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Carbon, Hydrogen, and Nitrogen Isotope Fractionation Trends in N-Nitrosodimethylamine Reflect the Formation Pathway during Chloramination of Tertiary Amines
Environmental Science & Technology ( IF 11.4 ) Pub Date : 2017-11-06 00:00:00 , DOI: 10.1021/acs.est.7b03919
Stephanie Spahr 1, 2 , Urs von Gunten 1, 2, 3 , Thomas B. Hofstetter 1, 3
Affiliation  

Assessing the precursors and reactions leading to the carcinogenic N-nitrosodimethylamine (NDMA) during drinking water disinfection is a major challenge. Here, we investigate whether changes of 13C/12C, 2H/1H, and 15N/14N ratios of NDMA give rise to isotope fractionation trends that can be used to infer NDMA formation pathways. We carried out compound-specific isotope analysis (CSIA) of NDMA during chloramination of four tertiary amines that produce NDMA at high yields, namely ranitidine, 5-(dimethylaminomethyl)furfuryl alcohol, N,N-dimethylthiophene-2-methylamine, and N,N-dimethylbenzylamine. Carbon and hydrogen isotope ratios of NDMA function as fingerprints of the N(CH3)2 moiety and exhibit only minor isotope fractionation during the disinfection process. Nitrogen isotope ratios showed that NH2Cl is the source of the N atom of the nitroso group. The large enrichment of 15N in NDMA was indicative of the isotope effects pertinent to bond-cleavage and bond-formation reactions during chloramination of the tertiary amines. Correlation of δ15N versus δ13C values of NDMA resulted in trend lines that were not affected by the type of tertiary amine and treatment conditions, suggesting that the observed C and N isotope fractionation in NDMA may be diagnostic for NDMA precursors and formation pathways during chloramination.

中文翻译:

N-亚硝基二甲胺的碳,氢和氮同位素分馏趋势反映了叔胺氯化过程中的形成途径

在饮用水消毒过程中评估导致致癌性N-亚硝基二甲基胺(NDMA)的前体和反应是一项重大挑战。在这里,我们调查NDMA的13 C / 12 C,2 H / 1 H和15 N / 14 N比值的变化是否引起同位素分馏趋势,可用于推断NDMA形成途径。我们在氯化四种高产NDMA的叔胺的氯化过程中进行了NDMA的化合物特异性同位素分析(CSIA),这是雷尼替丁,5-(二甲基氨基甲基)糠醇,N,N-二甲基噻吩-2-甲基胺和N, ñ-二甲基苄胺。NDMA的碳和氢同位素比率充当N(CH 32部分的指纹,并且在消毒过程中仅表现出较小的同位素分馏。氮同位素比表明,NH 2 Cl是亚硝基基团N原子的来源。NDMA中15 N的大量富集表明在叔胺氯化过程中与键断裂和键形成反应有关的同位素效应。的δ相关15 N对δ 13NDMA的C值导致趋势线不受叔胺类型和处理条件的影响,这表明在NDMA中观察到的C和N同位素分馏可以诊断氯化过程中的NDMA前体和形成途径。
更新日期:2017-11-07
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