N-nitrosomethylethylamine (nmea) and N-nitrosodiethylamine (ndea), Two New Potential Disinfection Byproducts; Formation during Water Disinfection with Chlorine

Nitrosamines, mainly N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA) and N-nitrosodiethylamine (NDEA) are highly mutagenic compounds that are suspected of carcinogenic activity to the human body. The aim of the paper is the evaluation of the possibility of N-nitrosomethylethylamine and N-nitrosodiethylamine formation as a result of the reaction of methylethylamine (MEA) or diethylamine (DEA) respectively with chlorine in the presence of ammonia ions. The optimal conditions of NMEA and NDEA formation were identified as a result of an experiment carried out using different molar ratios of the substrates of reaction. As the primary aim of the research was the evaluation of the possibility of NMEA and NDEA formation as a result of the reaction of methylethylamine or diethylamine respectively with chlorine in the presence of ammonia ions, a successful result obtained after GC-LRMS analysis was fundamental to the further research. Analytes from postreaction mixtures were concentrated, according to the modified procedure proposed by Mitch et al., by means of liquid/liquid extraction with the usage of methylene chloride. The N-nitrosomethylethylamine and N-nitrosodiethylamine were found in the analyzed extracts of post-reaction mixtures. Apart from NMEA and NDEA identification, the verification of other products with the usage of mass spectra library was also undertaken. The results indicated that the changes in the relative ratio of the substrates influence the concentration of NMEA and NDEA. The obtained results revealed that NMEA and NDEA are only two of the many products of the reaction taking place in the aqueous solution, which contained methylethylamine or diethylamine and ammonia ions, and was disinfected with chlorine. The other identified products are: ethyl(methyl)formamide and 3-ethyl(methyl)aminopropanenitrile. Therefore N-nitrosomethylethylamine and N-nitrosodiethylamine can be treated as new disinfection by-products similar to THMs, HAAs, MX or NDMA.