Original PaperApplication of 10-ethyl-acridine-3-sulfonyl chloride for HPLC determination of aliphatic amines in environmental water using fluorescence and APCI-MS A simple, sensitive method for the determination of aliphatic amines based on a sulfonylation reaction using 10-ethyl-acridine-3-sulfonyl chloride (EASC) as pre-column labeling reagent with fluorescence detection and APCI-MS identification has been developed. The labeled derivatives exhibited high stability and were enough to be efficiently analyzed by HPLC with an excitation maximum at k ex 270 nm and an emission maximum at k em 430 nm. Identification of derivatives was carried out by online post-column MS in positive-ion mode. Comparing with the widely used 5-dimethylaminonaphthalene-1-sulfonylchloride (Dansyl-Cl), EASC-amine derivatives not only exhibited high fluorescence but also exhibited excellent MS ionizable potential. Detection limits obtained from 0.10 pmol injection, at a S/N of 3, were 4.0 -12.7 fmol. The mean intra-and inter-assay precision for all aliphatic amine levels were a3.84 and 3.21%, respectively. Excellent linear responses were observed with coefficients of A0.9995.