QuEChERS-超高效液相色谱-串联质谱法测定吡虫啉在花椰菜和土壤中的残留

Determination of imidacloprid residues in cauliflower and soil by QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry

中文关键词:  吡虫啉  花椰菜  土壤  超高效液相色谱-串联质谱法  残留

英文关键词:imidacloprid  cauliflower  soil  ultra performance liquid chromatography-tandem mass spectrometry  residue

中文摘要:

      目的 建立测定花椰菜和土壤中吡虫啉残留的QuEChERS-超高效液相色谱-串联质谱(ultra performance liquid chromatography-tandem mass spectrometry, UPLC-MS/MS)方法, 通过田间试验研究吡虫啉在花椰菜中的残留及消解动态。方法 样品经乙腈涡旋提取15 min, 上清液加入含PSA+C18填料的小离心管中, 涡旋、离心净化后, 采用UPLC-MS/MS测定。同时测定不同采样时间的田间的花椰菜和土壤中的吡虫啉残留。结果 在0.005~0.5 mg/L范围内, 吡虫啉的进样质量浓度与其对应的峰面积间呈良好的线性关系, 相关系数r2=0.9999; 方法检出限(limit of detection, LOD)为0.001 mg/kg (S/N=3), 定量限(limit of quantification, LOQ)为0.01 mg/kg。在0.01、0.05、0.1 mg/kg的添加水平下, 吡虫啉在花椰菜中的回收率为83%~97%, 相对标准偏差为0.9%~4.5%; 吡虫啉在土壤中的回收率为80%~110%, 相对标准偏差为4.7%~10.9%。吡虫啉在花椰菜上的半衰期为2.6 d; 在土壤中的半衰期为13.6~16.9 d; 20%吡虫啉可溶性液剂分别按照有效成分30、45 g a.i./hm2剂量于花椰生长期施药, 施药2~3次, 施药间隔期为7 d, 距最后一次施药后3、7、14 d采样测定, 吡虫啉在花椰菜上残留量为<0.01~0.433 mg/kg, 均小于欧盟规定的最大残留限量0.5 mg/kg。结论 在花椰菜上使用吡虫啉, 有效剂量为30 g a.i./hm2, 施药2次时, 不会造成其在花椰菜中残留超标的风险。

英文摘要:

      Objective To establish a method for determination of imidacloprid residues in cauliflower and soil by QuEChERS coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and investigate the residue and degradation dynamics of imidacloprid in cauliflower and soil by field experiment. Methods The cauliflower and soil samples were extracted by QuEChERS with acetonitrile, cleaned up with PSA+C18 and detected by UPLC-MS/MS. The imidacloprid residues in cauliflower and soil were detected in different sampling time. Results When the concentration was in the range of 0.005 to 0.5 mg/L, the linear relationship between the mass concentration of imidacloprid and corresponding peak area was good and the linear correlation coefficient was 0.9999. The limit of detection (LOD, S/N=3) was 0.001 mg/kg, and the limit of quantitation (LOQ) in those samples was 0.01 mg/kg. The recoveries of imidacloprid in cauliflower samples were 83%-97% at the 3 spiked levels of 0.01, 0.05 and 0.1 mg/kg with the relative standard deviations (RSDs) of 0.9%-4.5%. The recoveries of imidacloprid in soil samples were 80%-110% with the relative standard deviations (RSDs) of 4.7%-10.9%. The half-life of imidacloprid in cauliflower was 2.6 d, and the half-lives of imidacloprid in soil were 13.6-16.9 d. The 20% of imidacloprid was sprayed on cauliflower at the dosages of 30 and 45 g a.i./hm2 for 2~3 times during the cauliflower growth, with 7 days between applications. The samples were collected after 3, 7, 14 d of last application, and the residues of imidacloprid in cauliflowers were <0.01-0.433 mg/kg, respectively, which were less than the maximum residue limit (MRL) of 0.5 mg/kg stipulated by EU. Conclusions When imidacloprid is used in the cauliflower field at the dose of 30 g a.i./hm2 for 2 times, it will not cause the risk of excessive residue in cauliflower.