Separation of benzoxazine enantiomers on β-cyclodextrin bonded chiral stationary phases

Chiral separation of benzoxazine enantiomers was studied on click chemistry based beta-cyclodextrin stationary phases under reversed-phase high performance liquid chromatographic mode. The effects of the type and percentage of the organic modifier, the concentration of triethylammonium acetate buffer (TEAA), and pH on enantioselective separation were examined and studied. It was demonstrated that acetonitrile was better for the chiral separation of benzoxazine enantiomers than methanol. It was observed that the retention time and the resolution of benzoxazine enantiomers decreased with the increase of the volume ratio of TEAA from 0.1% to 1.0%. The separation of benzoxazine enantiomers was of the maximum resolution at pH 4.1. With the optimized mobile phase of the mixture of acetonitrile and 0. 1% TEAA (pH 4.1), all the enantiomers were separated at the baseline. The chiral recognition mechanism is also discussed. The separation was probably based on the inclusion complex interaction and the hydrogen bonding between enantiomers and chiral stationary phases. This work provided the experience for the intensive study of click beta-cyclodextrin bonded stationary phases, and it also illustrated the potential of click chemistry in the preparation of beta-cyclodextrin based chiral stationary phase.