Ionic Liquid-based Aqueous Two-phase System Research Articles

Extraction of lutein by aqueous two-phase system including both cholinium and imidazolium-based ionic liquids from wet microalgae

Lutein is the main component of macular and retinal pigment so that it is essential for eye health. In addition, lutein is also related to various metabolic processes in the human body with strong antioxidant properties. The green extraction of lutein in wet microalgae is critical for the further applications as nutraceuticals and pharmaceuticals. Ionic liquid-based aqueous two-phase system (ATPS) is a green approach for multiple product extraction from microalgae. In this study, the extraction performances of ATPS composed of four different cholinium-based compounds (choline geranate, choline chloride, choline dihydrogen citrate and choline bitartrate) and polyethylene glycol 400 (PPG400) were compared. The choline dihydrogen citrate (Ch DHcit) showed a better extraction ability of lutein than other cholinium-based ILs. After optimizing the addition of cholinium-based ILs and PPG400, the ATPS with the best composition (PPG400: Ch Dhcit: water: algal suspension = 42:26:22:10 wt%) was applied to the extraction of lutein from wet Chlorella sp. Six imidazolium-based ionic liquids (1-ethyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazole chloride, 1-hexyl-3-methylimidazole chloride and 1-hexyl-3-methylimidazolium bromide) were compared as an adjuvant for the lutein extraction from wet Chlorella sp. The introduction of a small amount of 1-ethyl-3-methylimidazole chloride ([C2mim]Cl) improved the extraction efficiency of lutein increased by 9.98 %. In the multiple-times extraction process, the total extraction efficiency of three times distribution reached 102.61 %. This paper provides a new approach to the extraction of lutein from algal biomass.

Palladium(II) extraction from acidic chloride media using an ionic liquid-based aqueous two-phase system (IL-ATPS) in the presence of dipotassium hydrogen phosphate salting-out agent and reductive stripping with hydrazine hydrate to recover palladium metal

Aqueous two-phase systems (ATPSs) based on ionic liquids (ILs) are efficient and green extraction systems. In this study, ATPSs consisted of three hydrophilic imidazolium-based ionic liquids ([C4mim]Br, [C6mim]Br, and [C8mim]Br) with phosphate, which were employed for Pd(II) extraction in acidic solutions. The obtained results showed that IL-ATPSs exhibited excellent Pd(II) extraction performance in acidic media, and Pd(II) was concentrated into ionic liquid rich upper phase. Palladium(II) extraction efficiencies of the three imidazolium-based ILs in acidic media were >98%, and the order of extraction efficiencies was: [C4mim]Br > [C6mim]Br > [C8mim]Br. Palladium(II) concentrated in IL-rich phase was recovered via direct reduction with hydrazine hydrate. Fourier transform infrared spectrometer (FT-IR) and mass spectrometry characterization indicated that Pd(II) migration into IL-rich phase followed an ion-exchange mechanism. Furthermore, transmission electron microscopy showed that “oil-in-water” micelles were formed during Pd(II) extraction.

Assessment of ionic liquid-based aqueous two-phase system abilities to remove sulfonamide antibiotics from the aquatic environment

Assessment of ionic liquid-based aqueous two-phase system abilities to remove sulfonamide antibiotics from the aquatic environment

Fractionation of phycocyanin and carbohydrate from Spirulina platensis using ionic liquid-based aqueous two-phase system

