QuEChERS-HPLC-MS/MS法分析丙硫菌唑及其代谢物在小麦和土壤中的残留

Degradation Dynamics and Residue Analysis of Prothioconazole and Its Metabolite Prothioconazole-Desthio in Wheat and Soil by QuEChERS-High Performance Liquid Chromatography-Tandem Mass Spectrometry

采用QuEChERS前处理方法结合高效液相色谱-串联质谱测定40%丙硫·戊唑醇悬浮剂中丙硫菌唑及其代谢物硫酮菌唑在小麦和土壤中的残留量。经方法验证,丙硫菌唑及其代谢物硫酮菌唑在仪器中检出限为2×10-3 ng,方法定量限为0.02 mg/kg。丙硫菌唑在小麦籽粒、小麦植株和土壤中的添加回收率分别为87.3%～103.0%、9 3. 6%～1 0 0. 3%和8 5. 0%～1 0 0. 5%;硫酮菌唑在小麦籽粒、小麦植株和土壤中的添加回收率分别为93.2%～109.9%、92.7%～101.9%和81.7%～95.6%。研究残留降解动态,结果表明丙硫菌唑及其代谢物硫酮菌唑在小麦植株中降解动态符合一级动力学指数模型,丙硫菌唑在江苏、河南和北京三地小麦植株中的半衰期分别为4.4、1.8 d和3.3 d,硫酮菌唑在江苏、河南和北京三地小麦植株中的半衰期分别为6.2、2.9 d和6.0 d。丙硫菌唑在小麦籽粒、小麦植株和土壤中的最终残留量分别为<0.02、<0.02～0.225 mg/kg和<0.02～0.033 mg/kg;硫酮菌唑在小麦籽粒、小麦植株和土壤中的最终残留量分别为<0.02、<0.02～0.282 mg/kg和<0.02～0.049 mg/kg。4 0%丙硫·戊唑醇悬浮剂以3 0 0ga. i./h m2剂量,施药2次时,丙硫菌唑在小麦籽粒中的最终残留浓度符合GB 2763—2016要求,可以安全使用。

The degradation dynamics and residues of prothioconazole and its metabolite prothioconazole-desthio from 40%prothioconazole+tebuconazole suspension concentrate(SC)in wheat and soil were investigated by QuEChERS-high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).The limit of detection(LOD)for both prothioconazole and prothioconazole-desthio was 2×10-3 ng,and the limit of quantitation(LOQ)was 0.02 mg/kg.The recoveries of prothioconazole from spiked wheat grains and straw and soil were 87.3%–103.0%,93.6%–100.3%and 85.0%– 100.5%,respectively,and the recoveries of prothioconazole-desthio were 93.2%–109.9%,92.7%–101.9%and 81.7%–95.6%,respectively.The degradation of prothioconazole and its metabolite in wheat straws was fitted to a first-order reaction kinetic model.The half-lives of degradation of prothioconazole in wheat straw from Jiangsu,Henan and Beijing were 4.4,1.8 and 3.3 d,respectively.The half-lives of degradation of prothioconazole-desthio in wheat straw from Jiangsu,Henan and Beijing were 6.2,2.9 and 6.0 d,respectively.The final residues of prothioconazole in wheat grains and straw and soil were<0.02,<0.02–0.225 and<0.02–0.033 mg/kg,respectively.The final residues of prothioconazole-desthio were<0.02,<0.02–0.282 and<0.02–0.049 mg/kg,respectively.The spray application of 40%prothioconazole+tebuconazole SC twice at a dose of 300 g a.i./hm2 gave a final residual prothioconazole concentration in wheat grains consistent with the national standard(GB 2763-2016);thus,it can be safely used.