Analysis of the band profiles of the enantiomers of phenylglycine in liquid chromatography on bonded teicoplanin columns using the stochastic theory of chromatography

The retention behaviour of the enantiomers of underivatized phenylglycine w as studied on a Chirobiotic T column packed with amphoteric glycopeptide te icoplanin covalently bonded to the surface of silica gel. The retention and the selectivity of separation of the enantiomers increase with rising conc entration of ethanol or of methanol in aqueous-organic mobile phases. The b and profiles of the less retained L-phenylglycine are symmetrical, but the band profiles of the more strongly retained D-phenylglycine are tailing in all mobile phases tested. The band broadening does not diminish even at ver y low concentrations of phenylglycine, so that it cannot be attributed to p ossible column overload. The analysis of the band profile using the stochas tic theory of chromatography suggests that the broadening can be attributed to at least two additional chiral centres of adsorption in the stationary phase contributing to the retention of the more strongly retained enantiome r in addition to the adsorption of the less retained one. This behaviour ca n be explained by the complex structure of the teicoplanin chiral stationar y phase. (C) 2001 Elsevier Science B.V. All rights reserved.