Surface Active Ionic Liquids Research Articles

Mini-review on Recent Advances in the Application of Surface-Active Ionic Liquids: Petroleum Industry Perspective

Ionic liquids have emerged as a promising new material for a wide range of industrial applications, because of their unique structures and properties. Ionic liquids possess exceptional properties such as chemical and thermal stability, negligible vapor pressure, or solvency power for different types of molecules. Ionic liquids find their application in different operations in petroleum industry. The purpose of this paper is to review previously published works on the application of the IL in various areas of the petroleum industry and related processes. A detailed discussion of various processes such as enhanced oil recovery, drilling fluids, gas hydrate, CO2 capture, and flow assurance has been provided. This in-depth discussion is intended to aid professional and researchers in understanding the present condition and planning for the future.

How multiple noncovalent interactions regulate the aggregation behavior of amphiphilic triblock copolymer/surface-active ionic liquid mixtures

Amphiphilic block copolymers/ionic liquids mixtures have been emerging as a new class of ‘chemical entity’ with numerous advanced applications. However, interaction mechanism governing the aggregation and the microstructure of aggregates are still far from full understanding. Herein, the role of noncovalent interactions in regulation of aggregation behaviors of mixtures of Pluronic F127 and surface-active ionic liquids, i.e. CnmimBr, CnPyBr and CnMPB is investigated by DLS, cryo-TEM, NMR and molecular dynamics simulation. The interaction modes between F127 and SAILs are remarkably dependent on the concentration and cationic headgroup of SAIL. At low SAIL concentration (<CMC), mixed micelles mainly composed of F127 with some SAIL cations embedded into micelles are formed, which was primarily driven by hydrophobic interaction. However, the residence of CnmimBr cations in micelles is quite different from that of CnPyBr and CnMPB cations due to its distinctive hydrogen bonding with PEO segment of F127. Upon further addition of SAILs (CSAILs > CMC), gradual disintegration of F127-rich micelles was observed due to the enhanced repulsive electrostatic force at micellar core-corona interface, accompanying with the re-formation of two types of micelles: one consisting of pure SAILs and one that SAIL micelles bound with F127 monomers via hydrogen bonding and/or hydrophobic interactions. This work provides new insight into the aggregation mechanism of these complex systems and will be helpful to rational tailoring innovative copolymers /IL-based system for specific applications.

Enhanced oil recovery with nanofluids based on aluminum oxide and 1-dodecyl-3-methylimidazolium chloride ionic liquid

Surface-active ionic liquids (SAILs) have multiplied the possibilities of surfactant enhanced oil recovery (EOR) methods. Among their multiple promising features, the possibility of functionalization and their stability at harsh conditions should be highlighted for the application. They have been successfully applied to increase oil recovery by improving crucial parameters such as: formulation stability, reduction of water–oil interfacial tension, and wettability. Recently, nanoparticles have attracted attention for EOR applications due to their capacity to modify the properties of rock surfaces. However, to date no research has been conducted on the combination of SAILs with nanoparticles for EOR. In this work, the combination of the SAIL 1-dodecyl-3-methylimidazolium chloride, [C12mim]Cl, with Al2O3 nanoparticles is proposed for EOR. Stable dispersions in brine were achieved, using the polymer polyvinylpyrrolidone (PVP) as a stabilizing agent, and characterized through density and dynamic viscosity measurements. According to stability and interfacial tension studies, a nanofluid consisting of 0.05 wt% [C12mim]Cl, 0.05 wt% Al2O3 and 1.0 wt% PVP, in brine (5.0 wt% NaCl) was proposed for EOR in carbonate reservoirs. The presence of nanoparticles reduced the adsorption of the surfactant-polymer formulation on carbonate rocks and changed the aged rock wettability from oil-wet to water-wet. An additional oil recovery of 10.4 %OOIP was achieved with the surfactant-polymer formulation, in comparison with 14.8 %OOIP obtained with the nanofluid.