Microalgae have gained considerable attention due to their high-value biomolecules and potential applications in the pharmaceutical, food, medical and cosmeceutical field. However, the conventional biorefinery process of microalgae are costly, energy-intensive, and time-consuming. Aqueous two-phase system (ATPS) has emerged as a potential technique for the separation and fractionation of biomolecules in the biorefinery field. This study proposed the application of ionic liquid (IL) based ATPS for the fractionation of high-value phycocyanin and carbohydrates from a crude extract of Spirulina platensis.The biomass was first lysed by a high-speed homogenization with a solid to liquid ratio (S/L) of 1:10 and an operation time of 5 min to achieve optimum yields of multiple products. Next, the feasibility of several IL-based ATPS with phosphate/citrate buffer was evaluated by investigating the effects of cation, anion, and alkyl chain’s length of ILs. Among the IL-based ATPS, the system comprising of 1-butyl-1-methylpyrrolidinium dicyanamide and citrate buffer demonstrated the optimum phycocyanin extraction efficiency of 83.26 ± 0.05% at the top phase and a concurrent recovery of 73.89±0.06% carbohydrate at the bottom phase. In this work, the IL-based ATPS performed better than conventional polymer-based ATPS. This work suggests that IL-based ATPS allows efficient fractionation of phycocyanin and carbohydrates.

Distribution of pigments in the aqueous two-phase system formed with piperazinium-based ionic liquid and anionic surfactant

In this work, phase behaviors and pigment extraction performance of the ionic liquid-based aqueous two-phase system (IL-ATPS) formed by 1-ethylpiperazinium tertrafluoroborate ([C2pi][BF4]) + sodium dodecyl sulfonate (SDS) and 1-phenylpiperazinium tertrafluoroborate ([Phpi][BF4]) + sodium dodecyl benzene sulfonate (SDBS) are investigated. Phase composition of ATPS is determined, revealing ion exchange between conjugated phases. Mixing the piperazinium-based IL with the anionic surfactant produces a weakly acidic environment of ATPS which is suitable for the separation of curcumin. The influences of surfactant/IL mass ratio, pigment concentration and temperature on extraction efficiency and distribution coefficient are evaluated. The separation mechanism of ATPS is further explored by DLS, TEM and FTIR. The packing effect induced by the re-assembly of micelles formed mainly by IL cations and surfactant anions are the driving force for the preferable separation of curcumin, while carmine distributes in both phases with similar concentrations due to its high water solubility.

Investigating the binding measurements of human α-acid glycoprotein with chlorambucil and dacarbazine in the presence of imidazolium based -ionic liquid by affinity capillary electrophoresis

Human alpha (α1)-acid glycoprotein (AGP) is an acute phase protein whose plasma concentration increases several-folds in the presence of various diseases. The variability in AGP plasma concentration is expected to have a huge impact on the drug binding equilibrium. Therefore, a precise measurement of AGP-drug binding is of great demand for drug development. In the current study, an ionic liquid-based aqueous two-phase system combined with affinity capillary electrophoresis (ILATPS/ACE) was utilised in order to improve the accuracy of AGP-drug binding analysis through the measurements of electrophoretic mobilities. The utilisation of ILATPS has shown to have a positive impact on the stability of AGP activity solution during the storage for an extended period of time. In addition, the effect of various alkyl chains (C2-C10) of imidazolium-based ILs with concentrations ranging between 10.00 and 1000.0 μmol L−1 on the AGP binding with the anti-cancer drugs chlorambucil (CHL) and dacarbazine (DAC) was examined by the system developed (ILATPS/ACE). A 100.00 μmol L−1 1-ethyl-3-methylimidazolium chloride (EMImCl) prepared in the physiological buffer conditions containing AGP (5.00–100.00 µmol L−1) has provided an accurate apparent binding constant of 1.99 ± 0.11 and 6.95 ± 0.14 L mmol−1 with CHL and DAC respectively. Apart from the ACE analysis, EMImCl/phosphate buffer solution was found to be a distinguished system that could lengthen the stability of AGP activity for a period of time reaching 90 days during the solution storage at 4.00 °C. This effect is thought to be due to the easy conversion of one-phase EMImCl/phosphate buffer/AGP at the ambient lab temperature into the two-phase solution at refrigerator temperature, 4.00 °C, and vice versa. Therefore, the ILATP/ACE system could be used to enhance the accuracy for other AGP-drug bindings with a fast, easy to use, and cost-effective analysis.

