Hydrophobic Menthol-Based Deep Eutectic Solvent for Ultrasound-Assisted Dispersive Liquid‒Liquid Microextraction of...

Toxic amide herbicide residues pose significant risks to food safety and environmental health. In this study, an ultrasound-assisted dispersive liquid‒liquid extraction method utilizing a hydrophobic menthol-based deep eutectic solvent (DES) was developed for the efficient separation and determination of four amide herbicides in complex matrices, including vegetables, soil, and water. DES composed of decanoic acid (hydrogen bond acceptor) and menthol (hydrogen bond donor) at a molar ratio of 2:3 demonstrated superior extraction performance compared to those using lauric or oleic acid as a hydrogen bond acceptor. The extraction was equilibrated within 2 min under neutral pH conditions. Molecular docking simulations revealed that the N─H groups in the amide moieties served as the primary active sites for hydrogen bonding interactions with the DES. By integrating this green extraction technique with high-performance liquid chromatography, a robust analytical method was established, exhibiting excellent linearity (R² > 0.9991) over a wide range (1-200 ng mL^-1), with low limits of detection (0.3-0.5 ng mL^-1) and high precision (intraday RSDs ≤ 3.6%, inter-day RSDs ≤ 8.2%). The method achieved high recoveries (89.8%-116%) across various samples. Greenness assessments using the GAREEprep and Analytical Ecological Scale showed scores of 0.57 and 85, respectively, underscoring the sustainability of the method. This study presents a rapid, sensitive, and sustainable alternative for monitoring amide herbicide residues, contributing to food safety and environmental protection.