Surface activity and phytotoxicity of morpholinium herbicidal ionic liquids

The use of efficient synthesis methods to obtain novel herbicidal ionic liquids (HILs) with biological activity is extremely important because it can eliminate certain negative environmental impacts. The authors of this work succeeded in the experiment, which resulted in the synthesis of 18 novel ionic liquids with high yields. Furthermore, a number of physicochemical and biological properties have been investigated, including surface activity, thermal analysis, and phytotoxicity. In addition, it was proven that morpholinium ionic liquids with phenoxyacid anions were more effective against cress than HILs previously studied in the literature. To the best of our knowledge, this is the first report of surface-active ionic liquids with herbicidal anions where leaf surfaces were used for analysis. An important aspect of this work was to compare the wettability of the surfaces of wheat leaves and weeds. Moreover, it was shown that using paraffin as a reference surface was not sufficient to describe the wetting properties of HILs. The research reported here proved that morpholinium ionic liquids were effective in wetting weed surfaces while they do not adversely affect wheat leaf surfaces. Our results could be significant for meeting the environmental challenges and agricultural demands of the future.

2-Ethylhexylsulfate Anion-based Surface-Active Ionic Liquids (SAILs) as temperature persistent electrolytes for supercapacitors

We report on a comparative study of three novel non-halogenated surface-active ionic liquids (SAILs), which contain a surface-active anion, 2-ethylhexyl sulfate ([EHS]−), and phosphonium or imidazolium cations: tetrabutylphosphonium ([P4,4,4,4]+), trihexyl(tetradecyl)phosphonium ([P6,6,6,14]+), and 1-methyl-3-hexylimidazolium ([C6C1Im]+). Thermal and electrochemical properties i.e., ionic conductivities at different temperatures and electrochemical potential windows of these SAILs were thoroughly studied. SAIL's electrochemical performance as electrolytes was also examined in a multi-walled carbon nanotubes (MWCNT)-based supercapacitor over a wide range of temperatures from 253 to 373 K. We observed that the electrode material in the supercapacitor cell with [C6C1Im][EHS] as an electrolyte has a higher specific capacitance (Celec in F g−1), a higher electric energy density (E in W h kg−1), and a higher electric power density (P in kW kg−1) as compared to the other studied SAILs, [P4,4,4,4][EHS], [P6,6,6,14][EHS] and [N8,8,8,8][EHS] (from our preceding study) in a temperature range from 253 to 373 K: At the scan rate of 2 mV s−1 a supercapacitor cell with a MWCNT-based electrode and [C6C1Im][EHS], [P4,4,4,4][EHS] and [P6,6,6,14][EHS] as electrolytes has the specific capacitance, Celec = 148, 90 and 47 F g−1 and the energy density, E = 82, 50 and 26 W h kg−1, respectively, when measured at 298 K. For the named three SAILs at the scan rate of 2 mV s−1, a two- to three-fold increase in the specific capacitance and the energy density values was measured at 373 K: Celec = 290, 198 and 114 F g−1 and E = 161, 110 and 63 Wh kg−1, respectively. The solution resistance (Rs), charge transfer resistance (Rct) and equivalent series resistance (ESR) all decreased two- to three-fold with an increase in temperature from 298 to 373 K. With the high specific capacitance and enhanced energy and power density and wider electrochemical potential window as compared to the molecular organic and aqueous electrolytes, these SAILs can be used for high-temperature electrochemical applications, such as high power and energy storage devices. In particular, up to now, [C6C1Im][EHS] and [P4,4,4,4][EHS] are the most appropriate candidates for such applications.

Surface-Active Ionic Liquid-Assisted Cloud Point Extraction for Pre-Concentration and Determination of Cobalt Ions in Pharmaceutical Preparations.

