Application of Ternary Deep Eutectic Solvent in Liquid-Phase Microextraction Techniques

In recent years, deep eutectic solvents (DESs) have experienced widespread growth due to their potential use as "green solvents" replacing traditional organic solvents. DESs present important advantages such as easy preparation, high affinity, low toxicity and accessibility of their components. Therefore, they have been applied as extracting agents in liquid phase microextraction techniques. Despite the DESs advantages, some limitations have been described related to their solubility, viscosity, selectivity and stability, consequently, an alternative described is binary DESs incorporation of a third component (ternary deep eutectic solvents) have been developed as an alternative. This new type of solvents improves some physical and chemical characteristics as well as extraction efficiency and selectivity, besides to exhibit good stability in polar or nonpolar matrices, high ratio dispersion and separation from extraction media, good selectivity and affinity toward various compounds. This review classifies ternary DESs based on the components used in their synthesis, as hydrophilic ternary DESs, hydrophobic ternary DESs, magnetic ternary DESs, supramolecular ternary DESs, and polymeric ternary DESs and their sub-classifications. Emerging trends in the development of ternary DES, including the interaction mechanisms for the extraction process, their application in various matrices, and the results obtained for different target compounds, are described and discussed.