Quantification of daunorubicin and daunorubicinol in plasma by capillary electrophoresis

Capillary electrophoresis (CE) with laser-induced fluorescence detection was applied to quantify daunorubicin and daunorubicinol in plasma. Separation was carried out in a 47 cm×50 μm I.D. fused-silica capillary, with a running buffer, pH 5 containing 60 μM spermine and 70% acetonitrile. Sample preparation was done either by protein precipitation with acetonitrile or by liquid–liquid extraction. The assay can be applied in a concentration range from 40 mg/l down to 2 μg/l for daunorubicin and from 1 mg/l to 2 μg/l for daunorubicinol. Precision and accuracy were between 2.9 and 14.5% (n=6) on 1 day and between 1.0 and 14.7% from day to day (n=6) for both analytes. Thus, the CE method enables precise and accurate quantification of daunorubicin and daunorubicinol in small sample volumes over a wide concentration range.