Determination of the enantiomers of verapamil and norverapamil in serum using coupled achiral-chiral high-performance liquid chromatography

An assay for the plasma concentration of the enantiomers of verapamil and its metabolite norverapamil has been developed using the improved version of the α1-acid glycoprotein chiral stationary phase (CHIRAL AGP-CSP) coupled to a shielded hydrophobic phase (Hisep)_column. The Hisep column was used to separate verapamil and norverapamil from the plasma components and from each other and to quantitate the total verapamil and norverapamil concentrations. The eluents containing verapamil and norverapamil are then selectivity transfered to the CHIRAL AGP-CSP where the enantiomers were stereochemically resolved and the enantiomeric composition determined. The system is the first reported for the serum concentration of the enantiomers of verapamil after the clinical administration of the drug and the first to sterochemically resolve and quatitate the enantiomers of norverapamil.