and chamomile. The experiments were carried out using blank samples spiked with a solution of 86 pesticides (insecticides, fungicides and herbicides) at four levels - 10, 25, 50 and 100 μg/kg. The samples were extracted according to the citrate QuEChERS protocol; however, to reduce the amount of coextracted matrix compounds, calcium chloride was employed instead of magnesium sulphate in the clean-up step. The samples were analysed by LC-MS/MS and GC-MS/MS. Included in the scope of validation were: recovery, linearity, matrix effects, limits of detection and quantitation as well as intra-day and inter-day precision. The validated method was used in a real sample survey carried out on 75 samples purchased in ten different countries. In all matrices, recoveries of the majority of compounds were in the 70-120% range and were characterised by precision lower than 20%. In 85% of pesticide/matrix combinations the analytes can be detected quantitatively by the proposed method at the European Union Maximum Residue Level. The analysis of the real samples revealed that large number of teas and chamomiles sold in the European Union contain pesticides whose usage is not approved and also pesticides in concentrations above the EU MRLs. Copyright © 2012 Elsevier B.V. All rights reserved.

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.

Chemical profiling and quantification of Dan-Deng-Tong-Nao-capsule using ultra high performance liquid chromatography coupled with high resolution hybrid quadruple-orbitrap mass spectrometry.

PubMed

Lv, Xiao-Jing; Sun, Zhi; Wang, Pei-Le; Yang, Jing; Xu, Tan-Ye; Jia, Qing-Quan; Li, Da-Wei; Su, Fang-Yi; Zhu, Zhen-Feng; Kang, Jian; Zhang, Xiao-Jian

2018-01-30

Dan-Deng-Tong-Nao capsule (DDTN) was a traditional Chinese medicine (TCM) formula, and has been widely used for the treatment of stroke clinically which caused by blood stasis. However, the bioactive substances and mechanism are unclear because of the complex compositions in DDTN. In this research, An ultra high-performance liquid chromatography (UHPLC) coupled with hybrid quadruple-orbitrap mass spectrometry (Q-Orbitrap MS) method was utilized to identify the chemical constituents of DDTN. In total, 102 compounds including diterpenes, lactones, flavonoids, and phenolic acids were identified by the accurate masses and fragmentation pathways, and 18 of them were unambiguously determined by comparison of reference standards. Besides, 12 representative compounds were simultaneously quantification analyzed and successfully applified for detecting in 9 batches of DDTN samples by UHPLC-Q-Orbitrap MS in parallel reaction monitoring (PRM) mode. The proposed approach was validated to be satisfied in terms of linearity (0.9954-0.9999), LOD (0.771ng/mL), LOQ (2.568ng/mL), intra-day precision ( <2.68%), inter-day precision ( <4.52%), repeatability ( <2.96%), stability ( <3.21%), and recovery (94.6-105.5%). The results indicate that the method of combining UHPLC with Q-Orbitrap MS is practical and efficient for the chemical clarification in DDTN, and has great potential for the integrating quality control of other traditional Chinese medicines. Copyright © 2017 Elsevier B.V. All rights reserved.

A Fast and Validated Reversed-Phase HPLC Method for Simultaneous Determination of Simvastatin, Atorvastatin, Telmisartan and Irbesartan in Bulk Drugs and Tablet Formulations

PubMed Central

Alhazmi, Hassan A.; Alnami, Ahmed M.; Arishi, Mohammed A. A.; Alameer, Raad K.; Al Bratty, Mohammed; Rehman, Zia ur; Javed, Sadique A.; Arbab, Ismail A.

2017-01-01

The aim of this study was to develop and validate a fast and simple reversed-phase HPLC method for simultaneous determination of four cardiovascular agents—atorvastatin, simvastatin, telmisartan and irbesartan in bulk drugs and tablet oral dosage forms. The chromatographic separation was accomplished by using Symmetry C18 column (75 mm × 4.6 mm; 3.5 μ) with a mobile phase consisting of ammonium acetate buffer (10 mM; pH 4.0) and acetonitrile in a ratio 40:60 v/v. Flow rate was maintained at 1 mL/min up to 3.5 min, and then suddenly changed to 2 mL/min till the end of the run (7.5 min). The data was acquired using ultraviolet detector monitored at 220 nm. The method was validated for linearity, precision, accuracy and specificity. The developed method has shown excellent linearity (R2 > 0.999) over the concentration range of 1–16 µg/mL. The limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.189–0.190 and 0.603–0.630 µg/mL, respectively. Inter-day and intra-day accuracy and precision data were recorded in the acceptable limits. The new method has successfully been applied for quantification of all four drugs in their tablet dosage forms with percent recovery within 100 ± 2%. PMID:29257120

Inter-Tester Reliability and Precision of Manual Muscle Testing and Hand-Held Dynamometry in Lower Limb Muscles of Children with Spina Bifida

ERIC Educational Resources Information Center

Mahony, Kate; Hunt, Adrienne; Daley, Deborah; Sims, Susan; Adams, Roger

2009-01-01

Reliability and measurement precision of manual muscle testing (MMT) and hand-held dynamometry (HHD) were compared for children with spina bifida. Strength measures were obtained of the hip flexors, hip abductors, and knee extensors of 20 children (10 males, 10 females; mean age 9 years 10 months; range: 5 to 15 years) by two experienced physical…

Precision and Deviation Comparison Between Icesat and Envisat in Typical Ice Gaining and Losing Regions of Antarctica

NASA Astrophysics Data System (ADS)

Du, W.; Chen, L.; Xie, H.; Hai, G.; Zhang, S.; Tong, X.

2017-09-01

This paper analyzes the precision and deviation of elevations acquired from Envisat and The Ice, Cloud and Land Elevation Satellite (ICESat) over typical ice gaining and losing regions, i.e. Lambert-Amery System (LAS) in east Antarctica, and Amundsen Sea Sector (ASS) in west Antarctica, during the same period from 2003 to 2008. We used GLA12 dataset of ICESat and Level 2 data of Envisat. Data preprocessing includes data filtering, projection transformation and track classification. Meanwhile, the slope correction is applied to Envisat data and saturation correction for ICESat data. Then the crossover analysis was used to obtain the crossing points of the ICESat tracks, Envisat tracks and ICESat-Envisat tracks separately. The two tracks we chose for cross-over analysis should be in the same campaign for ICESat (within 33 days) or the same cycle for Envisat (within 35 days).The standard deviation of a set of elevation residuals at time-coincident crossovers is calculated as the precision of each satellite while the mean value is calculated as the deviation of ICESat-Envisat. Generally, the ICESat laser altimeter gets a better precision than the Envisat radar altimeter. For Amundsen Sea Sector, the ICESat precision is found to vary from 8.9 cm to 17 cm and the Envisat precision varies from 0.81 m to 1.57 m. For LAS area, the ICESat precision is found to vary from 6.7 cm to 14.3 cm and the Envisat precision varies from 0.46 m to 0.81 m. Comparison result between Envisat and ICESat elevations shows a mean difference of 0.43 ±7.14 m for Amundsen Sea Sector and 0.53 ± 1.23 m over LAS.

Imaging of Herniated Discs of the Cervical Spine: Inter-Modality Differences between 64-Slice Multidetector CT and 1.5-T MRI

PubMed Central

Yi, Ji Sook; Han, Jong Kyu; Kim, Hyun-Joo

2015-01-01

Objective To assess inter-modality variability when evaluating cervical intervertebral disc herniation using 64-slice multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI). Materials and Methods Three musculoskeletal radiologists independently reviewed cervical spine 1.5-T MRI and 64-slice MDCT data on C2-3 though C6-7 of 51 patients in the context of intervertebral disc herniation. Interobserver and inter-modality agreements were expressed as unweighted kappa values. Weighted kappa statistics were used to assess the extents of agreement in terms of the number of involved segments (NIS) in disc herniation and epicenter measurements collected using MDCT and MRI. Results The interobserver agreement rates upon evaluation of disc morphology by the three radiologists were in fair to moderate agreement (k = 0.39-0.53 for MDCT images; k = 0.45-0.56 for MRIs). When the disc morphology was categorized into two and four grades, the inter-modality agreement rates were moderate (k-value, 0.59) and substantial (k-value, 0.66), respectively. The inter-modality agreements for evaluations of the NIS (k-value, 0.78) and the epicenter (k-value, 0.79) were substantial. Also, the interobserver agreements for the NIS (CT; k-value, 0.85 and MRI; k-value, 0.88) and epicenter (CT; k-value, 0.74 and MRI; k-value, 0.70) evaluations by two readers were substantial. MDCT tended to underestimate the extent of herniated disc lesions compared with MRI. Conclusion Multidetector-row computed tomography and MRI showed a moderate-to-substantial degree of inter-modality agreement for the assessment of herniated cervical discs. MDCT images have a tendency to underestimate the anterior/posterior extent of the herniated disc compared with MRI. PMID:26175589

2H NMR and 13C-IRMS analyses of acetic acid from vinegar, 18O-IRMS analysis of water in vinegar: international collaborative study report.

PubMed

Thomas, Freddy; Jamin, Eric

2009-09-01

An international collaborative study of isotopic methods applied to control the authenticity of vinegar was organized in order to support the recognition of these procedures as official methods. The determination of the 2H/1H ratio of the methyl site of acetic acid by SNIF-NMR (site-specific natural isotopic fractionation-nuclear magnetic resonance) and the determination of the 13C/12C ratio, by IRMS (isotope ratio mass spectrometry) provide complementary information to characterize the botanical origin of acetic acid and to detect adulterations of vinegar using synthetic acetic acid. Both methods use the same initial steps to recover pure acetic acid from vinegar. In the case of wine vinegar, the determination of the 18O/16O ratio of water by IRMS allows to differentiate wine vinegar from vinegars made from dried grapes. The same set of vinegar samples was used to validate these three determinations. The precision parameters of the method for measuring delta13C (carbon isotopic deviation) were found to be similar to the values previously obtained for similar methods applied to wine ethanol or sugars extracted from fruit juices: the average repeatability (r) was 0.45 per thousand, and the average reproducibility (R) was 0.91 per thousand. As expected from previous in-house study of the uncertainties, the precision parameters of the method for measuring the 2H/1H ratio of the methyl site were found to be slightly higher than the values previously obtained for similar methods applied to wine ethanol or fermentation ethanol in fruit juices: the average repeatability was 1.34 ppm, and the average reproducibility was 1.62 ppm. This precision is still significantly smaller than the differences between various acetic acid sources (delta13C and delta18O) and allows a satisfactory discrimination of vinegar types. The precision parameters of the method for measuring delta18O were found to be similar to the values previously obtained for other methods applied to wine and fruit juices: the average repeatability was 0.15 per thousand, and the average reproducibility was 0.59 per thousand. The above values are proposed as repeatability and reproducibility limits in the current state of the art. On the basis of this satisfactory inter-laboratory precision and on the accuracy demonstrated by a spiking experiment, the authors recommend the adoption of the three isotopic determinations included in this study as official methods for controlling the authenticity of vinegar.

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

PubMed

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

2016-02-15

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

Comparison of the quantification of acetaminophen in plasma, cerebrospinal fluid and dried blood spots using high-performance liquid chromatography-tandem mass spectrometry

PubMed Central

Taylor, Rachel R.; Hoffman, Keith L.; Schniedewind, Björn; Clavijo, Claudia; Galinkin, Jeffrey L.; Christians, Uwe

2013-01-01

Acetaminophen (paracetamol, N-(4-hydroxyphenyl) acetamide) is one of the most commonly prescribed drugs for the management of pain in children. Quantification of acetaminophen in pre-term and term neonates and small children requires the availability of highly sensitive assays in small volume blood samples. We developed and validated an LC-MS/MS assay for the quantification of acetaminophen in human plasma, cerebro-spinal fluid (CSF) and dried blood spots (DBS). Reconstitution in water (DBS only) and addition of a protein precipitation solution containing the deuterated internal standard were the only manual steps. Extracted samples were analyzed on a Kinetex 2.6 μm PFP column using an acetonitrile/formic acid gradient. The analytes were detected in the positive multiple reaction mode. Alternatively, DBS were automatically processed using direct desorption in a sample card and preparation (SCAP) robotic autosampler in combination with online extraction. The range of reliable response in plasma and CSF was 3.05-20,000 ng/ml (r2 > 0.99) and 27.4-20,000 ng/ml (r2 > 0.99) for DBS (manual extraction and automated direct desorption). Inter-day accuracy was always within 85-115% and inter-day precision for plasma, CSF and manually extracted DBS were less than 15%. Deming regression analysis comparing 167 matching pairs of plasma and DBS samples showed a correlation coefficient of 0.98. Bland Altman analysis indicated a 26.6% positive bias in DBS, most likely reflecting the blood: plasma distribution ratio of acetaminophen. DBS are a valid matrix for acetaminophen pharmacokinetic studies. PMID:23670126

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

PubMed

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

2008-11-01

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

Comprehensive determination of flavouring additives and nicotine in e-cigarette refill solutions. Part I: Liquid chromatography-tandem mass spectrometry analysis.

PubMed

Aszyk, Justyna; Kubica, Paweł; Kot-Wasik, Agata; Namieśnik, Jacek; Wasik, Andrzej

2017-10-13

Liquid chromatography-tandem mass spectrometry with electrospray ionization (HPLC-ESI-MS/MS) methods were developed for the simultaneous determination of 42 flavouring compounds and nicotine in liquids for e-cigarettes. The chromatographic separation was performed using an Ace ® Ultracore™ SuperC18™ (100×2.1mm, 2.5μm) column in both acidic and alkaline pH conditions to separate all the compounds. A simple "dilute & shoot" approach was used for the sample preparation. The method validation was performed by evaluating key analytical parameters such as linearity, accuracy, selectivity, precision, limit of detection (LOD) and limit of quantification (LOQ). The calibration curves showed good linearity within the specific ranges for the investigated compounds with correlation coefficients greater than 0.990 in each case. The recovery for all the investigated compounds varied from 89% to 110%. The intra- and inter-day precision were within the acceptable limits (±15%) at all tested concentrations. The applicability of the methods was examined by analysing 25 liquid samples from e-cigarettes commercially available on the Polish market. Copyright © 2017 Elsevier B.V. All rights reserved.

Development and validation of a high throughput assay for the quantification of multiple green tea-derived catechins in human plasma.

PubMed

Mawson, Deborah H; Jeffrey, Keon L; Teale, Philip; Grace, Philip B

2018-06-19

A rapid, accurate and robust method for the determination of catechin (C), epicatechin (EC), gallocatechin (GC), epigallocatechin (EGC), catechin gallate (Cg), epicatechin gallate (ECg), gallocatechin gallate (GCg) and epigallocatechin gallate (EGCg) concentrations in human plasma has been developed. The method utilises protein precipitation following enzyme hydrolysis, with chromatographic separation and detection using reversed-phase liquid chromatography - tandem mass spectrometry (LC-MS/MS). Traditional issues such as lengthy chromatographic run times, sample and extract stability, and lack of suitable internal standards have been addressed. The method has been evaluated using a comprehensive validation procedure, confirming linearity over appropriate concentration ranges, and inter/intra batch precision and accuracies within suitable thresholds (precisions within 13.8% and accuracies within 12.4%). Recoveries of analytes were found to be consistent between different matrix samples, compensated for using suitable internal markers and within the performance of the instrumentation used. Similarly, chromatographic interferences have been corrected using the internal markers selected. Stability of all analytes in matrix is demonstrated over 32 days and throughout extraction conditions. This method is suitable for high throughput sample analysis studies. This article is protected by copyright. All rights reserved.

Relative importance of precipitation frequency and intensity in inter-annual variation of precipitation in Singapore during 1980-2013

NASA Astrophysics Data System (ADS)

Li, Xin; Babovic, Vladan

2017-04-01

Observed studies on inter-annual variation of precipitation provide insight into the response of precipitation to anthropogenic climate change and natural climate variability. Inter-annual variation of precipitation results from the concurrent variations of precipitation frequency and intensity, understanding of the relative importance of frequency and intensity in the variability of precipitation can help fathom its changing properties. Investigation of the long-term changes of precipitation schemes has been extensively carried out in many regions across the world, however, detailed studies of the relative importance of precipitation frequency and intensity in inter-annual variation of precipitation are still limited, especially in the tropics. Therefore, this study presents a comprehensive framework to investigate the inter-annual variation of precipitation and the dominance of precipitation frequency and intensity in a tropical urban city-state, Singapore, based on long-term (1980-2013) daily precipitation series from 22 rain gauges. First, an iterative Mann-Kendall trend test method is applied to detect long-term trends in precipitation total, frequency and intensity at both annual and seasonal time scales. Then, the relative importance of precipitation frequency and intensity in inducing the inter-annual variation of wet-day precipitation total is analyzed using a dominance analysis method based on linear regression. The results show statistically significant upward trends in wet-day precipitation total, frequency and intensity at annual time scale, however, these trends are not evident during the monsoon seasons. The inter-annual variation of wet-day precipitation is mainly dominated by precipitation intensity for most of the stations at annual time scale and during the Northeast monsoon season. However, during the Southwest monsoon season, the inter-annual variation of wet-day precipitation is mainly dominated by precipitation frequency. These results have implications for water resources management practices in Singapore.

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

PubMed

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

2017-04-07

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

The reliability and validity of the Turkish version of Fullerton Advanced Balance (FAB-T) scale.

PubMed

Iyigun, Gozde; Kirmizigil, Berkiye; Angin, Ender; Oksuz, Sevim; Can, Filiz; Eker, Levent; Rose, Debra J

2018-06-04

The aim of this study was to evaluate the reliability and validity of the Turkish version of the FAB(FAB-T) scale in the older Turkish adults. The reliability and validity of the scale was tested on 200 community-dwelling older adults. FAB-T scale was scored by different physiotherapists on different days to evaluate inter-rater and intrarater reliability. The Berg Balance Scale (BBS) was used for the evaluation of convergent validity, and the content validity of the FAB-T scale was investigated. The FAB-T scale showed very high inter- and intra-rater reliability. For inter-rater agreement, on the individual test items and total score ICC values were 0.92 (95 %CI; 0.90-0.94) and 0.96 (95% CI; 0.95-0.97) respectively. The intra-rater agreement, on the individual test items and total score ICC values were 0.93 (95 %CI; 0.91- 0.95) and 0.96 (95% CI; 0.95- 0.97) respectively. There was a good agreement between the FAB-T and BBS scales. A high correlation was found between the BBS and FAB-T scales [rho = 0.70 (%95 CI; 0.62-0.76)] indicating good convergent validity. Considering the content validity of the FAB-T scale, no floor (floor score: 0%) or ceiling (ceiling score: 6.5%) effect was detected. The FAB-T scale was successfully translated from the original English version (FAB) and demonstrated strong psychometric features. It was found that the FAB-T scale has very high inter-rater and intra-rater reliability. Considering the convergent validity, the scale has high correlation with the BBS. The FAB-T has no floor and ceiling effect. Copyright © 2018 Elsevier B.V. All rights reserved.

validated microbiological and HPLC methods for the determination of moxifloxacin in pharmaceutical preparations and human plasma.

PubMed

Abdelaziz, Ahmed A; Elbanna, Tarek E; Gamaleldeen, Noha M

2012-10-01

The article presents a comparison between microbiological and high performance liquid chromatographic (HPLC) assays for quantification of moxifloxacin in tablets, ophthalmic solutions and human plasma. The microbiological method employed a cylinder-plate agar diffusion assay using a strain of Esherichia coli ATCC 25922 as the test organism and phosphate buffer (pH8) as the diluent. The calibration curves were linear (R(2) > 0.98) over a concentration range of 0.125 to 16 µgml(-1). The within day and between days precisions were ≤ 4.47% and ≤ 6.39% respectively. Recovery values were between 89.4 and 110.2%. The HPLC assay used Hypersil(®) BDS C18 reversed phase column (250×4.6 mm, 5µm) with a mobile phase comprising 20 mM ammonium dihydrogen orthophosphate (pH3) and acetonitrile (75:25) and flowing at 1.5 ml/min. The detection was at 295nm. The calibration curves were linear (R(2) > 0.999) over the range of 0.125 to 16 µg ml(-1). The within day and between days precisions were ≤ 4.07% and ≤ 5.09% respectively. Recovery values were between 97.7 and 107.6%. Similar potencies were obtained after the analysis of moxifloxacin tablets and ophthalmic solutions by both methods. Also pharmacokinetic parameters were calculated after the analysis of plasma samples of six male healthhy volunteers by both validated methods.

Quantitative analysis of iridoids, secoiridoids, xanthones and xanthone glycosides in Gentiana lutea L. roots by RP-HPLC and LC-MS.

PubMed

Aberham, Anita; Schwaiger, Stefan; Stuppner, Hermann; Ganzera, Markus

2007-11-05

The here described HPLC-method enables the determination of all major, currently known bioactive compounds in gentian roots. A separation of iridoids (loganic acid), secoiridoids (swertiamarin, gentiopicroside, amarogentin, sweroside), xanthones (gentisin, isogentisin) and two xanthone glycosides (gentiosides) was possible on RP-18 column material, using 0.025% aqueous TFA, acetonitrile and n-propanol as mobile phase. The method is sensitive (LOD

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

PubMed

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

2015-03-25

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

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

PubMed

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

2005-07-01

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

Multi-mycotoxin stable isotope dilution LC-MS/MS method for Fusarium toxins in beer.

PubMed

Habler, Katharina; Gotthardt, Marina; Schüler, Jan; Rychlik, Michael

2017-03-01

A stable isotope dilution LC-MS/MS multi-mycotoxin method was developed for 12 different Fusarium toxins including modified mycotoxins in beer (deoxynivalenol-3-glucoside, deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyl-deoxynivalenol, HT2-toxin, T2-toxin, enniatin B, B1, A1, A, beauvericin and zearalenone). As sample preparation and purification of beer a combined solid phase extraction for trichothecenes, enniatins, beauvericin and zearalenone was firstly developed. The validation of the new method gave satisfying results: intra-day and inter-day precision and recoveries were 1-5%, 2-8% and 72-117%, respectively. In total, 61 different organic and conventional beer samples from Germany and all over the world were analyzed by using the newly developed multi-mycotoxin method. In summary, deoxynivalenol, deoxynivalenol-3-glucoside, 3-acetyldeoxynivaleneol and enniatin B were quantified in rather low contents in the investigated beer samples. None of the other monitored Fusarium toxins like 15-acetyldeoxynivalenol, HT2- and T2-toxin, zearalenone, enniatin B1, A1, A or beauvericin were detectable. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mycotoxin contamination in laboratory rat feeds and their implications in animal research.

PubMed

Escrivá, Laura; Font, Guillermina; Berrada, Houda; Manyes, Lara

2016-09-01

Compound feed is particularly vulnerable to multi-mycotoxin contamination. A method for the determination of 12 mycotoxins; enniatins A, A1, B, B1; aflatoxins B1, B2, G1, G2; OTA; ZEA; T-2 and HT-2 by liquid chromatography-tandem mass spectrometry has been developed and applied for the analysis of laboratory rat commercial feeds. The method trueness was checked by recovery assays at three different spiked levels (n = 9). Recoveries ranged from 73% to 112%, and the intra-day and inter-day precision were lower than 9% and 13%, respectively. Limits of quantitation were lower than 15 μg/kg. Twenty-seven laboratory rats feed samples showed multi-contamination by at least three up to six different mycotoxins. ENNs B and B1, followed by ZEA were the most prevalent mycotoxins. T-2, HT-2, and OTA were not detected. ZEA showed the highest concentration levels reaching 492 μg/kg. The results underline the importance of implementing mycotoxin regular surveillance programs for laboratory animal feeds.

Optimization and Validation of a Plaque Reduction Neutralization Test for the Detection of Neutralizing Antibodies to Four Serotypes of Dengue Virus Used in Support of Dengue Vaccine Development

PubMed Central

Timiryasova, Tatyana M.; Bonaparte, Matthew I.; Luo, Ping; Zedar, Rebecca; Hu, Branda T.; Hildreth, Stephen W.

