Enantiomer separation of amino acids and hydroxy acids by high performance liquid chromatography with chiral stationary phases

Enantiomer separation of amino acids and hydroxy acids by high performance liquid chromatography has been studied with three chiral stationary phases: [I] (S)-1-(α-naphthyl)ethyl amine, [II] N-(1R, 3R)- trans-chrysanthemoyl-D-phenylglycine, [III] N-t-butylaminocarbonyl-L-valine chemically bonded to 3- aminopropyl silica gel respectively. Various amino acid ester enantiomers were separated with good separation factors as N (O, S)-3, 5-dinitrobenzoyl derivatives on [I] and [II] except in the case of proline. Hydroxy acid ester enantiomers were not separated. in the form of 3, 5-dinitrobenzoyl derivatives, but separated in the form of 3, 5-dinitrophenylurethane derivatives on [I] and [III]. Proline ester enantiomers were also separated as N-3, 5-dinitrophenyl urea derivatives. These results show that the incorporation of the NH group may contribute effectively to the hydrogen bonding interaction with chiral stationary phases for the separation of enantiomers.