Stereoselective quantitation of a serine protease inhibitor using LC-MS/MS at elevated column temperature.

A LC-MS/MS method using a LC column packed with sub-2 micron particles and elevated column temperatures was validated for the quantitation of SCH 503034 diastereomers (SCH 534128 and SCH 534129) in human plasma. The method was validated over the concentration range of 2.5 to 1250 ng/mL.

Simultaneous determination of desloratadine and pseudoephedrine in human plasma using micro solid-phase extraction tips and aqueous normal-phase liquid chromatography/tandem mass spectrometry.

Cation-exchange micro solid-phase extraction (SPE) tips and aqueous normal-phase (ANP) chromatography coupled with tandem mass spectrometry were explored for the rapid, selective and sensitive quantitation of desloratadine and pseudoephedrine in human plasma. A novel micro-SPE device was evaluated for analyte capacity, extraction efficiency and its ability to maximize recovery of an analyte of interest from bioanalytical matrices by successive replicates of linked extraction steps. Ion suppression using two different methods with micro-SPE tips was negligible when compared to protein precipitation.