吡唑醚菌酯在柑橘汁加工过程中的残留动态

为明确柑橘汁加工过程中吡唑醚菌酯的残留动态，于2019年在湖南省洪江市和重庆市江津区两地以普通甜橙为研究对象，采用40%吡唑 ? 咪鲜胺水乳剂按5倍最高推荐剂量(有效成分166.7 mg/kg) 施药3次，按照橙汁典型商业化加工工艺过程进行加工，采用QuEChERS前处理方法结合高效液相色谱-串联质谱(HPLC-MS/MS)检测吡唑醚菌酯的残留量。方法确证结果表明:在0.0025~0. 5 mg/L(皮精油基质为0.005~1 mg/L)范围内，吡唑醚菌酯的基质匹配标准曲线线性关系良好(相关系数大于0.9905)。在0.01、0.1和2 mg/kg (皮精油基质为0.2、2和20 mg/kg) 3个添加水平下，吡唑醚菌酯在柑橘加工产品及清洗液中的平均回收率为63%~110%，相对标准偏差(RSD)为1.3%~9.6%。柑橘汁加工试验结果表明:榨汁过程加工因子(PF)的最佳评估值为<0.02]是降低吡唑醚菌酯残留的高效途径，吡唑醚菌酯易在皮渣(PF为1.2)及皮精油(PF为15.6)中富集。研究结果可为吡唑醚菌酯的膳食风险评估提供参考。

Residual dynamics of pyraclostrobin in citrus juice processing

To assess the residual dynamic of pyraclostrobin during citrus juice processing, the field trials were conducted in Jiangjin District, Chongqing City and Hongjiang City, Hunan Province in 2019 with application of 40% pyraclostrobin + prochloraz water emulsion at five-fold maximum recommended dosage (166.7 mg a.i./kg) for three times on sweet orange, and citrus samples after application were processed according to the typical commercial processing procedure of orange juice, and the processed samples were finally determined by QuEChERS method combined with HPLC-MS/MS. The method validation results showed that, within the linear range of 0.0025-0.5 mg/L (except it was 0.005-1 mg/L for the matrix of peel essential oil), the matrix matched calibration curves of pyraclostrobin fit the linear relationship in both citrus processing products and cleaning liquid with correlation coefficient greater than 0.990 5. The average recoveries of pyraclostrobin in citrus processing products and cleaning liquid ranged from 63 % to 110 % and the relative standard deviation was 1.3%-9.6% at the three spiking levels of 0.01, 0.1 and 2 mg/kg (0.2, 2 and 20 mg/kg for peel essential oil). The results of citrus juice processing showed that the residues of pyraclostrobin in juice decreased significantly during the juicing process with the best estimated processing factor (PF) of <0.02, while pyraclostrobin was enriched in citrus peel essential oil and pomace with the best estimated PF of 15.6 and 1.2, respectively. This study provided reference for the dietary risk assessment of pyraclostrobin in orange juicing process.