Herein we describe an efficient, simple, and precise micelle-mediated microextraction strategy based on the aggregation behavior of surface-active ionic liquids (SAILs) for the preconcentration and determination of cobalt ions in pharmaceutical preparations. Unlike the commonly used hydrophobic ionic liquids in IL-based microextraction methods, a water-soluble surface-active ionic liquid [1-hexadecyl 3-methylimidazolium chloride (C16MeImCl)] was used. A modified cloud point extraction (CPE) procedure based on the C16MeImCl-Triton X-114 mixed micellar system was proposed as an efficient extracting phase. A comparison of the analytical features of the extraction process with and without SAILs revealed the benefits of the proposed method. Advantages such as a wider linear range, lower detection limit, higher reproducibility, and improved extraction efficiency highlighted the proposed method over the conventional CPE method. These attractive specifications are due to the higher extraction efficiencies achieved in the presence of the SAIL and its favorable effects at the phase separation stage. Various parameters affecting the extraction efficiency were optimized by univariate and multivariate (Box-Behnken design) approaches. The calibration curve was obtained in the optimal experimental conditions with a linear range from 0.01 to 5.5 mg L-1 of cobalt ion concentration (R = 0.9992) and a detection limit of about 0.005 mg L-1. The RSD% for 10 replicate determinations of 1.0 mg L-1 Co was 0.9%. The proposed method was successfully applied to determine cobalt ions in vitamin B12 ampoules and tablets.

Ionic Liquid and Tween-80 Mixture as an Effective Dispersant for Oil Spills: Toxicity, Biodegradability, and Optimization.

Chemical dispersants are used extensively for oil spill remediation. Most of these dispersants are composed of a mixture of surfactants and organic solvents, which raises concerns about aquatic toxicity and environmental impact. In this study, the toxicity and biodegradability of an oil spill dispersant composed of the surface-active ionic liquid 1-butyl-3-methylimidazolium lauroyl sarcosinate [Bmim][Lausar] and Tween-80 were investigated. In addition, important environmental factors including salinity, temperature, and wave-mixing energy were optimized to obtain maximum dispersion effectiveness. The acute toxicity against zebrafish (Danio rerio) showed that the developed dispersant was practically non-toxic with a median lethal dose of more than 100 mg L–1 after 96 h. The dispersant also demonstrated outstanding biodegradability of 66% after 28 days. A model was developed using a response surface methodology that efficiently (R2 = 0.992) related the salinity, temperature, and wave-mixing energy of seawater to dispersion effectiveness. The system was then optimized, and a high dispersion effectiveness of 89.70% was obtained with an experimental error of less than 2%. Our findings suggest that the surface-active ionic liquid and Tween-80 mixture could be a viable alternative to toxic chemical dispersants for oil spill remediation.

Transdermal Delivery of Antigenic Protein Using Ionic Liquid-Based Nanocarriers for Tumor Immunotherapy.

Transdermal drug delivery systems (TDDSs) may be useful for preventing various diseases including cancer. However, the stratum corneum (SC) inhibits the permeation of foreign particles into the skin. To obtain an effective TDDS, we developed a protein-containing nanocarrier (PCNC) comprising an antigenic protein (ovalbumin/OVA) stabilized by a combination of surfactants, i.e., a lipid-based surface-active ionic liquid and Tween-80. The PCNC was lyophilized to remove water and cyclohexane and then dispersed in isopropyl myristate. It is biocompatible both in vitro and in vivo, and is suitable for use in a therapeutic TDDS. The skin permeability of the PCNC was significantly (p < 0.0001) enhanced, and the transdermal distribution and transdermal flux of the OVA delivery system were 25 and 28 times greater, respectively, than those of its aqueous formulation. The PCNC disrupted the order of lipid orientation in the skin's SC and increased intercellular protein delivery. It demonstrated effective antitumor activity, drastically (p < 0.001) suppressed tumor growth, increased mouse survival rates, and significantly (p < 0.001) stimulated the OVA-specific tumor immune response. The PCNC also increased the number of cytotoxic T cells expressing CD8 antibodies on their surfaces (CD8 + T-cells) in the tumor microenvironment. These findings suggest that PCNCs may be promising biocompatible carriers for transdermal antigenic protein delivery in tumor immunotherapy.

