The effect of natural organic matter polarity and molecular weight on NDMA formation from two antibiotics containing dimethylamine functional groups

摘要

N-nitrosodimethylamine (NDMA) is a disinfection byproduct preferentially formed in chloraminated water. NDMA may be formed from certain chemicals containing dimethylamine (DMA) functional groups. This reaction may be slowed by the presence of natural organic matter (NOM). In this study, N0M fractionated by size or polarity was tested for its ability to slow or impede the formation of NDMA from two DMA-containing precursors, the antibiotics tetracydine and spiramydn. The high molecular weight NOM fractions (＞ 10K Da) were shown to be the most effective in reducing the amount of NDMA formed from the precursor chemicals. The filtrate of a C-l 8 non-polar cartridge was also effective at reducing NDMA formation from tetracydine (spyramycin not tested). Therefore, polar and charged NOM components may be responsible for the reduction in NDMA formation. A possible mechanism for the reduction of NDMA formation from tetracydine is complexation due to the hydrogen bonding of the DMA functional group on tetracydine to polar phenolic functional groups in the NOM.