Enantiomeric and diastereomeric high-performance liquid chromatographic separation of cyclic beta-substituted alpha-amino acids on a teicoplanin chiral stationary phase

High-performance liquid chromatographic (HPLC) separation of stereomeric cy clic beta-substituted alpha-quaternary alpha-amino acids was performed on a chiral stationary phase based on the glycopeptide antibiotic teicoplanin. The investigated amino acids are the 1-amino-2-methylcyclohexanecarboxylic acids, the l-amino-2-hydroxycyclohexanecarboxylic acids, Ala, Cha, Phe and Tie. The effects of the mobile phase composition (type and content of organ ic modifier, pH) and of the temperature on the enantio- and diastereoselect ivity were studied and the conditions were optimised to resolve the four st ereomers of one amino acid in a single chromatographic run. The influence o f the modifier concentration and the pH of the mobile phase reveal two enan tiomeric and diastereomeric discrimination mechanisms based on different in teractions with the stationary phase. For optimal separation of diastereome rs the column has to be conditioned with an acidic eluent. (C) 2000 Elsevie r Science B.V. All rights reserved.