SEPARATION AND DETERMINATION OF WARFARIN ENANTIOMERS IN HUMAN PLASMA SAMPLES BY CAPILLARY ZONE ELECTROPHORESIS USING A METHYLATED BETA-CYCLODEXTRIN-CONTAINING ELECTROLYTE

A methyl beta-cyclodextrin with a degree of substitution of 1.8 proved to be an effective chiral selector, among other cyclodextrins tested, for the separation of warfarin enantiomers by capillary electrophores is. The operating conditions were optimized with respect to electrolyt e composition (buffer pH, ionic strength, cyclodextrin concentration, methanol content) and applied voltage. The influence of a high ionic s trength on the resolution was clearly shown. A baseline separation can be obtained in less than 15 min with an efficiency of ca. 250 000 the oretical plates. These conditions were applied to the determination of warfarin enantiomers in the plasma of patients under warfarin therapy . The limit of detection for the whole procedure (dichloromethane extr action followed by evaporation to dryness and capillary electrophoresi s) was of the order of 0.2 mg/l (6.5 - 10(-7) M) of each enantiomer.