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.