Abstract

Background: A microdose study was performed where 50 μg R/S- 14C-verapamil was dosed intravenously to human volunteers. In order to quantify the individual R- and S-enantiomers in human plasma a 2D chiral HPLC method with subsequent analysis by accelerator mass spectrometry was verified. Results: R/S-verapamil was separated on a C18 column and the isolated fraction was applied to a chiral column where the verapamil enantiomers were separated. Experimental recovery (�73 coefficient of variation {CV} = 16% and 66% CV = 21% for R- and S-verapamil, respectively) was accounted for by the use of internal standardization from the fluorescence response of nonlabeled R- and S-verapamil. The precision of the assay ranged from 4.1 to 15.9% CV and the limit of quantitation was 1.95-4.81 pg/ml for R-verapamil and 1.76-3.34 pg/ml for S-verapamil. Conclusion: This method was successfully applied to the analysis of R- and S-verapamil in human plasma. © 2010 Future Science Ltd.