Analysis of herbicide mixtures in environmental samples with emulsification liquid-liquid microextraction using fatty acids deep eutectic solvents

A method was developed for the simultaneous extraction of herbicides such as 2,4 D, MCPA, ametryn, chlorothalonil, and bromacil in water and vegetable samples by emulsification liquid-liquid microextraction with fatty acids based hydrophobic deep eutectic solvents (DES). The DES were synthesised by mixing several fatty acids ratios that functioned as both the hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD). Using the DES as the microextraction solvent, several vital parameters were optimised, including the type and volume of hydrophobic DES, pH of the sample, sonication time, and type and volume of emulsifier. Then, the extracted herbicides were back-extracted into phosphoric acid solution (0.05 M). The detection limits were in the range of 0.01–2.5 ng mL⁻¹, the quantification limits were in the range of 0.03–8.3 ng mL⁻¹, and recoveries were in the range of 73.1–98.8% with RSD <10%. The greenness assessment using Analytical Eco-Scale and AGREE (Analytical GREEnness Metric Approach System) exhibited that the emulsification liquid-liquid microextraction method using DES can be considered as simple, practical, and environmentally friendly.