漂浮固化分散液-液微萃取-气相色谱法测定液态奶中5种拟除虫菊酯类农药残留

Dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet followed by gas chromatography for the determination of five pyrethroid pesticides residues in liquid milk samples

建立了漂浮固化分散液-液微萃取（DLLME-SFO）-气相色谱配电子捕获检测器（GCECD）,同时测定液态奶中甲氰菊酯、氟氯氰菊酯、氯氟氰菊酯、氰戊菊酯和溴氰菊酯5种拟除虫菊酯类农药的分析方法。样品经预处理后,加入25μL十六烷（萃取剂）、600μL丙酮（分散剂）及质量分数为6%的氯化钠,涡旋3 min,于–5℃、10 000 r/min下离心3 min后,去除水相,融化后经气相色谱测定。结果表明：在5.0~250.0μg/kg范围内,5种拟除虫菊酯类农药的峰面积与相应的质量浓度间呈良好的线性关系,相关系数均大于0.999 0;在5~20μg/kg添加水平下,平均回收率为90%~104%,日内相对标准偏差均低于5.9%（n=6）,日间相对标准偏差均低于7.8%（n=3）;5种农药在液态奶中的检出限为0.75~2.17μg/kg,定量限为2.52~7.22μg/kg。该方法操作简便、溶剂用量少、定量准确、重现性好,适用于液态奶样品中拟除虫菊酯类农药残留分析。

A novel dispersive liquid-liquid microextraction based on solidification of floating organic droplet method（DLLME-SFO） combined with gas chromatography coupled with ECD detector was developed for the determination of five pyrethroid pesticides（fenpropathrin, cyhalothrin, cyfluthrin,fenvalerate, deltamethrin） in liquid milk. The following procedure was used for the sample pretratment：25 μL hexadecane（extraction solvent）, 600 μL acetone（dispersive solvent）, and Na Cl（6 wt%） were added, followed by vortex oscillation extraction time 3 min. Then centrifugal for 3 min at –5 ℃ and10 000 r/min, and dislodge water phase. After thawed, the sample was analysis by gas chromatography.Good linearity was obtained at concentrations from 5.00 to 250 μg/kg with correlation coefficients higher than 0.999 0 for these pyrethroids. The average recoveries of the 5 pesticides in liquid milk were in the range between 90% and 104% at spiked levels of 5 to 20 μg/kg, with intra-day relative standard deviations lower than 5.9%（n = 6） and inter-day relative standard deviations lower than 7.8%（n = 3）.The limits of detection and quantification were 0.75-2.17 μg/kg and 2.52-7.22 μg/kg, respectively. This new method is simple, solvent saving, accurate, reliable and applicable for the analysis of pyrethroid pesticides in liquid milk samples.