Deep eutectic solvents (DESs) are a mixture of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) molecules that can consist, respectively, of natural plant metabolites such as sugars, carboxylic acids, amino acids, and ionic molecules, which are for the vast majority ammonium salts. Media such as DESs are modular tools of sustainability that can be pointed toward the extraction of bioactive molecules due to their excellent physicochemical properties, their relatively low price, and accessibility. The present review focuses on the application of DESs for protein extraction and purification. The in-depth effects and principles that apply to DES-mediated extraction using various renewable biomasses will be discussed as well. One of the most important observations being made is that DESs have a clear ability to maintain the biological and/or functional activity of the extracted proteins, as well as increase their stability compared to traditional solvents. They demonstrate true potential for a reproducible but more importantly, scalable protein extraction and purification compared to traditional methods while enabling waste valorization in some particular cases.

The development of a green, safe, and accurate sample preparation method for the determination of trace metal elements in environmental samples is of great importance. Choline chloride-based deep eutectic solvents (DESs) were used to extract heavy metal elements from litterfall and the target analytes were measured using inductively coupled plasma optical emission spectrometry. Factors such as the type, ratio, dosage, and extraction time and temperature of the DESs were studied. A DES system based on choline chloride and maleic acid had the highest extraction efficiency of 98.5%, 88.4%, 90.2%, and 93.7% for Cd, Cu, Zn, and Fe. Under the optimized conditions, the limits of detection and limits of quantification were in the range of 0.04–0.70 and 0.13–2.30 mg kg⁻¹. The repeatability (n = 3), estimated in terms of the relative standard deviation, ranged from 1.14% to 3.40%. The proposed method was validated for accuracy using GBW10087. Notably, the energy consumption of the newly developed method was only one-fifth that of a traditional acid digestion method. This work not only presents an environmentally friendly method for the determination of trace element concentrations in environmental samples but also deepens our understanding of DES systems.