Unravelling the Interactions Prevailing in Mixed Micellar System of Surface-Active Ionic Liquid and Cationic Surfactant

The investigation of mixed micellar behavior of surface-active ionic liquid (SAIL) i.e. 1-butyl-3-methylimidazolium hexadecyl sulfate [C4mim][HS] with cationic surfactant cetyltrimethylammonium bromide (CTAB) has been done to explore the type of interactions prevailing in SAIL/Surfactant mixed system. Thus, the conductometric measurements are performed at (298.15, 308.15 and 318.15) K for various mole fractions of [C4mim][HS]. Different theoretical models like Clint, Rubingh, Motomura and Rodenas have been applied to understand mixed micellar behavior of SAIL/Surfactant mixed system. The value of critical micelle concentrations (cmc), micellar mole fraction based upon various models, ideal critical micelle concentrations (cmc*), interaction parameter (β) and thermodynamic parameters have been evaluated for the mixed systems. The variations of various parameters with respect to temperature and mole fractions give insight to sort of interactions present in studied system.

Micellization, surface activities, and thermodynamic studies on the ionic liquid in the presence of vitamins

Surface active ionic liquids (SAILs) are classified as a significant class of ionic surfactants that display superior surface properties compared to conventionally available ionic surfactants. The micellization properties of these liquids can be tailored in the presence of various additives (surfactants/drugs/vitamins/amino acids/carbohydrates). But there are few studies on the investigation of micellization of ionic liquid in the presence of vitamins. Considering this, the conductivity and surface tension measurements have been done to study the influence of vitamins (thiamine hydrochloride(ThHCl)/pyridoxine hydrochloride(PyHCl);) on the micellar and surface properties of ionic liquid [C15mim] [Br] at various concentrations (0.01, 0.05, and 0.1) mM and temperatures (298.15–318.15) K. The properties comprise determination of critical micelle concentration, micellization parameters, surface excess concentration, minimum area per molecule, and Gibbs free energy of adsorption. The main objective is to learn the interactions occurring between ionic liquids and these biomolecules along with the utilization of these ionic liquids in biomedical science, drug delivery, and bio industries.

Interfacial Properties, Wettability Alteration and Emulsification Properties of an Organic Alkali–Surface Active Ionic Liquid System: Implications for Enhanced Oil Recovery

Combinatory flooding techniques evolved over the years to mitigate various limitations associated with unitary flooding techniques and to enhance their performance as well. This study investigates the potential of a combination of 1-hexadecyl-3-methyl imidazolium bromide (C16mimBr) and monoethanolamine (ETA) as an alkali–surfactant (AS) formulation for enhanced oil recovery. The study is conducted comparative to a conventional combination of cetyltrimethylammonium bromide (CTAB) and sodium metaborate (NaBO2). The study confirmed that C16mimBr and CTAB have similar aggregation behaviors and surface activities. The ETA–C16mimBr system proved to be compatible with brine containing an appreciable concentration of divalent cations. Studies on interfacial properties showed that the ETA–C16mimBr system exhibited an improved IFT reduction capability better than the NaBO2–CTAB system, attaining an ultra-low IFT of 7.6 × 10−3 mN/m. The IFT reduction performance of the ETA–C16mimBr system was improved in the presence of salt, attaining an ultra-low IFT of 2.3 × 10−3 mN/m. The system also maintained an ultra-low IFT even in high salinity conditions of 15 wt% NaCl concentration. Synergism was evident for the ETA–C16mimBr system also in altering the carbonate rock surface, while the wetting power of CTAB was not improved by the addition of NaBO2. Both the ETA–C16mimBr and NaBO2–CTAB systems proved to form stable emulsions even at elevated temperatures. This study, therefore, reveals that a combination of surface-active ionic liquid and organic alkali has excellent potential in enhancing the oil recovery in carbonate reservoirs at high salinity, high-temperature conditions in carbonate formations.

