Solvent-vapor-assisted liquid-liquid microextraction: A novel method for the determination of phthalate esters in aqueous samples using GC-MS

A novel liquid-liquid microextraction method, namely, solvent-vapor-assisted liquid-liquid microextraction for the determination of dimethyl phthalate, diethyl phthalate, dibutyl phthalate and bis(2-ethylhexyl) phthalate in the aqueous samples using gas chromatography with mass spectrometry was developed. In the proposed method, extracting solvent was heated, and solvent vapor as the extracting phase was injected into the sample solution. As a result of the low temperature of the sample solution and higher density of the extracting phase than the aqueous medium, solvent vapor was condensed and an organic-phase drop formed in the bottom of sample tube. Because of the gas status of the extracting solvent, the surface area between the extracting solvent and the aqueous sample was remarkably high. Under the optimized conditions, tetrachloride carbon was used as an extracting solvent. The method shows high coefficient of determination (R-2) values in the range of 0.5-200 and 1.0-200 ng/mL for the target analytes. Enrichment factors and limits of detection for the studied phthalates are obtained in the ranges of 2800-3000 and 0.15-0.3 ng/mL, respectively. Recoveries and relative standard deviations were in the range of 80.0-100.0 and 2.2-7.8%, respectively. The proposed method successfully used for analysis of several aqueous samples.