Adsorption liquid chromatography on silica for the chiral separation of amino acids and asymmetric amines derivatized with optically active N-alpha-9-fluorenylmethyloxycarbonyl-amino acid-N-carboxyanhydrides

Optically pure N-alpha-Fmoc-amino acid-N-carboxyanhydrides (Fmoc-AA-NCAs, Fmoc=9-fluorenylmethyloxycarbonyl) are proposed as precolumn reagents for the chiral analysis of asymmetric amines including alpha-amino acid alkyl esters. Separation of diastereomers arising from racemic amines is better achieved by liquid-solid adsorption chromatography on silica than by reversed-phase techniques. The sample preparation is easily performed while the properties of the Fmoc group allows high sensitivity by fluorescent detection. In this mode, picomolar limits of enantiomeric excess are detected.