Deep Eutectic Solvents in Capillary Electromigration Techniques—A Review of Recent Advancements

Deep eutectic solvents (DESs) represent a versatile and sustainable class of solvents, characterized by their low volatility, favorable biodegradability, and the ability to tailor their viscosity, polarity, and hydrogen-bonding capacity through the choice of their individual components. These characteristics have established them as powerful media in various analytical extraction and separation processes. This review presents a critical evaluation of the expanding role of DESs within the field of capillary electromigration techniques, summarizing key advancements from 2019 to mid-2025. We synthesize the current literature to delineate the benefits, persistent challenges, and future prospects of integrating DESs into capillary electrophoresis (CE)-based analytical workflows. Specifically, it systematically documents the following: (i) the diverse types of DESs employed in electrophoretic separations, (ii) proposed mechanisms underlying their influence on chiral compound resolution, and (iii) their utilization as separation media and pseudostationary phases (PSP) in capillary electromigration systems. By critically assessing their advantages and drawbacks, this review aims to provide a comprehensive perspective on the application of DESs in modern capillary electromigration techniques.