Hydrolysis mechanism of methyl parathion evidenced by Q-Exactive mass spectrometry
Hydrolysis mechanism of methyl parathion evidenced by Q-Exactive mass spectrometry
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Q-Exactive 质谱证实甲基对硫磷的水解机制
DOI：
10.1007/s11356-015-5169-0
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发表时间：
2015-12-01
影响因子：
5.8
通讯作者：
Wang, Jianwei
中科院分区：
文献类型：
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作者：
Liu, Yuan;Zhang, Caixiang;Wang, Jianwei
有机磷农药（OPPs）是一种广泛使用的农药，由于其对人体中枢神经系统尤其是儿童的不良影响而受到广泛关注。尽管 OPP 的水解行为已得到很好的研究，但其水解机制仍然存在争议，特别是在各种 pH 条件下，部分原因是其相对复杂的结构和丰富的容易受到亲核试剂攻击的部分。 Q-Exactive 质谱仪是混合高分辨率质谱仪 (HRMS) 的一部分，在本研究中用于测定甲基对硫磷 (MP) 的水解产物，甲基对硫磷 (MP) 是一种 OPPs 原位缓冲水溶液，pH 范围为 1 至 13。由于 HRMS 的高灵敏度和准确性，大多数 MP 的复杂水解产物都被鉴定出来。结果表明MP的水解速率和途径具有很强的pH依赖性。随着pH的增加，MP的水解速率增加，并确定了两种不同的反应机制：SN2@P途径在高pH（例如pH ≥ 11）下主导水解过程，而SN2@C是低pH（例如pH ≤ 9）下的主要行为。这项研究有助于了解 OPP 在不同 pH 下的水解机制，并扩展 Q-Exactive 质谱在识别环境基质中有机污染物及其降解产物方面的用途。
Organophosphorus pesticides (OPPs), a kind of widely used pesticides, are currently attracting great attention due to their adverse effects on human central nervous systems, particularly in children. Although the hydrolysis behavior of OPPs has been studied well, its hydrolysis mechanism remained controversial, especially at various pH conditions, partly due to their relatively complex structures and abundant moieties that were prone to be attacked by nucleophiles. The Q-Exactive mass spectrometer, part of those hybrid high-resolution mass spectrometers (HRMS), was used to determine hydrolysis products of methyl parathion (MP), a kind of OPPs in situ buffer aqueous solution with pH ranging from 1 to 13 in this study. Most of the complex hydrolysis products of MP were identified due to the high sensitivity and accuracy of HRMS. The results demonstrated that the hydrolysis rate and pathway of MP were strong pH dependent. With the increase of pH, the hydrolysis rate of MP increased, and two different reaction mechanisms were identified: SN2@P pathway dominated the hydrolysis process at high pH (e.g., pH ≥ 11) while SN2@C was the main behavior at low pH (e.g., pH ≤ 9). This study helps understand the hydrolysis mechanism of OPPs at various pH and extends the use of Q-Exactive mass spectrometry in identifying organic pollutants and their degradation products in environmental matrices.