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.