In this study, we reveal the capacity of imidacloprid (a neonicotinoid insecticide) to photoinduce the nitration and nitrosation of three aromatic probes (phenol, resorcinol, and tryptophan) in water. Using a gas-flow reactor and a NOx analyzer, the production of gaseous NO/NO2 was demonstrated during irradiation (300-450 nm) of imidacloprid (10-4 M). Quantum calculations showed that the formation of NOx proceeds via homolytic cleavage of the RN-NO2 bond in the triplet state. In addition to gaseous NO/NO2, nitrite and nitrate were also detected in water, with the following mass balance: 40 ± 8% for NO2, 2 ± 0.5% for NO, 52 ± 5% for NO3-, and 16 ± 2% for NO2-. The formation of nitro/nitroso probe derivatives was evidenced by high-resolution mass spectrometry, and their yields were found to range between 0.08 and 5.1%. The contribution of NO3-/NO2- to the nitration and nitrosation processes was found to be minor under our experimental conditions. In contrast, the addition of natural organic matter (NOM) significantly enhanced the yields of nitro/nitroso derivatives, likely via the production of triplet excited states (3NOM*) and HO•. These findings reveal the importance of investigating the photochemical reactivity of water contaminants in a mixture to better understand the cocktail effects on their fate and toxicity.

中文翻译：

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辐照含有吡虫啉的微污染物混合物后产生有毒硝基和亚硝基产物的新途径：NOx的作用和天然有机物的作用。

在这项研究中，我们揭示了吡虫啉（一种新烟碱类杀虫剂）能够光诱导水中三种芳香族探针（苯酚，间苯二酚和色氨酸）的硝化和亚硝化作用。使用气流反应器和NOx分析仪，在吡虫啉（10-4 M）辐照（300-450 nm）期间证明了气态NO / NO2的产生。量子计算表明，NOx的形成通过三重态的RN-NO2键的均相裂解而进行。除气态NO / NO2外，水中还检测到亚硝酸盐和硝酸盐，其质量平衡为：NO2为40±8％，NO为2±0.5％，NO3-为52±5％和16±2％用于NO2-。高分辨率质谱法证明了硝基/亚硝基探针衍生物的形成，发现其收率范围为0.08％至5.1％。在我们的实验条件下，发现NO3- / NO2-对硝化和亚硝化过程的贡献很小。相反，添加天然有机物（NOM）可能通过产生三重激发态（3NOM *）和HO•显着提高了硝基/亚硝基衍生物的收率。这些发现揭示了研究混合物中水污染物的光化学反应性的重要性，以更好地了解混合物对其命运和毒性的影响。