Electrophoresis in Deep Eutectic Solvents

In the past few years there has been an increase in the use of deep eutectic solvents (DES) for a range of chemical processes, including synthetic applications, electrochemistry, and sample extraction. There has been some incorporation of DES into separation processes, but that has been limited in comparison to the adoption of the solvents in other disciplines. On the rare occasions when they have been incorporated into capillary electrophoretic (CE) separations the DES is typically a minor component to the total background electrolyte (BGE) – potentially entering the realm where the unique structures of these solvents breakdown in favor of water’s hydrogen boding. The challenge to working with a pure DES in CE is obviously when you look at the most common of these solvents, they contain a 33-50% mole ratio of choline chloride – they are incredibly conductive, not to mention very viscous. However, not all DES are prepared with salts like choline chloride, there is an entire class of DES that are non-ionic. There are also other molecules that are weakly ionic and may also form DES. What happens when those solvents are incorporated into the BGE? We have identified that replacing choline chloride with dimethylethanolamine, in the same mole ratio, still results in a unique solvent when combined with ethylene glycol. This solvent has very low conductivity, and can be used as the BGE in CE without incurring an excessive current. This presentation will detail the results of our modification of this BGE, both with water, and with trace amounts of ionic compounds. Our goal is to elucidate how we can modify and control the electroosmotic flow and separation characteristics in these novel solvents.