2013-01-01

A dengue plaque reduction neutralization test (PRNT) to measure dengue serotype–specific neutralizing antibodies for all four virus serotypes was developed, optimized, and validated in accordance with guidelines for validation of bioanalytical test methods using human serum samples from dengue-infected persons and persons receiving a dengue vaccine candidate. Production and characterization of dengue challenge viruses used in the assay was standardized. Once virus stocks were characterized, the dengue PRNT50 for each of the four serotypes was optimized according to a factorial design of experiments approach for critical test parameters, including days of cell seeding before testing, percentage of overlay carboxymethylcellulose medium, and days of incubation post-infection to generate a robust assay. The PRNT50 was then validated and demonstrated to be suitable to detect and measure dengue serotype-specific neutralizing antibodies in human serum samples with acceptable intra-assay and inter-assay precision, accuracy/dilutability, specificity, and with a lower limit of quantitation of 10. PMID:23458954

[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.

Evaluation of the accuracy of Demirjian method for estimation of dental age among 6-12 years of children in Navi Mumbai: A radiographic study.

PubMed

Hegde, Rahul J; Khare, Sumedh Suhas; Saraf, Tanvi A; Trivedi, Sonal; Naidu, Sonal

2015-01-01

Dental formation is superior to eruption as a method of dental age (DA) assessment. Eruption is only a brief occurrence, whereas formation may be related at different chronologic age levels, thereby providing a precise index for determining DA. The study was designed to determine the nature of inter-relationship between chronologic and DA. Age estimation depending upon tooth formation was done by Demirjian method and accuracy of Demirjian method was also evaluated. The sample for the study consisted of 197 children of Navi Mumbai. Significant positive correlation was found between chronologic age and DA that is, (r = 0.995), (P < 0.0001) for boys and (r = 0.995), (P < 0.0001) for girls. When age estimation was done by Demirjian method, mean the difference between true age (chronologic age) and assessed (DA) was 2 days for boys and 37 days for girls. Demirjian method showed high accuracy when applied to Navi Mumbai (Maharashtra - India) population. Demirjian method showed high accuracy when applied to Navi Mumbai (Maharashtra - India) population.

Phytic acid-stabilized super-amphiphilic Fe3O4-graphene oxide for extraction of polycyclic aromatic hydrocarbons from vegetable oils.

PubMed

Ji, Wenhua; Zhang, Mingming; Duan, Wenjuan; Wang, Xiao; Zhao, Hengqiang; Guo, Lanping

2017-11-15

Phytic acid-stabilized Fe 3 O 4 -graphene oxide (GOPA@Fe 3 O 4 ) was assembled by microwave-enhanced hydrothermal synthesis and super-amphipathicity was demonstrated by measurement of dynamic oil and water contact angles. GOPA@Fe 3 O 4 was used as a sorbent for enrichment of eight polycyclic aromatic hydrocarbons (PAHs) from vegetable oils by magnetic solid-phase extraction (MSPE). The extraction-desorption factors were systematically investigated and, under optimum conditions, the super-amphiphilic sorbent achieved wide linear ranges (0.2-200ngg -1 ), satisfactory precision (3.44-6.64% for intra-day and 5.39-8.41% for inter-day) and low limits of detection (LODs, 0.06-0.15ngg -1 ) for PAHs. Excellent recoveries (85.6-102.3%) for spiked PAHs were obtained with genuine vegetable oil samples. These results indicate that MSPE using GOPA@Fe 3 O 4 as the sorbent, coupled with high performance liquid chromatography (HPLC), is an efficient and simple method for the detection of low concentrations of PAHs in vegetable oils. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Direct-injection HPLC method of measuring micafungin in human plasma using a novel hydrophobic/hydrophilic hybrid ODS column.

PubMed

Uranishi, Hiroaki; Nakamura, Mitsuhiro; Nakamura, Hiroki; Ikeda, Yukari; Otsuka, Mayuko; Kato, Zenichiro; Tsuchiya, Teruo

2011-04-15

A direct-injection HPLC-based method has been developed for determining amounts of micafungin in human plasma using a novel hydrophobic/hydrophilic hybrid ODS column. The method is easy to perform and requires only 10 μL of a filtered plasma sample. The chromatographic separations were carried out with a gradient mode. The fluorescence detection wavelengths of excitation and emission were set at 273 nm and 464 nm, respectively. Retention times for micafungin and IS were 22.4 and 23.7 min, respectively. Micafungin and FR195743 (IS) peaks were completely separated with little tailing, and no interference was observed. The calibration curve of micafungin showed good linearity in the range of 0.5-20.0 μg/mL (r(2)=1.00). The intra-day accuracy ranged from -4.5 to 5.3%. The inter-day accuracy ranged from -9.8 to 1.5%. The precisions were less than 10%. This method is useful for the determination of micafungin in human plasma. Copyright © 2011 Elsevier B.V. All rights reserved.

Up-and-down-shaker-assisted dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry for the determination of fungicides in wine.

PubMed

Chu, Shang-Ping; Tseng, Wan-Chi; Kong, Po-Hsin; Huang, Chun-Kai; Chen, Jung-Hsuan; Chen, Pai-Shan; Huang, Shang-Da

2015-10-15

An up-and-down-shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME) method coupled with gas chromatography-mass spectrometry was developed for the determination of fungicides (cyprodinil, procymidone, fludioxonil, flusilazole, benalaxyl, and tebuconazole) in wine. The developed method requires 11 μL of 1-octanol without the need for dispersive solvents. The total extraction time was approximately 3 min. Under optimum conditions, the linear range of the method was 0.05-100 μg L(-1) for all fungicides and the limit of detection was 0.007-0.025 μg L(-1). The absolute and relative recoveries were 31-83% and 83-107% for white wine, respectively, and 32-85% and 83-108% for red wine, respectively. The intra-day and inter-day precision were 0.5-7.5% and 0.7-6.1%, respectively. Our developed method had good sensitivity and high extraction efficiency. UDSA-DLLME is a desirable method in terms of performance and speed. Copyright © 2015 Elsevier Ltd. All rights reserved.

The construct validity of session RPE during an intensive camp in young male Karate athletes

PubMed Central

Padulo, Johnny; Chaabène, Helmi; Tabben, Montassar; Haddad, Monoem; Gevat, Cecilia; Vando, Stefano; Maurino, Lucio; Chaouachi, Anis; Chamari, Karim

2014-01-01

Summary Background: the aim of this study was to assess the validity of the session rating of perceived exertion (RPE) method and two objective HR-based methods for quantifying karate’s training load (TL) in young Karatekas. Methods: eleven athletes (age 12.50±1.84 years) participated in this study. The training period/camp was performed on 5 consecutive days with two training session (s) per-day (d). Construct validity of RPE method in young Karate athletes, was studied by correlation analysis between RPE session’s training load and both Edwards and Banister’s training impulse score’ method. Results: significant relationship was found between inter-day (n-11 × d-5 × s-2 = 110) sessions RPE and Edwards (r values from 0.84 to 0.92 p < 0.001) and Banister’s (r values from 0.84 to 0.97 p < 0.001), respectively Conclusion: this study showed that session-RPE can be considered a valid method for quantifying karate’s training load in young karate athletes. PMID:25332921

Evaluation of inter-day and inter-individual variability of tear peptide/protein profiles by MALDI-TOF MS analyses

PubMed Central

González, Nerea; Iloro, Ibon; Durán, Juan A.; Elortza, Félix

2012-01-01

Purpose To characterize the tear film peptidome and low molecular weight protein profiles of healthy control individuals, and to evaluate changes due to day-to-day and individual variation and tear collection methods, by using solid phase extraction coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling. Methods The tear protein profiles of six healthy volunteers were analyzed over seven days and inter-day and inter-individual variability was evaluated. The bilaterality of tear film and the effect of tear collection methods on protein profiles were also analyzed in some of these patients. MALDI-TOF MS analyses were performed on tear samples purified by using a solid phase extraction (SPE) method based on C18 functionalized magnetic beads for peptide and low molecular weight protein enrichment, focusing spectra acquisition on the 1 to 20 kDa range. Spectra were analyzed using principal component analysis (PCA) with MultiExperiment Viewer (TMeV) software. Volunteers were examined in terms of tear production status (Schirmer I test), clinical assessment of palpebral lids and meibomian glands, and a subjective OSD questionnaire before tear collection by a glass micro-capillary. Results Analysis of peptides and proteins in the 1–20 kDa range showed no significant inter-day differences in tear samples collected from six healthy individuals during seven days of monitoring, but revealed subtle intrinsic inter-individual differences. Profile analyses of tears collected from the right and left eyes confirmed tear bilaterality in four healthy patients. The addition of physiologic serum for tear sample collection did not affect the peptide and small protein profiles with respect to the number of resolved peaks, but it did reduce the signal intensity of the peaks, and increased variability. Magnetic beads were found to be a suitable method for tear film purification for the profiling study. Conclusions No significant variability in tear peptide and protein profiles below 20 kDa was found in healthy controls over a seven day period, nor in right versus left eye profiles from the same individual. Subtle inter-individual differences can be observed upon tear profiling analysis and confirm intrinsic variability between control subjects. Addition of physiologic serum for tear collection affects the proteome and peptidome in terms of peak intensities, but not in the composition of the profiles themselves. This work shows that MALDI-TOF MS coupled with C18 magnetic beads is an effective and reproducible methodology for tear profiling studies in the clinical monitoring of patients. PMID:22736947

Optimal mapping of site-specific multivariate soil properties.

PubMed

Burrough, P A; Swindell, J

1997-01-01

This paper demonstrates how geostatistics and fuzzy k-means classification can be used together to improve our practical understanding of crop yield-site response. Two aspects of soil are important for precision farming: (a) sensible classes for a given crop, and (b) their spatial variation. Local site classifications are more sensitive than general taxonomies and can be provided by the method of fuzzy k-means to transform a multivariate data set with i attributes measured at n sites into k overlapping classes; each site has a membership value mk for each class in the range 0-1. Soil variation is of interest when conditions vary over patches manageable by agricultural machinery. The spatial variation of each of the k classes can be analysed by computing the variograms of mk over the n sites. Memberships for each of the k classes can be mapped by ordinary kriging. Areas of class dominance and the transition zones between them can be identified by an inter-class confusion index; reducing the zones to boundaries gives crisp maps of dominant soil groups that can be used to guide precision farming equipment. Automation of the procedure is straightforward given sufficient data. Time variations in soil properties can be automatically incorporated in the computation of membership values. The procedures are illustrated with multi-year crop yield data collected from a 5 ha demonstration field at the Royal Agricultural College in Cirencester, UK.

Amino acid racemization dating of fossil bones, I. inter-laboratory comparison of racemization measurements

USGS Publications Warehouse

Bada, J.L.; Hoopes, E.; Darling, D.; Dungworth, G.; Kessels, H.J.; Kvenvolden, K.A.; Blunt, D.J.

1979-01-01

Enantiomeric measurements for aspartic acid, glutamic acid, and alanine in twenty-one different fossil bone samples have been carried out by three different laboratories using different analytical methods. These inter-laboratory comparisons demonstrate that D/L aspartic acid measurements are highly reproducible, whereas the enantiomeric measurements for the other amino acids show a wide variation between the three laboratories. At present, aspartic acid measurements are the most suitable for racemization dating of bone because of their superior analytical precision. ?? 1979.

Oxidative induction time -- A review of DSC experimental effects

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

Blaine, R.L.; Lundgren, C.J.; Harris, M.B.

1997-12-31

Over the past several years, a number of ASTM committees have explored a wide variety of experimental parameters affecting the oxidative induction time (OIT) test method in an attempt to improve its intra- and inter-laboratory precision. These studies have identified test temperature precision as a key parameter affecting OIT precision. Other parameters of importance are oxygen flow rate, specimen size, specimen pan type, oxygen pressure and catalyst effects. The work of Kuck, Bowmer, Riga, Tikuisis and Thomas are reviewed as well as the collective work of ASTM Committees E37, D2, D9 and D35.

Combined derivatization and high-performance liquid chromatography with fluorescence and ultraviolet detection for simultaneous analysis of octreotide and gabexate mesylate metabolite in human pancreatic juice samples.

PubMed

Carlucci, Giuseppe; Selvaggi, Federico; Sulpizio, Sara; Bassi, Claudio; Carlucci, Maura; Cotellese, Roberto; Ferrone, Vincenzo; Innocenti, Paolo; Locatelli, Marcello

2015-06-01

A simple and sensitive method based on the combination of derivatization and high-performance liquid chromatography with ultraviolet and fluorimetric detection was developed for the simultaneous determination of octreotide and gabexate mesylate metabolite in human pancreatic juice samples. Parameters of the derivatization procedure affecting extraction efficiency were optimized. The developed method was validated according to the International Conference on Harmonization guidelines. The calibration curves were linear over a range of 0.1-15 µg/mL for octreotide and 0.20-15 µg/mL for gabexate mesylate metabolite. Derivatized products of octreotide and gabexate mesylate metabolite were separated on a Luna C18 column (4.6 × 250 mm; 5 µm particle size) using a gradient with a run time of 36 min, without further purification. The limits of detection were 0.025 and 0.05, respectively, for octreotide and gabexate mesylate metabolite. This paper reports the validation of a quantitative high performance liquid chromatography-photodiode array-fluorescence (HPLC-PDA-FL) method for the simultaneous analysis of octreotide and gabexate mesylate metabolite in pancreatic juice by protein precipitation using zinc sulfate-methanol-acetonitrile containing the derivatizing reagent, 4-fluoro-7-nitro-[2,1,3]-benzoxadiazole (NBD-F). Derivatized products of octreotide and gabexate mesylate metabolite were separated on a Luna C18 column (4.6 × 250 mm; 5 µm particle size) using a gradient with a run time of 36 min, without further purification. The method was validated over the concentration ranges 0.1-15 and 0.2-15 µg/mL for octreotide and gabexate mesylate metabolite, respectively, in human pancreatic juice. Biphalin and methyl-p-hydroxybenzoate were used as the internal standards. This method was successfully utilized to support clinical studies in humans. The results from assay validations show that the method is selective, sensitive and robust. The limit of quantification of the method was 0.1 µg/mL for octreotide and 0.2 µg/mL for gabexate mesylate metabolite, and matrix matched standard curves showed a good linearity up to 15 µg/mL. In the entire analytical range the intra- and inter-day precision (RSD%) values were respectively ≤5.9% and ≤3.1% for octreotide and ≤2.0% and ≤3.9% for gabexate mesylate metabolite. For both analytes the intra- and inter-day accuracy (bias) values ranged respectively from -6.8 to -2.5% and from -4.6 to -5.7%. This method utilizes derivatization with NBD-F and provides adequate sensitivity for both drugs. Copyright © 2014 John Wiley & Sons, Ltd.

Living with chronic illness scale: international validation of a new self-report measure in Parkinson’s disease

PubMed Central

Ambrosio, Leire; Portillo, Mari Carmen; Rodríguez-Blázquez, Carmen; Rodriguez-Violante, Mayela; Castrillo, Juan Carlos Martínez; Arillo, Víctor Campos; Garretto, Nélida Susana; Arakaki, Tomoko; Dueñas, Marcos Serrano; Álvarez, Mario; Ibáñez, Ivonne Pedroso; Carvajal, Ana; Martínez-Martín, Pablo

2016-01-01

Understanding how a person lives with a chronic illness, such as Parkinson’s disease (PD), is necessary to provide individualized care and professionals role in person-centered care at clinical and community levels is paramount. The present study was aimed to analyze the psychometric properties of the Living with Chronic Illness-PD Scale (EC-PC) in a wide Spanish-speaking population with PD. International cross-sectional study with retest was carried out with 324 patients from four Latin American countries and Spain. Feasibility, acceptability, scaling assumptions, reliability, precision, and construct validity were tested. The study included 324 patients, with age (mean±s.d.) 66.67±10.68 years. None of the EC-PC items had missing values and all acceptability parameters fulfilled the standard criteria. Around two-third of the items (61.54%) met scaling assumptions standards. Concerning internal consistency, Cronbach’s alpha values were 0.68–0.88; item-total correlation was >0.30, except for two items; item homogeneity index was >0.30, and inter-item correlation values 0.14–0.76. Intraclass correlation coefficient for EC-PC stability was 0.76 and standard error of measurement (s.e.m.) for precision was 8.60 (for a EC-PC s.d.=18.57). EC-PC presented strong correlation with social support (rS=0.61) and moderate correlation with life satisfaction (rS=0.46). Weak and negligible correlations were found with the other scales. Internal validity correlations ranged from 0.46 to 0.78. EC-PC total scores were significantly different for each severity level based on Hoehn and Yahr and Clinical Impression of Severity Index, but not for Patient Global Impression of Severity. The EC-PC has satisfactory acceptability, reliability, precision, and validity to evaluate living with PD. PMID:28725703

Inter- and intratester reliability values of ultrasound imaging measurements of diaphragm movement in the thoracic and thoracolumbar curves in adolescent idiopathic scoliosis.

PubMed

Noh, Dong Koog; Koh, Jae-Hyun; You, Joshua Sung-H

2016-01-01

The purpose of this study was to determine intertester and intratester reliability of ultrasound measurements of bilateral diaphragm excursions in the thoracic and thoracolumbar spinal curves of 31 females with adolescent idiopathic scoliosis (AIS) (mean age = 14.1 ± 1.8 years). Subjects were tested during tidal breathing using real-time ultrasound imaging with a 3.5 MHz curvilinear transducer. There were no significant differences in intratester and intertester reliability values in bilateral diaphragmatic excursions measured at the thoracolumbar spinal curve, whereas significant differences were observed in measurements taken at the thoracic spinal curve (p < 0.05). Overall, the intertester and intratester reliabilities of the thoracic and thoracolumbar curves in AIS ranged from 0.764 to 0.998. These findings suggest that ultrasound imaging is highly reliable between and within testers and is useful to precisely discriminate pathological diaphragm movement in idiopathic thoracic scoliosis and idiopathic thoracolumbar scoliosis.

Continuous glucose monitoring in subcutaneous tissue using factory-calibrated sensors: a pilot study.

PubMed

Hoss, Udo; Jeddi, Iman; Schulz, Mark; Budiman, Erwin; Bhogal, Claire; McGarraugh, Geoffrey

2010-08-01

Commercial continuous subcutaneous glucose monitors require in vivo calibration using capillary blood glucose tests. Feasibility of factory calibration, i.e., sensor batch characterization in vitro with no further need for in vivo calibration, requires a predictable and stable in vivo sensor sensitivity and limited inter- and intra-subject variation of the ratio of interstitial to blood glucose concentration. Twelve volunteers wore two FreeStyle Navigator (Abbott Diabetes Care, Alameda, CA) continuous glucose monitoring systems for 5 days in parallel for two consecutive sensor wears (four sensors per subject, 48 sensors total). Sensors from a prototype sensor lot with a low variability in glucose sensitivity were used for the study. Median sensor sensitivity values based on capillary blood glucose were calculated per sensor and compared for inter- and intra-subject variation. Mean absolute relative difference (MARD) calculation and error grid analysis were performed using a single calibration factor for all sensors to simulate factory calibration and compared to standard fingerstick calibration. Sensor sensitivity variation in vitro was 4.6%, which increased to 8.3% in vivo (P < 0.0001). Analysis of variance revealed no significant inter-subject differences in sensor sensitivity (P = 0.134). Applying a single universal calibration factor retrospectively to all sensors resulted in a MARD of 10.4% and 88.1% of values in Clarke Error Grid Zone A, compared to a MARD of 10.9% and 86% of values in Error Grid Zone A for fingerstick calibration. Factory calibration of sensors for continuous subcutaneous glucose monitoring is feasible with similar accuracy to standard fingerstick calibration. Additional data are required to confirm this result in subjects with diabetes.

Formation Algorithms and Simulation Testbed

NASA Technical Reports Server (NTRS)

Wette, Matthew; Sohl, Garett; Scharf, Daniel; Benowitz, Edward

2004-01-01

Formation flying for spacecraft is a rapidly developing field that will enable a new era of space science. For one of its missions, the Terrestrial Planet Finder (TPF) project has selected a formation flying interferometer design to detect earth-like planets orbiting distant stars. In order to advance technology needed for the TPF formation flying interferometer, the TPF project has been developing a distributed real-time testbed to demonstrate end-to-end operation of formation flying with TPF-like functionality and precision. This is the Formation Algorithms and Simulation Testbed (FAST) . This FAST was conceived to bring out issues in timing, data fusion, inter-spacecraft communication, inter-spacecraft sensing and system-wide formation robustness. In this paper we describe the FAST and show results from a two-spacecraft formation scenario. The two-spacecraft simulation is the first time that precision end-to-end formation flying operation has been demonstrated in a distributed real-time simulation environment.

Evaluation of a Commercial Glycoprotein Enzyme-Linked Immunosorbent Assay for Measuring Vaccine Immunity to Varicella

PubMed Central

Kim, Yun Hwa; Hwang, Ji Young; Shim, Hye Min; Lee, Eunsil; Park, Songyong

2014-01-01

Purpose To evaluate a recently marketed commercial glycoprotein enzyme-linked immunosorbent assay (gpEIA) kit, the VaccZyme™ VZV gpEIA, for measuring the immunity of varicella-vaccinated children. Materials and Methods We investigated the accuracy and reproducibility of the VaccZyme™ VZV gpEIA kit for the detection of antibodies to VZV. We also examined the sensitivity, specificity, and correlation between antibody titers calculated with gpEIA versus fluorescent antibody to membrane antigen (FAMA) by using sera of 349 children, ranging from 1 to 6 years old. Results VaccZyme™ VZV gpEIA gave precise and reproducible intra- and inter-assay results. FAMA and gpEIA titers showed a linear correlation (Pearson correlation coefficient=0.987). The sensitivity and specificity of the VaccZyme™ gpEIA was 31.4% and 100%, respectively, when the guidelines of the gpEIA (<100 mIU/mL) and FAMA 1:4 were adopted as cutoff values. However, the maximum sensitivity and specificity were 88.9% and 95.1%, respectively, with the highest correlation (κ=0.840), if the cutoff values were set with gpEIA at 49.7 mIU/mL and FAMA 1:16. Conclusion These results demonstrate that the VaccZyme™ VZV gpEIA kit gave precise and reproducible data for measuring antibody titer after varicella vaccination. The results also showed that the antibody titer calculated with the VaccZyme™ gpEIA kit strongly correlated with the FAMA titer. However, cutoff values should be re-optimized for the evaluation of vaccine immunity. PMID:24532518

Hand-held dynamometry in patients with haematological malignancies: Measurement error in the clinical assessment of knee extension strength

PubMed Central

Knols, Ruud H; Aufdemkampe, Geert; de Bruin, Eling D; Uebelhart, Daniel; Aaronson, Neil K

2009-01-01

Background Hand-held dynamometry is a portable and inexpensive method to quantify muscle strength. To determine if muscle strength has changed, an examiner must know what part of the difference between a patient's pre-treatment and post-treatment measurements is attributable to real change, and what part is due to measurement error. This study aimed to determine the relative and absolute reliability of intra and inter-observer strength measurements with a hand-held dynamometer (HHD). Methods Two observers performed maximum voluntary peak torque measurements (MVPT) for isometric knee extension in 24 patients with haematological malignancies. For each patient, the measurements were carried out on the same day. The main outcome measures were the intraclass correlation coefficient (ICC ± 95%CI), the standard error of measurement (SEM), the smallest detectable difference (SDD), the relative values as % of the grand mean of the SEM and SDD, and the limits of agreement for the intra- and inter-observer '3 repetition average' and the 'highest value of 3 MVPT' knee extension strength measures. Results The intra-observer ICCs were 0.94 for the average of 3 MVPT (95%CI: 0.86–0.97) and 0.86 for the highest value of 3 MVPT (95%CI: 0.71–0.94). The ICCs for the inter-observer measurements were 0.89 for the average of 3 MVPT (95%CI: 0.75–0.95) and 0.77 for the highest value of 3 MVPT (95%CI: 0.54–0.90). The SEMs for the intra-observer measurements were 6.22 Nm (3.98% of the grand mean (GM) and 9.83 Nm (5.88% of GM). For the inter-observer measurements, the SEMs were 9.65 Nm (6.65% of GM) and 11.41 Nm (6.73% of GM). The SDDs for the generated parameters varied from 17.23 Nm (11.04% of GM) to 27.26 Nm (17.09% of GM) for intra-observer measurements, and 26.76 Nm (16.77% of GM) to 31.62 Nm (18.66% of GM) for inter-observer measurements, with similar results for the limits of agreement. Conclusion The results indicate that there is acceptable relative reliability for evaluating knee strength with a HHD, while the measurement error observed was modest. The HHD may be useful in detecting changes in knee extension strength at the individual patient level. PMID:19272149

Preparation of submicrometer monodispersed magnetic silica particles using a novel water in oil microemulsion: properties and application for enzyme immobilization.

