A new rapid and economical high performance liquid chromatographic assay with electrochemical detection for the determination of etoposide (VP-16) in human plasma samples

A high performance liquid chromatographic assay with electrochemical detection has been developed for the determination of etoposide in human plasma samples. 2-acetamidophenol was used as internal standard and extraction was performed with ethyl ether-dichloromethane (2:1) in a single step. Analyses were carried out on a Nova Pak C₈ column using methanol-75 mM acetate buffer (45:55) as mobile phase. The effluent from the column was monitorized at +800 mV against Ag/AgCl and the resulting current was registered. The assay was linear within the range of 0.02-4 μg/mL, coefficients of variation being lower than 10%. Detection limit was 5 ng/mL. The method is rapid and economical. Therefore, it is suitable for routine monitoring of etoposide pharmacokinetics after administration of low oral doses according to recent therapeutic schemes.