Collaborative Innovation Center of Henan Grain Crops, National Key Laboratory of Wheat and Maize Crop Science, College of Plant Protection , Henan Agricultural University , Wenhua Road No. 95 , Zhengzhou 450002 , China.
Key Laboratory of Agri-food Safety of Anhui Province, College of Resources and Environment , Anhui Agricultural University , Hefei 230036 , China.
J Agric Food Chem. 2020 Feb 26;68(8):2329-2339. doi: 10.1021/acs.jafc.9b06857. Epub 2020 Feb 18.
The heavy application of neonicotinoid insecticides in agricultural production has burdened the environment. In the present study, interactions of two neonicotinoid insecticides imidacloprid and thiamethoxam with dissolved organic matter (DOM) were investigated by spectroscopic techniques, molecular modeling, and density functional theory (DFT) calculations. The static mechanism of imidacloprid and thiamethoxam quenching the endogenous fluorescence of DOM was assessed through time-resolved analyses. During the binding process, a protein-like substance binds imidacloprid and thiamethoxam later than a humic-like substance, as analyzed by two-dimensional correlation spectroscopy, but more strongly than the humic-like substance, as suggested by molecular modeling and DFT calculations. The conformational changes of DOM are attributed to imidacloprid and thiamethoxam, as assessed with three-dimensional spectra. Fourier transform infrared spectroscopy indicated that DOM binds imidacloprid and thiamethoxam by hydroxyl, aliphatic C-H, amide I, and carboxyl to form stable DOM-imidacloprid and DOM-thiamethoxam complexes. Understanding the changes in the structural conformation of humic-like and protein-like substances with imidacloprid and thiamethoxam helps further understand the fate of the neonicotinoids in the environment.
农业生产中大量使用新烟碱类杀虫剂给环境带来了负担。本研究采用光谱技术、分子模拟和密度泛函理论（DFT）计算研究了两种新烟碱类杀虫剂吡虫啉和噻虫嗪与溶解有机质（DOM）的相互作用。通过时间分辨分析评估了吡虫啉和噻虫嗪猝灭 DOM 内源性荧光的静态机制。在结合过程中，二维相关光谱分析表明，与腐殖质样物质相比，一种类蛋白物质与吡虫啉和噻虫嗪的结合速度较慢，但结合强度较大，分子模拟和 DFT 计算也表明了这一点。通过三维光谱评估 DOM 的构象变化归因于吡虫啉和噻虫嗪。傅里叶变换红外光谱表明，DOM 通过羟基、脂肪族 C-H、酰胺 I 和羧基与吡虫啉和噻虫嗪结合，形成稳定的 DOM-吡虫啉和 DOM-噻虫嗪配合物。了解与吡虫啉和噻虫嗪相互作用时腐殖质样和类蛋白物质结构构象的变化有助于进一步了解新烟碱类杀虫剂在环境中的命运。
