Water-contained surfactant-based vortex-assisted microextraction method combined with liquid chromatography for determination of synthetic antioxidants from edible oil

• An organic solvent free extraction method was developed.
• Synthetic antioxidants in edible oil sample were extracted into aqueous phase.
• Vortex shaking could enhance the extraction efficiency.
• Method optimization was done based on the chemometrics approach.
• The proposed method is simple, sensitive and environmental friendly.

For the first time, a novel water-contained surfactant-based vortex-assisted microextraction method (WSVAME) was developed for the extraction of two synthetic antioxidants (t-butyl hydroquinone (TBHQ) and butylated hydroxyanisole (BHA)) from edible oil samples. The novel microextraction method is based on the injection of an aqueous solution of non-ionic surfactant, Brij-35, into the oil sample in a conical bottom glass tube to form a cloudy solution. Vortex mixing was applied to accelerate the dispersion process. After extraction and phase separation by centrifugation, the lower sediment phase was directly analyzed by HPLC. The effects of the four experimental parameters including volume and concentration of extraction solvent (aqueous solution of Brij-35), percentage of acetic acid added to the oil sample and vortex time on the extraction efficiency were studied with a full factorial design. The central composite design and multiple linear regression method were applied for the construction of the best polynomial model based on experimental recoveries. The proposed method showed good linearity within the range of 0.200–200 μg mL−1, the square of correlation coefficient higher than 0.999 and appropriate limit of detection (0.026 and 0.020 μg mL−1 for TBHQ and BHA, respectively), while the precision for inner-day was ≤3.0 (n = 5) and it was ≤3.80 (n = 5) for inter-day assay. Under the optimal condition (30 μL of 0.10 mol L−1 Brij-35 solution as extraction solvent and vortex time 1 min), the method was successfully applied for determination of TBHQ and BHA in different commercial edible oil samples. The recoveries in all cases were above 95%, with relative standard deviations below 5%. This approach is considered as a simple, sensitive and environmentally friendly method because of biodegradability of the extraction phase and no use of organic solvent in the extraction procedure.