Formation of Reactive Species Enhanced by H2O2Addition in the Photodecomposition of N-Nitrosodimethylamine (NDMA)

Abstract

This study noted that the actual mechanism of N-nitrosodimethylamine (NDMA) photodecomposition in the presence of H2O2 is missing from the previous works. This study investigated a key unknown reactive species (URS) enhanced by the addition of H2O2 during the photolysis of NDMA with H2O2, not hydroxyl radicals. In order to provide experimental evidences in support of URS formation, we have mainly used p-nitrosodimethylaniline, methanol, and benzoic acid as well-known probes of ∙OH in this study. Both loss of PNDA and formation of hydroxybenzoic acids were dependent on NDMA concentrations during the photolysis in a constant concentration of H2O2. In particular, competition kinetics showed that the relative reactivity of an URS was at least identical with ∙OH-like reactivity. In addition, the decay of NDMA was estimated to be about 65% by the direct UV light and about 35% by the reactive species or URS generated through the photolysis of NDMA and H2O2. Therefore, our data suggest that a highly oxidizing URS is formed in the photolysis of NDMA with H2O2, which could be peroxynitrite (ONOO-) as a potent oxidant by itself as well as a source of ∙OH.