Ionic Liquid-based Aqueous Two-phase System Coupled With Flame Atomic Absorption Spectrometry for the Preconcentration and Determination of Copper in Water Samples

Ionic Liquid-based Aqueous Two-phase System Coupled With Flame Atomic Absorption Spectrometry for the Preconcentration and Determination of Copper in Water Samples

Lanthanum and Cerium Separation Using an Aqueous Two-Phase System with Ionic Liquid

In this work, an organic solvent-free extraction approach was developed to selectively separate La from Ce using an ionic liquid-based aqueous two-phase system (ILATPS). ILATPSs composed of 1-ethyl-3-methylimidazolium chloride, C2MIMCl, K2CO3 (or K2HPO4), and water at 283, 298, and 313 K were obtained. The biphasic region decreased slightly with increasing temperature. These ILATPSs were applied for the separation of lanthanum from cerium. Some parameters that affect the separation of La and Ce, such as the alkyl chain length of the imidazolium cation, the type of electrolyte, and extractant concentration, were investigated. The best conditions for separation were achieved using the ILATPS formed by C2MIMCl + K2CO3 + H2O and 40.4 mmol kg–1 alizarin red S (as an extractant). The extraction percentage for La was 100%, whereas the extraction for Ce was 5.4%, yielding a separation factor between La and Ce equal to 2620.

A green separation strategy for neodymium (III) from cobalt (II) and nickel (II) using an ionic liquid-based aqueous two-phase system

It is significant to develop sustainable strategies for the selective separation of rare earth from transition metals from fundamental and practical viewpoint. In this work, an environmentally friendly solvent extraction approach has been developed to selectively separate neodymium (III) from cobalt (II) and nickel (II) by using an ionic liquid-based aqueous two phase system (IL-ATPS). For this purpose, a hydrophilic ionic liquid (IL) tetrabutylphosphonate nitrate ([P4444][NO3]) was prepared and used for the formation of an ATPS with NaNO3. Binodal curves of the ATPSs have been determined for the design of extraction process. The extraction parameters such as contact time, aqueous phase pH, content of phase-formation components of NaNO3 and the ionic liquid have been investigated systematically. It is shown that under optimal conditions, the extraction efficiency of neodymium (III) is as high as 99.7%, and neodymium (III) can be selectively separated from cobalt (II) and nickel (II) with a separation factor of 103. After extraction, neodymium (III) can be stripped from the IL-rich phase by using dilute aqueous sodium oxalate, and the ILs can be quantitatively recovered and reused in the next extraction process. Since [P4444][NO3] works as one of the components of the ATPS and the extractant for the neodymium, no organic diluent, extra etractant and fluorinated ILs are used in the separation process. Thus, the strategy described here shows potential in green separation of neodymium from cobalt and nickel by using simple IL-based aqueous two-phase system.

Ionic Liquid-Based Ultrasonic-Assisted Extraction of Secoisolariciresinol Diglucoside from Flaxseed (Linum usitatissimum L.) with Further Purification by an Aqueous Two-Phase System.

In this work, a two-step extraction methodology of ionic liquid-based ultrasonic-assisted extraction (IL-UAE) and ionic liquid-based aqueous two-phase system (IL-ATPS) was developed for the extraction and purification of secoisolariciresinol diglucoside (SDG) from flaxseed. In the IL-UAE step, several kinds of ILs were investigated as the extractants, to identify the IL that affords the optimum extraction yield. The extraction conditions such as IL concentration, ultrasonic irradiation time, and liquid–solid ratio were optimized using response surface methodology (RSM). In the IL-ATPS step, ATPS formed by adding kosmotropic salts to the IL extract was used for further separation and purification of SDG. The most influential parameters (type and concentration of salt, temperature, and pH) were investigated to obtain the optimum extraction efficiency. The maximum extraction efficiency was 93.35% under the optimal conditions of 45.86% (w/w) IL and 8.27% (w/w) Na2SO4 at 22 °C and pH 11.0. Thus, the combination of IL-UAE and IL-ATPS makes up a simple and effective methodology for the extraction and purification of SDG. This process is also expected to be highly useful for the extraction and purification of bioactive compounds from other important medicinal plants.

