DETERMINATION OF CYTOSINE-BETA-D-ARABINOSIDE IN PLASMA USING CAPILLARY ELECTROPHORESIS

An assay for the antileukaemic agent cytosine-beta-D-arabinoside (ara-C) has been developed using capillary zone electrophoresis. Solid-phase extraction and on-capillary peak concentration are used to improve the detection limit. The electrophoretic separation time is less than 5 min. The limit of detection for ara-C in plasma is 0.5-mu-M (signal-to-noise ratio = 3). The assay has been validated for the determination of ara-C in human plasma over the concentration range 1-10-mu-M. The calibration curve was linear with a correlation coefficient r2 = 0.996. At an ara-C concentration of 8-mu-M the intra-day coefficient of variation was 9.1% and the inter-day coefficient of variation was 12.3%. At an ara-C concentration of 2-mu-M the coefficients of variation were 15.2 and 12.0%, respectively.