Ionic Liquid Aqueous Two-phase System Research Articles

Efficient separation of mannan–protein mixtures by ionic liquid aqueous two-phase system, comparison with lectin affinity purification

Analysis of carbohydrates from complex biological samples often requires their isolation from proteins and other contaminants to avoid interference. An effective separation of mannan–protein mixtures by 1-butyl-3-methylimidazolium bromide/K2HPO4 ionic liquid aqueous two-phase system (IL-APTS) is reported. Extraction efficiency of bovine serum albumin (BSA) ranged from 92% to 97% while extraction efficiency of mannan reached values from 95% to about 100% depending on phase and/or model sample composition. On the contrary, lower efficiency of BSA removal (73–84%) was recorded for lectin affinity purification with concanavalin A–triazine bead cellulose (Con A-TBC); the low mannan-binding capacity was limiting factor here. The size exclusion chromatography pattern of model mannan–BSA samples after both IL-APTS and Con A-TBC treatments were consistent with the spectrophotometric component analysis. In case of biological experiment, the ionic liquid separation technique was superior in pre-purification of 2-aminobenzamide-labelled mannan from cell culture medium prior to HPLC-FLD analysis.

Magnetic ionic liquid aqueous two-phase system coupled with high performance liquid chromatography: A rapid approach for determination of chloramphenicol in water environment

A novel organic magnetic ionic liquid based on guanidinium cation was synthesized and characterized. A new method of magnetic ionic liquid aqueous two-phase system (MILATPs) coupled with high-performance liquid chromatography (HPLC) was established to preconcentrate and determine trace amount of chloramphenicol (CAP) in water environment for the first time. In the absence of volatile organic solvents, MILATPs not only has the excellent properties of rapid extraction, but also exhibits a response to an external magnetic field which can be applied to assist phase separation. The phase behavior of MILATPs was investigated and phase equilibrium data were correlated by Merchuk equation. Various influencing factors on CAP recovery were systematically investigated and optimized. Under the optimal conditions, the preconcentration factor was 147.2 with the precision values (RSD%) of 2.42% and 4.45% for intra-day (n=6) and inter-day (n=6), respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.14ngmL−1 and 0.42ngmL−1, respectively. Fine linear range of 12.25ngmL−1–2200ngmL−1 was obtained. Finally, the validated method was successfully applied for the analysis of CAP in some environmental waters with the recoveries for the spiked samples in the acceptable range of 94.6%–99.72%. Hopefully, MILATPs is showing great potential to promote new development in the field of extraction, separation and pretreatment of various biochemical samples.

Tube Radial Distribution Flow Separation in a Microchannel Using an Ionic Liquid Aqueous Two-Phase System Based on Phase Separation Multi-Phase Flow.

Ionic liquid aqueous two-phase systems were delivered into a capillary tube to achieve tube radial distribution flow (TRDF) or annular flow in a microspace. The phase diagram, viscosity of the phases, and TRDF image of the 1-butyl-3-methylimidazolium chloride and NaOH system were examined. The TRDF was formed with inner ionic liquid-rich and outer ionic liquid-poor phases in the capillary tube. The phase configuration was explained using the viscous dissipation principle. We also examined the distribution of rhodamine B in a three-branched microchannel on a microchip with ionic liquid aqueous two-phase systems for the first time.

Phase diagram of ionic liquid aqueous two-phase systems with N-butylpyridinium tetrafluoroborate, ammonium Citrate/Sodium acetate, and water from 308.15 K to 328.15 K

In this study, the phase diagrams and liquid–liquid equilibrium data for two-phase systems of N-butylpyridinium tetrafluoroborate ([BPy]BF4)+ammonium citrate ((NH4)3C6H5O7) have been experimentally determined at 308.15K, 313.15K, 318.15K and 328.15K. Sodium acetate (CH3COONa)+water had also been determined at 308.15K, 318.15K and 328.15K. The binodal data were fit to the Merchuk equation and to two empirical equations with several parameters. Good agreement was obtained among these models.

Green determination of aconitum alkaloids in Aconitum carmichaeli (Fuzi) by an ionic liquid aqueous two-phase system and recovery of the ionic liquid coupled with in situ liquid–liquid microextraction

A green and effective extraction system based on the use of an ultrasound-assisted IL-ATPS was developed for the determination of aconitum alkaloids.

