Abstract
Enantiomeric separation of underivatized amino acids using N-alkyl-L-proline (octyl, dodecyl or hexadecyl) coated HPLC has been accomplished. The anchoring N-alkyl groups of L-proline provides a permanent adsorption of there solving chiral agent on the hydrophobic interface layer of a reversed phase. The factors controlling retention and enantioselectivity such as the Cu(II) concentration, pH of the eluent, the type and concentration of organic modifier in the hydroorganic eluent, and extent of coating were examined. The elution orders between D- and L-amino acids were consistent, L-forms eluting first, except histidine and asparagine. The extremely high enantioselectivity $(\alpha$ upto 13 for proline) is observed. The retention mechanism for the chiral separation can be illustrated by a complexation and hydrophobic interaction.