分散固相萃取气相色谱-负化学离子源质谱法测定大豆和玉米中20种农药的残留量

建立了一种大豆和玉米中20种农药残留量的分散固相萃取气相色谱-负化学离子源质谱分析方法。样品经乙腈提取并浓缩后加入N-丙基乙二胺（PSA）、石墨化碳黑和C18 3种填料进行分散固相萃取净化,气相色谱-负化学离子源质谱分时段选择离子监测技术测定与确证,外标法定量。所有农药在20～400 μg/L范围内线性均良好;方法的定量限(LOQ)均不高于2 μg/kg;在5,10和20 μg/kg 3个添加水平下所有农药的平均回收率均处于70%～130%之间,相对标准偏差(RSD)低于17%;运用该方法检测大豆和玉米样品时没有干扰现象。

Determination of 20 kinds of pesticide residues in soybeans and corn using gas chromatography-negative chemical ionization mass spectrometry coupled with offline disperse solid-phase extraction

A method was developed for the determination of 20 kinds of pesticide residues in soybeans and corn with the technique of offline disperse solid-phase extraction and gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The pesticides interested were extracted twice from the samples with acetonitrile. The combined extract was concentrated to dryness and redissolved in acetonitrile, then cleaned up by dispersive solid-phase extraction with sorbents of N-propyl ethylene diamine （PSA）, graphited carbon black, and C18, and determined and confirmed by GC-NCI/MS. The recoveries of all pesticides were in the range of 70%-130% at three spiked levels （5, 10 and 20 μg/kg）, and the relative standard deviations were below than 17%. The linearity of the method was good in the concentration range of 20-400 μg/L, and limits of quantification (LOQs) were no more than 2 μg/kg. The method is selective well with no interference and suitable for the confirmatory of pesticide residues in soybeans and corn.