Deep Eutectic Solvent-based Vortex-assisted Dispersive Liquid–liquid Microextraction Combined with High Performance Liquid Chromatography for the Determination of Phenolic Acids in Vegetable Oils

Vortex-assisted dispersive liquid–liquid microextraction (VA-DLLME) coupled with a high performance liquid chromatography–diode array detector (HPLC-DAD) was applied for the determination of phenolic acids (gallic, ferulic, and syringic) in vegetable oils. A deep eutectic solvent (DES) – a green extraction solvent – was synthesized by stirring choline chloride and urea at 80 °C until clarification. The experimental parameters affecting extraction efficiency, such as volume of extraction solvent, ionic strength, and extraction time were all optimized. Under optimal conditions, good linearities with the phenolic acids were achieved in the range 0.1 to 10 µg g−1. The limits of detection varied between 0.010 and 0.021 µg g−1, and the limits of quantification between 0.035 and 0.071 µg g−1. The proposed DES-VA-DLLME-HPLC-DAD method is simple, time-saving, eco-friendly, and can be successfully applied to the extraction of phenolic acids from soybean, peanut, and blending vegetable oils with recoveries ranging from 75.6% to 103.4%.