Enantiomeric separation of non-protein amino acids by chiral ligand-exchange high-performance liquid chromatography

The enantiomeric separation by high-performance liquid chromatography 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). Excellent to good separations of enantiomers were achieved with a variety of non-protein amino acids carrying aliphatic or aromatic side-chains by optimizing the amount (0 - 20%, v/v) of the organic component (2-propanol) and the concentration (1 - 5 mM) of the complexing metal ion (Cu2+) in the hydro-organic eluent.