Hydrophobic deep eutectic solvents as extractants for the determination of bisphenols from food-contacted plastics by high performance liquid chromatography with fluorescence detection

Abstract

As a new kind of green solvents for potential replacement of traditional volatile organic compounds, deep eutectic solvents (DESs) have been attracting more and more attention in various applications. In this work, three types of hydrophobic DESs were synthesized by simple mixing of trioctylmethyl ammonium chloride (used as hydrogen bond acceptor) with decanoic acid, ketoprofen and gemfibrozil (hydrogen bond donors), respectively, at different molar ratios. In order to evaluate the solvent characteristics of these DESs, some of the physical properties such as melting point, density, viscosity, and water contact angle were determined. Then, these hydrophobic DESs were used for the vortex-assisted liquid-liquid microextraction of bisphenol-type contaminants in water, followed by quantitative determination of bisphenols contents with high performance liquid chromatography (HPLC-FLD) coupled with fluorescence detection. For this purpose, four bisphenols, namely, 2, 2-bis(4-hydroxydiphenyl)propane (BPA), 2, 2-bis (4-hydroxyphenyl)butane (BPB), 4, 4'-(1-phenylethylidene)bisphenol (BPAP) and 4, 4'-cyclohexylidenebisphenol (BPZ) were selected as model contaminants. It was found that the enrichment factors of the proposed method were in the range from 97 to 112, depending on the structure of the analytes. Under optimal experimental conditions, the linearity ranges of the method varied from 0.3 to 700 µg L-1 with linear correlation coefficients (R2) higher than 0.996. The limit of detections (LODs) and limit of quantifications (LOQs) were in the range of 0.3-0.5 µg L-1 and 0.06-0.08 µg L-1, respectively. Furthermore, the developed method was successfully used in the extraction and determination of four bisphenols from food-contacted plastic samples.