Vortex-assisted deep eutectic solvent reversed-phase liquid–liquid microextraction of triazine herbicides in edible vegetable oils

In this study, four triazine herbicides—namely, simazine, ametryn, prometryn and terbuthylazine—were separated and determined using high-performance liquid chromatography coupled with ultraviolet detector (HPLC-UVD). The deep eutectic solvent (DES) formed by tetrabutylammonium chloride ([N4444]Cl, TBA) and ethylene glycol (EG) was selected as the extraction solvent of vortex-assisted reversed-phase liquid-liquid microextraction (VA-RPLLME). The application of the hydrophilic DES expands the range of choice for LLME. The experimental parameters affecting the extraction recoveries, including the amount of the DES, the sample volume and the vortex time, were investigated and optimized by the design of experiments (DoE) methodology. A quadratic model, namely central composite face-centered (CCF) design featuring 20 runs was used instead of the conventional trial and error approach. Under optimum conditions, the limits of determination (LODs) of the method were 0.60–1.50 μg L−1. The enrichment factors for the analytes ranged from 27 to 31. The extraction recoveries were in the range of 84.1–104.9%, and the intra-day, inter-day and intermediate relative standard deviations (RSDs) were less than 8.4%. Finally, the method was applied for the determination of triazine herbicides in vegetable oil samples. The obtained recoveries were in the range of 60.1–107.2% and RSDs were lower than 8.1%. In general, VA-RPLLME can be complementary to the present available methods for the determination of triazine herbicides in vegetable oil samples.