Capillary electrophoresis-ion trap mass spectrometry analysis of Ziagen® and its phosphorylated metabolites

A capillary electrophoresis-ion trap mass spectrometry method with a time-segment program was developed to simultaneously analyze Ziagen® and its phosphorylated metabolites such as carbovir monophosphate, carbovir diphosphate, and carbovir triphosphate. By using the time-segment program, the positively charged nucleoside analog and negatively charged nucleotides were separated and detected in a single electrophoretic run. The limits of detection were less than 2 μM for all of the analytes. Calibration curves of the compounds showed excellent linearity over the range of 2-100 μM. The capability of the method was demonstrated by analyzing Ziagen® and its phosphorylated metabolites that were spiked in cellular extracts of human peripheral blood mononuclear cells at 20 μM levels. Some endogenous nucleotides such as adenosine 5′-triphosphate, adenosine 5′-diphosphate, and adenosine 5′-monophosphate, were also detected in the cellular extracts.