Synthesis, magnetism, aqueous-two phase formation and physical properties of novel guanidinium-based magnetic ionic liquids

A novel magnetic ionic liquid aqueous two-phase systems (MILATPs) has been developed, based on a series of novelly synthesized guanidinium-based magnetic ionic liquids.

A resolution approach of racemic phenylalanine with aqueous two-phase systems of chiral tropine ionic liquids

Aqueous two-phase systems (ATPS) based on tropine type chiral ionic liquids and inorganic salt solution were designed and prepared for the enantiomeric separation of racemic phenylalanine. The phase behavior of IL-based ATPS was comprehensive investigated, and phase equilibrium data were correlated by Merchuk equation. Various factors were also systematically investigated for their influence on separation efficiency. Under the appropriate conditions (0.13g/g [C8Tropine]pro, 35mg/g Cu(Ac)2, 20mg/g d,l-phenylalanine, 0.51g/g H2O and 0.30g/g K2HPO4), the enantiomeric excess value of phenylalanine in solid phase (mainly containing l-enantiomer) was 65%. Finally, the interaction mechanism was studied via 1D and 2D NMR. The results indicate that d-enantiomer of phenylalanine interacts more strongly with chiral ILs and Cu2+ based on the chiral ion-pairs space coordination mechanism, which makes it tend to remain in the top IL-rich phase. By contrast, l-enantiomer is transferred into the solid phase. Above chiral ionic liquids aqueous two-phase systems have demonstrated obvious resolution to racemic phenylalanine and could be promising alterative resolution approach for racemic amino acids in aqueous circumstance.

Progress in environmentally friendly ionic liquids aqueous two-phase systems

Aqueous two-phase systems(ATPSs) were usually formed as a result of mutual incompatibility of two polymers or one polymer and one salt above a certain concentration. ATPSs have advantages over conventional extraction systems using organic solvents,since the bulk of both phases consists of water. Ionic liquids(ILs) are liquid salts at the temperatures below boiling point of water. The particular interest is their highly tunable properties by varying the chemical structures of the ions comprised. Thus,by the rational design of cation and anion,an IL with desired characteristics can be created for a particular application. In 2003,the excellent ability of ILs to induce ATPSs was demonstrated in the presence of inorganic salts. Due to their high water content and no use of volatile compounds,the ILs-based ATPSs have been used to extract/separate amino acids,drugs,low molecular mass compounds,radiological isotopes,proteins and enzymes. However,it is known that among a large number of IL-based ATPSs,toxic and poorly biodegradable ILs have been widely used. On the other hand,high concentrations of inorganic salts are always used in the ILs-based ATPSs. This will produce a great amount of highly salty water in the applications,thus resulting in environmental problems. In this paper,environmentally friendly IL-based ATPSs,such as anion functionalized IL-salt ATPSs,IL-sugar ATPSs,IL-polymer ATPSs and CO2 induced ATPSs were systematically analyzed and reviewed. Among these ATPSs,anion functionalized ILs were used to replace poorly biodegradable imidazolium or pyridinium halide ILs,and high concentrations of inorganic salts were replaced by some new phase-forming materials,such as sugars,polymers and CO2 induced organic amines. From the viewpoint of sustainable chemistry,the researches described above could not completely solve the environmentally friendly problems of IL-based ATPSs,however,these innovative achievements would play an important role in the development of environmentally friendly IL-based ATPSs. Finally,challenges in the research and development of environmentally friendly IL-based ATPSs were discussed and suggestions for further research were provided.

Extraction and mechanistic investigation of trace dibutyl phthalate using an ionic liquid aqueous two-phase system

An ionic liquid aqueous two-phase system was applied to extract trace dibutyl phthalate from water samples together with the HPLC-UV method.

Extraction of Lysozyme by Hydroxyl-Functionalized Ionic Liquid Aqueous Two-Phase System

Extraction of Lysozyme by Hydroxyl-Functionalized Ionic Liquid Aqueous Two-Phase System

利用双水相分离回收离子液体的研究进展

The investigation on the separation and recovery of ionic liquids from water would be of great importance in reducing environmental impact of ionic liquids, enhancing their utilization efficiency, decreasing their industrial cost and promoting their industrial application. In this review, we focused our attention on the research progress in the recovery of ionic liquids by using salt + ionic liquid aqueous two-phase systems, sugar + ionic liquid aqueous two-phase systems, polymer + ionic liquid aqueous two-phase systems, and carbon dioxide induced aqueous two-phase systems. The main influence factors on the recovery of the ionic liquids were analyzed, and advantages and disadvantages of different ionic liquid aqueous two-phase systems were evaluated. The development in the ionic liquid recovery was prospected and the challenges were stressed.

