Using Ionic Liquids To Tune the Performance of Aqueous Biphasic Systems Based on Pluronic L-35 for the Purification of Naringin and Rutin

Abstract

Aqueous biphasic systems (ABS) based on Pluronic L-35, a (EO) x -(PO) y -(EO) x triblock copolymer, were determined and applied in the separation of two structurally similar flavonoids (naringin and rutin). Two sets of phase formers were paired with Pluronic L-35, one comprising conventional salts/buffer and other including cholinium-based ionic liquids (ILs). It is shown that while the conventional salts induce an unbalanced and strong salting out leading to complete extraction of flavonoids to the same phase in most of the cases (84.7 ± 0.6% ≤ R NAR ≤ 100% and 53.2 ± 0.5% ≤ R RUT ≤ 99.7 ± 0.1% with selectivities ranging from 1 to 11.8), the cholinium-based ILs provide an enhanced extractive performance. Indeed, these novel cholinium ILs/ Pluronic L-35-based ABS allowed the manipulation of the affinity of both naringin and rutin to opposite phases, thus yielding a selective separation. The best results were achieved for the system using [Ch][Bic] as phase former (R NAR = 89.6 ± 0.3 and R RUT = 32 ± 2 with a selectivity of 18.9). An integrated approach based on the sequential implementation of Na 2 SO 4 /Pluronic L-35-(step 1) and [Ch][Bic]/Pluronic L-35-based (step 2) ABS was designed to purify the flavonoids from a complex synthetic mixture simulating natural extracts. Remarkably, glucose (the main contaminant) was removed during step 1 with an extraction efficiency of 60 ± 4% to the Na 2 SO 4 -rich phase, while step 2 has enabled the efficient separation of naringin from rutin.

Extraction and purification of violacein from Yarrowia lipolytica cells using aqueous solutions of surfactants

“…The ability of the studied cholinium‐based compounds to form ABS can be ranked as follows: [Ch][DHP] > [Ch][DHC] > [Ch][Ac] > [Ch][Bic] > [Ch]Cl. The tendency observed is in agreement with previous reports for ABS composed of [Ch]X and Pluronic L‐35 …”

Separation and purification of curcumin using novel aqueous two-phase micellar systems composed of amphiphilic copolymer and cholinium ionic liquids

“…[Ch]Cl and [Ch][Ac] ions compete for water molecules around PEO chains of amphiphilic copolymers, increasing the micelle-micelle interactions and decreasing the T CP (enlargement of the two-phase region) [5,8]. Our results are in agreement with findings of Teixeira-Pinto et al [16], that observed a reduction of T CP in C 10 E 4 nonionic surfactant aqueous solutions + salts (SO…”

“…The presence of ions affected not only ATPMS equilibria but also the solutes' partition, i.e. electrolyte solutions can affect their solubility in the coexisting phases [6,8,45]. It is evident that with the addition of more hydrophobic ILs (…”

“…From the plethora of ATPS available, a growing interest on systems that use amphiphilic polymers as phase forming compounds has been observed [7,8]. The use of copolymers on developing IL-based ATPS is an interesting approach to design "more tunable" and selective systems, mainly envisaging the separation of structurally similar and/or more hydrophobic molecules.…”

“…Although the scientific community has been concerned with these aspects for the separation and purification of curcuminoids, the number of works in that field is still rather scarce. An exception is the work of Silva et al [8] that used Pluronic L35 (PEO 11 -PPO 16 -PEO 11 )-based ATPS for a selective separation of two structural similar flavonoids (naringin and rutin) by using cholinium bicarbonate as additive.…”