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

Hasan Çabuk,Yasemin Yılmaz,Elif Yıldız

doi:10.17344/acsi.2018.4877

Abstract

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%.

Highlights

Synthetic antioxidants (SAs) are a class of compounds which are capable of preventing or slowing down the oxidation reactions of substrates in food, pharmaceuticals, and other consumer products.[1]
The optimal conditions were selected based on the extraction recoveries (ERs) of the alkyl gallates
The ER was calculated based on the ratio of the amount of the analyte determined in the collected deep eutectic solvent (DES) phase to the initial amount of analyte added in the sample

Summary

Introduction

Synthetic antioxidants (SAs) are a class of compounds which are capable of preventing or slowing down the oxidation reactions of substrates in food, pharmaceuticals, and other consumer products.[1] Common SAs used as food additives in many countries include butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, propyl gallate, octyl gallate and dodecyl gallate, due to their chemical stabilities, low costs and availabilities.[2] Among SAs, alkyl gallates have been widely used as food additives to slow down or prevent lipid oxidation in lipid-rich food.[3] Contrary to their versatile and beneficial properties, the addition of excess gallates to food might cause different degrees of adverse and toxic effects on human health. The allowed amounts of SAs in food range from 100 to 200 mg kg–1 in European Union, either singly or in combination.[5]

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