PubMed

Tuttolomondo, Maria Victoria; Villanueva, Maria Emilia; Alvarez, Gisela Solange; Desimone, Martín Federico; Díaz, Luis Eduardo

2013-10-01

The synthesis of monodispersed magnetic silica nanoparticles (MSN) is described using a water-in-oil reverse microemulsion system that does not require the use of co-surfactants. Sodium silicate, Tween 20 as a neutral surfactant and 1-butanol as the organic phase were used. There are several advantages of the proposed method including a saturation magnetization value of 10 emu/g for the particles obtained, uniformity of size and that they are easily functionalized to bind urease covalently. Moreover, the intra-day, inter-day and long-term stability results confirm that the procedure was successful and the enzyme-linked MSNs were stable over repeated uses and storage retaining more than 75% activity after 4 months.

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

PubMed Central

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

2014-01-01

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

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

PubMed

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

2014-01-01

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

A validated HPLC-MS/MS assay for quantifying unstable pharmacologically active metabolites of clopidogrel in human plasma: application to a clinical pharmacokinetic study.

PubMed

Furlong, Michael T; Savant, Ishani; Yuan, Moucun; Scott, Laura; Mylott, William; Mariannino, Thomas; Kadiyala, Pathanjali; Roongta, Vikram; Arnold, Mark E

2013-05-01

Clopidogrel is prescribed for the treatment of Acute Coronary Syndrome and recent myocardial infarction, recent stroke, or established peripheral arterial disease. A sensitive and reliable high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) assay was developed and validated to enable reliable quantification of four diastereomeric and chemically reactive thiol metabolites, two of which are pharmacologically active, in human plasma. The metabolites were stabilized by alkylation of their reactive thiol moieties with 2-bromo-3'-methoxyacetophenone (MPB). Following organic solvent mediated-protein precipitation in a 96-well plate format, chromatographic separation was achieved by gradient elution on an Ascentis Express RP-amide column. Chromatographic conditions were optimized to ensure separation of the four derivatized active metabolites. Derivatized metabolites and stable isotope-labeled internal standards were detected by positive ion electrospray tandem mass spectrometry. The HPLC-MS/MS assay was validated over concentration ranges of 0.125-125 ng/mL for metabolites H1-H3 and 0.101-101 ng/mL for H4. Intra- and inter-assay precision values for replicate quality control samples were within 14.3% for all analytes during the assay validation. Mean quality control accuracy values were within ±6.3% of nominal values for all analytes. Assay recoveries were high (>79%). The four derivatized analytes were stable in human blood for at least 2 h at room temperature and on ice. The analytes were also stable in human plasma for at least 25 h at room temperature, 372 days at -20 °C and -70 °C, and following at least five freeze-thaw cycles. The validated assay was successfully applied to the quantification of all four thiol metabolites in human plasma in support of a human pharmacokinetic study. Copyright © 2013 Elsevier B.V. All rights reserved.

Assessment of waist-to-hip ratio attractiveness in women: an anthropometric analysis of digital silhouettes.

PubMed

Kościński, Krzysztof

2014-07-01

The low proportion of waist to hip size in females is a unique and adaptive human feature. In contemporary human populations, the waist-to-hip ratio (WHR) is negatively associated with women's health, fecundity, and cognitive ability. It is, therefore, hypothesized that men will prefer women with low WHR. Although this prediction is supported by many studies, considerable disagreement persists about which WHR values are the most attractive and the importance of WHR for attractiveness of the female body. Unfortunately, the methods applied thus far are flawed in several ways. In the present study, we investigated male preferences for female WHR using a high precision assessment procedure and digitally manufactured, high quality, anthropometrically informed stimuli which were disentangled from body mass covariation. Forty men were requested to choose the most attractive silhouette consecutively from six series (2 levels of realism × 3 levels of body mass), each consisting of 26 female images that varied in WHR (from .60 to .85 by .01). Substantial inter-individual variation in the choices made was observed. Nevertheless, low and average WHR values were chosen more frequently than above-average values or values below the normal variation of the trait. This preference pattern mirrors the relationship between WHR and mate value, suggesting that the preferences are adaptive.

Robustness of cluster synchronous patterns in small-world networks with inter-cluster co-competition balance

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

Zhang, Jianbao; Ma, Zhongjun, E-mail: mzj1234402@163.com; Chen, Guanrong

All edges in the classical Watts and Strogatz's small-world network model are unweighted and cooperative (positive). By introducing competitive (negative) inter-cluster edges and assigning edge weights to mimic more realistic networks, this paper develops a modified model which possesses co-competitive weighted couplings and cluster structures while maintaining the common small-world network properties of small average shortest path lengths and large clustering coefficients. Based on theoretical analysis, it is proved that the new model with inter-cluster co-competition balance has an important dynamical property of robust cluster synchronous pattern formation. More precisely, clusters will neither merge nor split regardless of adding ormore » deleting nodes and edges, under the condition of inter-cluster co-competition balance. Numerical simulations demonstrate the robustness of the model against the increase of the coupling strength and several topological variations.« less

Robustness of cluster synchronous patterns in small-world networks with inter-cluster co-competition balance

NASA Astrophysics Data System (ADS)

Zhang, Jianbao; Ma, Zhongjun; Chen, Guanrong

2014-06-01

All edges in the classical Watts and Strogatz's small-world network model are unweighted and cooperative (positive). By introducing competitive (negative) inter-cluster edges and assigning edge weights to mimic more realistic networks, this paper develops a modified model which possesses co-competitive weighted couplings and cluster structures while maintaining the common small-world network properties of small average shortest path lengths and large clustering coefficients. Based on theoretical analysis, it is proved that the new model with inter-cluster co-competition balance has an important dynamical property of robust cluster synchronous pattern formation. More precisely, clusters will neither merge nor split regardless of adding or deleting nodes and edges, under the condition of inter-cluster co-competition balance. Numerical simulations demonstrate the robustness of the model against the increase of the coupling strength and several topological variations.

Using Public Data for Comparative Proteome Analysis in Precision Medicine Programs.

PubMed

Hughes, Christopher S; Morin, Gregg B

2018-03-01

Maximizing the clinical utility of information obtained in longitudinal precision medicine programs would benefit from robust comparative analyses to known information to assess biological features of patient material toward identifying the underlying features driving their disease phenotype. Herein, the potential for utilizing publically deposited mass-spectrometry-based proteomics data to perform inter-study comparisons of cell-line or tumor-tissue materials is investigated. To investigate the robustness of comparison between MS-based proteomics studies carried out with different methodologies, deposited data representative of label-free (MS1) and isobaric tagging (MS2 and MS3 quantification) are utilized. In-depth quantitative proteomics data acquired from analysis of ovarian cancer cell lines revealed the robust recapitulation of observable gene expression dynamics between individual studies carried out using significantly different methodologies. The observed signatures enable robust inter-study clustering of cell line samples. In addition, the ability to classify and cluster tumor samples based on observed gene expression trends when using a single patient sample is established. With this analysis, relevant gene expression dynamics are obtained from a single patient tumor, in the context of a precision medicine analysis, by leveraging a large cohort of repository data as a comparator. Together, these data establish the potential for state-of-the-art MS-based proteomics data to serve as resources for robust comparative analyses in precision medicine applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hematological characteristics in neonates with twin anemia-polycythemia sequence (TAPS).

PubMed

Lopriore, E; Slaghekke, F; Oepkes, D; Middeldorp, J M; Vandenbussche, F P H A; Walther, F J

2010-03-01

To evaluate the neonatal hematological features of monochorionic twins with twin anemia-polycythemia sequence (TAPS) and to determine the additional diagnostic value of reticulocyte count measurement. A cohort of consecutive monochorionic twins with TAPS (n = 19) was included in the study and each twin pair was compared with two monochorionic twin pairs (n = 38) unaffected by TAPS or twin-twin transfusion syndrome (TTTS), matched for gestational age at birth. We measured full blood counts on day 1 and determined the incidence of anemia, polycythemia, reticulocytosis and thrombocytopenia. Median inter-twin hemoglobin (Hb) difference in monochorionic twins with and without TAPS was 13.7 g/dL and 2.4 g/dL, respectively (p < 0.01). Median inter-twin reticulocyte count ratio in twins with and without TAPS was 3.1 and 1.0, respectively (p < 0.01). Thrombocytopenia (platelet count < 150 x 10(9)/L) occurred more often in the TAPS group than in the control group, 45% (17/38) versus 11% (11/38), respectively (p < 0.01). In the TAPS group, mean platelet count was significantly lower in recipients than in donors, 133 x 10(9)/L versus 218 x 10(9)/L, respectively (p < 0.01). TAPS twins have a large inter-twin Hb difference in combination with a large inter-twin reticulocyte count ratio. Recipients are more often thrombocytopenic than donors, probably due to polycythemia. Copyright (c) 2010 John Wiley & Sons, Ltd.

A sensitive LC-MS/MS method for simultaneous determination of amygdalin and paeoniflorin in human plasma and its application.

PubMed

Li, Xiaobing; Shi, Fuguo; Gu, Pan; Liu, Lingye; He, Hua; Ding, Li

2014-04-01

A simple and sensitive HPLC-MS/MS method was developed and fully validated for the simultaneous determination of amygdalin (AD) and paeoniflorin (PF) in human plasma. For both analytes, the method exhibited high sensitivity (LLOQs of 0.6ng/mL) by selecting the ammonium adduct ions ([M+NH4](+)) as the precursor ions and good linearity over the concentration range of 0.6-2000ng/mL with the correlation coefficients>0.9972. The intra- and inter-day precision was lower than 10% in relation to relative standard deviation, while accuracy was within ±2.3% in terms of relative error for both analytes. The developed method was successfully applied to a pilot pharmacokinetic study of AD and PF in healthy volunteers after intravenous infusion administration of Huoxue-Tongluo lyophilized powder for injection. Copyright © 2014 Elsevier B.V. All rights reserved.

Quantification of rifampicin in human plasma and cerebrospinal fluid by a highly sensitive and rapid liquid chromatographic-tandem mass spectrometric method.

PubMed

Srivastava, Abhishek; Waterhouse, David; Ardrey, Alison; Ward, Stephen A

2012-11-01

A highly sensitive and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed to measure the levels of the antitubercular drug rifampicin (RIF) in human plasma and cerebrospinal fluid (CSF). The analyte and internal standard (IS) were isolated from plasma and CSF by a simple organic solvent based precipitation of proteins followed by centrifugation. Detection was carried out by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring (MRM) mode. The assay was linear in the concentration range 25-6400 ng/mL with intra- and inter-day precision of <7% and <8%, respectively. The validated method was applied to the study of RIF pharmacokinetics in human CSF and plasma over 25 h period after a 10 mg/kg oral dose. Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous determination of vancomycin and ceftazidime in cerebrospinal fluid in craniotomy patients by high-performance liquid chromatography.

PubMed

Ye, Guangming; Cai, Xuejian; Wang, Biao; Zhou, Zhongxian; Yu, Xiaohua; Wang, Weibin; Zhang, Jiandong; Wang, Yuhai; Dong, Jierong; Jiang, Yunyun

2008-11-04

A simple, accurate and rapid method for simultaneous analysis of vancomycin and ceftazidime in cerebrospinal fluid (CSF), utilizing high-performance liquid chromatography (HPLC), has been developed and thoroughly validated to satisfy strict FDA guidelines for bioanalytical methods. Protein precipitation was used as the sample pretreatment method. In order to increase the accuracy, tinidazole was chosen as the internal standard. Separation was achieved on a Diamonsil C18 column (200 mm x 4.6mm I.D., 5 microm) using a mobile phase composed of acetonitrile and acetate buffer (pH 3.5) (8:92, v/v) at room temperature (25 degrees C), and the detection wavelength was 240 nm. All the validation data, such as accuracy, precision, and inter-day repeatability, were within the required limits. The method was applied to determine vancomycin and ceftazidime concentrations in CSF in five craniotomy patients.

Sensitive high-performance liquid chromatography/mass spectrometry method for determination of steviol in rat plasma.

PubMed

Wang, L Z; Goh, B C; Fan, L; Lee, H S

2004-01-01

The main toxicological concern of stevioside, a highly potent sweetener from S. rebaudiana, is its main metabolite, steviol. To determine very low levels of steviol in in vivo experiments, a sensitive liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-MS) method was developed for quantifying steviol in rat plasma after oral administration of a single dose of stevioside (0.5 g/kg). The sample preparation uses liquid-liquid extraction with tert-butyl methyl ether in an acidic environment. The retention time of steviol was 10.5 min. The assay was linear over the range 2-1000 ng/mL with a lower limit of detection of 1 ng/mL. The intra- and inter-day precision were <5 and <7%, respectively, and the accuracy was in the range 95-108%. The steviol concentration profile in rat plasma was determined. Copyright 2003 John Wiley & Sons, Ltd.

Smart phone: a popular device supports amylase activity assay in fisheries research.

PubMed

Thongprajukaew, Karun; Choodum, Aree; Sa-E, Barunee; Hayee, Ummah

2014-11-15

Colourimetric determinations of amylase activity were developed based on a standard dinitrosalicylic acid (DNS) staining method, using maltose as the analyte. Intensities and absorbances of red, green and blue (RGB) were obtained with iPhone imaging and Adobe Photoshop image analysis. Correlation of green and analyte concentrations was highly significant, and the accuracy of the developed method was excellent in analytical performance. The common iPhone has sufficient imaging ability for accurate quantification of maltose concentrations. Detection limits, sensitivity and linearity were comparable to a spectrophotometric method, but provided better inter-day precision. In quantifying amylase specific activity from a commercial source (P>0.02) and fish samples (P>0.05), differences compared with spectrophotometric measurements were not significant. We have demonstrated that iPhone imaging with image analysis in Adobe Photoshop has potential for field and laboratory studies of amylase. Copyright © 2014 Elsevier Ltd. All rights reserved.

Simultaneous determination of the HIV nucleoside analogue reverse transcriptase inhibitors lamivudine, didanosine, stavudine, zidovudine and abacavir in human plasma by reversed phase high performance liquid chromatography.

PubMed

Verweij-van Wissen, C P W G M; Aarnoutse, R E; Burger, D M

2005-02-25

A reversed phase high performance liquid chromatography method was developed for the simultaneous quantitative determination of the nucleoside reverse transcriptase inhibitors (NRTIs) lamivudine, didanosine, stavudine, zidovudine and abacavir in plasma. The method involved solid-phase extraction with Oasis MAX cartridges from plasma, followed by high performance liquid chromatography with a SymmetryShield RP 18 column and ultraviolet detection set at a wavelength of 260 nm. The assay was validated over the concentration range of 0.015-5 mg/l for all five NRTIs. The average accuracies for the assay were 92-102%, inter- and intra-day coefficients of variation (CV) were <2.5% and extraction recoveries were higher than 97%. This method proved to be simple, accurate and precise, and is currently in use in our laboratory for the quantitative analysis of NRTIs in plasma.

Automated on-line SPE LC-MS/MS method to quantitate 6beta-hydroxycortisol and cortisol in human urine: use of the 6beta-hydroxycortisol to cortisol ratio as an indicator of CYP3A4 activity.

PubMed

Barrett, Yu Chen; Akinsanya, Billy; Chang, Shu-Ying; Vesterqvist, Ole

2005-07-25

A sensitive method for quantitation of urinary 6beta-hydroxycortisol (6beta-HC) and cortisol using on-line SPE and LC-MS/MS was developed and validated. Human urine samples were injected directly onto an on-line solid phase extraction apparatus, Prospekt-2, followed by HPLC separation and electrospray triple quadrupole LC-MS/MS detection. The inter-day precision for the 6beta-HC:cortisol ratio was 7-9%. The lower limit of quantitation was 1 and 0.2 ng/mL for 6beta-HC and cortisol, respectively. Using the method we observed a diurnal variation on the 6beta-HC:cortisol ratio in healthy volunteers with the maximal ratio observed in the 2-10 pm urine collection period.

High-performance liquid chromatographic assay for the determination of Aloe Emodin in mouse plasma.

PubMed

Zaffaroni, M; Mucignat, C; Pecere, T; Zagotto, G; Frapolli, R; D'Incalci, M; Zucchetti, M

2003-10-25

An isocratic high-performance liquid chromatography (HPLC) method was developed and validated to determine Aloe Emodin (AE) in mouse plasma. The analysis required 0.3 ml of plasma and involves extraction with dichloromethane. The HPLC separation was carried out on Symmetry Shield RP18, a mobile phase of methanol-water-acetic acid (65:35:0.2) and fluorescence detection at lambda(ex)=410 nm and lambda(em)=510 nm. The retention time of AE was 11.7 min. The assay was linear from 10 to 1,000 ng/ml (r2 > or = 0.999), showed intra- and inter-day precision within 7.8 and 4.7%, and accuracy of 87.3-105.7%. Detection limit (LOD) and quantification limit (LOQ) were 4.5 and 5 ng/ml, respectively. The method was applied to determine for the first time the pharmacokinetic of AE in mice.

Dispersive micro solid phase extraction (DMSPE) using polymer anion exchange (PAX) as the sorbent followed by UPLC-MS/MS for the rapid determination of four bisphenols in commercial edible oils.

PubMed

Xian, Yanping; Wu, Yuluan; Dong, Hao; Guo, Xindong; Wang, Bin; Wang, Li

2017-09-29

The present work presents a novel and rapid analytical method for the simultaneous analysis of bisphenol A (BPA), bisphenol B (BPB), bisphenol F (BPF) and bisphenol S (BPS) in edible oil based on dispersive micro solid phase extraction (DMSPE) for the first time followed by isotope dilution-ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The edible oil sample was dispersed by n-hexane and extracted with ammoniated methanol-water solution. Then the target analytes were dispersedly absorbed using the polymer anion exchange (PAX) as the sorbent and eluted by acidic methanol. After that, four bisphenols were separated on a C18 column by gradient elution with methanol and 0.05% ammonium hydroxide in water as mobile phase, detected by MS/MS under multiple reactions monitoring (MRM) mode and quantified by internal standard method. The PAX amounts, adsorption time, concentrations of formic acid in the elution solvent and volume of elution solvent for the DMSPE technique were optimized. The limit of detection and quantitation (LOD and LOQ), matrix effect, recovery and precision of the developed method were investigated. Results indicated that BPS and the rest three bisphenols displayed excellent linearity in the concentration ranges of 0.1-50μg/L and 0.5-250μg/L, respectively, with correlation coefficients (R 2 ) all larger than 0.998. Achieved MLODs (S/N=3) varied between 0.1-0.4μg/kg for all bisphenols. The mean recoveries at three spiked levels in edible oil were in the range of 87.3-108%. Intra-day precision (n=6) and inter-day precision (n=5) were <9% and <11%, respectively. This method is of rapid-and-simple pretreatment, accurate and sensitive, and suitable for the simultaneous determination of bisphenols in edible oil. Copyright © 2017. Published by Elsevier B.V.

Simultaneous extraction of polycyclic aromatic hydrocarbons through the complete dissolution of solid biological samples in sodium hydroxide/urea/thiourea aqueous solution.

PubMed

Mohammad, Sedigheh Ale; Ghanemi, Kamal; Larki, Arash

2016-12-09

In order to precisely and simultaneously extract polycyclic aromatic hydrocarbons (PAHs) for measurement using a high performance liquid chromatography-fluorescence detector (HPLC-FL), a novel sample preparation method was developed. This method is based on the complete and fast dissolution of biological samples in a new non-alcoholic alkaline medium. A solution composed of NaOH/urea/thiourea at an optimized ratio was used for complete dissolution of approximately 0.25g dried fish samples within 20min. The proposed method was conducted at 10°C and under atmospheric pressure to obtain a stable and highly homogeneous solution, without the need for microwaves or any other apparatus. This process operates at considerably lower temperature than conventional methods and provides an opportunity to simultaneously extract the target analytes from their matrices by adding the extracting solvent in the initial steps of the dissolution; this process greatly reduced the time of analysis and the loss of analytes via vaporization. Several key parameters were identified and their effects on precision and extraction recoveries were investigated. Linearity over a calibration range of 1.0-100 and 2.5-100ngg -1 was achieved, with high coefficients of determination (r 2 ) ranging between 0.9987 and 0.9998. Based on relative standard deviations (n=5), the intra-day and inter-day precisions of the spiked PAHs were found to be better than 3.1% and 3.2%, respectively, at a concentration level of 25ngg -1 . The recoveries of PAH from spiked marine fish tissues and shrimp samples were in the range of 90.6%-100.4%. The spiked samples were also treated with the alcoholic alkaline and Soxhlet extraction methods in order to provide a comparison. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

Zhang, Honggen; Wang, Zhenyu; Liu, Oscar

2016-02-01

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

Fluorescence, electrophoretic and chromatographic fingerprints of herbal medicines and their comparative chemometric analysis.

PubMed

Mazina, Jekaterina; Vaher, Merike; Kuhtinskaja, Maria; Poryvkina, Larisa; Kaljurand, Mihkel

2015-07-01

The aim of the present study was to compare the polyphenolic compositions of 47 medicinal herbs (HM) and four herbal tea mixtures from Central Estonia by rapid, reliable and sensitive Spectral Fluorescence Signature (SFS) method in a front face mode. The SFS method was validated for the main identified HM representatives including detection limits (0.037mgL(-1) for catechin, 0.052mgL(-1) for protocatechuic acid, 0.136mgL(-1) for chlorogenic acid, 0.058mgL(-1) for syringic acid and 0.256mgL(-1) for ferulic acid), linearity (up to 5.0-15mgL(-1)), intra-day precision (RSDs=6.6-10.6%), inter-day precision (RSDs=6.4-13.8%), matrix effect (-15.8 to +5.5) and recovery (85-107%). The phytochemical fingerprints were differentiated by parallel factor analysis (PARAFAC) combined with hierarchical cluster analysis (CA) and principal component analysis (PCA). HM were clustered into four main clusters (catechin-like, hydroxycinnamic acid-like, dihydrobenzoic acid-like derivatives containing HM and HM with low/very low content of fluorescent constituents) and 14 subclusters (rich, medium, low/very low contents). The average accuracy and precision of CA for validation HM set were 97.4% (within 85.2-100%) and 89.6%, (within 66.7-100%), respectively. PARAFAC-PCA/CA has improved the analysis of HM by the SFS method. The results were verified by two separation methods CE-DAD and HPLC-DAD-MS also combined with PARAFAC-PCA/CA. The SFS-PARAFAC-PCA/CA method has potential as a rapid and reliable tool for investigating the fingerprints and predicting the composition of HM or evaluating the quality and authenticity of different standardised formulas. Moreover, SFS-PARAFAC-PCA/CA can be implemented as a laboratory and/or an onsite method. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Validation of a rapid micellar electrokinetic capillary chromatographic method for the simultaneous determination of isoniazid and pyridoxine hydrochloride in pharmaceutical formulation.

