A combined method of immunoaffinity extraction with high-performance liquid chromatography has been developed for the enantioselective determination of bufuralol and its metabolites in human plasma. The antibodies having high affinity toward the asymmetric center at the C-1 position of bufuralol and its 1'-oxidized metabolites and low affinity to their antipodes were elicited by immunization of rabbits with immunogens, (1R)- and (1S)-1'-oxobufuralol O-carboxymethyloxime-bovine serum albumin conjugates, respectively. 0.5 ml of the immunoaffinity adsorbent (7.6 mg · ml-1 for anti-(1S)-antibody and 28.8 mg · ml-1 for anti-(1R)-antibody) prepared by immobilization of an antibody was capable of retaining up to 1 μg of (R)- and (S)-bufuralol and up to 500 ng of other metabolites. The adsorbates were recovered quantitatively by elution with methanol-10 mM ammonium acetate buffer (pH 5) (95:5, v/v) without any interfering peaks on the high-performance liquid chromatogram. The proposed method was evaluated to be useful for the simultaneous determination of optically active bufuralol and its metabolite in plasma with acceptable recovery and precision.
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