Fluorescence detection of Trace Dimethylamine and Diethylamine in Natural Water by HPLC with O-phthalaldehyde and 7-chlore-4nitrobenzo-2-oax-1, 3-diazole

A method of detecting dimethylamine (DMA) and diethylamine (DEA) was developed by HPLC with pre-column derivatization and fluorescence detection in this paper. Two fluorescent derivatization reagents were chosed to used in the method including o-phthalaldehyde (OPA) and 7-chlore-4-nitrobenzo-2-oax-1,3-diazole (NBD-Cl). Aliphatic amines in the natural water were labeled in two steps, the water samples were firstly reacted with OPA to eliminate aliphatic primary amines interferences, and then NBD-Cl could be used to selective detection of secondary amines, including dimethylamine and diethylamine. The detection limits of the method were 0.1 nmol/L and 10 nmol/L for DMA and DEA. Both of the linear ranges were 0.0005-0.1mol/mL with correlation coefficients above 0.9978 and 0.9988. This method is repeatable, sensitive and accurate for the detection of DMA and DEA in natural water samples.