PubMed

Nemutlu, E; Celebier, M; Uyar, B; Altinöz, S

2007-07-01

An efficient and reliable micellar electrokinetic capillary chromatography (MEKC) method has been developed for the simultaneous determination of isoniazid (ISO) and pyridoxine hydrochloride (PYR) in pharmaceutical formulations. A chemometric two level full factorial design approach was used to search for the optimum conditions of separation. Three parameters were selected for this study: the buffer pH, the buffer concentration and sodium dodecyl sulphate (SDS) concentrations. Resolution, peak symmetry and analysis time were established as response. The two analytes were separated within 6 min with the optimized conditions: 50 mM borate buffer, 25 mM SDS pH 7.8, 35 degrees C, at 50 mbar 4s injection and 30 kV by using a fused silica capillary (72 cm effective length, 50 microm i.d.). The detection wavelength was set to 205 nm. Meloxicam was used as internal standard. The method was validated with respect to stability, linearity range, limit of quantitation and detection, precision, accuracy, specificity and robustness. The detection limits of the method were 1.0 microg mL(-1) for ISO and 0.40 microg mL(-1) for PYR and the method was linear at least in the range of 3.0-100 microg mL(-1) for ISO and 1.0-100 microg mL(-1) for PYR with excellent correlation coefficients (0.9995 for ISO and 0.9998 for PYR). Relative standard deviations (R.S.D.s) of the described method ranged between 0.54 and 2.27% for intra-day precision and between 0.65 and 2.69% for inter-day precision. The developed method was applied to the tablet form of ISO and PYR-containing the pharmaceutical preparations and the data were compared with obtained from the standard addition method. No statistically significant difference was found.

[Precision medicine: new opportunities and challenges for molecular epidemiology].

PubMed

Song, Jing; Hu, Yonghua

2016-04-01

Since the completion of the Human Genome Project in 2003 and the announcement of the Precision Medicine Initiative by U.S. President Barack Obama in January 2015, human beings have initially completed the " three steps" of " genomics to biology, genomics to health as well as genomics to society". As a new inter-discipline, the emergence and development of precision medicine have relied on the support and promotion from biological science, basic medicine, clinical medicine, epidemiology, statistics, sociology and information science, etc. Meanwhile, molecular epidemiology is considered to be the core power to promote precision medical as a cross discipline of epidemiology and molecular biology. This article is based on the characteristics and research progress of medicine and molecular epidemiology respectively, focusing on the contribution and significance of molecular epidemiology to precision medicine, and exploring the possible opportunities and challenges in the future.

Simultaneous quantification of flavonoids and triterpenoids in licorice using HPLC.

PubMed

Wang, Yuan-Chuen; Yang, Yi-Shan

2007-05-01

Numerous bioactive compounds are present in licorice (Glycyrrhizae Radix), including flavonoids and triterpenoids. In this study, a reversed-phase high-performance liquid chromatography (HPLC) method for simultaneous quantification of three flavonoids (liquiritin, liquiritigenin and isoliquiritigenin) and four triterpenoids (glycyrrhizin, 18alpha-glycyrrhetinic acid, 18beta-glycyrrhetinic acid and 18beta-glycyrrhetinic acid methyl ester) from licorice was developed, and further, to quantify these 7 compounds from 20 different licorice samples. Specifically, the reverse-phase HPLC was performed with a gradient mobile phase composed of 25 mM phosphate buffer (pH 2.5)-acetonitrile featuring gradient elution steps as follows: 0 min, 100:0; 10 min, 80:20; 50 min, 70:30; 73 min, 50:50; 110 min, 50:50; 125 min, 20:80; 140 min, 20:80, and peaks were detected at 254 nm. By using our technique, a rather good specificity was obtained regarding to the separation of these seven compounds. The regression coefficient for the linear equations for the seven compounds lay between 0.9978 and 0.9992. The limits of detection and quantification lay in the range of 0.044-0.084 and 0.13-0.25 microg/ml, respectively. The relative recovery rates for the seven compounds lay between 96.63+/-2.43 and 103.55+/-2.77%. Coefficient variation for intra-day and inter-day precisions lay in the range of 0.20-1.84 and 0.28-1.86%, respectively. Based upon our validation results, this analytical technique is a convenient method to simultaneous quantify numerous bioactive compounds derived from licorice, featuring good quantification parameters, accuracy and precision.

Simultaneous quantification and identification of flavonoids, lignans, coumarin and amides in leaves of Zanthoxylum armatum using UPLC-DAD-ESI-QTOF-MS/MS.

PubMed

Bhatt, Vinod; Sharma, Sushila; Kumar, Neeraj; Sharma, Upendra; Singh, Bikram

2017-01-05

The current study presents isolation and characterization of twelve compounds including catechin (1), isovitexin (2), hesperidin (3), psoralin (4), eudesmin (5), kobusin (6), fargesin (7), sesamin (8), asarinin (9), planispine-A (10), α-sanshool (11) and vitexin (12), from the leaves of Zanthoxylum armatum. Further, two rapid and simple ultra performance liquid chromatography-diode array detection (UPLC-DAD) methods were developed for the simultaneous quantitative determination of isolated compounds from Z. armatum leaves. These analytical methods were validated for linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ). The LOD and LOQ were in the range of 0.06-0.21μg/mL and 0.19-0.69μg/mL, respectively. The validated method was linear (R 2 ≥0.9906), precise in terms of peak area (intra-day RSDs <3.8% and inter-day RSDs <2.7%), and accurate (109.6-92.5%). This is the first report on the isolation and quantification of 1, 2, 4 and 12 in Z. armatum and 3 in Zanthoxylum genus. The methods: were successfully applied to assess the quality of samples collected from different locations of Himachal Pradesh during summer and winter season. The results demonstrated that flavonoids and furofuran lignans were the major constituents in Z. armatum leaves. The developed methods: were further applied for tandem electrospray ionization-mass spectrometry (UPLC-DAD-ESI-MS/MS) and total eighteen compounds were identified including phenolic acid, flavonoids, furofuran lignans, coumarin and isobutyl amides. Copyright © 2016 Elsevier B.V. All rights reserved.

Simple determination of L-hydroxyproline in idiopathic pulmonary fibrosis lung tissues of rats using non-extractive high-performance liquid chromatography coupled with fluorescence detection after pre-column derivatization with novel synthetic 9-acetylimidazol-carbazole.

PubMed

Ren, Yan; Zhao, Juanjuan; Shi, Yanan; Chen, Caiyun; Chen, Xiangming; Lv, Changjun

2017-08-05

L-Hydroxyproline (L-Hyp) is an important biomarker for idiopathic pulmonary fibrosis (IPF). The quantitative methods based on high-performance liquid chromatography coupled with fluorescence detection after pre-column derivatization typically requires complicated derivatization conditions and obtains unstable derivatives. Here, a novel derivatization reagent, 9-acetylimidazol-carbazole, was synthesized for the first time to efficiently and rapidly label the amino groups of L-Hyp. The high-performance liquid chromatography method with pre-column derivatization was performed on an Agilent ZORBAX SB-C 18 column (4.6×250mm, 5μm). The product was measured using fluorescence detection at excitation and emission wavelengths of 232 and 370nm, respectively. The method was validated in specificity, linearity, limit of detection (66.7 fmol), limit of quantification (333.3fmol), intra-day precision (0.75%), inter-day precision (3.82%), stability (3.15%), and recovery (90.7-109.4%). The validated method was successfully applied to the determination of L-Hyp in the lung tissues of healthy and IPF rats. The results showed that the concentration of L-Hyp (3.64mg/g) in the IPF model was significantly higher than the concentration (2.33mg/g) in the healthy control group with P<0.01. This is a new method for the determination of L-Hyp and can be used for other amino acid-related studies in the future. Copyright © 2017. Published by Elsevier B.V.

Simultaneous determination of five major compounds in the traditional medicine Pyeongwee-San by high performance liquid chromatography-diode array detection and liquid chromatography-mass spectrometry/mass spectrometry.

PubMed

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

2014-01-01

Pyeongwee-San (PWS) has been widely used for treating acute gastritis, chronic, and gastritis. In this paper, simultaneous determination of five compounds (naringin, hesperidin, glycyrrhizin, atractylenolide III, and magnolol) from traditional medicine PWS using the high performance liquid chromatography (HPLC) was established for quality control. Optimum separations were obtained with a SHISEIDO C18 reverse-phase column by gradient elution with 0.1% Trifluoroacetic acid (TFA) water-acetonitrile as the mobile phase. The flow rate was 1 mL/min and detection wavelength was set at 205 nm and 250 nm. Validation of the analytical method was evaluated by linearity, precision, and accuracy test. The calibration curves were linear over the established range with R (2) > 0.9978. The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.09 to 0.43 and 0.27 to 1.29 μg/mL. The method exhibited intra-day and inter-day precision range between 0.01-1.86% and 0.04-0.35% respectively. The recoveries of five compounds in PWS were in the range between 93.18-106.40%, and 0.20-1.51%. The application of this method was identified through the successful analysis of five compounds in 12 batches of PWS. In addition, identification of five compounds was confirmed by a liquid chromatography method and mass spectrometry. The HPLC method was could be accomplished to the quality control and stable experiment for the preparations consisted of five major compounds.

Measurement of HbA1c in Gingival Crevicular Blood Using a High Pressure Liquid Chromatography Procedure

PubMed Central

Pesce, Michael A.; Strauss, Shiela M.; Rosedale, Mary; Netterwald, Jane; Wang, Hangli

2016-01-01

Objectives To validate an ion exchange high-pressure liquid chromatography (HPLC) method for measuring glycated hemoglobin (HbA1c) in gingival crevicular blood (GCB) spotted on filter paper, for use in screening dental patients for diabetes. Methods We collected the GCB specimens for this study from the oral cavities of patients during dental visits, using rigorous strategies to obtain GCB that was as free of debris as possible. The analytical performance of the HPLC method was determined by measuring the precision, linearity, carryover, stability of HbA1c in GCB, and correlation of HbA1c results in GCB specimens with finger-stick blood (FSB) specimens spotted on filter paper. Results The coefficients of variation (CVs) for the inter- and intrarun precision of the method were less than 2.0%. Linearity ranged between 4.2% and 12.4%; carryover was less than 2.0%, and the stability of the specimen was 6 days at 4°C and as many as 14 days at −70°C. Linear regression analysis comparing the HbA1c results in GCB with FSB yielded a correlation coefficient of 0.993, a slope of 0.981, and an intercept of 0.13. The Bland-Altman plot showed no difference in the HbA1c results from the GCB and FSB specimens at normal, prediabetes, and diabetes HbA1c levels. Conclusion We validated an HPLC method for measuring HbA1c in GCB; this method can be used to screen dental patients for diabetes. PMID:26489673

Inter-Annual and Shorter-Term Variability in Physical and Biological Characteristics Across Barrow Canyon in August - September 2005-2014

NASA Astrophysics Data System (ADS)

Ashjian, C. J.; Okkonen, S. R.; Campbell, R. G.; Alatalo, P.

2014-12-01

Late summer physical and biological conditions along a 37-km transect crossing Barrow Canyon have been described for the past ten years as part of an ongoing program, supported by multiple funding sources including the NSF AON, focusing on inter-annual variability and the formation of a bowhead whale feeding hotspot near Barrow. These repeated transects (at least two per year, separated in time by days-weeks) provide an opportunity to assess the inter-annual and shorter term (days-weeks) changes in hydrographic structure, ocean temperature, current velocity and transport, chlorophyll fluorescence, nutrients, and micro- and mesozooplankton community composition and abundance. Inter-annual variability in all properties was high and was associated with larger scale, meteorological forcing. Shorter-term variability could also be high but was strongly influenced by changes in local wind forcing. The sustained sampling at this location provided critical measures of inter-annual variability that should permit detection of longer-term trends that are associated with ongoing climate change.

Comparison of the quantification of acetaminophen in plasma, cerebrospinal fluid and dried blood spots using high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Taylor, Rachel R; Hoffman, Keith L; Schniedewind, Björn; Clavijo, Claudia; Galinkin, Jeffrey L; Christians, Uwe

2013-09-01

Acetaminophen (paracetamol, N-(4-hydroxyphenyl) acetamide) is one of the most commonly prescribed drugs for the management of pain in children. Quantification of acetaminophen in pre-term and term neonates and small children requires the availability of highly sensitive assays in small volume blood samples. We developed and validated an LC-MS/MS assay for the quantification of acetaminophen in human plasma, cerebro-spinal fluid (CSF) and dried blood spots (DBS). Reconstitution in water (DBS only) and addition of a protein precipitation solution containing the deuterated internal standard were the only manual steps. Extracted samples were analyzed on a Kinetex 2.6 μm PFP column using an acetonitrile/formic acid gradient. The analytes were detected in the positive multiple reaction mode. Alternatively, DBS were automatically processed using direct desorption in a sample card and preparation (SCAP) robotic autosampler in combination with online extraction. The range of reliable response in plasma and CSF was 3.05-20,000 ng/ml (r(2)>0.99) and 27.4-20,000 ng/ml (r(2)>0.99) for DBS (manual extraction and automated direct desorption). Inter-day accuracy was always within 85-115% and inter-day precision for plasma, CSF and manually extracted DBS were less than 15%. Deming regression analysis comparing 167 matching pairs of plasma and DBS samples showed a correlation coefficient of 0.98. Bland Altman analysis indicated a 26.6% positive bias in DBS, most likely reflecting the blood: plasma distribution ratio of acetaminophen. DBS are a valid matrix for acetaminophen pharmacokinetic studies. Copyright © 2013 Elsevier B.V. All rights reserved.

Development and validation of a hydrophilic interaction liquid chromatography-tandem mass spectrometry method for the quantification of lipid-related extracellular metabolites in Saccharomyces cerevisiae.

PubMed

Sun, Tao; Wetzel, Stephanie J; Johnson, Mitchell E; Surlow, Beth A; Patton-Vogt, Jana

2012-05-15

A highly sensitive hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method was developed and validated for the quantification of glycerophosphoinositol (GroPIns), glycerophosphocholine (GroPCho), glycerol 3-phosphate (GroP), inositol, and choline in the extracellular medium of Saccharomyces cerevisiae. The media samples were pretreated with a single two-phase liquid extraction. Chromatographic separation was achieved on a Waters Xbridge HILIC (150 mm × 4.6 mm, 5 μm) column under isocratic conditions using a mobile phase composed of acetonitrile/water, 70:30 (v/v) with 10mM ammonium acetate (pH adjusted to 4.5) at a flow-rate of 0.5 mL/min. Using a triple quadrupole tandem mass spectrometer, samples were detected in multiple reaction monitoring (MRM) mode via an electrospray ionization (ESI) source. The calibration curves were linear (r² ≥ 0.995) over the range of 0.5-150 nM, with the lower limit of quantitation validated at 0.5 nM for all analytes. The intra- and inter-day precision (calculated by coefficient of variation, CV%) ranged from 1.24 to 5.88% and 2.46 to 9.77%, respectively, and intra- and inter-day accuracy (calculated by relative error, RE%) was between -8.42 to 8.22% and -9.35 to 6.62%, respectively, at all quality control levels. The extracellular metabolites were stable throughout various storage stability studies. The fully validated method was successfully applied to determine the extracellular levels of phospholipid-related metabolites in S. cerevisiae. Copyright © 2012 Elsevier B.V. All rights reserved.

UPLC-MS/MS assay of riluzole in human plasma and cerebrospinal fluid (CSF): Application in samples from spinal cord injured patients.

PubMed

Sarkar, Mahua; Grossman, Robert G; Toups, Elizabeth G; Chow, Diana S-L

2017-11-30

In the present study, a sensitive and robust LC-MS/MS method has been developed and validated for the quantification of riluzole in human plasma and cerebrospinal fluid (CSF) in clinical samples from patients with spinal cord injury (SCI). Riluzole and its labeled internal standard (IS) were isolated from plasma and CSF by liquid-liquid extraction using ethyl acetate. Riluzole (m/z 235→166) and IS (m/z 238→169) were detected by electrospray ionization (ESI) using multiple reaction monitoring (MRM) in a positive mode. The assay was linear in the concentration range of 0.5 (LLOQ, signal/noise ratio>10)-800ng/ml in plasma, and 1.0 (LLOQ)-800ng/ml in CSF samples. The intra- and inter-day accuracy in plasma were 94.2-110.0% and 97.8-102.0%, respectively, and those in CSF were 87.6-105.1% and 91.9-98.8%, respectively. The intra- and inter-day precision were 2.2-7.2% and 4.0-9.1%, respectively, in plasma, and 1.4-14.1% and 2.6-11.5%, respectively in CSF. Matrix effect was negligible from both matrices with signal percentages of 97.6-100.6% in plasma and 99.4-106.4% in CSF. The recoveries were >75% in plasma, >84% in CSF with low protein (53.9mg/dl), and >68% in CSF with high protein (348.2mg/dl). This method was successfully applied to quantify riluzole concentrations in plasma and CSF from patients with SCI. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantitative determination of opioids in whole blood using fully automated dried blood spot desorption coupled to on-line SPE-LC-MS/MS.

PubMed

Verplaetse, Ruth; Henion, Jack

2016-01-01

Opioids are well known, widely used painkillers. Increased stability of opioids in the dried blood spot (DBS) matrix compared to blood/plasma has been described. Other benefits provided by DBS techniques include point-of-care collection, less invasive micro sampling, more economical shipment, and convenient storage. Current methodology for analysis of micro whole blood samples for opioids is limited to the classical DBS workflow, including tedious manual punching of the DBS cards followed by extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS) bioanalysis. The goal of this study was to develop and validate a fully automated on-line sample preparation procedure for the analysis of DBS micro samples relevant to the detection of opioids in finger prick blood. To this end, automated flow-through elution of DBS cards was followed by on-line solid-phase extraction (SPE) and analysis by LC-MS/MS. Selective, sensitive, accurate, and reproducible quantitation of five representative opioids in human blood at sub-therapeutic, therapeutic, and toxic levels was achieved. The range of reliable response (R(2)  ≥0.997) was 1 to 500 ng/mL whole blood for morphine, codeine, oxycodone, hydrocodone; and 0.1 to 50 ng/mL for fentanyl. Inter-day, intra-day, and matrix inter-lot accuracy and precision was less than 15% (even at lower limits of quantitation (LLOQ) level). The method was successfully used to measure hydrocodone and its major metabolite norhydrocodone in incurred human samples. Our data support the enormous potential of DBS sampling and automated analysis for monitoring opioids as well as other pharmaceuticals in both anti-doping and pain management regimens. Copyright © 2015 John Wiley & Sons, Ltd.

Simultaneous Quantification of Free Cholesterol, Cholesteryl Esters, and Triglycerides without Ester Hydrolysis by UHPLC Separation and In-Source Collision Induced Dissociation Coupled MS/MS

NASA Astrophysics Data System (ADS)

Gardner, Michael S.; McWilliams, Lisa G.; Jones, Jeffrey I.; Kuklenyik, Zsuzsanna; Pirkle, James L.; Barr, John R.

2017-08-01

We demonstrate the application of in-source nitrogen collision-induced dissociation (CID) that eliminates the need for ester hydrolysis before simultaneous analysis of esterified cholesterol (EC) and triglycerides (TG) along with free cholesterol (FC) from human serum, using normal phase liquid chromatography (LC) coupled to atmospheric pressure chemical ionization (APCI) tandem mass spectrometry (MS/MS). The analysis requires only 50 μL of 1:100 dilute serum with a high-throughput, precipitation/evaporation/extraction protocol in one pot. Known representative mixtures of EC and TG species were used as calibrators with stable isotope labeled analogs as internal standards. The APCI MS source was operated with nitrogen source gas. Reproducible in-source CID was achieved with the use of optimal cone voltage (declustering potential), generating FC, EC, and TG lipid class-specific precursor fragment ions for multiple reaction monitoring (MRM). Using a representative mixture of purified FC, CE, and TG species as calibrators, the method accuracy was assessed with analysis of five inter-laboratory standardization materials, showing -10% bias for Total-C and -3% for Total-TG. Repeated duplicate analysis of a quality control pool showed intra-day and inter-day variation of 5% and 5.8% for FC, 5.2% and 8.5% for Total-C, and 4.1% and 7.7% for Total-TG. The applicability of the method was demonstrated on 32 serum samples and corresponding lipoprotein sub-fractions collected from normolipidemic, hypercholesterolemic, hypertriglyceridemic, and hyperlipidemic donors. The results show that in-source CID coupled with isotope dilution UHPLC-MS/MS is a viable high precision approach for translational research studies where samples are substantially diluted or the amounts of archived samples are limited. [Figure not available: see fulltext.

Wearable Vector Electrical Bioimpedance System to Assess Knee Joint Health

PubMed Central

Hersek, Sinan; Töreyin, Hakan; Teague, Caitlin N.; Millard-Stafford, Mindy L.; Jeong, Hyeon-Ki; Bavare, Miheer M.; Wolkoff, Paul; Sawka, Michael N.; Inan, Omer T.

2017-01-01

Objective We designed and validated a portable electrical bioimpedance (EBI) system to quantify knee joint health. Methods Five separate experiments were performed to demonstrate the: (1) ability of the EBI system to assess knee injury and recovery; (2) inter-day variability of knee EBI measurements; (3) sensitivity of the system to small changes in interstitial fluid volume; (4) reducing the error of EBI measurements using acceleration signals; (5) use of the system with dry electrodes integrated to a wearable knee wrap. Results (1) The absolute difference in resistance (R) and reactance (X) from the left to the right knee was able to distinguish injured and healthy knees (p<0.05); the absolute difference in R decreased significantly (p<0.05) in injured subjects following rehabilitation. (2) The average inter-day variability (standard deviation) of the absolute difference in knee R was 2.5Ω, and for X was, 1.2 Ω. (3) Local heating/cooling resulted in a significant decrease/increase in knee R (p<0.01). (4) The proposed subject position detection algorithm achieved 97.4% leave-one subject out cross-validated accuracy and 98.2% precision in detecting when the subject is in the correct position to take measurements. (5) Linear regression between the knee R and X measured using the wet electrodes and the designed wearable knee wrap were highly correlated (r2 = 0.8 and 0.9, respectively). Conclusion This work demonstrates the use of wearable EBI measurements in monitoring knee joint health. Significance The proposed wearable system has the potential for assessing knee joint health outside the clinic/lab and help guide rehabilitation. PMID:28026745

Capillary electrophoresis determination of glucosamine in nutraceutical formulations after labeling with anthranilic acid and UV detection.

PubMed

Volpi, Nicola

2009-04-05

A new robust CE method for the determination of the glucosamine (GlcN) content in nutraceutical formulations is described after its derivatization with anthranilic acid (2-aminobenzoic acid, AA). The CE separation of derivatized GlcN with AA was performed on an uncoated fused-silica capillary tube (50 microm I.D.) using an operating pH 7.0 buffer of 150 mM boric acid/50 mM NaH2PO4 and UV detection at 214 nm. The method was validated for specificity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). The detector response for GlcN was linear over the selected concentration range from 240 to 2400 pg (40-400 microg/mL) with a correlation coefficient greater than 0.980. The intra- and inter-day variations (CV%) were between 0.5 and 0.9 for migration time, and between 2.8 and 4.3 for peak area, respectively. The LOD and the LOQ of the method were approximately 200 and 500 pg, respectively. The intra- and inter-day accuracy was estimated to range from 2.8% to 5.1%, while the percent recoveries of GlcN in formulations were calculated to be about 100% after simple centrifugation for 10 min, lyophilization and derivatization with AA. The CE method was applied to the determination of GlcN content, in the form of GlcN-hydrochloride or GlcN-sulfate, of several nutraceutical preparations in the presence of other ingredients, i.e. chondroitin sulfate, vitamin C and/or methylsulfonylmethane (MSM) as well as salts and other agents. The quantitative results obtained were in total conformity with the label claims.

Simple and quick determination of analgesics and other contaminants of emerging concern in environmental waters by on-line solid phase extraction coupled to liquid chromatography-tandem mass spectrometry.

