Deep Eutectic Solvents as effective media for the extraction of small molecules from natural sources

Objectives Deep Eutectic Solvents (DESs) represent an emerging class of biorenewable solvents usually prepared by mixing two or three safe and inexpensive components able to form an eutectic mixture with a melting point further below that of the individual components. Due to their low toxicity and biodegradability they are progressively replacing conventional volatile organic compounds (VOCs) in several fields of science. An increasing number of studies, in particular, have reported the feasibility of extracting bioactive compounds from natural sources (Ruesgas-Ramón et al., JAFC, 2017, 65, 3591). Our efforts of late have focused on the use of these media in the extraction of contaminants, such as mycotoxins, from food matrices. Methods An analytical method for the determination of the mycotoxin Ochratoxin A (OTA) in wheat and some processing products has been developed and validated using choline chloride (ChCl)-based solvent as privileged and biodegradable extraction media (Piemontese et al. Molecules, 2017, 22, 121). We have then implemented the method to include a larger screening on many solid food matrices using several DESs with different physical-chemical characteristics. Results Using the ChCl/urea (1:2)/water (+ 40% w/w) mixture, the analytical performances, in term of recovery and repeatability for durum wheat, bread crumbs, and biscuits, proved to be comparable to those obtained with conventional and hazardous VOCs, which are typically employed according to the standard and official methods. The tunability of DESs is promising to extend the use of the validated method to other food commodities. Preliminary results obtained with the ChCl/lactic acid (1:2)/water (+25% w/w) mixture have revealed good extraction performances on a wide number of solid matrices.