A density functional theory study on the water aggregation behaviour of fatty acid-based anionic surface active ionic liquids

The hydrogen bond interactions between methyl-imidazolium cation (MIM+) and fatty acid anions (CmHnCOO–, where m = 1–6; n-3–13) of ionic liquids are studied in both gas phase and water phase using density functional theory. The structural properties show that the presence of N–H···O and C–H···O hydrogen bonds between [MIM]+ and [CmHnCOO]– (m = 1–6; n-3–13) ionic liquids. From the vibrational frequency analysis, it was found that the hydrogen bond interaction between [MIM]+ and [CmHnCOO]– (m = 1–6; n-3–13) ionic liquids are red-shifted in frequency. The natural bond orbital analysis show that the N–H···O hydrogen bond associated with the large charge transfer which has the higher stabilization energy (i.e. E(2) ~ 38 kcal/mol). Further, the cation/anion–water cluster (H2O)1–3 interactions show that the water molecules are preferred to interact with anions. In the case of ionic liquid–water cluster interaction, the water molecules occupies the interstitial space between cation and anion of ionic liquids which results in weakening the cation–anion interaction.

Delineating molecular interactions within surface active ionic liquids + tartrazine dye solutions: A comparative study with conventional surfactant-DTAC

Surface active ionic liquids (SAILs) have been used in various technological fields. Moreover, the deep understanding of interactions exist in SAIL and dye systems will enhance their utility in various fields. In this study, the interactions of cationic Ionic liquids/surfactant 1-Methyl-3-octylimidazoilum chloride [C8mim][Cl], 1-Methyl-3-decylimidazolium chloride[C10mim][Cl], Dodecyl trimethylammonium chloride (DTAC) with anionic dye tartrazine were investigated by state of the art techniques i.e., conductivity, UV–visible spectroscopy, fluorescence spectroscopy and surface tension. The Critical micelle concentration (CMC) of tartrazine-added aqueous ILs/surfactant solutions were obtained, and a decrease is observed after addition of dye. Further, with the increase in alkyl chain length of ILs, the CMC is considerably reduced. Spectroscopic studies reveal a change in spectra of dye which hints ILs/surfactant dye interaction. The binding constant (Kb) is calculated by conductivity, UV-visible, fluorescence methods, which follows the order DTAC>[C10mim][Cl]>[C8mim][Cl]. Computational studies give an idea of the HOMO – LUMO energy gap between the donor and acceptor orbitals of ILs/surfactant and dye, which can be useful in the prediction of the feasibility of interaction between two entities.

A thermodynamic investigation of the effect of cationic structure on the self-aggregation behavior of Surface-Active ionic liquids in the presence of an amino acid

A series of imidazolium-based ionic liquids (ILs) with varying side alkyl chain length at N3 position which includes [C12mim][Br], [C12eim][Br], and [C12bim][Br] have been synthesized and characterized by 1H NMR. Then, their aggregation behavior in the presence of different concentrations of the amino acid L-Tryptophan (L-Trp) at different temperatures has been examined using conductometric, tensiometric, and UV–vis (absorption spectra) techniques. The critical micelle concentration (CMC) of ILs has been investigated in the absence and presence of amino acid to acquire a better understanding of the colloidal behavior of ILs in presence of amino acid as an external additive. The addition of amino acid is observed to reduce the CMC values of the ILs examined in an aqueous media. Likewise, applying a charged pseudo-phase model of micellization, the thermodynamic parameters of micellization, such as a change in standard free energy (ΔGmo), change in standard enthalpy (ΔHmo), and change in standard entropy (ΔSmo), have been scrutinized from the dependence of CMC on temperature. The surface tension approach was also used to evaluate interfacial characteristics. It was discovered that increasing the length of the side chain increases surface activity. All of the estimated parameters were utilized to determine the electrostatic and hydrophobic contributions of IL to the formation of micellar aggregates.

