QuEChERS-超高效液相色谱串联质谱法测定噻虫嗪在芥菜叶和芥菜根中的残留和消解动态研究

目的 建立QuEChERS-超高效液相色谱串联质谱(ultra performance liquid chromatography-tandem mass spectrometry, UPLC-MS/MS)测定芥菜叶和芥菜根中噻虫嗪残留的分析方法, 并研究田间试验条件下噻虫嗪在芥菜叶和芥菜根中的残留及消解动态。方法 样品经乙腈涡旋提取, QuEChERS(Quick, Easy, Cheap, Effective, Rugged, Safty)方法净化后, 采用UPLC-MS/MS测定, 外标法定量分析。结果 噻虫嗪在0.002~1.0 mg/L范围内线性关系良好, 相关系数r=0.9999, 方法检出限(limit of detection, LOD, S/N=3)为0.001 mg/kg, 定量限(limit of quantitation, LOQ)为0.005 mg/kg。在0.005、0.1、1.0 mg/kg的添加水平下, 噻虫嗪在芥菜叶中的回收率为81%~111%, 相对标准偏差为2%~10%; 噻虫嗪在芥菜根中的回收率为70%~104%, 相对标准偏差为2%~10%。测得噻虫嗪在芥菜叶和芥菜根上残留量分别为<0.005~1.56 mg/kg和0.005~0.16 mg/kg, 小于中国规定的最大残留限量(maximum residue limit, MRL)5 mg/kg(芥菜叶)和0.3 mg/kg(芥菜根)。在芥菜上使用噻虫嗪, 有效剂量为30 g a.i./hm2, 施药2次时, 不会造成其在芥菜叶和芥菜根中残留超标的风险。结论 该方法简单、准确、实用性强, 适用于芥菜叶和芥菜根中噻虫嗪的定量分析。

Determination of thiamethoxam in mustard leaf and mustard root by QuEChERS-ultra performance liquid chromatography tandem mass spectrometry and research its degradation dynamics

Objective To establish a method for determination of hiamethoxam residues in mustard by QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry (UPLC/MS/MS), and conducte the residues and decline dynamics of thiamethoxam in mustard field by field experiments. Methods The mustard leaf and mustard root samples were extracted with acetonitrile and purified by QuEChERS (quick, easy, cheap, effective, rugged, safety), detected by UPLC/MS/MS, and quantified by external standard method. Results When the concentration was in the range of 0.002 to 1.0 mg/L, the linear relationship of thiamethoxam was good, the linear correlation coefficient was 0.9999, the limit of detection (LOD, S/N=3) was 0.001 mg/kg, the limits of quantitation (LOQs) in those samples were 0.005 mg/kg. The recoveries of thiamethoxam in mustard leaf and mustard root samples at three spiked levels of 0.005, 0.1 and 1.0 mg/kg were ranged from 81% to 111%, 70% to 104%, and the relative standard deviation were 2%?10%. The residues of thiamethoxam in mustard leaf and mustard root were <0.005?1.56 mg/kg and 0.005?0.16 mg/kg, respectively, which was less than the maximum residue limit (MRL) of 5 mg/kg (mustard leaf) and 0.3 mg/kg (mustard root) stipulated in China. When thiamethoxam was used in the mustard field at the dose of 30 g a.i./ hm2 for 2 times, it would not cause the risk of excessive residue in mustard leaf and mustard root. Conclusions This method is simple, accurate and practical, which is suitable for quantitative analysis of thiamethoxam in mustard leaf and mustard root.