Determination of Free Aliphatic Amines in Environmental Water by EASC Derivatization and Identification with LC-APCI-MS

On a reversed-phase Hypersil BDS C-18 (4.6 mm x 200 mm, 10 mu m i.d.) column, 12 aliphatic amines were derivatized using 10-ethyl-9-oxo-9,10-dihydroacriditie-2-sulfonyl chloride(EASC) as a new pre-column derivatization reagent. The complete baseline resolution was obtained in conjunction with a gradient elution with acetonitrile/H2O as mobile phase within 20 min. The optimum excitation and emission wavelengths were at lambda(ex)/lambda(em) = 270 nm/430 nm. Comparing with the widely used Dansyl-Cl, EASC has stronger photoluminescence characteristics(ultraviolet and fluorescence) : UVEASC/UVDansyl-Cl = 3.2 (UV: ultraviolet absorption intensity); I(EASC/I(Dansyl-Cl) = 30.0: 1-105. 4:1 (I: relative fluorescence intensity); fluorescence quantum yield: Phi(f)(EASC)/Phi(f)(Dansyl-Cl) = 43.0:1. Fast and accurate quantitative analysis of aliphatic amines with fluorescence and corresponding post-column ion trap mass spectrometry(LC-APCI-MS) were obtained. EASC-amines exhibited stronger mass spectrometric sensitivity relative to that of dansyl-amine derivatives: MSEASC/MSDansyl-Cl = 1. 6: 1-6. 2: 1 times(MS: relative intensity of ion current). The established method for the determination of aliphatic amines in environmental water samples exhibited good reproducibility and recovery. Excellent linear responses were observed with the correlation coefficients >0.9995. The detection limits(at signal-to-noise of 3: 1) were at levels of 4.0-12.7 fmol.