RESOLUTION AND SENSITIVE DETECTION OF CARBOXYLIC-ACID ENANTIOMERS USING FLUORESCENT CHIRAL DERIVATIZATION REAGENTS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Chiral derivatization reagents possessing a dansyl (N-dimethylaminoaph thalene-5-sulphonyl) moiety as fluorophore were developed for the sepa ration and sensitive detection of carboxylic acid enantiomers by high- performance liquid chromatography (HPLC). Synthesis of d- and l-1-(4-d ansylaminophenyl)ethylamine (DAPEA) from easily obtained starting mate rials by simple four-step reactions gave satisfactory yields. The reag ents reacted with carboxylic acid enantiomers such as anti-inflammator y drugs in the presence of condensing agents (2,2'-dipyridyl disulphid e and triphenylphosphine) at room temperature for 2.5 h to give corres ponding diastereomeric amide derivatives quantitatively. The fluoresce nce characteristics of the amide formed from DAPEA with 2-phenylpropio nic acid enantiomer (DAPE-PPA) were hardly affected by the pH and wate r content of the mobile phase in the range commonly used for reversed- phase HPLC. The diastereomeric pairs formed from five anti-inflammator y drugs and phenylpropionic acid with DAPEA were efficiently separated by reversed-phase HPLC. The detection limit (signal-to-noise ratio = 3) of DAPE-PPA, when the resulting derivatization reaction mixture was directly injected on to the column, was 170 fmol per injection.