Development of dispersive liquid–liquid microextraction technique using ternary solvents mixture followed by heating for the rapid and sensitive analysis of phthalate esters and di(2-ethylhexyl) adipate

•A DLLME technique using a ternary solvent mixture was developed for the first time.•Simplex centroid experimental design was used in the selection of extraction solvents mixture.•Three solvents with different polarities including CH2Cl2, CH3Cl and CCl4 were used.•The method has high EFs (980–4500) and low LODs (0.03–0.15 μg L−1) for all analytes.

In this study, for the first time, a dispersive liquid–liquid microextraction technique using a ternary solvent mixture is reported. In order to extract five phthalate esters and di(2-ethylhexyl) adipate with different polarities from aqueous samples, a simplex centroid experimental design method was used to select an optimal mixture of ternary solvents prior to gas chromatographyflame ionization detection. In this work, dimethyl formamide as a disperser solvent containing dichloromethane, chloroform, and carbon tetrachloride as a ternary extraction solvent mixture is injected into sample solution and a cloudy solution is formed. After centrifuging, 250 μL of the obtained sedimented phase was transferred into another tube and 5 μL DMF was added to it. Then, the tube was heated in a water bath at 75 °C for 5 min in order to evaporate the main portion of the extraction solvents. Finally, 2 μL of the remained phase is injected into the separation system. Under the optimum extraction conditions, the method shows wide linear ranges and low limits of detection and quantification between 0.03-0.15 and 0.09-0.55 μg L−1, respectively. Enrichment factors and extraction recoveries are in the ranges of 980–4500 and 20–90%, respectively. The method is successfully applied in the determination of the target analytes in mineral water, soda, lemon juice, vinegar, dough, and yogurt packed in plastic packages.