Home  About us  Contact
 

Interface Operating (interface + operating)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Simultaneous determination of simvastatin and simvastatin acid in human plasma by LC-MS/MS without polarity switch: Application to a bioequivalence study

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2008
Bhavin N. Patel
Abstract A simple, specific and sensitive LC-MS/MS assay for simultaneous determination of simvastatin (SV) and its active ,-hydroxy acid metabolite, simvastatin acid (SVA) in human plasma was developed using a statin analog as internal standard (IS). The method was validated over a dynamic linear range of 0.20,100.00 ng/mL for SV and 0.10,50.00 ng/mL for SVA with correlation coefficient r , 0.9987 and 0.9989, respectively. The analytes and IS were extracted from 500 ,L aliquots of human plasma via liquid-liquid extraction using methyl tert -butyl ether and separated through an Aquasil C18 column (100 mm×2.1 mm, 5 ,m). Detection of analytes and IS was done by MS/MS with a turbo ion spray interface operating in positive ion and selective reaction monitoring acquisition mode. The total chromatographic run time was 3.0 min. Flash freezing of the aqueous phase was an added advantage during liquid-liquid extraction, which considerably reduced time and labour. The method was extensively validated for its accuracy, precision, recovery, stability studies and matrix effect. The method was successfully used for bioequivalence study of 40 mg SV tablet formulation in 12 human subjects under fasting condition. [source]

High-performance liquid chromatography and LC-ESI-MS method for identification and quantification of two isomeric polyisoprenylated benzophenones isoxanthochymol and camboginol in different extracts of Garcinia species

BIOMEDICAL CHROMATOGRAPHY, Issue 8 2009
Satyanshu Kumar
Abstract A rapid, sensitive and simple reverse-phase high-performance liquid chromatography,electrospray ionization mass spectrometric method has been developed for the identification and quantification of two isomeric polyisoprenylated benzophenones, isoxanthochymol and camboginol, in the extracts of the stem bark, seeds and seed pericarps of Garcinia indica and in the fruit rinds of Garcinia cambogia. The separation of isoxanthochymol and camboginol was achieved on a Perkin Elmer RP8 column (10 × 2.1 mm with 5.0 µm particle size) using a solvent system consisting of a mixture of acetonitrile,water (80:20, v/v) and methanol,acetic acid (99.0:1.0, v/v) as a mobile phase in a gradient elution mode. The limits of detection and quantification were 5 and 10 µg/mL for isoxanthochymol and 50 and 100 µg/mL for camboginol, respectively. The intra- and inter-day precisions were 2.34 and 3.41% for isoxanthochymol and 3.35 and 3.66% for camboginol. The identity of the two isomeric compounds in the samples was determined on a triple quadrupole mass spectrometer with ESI interface operating in the negative ion mode. The method was used to identify and quantify isoxanthochymol and camboginol in the different extracts of two Garcinia species, Garcinia indica and Garcinia cambogia. Copyright © 2009 John Wiley & Sons, Ltd. [source]

High-performance liquid chromatography and LC-ESI-MS method for the identification and quantification of two biologically active isomeric coumarinolignoids cleomiscosin A and cleomiscosin B in different extracts of Cleome viscosa

BIOMEDICAL CHROMATOGRAPHY, Issue 12 2008
Sunil K. Chattopadhyay
Abstract A rapid, sensitive and simple reverse-phase high-performance liquid chromatographic,electrospray ionization,mass spectrometry method for simultaneous determination of cleomiscosin A and cleomiscosin B has been developed and validated. The isomeric coumarinolignoids cleomiscosin A (1) and cleomiscosin B (2) were separated on a Waters symmetry C18 column with a solvent system composed of acetonitrile,methanol (1:2) and acetic acid,water (0.5 : 99.5) in a gradient elution mode. The absorption at 326 nm was chosen as the measuring wavelength in which resolution and baseline separation of compounds 1 and 2 could be obtained. The identity of the two isomeric compounds 1 and 2 in the samples were determined on a triple quadrupole mass spectrometer with ESI interface operating in the positive mode. Calibration curves were linear (r2 > 0.993) over the concentration range 20,200 µg/mL for cleomiscosin A and 10,200 µg/mL for cleomiscosin B with acceptable accuracy and precision, respectively. The intra-day and inter-day precision were 1.13 and 0.82% for cleomiscosin A and 1.78 and 1.28% for cleomiscosin B, respectively. The validated method was successfully applied for the analysis of the above two compounds in different extracts of Cleome viscosa. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Rapid quantification of lisinopril in human plasma by liquid chromatography/tandem mass spectrometry

BIOMEDICAL CHROMATOGRAPHY, Issue 4 2007
Weiwei Qin
Abstract An assay based on protein precipitation and liquid chromatography/tandem mass spectrometry (LC-MS/MS) has been developed and validated for the quantitative analysis of lisinopril in human plasma. After the addition of enalaprilat as internal standard (IS), plasma samples were prepared by one-step protein precipitation using perchloric acid followed by an isocratic elution with 10 mm ammonium acetate buffer (pH adjusted to 5.0 with acetic acid),methanol (70:30, v/v) on a Phenomenex Luna 5µC18 (2) column. Detection was performed on a triple-quadrupole mass spectrometer utilizing an electrospray ionization (ESI) interface operating in positive ion and selected reaction monitoring (SRM) mode with the precursor to product ion transitions m/z 406,246 for lisinopril and m/z 349,206 for enalaprilat. Calibration curves of lisinopril in human plasma were linear (r = 0.9973,0.9998) over the concentration range 2,200 ng/mL with acceptable accuracy and precision. The limit of detection and lower limit of quantification in human plasma were 1 and 2 ng/mL, respectively. The validated LC-MS/MS method has been successfully applied to a preliminary pharmacokinetic study of lisinopril in Chinese healthy male volunteers. Copyright © 2007 John Wiley & Sons, Ltd. [source]