Determination of pyrethroid pesticides residues in vegetable oils using liquid–liquid extraction and dispersive liquid–liquid microextraction followed by gas chromatography–flame ionization detection

A simple, fast and economical method has been developed for the determination of fenpropathrin, sumithrin, cyhalothrin, permethrin and deltamethrin in vegetable oils. The method is based on a dispersive liquid–liquid microextraction (DLLME) technique after a preliminary liquid–liquid extraction step, which is followed by a gas chromatography–flame ionization detection or gas chromatography–mass spectrometry determination. Initially oil samples were partitioned in a dimethylformamide (DMF)–hexane mixture and then DMF was removed and used as a disperser solvent in the following DLLME procedure in which μL-level of 1,1,2-trichloroethane was used as an extraction solvent. The detection limits ranged from 0.02 to 0.16 mg kg−1 and the relative standard deviations (RSD %) for four repeated experiments (C = 0.2 and 0.6 μg kg−1 of each pesticide) varied from 2% to 13%, and enrichment factors were in the ranges of 40–70. In p value of 0.9, neither significant matrix effects nor interferences were observed by employing the proposed treatment in analysis of oil samples, and the extraction recoveries obtained for the samples spiked with 0.2, 0.6 and 1.1 mg kg−1 levels varied from 109 ± 3% to 85 ± 5%. The method was successfully applied in determination of target analytes in vegetable oils.