Development of a tributyl phosphate-based hydrophobic deep eutectic solvent for liquid-liquid microextraction of total parabens in beverages

Deep eutectic solvents (DESs) are new alternative solvents used in sample preparation for dissolution, extraction and preconcentration of analytes. In this work,   a tributyl phosphate (TBP)-based hydrophobic deep eutectic solvent was applied in the liquid–liquid microextraction (LLME) of total parabens in beverages.   The sample preparation procedure consisted of two main steps: the phase transfer catalyst-assisted alkaline hydrolysis of parabens and the LLME of parabens’ hydrolysate p-hydroxybenzoic acid (PHBA). The hydrolysis procedure was improved efficiently by the addition of phase transfer catalyst and the extractant became greener as the natural lauric acid (LauA) was used as the component of the DES . It was verified that the DES composed of TBP and LauA (3:1, mol/mol) was the most effective option for PHBA extraction. Response surface methodology (RSM) based on Box-Behnken design (BBD) was adopted to optimize the predominant experimental conditions. The proposed method provided satisfactory linearity (R 2  ≥ 0.9991), detection limits (0.02 μmol/L), precisions (RSDs ≤ 4.5%), recoveries (85.2% to 104.6%) and negligible matrix effects, which offered a promising way for screening total parabens in various beverage samples.