Pan Rong, Chen Hong-Ping, Zhang Ming-Lu, Wang Qing-Hua, Jiang Ying, Liu Xin
Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, China; Graduate School of Chinese Academy of Agricultural Sciences, Beijing, China.
Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, China; Key Laboratory of Tea Quality and safety & Risk Assessment, Ministry of Agriculture, Hangzhou, China.
PLoS One. 2015 Sep 25;10(9):e0138309. doi: 10.1371/journal.pone.0138309. eCollection 2015.
Residue levels of dimethoate and its oxon metabolite (omethoate) during tea planting, manufacturing, and brewing were investigated using a modified QuEChERS sample preparation and gas chromatography. Dissipation of dimethoate and its metabolite in tea plantation followed the first-order kinetic with a half-life of 1.08-1.27 d. Tea manufacturing has positive effects on dimethoate dissipation. Processing factors of dimethoate are in the range of 2.11-2.41 and 1.41-1.70 during green tea and black tea manufacturing, respectively. Omethoate underwent generation as well as dissipation during tea manufacturing. Sum of dimethoate and omethoate led to a large portion of 80.5-84.9% transferring into tea infusion. Results of safety evaluation indicated that omethoate could bring higher human health risk than dimethoate due to its higher hazard quotient by drinking tea. These results would provide information for the establishment of maximum residue limit and instruction for the application of dimethoate formulation on tea crop.
采用改进的QuEChERS样品前处理方法和气相色谱法，对茶叶种植、加工和冲泡过程中乐果及其氧代代谢物（氧乐果）的残留水平进行了研究。乐果及其代谢物在茶园中的消解符合一级动力学，半衰期为1.08 - 1.27天。茶叶加工对乐果的消解有积极影响。绿茶和红茶加工过程中乐果的加工因子分别在2.11 - 2.41和1.41 - 1.70范围内。氧乐果在茶叶加工过程中既有生成也有消解。乐果和氧乐果的总量导致80.5 - 84.9%的大部分转移到茶汤中。安全性评价结果表明，由于饮茶时氧乐果的危害商较高，其对人体健康的风险高于乐果。这些结果将为制定乐果在茶叶上的最大残留限量提供信息，并为乐果制剂在茶树种植上的应用提供指导。
