吡虫啉、啶虫脒和噻虫嗪及其代谢物在茶叶种植-加工-冲泡过程中的转移规律和风险评估

Pesticide residue is one of the important factors affecting the quality and safety of tea. Imidacloprid, acetamiprid and thiamethoxam applied in tea cultivation with a large quantity are detected in dry tea frequently. Furthermore, high solubility leads to brew into the water easily with toxic metabolites. It is essential clear the transfer rule of imidacloprid, acetamiprid, thiamethoxam and their metabolites in plant-processing- infusion, which is helpful to find the key procedure to control the pesticide residue,to predict residue and risk and to reduce dietary intake risk. This study intends to identify the metabolites of the mother compounds in plant-processing- infusion process by field trial, tea processing and brewing experiment, quantitative parent compounds and metabolites in fresh leaves, dry tea and infusion, and track the target compounds. On the basis of processing factor (PF) and infusion factor (IF),it is possible to clarify the transfer law of the analytes from tea garden to tea cup, establish the residue prediction model and risk assessment prediction model.The research will provide scientific data and method to evaluate the risk of three pesticides from application in tea plant comprehensively.

农药残留是影响茶叶质量安全的重要因素之一。高水溶性农药吡虫啉、啶虫脒和噻虫嗪在茶叶种植过程中施用量大，在成茶中的检出率较高，易溶出进入茶汤，可能产生高毒代谢物，明确三种农药及其代谢物在种植-加工-冲泡过程的转移规律，找到农药残留控制的关键步骤，并预测残留量及风险变化，对于降低膳食摄入风险具有重要意义。本研究拟设计田间喷药试验、加工试验及冲泡过程，鉴定三种农药在上述步骤中的代谢物种类，定量考察母体化合物和主要代谢物在鲜叶、成茶和茶汤中的残留量，追踪目标化合物变化，获得加工因子（PF）及浸出率因子（IF），阐明目标物在茶园到茶杯过程中的转移规律，建立鲜叶残留量（C）、PF和IF基础上的农药残留预测模型和风险评估模型。为全面科学的评价三种农药在茶园施用过程带来的风险提供科学数据和方法。

本项目开展了高水溶性农药吡虫啉(IMI)、啶虫脒(ACM)和噻虫嗪(THI)及其主要代谢物在茶叶种植-加工-冲泡过程的转移规律和风险评估研究。定性鉴定了三种农药在上述过程中的代谢物，包括IMI-urea、IMI-ole、ACM-0、ACM-2-1、ACM-2-3、CLO和CGA265307，定量分析了IMI-urea、ACM-0、ACM-2-1和CLO的数量变化。建立了母体化合物和代谢物共10种目标化合物在干茶、鲜叶和茶汤中的检测方法，LOQ在0.01-0.1 mg/kg(干茶和鲜叶)和0.1-4.0 g/L（茶汤）。获得了母体化合物和主要代谢物在茶园鲜叶中的消解动态、加工系数PF和浸出率IF：吡虫啉、啶虫脒和噻虫嗪在茶园田间消解较快，在茶嫩梢中的消解半衰期T1/2在2.4-3.2天，代谢产物占母体的比例在0.2%-25%；三种农药及其代谢物在典型红茶和绿茶中的加工因子（processing factor，PF）在1.79-4.90，加工损失率在19%-68%；三种农药与代谢物的茶汤浸出率（infusion factor，IF）均较高，在0.8-1.4。提出了根据鲜叶中的残留量进行饮茶的急慢性风险评价模型。该研究为降低新烟碱农药的饮茶膳食风险和指导茶园农药使用提供了依据。