Direct chiral separation of unnatural amino acids by high-performance liquid chromatography on a ristocetin A-bonded stationary phase

Direct high-performance liquid chromatographic chiral separation of numerou s underivatized unnatural amino acids on a ristocetin A-bonded chiral stati onary phase used in the reversed-phase and in the polar organic chromatogra phic modes is reported. The effects of different parameters such as mobile phase composition, temperature, and the structure of the analytes on the se lectivity in both chromatographic modes are discussed. By variation of the, parameters, the separation of the stereoisomers was optimized and,. as a r esult baseline resolution was achieved in most cases. (C) 2001 Wiley-Liss, Inc.