Chiral separation of α-cyclohexylmandelic acid enantiomers using ionic liquid/salt aqueous two-phase system

AbstractIn this paper, an ionic liquid-based aqueous two-phase system (ILATPS) was applied to the chiral separation of α-cyclohexylmandelic acid (α-CHMA) enantiomers with hydroxypropyl-β- cyclodextrin (HP-β-CD) as the chiral selector. Several influencing parameters were investigated including the types and concentration of ionic liquids, the amount of phase-forming salt, temperature, mixing time, pH, and the content of HP-β-CD. The results showed that not all ILATPS had the ability to chirally recognise the selected enantiomers and that [C

Recovery of Bacillus cereus cyclodextrin glycosyltransferase using ionic liquid-based aqueous two-phase system

Ionic liquids-based aqueous two-phase system (ILATPS) offers immediate phase separation and thus reduces the overall processing time, is significantly advantageous as compared to conventional ATPS such as polymer/polymer ATPS and polymer/salt ATPS. In this study, ILATPSs composed of imidazolium-based ionic liquid (IL) and salt were experimentally evaluated for their efficiencies in recovering Bacillus cereus cyclodextrin glycosyltransferase (CGTase) from fermentation broth. The phase-forming behavior of 1-ethyl-3-methylimidazolium tetrafluroborate, (Emim)BF4/sodium citrate ILATPS and (Emim)BF4/sodium carbonate ILATPS were first studied by constructing the binodal curves. Effects of the ILs concentration, pH value, feedstock loading, and addition of sodium chloride (NaCl) on the recovery of CGTase in ILATPS were investigated. The optimum conditions for the recovery of CGTase were obtained in an ILATPS consisting of 35% (w/w) (Emim)BF4, 18% (w/w) sodium carbonate and 3% (w/w) NaCl. Experimental results showed that 78% of CGTase could be recovered in the IL-rich phase in single-step purification with a purification fold (PF) of 15.4. The high PF indicates that this ILATPS is feasible to be applied in the recovery and separation of CGTase from the fermentation broth.

Determination of sunset yellow and tartrazine in food samples by combining ionic liquid-based aqueous two-phase system with high performance liquid chromatography.

We proposed a simple and effective method, by coupling ionic liquid-based aqueous two-phase systems (IL-ATPSs) with high performance liquid chromatography (HPLC), for the analysis of determining tartrazine and sunset yellow in food samples. Under the optimized conditions, IL-ATPSs generated an extraction efficiency of 99% for both analytes, which could then be directly analyzed by HPLC without further treatment. Calibration plots were linear in the range of 0.01–50.0 μg/mL for both Ta and SY. The limits of detection were 5.2 ng/mL for Ta and 6.9 ng/mL for SY. This method proves successful for the separation/analysis of tartrazine and sunset yellow in soft drink sample, candy sample, and instant powder drink and leads to consistent results as obtained from the Chinese national standard method.

Ionic liquids as surfactants in micellar liquid chromatography

This paper is devoted to application of ionic liquids as surfactants in LC of organic compounds, derivatives of 1,4-thiosemicarbazides. According to HPLC requirements the most advantageous conditions such as transparency for ultraviolet light, low CMC, additional inorganic salt additives, and appropriate organic solvent were established. The CMC was determined using conductivity measurements. Suitability of two different stationary phases: RP-C18 and cyanopropyl bonded phase was examined under micellar conditions. Chosen ionic liquid surfactant was compared to common traditional amphiphilic reagent - SDS. Elaborated on chromatographic micellar conditions were tested as a pilot technique for prediction of distribution coefficients of organic analytes in ionic liquid-based aqueous two-phase system.