PubMed

Ferrer-Aguirre, Alejandra; Romero-González, Roberto; Vidal, J L Martínez; Frenich, Antonia Garrido

2016-05-13

A simple and quick analytical method has been developed for the determination of pharmaceutical compounds in water. An on-line solid-phase extraction (SPE) coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been optimized to determine 7 contaminants of emerging concern in environmental waters at ngL(-1) levels. This procedure requires minimal sample handling and small sample volume (900μL) with a total running time of 18min. Several SPE parameters were evaluated and optimized in order to achieve a high sample throughput. Therefore sample volume, carryover and reusability of the cartridges were evaluated. Performance characteristics were evaluated and good linearity was obtained (R(2)>0.98). Recoveries were evaluated in spiked samples at three concentrations and the values ranged from 71 to 104%. Intra and inter-day precision was lower than 10 and 13% respectively. Limits of quantification were equal to or lower than 10ngL(-1), except for 1,7-dimethylxanthine (20ngL(-1)) and ibuprofen (50ngL(-1)). The method was applied to 20 environmental water samples, and ibuprofen was the compound most widely detected at concentrations up to 42.06μgL(-1), whereas the other compounds were detected in fewer samples at lower concentrations (up to 15.99μgL(-1)). Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of metoserpate, buquinolate, and diclofenac in pork, eggs, and milk using liquid chromatography-tandem mass spectrometry.

PubMed

Park, Jin-A; Abd El-Aty, A M; Zheng, Weijia; Kim, Seong-Kwan; Choi, Jeong-Min; Hacımüftüoğlu, Ahmet; Shim, Jae-Han; Shin, Ho-Chul

2018-06-01

In this work, a method was developed for the simultaneous determination of residual metoserpate, buquinolate and diclofenac in pork, milk, and eggs. Samples were extracted with 0.1% formic acid in acetonitrile, defatted with n-hexane, and filtered prior to analysis using liquid chromatography-tandem mass spectrometry. The analytes were separated on a C 18 column using 0.1% acetic acid and methanol as the mobile phase. The matrix-matched calibration curves showed good linearity over a concentration range of 5-50 ng/g with coefficients of determination (R 2 ) ≥0.991. The intra- and inter-day accuracies (expressed as recovery percentage values) calculated using three spiking levels (5, 10, and 20 μg/kg) were 80-108.65 and 74.06-107.15%, respectively, and the precisions (expressed as relative standard deviation) were 2.86-13.67 and 0.05-11.74%, respectively, for the tested drugs determined in various matrices. The limits of quantification (1 and 2 μg/kg) were below the uniform residual level (0.01 mg/kg) set for compounds that have no specific maximum residue limit (MRL). The developed method was tested using market samples and none of the target analytes was detected in any of the samples. The validated method proved to be practicable for detection of the tested analytes in pork, milk, and eggs. Copyright © 2018 John Wiley & Sons, Ltd.

Simultaneous Determination of Decursin, Decursinol Angelate, Nodakenin, and Decursinol of Angelica gigas Nakai in Human Plasma by UHPLC-MS/MS: Application to Pharmacokinetic Study.

PubMed

Kim, Sook-Jin; Ko, Se-Mi; Choi, Eun-Jeong; Ham, Seong-Ho; Kwon, Young-Dal; Lee, Yong-Bok; Cho, Hea-Young

2018-04-26

Coumarins in Cham-dang-gwi, the dried root of Angelica gigas Nakai (AGN), possess pharmacological effects on anemia, pain, infection, and articular rheumatism. The AGN root containes decursin (D), decursinol angelate (DA), nodakenin, and decursinol (DOH), a major metabolite of D and DA. The aim of this study was to develop a simultaneous determination method for these four coumarins in human plasma using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Chromatographic separation was performed on dual columns (Kinetex ® C 18 column and Capcell core C 18 column) with mobile phase consisting of water and acetonitrile at a flow rate of 0.3 mL/min using gradient elution. Multiple reaction monitoring was operated in positive ion mode with precursors to product ion transition values of m / z 328.9→228.8, 328.9→228.9, 409.4→248.8, and 246.8→212.9 to measure D, DA, nodakenin, and DOH, respectively. Linear calibration curves were fitted over concentration range of 0.05⁻50 ng/mL for these four components, with correlation coefficient greater than 0.995. Inter- and intra-day accuracies were between 90.60% and 108.24%. These precisions were within 11.19% for all components. The established method was then applied to a pharmacokinetic study for the four coumarins after usual dosing in Korean subjects.

Novel atomic absorption spectrometric and rapid spectrophotometric methods for the quantitation of paracetamol in saliva: application to pharmacokinetic studies.

PubMed

Issa, M M; Nejem, R M; El-Abadla, N S; Al-Kholy, M; Saleh, Akila A

2008-01-01

A novel atomic absorption spectrometric method and two highly sensitive spectrophotometric methods were developed for the determination of paracetamol. These techniques based on the oxidation of paracetamol by iron (III) (method I); oxidation of p-aminophenol after the hydrolysis of paracetamol (method II). Iron (II) then reacts with potassium ferricyanide to form Prussian blue color with a maximum absorbance at 700 nm. The atomic absorption method was accomplished by extracting the excess iron (III) in method II and aspirates the aqueous layer into air-acetylene flame to measure the absorbance of iron (II) at 302.1 nm. The reactions have been spectrometrically evaluated to attain optimum experimental conditions. Linear responses were exhibited over the ranges 1.0-10, 0.2-2.0 and 0.1-1.0 mug/ml for method I, method II and atomic absorption spectrometric method, respectively. A high sensitivity is recorded for the proposed methods I and II and atomic absorption spectrometric method value indicate: 0.05, 0.022 and 0.012 mug/ml, respectively. The limit of quantitation of paracetamol by method II and atomic absorption spectrometric method were 0.20 and 0.10 mug/ml. Method II and the atomic absorption spectrometric method were applied to demonstrate a pharmacokinetic study by means of salivary samples in normal volunteers who received 1.0 g paracetamol. Intra and inter-day precision did not exceed 6.9%.

A Rapid LC-HRMS Method for the Determination of Domoic Acid in Urine Using a Self-Assembly Pipette Tip Solid-Phase Extraction

PubMed Central

Zhang, Yiping; Chen, Dawei; Hong, Zhuan

2015-01-01

In this study, we developed a self-assembly pipette tip solid-phase extraction (PTSPE) method using a high molecular weight polymer material (PAX) as the adsorbent for the determination of domoic acid (DA) in human urine samples by liquid chromatography high-resolution mass spectrometry (LC-HRMS) analysis. The PTSPE cartridge, assembled by packing 9.1 mg of PAX as sorbent into a 200 μL pipette tip, showed high adsorption capacity for DA owing to the strong cationic properties of PAX. Compared with conventional SPE, the PTSPE is simple and fast, and shows some advantages in the aspects of less solvent consumption, low cost, the absence of the evaporation step, and short time requirement. All the parameters influencing the extraction efficiency such as pH, the amount of sorbent, the number of aspirating/dispensing cycles, and the type and volume of eluent in PTSPE were carefully investigated and optimized. Under the optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) values of DA were 0.12 μg/L and 0.37 μg/L respectively. The extraction recoveries of DA from the urine samples spiked at four different concentrations were in a range from 88.4% to 102.5%. The intra- and inter-day precisions varied from 2.1% to 7.6% and from 2.6% to 12.7%, respectively. The accuracy ranged from −1.9% to −7.4%. PMID:26729165

Stir bar sorptive extraction and liquid chromatography-tandem mass spectrometry determination of polar and non-polar emerging and priority pollutants in environmental waters.

PubMed

Aparicio, Irene; Martín, Julia; Santos, Juan Luis; Malvar, José Luis; Alonso, Esteban

2017-06-02

An analytical method based on stir bar sorptive extraction (SBSE) was developed and validated for the determination of environmental concern pollutants in environmental waters by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Target compounds include six water and oil repellents (perfluorinated compounds), four preservatives (butylated hydroxytoluene and three parabens), two plasticizers (bisphenol A and di(2-ethylhexyl)phthalate), seven surfactants (four linear alkylbenzene sulfonates, nonylphenol and two nonylphenol ethoxylates), a flame retardant (hexabromocyclododecane), four hormones, fourteen pharmaceutical compounds, an UV-filter (2-ethylhexyl 4-methoxycinnamate) and nine pesticides. To achieve the simultaneous extraction of polar and non-polar pollutants two stir bar coatings were tested, the classic polydimethylsiloxane (PDMS) coating and the novel ethylene glycol modified silicone (EG-silicone). The best extraction recoveries were obtained using EG-silicone coating. The effects of sample pH, volume and ionic strength and extraction time on extraction recoveries were evaluated. The analytical method was validated for surface water and tap water samples. The method quantification limits ranged from 7.0ngL -1 to 177ngL -1 . The inter-day precision, expressed as relative standard deviation, was lower than 20%. Accuracy, expressed as relative recovery values, was in the range from 61 to 130%. The method was applied for the determination of the 48 target compounds in surface and tap water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed Central

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

2017-01-01

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

Novel Atomic Absorption Spectrometric and Rapid Spectrophotometric Methods for the Quantitation of Paracetamol in Saliva: Application to Pharmacokinetic Studies

PubMed Central

Issa, M. M.; Nejem, R. M.; El-Abadla, N. S.; Al-Kholy, M.; Saleh, Akila. A.

2008-01-01

A novel atomic absorption spectrometric method and two highly sensitive spectrophotometric methods were developed for the determination of paracetamol. These techniques based on the oxidation of paracetamol by iron (III) (method I); oxidation of p-aminophenol after the hydrolysis of paracetamol (method II). Iron (II) then reacts with potassium ferricyanide to form Prussian blue color with a maximum absorbance at 700 nm. The atomic absorption method was accomplished by extracting the excess iron (III) in method II and aspirates the aqueous layer into air-acetylene flame to measure the absorbance of iron (II) at 302.1 nm. The reactions have been spectrometrically evaluated to attain optimum experimental conditions. Linear responses were exhibited over the ranges 1.0-10, 0.2-2.0 and 0.1-1.0 μg/ml for method I, method II and atomic absorption spectrometric method, respectively. A high sensitivity is recorded for the proposed methods I and II and atomic absorption spectrometric method value indicate: 0.05, 0.022 and 0.012 μg/ml, respectively. The limit of quantitation of paracetamol by method II and atomic absorption spectrometric method were 0.20 and 0.10 μg/ml. Method II and the atomic absorption spectrometric method were applied to demonstrate a pharmacokinetic study by means of salivary samples in normal volunteers who received 1.0 g paracetamol. Intra and inter-day precision did not exceed 6.9%. PMID:20046743

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

PubMed

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

2009-02-20

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

Urinalysis: The Automated Versus Manual Techniques; Is It Time To Change?.

PubMed

Ahmed, Asmaa Ismail; Baz, Heba; Lotfy, Sarah

2016-01-01

Urinalysis is the third major test in clinical laboratory. Manual technique imprecision urges the need for a rapid reliable automated test. We evaluated the H800-FUSIOO automatic urine sediment analyzer and compared it to the manual urinalysis technique to determine if it may be a competitive substitute in laboratories of central hospitals. 1000 urine samples were examined by the two methods in parallel. Agreement, precision, carryover, drift, sensitivity, specificity, and practicability criteria were tested. Agreement ranged from excellent to good for all urine semi-quantitative components (K > 0.4, p = 0.000), except for granular casts (K = 0.317, p = 0.000). Specific gravity results correlated well between the two methods (r = 0.884, p = 0.000). RBCS and WBCs showed moderate correlation (r = 0.42, p = 0.000) and (r = 0.44, p = 0.000), respectively. The auto-analyzer's within-run precision was > 75% for all semi-quantitative components except for proteins (50% precision). This finding in addition to the granular casts poor agreement indicate the necessity of operator interference at the critical cutoff values. As regards quantitative contents, RBCs showed a mean of 69.8 +/- 3.95, C.V. = 5.7, WBCs showed a mean of 38.9 +/- 1.9, C.V. = 4.9). Specific gravity, pH, microalbumin, and creatinine also showed good precision results with C.Vs of 0.000, 2.6, 9.1, and 0.00 respectively. In the between run precision, positive control showed good precision (C.V. = 2.9), while negative control's C.V. was strikingly high (C.V. = 127). Carryover and drift studies were satisfactory. Manual examination of inter-observer results showed major discrepancies (< 60% similar readings), while intra-observer's results correlated well with each other (r = 0.99, p = 0.000). Automation of urinalysis decreases observer-associated variation and offers prompt competitive results when standardized for screening away from the borderline cutoffs.

Introduction to Precision Guided Munitions, A Handbook Providing Tutorial Information and Data on Precision Guided Munitions (PGM). Volume 1. Tutorial. Revision

DTIC Science & Technology

1983-05-01

serve as inter- faces to provide a compatible hook-up. Recent advances in microprocessors are leaoing to the development of new techniques known as...killed. This sort of threat is new to warfare. Because of the lack of experience against such a threat, effective tactics have not been developed ...Recent developments have been on satellite-to-earth communications links, antijam capabilities, adaptive array antennas, and new equipment to exploit the

Anamolous ionospheric TEC variations prior to the Indonesian earthquake (M 7.1) of November 15, 2014

NASA Astrophysics Data System (ADS)

Alcay, Salih

2017-05-01

This paper investigates preearthquake ionospheric variations with the use of TEC of Global Ionospheric Maps (GIMs) and regional maps based on Precise Point Positioning (PPP) during the 7.1-M Indonesian earthquake that occurred on November 15, 2014. TEC maps corresponding to 10 days before to 4 days after the event were examined. In addition, a time series of TEC values according to the PPP maps were also evaluated. In addition to GIMs, it was possible to detect TEC variations with PPP maps. The results showed that ionospheric TEC decreased strikingly 4 days prior to the earthquake. This TEC variation was highly likely related to seismic activity.

Locally induced neuronal synchrony precisely propagates to specific cortical areas without rhythm distortion.

PubMed

Toda, Haruo; Kawasaki, Keisuke; Sato, Sho; Horie, Masao; Nakahara, Kiyoshi; Bepari, Asim K; Sawahata, Hirohito; Suzuki, Takafumi; Okado, Haruo; Takebayashi, Hirohide; Hasegawa, Isao

2018-05-16

Propagation of oscillatory spike firing activity at specific frequencies plays an important role in distributed cortical networks. However, there is limited evidence for how such frequency-specific signals are induced or how the signal spectra of the propagating signals are modulated during across-layer (radial) and inter-areal (tangential) neuronal interactions. To directly evaluate the direction specificity of spectral changes in a spiking cortical network, we selectively photostimulated infragranular excitatory neurons in the rat primary visual cortex (V1) at a supra-threshold level with various frequencies, and recorded local field potentials (LFPs) at the infragranular stimulation site, the cortical surface site immediately above the stimulation site in V1, and cortical surface sites outside V1. We found a significant reduction of LFP powers during radial propagation, especially at high-frequency stimulation conditions. Moreover, low-gamma-band dominant rhythms were transiently induced during radial propagation. Contrastingly, inter-areal LFP propagation, directed to specific cortical sites, accompanied no significant signal reduction nor gamma-band power induction. We propose an anisotropic mechanism for signal processing in the spiking cortical network, in which the neuronal rhythms are locally induced/modulated along the radial direction, and then propagate without distortion via intrinsic horizontal connections for spatiotemporally precise, inter-areal communication.

Direct MSTID mitigation in precise GPS processing

NASA Astrophysics Data System (ADS)

Hernández-Pajares, Manuel; Wielgosz, Pawel; Paziewski, Jacek; Krypiak-Gregorczyk, Anna; Krukowska, Marta; Stepniak, Katarzyna; Kaplon, Jan; Hadas, Tomasz; Sosnica, Krzysztof; Bosy, Jaroslaw; Orus-Perez, Raul; Monte-Moreno, Enric; Yang, Heng; Garcia-Rigo, Alberto; Olivares-Pulido, Germán.

2017-03-01

In this paper, the authors summarize a simple and efficient approach developed to mitigate the problem in precise Global Navigation Satellite Systems (GNSS) positioning originated by the most frequent ionospheric wave signatures: the medium-scale traveling ionospheric disturbances (MSTIDs). The direct GNSS Ionospheric Interferometry technique (hereinafter dGII), presented in this paper, is applied for correcting MSTID effects on precise Real Time Kinematic (RTK) and tropospheric determination. It consists of the evolution of the former climatic Differential Delay Mitigation Model for MSTIDs (DMTID), for real-time conditions, using ionospheric data from a single permanent receiver only. The performance is demonstrated with networks of GNSS receivers in Poland, treated as users under real-time conditions, during two representative days in winter and summer seasons (days 353 and 168 of year 2013). In range domain, dGII typically reduces the ionospheric delay error up to 10-90% of the value when the MSTID mitigation model is not applied. The main dGII impact on precise positioning is that we can obtain reliable RTK position faster. In particular, the ambiguity success rate parameter increases, from 74% to 83%, with respect to the original uncorrected observations. The average of time to first fix is shortened from 30 s to 13 s. The improvement in troposphere estimaton, due to any potential impact of the MSTID mitigation model, was most difficult to demonstrate.

Computational Calorimetry: High-Precision Calculation of Host–Guest Binding Thermodynamics

PubMed Central

2015-01-01

We present a strategy for carrying out high-precision calculations of binding free energy and binding enthalpy values from molecular dynamics simulations with explicit solvent. The approach is used to calculate the thermodynamic profiles for binding of nine small molecule guests to either the cucurbit[7]uril (CB7) or β-cyclodextrin (βCD) host. For these systems, calculations using commodity hardware can yield binding free energy and binding enthalpy values with a precision of ∼0.5 kcal/mol (95% CI) in a matter of days. Crucially, the self-consistency of the approach is established by calculating the binding enthalpy directly, via end point potential energy calculations, and indirectly, via the temperature dependence of the binding free energy, i.e., by the van’t Hoff equation. Excellent agreement between the direct and van’t Hoff methods is demonstrated for both host–guest systems and an ion-pair model system for which particularly well-converged results are attainable. Additionally, we find that hydrogen mass repartitioning allows marked acceleration of the calculations with no discernible cost in precision or accuracy. Finally, we provide guidance for accurately assessing numerical uncertainty of the results in settings where complex correlations in the time series can pose challenges to statistical analysis. The routine nature and high precision of these binding calculations opens the possibility of including measured binding thermodynamics as target data in force field optimization so that simulations may be used to reliably interpret experimental data and guide molecular design. PMID:26523125

Rapid determination of benzodiazepines, zolpidem and their metabolites in urine using direct injection liquid chromatography-tandem mass spectrometry.

PubMed

Jeong, Yu-Dong; Kim, Min Kyung; Suh, Sung Ill; In, Moon Kyo; Kim, Jin Young; Paeng, Ki-Jung

2015-12-01

Benzodiazepines and zolpidem are generally prescribed as sedative, hypnotics, anxiolytics or anticonvulsants. These drugs, however, are frequently misused in drug-facilitated crime. Therefore, a rapid and simple liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for identification and quantification of benzodiazepines, zolpidem and their metabolites in urine using deuterium labeled internal standards (IS). Urine samples (120 μL) mixed with 80 μL of the IS solution were centrifuged. An aliquot (5 μL) of the sample solution was directly injected into the LC-MS/MS system for analysis. The mobile phases consisted of water and acetonitrile containing 2mM ammonium trifluoroacetate and 0.2% acetic acid. The analytical column was a Zorbax SB-C18 (100 mm × 2.1 mm i.d., 3.5 μm, Agilent). The separation and detection of 18 analytes were achieved within 10 min. Calibration curves were linear over the concentration ranges of 0.5-20 ng/mL (zolpidem), 1.0-40 ng/mL (flurazepam and temazepam), 2.5-100 ng/mL (7-aminoclonazepam, 1-hydroxymidazolam, midazolam, flunitrazepam and alprazolam), 5.0-200 ng/mL (zolpidem phenyl-4-carboxylic acid, α-hydroxyalprazolam, oxazepam, nordiazepam, triazolam, diazepam and α-hydroxytriazolam), 10-400 ng/mL (lorazepam and desalkylflurazepam) and 10-100 ng/mL (N-desmethylflunitrazepam) with the coefficients of determination (r(2)) above 0.9971. The dilution integrity of the analytes was examined for supplementation of short linear range. Dilution precision and accuracy were tested using two, four and ten-folds dilutions and they ranged from 3.7 to 14.4% and -12.8 to 12.5%, respectively. The process efficiency for this method was 63.0-104.6%. Intra- and inter-day precisions were less than 11.8% and 9.1%, while intra- and inter-day accuracies were less than -10.0 to 8.2%, respectively. The lower limits of quantification were lower than 10 ng/mL for each analyte. The applicability of the developed method was successfully verified with human urine samples from drug users (n=21). Direct urine sample injection and optimized mobile phases were introduced for simple sample preparation and high-sensitivity with the desired separation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Method for automatic determination of soybean actual evapotranspiration under open top chambers (OTC) subjected to effects of water stress and air ozone concentration.

PubMed

Rana, Gianfranco; Katerji, Nader; Mastrorilli, Marcello

2012-10-01

The present study describes an operational method, based on the Katerji et al. (Eur J Agron 33:218-230, 2010) model, for determining the daily evapotranspiration (ET) for soybean inside open top chambers (OTCs). It includes two functions, calculated day par day, making it possible to separately take into account the effects of concentrations of air ozone and plant water stress. This last function was calibrated in function of the daily values of actual water reserve in the soil. The input variables of the method are (a) the diurnal values of global radiation and temperature, usually measured routinely in a standard weather station; (b) the daily values of the AOT40 index accumulated (accumulated ozone over a threshold of 40 ppb during daylight hours, when global radiation exceeds 50 Wm(-2)) determined inside the OTC; and (c) the actual water reserve in the soil, at the beginning of the trial. The ensemble of these input variables can be automatable; thus, the proposed method could be applied in routine. The ability of the method to take into account contrasting conditions of ozone air concentration and water stress was evaluated over three successive years, for 513 days, in ten crop growth cycles, excluding the days employed to calibrate the method. Tests were carried out in several chambers for each year and take into account the intra- and inter-year variability of ET measured inside the OTCs. On the daily scale, the slope of the linear regression between the ET measured by the soil water balance and that calculated by the proposed method, under different water conditions, are 0.98 and 1.05 for the filtered and unfiltered (or enriched) OTCs with root mean square error (RMSE) equal to 0.77 and 1.07 mm, respectively. On the seasonal scale, the mean difference between measured and calculated ET is equal to +5% and +11% for the filtered and unfiltered OTCs, respectively. The ability of the proposed method to estimate the daily and seasonal ET inside the OTCs is therefore satisfactory following inter- and intra-annual tests. Finally, suggestions about the applications of the proposed method for other species, different from soybean, were also discussed.

Clinical indicators for routine use in the evaluation of early psychosis intervention: development, training support and inter-rater reliability.

PubMed

Catts, Stanley V; Frost, Aaron D J; O'Toole, Brian I; Carr, Vaughan J; Lewin, Terry; Neil, Amanda L; Harris, Meredith G; Evans, Russell W; Crissman, Belinda R; Eadie, Kathy

2011-01-01

Clinical practice improvement carried out in a quality assurance framework relies on routinely collected data using clinical indicators. Herein we describe the development, minimum training requirements, and inter-rater agreement of indicators that were used in an Australian multi-site evaluation of the effectiveness of early psychosis (EP) teams. Surveys of clinician opinion and face-to-face consensus-building meetings were used to select and conceptually define indicators. Operationalization of definitions was achieved by iterative refinement until clinicians could be quickly trained to code indicators reliably. Calculation of percentage agreement with expert consensus coding was based on ratings of paper-based clinical vignettes embedded in a 2-h clinician training package. Consensually agreed upon conceptual definitions for seven clinical indicators judged most relevant to evaluating EP teams were operationalized for ease-of-training. Brief training enabled typical clinicians to code indicators with acceptable percentage agreement (60% to 86%). For indicators of suicide risk, psychosocial function, and family functioning this level of agreement was only possible with less precise 'broad range' expert consensus scores. Estimated kappa values indicated fair to good inter-rater reliability (kappa > 0.65). Inspection of contingency tables (coding category by health service) and modal scores across services suggested consistent, unbiased coding across services. Clinicians are able to agree upon what information is essential to routinely evaluate clinical practice. Simple indicators of this information can be designed and coding rules can be reliably applied to written vignettes after brief training. The real world feasibility of the indicators remains to be tested in field trials.

