In situ formation of a deep eutectic solvent for liquid-liquid microextraction of synthetic phenolic antioxidants in edible oil

A simple and ecofriendly liquid-liquid microextraction (LLME) method was developed for the extraction of synthetic phenolic antioxidants (SPAs, e.g. tert-butyl hydroquinone (TBHQ) and butylated hydroxyanisole (BHA)) in edible oil. Compared with time-consuming and cumbersome off-line prepared deep eutectic solvent (DES), the in-situ formulated DES allowed to directly add DES components into sample matrix, making the sample preparation procedure greatly simplified. Preliminary experiment indicated that the DES made of 1:2 (molar ratio) tetrabutylammonium chloride (TBAC) and acetic acid (AA) was suitable for the extraction of SPAs. Under the optimized conditions, by combining with HPLC, the in-situ DES-LLME-HPLC method showed satisfactory detection limits (0.7−1.3 μg/L), precisions (RSDs≤5.0%), enrichment factors (20.8−22.0), recoveries (89.2%–103.6%), and linearity over 5−500 μg/L (TBHQ) and 10−500 μg/L (BHA) (R2 ≥ 0.9991). In addition, the method displayed acceptable matrix effect and robustness. Hence, it is promising for the extraction and determination of SPAs in real edible oil.