烯啶虫胺和唑虫酰胺在茶叶和土壤中的残留动态及风险评估

Dissipation and Risk Evaluation of Nitenpyram and Tolfenpxrad Residues in Tea and Soil

【目的】明确烯啶虫胺和唑虫酰胺两种新型杀虫剂在茶叶和土壤中的残留消解动态。【方法】应用气相色谱法建立了烯啶虫胺和唑虫酰胺推荐施用剂量和2倍推荐施用剂量在茶叶和茶园土壤中的残留量分析方法及其残留消解。【结果】2种供试药剂在茶叶和土壤中的残留量随时间的推移呈负指数函数递减,残留消解动态符合一级动力学方程,其中烯啶虫胺试验剂量在茶叶和土壤中的残留半衰期分别为6.08~6.54 d和1.52~1.68 d,在茶叶中残留量消解至MRL以下所需0.91~3.33 d;唑虫酰胺试验剂量在茶叶和土壤中的残留半衰期分别为4.47~4.74 d和1.87~1.89 d,在茶叶中残留量消解至MRL以下需5.10~8.18 d。【结论】烯啶虫胺和唑虫酰胺在茶叶和土壤中均属于易消解农药,研究结果可为烯啶虫胺和唑虫酰胺在茶园中的合理使用及其在我国规定最大允许残留限量(MRL)标准的制定提供参考。

【Objective】 Dissipation of two new insecticides and risk of the residues in tea and soil were studied.【Method】 A gas chromatographic method was applied for analyzing nitenpyram and tolfenpxrad residues in tea and soil specimens to determine the dissipation and transfer of the insecticides after application.【Result】 The insecticide residues in tea and soil decreased exponentially with time after application in a first-order kinetic function. The half-lives of nitenpyram at the recommended dosage were 6.08–6.54 d in tea and 1.52–1.68 d in soil. It took 0.91–3.33 d for the residue to degrade below the maximum allowable residue limit(MRL) in tea. For tolfenpxrad at the recommended usage level, the residue half-lives were4.47–4.74 d in tea and 1.87–1.89 d in soil. It took 5.10–8.18 d for the pesticide residue to dissipate below MRL in tea.【Conclusion】 Both nitenpyram and tolfenpxrad were found to degrade to below the MRLs in tea for safe consumption as well as in soil for environmental protection.