HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC SEPARATION OF ONDANSETRON ENANTIOMERS IN SERUM USING A CELLULOSE-DERIVATIZED STATIONARY-PHASE AND SOLID-PHASE EXTRACTION

R(-)-Ondansetron and S(+)-ondansetron in human serum were resolved and quantified using a stereospecific HPLC method. Each enantiomer and th e internal standard prazosin were isolated from serum using a solid-ph ase extraction procedure on a cyanopropyl column. Recoveries of 97, 96 and 88% were obtained for the R(-)-enantiomer, the S(+)-enantiomer, a nd the internal standard, respectively. A cellulose-based chiral analy tical column (Chiralcel OD) was used with a mobile phase consisting of hexane-95% ethanol-2-propanol-acetonitrile (65:25:10:1, v/v). Linear calibration curves were obtained for each enantiomer in serum in the c oncentration range 10-200 ng/ml. The limit of quantitation of each ena ntiomer was 10 ng/ml. The detection limit for each enantiomer in serum using UV detection at 216 nm was 2.5 ng/ml (signal-to-noise ratio of 3).