Enantiomeric resolution of amino acids by thin-layer chromatography

A simple and rapid method of separating optical isomers of amino acids on a reversed-phase TLC plate, without using impregnated plates or a chiral mobile phase, is described. Amino acids derivatized with 1-fluoro-2,4-dinitrophenyl-5-l-alanine amide were spotted on a reversed phase pre-coated TLC plate. Enantiomers of glutamate and aspartate were separated most effectively with solvent consisting of 25% acetonitrile in triethylamine-phosphate buffer (50 mM, pH 5.5) (v/v). Separation of l- and d-serine was achieved with 30% of acetonitrile solvent. The enantiomers of threonine, proline and alanine were separated with 35% of acetonitrile solvent, and those of methionine, valine, phenylalanine and leucine with 40% of acetonitrile solvent. The possibility of using TLC for quantitative determination of amino acid enantiomers was shown by the quantitative recovery of d- and l-alanine from the TLC plate in the range of 0.56–4.48 nmol.