Stimuli-responsive (switchable) deep eutectic solvents in microextraction: Status, challenges and prospects in food safety and environmental analysis.
Abstract
Deep eutectic solvents (DESs) have attracted considerable attention as green extraction solvents; however, their application in microextraction is often limited by difficult phase separation, poor recyclability, and the need for additional separation steps. Stimuli-responsive or switchable deep eutectic solvents (S-DES) overcome these limitations through reversible hydrophilic-hydrophobic transitions triggered by external stimuli such as CO2/N2, pH, or temperature, enabling efficient extraction, rapid phase separation, and solvent reuse. This review critically examines the current status, challenges, and prospects of S-DES in microextraction for food safety and environmental analysis. The design principles, classification, and switching mechanisms of CO2/N2-, pH-, temperature-, magnetic-, photo-, and electro-responsive S-DES are discussed and critically assessed, together with the molecular interactions governing analyte extraction. Recent applications in liquid-phase microextraction for pesticides, antibiotics, pharmaceuticals, mycotoxins, heavy metals, and emerging contaminants are systematically evaluated. The role of computational tools, including COSMO-RS, density functional theory, molecular dynamics simulations, and machine learning, in understanding extraction mechanisms and guiding solvent design is also highlighted. Current challenges include limited validation in complex matrices, a lack of standardized switching protocols, and the underutilization of temperature-responsive systems. Future research directions focusing on temperature-responsive extraction platforms, multi-class contaminant extraction, and AI-assisted solvent design are discussed. S-DES show strong potential for developing greener, simpler, and more efficient microextraction methods for food safety and environmental monitoring.
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