Enantioselective assay of warfarin in blood plasma by liquid chromatography on Chiralcel OC.

A stereoselective method for the two enantiomers of warfarin has been developed. Warfarin is extracted into dichloromethane-hexane from blood plasma. After concentration by evaporation, the enantiomers are resolved by liquid chromatography on Chiralcel OC employing a non-polar mobile phase. By fluorometric detection, concentrations in plasma down to 80 nmol/l (25 ng/ml) can be determined with a coefficient of variation of less than 15%. At the 200 nmol/l level, a coefficient of variation of ca. 4% was found.