Enantiomer separation of dihydropyridine calcium antagonists with cyclodextrins as chiral selectors: Structural correlation

Native and substituted cyclodextrins (CDs) were used as chiral selectors both in high-performance liquid chromatog raphy and capillary electromigration separations (HPCE and MEKC). Chromatographic data of five dihydropyridine calcium antagonists obtained on three beta-CD chiral stationary phases in reversed-phase mode were compared with those of capillary electrophoresis using beta-CDs in the presence and absence of sodium dodecyl sulfate (SDS). Competition of separated compounds with SDS molecules for penetration into the CD cavity can limit their necessary interaction with the chiral selector and consequently even preclude enantiomer separation. Some insight into this problem can be brought about by comparing the experimental data with computer-aided energy minimization of CD-solute and CD-SDS inclusion complexes.