Separation of Enantiomers of Non-Protein Amino Acids by High-Performance Liquid Chromatography on a Chiral Ligand-Exchange Column

The HPLC separation of enantiomers of underivatized non-protein amino acids was investigated by using a column packed with octadecylsilanized silica coated with N,S-dioctyl-D-penicillamine as a chiral ligand-exchange phase (Sumichiral OA-5000). Good enantiomeric separations were achieved with a variety of -amino acids carrying aliphatic or aromatic side chains, cyclic imino acids, and -amino acids, together with -methyl--amino acids, by optimizing the amount (0–20%, v/v) of 2-propanol as the organic component and the concentration (1–5 mM) of Cu²⁺ as the complexing metal ion in the aqueous-organic eluent.