Influence of an antibiotic drug neomycin sulphate on mixed micellization behavior of imidazolium based surface-active ionic liquids in aqueous media

Imidazolium-based surface-active ionic liquids (SAILs) have unique physicochemical features that make them ideal for biomedical applications. Because SAILs have a higher surface activity than conventional surfactants, they can improve drug permeability across biomembranes, making them superior drug carriers than existing solutions. In-depth studies of interactions prevailing in mixed micellar system of SAILs in the presence of drug are required to fully exploit the promise of these materials in drug delivery applications. Thus, various thermodynamic, mixed micellar and surface-active properties of two imidazolium-based SAILs with different cationic structures i.e.1-dodecyl-3-ethylimidazolium bromide [C12eim][Br] and 1-dodecyl-3-butylimidazolium bromide [C12bim][Br] have been determined in water and 5 mM neomycin sulphate solution in aqueous media. The study has been conducted for different mole fractions of mixed micellar system of SAILs using conductivity and surface tension measurement techniques. Various theoretical models such as Clint, Rubingh, Motomura and Rodenas models have been applied to understand the interactions prevailing in the mixed [C12eim][Br] /[C12bim][Br] system in water and neomycin sulphate solution in aqueous media.

Experimental study on coal dust wettability strengthened by surface active ionic liquids.

The water wettability of coal dust was very important for dust control when using water-based dust suppressant materials. The coal dust wettability strengthened by surface active ionic liquid was studied in this paper. The surface activity of ten ionic liquids with different anions Cl-, Br-, [BF4]-, [NTf2]- and cations [HOEtMIm]+, [Cnmim]+ (n = 4, 12, 14, 16) was studied by surface tension test. The water wettability of raw coal dust can be improved individually by adding ionic liquid to water or pre-treating coal dust by ionic liquids. The wettability of lignite was improved little, but that of bituminous coal and anthracite were improved much. The dual strengthened effects of ionic liquids on coal dust wettability were studied by the wetting results between ionic liquids solutions and ionic liquid-treated coal samples. The wettability of lignite can be strengthened under the combined action of [HOEtMIm][NTf2] and [C12MIm]Br, while other dual effects were not satisfactory. All ionic liquids combination had strengthened effects on the wettability of bituminous coal and anthracite, especially the [C12MIm]Br treatment and [C12MIm]Br solutions together had the best dual effects. The functional groups results indicated that the hydrophilic oxygen-containing functional groups in treated coal samples increased, the hydrophobic aliphatic hydrocarbon functional groups decreased and part of ionic liquids were adsorbed on the coal surface. These changes together enhanced the wettability of coal with high coalification degrees.

Design and performance analysis of a formulation based on SDBS and ionic liquid for EOR in carbonate reservoirs

A large proportion of extant crude oil is found in carbonate reservoirs worldwide. Alkylbenzene sulfonates are inexpensive anionic surfactants but they cannot be used in these reservoirs due to their incompatibility with divalent ions and high adsorption on the rocks. This paper proposes the solution to that problem by blending this kind of surfactant with surface-active ionic liquids. Namely, a formulation containing sodium dodecylbenzenesulfonate (SDBS) and cocosalkylpentaethoximethylammonium methylsulfate ([C1EG][MeSO4]) was designed for the application. Two optimal blends, at 40/60 and 73.7/26.3 SDBS/[C1EG][MeSO4] ratios, were found in synthetic seawater via equilibria and interfacial tension (IFT) studies. Core-flooding tests were carried out to check the performance of both blends. The first blend ratio (40 wt% SDBS) was selected to define an optimal formulation (1 wt% blend in synthetic seawater at 298.15 K) due to its better injectability, higher reduction of the IFT, lower adsorption, and better oil recovery. Attained tertiary oil recovery (18% of the original oil in place), with low blend adsorption (0.37 mgblend/grock), shows the promising performance of the solution. The main mechanism associated with improved oil recovery is IFT reduction. This work offers a significant advance in the application of natural petroleum sulfonates in carbonate reservoirs.

