Development of dispersive liquid–liquid microextraction combined with gas chromatography–mass spectrometry as a simple, rapid and highly sensitive method for the determination of phthalate esters in water samples

A simple, rapid and efficient method, the dispersive liquid–liquid microextraction (DLLME) in conjunction with gas chromatography–mass spectrometry (GC–MS), has been developed for the extraction and determination of phthalate esters (dimethyl phthalate, diallyl phthalate, di-n-butyl phthalate, benzyl butyl phthalate, dicyclohexyl phthalate and di-2-ethylhexyl phthalate) in water samples. Factors relevant to the microextraction efficiency, such as the kind of extraction, the disperser solvent and their volume, the salt effect and the extraction time were investigated and optimized. Under the optimized extraction conditions (extraction solvent: chlorobenzene, volume, 9.5 μL; disperser solvent: acetone, volume, 0.50 mL, without salt addition and extraction time below 5 s), the figures of merit of the proposed method were evaluated. The values of the detection limit of the method were in the range of 0.002–0.008 μg L−1, while the RSD% value for the analysis of 1 μg L−1 of the analytes was below 6.8% (n = 4). A good linearity (0.9962 ≥ r2 ≥ 0.9901) and a broad linear range (0.02–100 μg L−1) were obtained. The method exhibited enrichment factors and recoveries, ranging from 681 to 889 and 68.1 to 88.9%, respectively, at room temperature (25 ± 1 °C). Finally, the proposed method was successfully utilized for the preconcentration and determination of the phthalate esters in different real water samples and satisfactory results were obtained.