Facile and effective separation of polysaccharides and proteins from Cordyceps sinensis mycelia by ionic liquid aqueous two-phase system

An ionic liquid aqueous two-phase system (ILATPS) based on the hydrophilic ionic liquid 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and inorganic salts (K3PO4 and K2HPO4) was employed to separate Cordyceps sinensis polysaccharides (CSPS) and proteins by a single-step procedure. The maximum extraction efficiencies of CSPS and proteins were 89.4% and 88.2%, respectively, as obtained with the [C4mim]Cl/K3PO4 system at 25°C and pH 13.0 under optimal conditions. The partially purified CSPS obtained from the bottom salt-rich phase comprised glucose, mannose, and galactose at a molar ratio of 10:3.5:1. The backbone of CSPS mainly comprised α-1,4-linked-d-glucose residues with a molecular weight of 2.3×107Da. The results of this study suggest that ILATPS is an efficient and environmentally friendly system that will highlight novel possibilities in the large-scale separation and purification of active polysaccharides from fungi or mushrooms.

Design of functional guanidinium ionic liquid aqueous two-phase systems for the efficient purification of protein

A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been devised and synthesized based on 1,1,3,3-tetramethylguanidine. The structures of the ionic liquids (ILs) were confirmed by 1H nuclear magnetic resonance (1H NMR) and 13C nuclear magnetic resonance (13C NMR) and the production yields were all above 90%. Functional guanidinium ionic liquid aqueous two-phase systems (FGIL-ATPSs) have been first designed with these functional guanidinium ILs and phosphate solution for the purification of protein. After phase separation, proteins had transferred into the IL-rich phase and the concentrations of proteins were determined by measuring the absorbance at 278nm using an ultra violet visible (UV–vis) spectrophotometer. The advantages of FGIL-ATPSs were compared with ordinary ionic liquid aqueous two-phase systems (IL-ATPSs). The proposed FGIL-ATPS has been applied to purify lysozyme, trypsin, ovalbumin and bovine serum albumin. Single factor experiments were used to research the effects of the process, such as the amount of ionic liquid (IL), the concentration of salt solution, temperature and the amount of protein. The purification efficiency reaches to 97.05%. The secondary structure of protein during the experimental process was observed upon investigation using UV–vis spectrophotometer, Fourier-transform infrared spectroscopy (FT-IR) and circular dichroism spectrum (CD spectrum). The precision, stability and repeatability of the process were investigated. The mechanisms of purification were researched by dynamic light scattering (DLS), determination of the conductivity and transmission electron microscopy (TEM). It was suggested that aggregation and embrace phenomenon play a significant role in the purification of proteins. All the results show that FGIL-ATPSs have huge potential to offer new possibility in the purification of proteins.

Enantioseparation of mandelic acid enantiomers in ionic liquid aqueous two-phase extraction systems

AbstractIn the past decade, ionic liquids have received great attention owing to their potential as green solvent alternatives to conventional organic solvents. In this work, hydrophobic achiral ionic liquids (1-butyl-3-methylimidazolium-hexafluorophosphate([bmim][PF6]), 1-octyl-3-methylimidazolium tetrafluoroborate([omim][BF4])) were used as solvents in chiral liquid-liquid extraction separation of mandelic acid (MA) enantiomers with β-cyclodextrin (β-CD) derivatives as hydrophilic chiral selectors preferentially forming complexes with (R)-enantiomers. Factors affecting the separation efficiency were optimised, namely the type of the extraction solvents and β-CD derivatives, concentrations of the β-CD derivatives and MA enantiomers, pH, and temperature. Excellent enantioseparation of MA enantiomers was achieved in the ionic liquid aqueous two-phase extraction systems under the optimal conditions of pH 2.5 and temperature of 5°C with the maximum enantioselectivity (α) of 1.74. The experimental results demonstrated that the ionic liquid aqueous two-phase extraction systems with a β-CD derivative as the chiral selector have a strong chiral recognition ability, which might extend the application of ionic liquids in chiral separation.