Synthesis, aggregation behavior and drug-binding interactions of fatty acid-imidazolium-based surface-active ionic liquids

The renewable fatty acid-based surface-active ionic liquids (SAILs) containing ethyl-substituted imidazolium head groups were prepared and structurally analyzed by Fourier transform infrared spectroscopy (FTIR), 1HNMR and 13CNMR spectroscopy. The products were named as; 3-ethyl-1-(2-dodecanoyl oxy) ethylimidazolium bromide [C12Eeim]Br, 3-ethyl-1-(2-tetradecanoyl oxy) ethylimidazolium bromide [C14Eeim]Br and 3-ethyl-1-(2-hexadecanoyl oxy) ethylimidazolium bromide [C16Eeim]Br. The critical micelle concentration (cmc) values of the three SAILs have been evaluated using conductivity measurements, probe-less UV–visible spectroscopy and fluorescence spectroscopy. The obtained cmc values were compared with the earlier reported non-functionalized SAILs such as [Cnmim]Br and [Cneim]Br where n = 12, 14, 16. The values were found to be 3–9 times lower mainly due to the presence of ester chain and also ethyl substituted imidazole ring. Thermodynamic parameters were evaluated by conductivity data at three different temperatures. Further, the aggregation behavior of SAILs with anesthetic drug, lidocaine hydrochloride (LC) has been studied using fluorescence. The fluorescence and UV–visible studies showed strong synergistic interactions operating between SAILs and drug molecules involving H bonding and cation-π interactions. The interactions grew stronger with the elongation of SAIL-chain length (12–16C). Dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements suggested the formation of vesicles in SAIL-LC mixtures. These studies may thus offer an effective candidate which would serve as vectors for drug molecules in terms of their enhanced solubilization, permeability and target-specific delivery.

Purification of immunoglobulin Y from egg yolk using thermoresponsive aqueous micellar two-phase systems comprising ionic liquids

Immunoglobulin Y (IgY) represents an important class of antibodies, being present in egg yolk, with relevant medical applications and involving non-invasive methods of extraction. However, due to the complexity of egg yolk, the purification levels required for use in most medical applications demands the application of multi-step and cost-intensive techniques. Therefore, it is of upmost importance to develop a biocompatible and cost-effective downstream process to purify IgY from egg yolk. In this work, IgY was purified from the egg yolk water-soluble protein fraction (WSPF) by the application of thermoresponsive aqueous micellar two-phase systems (AMTPS) composed of the non-ionic surfactant Triton X-114 and surface-active ionic liquids (SAILs) as co-surfactants. The best thermoresponsive systems allowed, in a single step, to recover IgY in the surfactant-poor phase with a purity level of 69%, and up to 73% if consecutive extraction cycles are performed, while maintaining the structural integrity of the antibodies. Considering these results, a downstream process was designed and proposed, consisting of four main steps: (i) recovery of the WSPF; (ii) purification of IgY by applying AMTPS; (iii) isolation of the IgY from the main solvents using an ultrafiltration step; (iv) recycling of the AMTPS phase-forming components by precipitating the contaminant proteins.

Simultaneous determination of fat-soluble vitamins and carotenoids in human serum using a nanostructured ionic liquid based microextraction method

The determination of fat-soluble vitamins and carotenoids in human serum provides reliable information for diagnosing malnutrition and for establishing appropriate intervention programs. Due to the complex composition of the biological samples, the efficient sample preparation is the key to the analysis. We report here a surface active ionic liquid (SAIL)-based dispersive liquid-liquid microextraction (DLLME) method coupled with a high performance liquid chromatography (HPLC) to determine four fat-soluble vitamins and six carotenoids in human serum simultaneously. Liquid crystal structures were formed in the extract phase. And the enrichment factor of the analytes treated by DLLME was 4 to 26 times of the traditional LLE method except lycopene. The limit of determination for these compounds was determined to be between 0.002 and 0.076 µg/mL. The accuracy was validated by the standard addition method with recoveries ranging from 82.4 to 114.1%. The intra-day and inter-day relative standard deviations were 2.76–12.63% and 4.01–13.54%, respectively. The proposed DLLME coupled with the HPLC method was successfully applied in the determination of fat-soluble micronutrients in human serum.