Supramolecular solvents based on quaternary ammonium salts and perfluorinated compounds for dispersive liquid-liquid microextraction of phthalates

In this study, eight hydrophobic supramolecular (SUPRA) solvents composed of tetrabutylammonium chloride and tetradecyltrimethylammonium bromide as amphiphiles and four perfluorinated compounds (hexafluoroisopropanol, trifluoroacetic acid, pentafluoropropionic acid and heptafluorobutyric acid) as coacervation-inducing agents were developed. The SUPRA phase volumes were determined as a function of individual concentrations of the system components. The extraction properties of the SUPRA solvents for the extraction of phthalates from the model aqueous solutions were investigated and their applicability as sample diluents for the reversed-phase HPLC separations of phthalates was tested. Finally, the solvent consisting of tetradecyltrimethylammonium bromide and hexafluoroisopropanol was applied for dispersive liquid-liquid microextraction of phthalates from wastewater samples prior to HPLC analysis. Under optimised extraction conditions, the enrichment factors were around 75. The calibration curves were linear (R2 ≥ 0.9965) for the concentration level between 1.00 and 50.0 μg/L and the detection limits were in the range 0.3–0.6 μg/L. The recoveries of the phthalates of the developed method for the spiked wastewater samples were 93.1–104.4%, with the relative standard deviation values less than 7.4%.