Investigation of a phosphate/1-butyl-3-methylimidazolium trifluoromethanesulfonate/water system for the extraction of 1,3-propanediol from fermentation broth

The recovery of 1,3-propanediol from fermentation broth is challenging because of its high polarity and high boiling point. Extraction is an attractive alternative to the commonly used distillation process, which is very energy intensive and thus costly. Due to the low solubility of 1,3-propanediol in organic solvents, extraction has not yet been considered. Ionic liquid-based aqueous two-phase systems could constitute an alternative extraction system for the purification of 1,3-propanediol and are therefore investigated in this study. The distribution coefficient of 1,3-propanediol and the selectivity for it over the by-products of the fermentation, i.e., acetic acid and butyric acid, are determined in different ionic liquid-based aqueous two-phase systems. Based on these results, the ionic liquid-based aqueous two-phase system, phosphate/1-butyl-3-methylimidazolium trifluoromethanesulfonate (Im4,1 CF3SO3), is chosen for further investigation. The effects of the temperature, pH and Im4,1 CF3SO3, phosphate and 1,3-propanediol mass fractions on the phase diagram are examined. Furthermore, the influence of the fermentation by-products on the liquid–liquid equilibrium is determined. All experiments were performed using synthetic media to identify the effects of the process parameters independently from non-ideality incorporated through the use of real fermentation broth. To verify that this approach leads to correct results, results obtained with fermentation broth were compared to those obtained with synthetic media prior to these experiments. The recovery and potential re-use of the ionic liquid, Im4,1 CF3SO3, is finally analysed by repeating some of the experiments with recovered ionic liquid.

Choline-like ionic liquid-based aqueous two-phase extraction of selected proteins

In this paper, an ionic liquid-based aqueous two-phase system (ATPs) has been developed for the effective extraction of bovine serum albumin (BSA). Compared with the effects of three different ionic liquids used in an aqueous two-phase system, a choline-like ionic liquid was selected as the suitable solution for bovine serum albumin. Extraction efficiencies of BSA were found to be dependant on the temperature, time, IL mass and the salt content. Based on single-factor experiments, these significant operating parameters of the ILs-ATP were respectively optimized. Experimental results show that 92.03–100.03% of the proteins could be extracted into the ionic liquid-rich phase in a single-step extraction. Repeatability, precision and stability experiments were investigated and the RSDs are lower than 2.3%, 1.7% and 4.7% respectively. Experiments indicated that intermolecular forces, the micelle phenomenon and the salting-out effect play important roles in the transfer process, and the aggregation phenomenon was the main driving force for the separation. Conformation of the protein was not affected after extraction into the upper ionic liquid-rich phase according to the determination by UV-visible (UV-vis), fluorescence spectra, dynamic light scattering (DLS), Fourier transform infrared (FT-IR) spectroscopy and TEM. It is suggested that the method of choline-like ILs-based ATPs for the selective separation of protein would have potential applications in bio-analysis and bio-separation.

Selective extraction and determination of vitamin B12 in urine by ionic liquid-based aqueous two-phase system prior to high-performance liquid chromatography

A rapid and simple extraction technique based on aqueous two-phase system (ATPS) was developed for separation and enrichment of vitamin B12 in urine samples. The proposed ATPS-based method involves the application of the hydrophilic ionic liquid (IL) 1-hexyl-3-methylimidazolium chloride and K2HPO4. After the extraction procedure, the vitamin B12-enriched IL upper phase was directly injected into the high performance liquid chromatography (HPLC) system for analysis. All variables influencing the IL-based ATPS approach (e.g., the composition of ATPS, pH and temperature values) were evaluated. The average extraction efficiency was 97% under optimum conditions. Only 5.0mL of sample and a single hydrolysis/deproteinization/extraction step were required, followed by direct injection of the IL-rich upper phase into HPLC system for vitamin B12 determination. A detection limit of 0.09μgmL−1, a relative standard deviation (RSD) of 4.50% (n=10) and a linear range of 0.40–8.00μgmL−1 were obtained. The proposed green analytical procedure was satisfactorily applied to the analysis of samples with highly complex matrices, such as urine. Finally, the IL-ATPS technique could be considered as an efficient tool for the water-soluble vitamin B12 extraction.

