Enantiometric separation of verapamil and norverapamil using Chiral-AGP as the stationary phase.

Simultaneous enantiomeric separation of verapamil and its main metabolite norverapamil was achieved using Chiral-AGP as the stationary phase. The optimized chromatographic system was obtained using statistical experimental design with partial least squares as regression method. The three variables studied were buffer pH, content of acetonitrile and column temperature. A high buffer pH favors enantioselectivity as well as the selectivity between (S)-verapamil and (R)-norverapamil. The concentration of the organic modifier in the mobile phase was a compromise as a high content of acetonitrile decreased enantioselectivity but increased the selectivity mentioned above. Increased column temperature increased the separation between (S)-verapamil and (R)-norverapamil with only a slight decrease in enantioresolution.