Determination of manidipine enantiomers in human serum using chiral chromatography and column-switching liquid chromatography.

A stereoselective and highly sensitive method using chiral chromatography and successive column-switching liquid chromatography is described for the determination of manidipine enantiomers in human serum. A human serum sample obtained after ingestion of manidipine was extracted twice with a mixture of n-hexane-diethyl ether under alkaline conditions. The enantiomers in the extract were separated on a chiral stationary phase column (Chiralcel OJ), and the effluents containing the respective enantiomers were collected. Each fraction was then analysed by column-switching liquid chromatography. The proposed stereoselective method offered high sensitivity: detection limits for both isomers were 0.2 ng/ml in human serum, both at a signal-to-noise ratio of 3. The method is suitable for the pharmacokinetic studies of manidipine enantiomers.