高效液相色谱-串联质谱法测定多杀菌素在甘蓝和土壤中的残留及消解动态

建立了高效、快速、灵敏的测定甘蓝及土壤中多杀菌素残留量的高效液相色谱-串联质谱(HPLC-MS/MS)检测方法,并研究了多杀菌素在甘蓝和土壤中的残留及消解动态。样品用乙腈提取,经 N -丙基乙二胺(PSA)分散固相萃取(DSPE)净化后用HPLC-MS/MS检测分析。该方法对甘蓝和土壤中多杀菌素的检出限(LOD)为6×10-12 g,定量限(LOQ)为0.005 mg/kg;在0.005~0.5 mg/kg添加水平下,多杀菌素在甘蓝中的平均回收率为87% ~95%,相对标准偏差(RSD)为6% ~10%,在土壤中的平均回收率为86% ~100%, RSD 为4% ~8%。2011年北京、安徽和湖南 3地的消解动态研究结果表明,多杀菌素在甘蓝和土壤中的消解符合一级反应动力学方程,半衰期分别为0.83~1.16 d和0.88~1.17 d。2011年和2012年的最终残留试验结果表明,在推荐剂量和1.5倍推荐剂量(有效成分26.25 和39.38 g/hm2)下,在甘蓝长至成果的1/2大小时施药2~3次,距末次药后1 d时甘蓝中多杀菌素的残留量远低于我国制定的最大残留限量(MRL)标准2.0 mg/kg。

Residue and decline of spinosad in cabbage and soil by high-performance liquid chromatography-tandem mass spectrometry

An efficient,rapid and sensitive analytical method was developed for the determination of spinosad in cabbage and field soil by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).Its decline and residue behavior in cabbage and soil were also evaluated.Samples were primarily extracted by acetonitrile,cleaned up with PSA dispersive solid phase extraction (DSPE) and finally analyzed by HPLC-MS/MS.The limit of detection and limit of quantification were 6×10^-12 g and 0.005 mg/kg respectively in both cabbage and soil.Average percentage of recovery,RSDs were 87%-95%,6%-10% in cabbage and 86%-100%,4%-8% in soil respectively.Experiments in Beijing,Anhui and Hunan were conducted in 2011.The results showed decline of spinosad both in cabbage and soil,which were well fitted with the first-order kinetics,and the half-lives were 0.83-1.16 d and 0.88-1.17 d,respectively.The final residue experiment were conducted in 2010 and 2011.The results showed that at the recommend dosage and 1.5 times the dosage 26.25 and 39.38 g(a.i.)/hm²],residues in cabbage after 1 day in both treatments were all below MRL value(2.0 mg/kg,by China).