HPLC-MS/MS法对琯溪蜜柚中吡唑醚菌酯残留的测定及套袋对残留量的影响

Determination of pyraclostrobin residue in Citrus maxima by HPLC-MS/MS and bagging effect on the residues

【目的】明确吡唑醚菌酯在琯溪蜜柚上使用的安全性以及套袋对残留量的影响,对其残留消解动态进行研究。【方法】通过田间试验,在蜜柚上进行施药,设置2种施药剂量,分套袋和无套袋2种处理,利用高效液相色谱-串联质谱法进行残留检测。【结果】吡唑醚菌酯在1~500μg·L-1浓度范围内线性关系良好(r 2=0.9993),检出限为0.7μg·kg-1。在2、50、1000μg·kg-1添加水平下,吡唑醚菌酯的平均回收率为83.8%~105.8%,相对标准偏差(RSD)为2.9%~9.1%,该方法能够满足检测要求。吡唑醚菌酯在蜜柚中的残留消解动态符合一级动力学方程,套袋处理的半衰期(T 1/2)为5.10~5.26 d,无套袋处理的T 1/2为4.48~4.79 d。【结论】吡唑醚菌酯套袋处理的半衰期略长于无套袋处理的半衰期,但施药后65 d在蜜柚中均没有检出吡唑醚菌酯残留。

【Aim】In order to identify the safety of pyraclostrobin in Citrus maxima and the effect of bagging on pesticide residues,a study on the residual degradation dynamics of pyraclostrobin was conducted.【Method】Pyraclostrobin was sprayed on C.maxima at two dosages with bagging and no-bagging in a field experiment,and then residues were determined by HPLC-MS/MS.【Result】Results showed a good linear relationship(r 2=0.9993)in the concentration range of 1-500μg·L-1 for pyraclostrobin,the detection limit of pyraclostrobin was 0.7μg·kg-1.When the spiked levels were 2,50 and 1000μg·kg-1,the average recovery rates of pyraclostrobin varied between 83.8%and 105.8%,with relative standard deviation(RSD)ranging from 2.9%to 9.1%.Therefore,the method met the detection requirement.The residual degradation dynamics of pyraclostrobin followed the first-order kinetic equation.The half-life(T 1/2)of pyraclostrobin was 5.10-5.26 d in the bagging treatment,and 4.48-4.79 d in the no-bagging.【Conclusion】The half-life(T 1/2)of pyraclostrobin was slightly longer in the bagging treatment,the residues of pyraclostrobin in C.maxima were all not detected after 65 days.