悬浮固化-分散液-液微萃取-气相色谱法测定蔬菜中6种拟除虫菊酯类农药

建立了QuEChERS（Quick,Easy,Cheap,Effective,Rugged and Safe的缩写）结合悬浮固化-分散液-液微萃取（DLLME-SFO）-气相色谱测定蔬菜中6种菊酯类农药残留的方法。待测样品用含1%乙酸的乙腈溶液提取,提取液经混合固相分散萃取净化后经DLLME-SFO浓缩,最后用气相色谱（ECD）进行检测。实验考察了QuEChERS方法中提取溶剂的影响,DLLME-SFO中萃取剂种类与体积,分散剂种类和体积,盐浓度等对萃取效率的影响,优化结果为以40μL十六烷为萃取剂,1000μL乙腈为分散剂,5mL水中NaCl的加入量为1.25g。结果表明,在黄瓜和番茄基质中6种菊酯类农药在5、10、50μg/kg 3个添加水平下农药的平均回收率为84.84%¹11.59%,相对标准偏差（RSD）为0.48%⁹.61%,方法的检出限（LOD,S/N≥3）和定量限（LOQ,S/N≥10）分别为0.07⁰.58μg/kg和0.22¹.94μg/kg。该方法快速、简便、灵敏、重复性好,可用于蔬菜中拟除虫菊酯类农药的快速筛查测定。 

Rapid determination of six pyrethroids in vegetables using gas chromatography combined with dispersive liquid-liquid microextraction based on solidification of floating organic droplet method

A dispersive liquid-liquid microextraction based on solidification of floating organic droplet method (DLLME-SFO) combined with QuEChERS (full name-Quick, Easy, Cheap, Effective, Rugged and Safe) was developed for the determination of six pyrethroids in vegetables with gas chromatography. The samples were extracted with acetonitrile (containing 1% (v/v) aceticacid) , after being cleaned up with mixed solid-phase dispersion, the extracts were concentrated by dispersive liquid- liquid microextraction ( DLLME) , then the concentrations were analyzed by gas chromatography. Factors affecting the extraction efficiency such as selection of extraction solvent in QuEChERS, the type and volume of extraction solvent and disperser, and salt concentration in water were investigated. In the DLLME procedure, 40μL hexadecane was used as the extraction solvent and 1000μL acetonitrile was used as the dispersive solvent and the addition of the salt in 5mL water was 1.25g. Under the optimized conditions the average recoveries in different matrices at the spiked levels of 5, 10 and 50μg/kg were 84.84%¹11.59% with the relative standard deviations of 0.48%⁹.61%. The limits of detection (LOD, S/N≥3) and quantification (LOQ, S/N≥10) of the method were 0.07⁰.58μg/kg and 0.22~ 1.94μg/kg respectively. The results demonstrated that the developed method was rapid, simple, sensitive and repeatable for analyzing pyrethroid residues in vegetables.