We used water-contained surfactant-based vortex- assisted microextraction (WSVAME) as a green extraction method followed by high-performance liquid chromatography (HPLC) to determine the content of quercetin as natural antioxidant in different oil samples. During the WSVAME procedure, micellar solution of cationic surfactant cetyltrimethylammonium bromide (CTAB) was injected into oil samples in a conical-bottom glass tube to form cloudy solution. The dispersion process was accelerated by vortex mixing. After extraction and phase separation by centrifugation, the lower sediment phase was directly analyzed by HPLC. Optimization of extraction factors such as the volume and concentration of extraction solvent (aqueous solution of CTAB), percentage of acetic acid added to the oil sample, and vortex time was carried out using the chemometrics approach. Under the optimum condition (30 μL of 0.15 mol L−1 CTAB solution and vortex time of 1 min) the calibration curve was linear in the range of 0.1–100.0 μg mL−1 for hazelnut, olive, and coconut oil and 0.1–120.0 μg mL−1 for almond and grapeseed oil, with correlation coefficient (R2) greater than 0.996. The limits of detection were 0.01–0.06 μg mL−1.
