Determination of neonicotinoid insecticide residues in edible oils by water-induced homogeneous liquid-liquid extraction and dispersive liquid-liquid extraction followed by high performance liquid chromatography-diode array detection

In this paper, a new version of homogenous liquid-liquid extraction based on water-induced mode combined with dispersive liquid-liquid microextraction has been developed for the extraction and preconcentration of four neonicotinoid insecticides from edible oils. In this method, initially an appropriate organic solvent (acetone) is added to edible oil to form a homogeneous solution and then a few microliters of de-ionized water are added as a phase separation agent. By this action, a two-phase system is formed: a lower phase, a mixture of the organic solvent and de-ionized water containing the target insecticides and an upper phase, the edible oil. After extraction of the insecticides from oil, a portion of the lower phase is removed and used in the following dispersive liquid-liquid microextraction step. High performance liquid chromatography-diode array detection was used in the separation and determination of the analytes. Under the optimum extraction conditions, the method showed low limits of detection (0.11-0.36 ng mL(-1)) and quantification (0.40-1.03 ng mL(-1)), good extraction recoveries (58-83%) and high enrichment factors (294-418). Finally the proposed method was applied to analyze the target analytes in different edible oil samples.