A Novel Cooling/Heating Assisted Switchable Solvent Based Microextraction Process: Application for Determination of Phthalate Esters in Water Samples

A Switchable hydrophilicity Solvent (SHS) is a solvent that can reversibly switch between one forms that is miscible with water to another that forms a biphasic mixture with water. In this work, A novel temperature controlled SHS based microextraction method has been developed for the extraction and preconcentration of four phthalate esters (PAEs) from water samples prior to GC-MS analysis. For the first time, the effect of temperature in the switching of extracting solvent has been studied and the application of cooling/heating processes instead of addition of chemicals in the switchable solvent based microextraction has been used for PAEs extraction. Several parameters including solvent type, solvent volume, temperature of dissolution, temperature of separation, and salt addition are optimized. A theoretical study also has been provided to reveal the effect of cooling/heating effects on the homogenization and separation of phases. The proposed method provided some advantages such as simplicity, using low volumes of inexpensive and less hazardous reagents, rapid extraction and reduced analysis time. For the developed method, LODs and LOQs were obtained in the ranges of 0.03-0.06 and 0.1-0.2 μgL−1 respectively. Also, calibration curves were linear within the range of 0.2-100 μgL−1 for dimethyl phthalate and dibutyl phthalate, and 0.1-100 μgL−1 for diethyl phthalate and dioctyl phthalate. Enrichment factors (EFs) were found to be in the range of 110.9-116.3. The proposed method was applied for the analysis of PAEs in real water samples.