Application of vortex-assisted liquid–liquid microextraction based on solidification of floating organic droplets for determination of some pesticides in fruit juice samples
In the present study, a green, rapid, and simple sample preparation procedure, vortex-assisted liquid–liquid microextraction based on solidification of floating organic droplets, has been developed for the analysis of ametryn, chlorpyrifos, diazinon, diniconazole, fenazaquin, oxadiazon, and penconazole with gas chromatography-flame ionization detection. In this method, menthol as a green extraction solvent was added to a sample solution and this mixture was vortexed to obtain a cloudy solution. The cloudy solution was centrifuged and fine droplets of the extraction solvent were collected on the top of the aqueous phase. The test tube was placed in an ice bath, and the floating organic droplets of menthol were solidified. Then, the aqueous phase was completely removed. Afterward, the solidified menthol remaining in the test tube was melted in a water bath. Some important parameters, such as ionic strength, vortexing time, pH, etc., were investigated and optimized. The obtained values for the limits of quantification and detection were in the ranges of 1.7–4.3 and 0.50–1.30 μg L−1, respectively. Under the optimum experimental conditions, extraction recoveries and enrichment factors were in the ranges of 53–84% and 263–421, respectively. The repeatability of the method expressed as relative standard deviation was less than 7% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 50 μg L−1 of each pesticide.