QuEChERS-超高效液相色谱-串联质谱法测定山葵中乐果的残留量

Determination of dimethoate residues in horseradish by quechers-ultra performance liquid chromatography-tandem mass spectrometry

目的建立QuEChERS-超高效液相色谱-串联质谱法测定山葵中乐果残留量的分析方法。方法山葵样品用乙腈和水提取,盐析后取上清液,上清液经C_(18)、PSA、无水MgSO_4净化,在电喷雾正离子(electronic spray ion,ESI^+)模式下,通过优化色谱分离条件,用超高效液相色谱-串联质谱法采用多反应监测(multiple reaction monitoring,MRM)模式检测,结合乐果标准曲线进行外标法定量。结果方法中乐果在0.00125~0.5 mg/L浓度范围内线性关系良好,线性方程为Y=2371831.1X+10169.6,相关系数r=0.9998(n=6)。山葵中乐果在0.01、0.1、2 mg/kg 3个添加浓度水平下,平均回收率88.1%~97.8%,相对标准偏差为1.0%~3.5%(n=5)。该方法乐果在山葵中定量限为0.01 mg/kg。结论所建立的分析方法操作简便,分离、净化效果良好,灵敏度、准确度和精密度符合农药残留检测要求,可用于山葵中乐果残留量检测。

Objective To establish a method for the determination of dimethoate residues in horseradish by quechers-ultra performance liquid chromatography-tandem mass spectrometry. Methods Horseradish samples were extracted with acetonitrile and water, the supematant was taken and purified by C18, PSA and anhydrous MgSO4 after salting-out, in the electrospray positive ion （ESI^＋） mode, by optimizing chromatographic separation conditions, and the multi-reaction monitoring （MRM） mode was used for ultra performance liquid chromatography-tandem mass spectrometry, combined with the dimethoate standard curve to quantify. Results The method has a good linear relationship in the concentration range of 0.00125-0.5 mg/L. The linear equation was Y=2371831.1X＋10169.6, and the correlation coefficient （r） was 0.9998 （n=6）. The average recoveries of dimethoate were 88.l%-97.8% at the concentrations of 0.01, 0.1 and 2 mg/kg, and the relative standard deviations （RSDs） were 1.0%-3.5% （n=5）. The limit of quantitative of the method was 0.01 mg/kg in horseradish. Conclusion The method is simple to operate, effective in separation and purification, and the sensitivity, accuracy and precision can meet the requirements of pesticide residue detection, which can be used for detection of residues in horseradish.