High performance liquid chromatographic assay for the quantitation of total glutathione in plasma

NASA Technical Reports Server (NTRS)

Abukhalaf, Imad K.; Silvestrov, Natalia A.; Menter, Julian M.; von Deutsch, Daniel A.; Bayorh, Mohamed A.; Socci, Robin R.; Ganafa, Agaba A.

2002-01-01

A simple and widely used homocysteine HPLC procedure was applied for the HPLC identification and quantitation of glutathione in plasma. The method, which utilizes SBDF as a derivatizing agent utilizes only 50 microl of sample volume. Linear quantitative response curve was generated for glutathione over a concentration range of 0.3125-62.50 micromol/l. Linear regression analysis of the standard curve exhibited correlation coefficient of 0.999. Limit of detection (LOD) and limit of quantitation (LOQ) values were 5.0 and 15 pmol, respectively. Glutathione recovery using this method was nearly complete (above 96%). Intra-assay and inter-assay precision studies reflected a high level of reliability and reproducibility of the method. The applicability of the method for the quantitation of glutathione was demonstrated successfully using human and rat plasma samples.

Simultaneous quantification of coumarins, flavonoids and limonoids in Fructus Citri Sarcodactylis by high performance liquid chromatography coupled with diode array detector.

PubMed

Chu, Jun; Li, Song-Lin; Yin, Zhi-Qi; Ye, Wen-Cai; Zhang, Qing-Wen

2012-07-01

A high performance liquid chromatography coupled with diode array detector (HPLC-DAD) method was developed for simultaneous quantification of eleven major bioactive components including six coumarins, three flavonoids and two limonoids in Fructus Citri Sarcodactylis. The analysis was performed on a Cosmosil 5 C(18)-MS-II column (4.6 mm × 250 mm, 5 μm) with water-acetonitrile gradient elution. The method was validated in terms of linearity, sensitivity, precision, stability and accuracy. It was found that the calibration curves for all analytes showed good linearity (R(2)>0.9993) within the test ranges. The overall limit of detection (LOD) and limit of quantification (LOQ) were less than 3.0 and 10.2 ng. The relative standard deviations (RSDs) for intra- and inter-day repeatability were not more than 4.99% and 4.92%, respectively. The sample was stable for at least 48 h. The spike recoveries of eleven components were 95.1-104.9%. The established method was successfully applied to determine eleven components in three samples from different locations. The results showed that the newly developed HPLC-DAD method was linear, sensitive, precise and accurate, and could be used for quality control of Fructus Citri Sarcodactylis. Copyright © 2012 Elsevier B.V. All rights reserved.

A quantitative determination of fluorochloridone in rat plasma by UPLC-MS/MS method: application to a pharmacokinetic study.

PubMed

Liu, Shihong; Shi, Jingmin; Fan, Junpei; Sun, Jie; Zhang, Suhui; Hu, Yue; Wei, Li; Wu, Chunhua; Chang, Xiuli; Tang, Liming; Zhou, Zhijun

2016-08-01

A precise, high-throughput and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed for the determination of fluorochloridone (FLC) in rat plasma. The extraction of analytes from plasma samples was carried out by protein precipitation procedure using acetonitrile prior to UPLC-MS/MS analysis. Verapamil was proved as a proper internal standard (IS) among many candidates. The chromatographic separation based on UPLC was well optimized. Multiple reaction monitoring in positive electrospray ionization was used with the optimized MS transitions at: m/z 312.0 → 292.0 for FLC and m/z 456.4 → 165.2 for IS. This method was well validated with good linear response (r(2)  > 0.998) observed over the investigated range of 3-3000 ng/mL and with satisfactory stability. This method was also characterized with adequate intra- and inter-day precision and accuracy (within 12%) in the quality control samples, and with high selectivity and less matrix effect observed. Total running time was only 1.5 min. This method has been successfully applied to a pilot FLC pharmacokinetic study after oral administration. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

A sensitive and rapid determination of ranitidine in human plasma by HPLC with fluorescence detection and its application for a pharmacokinetic study.

PubMed

Ulu, Sevgi Tatar; Tuncel, Muzaffer

2012-04-01

A novel precolumn derivatization reversed-phase high-performance liquid chromatography method with fluorescence detection is described for the determination of ranitidine in human plasma. The method was based on the reaction of ranitidine with 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole forming yellow colored fluorescent product. The separation was achieved on a C(18) column using methanol-water (60:40, v/v) mobile phase. Fluorescence detection was used at the excitation and emission of 458 and 521 nm, respectively. Lisinopril was utilized as an internal standard. The flow rate was 1.2 mL/min. Ranitidine and lisinopril appeared at 3.24 and 2.25 min, respectively. The method was validated for system suitability, precision, accuracy, linearity, limit of detection, limit of quantification, recovery and robustness. Intra- and inter-day precisions of the assays were in the range of 0.01-0.44%. The assay was linear over the concentration range of 50-2000 ng/mL. The mean recovery was determined to be 96.40 ± 0.02%. This method was successfully applied to a pharmacokinetic study after oral administration of a dose (150 mg) of ranitidine. © The Author [2012]. Published by Oxford University Press. All rights reserved.

A Concept for Airborne Precision Spacing for Dependent Parallel Approaches

NASA Technical Reports Server (NTRS)

Barmore, Bryan E.; Baxley, Brian T.; Abbott, Terence S.; Capron, William R.; Smith, Colin L.; Shay, Richard F.; Hubbs, Clay

2012-01-01

The Airborne Precision Spacing concept of operations has been previously developed to support the precise delivery of aircraft landing successively on the same runway. The high-precision and consistent delivery of inter-aircraft spacing allows for increased runway throughput and the use of energy-efficient arrivals routes such as Continuous Descent Arrivals and Optimized Profile Descents. This paper describes an extension to the Airborne Precision Spacing concept to enable dependent parallel approach operations where the spacing aircraft must manage their in-trail spacing from a leading aircraft on approach to the same runway and spacing from an aircraft on approach to a parallel runway. Functionality for supporting automation is discussed as well as procedures for pilots and controllers. An analysis is performed to identify the required information and a new ADS-B report is proposed to support these information needs. Finally, several scenarios are described in detail.

A new method for measuring lung deposition efficiency of airborne nanoparticles in a single breath

NASA Astrophysics Data System (ADS)

Jakobsson, Jonas K. F.; Hedlund, Johan; Kumlin, John; Wollmer, Per; Löndahl, Jakob

2016-11-01

Assessment of respiratory tract deposition of nanoparticles is a key link to understanding their health impacts. An instrument was developed to measure respiratory tract deposition of nanoparticles in a single breath. Monodisperse nanoparticles are generated, inhaled and sampled from a determined volumetric lung depth after a controlled residence time in the lung. The instrument was characterized for sensitivity to inter-subject variability, particle size (22, 50, 75 and 100 nm) and breath-holding time (3-20 s) in a group of seven healthy subjects. The measured particle recovery had an inter-subject variability 26-50 times larger than the measurement uncertainty and the results for various particle sizes and breath-holding times were in accordance with the theory for Brownian diffusion and values calculated from the Multiple-Path Particle Dosimetry model. The recovery was found to be determined by residence time and particle size, while respiratory flow-rate had minor importance in the studied range 1-10 L/s. The instrument will be used to investigate deposition of nanoparticles in patients with respiratory disease. The fast and precise measurement allows for both diagnostic applications, where the disease may be identified based on particle recovery, and for studies with controlled delivery of aerosol-based nanomedicine to specific regions of the lungs.

Development of the lunar gravity field model GrazLGM300b in the framework of project GRAZIL

NASA Astrophysics Data System (ADS)

Krauss, Sandro; Klinger, Beate; Wirnsberger, Harald; Baur, Oliver; Mayer-Gürr, Torsten

2015-04-01

The objective of project GRAZIL is to compile a high-accurate gravity field model of the Moon based on measurements provided by the Gravity Recovery And Interior Laboratory (GRAIL) mission. In order to reach this goal we perform dynamic precise orbit determination from radio science observations (Doppler range-rates) in combination with the analysis of inter-satellite ranging observations. We present an updated version of the lunar gravity field models GrazLGM200a (Klinger et al. 2014; doi: 10.1016/j.pss.2013.12.001) and GrazLGM300a (prepared for the 2014 AGU Fall Meeting) derived from inter-satellite Ka-band ranging (KBR) observations collected by GRAIL during the primary mission phase (March 1 to May 29, 2012). We exploit the KBR data by an integral equation approach using short orbital arcs. The basic idea behind this technique is to reformulate Newton's equation of motion as a boundary value problem. In this contribution particular attention is paid to processing details associated with the error structure of the observations and the incorporation of non-gravitational accelerations (with emphasis on solar radiation pressure, lunar albedo and self-shadowing). We validate our results against recent GRAIL models computed at NASA-GSFC and NASA-JPL.

Selective molecularly imprinted polymer combined with restricted access material for in-tube SPME/UHPLC-MS/MS of parabens in breast milk samples.

PubMed

Souza, Israel D; Melo, Lidervan P; Jardim, Isabel C S F; Monteiro, Juliana C S; Nakano, Ana Marcia S; Queiroz, Maria Eugênia C

2016-08-17

A new molecularly imprinted polymer modified with restricted access material (a hydrophilic external layer), (MIP-RAM) was synthesized via polymerization in situ in an open fused silica capillary. This stationary phase was used as sorbent for in-tube solid phase microextraction (in-tube SPME) to determine parabens in breast milk samples by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Scanning electron micrographs (SEM) illustrate MIP surface modification after glycerol dimethacrylate (hydrophilic monomer) incorporation. The interaction between parabens and MIP-RAM was investigated by Fourier-transform infrared (FTIR) spectroscopy. The Scatchard plot for MIP-RAM presented two linear parts with different slopes, illustrating binding sites with high- and low-affinity. Endogenous compounds exclusion from the MIP-RAM capillary was demonstrated by in-tube SPME/LC-UV assays carried out with blank milk samples. The in-tube SPME/UHPLC-MS/MS method presented linear range from 10 ng mL(-1) (LLOQ) to 400 ng mL(-1) with coefficients of determination higher than 0.99, inter-assay precision with coefficient of variation (CV) values ranging from 2 to 15%, and inter-assay accuracy with relative standard deviation (RSD) values ranging from -1% to 19%. Analytical validation parameters attested that in-tube SPME/UHPLC-MS/MS is an appropriate method to determine parabens in human milk samples to assess human exposure to these compounds. Analysis of breast milk samples from lactating women demonstrated that the proposed method is effective. Copyright © 2016 Elsevier B.V. All rights reserved.

GPS satellite clock determination in case of inter-frequency clock biases for triple-frequency precise point positioning

NASA Astrophysics Data System (ADS)

Guo, Jiang; Geng, Jianghui

2017-12-01

Significant time-varying inter-frequency clock biases (IFCBs) within GPS observations prevent the application of the legacy L1/L2 ionosphere-free clock products on L5 signals. Conventional approaches overcoming this problem are to estimate L1/L5 ionosphere-free clocks in addition to their L1/L2 counterparts or to compute IFCBs between the L1/L2 and L1/L5 clocks which are later modeled through a harmonic analysis. In contrast, we start from the undifferenced uncombined GNSS model and propose an alternative approach where a second satellite clock parameter dedicated to the L5 signals is estimated along with the legacy L1/L2 clock. In this manner, we do not need to rely on the correlated L1/L2 and L1/L5 ionosphere-free observables which complicates triple-frequency GPS stochastic models, or account for the unfavorable time-varying hardware biases in undifferenced GPS functional models since they can be absorbed by the L5 clocks. An extra advantage over the ionosphere-free model is that external ionosphere constraints can potentially be introduced to improve PPP. With 27 days of triple-frequency GPS data from globally distributed stations, we find that the RMS of the positioning differences between our GPS model and all conventional models is below 1 mm for all east, north and up components, demonstrating the effectiveness of our model in addressing triple-frequency observations and time-varying IFCBs. Moreover, we can combine the L1/L2 and L5 clocks derived from our model to calculate precisely the L1/L5 clocks which in practice only depart from their legacy counterparts by less than 0.006 ns in RMS. Our triple-frequency GPS model proves convenient and efficient in combating time-varying IFCBs and can be generalized to more than three frequency signals for satellite clock determination.

Design and Development of a Quantitative TaqMan Real-Time PCR Assay for Evaluation of HIV-1 (group M) Viral Load in Plasma Using Armored RNA Standard.

PubMed

Gholami, Mohammad; Baesi, Kazem; Rouzbahani, Negin H; Mohraz, Minoo

2018-06-01

Human immunodeficiency virus-1 (HIV-1) is a viral infectious agent that gradually extinguishes the immune system, resulting in the acquired immune deficiency syndrome (AIDS). The aim of this study was to develop a TaqMan based detection assay to evaluate HIV-1 plasma viral load and to construct a stable internal positive control (IPC) and external positive control (EPC) RNA based on Armored RNA (AR) technology. The MS2 maturase, coat protein gene and HIV-1 pol gene were cloned in pET-32a plasmid. The recently fabricated recombinant plasmid was transformed into Escherichia coli strain BL2 (DE3) and protein expression and Armored RNA was fabricated in presence of isopropyl-L-thio-D-galactopyranoside (IPTG). The Armored RNA was precipitated and purified by polyethylene glycol (PEG) and sephacryl S-200 chromatography. The stability of Armored RNA was evaluated by treatment with DNase I and RNase A and confirmed by transmission electron microscopy (TEM) and gel agarose electrophoresis. The specificity, sensitivity, inter- and intra-day precision, and the dynamic range of the assay were experimentally determined. The AR was stable in presence of ribonuclease, and the assay had a dynamic detection range from 101 to 105 copies of AR. The coefficient of variation (CV) was 4.8% for intra-assay and 5.8% for inter-assay precision. Clinical specificity and sensitivity of the assay were assessed at 100% and 96.66%, respectively. The linear regression analysis confirmed a high correlation between the in-house and the commercial assay, Real Star HIV-1-qRTPCR, respectively (R2 = 0.888). The AR standard is non-infectious and highly resistant in the presence of ribonuclease. The TaqMan assay developed is able to quantify HIV viral load based on a novel conserved region of HIV-1 pol gene which has minimal sequence inconsistency.

Measurement of the setting expansion of phosphate-bonded investment materials: Part I - Development of the Casting-Ring Test.

PubMed

Lloyd, C H; Yearn, J A; Cowper, G A; Blavier, J; Vanderdonckt, M

2004-07-01

The setting expansion is an important property for a phosphate-bonded investment material. This research was undertaken to investigate a test that might be suitable for its measurement when used in a Standard. In the 'Casting-Ring Test', the investment sample is contained in a steel ring and expands to displace a precisely positioned pin. Variables with the potential to alter routine reproduction of the value were investigated. The vacuum-mixer model is a production laboratory variable that must not be ignored and for this reason, experiments were repeated using a different vacuum-mixer located at a second test site. Restraint by the rigid ring material increased expansion, while force on the pin reduced it. Expansion was specific to the lining selected. Increased environmental temperature decreased the final value. Expansion was still taking place at a time at which its value might be measured. However, when these factors are set, the reproducibility of values for setting expansion was good at both test sites (coefficient of variation 14%, at most). The results revealed that with the control that is available reliable routine measurement is possible in a Standard test. The inter-laboratory variable, vacuum-mixer model, produced significant differences and it should be the subject of further investigation.

Geomagnetic field and length-of-day fluctuations at decadal and subdecadal time scales. A plea for looking beyond the atmosphere for partners in Earth's rotation

NASA Astrophysics Data System (ADS)

Demetrescu, C.; Dobrica, V.; Stefan, C.

2017-12-01

A rich scientific literature is linking length-of-day (LOD) fluctuations to geomagnetic field and flow oscillations in the fluid outer core. We demostrate that the temporal evolution of the geomagnetic field shows the existence of several oscillations at decadal, inter-decadal, and sub-centennial time scales that superimpose on a so-called inter-centennial constituent. We show that while the subcentennial oscillations of the geomagnetic field, produced by torsional oscillations in the core, could be linked to oscillations of LOD at a similar time scale, the oscillations at decadal and sub-decadal time scales, of external origin, can be found in LOD too. We discuss these issues from the perspective of long time-span main field models (gufm1 - Jackson et al., 2000; COV-OBS - Gillet et al., 2013) that are used to retrieve time series of geomagnetic elements in a 2.5x2.5° network. The decadal and sub-decadal constituents of the time series of annual values in LOD and geomagnetic field were separated in the cyclic component of a Hodrick-Prescott filtering applied to data, and shown to highly correlate to variations of external sources such as the magnetospheric ring current.

Modelling personality, plasticity and predictability in shelter dogs

PubMed Central

2017-01-01

Behavioural assessments of shelter dogs (Canis lupus familiaris) typically comprise standardized test batteries conducted at one time point, but test batteries have shown inconsistent predictive validity. Longitudinal behavioural assessments offer an alternative. We modelled longitudinal observational data on shelter dog behaviour using the framework of behavioural reaction norms, partitioning variance into personality (i.e. inter-individual differences in behaviour), plasticity (i.e. inter-individual differences in average behaviour) and predictability (i.e. individual differences in residual intra-individual variation). We analysed data on interactions of 3263 dogs (n = 19 281) with unfamiliar people during their first month after arrival at the shelter. Accounting for personality, plasticity (linear and quadratic trends) and predictability improved the predictive accuracy of the analyses compared to models quantifying personality and/or plasticity only. While dogs were, on average, highly sociable with unfamiliar people and sociability increased over days since arrival, group averages were unrepresentative of all dogs and predictions made at the individual level entailed considerable uncertainty. Effects of demographic variables (e.g. age) on personality, plasticity and predictability were observed. Behavioural repeatability was higher one week after arrival compared to arrival day. Our results highlight the value of longitudinal assessments on shelter dogs and identify measures that could improve the predictive validity of behavioural assessments in shelters. PMID:28989764

Accuracy and precision of polyurethane dental arch models fabricated using a three-dimensional subtractive rapid prototyping method with an intraoral scanning technique.

PubMed

Kim, Jae-Hong; Kim, Ki-Baek; Kim, Woong-Chul; Kim, Ji-Hwan; Kim, Hae-Young

2014-03-01

This study aimed to evaluate the accuracy and precision of polyurethane (PUT) dental arch models fabricated using a three-dimensional (3D) subtractive rapid prototyping (RP) method with an intraoral scanning technique by comparing linear measurements obtained from PUT models and conventional plaster models. Ten plaster models were duplicated using a selected standard master model and conventional impression, and 10 PUT models were duplicated using the 3D subtractive RP technique with an oral scanner. Six linear measurements were evaluated in terms of x, y, and z-axes using a non-contact white light scanner. Accuracy was assessed using mean differences between two measurements, and precision was examined using four quantitative methods and the Bland-Altman graphical method. Repeatability was evaluated in terms of intra-examiner variability, and reproducibility was assessed in terms of inter-examiner and inter-method variability. The mean difference between plaster models and PUT models ranged from 0.07 mm to 0.33 mm. Relative measurement errors ranged from 2.2% to 7.6% and intraclass correlation coefficients ranged from 0.93 to 0.96, when comparing plaster models and PUT models. The Bland-Altman plot showed good agreement. The accuracy and precision of PUT dental models for evaluating the performance of oral scanner and subtractive RP technology was acceptable. Because of the recent improvements in block material and computerized numeric control milling machines, the subtractive RP method may be a good choice for dental arch models.

Highly sensitive spectrofluorimetric determination of lomefloxacin in spiked human plasma, urine and pharmaceutical preparations.

PubMed

Ulu, Sevgi Tatar

2009-09-01

A sensitive, simple and selective spectrofluorimetric method was developed for the determination of lomefloxacin in biological fluids and pharmaceutical preparations. The method is based on the reaction between the drug and 4-chloro-7-nitrobenzodioxazole in borate buffer of pH 8.5 to yield a highly fluorescent derivative that is measured at 533 nm after excitation at 433 nm. The calibration curves were linear over the concentration ranges of 12.5-625, 15-1500 and 20-2000 ng/mL for plasma, urine and standard solution, respectively. The limits of detection were 4.0 ng/mL in plasma, 5.0 ng/mL in urine and 7.0 ng/mL in standard solution. The intra-assay accuracy and precision in plasma ranged from 0.032 to 2.40% and 0.23 to 0.36%, respectively, while inter-assay accuracy and precision ranged from 0.45 to 2.10% and 0.25 to 0.38%, respectively. The intra-assay accuracy and precision estimated on spiked samples in urine ranged from 1.27 to 4.20% and 0.12 to 0.24%, respectively, while inter-assay accuracy and precision ranged from 1.60 to 4.00% and 0.14 to 0.25%, respectively. The mean recovery of lomefloxacin from plasma and urine was 98.34 and 98.43%, respectively. The method was successfully applied to the determination of lomefloxacin in pharmaceuticals and biological fluids.

Validation of a standardized mapping system of the hip joint for radial MRA sequencing.

PubMed

Klenke, Frank M; Hoffmann, Daniel B; Cross, Brian J; Siebenrock, Klaus A

2015-03-01

Intraarticular gadolinium-enhanced magnetic resonance arthrography (MRA) is commonly applied to characterize morphological disorders of the hip. However, the reproducibility of retrieving anatomic landmarks on MRA scans and their correlation with intraarticular pathologies is unknown. A precise mapping system for the exact localization of hip pathomorphologies with radial MRA sequences is lacking. Therefore, the purpose of the study was the establishment and validation of a reproducible mapping system for radial sequences of hip MRA. Sixty-nine consecutive intraarticular gadolinium-enhanced hip MRAs were evaluated. Radial sequencing consisted of 14 cuts orientated along the axis of the femoral neck. Three orthopedic surgeons read the radial sequences independently. Each MRI was read twice with a minimum interval of 7 days from the first reading. The intra- and inter-observer reliability of the mapping procedure was determined. A clockwise system for hip MRA was established. The teardrop figure served to determine the 6 o'clock position of the acetabulum; the center of the greater trochanter served to determine the 12 o'clock position of the femoral head-neck junction. The intra- and inter-observer ICCs to retrieve the correct 6/12 o'clock positions were 0.906-0.996 and 0.978-0.988, respectively. The established mapping system for radial sequences of hip joint MRA is reproducible and easy to perform.

"One-pot" ethyl chloroformate derivatization and liquid-liquid extraction of reduced glutathione in erythrocyte and its quantitative GC-MS analysis.

PubMed

Manca, Alessandra; Alladio, Eugenio; Massarenti, Paola; Puccinelli, M Paola; De Francesco, Antonella; Del Grosso, Erika; Mengozzi, Giulio; Pazzi, Marco; Vincenti, Marco

2017-12-01

A simple "one-pot" derivatization and liquid-liquid extraction (LLE) procedure was developed for GC-MS analysis of reduced glutathione (GSH) analysis in erythrocytes. The metabolite was extracted by 5% (w/v) TCA, the supernatant treated with ECF and ethanol-pyridine media, the derivative separated and detected by gas chromatography-mass spectrometry using a short non-polar capillary GC column at a high column-head pressure. Total analysis time was 11min. The process was optimized by a Design of Experiment. The method was validated showing a good linearity over the 25.4-813.4μM concentration range, providing satisfactory results in terms of intra-day and inter-day precision as well as an optimal accuracy. The new method was evaluated in a pilot study involving patients with severe protein malnutrition. Comparison of this group with a group of healthy subjects revealed significantly lower GSH concentrations in erythrocytes in the former, thus proving that the described GC-MS method could be employed for fast and simple GSH analysis in clinical studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Extraction and derivatization of chemical weapons convention relevant aminoalcohols on magnetic cation-exchange resins.

