Phase Behavior of Aqueous Biphasic Systems with Choline Alkanoate Ionic Liquids and Phosphate Solutions: The Influence of pH

Abstract

Aqueous biphasic systems (ABS) composed of the choline alkanoate ionic liquids (ILs) choline acetate [Cho][OAc], choline propanoate [Cho][Pro], choline butyrate [Cho][But], and choline hexanoate [Cho][Hex], mixed with K3PO4 solutions at pH 7.2 and 14.5, were prepared and their phase diagrams were compared. The ability to form ABS with alkaline K3PO4 solutions decreased in the order [Cho][OAc] ≈ [Cho][Pro] > [Cho][But] > [Cho][Hex], while with neutral K3PO4 solutions, [Cho][OAc] could not form an ABS, and the other three ILs performed similarly. All of the biphasic regions of the ABS decreased with the increase in pH. 1H-NMR data indicated anion exchange between phases in ABS at neutral pH. The ABS at neutral pH were evaluated to extract the triazine herbicides simazine, cyanazine, and atrazine, and the ABS formed by [Cho][Pro] and the pH 7.2 K3PO4 solution has shown extraction recoveries higher than 90%.

Aqueous Biphasic Systems Comprising Natural Organic Acid-Derived Ionic Liquids

“…Even so, the presence of an extra -CH3 moiety in [CH3COO] -was expected to enlarge the biphasic zone [53], contrasting the trend observed here. Intricate tendencies in the ABS formation ability of other organic acid-derived ILs have been reported elsewhere [29,54].…”

“…With ABSs formed by cholinium-based ILs bearing natural acids as the anions and a polymer, recovery yields of 20 to 100% were obtained for immunoglobulin G by Ramalho et al [28] and Mondal et al [30]. Despite their remarkable performance [28][29][30][31], most cholinium-based ILs show little to no ability to undergo phase-separation in the presence of most salts [54,61,62], thus limiting their widespread use. In this work, by using [P4444] + or [N4444] + cations in conjugation with organic acid-derived anions, which are more easily salted-out by conventional salts, the toolbox of protein-friendly ABSs is broadened while offering a competitive performance in recovery yield and extraction efficiency.…”

Enantioseparation and determination of triazole fungicides in fruit juice by aqueous biphasic system coupled with HPLC‐MS/MS

“…Choline ILs were synthesized according to the reported methods [9,10,12,16]. Briefly, 0.1 mol organic acid or amino acid (glacial acetic acid, D-lactic acid, L-lysine, Lserine, or D-serine) was added dropwise into an aqueous solution of choline hydroxide (0.1 mol).…”

“…The ABS formed by different ILs and EOPO-2500 was developed, according to the reported methods [9,10,12,16]. An 80 wt% IL solution was added dropwise to a test tube containing the aqueous EOPO-2500 solution (80 wt%) until the solution became cloudy.…”

“…Compared with the traditional LLE or dispersive liquidliquid microextraction [7], ABS without using any organic solvent has the advantages of low pollution, easy scalability, and high biocompatibility [8][9][10][11][12], which was widely applied to the separation and purification of macromolecules [13][14][15] and organic compounds [12,16,17]. Since 2003, 1-butyl-3-methylimidazolium chloride was used to form ABS with K 3 PO 4 [18], the application of ionic liquids (IL) on the ABS formation gets much attention due to their unique properties, such as nonflammability, low volatility, and high thermal and chemical stability.…”