مشخصات پژوهش

Phthalate esters (PEs), along with di(2-ethylhexyl) adipate (DEHA) are chemical compounds that are widely used as plasticizers because they improve the softness and flexibility of plastics. PEs and DEHA are not chemically bound to plastics, and therefore they can be released from the plastic into the environment [1]. Due to the widespread use of the mentioned compounds, they are considered as ubiquitous environmental pollutants. In order to determine trace levels of PEs and DEHA in food samples, an extraction and preconcentration step is often required prior to their analysis by gas chromatography (GC) or liquid chromatography [2]. Several sample preparation methods have been developed for the analysis of target analytes such as liquid–liquid extraction, cloud point extraction, solid-phase extraction, liquid-phase microextraction, and dispersive liquid–liquid microextraction (DLLME) [3]. In this study, DLLME technique using a ternary solvent mixture is reported for the first time. Selecting a suitable extraction solvent is critical in all solvent extraction methods. The polarities of the analytes selected in this study and most other cases are not the same. Therefore a single extraction solvent with a known polarity cannot extract all analytes efficiently. In order to improve the extraction ability of the extraction solvent towards all interested components, three solvents with different polarities (dichloromethane, = 8.93; chloroform, = 4.81; and carbon tetrachloride, = 2.24) were chosen and solvent selectivity triangle method was used to select an optimal ternary solvent mixture. After centrifuging, the obtained sedimented phase was heated in a water bath in the presence of a few µL dimethylformamide to evaporate the main portion of the extraction solvents in order to obtain further concentration. Finally, 2 µL of the remained phase was injected into the GC–FID system. Under the optimum conditions, the method showed wide linear ranges and low limits of detection a