PubMed

Singh, Varoon; Garg, Prabhat; Chinthakindi, Sridhar; Tak, Vijay; Dubey, Devendra Kumar

2014-02-14

Analysis and identification of nitrogen containing aminoalcohols is an integral part of the verification analysis of chemical weapons convention (CWC). This study was aimed to develop extraction and derivatization of aminoalcohols of CWC relevance by using magnetic dispersive solid-phase extraction (MDSPE) in combination with on-resin derivatization (ORD). For this purpose, sulfonated magnetic cation-exchange resins (SMRs) were prepared using magnetite nanoparticles as core, styrene and divinylbenzene as polymer coat and sulfonic acid as acidic cation exchanger. SMRs were successfully employed as extractant for targeted basic analytes. Adsorbed analytes were derivatized with hexamethyldisilazane (HMDS) on the surface of extractant. Derivatized (silylated) compounds were analyzed by GC-MS in SIM and full scan mode. The linearity of the method ranged from 5 to 200ngmL(-1). The LOD and LOQ ranged from 2 to 6ngmL(-1) and 5 to 19ngmL(-1) respectively. The relative standard deviation for intra-day repeatability and inter-day intermediate precision ranged from 5.1% to 6.6% and 0.2% to 7.6% respectively. Recoveries of analytes from spiked water samples from different sources varied from 28.4% to 89.3%. Copyright © 2014 Elsevier B.V. All rights reserved.

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

PubMed

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

2007-03-01

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

Determination of volatile compounds in cider apple juices using a covalently bonded ionic liquid coating as the stationary phase in gas chromatography.

PubMed

Pello-Palma, Jairo; González-Álvarez, Jaime; Gutiérrez-Álvarez, María Dolores; Dapena de la Fuente, Enrique; Mangas-Alonso, Juan José; Méndez-Sánchez, Daniel; Gotor-Fernández, Vicente; Arias-Abrodo, Pilar

2017-04-01

A chromatographic method for the separation of volatile compounds in Asturian cider apple juices has been developed. For this separation purpose, a monocationic imidazolium-based ionic liquid bearing a reactive terminal iodine atom was synthesized by a quaternization-anion exchange chemical sequence. Next, the gas chromatography (GC) stationary phase was prepared by covalently linking the imidazolium monolith to the reactive silanol groups of the inner capillary wall at 70 °C. This coated GC column exhibited good thermal stability (290 °C), as well as good efficiency (2000 plates/m) in the separation of volatile compounds from Asturian apple cider juices, and was characterized using the Abraham solvation parameter model. The intra-day and inter-day precision of the chromatographic method was evaluated, obtaining relative standard deviations from 3.7 to 12.9% and from 7.4 to 18.0%, respectively. Furthermore, recoveries from 82.5 to 122% were achieved. Graphical Abstract Covalent bonding of an ionic liquid to inner column wall led to a great improvement of the separation efficiencies of stationary phases in gas chromatography.

Molecularly imprinted solid-phase extraction for determination of tilmicosin in feed using high performance liquid chromatography.

PubMed

Zheng, Yaqiu; Liu, Yahong; Guo, Hongbin; He, Limin; Fang, Binghu; Zeng, Zhenling

2011-04-01

A simple, sensitive and reproducible molecularly imprinted solid-phase extraction (MISPE) coupled with high performance liquid chromatographic method was developed for monitoring tilmicosin in feeds. The polymers were prepared using tylosin as mimic template molecule, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linking monomer, and chloroform as a solvent by bulk polymerization. Under the optimum MISPE conditions, the novel polymer sorbent can selectively extract and enrich tilmicosin from variety of feeds. The MISPE cartridge was better than non-imprinted, C(18) and HLB cartridges in terms of both recovery and precision. Mean recoveries of tilmicosin from five kinds of feeds spiked at 1, 10 and 50 mg kg(-1) ranged from 76.9% to 95.6%, with intra-day and inter-day relative standard deviation less than 7.6%. The linearity was ranged from 1.0 to 100 mg L(-1) for matrix standard solution (r=0.9990). The limit of detection was approximately 0.35 mg kg(-1) and the limit of quantification was approximately 0.98 mg kg(-1). There was cleaner chromatogram by using MISPE than C(18) and HLB SPE. Copyright © 2011 Elsevier B.V. All rights reserved.

A rapid liquid chromatography tandem mass spectrometry-based method for measuring propranolol on dried blood spots.

PubMed

Della Bona, Maria Luisa; Malvagia, Sabrina; Villanelli, Fabio; Giocaliere, Elisa; Ombrone, Daniela; Funghini, Silvia; Filippi, Luca; Cavallaro, Giacomo; Bagnoli, Paola; Guerrini, Renzo; la Marca, Giancarlo

2013-05-05

Propranolol, a non-selective beta blocker drug, is used in young infants and newborns for treating several heart diseases; its pharmacokinetics has been extensively evaluated in adult patients using extrapolation to treat pediatric population. The purpose of the present study was to develop and validate a method to measure propranolol levels in dried blood spots. The analysis was performed by using liquid chromatography/tandem mass spectrometry operating in multiple reaction monitoring mode. The calibration curve in matrix was linear in the concentration range of 2.5-200 μg/L with correlation coefficient r=0.9996. Intra-day and inter-day precisions and biases were less than 8.0% (n=10) and 11.5% (n=10) respectively. The recoveries ranged from 94 to 100% and the matrix effect did not result in a severe signal suppression. Propranolol on dried blood spot showed a good stability at three different temperatures for one month. This paper describes a micromethod for measuring propranolol levels on dried blood spot, which determines a great advantage in neonates or young infants during pharmacokinetic studies because of less invasive sampling and small blood volume required. Copyright © 2013 Elsevier B.V. All rights reserved.

Development of a fiber coating based on molecular sol-gel imprinting technology for selective solid-phase micro extraction of caffeine from human serum and determination by gas chromatography/mass spectrometry.

PubMed

Rajabi Khorrami, Afshin; Rashidpur, Amene

2012-05-21

In this work, a molecular sol-gel imprinting approach has been introduced to produce a fiber coating for selective direct immersion solid-phase microextraction (SPME) of caffeine. The polymerization mixture was composed of vinyl trimethoxysilane and methacrylic acid as vinyl sol-gel precursor and functional monomer, respectively. Caffeine was used as template molecule during polymerization process. The prepared fibers could be coupled directly to gas chromatography/mass spectrometry (GC/MS) and used for trace analysis of caffeine in a complex sample such as human serum. The parameters influencing SPME such as time, temperature and stirring speed were optimized. The prepared coating showed good selectivity towards caffeine in the presence of some structurally related compounds. Also, it offered high imprinting capability in comparison to bare fiber and non-imprinted coating. Linear range for caffeine detection was 1-80 μg mL(-1) and the limit of detection was 0.1 μg mL(-1). The intra-day and inter-day precisions of the peak areas for five replicates were 10 and 16%, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of cyanide in bamboo shoots by microdiffusion combined with ion chromatography–pulsed amperometric detection

PubMed Central

Ding, Ming

2018-01-01

A practical method for the determination of cyanide in bamboo shoots has been developed using microdiffusion preparation integrated with ion chromatography–pulsed amperometric detection (IC-PAD). Cyanide was released from bamboo shoots after Conway cell microdiffusion, and then analysed by IC-PAD. In comparison with the previously reported methods, derivatization and ion-pairing agent addition were not required in this proposed microdiffusion combined with IC-PAD method. The microdiffusion parameters were optimized including hydrolysis systems, temperature, time, and so on. Under the optimum conditions, the linear range of the calibration curve for cyanide was 0.2–200.0 µg kg−1 with satisfactory correlation coefficients of 0.9996 and the limit of detection was 0.2 µg kg−1 (S/N = 3). The spiked recovery range was from 92.8 to 98.6%. The intra-day and inter-day relative standard deviations of cyanide were 2.7–14.9% and 3.0–18.3%, respectively. This method was proved to be convenient in operation with high sensitivity, precision and accuracy, and was successfully applied in the determination of cyanide in bamboo shoot samples. PMID:29765664

Determination of ibuprofen enantiomers in breast milk using vortex-assisted matrix solid-phase dispersion and direct chiral liquid chromatography.

PubMed

León-González, M E; Rosales-Conrado, N

2017-09-08

A mixture of β-cyclodextrin (β-CD) and primary and secondary amine (PSA) sorbents was employed for the extraction and quantification of ibuprofen enantiomers from human breast milk, combining a vortex-assisted matrix solid-phase dispersion method (MSPD) and direct chiral liquid chromatography (CLC) with ultraviolet detection (UV). The MSPD sample preparation procedure was optimized focusing on both the type and amount of dispersion/sorption sorbents and the nature of the elution solvent, in order to obtain acceptable recoveries and avoiding enantiomer conversion. These MSPD parameters were optimized with the aid of an experimental design approach. Hence, a factorial design was used for identification of the main variables affecting the extraction process of ibuprofen enantiomers. Under optimum selected conditions, MSPD combined with direct CLC-UV was successfully applied for ibuprofen enantiomeric determination in breast milk at enantiomer levels between 0.15 and 6.0μgg -1 . The proposed analytical method also provided good repeatability, with relative standard deviations of 6.4% and 8.3% for the intra-day and inter-day precision, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Flotation/ultrasound-assisted microextraction followed by HPLC for determination of fat-soluble vitamins in multivitamin pharmaceutical preparations.

PubMed

Shahdousti, Parvin; Aghamohammadi, Mohammad

2018-04-01

Dissolved carbon dioxide flotation-emulsification microextraction technique coupled with high-performance liquid chromatography was developed for separation and determination of fat-soluble vitamins (A, D 3 , E, and K 3 ) in multivitamin pharmaceutical preparations. Dissolved carbon dioxide flotation was used to break up the emulsion of extraction solvent in water and to collect the extraction solvent on the surface of aqueous sample in narrowed capillary part of extraction cell. Carbon dioxide bubbles were generated in situ through the addition of 300 μL of concentrated hydrochloric acid into the alkaline sample solution at pH = 11.5 (1% w/v sodium carbonate), which was sonicated to intensify the carbon dioxide bubble generation. Several factors affecting the extraction process were optimized. Under the optimal conditions, the limits of detection were 0.11, 0.47, 0.20 and 0.35 μg/L for A, E, D 3 , and K 3 vitamins in water samples, respectively. The inter-day and intra-day precision of the proposed method were evaluated in terms of the relative standard deviation and were <10.5%. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous quantitative determination of six active components in traditional Chinese medicinal preparation Cerebralcare Granule® by RP-HPLC coupled with diode array detection for quality control.

PubMed

Wang, Xiang-yang; Ma, Xiao-hui; Li, Wei; Chu, Yang; Guo, Jia-hua; Zhou, Shui-ping; Zhu, Yong-hong

2014-09-01

A simple, accurate and reliable method for the simultaneous separation and determination of six active components (protocatechuic acid, chlorogenic acid, caffeic acid, paeoniflorin, ferulic acid and rosmarinic acid) in traditional Chinese medicinal preparation Cerebralcare Granule(®) (CG) was developed using reverse-phase high-performance liquid chromatography coupled with diode array detector detection. The chromatographic separation was performed on a Hypersil GOLD C18 column with aqueous formic acid (0.1%, v/v) and acetonitrile as mobile phase at a flow rate of 0.2 ml/min at 30 °C. Because of the different UV characteristics of these components, change detection wavelength method was used for quantitative analysis. All of the analytes showed good linearity (r > 0.9992). The established method showed good precision and relative standard deviations (%) for intra-day and inter-day variations of 0.15-1.81 and 0.11-1.98%, respectively. The validated method was successfully applied to the simultaneously determination of six active components in CG from different batches. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

An optimized high-performance liquid chromatography (HPLC) method for benzoylmesaconine determination in Radix Aconiti Lateralis Preparata (Fuzi, aconite roots) and its products

PubMed Central

Xie, Ying; Zhou, Hua; Wong, Yuen Fan; Liu, Zhongqiu; Xu, Hongxi; Jiang, Zhihong; Liu, Liang

2008-01-01

Background Benzoylmesaconine (BMA) is the main Aconitum alkaloid in Radix Aconiti Lateralis Preparata (Fuzi, aconite roots) with potent pharmacological activities, such as analgesia and anti-inflammation. The present study developed a simple and reliable method using BMA as a marker compound for the quality control of processed aconite roots and their products. Methods After extraction, a high-performance liquid chromatography (HPLC) determination of BMA was conducted on a RP-C18 column by gradient elution with acetonitrile and aqueous phase, containing 0.1% phosphoric acid adjusted with triethylamine to pH 3.0. Results A distinct peak profile was obtained and separation of BMA was achieved. Method validation showed that the relative standard deviations (RSDs) of the precision of BMA in all intra-day and inter-day assays were less than 1.36%, and that the average recovery rate was 96.95%. Quantitative analysis of BMA showed that the content of BMA varied significantly in processed aconite roots and their products. Conclusion This HPLC method using BMA as a marker compound is applicable to the quality control of processed aconite roots and their products. PMID:18513409

Analysis of repaglinide enantiomers in pharmaceutical formulations by capillary electrophoresis using 2,6-di-o-methyl-β-cyclodextrin as a chiral selector.

PubMed

Li, Cen; Jiang, Ye

2012-09-01

This study used the general applicability of 2,6-didi-o-methyl-β-cyclodextrin (DM-β-CD) as the chiral selector in capillary electrophoresis for fast and efficient chiral separation of repaglinide enantiomers. A systematic study of the parameters affecting separation was performed with UV detection at 243 nm. The optimum conditions were determined to be 1.25% (w/v) DM-β-CD in 20 mM sodium phosphate (pH 2.5) as the running buffer and separation voltage at 20 kV. DM-β-CD had the best enantiomer resolution properties under the tested conditions, whereas other β-cyclodextrins showed inferior performances or no performance. The proposed method had a linear calibration curve in the concentration range of 12.5-400 µg/mL. The limit of detection was 100 ng/mL. The intra-day and inter-day precisions were 2.8 and 3.2%, respectively. Recoveries of 97.9-100.9% were obtained. The proposed method was fast and convenient, and was determined to be efficient for separating enantiomers and applicable for analyzing repaglinide enantiomers in quality control of pharmaceutical production.

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

PubMed

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

2016-07-01

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

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

PubMed

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

2010-10-01

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

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

PubMed

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

2011-09-01

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

Recent results of Daya Bay reactor neutrino experiment

NASA Astrophysics Data System (ADS)

Leitner, R.; Daya Bay Collaboration

2017-04-01

The Daya Bay reactor neutrino experiment has been designed to precisely measure the least known neutrino mixing angle θ13. In March 2012, Daya Bay collaboration announced [Daya Bay Collaboration (F. P. An et al.), Observation of electron-antineutrino disappearance at Daya Bay, Phys. Rev. Lett. 108 (2012) 171803] the observation of non-zero value of sin2 ⁡ 2θ13. Because of large statistics of detected antineutrinos and excellent performance of the experiment, Daya Bay continuously improves the precision of world best measurement of sin2 ⁡ 2θ13. In addition it provides results on neutrino mass splitting Δ mee2 competitive with measurements of other experiments, results on precise measurement of reactor fluxes and on limits of the existence of hypothetical fourth neutrino. In this paper, we report the results available by the time of the 6th Capri workshop: the measurement of oscillation parameters sin2 ⁡ (2θ13) = 0.084 ± 0.005 and | Δmee2 | = (2.42 ± 0.11) ×10-3eV2 [Daya Bay Collaboration (F. P. An et al.), New Measurement of Antineutrino Oscillation with the Full Detector Configuration at Daya Bay, Phys. Rev. Lett. 115 (2015) no. 11, 111802], searches for sterile neutrinos [Daya Bay Collaboration (F. P. An et al.) Search for a Light Sterile Neutrino at Daya Bay, Phys. Rev. Lett. 113 (2014) 141802] and precise measurement of reactor neutrino flux [Daya Bay Collaboration (F. P. An et al.), Measurement of the Reactor Anti-neutrino Flux and Spectrum at Daya Bay, Phys. Rev. Lett. 116 (2016) no. 6, 061801]. These are based on 621 days of measurement, most of the data has been taken in full detector configuration. More precise results [Daya Bay Collaboration (F. P. An et al.), Measurement of electron antineutrino oscillation based on 1230 days of operation of the Daya Bay experiment, arxiv:arXiv:1610.04802] with 1230 days of operation have been presented few weeks later at the Neutrino 2016 conference.

Enantioselective determination of 3-n-butylphthalide (NBP) in human plasma by liquid chromatography on a teicoplanin-based chiral column coupled with tandem mass spectrometry.

PubMed

Diao, Xingxing; Ma, Zhiyu; Lei, Peng; Zhong, Dafang; Zhang, Yifan; Chen, Xiaoyan

2013-11-15

A novel and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine the exposure of 3-n-butylphthalide (NBP) enantiomers in human plasma. The NBP enantiomers were extracted from human plasma using methyl tert-butyl ether. The baseline separation of R-(+)-NBP and S-(-)-NBP was achieved within 11.0min using a teicoplanin-based Astec Chirobiotic T column (250mm×4.6mm i.d., 5μm) under isocratic conditions at a flow rate of 0.6mL/min. The selection of the chiral stationary phase and the effect of the mobile phase composition on the resolution of the enantiomers were discussed. The selectivity, linearity, precision, accuracy, matrix effect, recovery, and stability were evaluated under optimized conditions. The LC-MS/MS method using 200μL of human plasma was linear over the concentration range of 5.00-400ng/mL for each enantiomer. The lower limit of quantification (LLOQ) for both enantiomers was 5.00ng/mL. The intra- and inter-assay precision values of the replicated quality control samples were within 8.0% for each enantiomer. The mean accuracy values for the quality control samples were within ±6.1% of the nominal values for R-(+)-NBP and S-(-)-NBP. No chiral inversion was observed during sample storage, preparation, and analysis. The method proved suitable for enantioselective pharmacokinetic studies of NBP after an oral administration of a therapeutic dose of racemic NBP. Copyright © 2013 Elsevier B.V. All rights reserved.

Modeling and Assessment of GPS/BDS Combined Precise Point Positioning.

PubMed

Chen, Junping; Wang, Jungang; Zhang, Yize; Yang, Sainan; Chen, Qian; Gong, Xiuqiang

2016-07-22

Precise Point Positioning (PPP) technique enables stand-alone receivers to obtain cm-level positioning accuracy. Observations from multi-GNSS systems can augment users with improved positioning accuracy, reliability and availability. In this paper, we present and evaluate the GPS/BDS combined PPP models, including the traditional model and a simplified model, where the inter-system bias (ISB) is treated in different way. To evaluate the performance of combined GPS/BDS PPP, kinematic and static PPP positions are compared to the IGS daily estimates, where 1 month GPS/BDS data of 11 IGS Multi-GNSS Experiment (MGEX) stations are used. The results indicate apparent improvement of GPS/BDS combined PPP solutions in both static and kinematic cases, where much smaller standard deviations are presented in the magnitude distribution of coordinates RMS statistics. Comparisons between the traditional and simplified combined PPP models show no difference in coordinate estimations, and the inter system biases between the GPS/BDS system are assimilated into receiver clock, ambiguities and pseudo-range residuals accordingly.

Connecting Digital Repeat Photography to Ecosystem Fluxes in Inland Pacific Northwest, US Cropping Systems

NASA Astrophysics Data System (ADS)

Russell, E.; Chi, J.; Waldo, S.; Pressley, S. N.; Lamb, B. K.; Pan, W.

2017-12-01

Diurnal and seasonal gas fluxes vary by crop growth stage. Digital cameras are increasingly being used to monitor inter-annual changes in vegetation phenology in a variety of ecosystems. These cameras are not designed as scientific instruments but the information they gather can add value to established measurement techniques (i.e. eddy covariance). This work combined deconstructed digital images with eddy covariance data from five agricultural sites (1 fallow, 4 cropped) in the inland Pacific Northwest, USA. The data were broken down with respect to crop stage and management activities. The fallow field highlighted the camera response to changing net radiation, illumination, and rainfall. At the cropped sites, the net ecosystem exchange, gross primary production, and evapotranspiration were correlated with the greenness and redness values derived from the images over the growing season. However, the color values do not change quickly enough to respond to day-to-day variability in the flux exchange as the two measurement types are based on different processes. The management practices and changes in phenology through the growing season were not visible within the camera data though the camera did capture the general evolution of the ecosystem fluxes.

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.

Value of ITS information for congestion avoidance in inter-modal transportation systems : phase II.

DOT National Transportation Integrated Search

2010-03-01

Our project has four major mile-stones for the second year: : Mile-stone #1: Develop Dynamic Inter-modal Transportation Optimization Models: For : mostly air-road network and inter-modal networks significant to OHIO : MICHIGAN regions and our col...

Event- and interval-based measurement of stuttering: a review.

PubMed

Valente, Ana Rita S; Jesus, Luis M T; Hall, Andreia; Leahy, Margaret

2015-01-01

Event- and interval-based measurements are two different ways of computing frequency of stuttering. Interval-based methodology emerged as an alternative measure to overcome problems associated with reproducibility in the event-based methodology. No review has been made to study the effect of methodological factors in interval-based absolute reliability data or to compute the agreement between the two methodologies in terms of inter-judge, intra-judge and accuracy (i.e., correspondence between raters' scores and an established criterion). To provide a review related to reproducibility of event-based and time-interval measurement, and to verify the effect of methodological factors (training, experience, interval duration, sample presentation order and judgment conditions) on agreement of time-interval measurement; in addition, to determine if it is possible to quantify the agreement between the two methodologies The first two authors searched for articles on ERIC, MEDLINE, PubMed, B-on, CENTRAL and Dissertation Abstracts during January-February 2013 and retrieved 495 articles. Forty-eight articles were selected for review. Content tables were constructed with the main findings. Articles related to event-based measurements revealed values of inter- and intra-judge greater than 0.70 and agreement percentages beyond 80%. The articles related to time-interval measures revealed that, in general, judges with more experience with stuttering presented significantly higher levels of intra- and inter-judge agreement. Inter- and intra-judge values were beyond the references for high reproducibility values for both methodologies. Accuracy (regarding the closeness of raters' judgements with an established criterion), intra- and inter-judge agreement were higher for trained groups when compared with non-trained groups. Sample presentation order and audio/video conditions did not result in differences in inter- or intra-judge results. A duration of 5 s for an interval appears to be an acceptable agreement. Explanation for high reproducibility values as well as parameter choice to report those data are discussed. Both interval- and event-based methodologies used trained or experienced judges for inter- and intra-judge determination and data were beyond the references for good reproducibility values. Inter- and intra-judge values were reported in different metric scales among event- and interval-based methods studies, making it unfeasible to quantify the agreement between the two methods. © 2014 Royal College of Speech and Language Therapists.

Inter-comparison of boron concentration measurements at INFN-University of Pavia (Italy) and CNEA (Argentina).

PubMed

Portu, Agustina; Postuma, Ian; Gadan, Mario Alberto; Saint Martin, Gisela; Olivera, María Silvina; Altieri, Saverio; Protti, Nicoletta; Bortolussi, Silva

2015-11-01

An inter-comparison of three boron determination techniques was carried out between laboratories from INFN-University of Pavia (Italy) and CNEA (Argentina): alpha spectrometry (alpha-spect), neutron capture radiography (NCR) and quantitative autoradiography (QTA). Samples of different nature were analysed: liquid standards, liver homogenates and tissue samples from different treatment protocols. The techniques showed a good agreement in a concentration range of interest in BNCT (1-100ppm), thus demonstrating their applicability as precise methods to quantify boron and determine its distribution in tissues. Copyright © 2015 Elsevier Ltd. All rights reserved.

