Studies on the anoxic dissipation and metabolism of pyribambenz propyl (ZJ0273) in soils using position-specific radiolabeling.
Studies on the anoxic dissipation and metabolism of pyribambenz propyl (ZJ0273) in soils using position-specific radiolabeling.
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DOI：
10.1016/j.scitotenv.2013.11.068
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发表时间：
2014-02
期刊：
影响因子：
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通讯作者：
Wei Wang-;Yichen Wang;Zheng Li;Haiyan Wang;Zhiyang Yu;Long Lu;Q. Ye
中科院分区：
文献类型：
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作者：
Wei Wang-;Yichen Wang;Zheng Li;Haiyan Wang;Zhiyang Yu;Long Lu;Q. Ye
吡苯丙酯（ZJ0273）是一种使用日益增加的多环除草剂，但研究表明，它往往在土壤中持久存在，并对轮作作物造成植物毒性。本研究采用改进的环特异性14c标记方法，将14c定位在苯甲酸环、嘧啶环或苯基环上，表征其缺氧代谢。采用液相色谱法（LC）、超低能级液相闪烁光谱法（超低能级液相闪烁光谱法）和液相质谱法（MS）对代谢产物进行分离鉴定。结果表明，厌氧降解符合一级动力学，在壤土、盐渍土和粘土中，半衰期分别约为38.7、50.2和70.7 d。共检测到5种放射性中间体（M1-M5），由于放射性标记的丢失，不同的标记得到了不同的放射色谱图，即仅对嘧啶基- 14c检测到放射性M5；M3和M4只检测到嘧啶基- 14c和苄基- 14c，而M1和M2检测到所有标签。根据它们的外观模式和LC-MS的片段，我们鉴定了M1-M5的结构，并提出它们是由脱酯、水解、酰化、单键裂解和去甲基化等反应形成的。除M4外，所有代谢物均已在好氧土壤中检测到，M4是M3的去甲基化产物，并鉴定为2-（4-羟基-6-甲氧基嘧啶-2-氧基）苯甲酸。结果表明，ZJ0273在缺氧土壤中具有较强的持久性，其降解途径和中间体与有氧代谢不同，且随土壤类型的不同而不同，表明土壤特异性和耕作方式可能是该除草剂使用的重要考虑因素。环特异性标记提供了化合物的完整分子信息，保证了结果的可靠性，可作为多环化合物代谢物谱分析的有效工具。
Pyribambenz propyl (ZJ0273) is a polycyclic herbicide with increasing use, although studies show that it tends to be persistent in soil and pose phytotoxicity to rotational crops. This study employed an improved ring-specific14C labeling method to characterize its anoxic metabolism, with14C positioned on the benzoate, pyrimidyl or benzyl rings. Separation and identification of the metabolites were achieved by liquid chromatography (LC), ultralow-level liquid scintillation spectrometry, and LC–mass spectrometry (MS). Results show that the anoxic degradation follows first-order kinetics and the half-lives are approximately 38.7, 50.2 and 70.7 d for loamy, saline and clayey soils, respectively. A total of five radioactive intermediates (M1–M5) were detected, and due to the loss of radiolabels, different radiochromatograms were obtained from different labels, i.e., radioactive M5 was only detected for pyrimidinyl-14C; M3 and M4 were only detected for pyrimidinyl-14C and benzyl-14C, while M1 and M2 were detected for all labels. Based on their appearance pattern and fragmentations from LC–MS, the structures of M1–M5 were identified, and they were proposed to form by reactions such as de-estering, hydrolysis, acylation, Csingle bondN cleavage, and demethylation. All metabolites have been previously detected in aerobic soils except M4, which is a demethylation product from M3, and identified as 2-(4-hydroxy-6-methoxypyrimidin-2-yloxy)benzoic acid. The results show that ZJ0273 is more persistent in anoxic soils, and its degradation pathways and intermediates are different from aerobic metabolism and differ with the soil types, suggesting that soil-specific and farming practices may be important considerations in the use of this herbicide. The ring-specific labeling provides full molecular information about the referred compound and guarantees the reliability of the results, and can be used as an effective tool for metabolite profiling of polycyclic compounds.