Extraction of parabens from personal care products using a pH-responsive hydrophobic deep eutectic solvent: experimental design and COSMO-RS evaluations

Abstract

A simple and efficient liquid–liquid microextraction method assisted by a pH-responsive hydrophobic deep eutectic solvent (LLME-HDES) was developed for the extraction of three parabens from personal care product samples. The phase separation of the DES composed of l-menthol and ethylene glycol was achieved by changing the acidity of the sample solution. Using the central composite design, the influence of experimental variables including the concentration of potassium hydroxide, volume of HDES, and volume of hydrochloric acid were investigated, and the results revealed that the extraction of parabens was performed using 6 M of KOH, 75 μL of DES, and 105 μL of HCL. The limits of detection (LODs) for the target compounds were 0.2–0.5 μg L⁻¹. The intra-day repeatability of the developed extraction method at 100 μg L⁻¹ ranged from 3.5% to 6.2%. The thermodynamic model of target parabens and individual components in the structure of HDES was investigated using COSMO-RS.