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利用分散固相萃取(QuEChERS)改良技术建立了玉米中多菌灵、吡虫啉、乙草胺、异丙甲草胺残留的液相色谱-串联质谱分析方法。样品经1%甲酸乙腈提取,采用N-丙基乙二胺(PSA)和十八烷基键合硅胶(C_(18))共萃取净化,C_(18)色谱柱分离,0.1%甲酸-乙腈为流动相梯度洗脱,质谱采用电喷雾正离子(ESI~+)模式电离,多离子检测模式(MRM)定性,基质标准曲线外标法进行定量分析。结果表明:玉米基质中多菌灵、吡虫啉、乙草胺、异丙甲草胺在0.5μg/kg~100μg/kg浓度范围内,具有很好的线性关系,其相关系数(R)均大于0.995。在3个加标浓度下,4种农药的平均回收率在88.0%~112.0%之间,相对标准偏差(RSD,n=5)不大于9.5%。该方法对多菌灵、吡虫啉、乙草胺和异丙甲草胺的检出限分别为0.025、0.15、0.15μg/kg和0.025μg/kg,满足玉米中4种农药残留分析的要求。
Liquid chromatography - tandem mass spectrometry was established for the determination of carbendazim, imidacloprid, acetochlor and metolachlor in corn using the modified QuEChERS technique. The samples were extracted with 1% formic acid in acetonitrile and purified by co-extraction with N-propyl ethylenediamine (PSA) and octadecyl-bonded silica gel (C 18) (ESI ~ +) mode ionization, multi-ion detection mode (MRM) qualitative, matrix standard curve external standard method for quantitative analysis. The results showed that there was a good linear relationship between carbendazim, imidacloprid, acetochlor and metolachlor in the range of 0.5μg / kg ~ 100μg / kg, and the correlation coefficients (R) were all above 0.995 . The average recoveries of the four pesticides ranged from 88.0% to 112.0% at 3 spiked levels, with a relative standard deviation (RSD, n = 5) of not more than 9.5%. The detection limits of carbendazim, imidacloprid, acetochlor and metolachlor in this method were 0.025,0.15,0.15μg / kg and 0.025μg / kg, respectively, which met the requirements of four pesticide residue analysis in maize.