A rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS)assay method has been developed and fully validated for the simultaneous quantification of pravastatin and aspirin in human plasma.Furosemide was used as an internal standard.Analytes and the internal standard were extracted from human plasma by liquid-liquid extraction technique using methyl tertiary butyl ether.The reconstituted samples were chromatographed on a Zorbax SB-C18 column by using a mixture of 5 mM ammonium acetate buffer and acetonitrile (20∶80,v/v) as the mobile phase at a flow rate of 0.8 mL/min.The calibration curve obtained was linear (r(≥)0.99)over the concentration range of 0.50-600.29 ng/mL for pravastatin and 20.07-2012.00 ng/mL for aspirin.Method validation was performed as per FDA guidelines and the results met the acceptance criteria.A run time of 2.0 min for each sample made it possible to analyze more than 400 human plasma samples per day.The proposed method was found to be applicable to clinical studies.

An analytical method based on ultra-performance liquid chromatography with positive ion electrospray ionization (ESI) coupled with tandem mass spectrometry (UPLC–MS/MS) was developed and validated for the determination of therapeutic peptide desmopressin in human plasma. A desmopressin stable labeled isotope (desmopressin d8) was used as an internal standard. Analyte and the internal standard were extracted from 200 μL of human plasma via solid-phase extraction technique using Oasis WCX cartridges. The chromatographic separation was achieved on an Aquity UPLC HSS T3 column by using a gradient mixture of methanol and 1 mM ammonium formate buffer as the mobile phase. The calibration curve obtained was linear (r2≥0.99) over the concentration range of 1.01–200 pg/mL. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. The proposed method was successfully applied to pharmacokinetic studies in humans.

A simple and rapid liquid chromatography-tandem mass spectrometric (LC-MS/MS)assay method has been developed and fully validated for simultaneous quantification of pioglitazone and candesartan in human plasma.Irbesartan was used as an internal standard.The analytes were extracted from human plasma samples by solid-phase extraction technique using a Strata-X 33 μm polymeric sorbent.The reconstituted samples were chromatographed on a C18column by using a 80∶20 (v/v) mixture of acetonitrile and 0.1％ formic acid as the mobile phase at a flow rate of 0.8 mL/min.The calibration curves obtained were linear (r(≥)0.99) over the concentration range of 15-3000 ng/mL for pioglitazone and 5-608 ng/mL for candesartan.The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits.A run time of 2.7 min for each sample made it possible to analyze more than 300 plasma samples per day.The proposed method was found to be applicable to clinical studies.