Magnetic deep eutectic solvents in microextraction techniques

Magnetic deep eutectic solvents (MDESs) have recently produced a torrent of pioneering applications in endless areas of sample preparation. By including a magnetic nanomaterial (e.g., magnetic nanoparticles) or a paramagnetic anion (e.g., [FeCl4]-) in their structure, MDESs exhibit a strong response under the application of an external magnetic field. Furthermore, the use of MDESs, as a sorbent or solvent in extraction techniques, have been scarcely employed to develop green analytical methods, characterized by the avoid of time-consuming steps and the use of toxic organic solvents, as well as the application of small amounts of MDESs, for the determination of organic and inorganic contaminants, drugs, proteins, among others in environmental, food and biological matrices. This review highlights the application of MDESs in sample preparation in analytical chemistry. Challenges and future outlooks of new MDESs are also presented.