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Simultaneous Quantitation (simultaneous + quantitation)

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Chemistry	75%

Selected Abstracts

Simultaneous quantitation of three major triterpenoid glycosides in Centella asiatica extracts by high performance liquid chromatography with evaporative light scattering detection

BIOMEDICAL CHROMATOGRAPHY, Issue 2 2008
Feng-Lun Zhang
Abstract A high-performance liquid chromatography method with evaporative light scattering detection was established for simultaneous determination of three major triterpenoid glycosides, i.e. asiaticoside, madecassoside and asiaticoside-B, in Centella asiatica extracts. The optimal chromatographic conditions were achieved on a COSMOSIL 5C18 -MS-II column by constant elution with water (0.01% trifluoroacetic acid, v/v) and acetonitrile (1.0% methyl tert-butyl ether, 0.01% trifluoroacetic acid, v/v) (78:22) as mobile phase at a flow rate of 1.0 mL/min; the column temperature was 30°C. The evaporative light scattering detector was set at an evaporating temperature of 40°C and nitrogen gas pressure of 3.5 bar. The validation of the method included tests of linearity, sensitivity, precision, repeatability, stability and accuracy. All calibration curves showed good linear regression (r2 > 0.9993) within test ranges. The established method showed good precision and accuracy with overall intra-day and inter-day variations of 1.73,3.06 and 3.89%,4.92%, respectively, and overall recoveries of 97.63,99.39% for the three compounds analyzed. The method developed was successfully applied to quantify the main triterpenoid glycosides in Centella asiatica extracts from different companies. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Simultaneous quantification of 17 immune mediators in aqueous humour from patients with corneal rejection

ACTA OPHTHALMOLOGICA, Issue 6 2006
Mikkel Funding
Abstract. Purpose:, To simultaneously quantitate and compare the concentrations of 17 immune mediators: (1) the cytokines interleukin-1,, IL-2, IL-4, IL-5, IL-6, IL-7, IL-10, IL-12p70, IL-13, IL-17, tumour necrosis factor-,, interferon-,; (2) the growth factors granulocyte,monocyte colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF), and (3) the chemokines CXCL-8, monocyte chemoattractant protein-1, and macrophage inflammatory protein-1, in aqueous humour from patients with corneal rejection and patients with a non-inflammatory condition in the anterior chamber. Methods:, Aqueous humour was obtained by paracentesis of the anterior chamber in 14 patients with corneal rejection, three patients with cataract and six patients with Fuchs' endothelial dystrophy. Simultaneous quantitation of 17 mediators in 25 µl aqueous humour from each patient was performed by employing a highly sensitive Luminex® 100 multiplex array assay. Results:, All 17 immune mediators were detected in aqueous humour from rejection patients. The ranges of the immune mediators were determined. The immune mediators were significantly increased in aqueous humour from rejection patients compared with that from other patients. Conclusions:, The Luminex 100 multiplex array assay is very efficient in simultaneous quantitation of multiple immune mediators in small volumes of aqueous humour. A total of 17 immune mediators were increased in aqueous humour from rejection patients. This underlines the complex immunological interactions of the rejection process. [source]

Utility of porous graphitic carbon stationary phase in quantitative liquid chromatography/tandem mass spectrometry bioanalysis: quantitation of diastereomers in plasma

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2006
Yuan-Qing Xia
A major challenge in selecting an appropriate stationary phase for diastereomeric separation is that it is difficult to predict which of the commercially available stationary phases could achieve the required liquid chromatographic (LC) separation. This work describes the selection and evaluation of a porous graphitic carbon (PGC) column coupled with tandem mass spectrometry (MS/MS) for the simultaneous quantitation of an experimental drug candidate (I), its two diastereomeric metabolites (II and III), and its demethylated metabolite (IV) in rat plasma. In addition, we investigated the PGC column for the separation of another drug candidate (VI), its two diastereomeric metabolites (VII and VIII) and its ketone metabolite (IX). The PGC column showed excellent chromatographic resolution for the two diastereomers II and III, as well as for VII and VIII. In contrast, the required resolution for the diastereomers II and III could not be achieved using silica-bonded C18, C30, phenyl, perfluorinated, polar embedded and polar end-capped phases. The PGC column showed ruggedness with excellent reproducibility of retention times, peak symmetry and response over a period of more than 400 injections of a plasma acetonitrile-precipitation extract. Excellent accuracy and precision were achieved, with accuracy of 94,108% and intra- and inter-run precision within 9%. This work indicates that PGC is a valuable addition to the repertoire of LC columns used for quantitative LC/MS/MS bioanalysis, especially where the separation and quantitation of diastereomeric analytes is involved. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Development and validation of a highly sensitive and robust LC-ESI-MS/MS method for simultaneous quantitation of simvastatin acid, amlodipine and valsartan in human plasma: application to a clinical pharmacokinetic study,

