气相色谱法同时检测青菜中毒死蜱和氯氰菊酯残留量的方法研究

Study on Simultaneous Determination of Residues of Chlorpyrifos and Cypermethrin in Brassica chinensis L. by GC-μECD

为更准确、简便地检测青菜中毒死蜱与氯氰菊酯残留,采用气相色谱-微池电子捕获检测器法（GC-μECD）,建立了同时测定青菜中这2种农药残留量的分析方法.样品采用乙腈超声提取,过弗罗里硅土固相萃取柱净化,用丙酮/正己烷（1∶9,V/V）淋洗,淋洗液水浴蒸发近干后以正己烷定容,应用HP-5毛细管柱程序升温分离,微池电子捕获检测器测定,外标法定量.毒死蜱和氯氰菊酯的线性范围分别为0.005～5 mg/L和0.01～5 mg/L,相关系数（r）均大于0.99,添加浓度在0.1～1 mg/kg时,平均回收率为84.2％～116.9％,相对标准偏差（RSD）为2.4％～12.7％,检出限分别为0.0002 mg/kg和0.003 mg/kg.该方法简便、快速、灵敏,准确度及精密度均满足农药多残留检测的要求,适用于青菜中毒死蜱和氯氰菊酯残留量的检测分析.

In order to simultaneously determine residues of chlorpyrifos and cypermethrin in Brassiea ehinensis L. more accurately and more conveniently, a gas chromatographic method with micro-electron capture detector （GC-IxECD） was developed. The pesticide residues were extracted from Brassiea ehinensis L. with aeetonitrile under ultrasonie wave and the extraet was eleaned-up by self-made florisil solid-phase extraction column and eluted with aeetone/n-hexane（l：9, V10. The eluent from column was evaporated to near dryness in water-bath with constant temperature and diluted with n-hexane to volume. The analytes were separated by a heated HP-5 eapillary eolumn, determined by GC with IxECD and quantified by external standard of the peak area. The liner range of ehlorpyrifos and cypermethrin were 0.005-5 mg/L and 0.01- 5 mg/L, with correlation coefficients （r） higher than 0.99. Mean recoveries of two analytes in Brassiea ehinensis L. ranged from 84.2% to 116.9% at spiked levels of 0.1-1 mg/kg, and the relative standard deviations （n=-3） from 2.4% to 12.7%. Limits of detection for ehlorpyrifos and eypermethrin were 0.0002 mg/kg and 0.003 mg/kg, respectively. The method was simple, rapid, sensitive and can meet the requirements of pesticide residue analysis on accuracy and preeision, thus practical for the simultaneous analysis of chlorpyrifos and cypermethrin residues in Brassiea ehinensis L..