Relative hydrophobicity between the phases and partition of cytochrome-c in glycine ionic liquids aqueous two-phase systems

In this work, glycine ionic liquids tetramethylammonium glycine ([N1111][Gly]), tetraethylammonium glycine ([N2222][Gly]), tetra-n-butylammonium glycine ([N4444][Gly]), tetra-n-butylphosphonium glycine ([P4444][Gly]) and tetra-n-pentylammonium glycine ([N5555][Gly]) were synthesized and used to prepare aqueous two-phase systems (ATPSs) in the presence of K2HPO4. Binodal curves of such ATPSs and partition coefficients of a series of dinitrophenylated (DNP) amino acids in these ATPSs were determined at 298.15K to understand the effect of cationic structure of the ionic liquids on the phase-forming ability of glycine ionic liquids, relative hydrophobicity between the phases in the ionic liquids ATPSs, and polarity of the ionic liquids-rich phases. With the attempt to correlate the relative hydrophobicity of the phases in the ATPSs with their extraction capability for proteins, partition coefficients of cytochrome-c in the ATPSs were also determined. It was shown that partition coefficients of cytochrome-c were in the range from 2.83 to 20.7 under the studied pH conditions. Then, hydrophobic interactions between cytochrome-c and the ionic liquid are suggested to be the main driving force for the preferential partition of cytochrome-c in the glycine ionic liquid-rich phases of the ATPSs. Result derived from polarity of the ionic liquids-rich phases supports this mechanism.

Extraction of proteins with ionic liquid aqueous two-phase system based on guanidine ionic liquid

Eight kinds of green ionic liquids were synthesized, and an ionic liquid aqueous two-phase system (ILATPS) based on 1,1,3,3-tetramethylguandine acrylate (TMGA) guanidine ionic liquid was first time studied for the extraction of proteins. Single factor experiments proved that the extraction efficiency of bovine serum albumin (BSA) was influenced by the mass of IL, K2HPO4 and BSA, also related to the separation time and temperature. The optimum conditions were determined through orthogonal experiment by the five factors described above. The results showed that under the optimum conditions, the extraction efficiency could reach up to 99.6243%. The relative standard deviations (RSD) of extraction efficiencies in precision experiment, repeatability experiment and stability experiment were 0.8156% (n=5), 1.6173% (n=5) and 1.6292% (n=5), respectively. UV–vis and FT-IR spectra confirmed that there were no chemical interactions between BSA and ionic liquid in the extraction process, and the conformation of the protein was not changed after extraction. The conductivity, DLS and TEM were combined to investigate the microstructure of the top phase and the possible mechanism for the extraction. The results showed that hydrophobic interaction, hydrogen bonding interaction and the salt out effect played important roles in the transferring process, and the aggregation and embrace phenomenon was the main driving force for the separation. All these results proved that guanidine ionic liquid-based ATPSs have the potential to offer new possibility in the extraction of proteins.

Liquid–liquid equilibrium phase behavior of iminazolium-based ionic liquid aqueous two-phase systems composed of 1-alkyl-3-methyl imidazolium tetrafluoroborate and different electrolytes ZnSO4, MgSO4 and Li2SO4 at 298.15 K: Experimental and correlation

Ionic liquid-based aqueous two-phase systems offer an attractive alternative to volatile organic solvents in liquid–liquid extraction. In this work, the phase diagrams of the 1-alkyl-3-methyl imidazolium tetrafluoroborate ([C2mim]BF4/[C4mim]BF4)+ZnSO4/MgSO4/Li2SO4+H2O ATPSs were determined at 298.15K. Three empirical equations were used to correlate the binodal data and the optimum equation was selected. The effective excluded volume (EEV) values obtained from the binodal model for these systems were determined. The EEV and the binodal curves plotted in molality both indicate that the salting-out abilities of the three salts follow the order: ZnSO4>MgSO4>Li2SO4, while the phase-separation abilities of the investigated ILs are in the order of [C4mim]BF4>[C2mim]BF4. Finally, the liquid–liquid equilibrium data were successfully correlated by the Othmer-Tobias and Bancroft equations, meanwhile the slope of tie line increased with an increase in cation alkyl chain length.