BIOMEDICAL CHROMATOGRAPHY, Issue 6 2009
Addepalli V. Ramani
Abstract A high-throughput, simple, highly sensitive and specific LC-MS/MS method has been developed for simultaneous estimation of simvastatin acid (SA), amlodipine (AD) and valsartan (VS) with 500 µL of human plasma using deuterated simvastatin acid as an internal standard (IS). The API-4000 LC-MS/MS was operated under the multiple reaction-monitoring mode (MRM) using electrospray ionization. The assay procedure involved precipitation of SA, AD, VS and IS from plasma with acetonitrile. The total run time was 2.8 min and the elution of SA, AD, VS and IS occurred at 1.81, 1.12, 1.14 and 1.81 min, respectively; this was achieved with a mobile phase consisting of 0.02 m ammonium formate (pH 4.5):acetonitrile (20:80, v/v) at a flow rate of 0.50 mL/min on an X-Terra C18 column. A linear response function was established for the range of concentrations 0.5,50 ng/mL (r > 0.994) for VS and 0.2,50 ng/mL (r > 0.996) for SA and AD. The method validation parameters for all three analytes met the acceptance as per FDA guidelines. This novel method has been applied to human pharmacokinetic study. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Simultaneous determination of mycophenolic acid and valproic acid based on derivatization by high-performance liquid chromatography with fluorescence detection

BIOMEDICAL CHROMATOGRAPHY, Issue 4 2006
Yan Zhong
Abstract A reliable and validated reversed-phase high-performance liquid chromatography (HPLC) method using fluorescence detection is reported for the simultaneous quantitation of mycophenolic acid (MPA) and valproic acid (VPA) in human plasma. The method is based on the pre-column derivatization of valproic acid with 4-bromomethyl-6, 7-dimethoxycoumarin (BrMMC) and online solvatochromism of MPA by pH adjustment. The linear calibration range was 0.50,30 µg/mL for MPA and 5.00,150 µg/mL for VPA. The relative standard deviations of the method of intra- and inter-day analyses (n = 6) were below 6.5 and 6.7% for MPA, and 5.8 and 6.3% for VPA, respectively. Dichloromethane was used for the simultaneous extraction of MPA and VPA from acidified plasma. This reliable method can be applied in the analysis of MPA and VPA in human plasma using only a small volume (100 µL). Copyright © 2005 John Wiley & Sons, Ltd. [source]

Simultaneous determination of chlorpheniramine and pseudoephedrine in human plasma by liquid chromatography,tandem mass spectrometry

BIOMEDICAL CHROMATOGRAPHY, Issue 4 2004
Xiaoyan Chen
Abstract A sensitive and speci,c procedure for simultaneous quantitation of chlorpheniramine and pseudoephedrine in human plasma has been developed and validated. Analytes were extracted from plasma samples by liquid,liquid extraction, separated on a Diamonsil C18 column (250 × 4.6 mm i.d.) and detected by tandem mass spectrometry with an atmospheric pressure chemical ionization interface. Diphenhydramine was used as the internal standard. The method has a lower limit of quantitation of 0.2 and 2.0 ng/mL for chlorpheniramine and pseudoephedrine, respectively. The intra- and inter-day relative standard deviation, calculated from quality control (QC) samples were below 4.3% for chlorpheniramine and below 9.5% for pseudoephedrine. The inter-day relative error as determined from QC samples was within 4.7% for each analyte. The overall extraction recoveries of chlorpheniramine and pseudoephedrine were 77 and 61% on average, respectively. The method was successfully applied to pharmaockinetic study of chlorpheniramine and pseudoephedrine in volunteers receiving formulations containing 4 mg of chlorpheniramine maleate and 60 mg of pseudoephedrine hydrochloride. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Simultaneous determination of ondansetron and tropisetron in human plasma using HPLC with UV detection

BIOMEDICAL CHROMATOGRAPHY, Issue 3 2002
Steffen Bauer
A rapid and sensitve HPLC method for the simultaneous quantitation of ondansetron and tropisetron, two serotonin (5-HT) receptor antagonists frequently used in treatment and prevention of nausea and emesis, is described. The procedure involves liqid,liquid extraction of human plasma with dichloromethane coupled with reversed-phase HPLC and UV detection. The lower limits of quantification (LOQ) were 0.62,ng/mL for ondansetron and 1.25,ng/mL or tropisetron. Intra- and inter-assay coefficients of variation ranged from 1.5 to 7.5% and 5.3 to 13.7%, respectively. The sensitivity and precision were sufficient for determination of plasma concentrations after therapeutic administration of both drugs and the method can be used for the estimation of pharmacokinetic parameters. Copyright © 2002 John Wiley & Sons, Ltd. [source]