滇红茶加工过程中氟虫腈及其代谢物降解规律分析及膳食暴露评估

为了探究滇红茶加工过程中氟虫腈及其代谢物的残留降解变化规律以及膳食暴露风险,本研究首先利用超高效液相色谱-串联质谱,TPT净化小柱,建立了滇红茶中氟虫腈及其代谢物的高灵敏度快速测定方法,在负离子MRM监测模式下,氟虫腈及其代谢物在0.5~100 μg/mL浓度范围内线性关系良好,最低检出限为0.4 μg/kg,不同添加浓度下的平均回收率范围为84.4%~95.5%,达到痕量检测的要求;通过在滇红茶鲜叶上喷洒氟虫腈及其代谢物,采摘后模拟滇红茶加工过程,对滇红茶加工的主要步骤取样并测定氟虫腈及其代谢物含量,结果表明,氟虫腈及其代谢物含量在滇红茶加工过程中不断降低,揉捻和干燥两个步骤可引起氟虫腈及其代谢物大量降解,降解率范围分别为37.5%~41.2%和65.1%~70.1%;HQ计算结果表明,氟虫腈及其代谢物的膳食暴露风险较低,而总危害指数HI大于1,膳食暴露风险不可接受。目前氟虫腈及其代谢物已在茶叶中禁止使用,4种农药同时使用的可能性较小,但应引起重视。

Degradation of Fipronil and Its Metabolites during Processing of Yunnan Black Tea and Dietary Exposure Assessment

The purpose of this study was to investigate the residual degradation of fipronil and its metabolites during the processing of black tea and its dietary exposure risk. In this study,ultra-high performance liquid chromatography-tandem mass spectrometry and TPT SPE columns were used to establish a high-sensitivity and rapid determination method for fipronil and its metabolites in black tea. In the negative ion MRM monitoring mode,the linear range of fipronil and its metabolites was 0.5~100 μg/mL,the linear relationship was good,and the minimum detection limit was 0.4 μg/kg. The average recovery rate under different additive concentrations was 84.4%~95.5%,which met the requirements of trace detection. By spraying fipronil and its metabolites in the fresh leaves of the black tea,and simulating the processing of the indigo tea,and sampling and measuring the content of fipronil and its metabolites in the main steps of the processing of the indigo tea,the results showed that the content of fipronil and its metabolites was continuously reduced during the processing of Yunnan black tea,and fipronil and its metabolites were largely degraded in the two steps of rolling and drying,and the degradation rates of these two steps ranged from 37.5% to 41.2% and 65.1% to 70.1%,respectively. The results of HQ calculation showed that the dietary exposure risk of fipronil and its metabolites was low,while the total hazard index HI was greater than 1,and the dietary risk was unacceptable. At present,fipronil and its metabolites have been banned in tea. It is less likely to use four pesticides in sapling tea,but should be taken seriously.