4-N,N-Dimethylaminosulfonyl-7-N-(2-aminoethyl)amino-benzofurazan as a new precolumn fluorescence derivatization reagent for carboxylic acids (fatty acids and drugs containing a carboxyl moiety) in liquid chromatography

A new fluorescent reagent for carboxylic acids, 4-N,N-dimethylaminosulfonyl-7-N-(2-aminoethyl)amino-2,1,3-benz oxadiazole (DBD-ED) was synthesized from 4-N,N-dimethylaminosulfonyl-7-chloro-2,1,3-benzoxadiazole (DBD-Cl) and 1,2-diaminoethane. DBD-Cl is also a new compound described in this work for the first time. The applicability of DBD-ED as a precolumn derivatization reagent in liquid chromatography (LC) was examined. DBD-ED reacted with saturated fatty acids and non-steroidal anti-inflammatory drugs (NSAIDs) in the presence of triphenylphosphine and 2,2'-dipyridyl disulfide at room temperature for 30 min for NSAIDs and 1 h for fatty acids to give fluorescent products. The reaction solutions were subjected to LC and the derivatized products were detected spectrofluorimetrically at 560 nm with excitation at 450 nm. The detection limits were in the fmol range.