title: The formation of reactive species having hydroxyl radical-like reactivity from UV photolysis of N-nitrosodimethylamine (NDMA): kinetics and mechanism.
abstract: This study focuses on the detailed mechanism by which N-nitrosodimethylamine (NDMA) is photolyzed to form oxidized products, i.e., NO(2)(-) and NO(3)(-), and reveals a key reactive species produced during the photolysis of NDMA. Under acidic conditions, NO(2)(-) formed from the photodecomposition of NDMA was more prevalent than NO(3)(-). In this result, key species for the formation of NO(2)(-) are presumably N(2)O(3) and N(2)O(4) as termination products as well as NO and O(2) as reactants. Conversely, under alkaline conditions, NO(3)(-) was more prevalent than NO(2)(-). For this result, a key species for NO(3)(-) formation is presumably peroxynitrite (ONOO(-)). A detailed mechanistic study was performed with a competition reaction (or kinetics) between NDMA and p-nitrosodimethylaniline (PNDA) probe for hydroxyl radical (OH). It is fortuitous that the second-order rate constant for NDMA with an unknown reactive species (URS) was 5.13×10(8) M(-1) s(-1), which was similar to its published value for the reaction of NDMA+OH. Our study results showed that a key reactive species generated during NDMA photo-decomposition had hydroxyl radical-like reactivity and in particular, under alkaline conditions, it is most likely ONOO(-) as a source of nitrate ion. Therefore, for the first time, we experimentally report that an URS having OH-like reactivity can be formed during photochemical NDMA decomposition. This URS could contribute to the formations of NO(2)(-) and NO(3)(-).
authors.affiliation: Department of Bioenvironmental and Chemical Engineering, Chosun University College of Science and Technology, 290 Seosuk-dong, Dong-gu,Gwangju 501-744, Republic of Korea. kwonbg0@daum.net
authors.forename: Bum Gun
authors.initials: BG
authors.lastname: Kwon
authors.forename: Jong-Oh
authors.initials: JO
authors.lastname: Kim
authors.forename: Kyu Cheol
authors.initials: KC
authors.lastname: Namkung
mesh_terms: D004128:Dimethylnitrosamine / Q000737:chemistry* / Q000528:radiation effects*; D017665:Hydroxyl Radical / Q000737:chemistry*; D008956:Models, Chemical; D009589:Nitrogen Oxides / Q000737:chemistry; D010782:Photolysis / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D009589:Nitrogen Oxides; D017665:Hydroxyl Radical; D004128:Dimethylnitrosamine