AWWA ACE58345

N-nitrosodimethylamine (NDMA) formation by the reaction of dimethylamine (DMA) with nitrite was studied in the absence and in the presence of HOCl at pH 7. The presence of HOCl significantly enhanced NDMA formation by nitrite. In the absence of HOCl, the concentration of NDMA formed by DMA with nitrite was increased from 0.34 ug/L to 0.65 ug/L as the nitrite concentration increased from 0.05 mM to 1.0 mM. However, in the presence of HOCl, the formation of NDMA was significantly enhanced from 0.14 ug/L to 15.47 ug/L as the nitrite concentration increased from 0.01 mM to 1.0 mM. Additional studies in mixtures of 15N and 14N labeled nitrite and ammonia indicated that the source of nitrogen in the nitroso group of NDMA may come from both ammonia and nitrite but their contribution to NDMA formation is governed by two different mechanisms. Includes 5 references, table, figures.