吡唑醚菌酯在杨梅和土壤中的残留及消解动态

为明确吡唑醚菌酯在杨梅和土壤中的残留消解规律和最终残留量，于2017年在浙江、重庆、湖南和云南4地进行了吡唑醚菌酯在杨梅及土壤中的田间残留及消解动态试验。建立了超高效液相色谱-串联质谱检测吡唑醚菌酯在杨梅和土壤中残留的分析方法。样品经乙腈水溶液提取，N-丙基乙二胺 (PSA) 和C₁₈净化，利用超高效液相色谱-串联质谱仪 (UPLC-MS/MS) 进行检测。结果表明:在0.0005~0.5 mg/L范围内，吡唑醚菌酯的质量浓度与其峰面积间呈良好的线性关系，相关系数均大于0.99。在0.01、0.5和5.0 mg/kg添加水平下，吡唑醚菌酯在杨梅中的回收率为92%~97%，相对标准偏差 (RSD) 为1.0%~2.7%；在土壤中的回收率为86%~96%，RSD为1.5%~4.1%。吡唑醚菌酯在杨梅和土壤中的定量限 (LOQ) 均为0.01 mg/kg。田间试验结果表明:吡唑醚菌酯在杨梅和土壤中的消解动态均符合一级反应动力学方程，在杨梅中的半衰期为6.6~11.8 d，在土壤中的半衰期为5.0~11.1 d。采用60%唑醚 ? 代森联水分散粒剂分别按有效成分800 mg/kg和1200 mg/kg施药3、4 次，分别于距离最后一次施药21、25和28 d采样检测发现，吡唑醚菌酯在杨梅中的最高残留量为1.4 mg/kg，均低于中国规定的其在杨梅上的最大残留限量(3.0 mg/kg)。建议采用60%唑醚 ? 代森联水分散粒剂有效成分最高使用剂量为800 mg/kg，施药间隔期7 d，最多施药3 次，采收安全间隔期为21 d。

Residue and dissipation dynamics of pyraclostrobin in waxberry (Myrica rubra) and soil

To investigate the dissipation and residues of pyraclostrobin in waxberry (Myrica rubra) and soil, the residues and dissipation dynamics of pyraclostrobin in waxberry and soil were conducted in field trials at Zhejiang, Chongqing, Hunan and Yunnan in 2017. An effective method was developed for the determination of pyraclostrobin residue in waxberry and soil. The samples were extracted with acetonitrile and water, purified with primary secondary amine (PSA) and C₁₈, and detected by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The results showed that all the correlation coefficient of calibration curves were higher than 0.99 in the range from 0.0005 to 0.5 mg/L. At the spiked levels of 0.01, 0.5 and 5.0 mg/kg, the average recoveries of pyraclostrobin in waxberry were from 92% to 97% with the relative standard deviations (RSD) ranging from 1.0% to 2.7%. The average recoveries of pyraclostrobin in soil were from 86% to 96% with the RSD ranging from 1.5% to 4.1%. The limit of quantitation (LOQ) of pyraclostrobin in waxberry and soil was 0.01 mg/kg. The field trial results showed that the dissipation equations of pyraclostrobin in waxberry and soil samples fit the first-order kinetics equation. The half-lives in waxberry were 6.6-11.8 d, and the half-lives in soil were 5.0-11.1 d. The 60% pyraclostrobin + mancozeb WG was sprayed at 800 and 1200 mg/kg on waxberry for 3-4 times and samples were collected 21, 25 and 28 d after the last application. The maximum final residue of pyraclostrobin in the waxberry was 1.4 mg/kg, which was below the maximum residual limit (3.0 mg/kg) in China. It is recommendated that the security interval of 60% pyraclostrobin + mancozeb WG for waxberry is 21 days, when it is sprayed for 3 times at the dose of 800 mg/kg with the sprayed interval 7 d.