Supramolecular deep eutectic solvents applied in analytical studies: A review

Deep eutectic solvents (DESs) have gained widespread application as green solvents in analytical chemistry due to their low volatility, nonflammability, ease of synthesis, and biodegradability. Recently, a new subclass of DESs, known as supramolecular deep eutectic solvents (SUPRADESs), has emerged. SUPRADESs are non-covalent eutectic mixtures formed by self-assembled hydrogen-bonding interactions between components, including macrocyclic compounds such as cyclodextrins. They have attracted increasing attention in analytical studies owing to the intrinsic properties of DESs in combination with the host–guest inclusion capabilities of macrocyclic compounds. This review provides an overview of SUPRADESs from their development history and classification based on their type (binary SUPRADES and ternary SUPRADES). It also reviews recent advancements in their applications to analytical studies, such as sample pretreatment and separation methods, by categorizing them based on their specific roles (extraction solvent, desorption agent, sorbent material or sorbent modifier, and chiral selector). Compared to conventional solvents and DESs, SUPRADESs have demonstrated improved extraction and desorption efficiencies, enhanced enantioseparation performance, or better analyte stability. Finally, the limitations (e.g., high viscosity and lack of rational selection strategy) and future perspectives of the SUPRADES are briefly discussed to provide a valuable outlook for further applications of SUPRADESs in analytical studies.