A versatile system of high-flow high performance liquid chromatography with tandem mass spectrometry for rapid direct-injection analysis of plasma samples for quantitation of a beta-lactam drug candidate and its open-ring biotransformation product

A bioanalytical method has been developed and validated for quantitation of a beta-lactam drug candidate and its open-ring biotransformation product u tilizing high-how high-performance liquid chromatography (HPLC) for on-line purification of plasma samples and electrospray tandem mass spectrometry f or detection and quantitation. The HPLC system used two columns: an Oasis c olumn (1 x 50 mm, 30 mu m) as the on-line extraction column and a conventio nal C18 column (2 x 50 mm, 5 mu m) as the analytical column. Each plasma st andard or quality control (QC) sample (50 mu L) was mixed with 50 mu L of a working solution of the internal standard in aqueous 0.5 M ammonium acetat e (pH 4.0), Portions (10 mu L) of these samples were then injected into an Oasis column with a mobile phase consisting of 100% aqueous 1 mM formic aci d at a high flow rate (4.0 mL/min), with the effluent from the Basis column directed to waste and not to the mass spectrometer. After the purification step, the Oasis column effluent was directed to the analytical column and the mass spectrometer and the analytes were eluted with methanol/aqueous I mM formic acid (70:30) at a how rate of 1.0 mL/min, The total analysis time was 1.6 min per sample. The standard curve range was 0.980 to 250 ng/mL. T he accuracy, inter-day precision and intra-day precision were within 10% fo r both compounds. Copyright (C) 1999 John Whey & Sons, Ltd.