Detecting causality from online psychiatric texts using inter-sentential language patterns

PubMed Central

2012-01-01

Background Online psychiatric texts are natural language texts expressing depressive problems, published by Internet users via community-based web services such as web forums, message boards and blogs. Understanding the cause-effect relations embedded in these psychiatric texts can provide insight into the authors’ problems, thus increasing the effectiveness of online psychiatric services. Methods Previous studies have proposed the use of word pairs extracted from a set of sentence pairs to identify cause-effect relations between sentences. A word pair is made up of two words, with one coming from the cause text span and the other from the effect text span. Analysis of the relationship between these words can be used to capture individual word associations between cause and effect sentences. For instance, (broke up, life) and (boyfriend, meaningless) are two word pairs extracted from the sentence pair: “I broke up with my boyfriend. Life is now meaningless to me”. The major limitation of word pairs is that individual words in sentences usually cannot reflect the exact meaning of the cause and effect events, and thus may produce semantically incomplete word pairs, as the previous examples show. Therefore, this study proposes the use of inter-sentential language patterns such as ≪broke up, boyfriend>,

Transient inter-cellular polymeric linker.

PubMed

Ong, Siew-Min; He, Lijuan; Thuy Linh, Nguyen Thi; Tee, Yee-Han; Arooz, Talha; Tang, Guping; Tan, Choon-Hong; Yu, Hanry

2007-09-01

Three-dimensional (3D) tissue-engineered constructs with bio-mimicry cell-cell and cell-matrix interactions are useful in regenerative medicine. In cell-dense and matrix-poor tissues of the internal organs, cells support one another via cell-cell interactions, supplemented by small amount of the extra-cellular matrices (ECM) secreted by the cells. Here we connect HepG2 cells directly but transiently with inter-cellular polymeric linker to facilitate cell-cell interaction and aggregation. The linker consists of a non-toxic low molecular-weight polyethyleneimine (PEI) backbone conjugated with multiple hydrazide groups that can aggregate cells within 30 min by reacting with the aldehyde handles on the chemically modified cell-surface glycoproteins. The cells in the cellular aggregates proliferated; and maintained the cortical actin distribution of the 3D cell morphology while non-aggregated cells died over 7 days of suspension culture. The aggregates lost distinguishable cell-cell boundaries within 3 days; and the ECM fibers became visible around cells from day 3 onwards while the inter-cellular polymeric linker disappeared from the cell surfaces over time. The transient inter-cellular polymeric linker can be useful for forming 3D cellular and tissue constructs without bulk biomaterials or extensive network of engineered ECM for various applications.

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.

Developing and evaluating an automated appendicitis risk stratification algorithm for pediatric patients in the emergency department.

PubMed

Deleger, Louise; Brodzinski, Holly; Zhai, Haijun; Li, Qi; Lingren, Todd; Kirkendall, Eric S; Alessandrini, Evaline; Solti, Imre

2013-12-01

To evaluate a proposed natural language processing (NLP) and machine-learning based automated method to risk stratify abdominal pain patients by analyzing the content of the electronic health record (EHR). We analyzed the EHRs of a random sample of 2100 pediatric emergency department (ED) patients with abdominal pain, including all with a final diagnosis of appendicitis. We developed an automated system to extract relevant elements from ED physician notes and lab values and to automatically assign a risk category for acute appendicitis (high, equivocal, or low), based on the Pediatric Appendicitis Score. We evaluated the performance of the system against a manually created gold standard (chart reviews by ED physicians) for recall, specificity, and precision. The system achieved an average F-measure of 0.867 (0.869 recall and 0.863 precision) for risk classification, which was comparable to physician experts. Recall/precision were 0.897/0.952 in the low-risk category, 0.855/0.886 in the high-risk category, and 0.854/0.766 in the equivocal-risk category. The information that the system required as input to achieve high F-measure was available within the first 4 h of the ED visit. Automated appendicitis risk categorization based on EHR content, including information from clinical notes, shows comparable performance to physician chart reviewers as measured by their inter-annotator agreement and represents a promising new approach for computerized decision support to promote application of evidence-based medicine at the point of care.

[Reality of Inter-Professional Cooperation in Medical Day Care Facilities - What is Visible from the Level of Inter-Professional Cooperation].

PubMed

Ugai, Chizuru; Hata, Kiyomi

2015-12-01

In order to improve the quality of life of patients with moderate to severe symptoms who are highly dependent on medical care and to reduce the physical and psychological burden on family members, at medical day care facilities, care and services, such as functional training, is provided to improve daily life for patients in need of significant care who have intractable diseases under the Long-Term Care Insurance Act; home care patients, such as those in the final stages of cancer; and severely mentally and physically handicapped children under the Child Welfare Act. This study conducted semi-structured interviews with 15 nurses working in medical day care facilities with the objective of clarifying the reality of inter-professional cooperation of nurses working in these facilities and contributing to delivery of high-quality care. The results of the study revealed that the level of inter-professional cooperation of nurses at medical day care facilities was high and that professions that are involved in cooperation include visiting nurses, doctors, medical staff, such as physical therapists, caregivers, and welfare professions, such as care managers. The study also showed that the contents of cooperation include information exchange, information sharing, continuation of care, implementation of care that respects the intentions of the patient, care proposals, and guidance and control regarding care.

Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis.

PubMed

Larsen, K K; Wielandt, D; Schiller, M; Bizzarro, M

2016-04-22

Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr(3+), CrCl(2+) and CrCl2(+)) with equilibrium mass-dependent isotope fractionation spanning a range of ∼1‰/amu and consistent with theory. The heaviest isotopes partition into Cr(3+), intermediates in CrCl(2+) and the lightest in CrCl2(+)/CrCl3°. Thus, for a typical reported loss of ∼25% Cr (in the form of Cr(3+)) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected (53)Cr/(52)Cr (μ(53)Cr* of 5.2 ppm) and (54)Cr/(52)Cr (μ(54)Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr(3+) by >5 days exposure to HNO3H2O2 solutions at room temperature, resulting in >∼98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a chromatographic elution strategy that takes advantage of the slow reaction kinetics of de-chlorination of Cr in dilute HCl at room temperature. These procedures significantly improve cation chromatographic purification of Cr over previous methods and allow for high-purity Cr isotope analysis with a total recovery of >95%. Copyright © 2016 Elsevier B.V. All rights reserved.

Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

PubMed Central

Larsen, K.K.; Wielandt, D.; Schiller, M.; Bizzarro, M.

2016-01-01

Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr3+, CrCl2+ and CrCl2+) with equilibrium mass-dependent isotope fractionation spanning a range of ~1‰/amu and consistent with theory. The heaviest isotopes partition into Cr3+, intermediates in CrCl2+ and the lightest in CrCl2+/CrCl3°. Thus, for a typical reported loss of ~25% Cr (in the form of Cr3+) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected 53Cr/52Cr (μ53 Cr* of 5.2 ppm) and 54Cr/52Cr (μ54Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr3+ by >5 days exposure to HNO3 —H2O2 solutions at room temperature, resulting in >~98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a chromatographic elution strategy that takes advantage of the slow reaction kinetics of de-chlorination of Cr in dilute HCl at room temperature. These procedures significantly improve cation chromatographic purification of Cr over previous methods and allow for high-purity Cr isotope analysis with a total recovery of >95%. PMID:27036208

Recognition of the epicardial breakthrough on body surface isopotential maps: influence of the inter-electrode distance on the patterns reflecting the epicardial breakthrough.

PubMed

Toyama, J; Tabata, O

1981-10-01

The epicardial breakthrough can be recognized from the localized depression of the body surface potential, which is characterized by a localized bend of the equipotential lines or a send-minimum on isopotential maps. Recognition of epicardial breakthrough with isopotential maps enables us to diagnose location of the block site of the bundle branch blocks more precisely than by ECG or VCG. However, the optimum inter-electrode distance for detection of such a localized potential has not been determined. In the present study, influence of the inter-electrode distance on the characteristic patterns reflecting the epicardial breakthrough was studied on 16 healthy persons using 9 x 9 electrode arrays with inter-electrode distance of 1.25 cm, 5 x 5 with 2.5 cm, and 3 x 3 with 5 cm. Breakthrough was recognized in 15 out of 16 cases (94%) on maps recorded with electrode arrays with inter-electrode distance of 1.25 and 2.5 cm. However, detectability of the breakthrough was reduced to 10 out of 16 cases (63%) with electrode array having inter-electrode distance of 5 cm. In conclusion, it is preferable to use an electrode array with an inter-electrode distance of no more than 2.5 cm for the purpose of breakthrough recognition.

Free Radicals in Precision Cut Bovine Testicle Slices: Effects of 1,3,5 Trinitrobenzene Measured by Electron Paramagnetic Resonance.

DTIC Science & Technology

1996-04-01

toluene or dinitrotoluene and toluene diamine have oligoasthenoteratozoospermia ( Radike , 1985). Oligoasthenoteratozoospermiais a condition of...transfer interations between Superoxide ion and organic compounds. J. Phys Chem 77: 1722-1724. Radike , M. Reproductive Toxicology Chpterl6 In

"Center punch" and "whole spot" bioanalysis of apixaban in human dried blood spot samples by UHPLC-MS/MS.

PubMed

Zheng, Naiyu; Yuan, Long; Ji, Qin C; Mangus, Heidi; Song, Yan; Frost, Charles; Zeng, Jianing; Aubry, Anne-Françoise; Arnold, Mark E

2015-04-15

Apixaban (Eliquis™) was developed by Bristol-Myers Squibb (BMS) and Pfizer to use as an antithrombotic/anticoagulant agent and has been recently approved for the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation. A clinical study of apixaban, sponsored by BMS and Pfizer, included a pilot exploratory portion to evaluate the potential for future drug concentration monitoring using dried blood spot (DBS) sample collection. For DBS sample collection, a fixed blood volume was dispensed onto a DBS card by either regular volumetric pipette (venous blood collection) or capillary dispenser (finger prick blood collection). A 96-well semi-automated liquid-liquid extraction sample preparation procedure was developed to provide clean extracts for UHPLC-MS/MS quantitation. Assays using both partial-spot center punch and whole spot punch were developed and validated. The linear dynamic ranges for all the analyses were from 0.5 to 500 ng/mL. The coefficient of determination (r(2)) values was >0.9944 for all the validation runs. For the center punch approach, the intra-assay precision (%CV) was within 4.4% and inter-assay precision was within 2.6%. The assay accuracy, expressed as %Dev., was within ± 5.4% of the nominal concentrations. One accuracy and precision run was performed using the whole spot approach, the intra-assay precision (%CV) was within 7.1% and the accuracy was within ± 8.0% of the nominal concentrations. In contrast to the center punch approach, the whole spot approach eliminated the effect of hematocrit and high lipids on the analysis of apixaban in human DBS when an accurate sample blood volume was collected on DBS cards. Copyright © 2015 Elsevier B.V. All rights reserved.

Automated simultaneous measurement of the δ(13) C and δ(2) H values of methane and the δ(13) C and δ(18) O values of carbon dioxide in flask air samples using a new multi cryo-trap/gas chromatography/isotope ratio mass spectrometry system.

PubMed

Brand, Willi A; Rothe, Michael; Sperlich, Peter; Strube, Martin; Wendeberg, Magnus

2016-07-15

The isotopic composition of greenhouse gases helps to constrain global budgets and to study sink and source processes. We present a new system for high-precision stable isotope measurements of carbon, hydrogen and oxygen in atmospheric methane and carbon dioxide. The design is intended for analyzing flask air samples from existing sampling programs without the need for extra sample air for methane analysis. CO2 and CH4 isotopes are measured simultaneously using two isotope ratio mass spectrometers, one for the analysis of δ(13) C and δ(18) O values and the second one for δ(2) H values. The inlet carousel delivers air from 16 sample positions (glass flasks 1-5 L and high-pressure cylinders). Three 10-port valves take aliquots from the sample stream. CH4 from 100-mL air aliquots is preconcentrated in 0.8-mL sample loops using a new cryo-trap system. A precisely calibrated working reference air is used in parallel with the sample according to the Principle of Identical Treatment. It takes about 36 hours for a fully calibrated analysis of a complete carousel including extractions of four working reference and one quality control reference air. Long-term precision values, as obtained from the quality control reference gas since 2012, account for 0.04 ‰ (δ(13) C values of CO2 ), 0.07 ‰ (δ(18) O values of CO2 ), 0.11 ‰ (δ(13) C values of CH4 ) and 1.0 ‰ (δ(2) H values of CH4 ). Within a single day, the system exhibits a typical methane δ(13) C standard deviation (1σ) of 0.06 ‰ for 10 repeated measurements. The system has been in routine operation at the MPI-BGC since 2012. Consistency of the data and compatibility with results from other laboratories at a high precision level are of utmost importance. A high sample throughput and reliability of operation are important achievements of the presented system to cope with the large number of air samples to be analyzed. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Reproducibility of cine displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance for measuring left ventricular strains, torsion, and synchrony in mice.

PubMed

Haggerty, Christopher M; Kramer, Sage P; Binkley, Cassi M; Powell, David K; Mattingly, Andrea C; Charnigo, Richard; Epstein, Frederick H; Fornwalt, Brandon K

2013-08-27

Advanced measures of cardiac function are increasingly important to clinical assessment due to their superior diagnostic and predictive capabilities. Cine DENSE cardiovascular magnetic resonance (CMR) is ideal for quantifying advanced measures of cardiac function based on its high spatial resolution and streamlined post-processing. While many studies have utilized cine DENSE in both humans and small-animal models, the inter-test and inter-observer reproducibility for quantification of advanced cardiac function in mice has not been evaluated. This represents a critical knowledge gap for both understanding the capabilities of this technique and for the design of future experiments. We hypothesized that cine DENSE CMR would show excellent inter-test and inter-observer reproducibility for advanced measures of left ventricular (LV) function in mice. Five normal mice (C57BL/6) and four mice with depressed cardiac function (diet-induced obesity) were imaged twice, two days apart, on a 7T ClinScan MR system. Images were acquired with 15-20 frames per cardiac cycle in three short-axis (basal, mid, apical) and two long-axis orientations (4-chamber and 2-chamber). LV strain, twist, torsion, and measures of synchrony were quantified. Images from both days were analyzed by one observer to quantify inter-test reproducibility, while inter-observer reproducibility was assessed by a second observer's analysis of day-1 images. The coefficient of variation (CoV) was used to quantify reproducibility. LV strains and torsion were highly reproducible on both inter-observer and inter-test bases with CoVs ≤ 15%, and inter-observer reproducibility was generally better than inter-test reproducibility. However, end-systolic twist angles showed much higher variance, likely due to the sensitivity of slice location within the sharp longitudinal gradient in twist angle. Measures of synchrony including the circumferential (CURE) and radial (RURE) uniformity of strain indices, showed excellent reproducibility with CoVs of 1% and 3%, respectively. Finally, peak measures (e.g., strains) were generally more reproducible than the corresponding rates of change (e.g., strain rate). Cine DENSE CMR is a highly reproducible technique for quantification of advanced measures of left ventricular cardiac function in mice including strains, torsion and measures of synchrony. However, myocardial twist angles are not reproducible and future studies should instead report torsion.

The expression of the skeletal muscle force-length relationship in vivo: a simulation study.

PubMed

Winter, Samantha L; Challis, John H

2010-02-21

The force-length relationship is one of the most important mechanical characteristics of skeletal muscle in humans and animals. For a physiologically realistic joint range of motion and therefore range of muscle fibre lengths only part of the force-length curve may be used in vivo, i.e. only a section of the force-length curve is expressed. A generalised model of a mono-articular muscle-tendon complex was used to examine the effect of various muscle architecture parameters on the expressed section of the force-length relationship for a 90 degrees joint range of motion. The parameters investigated were: the ratio of tendon resting length to muscle fibre optimum length (L(TR):L(F.OPT)) (varied from 0.5 to 11.5), the ratio of muscle fibre optimum length to average moment arm (L(F.OPT):r) (varied from 0.5 to 5), the normalised tendon strain at maximum isometric force (c) (varied from 0 to 0.08), the muscle fibre pennation angle (theta) (varied from 0 degrees to 45 degrees) and the joint angle at which the optimum muscle fibre length occurred (phi). The range of values chosen for each parameter was based on values reported in the literature for five human mono-articular muscles with different functional roles. The ratios L(TR):L(F.OPT) and L(F.OPT):r were important in determining the amount of variability in the expressed section of the force-length relationship. The modelled muscle operated over only one limb at intermediate values of these two ratios (L(TR):L(F.OPT)=5; L(F.OPT):r=3), whether this was the ascending or descending limb was determined by the precise values of the other parameters. It was concluded that inter-individual variability in the expressed section of the force-length relationship is possible, particularly for muscles with intermediate values of L(TR):L(F.OPT) and L(F.OPT):r such as the brachialis and vastus lateralis. Understanding the potential for inter-individual variability in the expressed section is important when using muscle models to simulate movement. (c) 2009 Elsevier Ltd. All rights reserved.

Values, inter-attitudinal structure, and attitude change: value accessibility can increase a related attitude's resistance to change.

PubMed

Blankenship, Kevin L; Wegener, Duane T; Murray, Renee A

2015-12-01

Accessibility is one of the most basic structural properties of an attitude and an important factor to consider in attitude strength. Despite its importance, relatively little work has examined the role of attitude accessibility in an inter-attitudinal context, particularly as it relates to the strength of related attitudes in the network. The present research examines accessibility as a property of one attitude (toward an abstract goal or end-state, that is, a value) that might influence the strength of a different but related attitude (toward a social policy conceptually related to the value). In Study 1, a highly accessible evaluative component of a value increased resistance to change of attitudes and behavioral intentions toward a social policy related to that value. Similarly, a manipulation of value accessibility (Studies 2 and 3) led to increased resistance of attitudes and behavioral intentions toward a social policy related to that value. Implications for the role of accessibility in inter-attitudinal strength are discussed. © 2015 by the Society for Personality and Social Psychology, Inc.

An evaluation of study design for estimating a time-of-day noise weighting

NASA Technical Reports Server (NTRS)

Fields, J. M.

1986-01-01

The relative importance of daytime and nighttime noise of the same noise level is represented by a time-of-day weight in noise annoyance models. The high correlations between daytime and nighttime noise were regarded as a major reason that previous social surveys of noise annoyance could not accurately estimate the value of the time-of-day weight. Study designs which would reduce the correlation between daytime and nighttime noise are described. It is concluded that designs based on short term variations in nighttime noise levels would not be able to provide valid measures of response to nighttime noise. The accuracy of the estimate of the time-of-day weight is predicted for designs which are based on long term variations in nighttime noise levels. For these designs it is predicted that it is not possible to form satisfactorily precise estimates of the time-of-day weighting.

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

PubMed

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

2017-10-20

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

A novel sample preparation procedure for effect-directed analysis of micro-contaminants of emerging concern in surface waters.

PubMed

Osorio, Victoria; Schriks, Merijn; Vughs, Dennis; de Voogt, Pim; Kolkman, Annemieke

2018-08-15

A novel sample preparation procedure relying on Solid Phase Extraction (SPE) combining different sorbent materials on a sequential-based cartridge was optimized and validated for the enrichment of 117 widely diverse contaminants of emerging concern (CECs) from surface waters (SW) and further combined chemical and biological analysis on subsequent extracts. A liquid chromatography coupled to high resolution tandem mass spectrometry LC-(HR)MS/MS protocol was optimized and validated for the quantitative analysis of organic CECs in SW extracts. A battery of in vitro CALUX bioassays for the assessment of endocrine, metabolic and genotoxic interference and oxidative stress were performed on the same SW extracts. Satisfactory recoveries ([70-130]%) and precision (< 30%) were obtained for the majority of compounds tested. Internal standard calibration curves used for quantification of CECs, achieved the linearity criteria (r 2 > 0.99) over three orders of magnitude. Instrumental limits of detection and method limits of quantification were of [1-96] pg injected and [0.1-58] ng/L, respectively; while corresponding intra-day and inter-day precision did not exceed 11% and 20%. The developed procedure was successfully applied for the combined chemical and toxicological assessment of SW intended for drinking water supply. Levels of compounds varied from < 10 ng/L to < 500 ng/L. Endocrine (i.e. estrogenic and anti-androgenic) and metabolic interference responses were observed. Given the demonstrated reliability of the validated sample preparation method, the authors propose its integration in an effect-directed analysis procedure for a proper evaluation of SW quality and hazard assessment of CECs. Copyright © 2018 Elsevier B.V. All rights reserved.

Development of an ultra-fast liquid chromatography-tandem mass spectrometry method for simultaneous determination of seven flavonoids in rat plasma: Application to a comparative pharmacokinetic investigation of Ginkgo biloba extract and single pure ginkgo flavonoids after oral administration.

PubMed

Wang, Tianyang; Xiao, Jie; Hou, Huiping; Li, Pei; Yuan, Ziyue; Xu, Huarong; Liu, Ran; Li, Qing; Bi, Kaishun

2017-08-15

For deeper pharmacokinetic investigation and further curative application of ginkgo flavonoids, a delicate, efficient and precise UFLC-MS/MS technique for synchronous quantitation of seven flavonoids, apigenin, luteolin, naringenin, quercetin, diosmetin, kaempferol and isorhamnetin in rat plasma has been established. After mixing with the internal standard (IS) linarin, bio-samples were pretreated via ethyl acetate for liquid-liquid extraction, then isolated at 0.2ml/min flow rate on a Venusil MP C 18 chromatographic column (100mm×2.1mm, 3μm) by means of gradient elution. 0.1% formic acid-water and methanol system was used as the mobile phase. Mass spectrometric inspection was conducted on a 4000Q UFLC-MS/MS system with turbo ion spray source in patterns of negative ion and multiple reaction-monitoring (MRM). All calibration curves proved favorable linearity (R 2 ≥0.9918) in linear ranges. Intra-day and inter-day precisions didn't exceed 14.0% for all the analytes, and the accuracy was within 6.9%. Extraction recoveries of analytes and IS were less than ±15.0% of nominal concentrations. This method has been under thorough and firm verification for a comparative pharmacokinetic research after gavage between Ginkgo biloba extract and single pure ginkgo flavonoids. The results demonstrated that there're evident pharmacokinetic discrepancies, and possible structural influences were innovatively proposed. Generally, substitution with 3-hydroxylation, a double bond in ring C, ring B methoxylation often confer longer onset period. The existence of ring B catechol group gives rise to faster clearance. Copyright © 2017. Published by Elsevier B.V.

[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.

Application of dispersive liquid-liquid microextraction coupled with vortex-assisted hydrophobic magnetic nanoparticles based solid-phase extraction for determination of aflatoxin M1 in milk samples by sensitive micelle enhanced spectrofluorimetry.

PubMed

Amoli-Diva, Mitra; Taherimaslak, Zohreh; Allahyari, Mehdi; Pourghazi, Kamyar; Manafi, Mohammad Hanif

2015-03-01

An efficient, simple and fast low-density solvent based dispersive liquid-liquid microextraction (LDS-DLLME) followed by vortex-assisted dispersive solid phase extraction (VA-D-SPE) has been developed as a new approach for extraction and preconcentration of aflatoxin M1 in milk samples prior to its micelle enhanced spectrofluorimetic determination. In this LDS-DLLME coupled VA-D-SPE method, milk samples were first treated with methanol/water (80:20, v/v) after removing the fat layer. This solvent was directly used as the dispersing solvent in DLLME along with using 1-heptanol (as a low-density solvent with respect to water) as the extracting solvent. In VA-D-SPE approach, hydrophobic oleic acid modified Fe3O4 nanoparticles were used to retrieve the analyte from the DLLME step. It is considerably that the target of VA-D-SPE was 1-heptanol rather than the aflatoxin M1 directly. The main parameters affecting the efficiency of LDS-DLLME and VA-D-SPE procedures and signal enhancement of aflatoxin M1 were investigated and optimized. Under the optimum conditions, the method was linear in the range from 0.02 to 200 µg L(-1) with the correlation coefficient (R(2)) of 0.9989 and detection limit of 13 ng L(-1). The intra-day precision was 2.9 and 4.3% and the inter-day precision was 2.1 and 3.3% for concentration of 2 and 50 µg L(-1) respectively. The developed method was applied for extraction and preconcentration of AFM1 in three commercially available milk samples and the results were compared with the official AOAC method. Copyright © 2014 Elsevier B.V. All rights reserved.