Microextraction of bioactive compounds using deep eutectic solvents: a review

Analytical scientists are actually developing sustainable methods for the analysis of environmental samples. In particular, replacing classical, toxic solvents by safer solvents is a principle of green chemistry. For instance, deep eutectic solvents, formed by mixing two or more components by hydrogen bonding, appear promising. Here, we review the use of deep eutectic solvents for liquid–liquid, liquid–solid and combined extractions. We compare the use of deep eutectic solvents with conventional organic solvents for extraction. Overall, deep eutectic solvents showed better extraction efficiency and higher recovery compared to water and conventional organic solvents. In particular, deep eutectic solvents showed about 93–99% efficiency for protein extraction. The extraction efficiency often depends on the physicochemical properties of deep eutectic solvents.