Chiral separation of enantiomers of substituted alpha- and beta-alanine and gamma-aminobutyric acid analogues by gas chromatography and high-performance liquid chromatography.

Gas chromatography (GC) with a chiral stationary phase, Chirasil-Val, has been used for separation of the enantiomers of several analogues of alpha- and beta-alanine as their N-trifluoroacetyl isopropyl esters. The same chiral phase GC procedure has been applied to the enantiomeric separation of various substituted gamma-aminobutyric acid analogues (GABA). Reversed-phase high-performance liquid chromatography (HPLC) with the chiral copper-L-proline complex allowed a clear resolution of all the alpha-amino acids in their underivatized forms. It yielded somewhat smaller separation coefficients for the substituted beta-alanines and no resolution for the GABA analogues. The influence of the nature of the amino acid, alpha, beta or gamma, and the effects of the different substituents on the separation coefficients obtained by GC and HPLC are discussed.