Effect of mobile phase composition on the separation of propranolol enantiomers using a perphenylcarbamate beta-cyclodextrin bonded chiral stationary phase.

An analytical column packed with a novel perphenylcarbamate beta-cyclodextrin bonded chiral stationary phase was used to separate propranolol enantiomers. Good separation results were obtained using triethylammonium acetate (TEAA) buffer and methanol mixtures as the mobile phase. Effects of the methanol concentration, buffer concentration and pH value on the retention and the enantioselectivity of propranolol enantiomers were investigated on this column. The retention times and the separation factor decrease with increase of the methanol concentration as expected in reversed-phase HPLC. At trace TEAA amount, the solute eluted out with anti-Langmuirian band profiles, their retention times decreased quickly with increase of TEAA concentration and attained a minimum at a TEAA concentration of 20 ppm. Above 20 ppm, solute band profiles changed to a Langmuirian shape, the retention times of enantiomers increased with increasing buffer concentration, and eventually, they attained asymptotes at ca. 1% TEAA. A simulation considering the different interactions between the solute and the additive at above and below 20 ppm TEAA concentration as well as system peaks interference can successfully explain the anti-Langmuirian band profiles and the retention time variation trend.