Vortex-Assisted Deep Eutectic Solvent-Based Liquid-Liquid Microextraction for the Analysis of Alkyl Gallates in Vegetable Oils.

This study investigates the feasibility of using hydrophilic deep eutectic solvent (DES) as green and effective extractant for the extraction and preconcentration of alkyl gallates from vegetable oils. In a typical experiment, 120 αL of choline chloride:ethylene glycol DES was added to 1.0 g of oil sample which was previously diluted with 1 mL of n-hexane. The extraction was accelerated by vortex stirring of the two phases. At this stage, hydrogen bonding interactions between the phenyl hydroxyls of alkyl gallates and chloride anion of choline salt were likely the main forces driving the extraction. After extraction, the analytes in the DES phase were separated and determined by high-performance liquid chromatography with ultraviolet detection. The method detection limits for propyl gallate and octyl gallate were 2.1 and 4.6 αg kg-1, respectively. The precision of the method varied between 4.6-6.4% (intra-day) and 5.4-7.5% (inter-day). The recoveries (accuracies) obtained from spiked vegetable oil samples were in the range of 78-106%.