改良QuEChERS方法结合气相色谱测定红甜菜中20种农药残留

建立了改良的QuEChERS法结合气相色谱-电子捕获检测器用于红甜菜中20种农药残留的联合测定方法。样品中农药残留以乙腈作为提取溶剂,多壁碳纳米管分散固相萃取去除杂质,过滤后经RTX-1色谱柱分离,GC-ECD检测,外标法定量。探讨了气相色谱的程序升温条件,考察了不同提取溶剂及不同的净化方法对检测结果的影响。结果表明：在优化的色谱条件下,20种农药在0.01~0.50 mg/L（莠去津为0.03~0.50 mg/L）范围内线性关系良好,相关系数(R²)均大于0.99,并且得到很好的分离;乙腈与样品的比例为1:2,多壁碳纳米管用量为10 mg的前处理条件下,红甜菜样品在3个浓度的平均回收率为62.0%~116.5%之间,相对标准偏差为1.9%~10.9%,检出限为0.12 µg/L~0.063 mg/L,定量限为0.4 µg/L~0.21 mg/L。该方法操作简单、快速、准确,适用于红甜菜中有机氯及拟除虫菊酯类多农药残留的检测。

Determination of 20 Pesticide Residues in Red Beet by Modified QuEChERS Method Combined with Gas Chromatography

A method was developed to determine 20 pesticide residues in red beet by modified QuEChERS method combined with gas chromatography-electron capture detector. The pesticide residues in the samples were extracted by acetonitrile and cleaned up by dispersive solid-phase extraction using MWCNTs, after filtration, they were separated on RTX-1 chromatographic column, determined by gas chromatography, and quantified by the external standard method. The temperature-programmed conditions of gas chromatography were tested, and the effects of different extraction solvents and purification methods on the detection results were investigated. The results showed that under the optimized conditions, good linear relations were obtained in the range of 0.01-0.50 mg/L (Atrazine was in the range of 0.03-0.50 mg/L), the correlation coefficients (R²) were all higher than 0.99, and 20 pesticides were well separated. The pre-treatment condition was as follow: acetonitrile: sample was 2:1, and the amount of MWCNTs was 10 mg. The average recoveries of red beet were 62.0%-116.5% at three spiked concentration levels with relative standard deviations (RSDs) of 1.9%-10.9%, the limits of detection were 0.12 μg/L - 0.063 mg/L, and the limits of quantitation were 0.4 μg/L - 0.21 mg/L. This method is simple, rapid, accurate, and could be used for the determination of organochlorine and pyrethroid residues in red beet.