Simultaneous extraction and purification of aloe polysaccharides and proteins using ionic liquid based aqueous two-phase system coupled with dialysis membrane

In this paper, an ionic liquid based aqueous two-phase system (ILATPS) was employed in simultaneous extraction and purification of aloe polysaccharides (APS) and proteins by a single-step procedure. Parameters affecting the extraction efficiency were investigated in detail, such as type and concentration of phase-forming salt, temperature, pH, inorganic electrolyte, etc. Under the optimal extraction conditions, APS can be extracted into salt-rich phase with high extraction efficiency, while majority proteins and other impurities were extracted into IL-rich phase. APS were further purified using a dialysis membrane to remove the salt and IL. In addition, the monosaccharide constitutes of APS were analyzed by a HPLC method. The purity of the final product was demonstrated by a thermogravimetric analysis (TGA). IL in IL-rich phase was recycled by a simple solvent extraction method using dichloromethane. Compared with other liquid–liquid extraction, ILATPS is much simpler and “greener”, it will open up new possibilities in the separation of other active ingredients in natural plants.

Thermodynamic studies of partitioning behavior of cytochrome c in ionic liquid-based aqueous two-phase system

The ionic liquid/aqueous two-phase extraction systems (ATPSs) based on imidazolium ionic liquids were used to extract cytochrome c. Effects of the alkyl chain length of the ionic liquid cations, concentration of potassium citrate, temperature and pH on the extraction efficiency have been investigated. The thermodynamic parameters (ΔGT°, ΔHT° and ΔST°) associated with Cyt-c partitioning in aqueous two phase systems were determined. Thermodynamic studies indicated that the partitioning of Cyt-c was driven by both hydrophobic and electrostatic interactions in the extraction process. Under the optimum conditions, experiment results showed that 94% of the cytochrome c could be extracted into the ionic liquid-rich phase in a one-step extraction. The structural characterization of Cyt-c in the IL ATPS was investigated by UV–vis and circular dichroism (CD) spectra. The results demonstrated that no direct bonding interaction observed between ionic liquid and cytochrome c, while the native properties of the cytochrome c were not altered. Compared with traditional liquid–liquid extractions based on toxic organic solvents, ionic liquid/aqueous two phase extraction offers clear advantages due to no use of volatile organic solvent and low consumption of imidazolium ionic liquids.

Driving forces of protein partitioning in an ionic liquid-based aqueous two-phase system

Extraction of catalytically active biomolecules using ionic liquid-based aqueous two-phase systems (IL-based ATPS) composed of the IL Ammoeng™ 110 and K 2HPO 4/KH 2PO 4 represents a powerful tool for the integration of several process steps into one unit operation within downstream processing. The technique can be used in order to combine the purification of active enzymes with the performance of enzyme-catalysed reactions. However, a fundamental understanding of the driving forces which are involved in the partitioning of proteins between the two phases is still lacking. By investigating the distribution of four model proteins at varying system characteristics of the IL-based ATPS, we found a combination of different interactions between the proteins and the ionic liquid to be responsible for the enrichment within the IL-containing upper phase. Among these, the proteins’ charge as well as the molecular weight is of major importance. Therefore, we propose the electrostatic interaction between the charged amino acid residues at a protein's surface and the positively charged IL-cation to be the main driving force of the extraction process. Based on these findings, a model for describing protein partitioning in IL-based ATPS was established and employed for predicting the partition coefficient of two further model proteins, pepsin and hemoglobin.