Simultaneous determination of irbesartan and hydrochlorothiazide in human plasma using HPLC coupled with tandem mass spectrometry: Application to bioequivalence studies.

A sensitive, specific and selective liquid chromatography/tandem mass spectrometric method has been developed and validated for the simultaneous determination of irbesartan and hydrochlorothiazide in human plasma. Plasma samples were prepared using protein precipitation with acetonitrile, the two analytes and the internal standard losartan were separated on a reverse phase C(18) column (50mmx4mm, 3microm) using water with 2.5% formic acid, methanol and acetonitrile (40:45:15, v/v/v (%)) as a mobile phase (flow rate of 0.

Simultaneous determination of bisoprolol and hydrochlorothiazide in human plasma by HPLC coupled with tandem mass spectrometry.

A sensitive, specific and selective method has been developed for the simultaneous determination of bisoprolol and hydrochlorothiazide in human plasma. The method employed a state of the art LC-MS/MS operated in the positive and negative ionization switching modes. A simple sample preparation step involving protein precipitation with acetonitrile has been optimized; the analytes and the internal standard moxifloxacin were separated on a Purosphere STAR C8 column (125 mm x 4 mm, 5 microm).

Reactions of sulfenic acid with 2-mercaptoethanol: a mechanism for the inhibition of gastric (H+-K+)-adenosine triphosphate by omeprazole.

The reactions of omeprazole, a potent proton pump inhibitor (PPI) were investigated in the presence of 2-mercapotoethanol. Reactions were monitored in solutions buffered to pH values ranging 2.0-8.

Acid decomposition of omeprazole in the absence of thiol: a differential pulse polarographic study at the static mercury drop electrode (SMDE).

The reactions of omeprazole, a potent proton pump inhibitor (PPI), were investigated in the absence of a nucleophile. Reactions were monitored, using differential pulse polarography (DPP) at the static mercury drop electrode (SMDE), in solutions buffered to pH values ranging from 2.0 to 8.