LOW PICOGRAM DETERMINATION OF RO-48-6791 AND ITS MAJOR METABOLITE, RO-48-6792, IN PLASMA WITH COLUMN-SWITCHING MICROBORE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY COUPLED TO ION-SPRAY TANDEM MASS-SPECTROMETRY

A coupled liquid chromatography/tandem mass spectrometry assay was dev eloped for simultaneous determination of Ro 48-6791 and its secondary amine metabolite in human plasma samples with a quantification limit f or both compounds of 1 pg/mL using a 1 mL plasma aliquot. The method e xploits the enhanced mass sensitivity of a microbore (300 mu m i.d.) r eversed-phase capillary column coupled to an ion spray probe combined with tandem mass spectrometry. A straightforward column-switching syst em was utilized to focus the analytes onto a microbore trapping column following solid-phase extraction of a 50 mu L plasma sample extract f rom liquid/liquid extraction. Backflushing of the retained analytes fr om the trapping column onto the microbore capillary column provided th e requisite high peak concentration for high sensitivity. The inter-as say precision and accuracy for Ro 48-6791 and its metabolite, at 10 pg /mL, were found to be 3.4%, and 105%, and 9.1%, and 99.9%, respectivel y. The calibration curves were linear over the range 1 to 1000 pg/mL. The method proved to be sufficiently rugged for analysis of samples. ( C) 1997 by John Wiley & Sons, Ltd.