Selective separation of aliphatic and aromatic amines with CO2 switchable ionic liquids aqueous two-phase systems

In many practical processes, separation of aliphatic amines from aromatic amines in water is imperative to obtain the desired products. In this work, a novel strategy was proposed for selective separation of aliphatic amines from aromatic amines with CO2 switchable ionic liquids (ILs) aqueous two-phase systems (ATPSs). It was shown that upon introduction of CO2 into an aqueous solution containing the IL, aliphatic amine and aromatic amine at 25 °C and atmospheric pressure, an ATPS could be formed with an IL-rich top phase and an ammonium-salt-rich bottom phase. Under these circumstances, the aromatic amine was largely partitioned in the IL-rich phase, while the aliphatic amine was transformed into the ammonium salt by the reaction with CO2. Thus the aliphatic amine was well separated from the aromatic amine in aqueous solution. The distribution ratios of aromatic amines between the two phases were found to increase with increasing hydrophobicity of ILs and aromatic amines, pKa values of aliphatic amines and tie-line length of the systems. Moreover, aliphatic amines retained in the ammonium-salt-rich phases were regenerated by bubbling N2 under heating, while aromatic amines in the IL-rich phases were removed by simple steam distillation. The recovery efficiency for aliphatic amines was as high as 99.0%. The regenerated ILs could then be reused in the next separation process, and no decrease in the distribution ratios of aromatic amines was observed after six cycles.

Extraction and separation of proteins by ionic liquid aqueous two-phase system

A satisfactory protocol of protein extraction and separation has been established based on the ionic liquid aqueous two-phase system (IL-ATPS) for the purification of bioactive substances. Compared with the effects of eight different ionic liquids, 1-octyl-3-methylimidazolium bromide ([omim][Br]) was selected as the suitable ionic liquid. Based on the single-factor experiment, an initial serial investigative test was used to identify the optimal conditions of the extraction. Owing to their different isoelectric points, bovine serum albumin (BSA), hemoglobin (Hb) and lysozyme (Lys) were used to determine the effect of pH value on the protein extraction. Trypsin (Try) was used to confirm the protein activity. The linearity for analyzing BSA, Hb, Try and Lys was in the concentration range of 0.05-1.00 mgml(-1), 0.025-1 mgml(-1), 0.01-1.00 mgml(-1) and 0.01-1.00 mgml(-1), respectively, with a correlation coefficient of between 0.9985 and 0.9999. Limits of detection (LODs) were 16.47-7.02 μgml(-1) and RSDs of inter-day stability were less than 2.9%. Repeatability and precision were respectively lower than 5.3% and 1.1%. Under the optimum conditions, the average recoveries of BSA, Hb, Try and Lys were 90.5%, 94.5%, 92.7% and 93.8% and the obtained RSDs were 1.19%, 1.23%, 1.34% and 1.04%, respectively. According to UV spectra, conductivity, dynamic light scattering (DLS), and transmission electron microscope (TEM) images, the cluster phenomenon originating from IL itself or combined with protein was evaluated. As the driving forces which are involved in the partitioning of protein between the IL-rich phase and the phosphate phase, the cluster phenomenon could, in principle, be applied to a variety of different samples and exhibited potential value.

Optimization of partitioning process parameters of chloramphenicol in ionic liquid aqueous two-phase flotation using response surface methodology

Ionic liquid aqueous two-phase flotation (ILATPF) is a green and effective separation and purification method, which combines solvent sublation and ionic liquid aqueous two-phase extraction system. This investigation attempts to study and optimize the partitioning conditions of chloramphenicol (CAP) in ILATPF. An experimental design of response surface methodology (RSM) was used to evaluate the influence of the variables, including the type of ionic liquid (IL), K2HPO4 concentration, flotation time and gas flow rate on CAP flotation. Quadratic polynomial models were adjusted to the data to predict the behavior of two responses, namely the partition coefficient (K) and sublation efficiency (E) of CAP. The optimal flotation conditions were found using [C6mim]Cl, 0.74 g/mL K2HPO4, 50 min flotation time and 50 mL/min gas flow rate, which ensured K = 405.71 and E = 93.16 %. It was observed that the effect of the four factors on K and E of CAP was flotation time > gas flow rate > the type of IL > K2HPO4 concentration. The ILATPF was proved effective for CAP separation in aqueous phase, and RSM was revealed to be an appropriate and powerful tool for experimental design of CAP separation by ILATPF.