Simultaneous determination of Ziagen and its phosphorylated metabolites byion-pairing high-performance liquid chromatography-tandem mass spectrometry

An ion-paring HPLC-MS-MS method with positive ion mode electrospray ionizat ion has been developed to simultaneously quantify Ziagen, carbovir monophos phate, carbovir diphosphate and carbovir triphosphate. N',N'-Dimethylhexyla mine was used as the ion-pairing agent. The presence of this ion-pairing ag ent allowed the retention and separation of the four compounds on a reverse d-phase HPLC column as well as the detection of the nucleotides with positi ve ion mode electrospray ionization. The limits of detection were found to be better than 25 nM for all the analytes. Calibration curves of the analyt es showed excellent linearity over the range of 25 nM to 5 muM. The relativ e standard deviations and accuracies for replicate analyses of quality cont rol samples were less than 15%. The method has been successfully applied to the analysis of these compounds in human liver cells treated with Ziagen. (C) 2001 Elsevier Science B.V. All rights reserved.