气相色谱-负化学离子源质谱法测定白菜中6种痕量农药残留

Determination of 6 trace pesticides in Chinese cabbage by gas chromatography-negative chemical ionization–mass spectrometry

目的建立一种气相色谱-负化学离子源质谱法(gas chromatography-negative chemical ionization-mass spectrometry,GC-NCI/MS)测定白菜中6种痕量农药残留的分析方法。方法采用乙腈超声提取,Carb/氨丙基固相萃取柱净化,酮麝香为内标物,进行气相色谱–负化学离子源质谱分析检测。结果6种农药残留在相应线性浓度范围内线性良好,回归系数r^2≥0.999,不同浓度区间加标平均回收率在89.2%~111.5%,相对标准偏差(relative standard deviation,RSD)为0.6%~12.7%。五氯硝基苯、百菌清、甲基对硫磷、α-硫丹、β-硫丹、硫丹硫酸酯6种农药残留检出下限分别为0.013、0.06、0.06、0.024、0.012、0.01 ng/mL。结论该方法回收率高,分离效果好,灵敏度高,检出下限低,快速方便,适用于实际蔬菜样品中多农药残留的痕量分析。

Objective To establish a method for the determination of 6 trace pesticides in Chinese cabbage by gas chromatography-negative chemical ionization-mass spectrometry(GC-NCI-MS). Methods Samples were ultrasonic extracted with acetonitrile,cleaned up on a carb/aminopropyl column,the internal standard used was musk ketone,then detected with gas chromatography–negative chemical ionization-mass spectrometry. Results The linearity of 6 pesticide residues is good in the corresponding linear concentration range. Within the relative range correlation coefficient r^2≥0.999,the average recovery rates of 6 pesticides varied from 89.2% to 111.5%,with the relative standard deviations of 0.6%–12.7%.The detection limits of this method for nitrobenzene,chlorothalonil,methyl parathion,α-endosulfan,β-endosulfan and endosulfan sulfate were 0.013,0.06,0.06,0.024,0.012 and 0.01 ng/mL. Conclusion The established method has high accuracy and reproducibility,and the limit of detection is relatively low,which can meet the detection requirements of residues in vegetables.