Separation, concentration and determination of chloramphenicol in environment and food using an ionic liquid/salt aqueous two-phase flotation system coupled with high-performance liquid chromatography

Enrichment of cinnamaldehyde from Cinnamomum cassia by electroosmotic coupled particle-assisted solvent flotation

Cinnamaldehyde has been widely applied in various fields due to its special flavor and various pharmacological activities, such as antioxidant, anti-inflammatory and antibacterial properties. The strategy of quick and efficient enrichment for cinnamaldehyde is imperative. In this study, an electroosmotic coupled particle-assisted solvent flotation (ECPASF) system was designed for the cinnamaldehyde enrichment from cinnamon. The response surface method was used to optimize extraction parameters. Under optimal operating conditions, its yield was 9.33 ± 0.11 mg/g. Such high yield of cinnamaldehyde using the ECPASF might be because electroosmosis effectively alters the permeability of plant cells, which facilitates the release of cinnamaldehyde. In addition, both the crude extract of cinnamon and pure cinnamaldehyde showed good antioxidant activity. The results demonstrated that the ECPASF system is a sustainable and effective method for the extraction of cinnamaldehyde from cinnamon. It also has the prospect of being extended to the extraction of other natural products.

Recent progress on chiral extractants for enantioselective liquid-liquid extraction

As the demand for enantiopure compounds increases, chiral separation has become increasingly important in many fields. Enantioselective liquid-liquid extraction is an up-and-coming technology for enantiomeric separation because it is highly efficient and easy to be scaled up. The key factor for enantioselective liquid-liquid extraction is the development of novel chiral extractants with high enantiorecognition performance. With successful studies on catalytically active metal complexes as chiral extractants, novel chiral extractants can be screened and designed from the field of asymmetric catalysis. Chiral ionic liquids, sulfobutylether-β-cyclodextrins bonded magnetic nanoparticles and 2,2',3,3'-tetrahydro-1,1'-spirobi[indene]-7,7'-diol (SPINOL) based phosphoric acid host show unique potential ability in enantioselective liquid-liquid extraction and they deserve further study. Brief principles, extraction equipment and solvent systems in enantioselective liquid-liquid extraction are presented in the present paper, and recent progress in development of new chiral extractants in the past decade is mainly reviewed, including metal complexes, cyclodextrins, ionic liquids, tartrate acids and crown ethers.

Simultaneous Dual-Sensing Platform Based on Aptamer-Functionalized DNA Hydrogels for Visual and Fluorescence Detection of Chloramphenicol and Aflatoxin M1

In this study, a chloramphenicol and aflatoxin M1 aptamer-functionalized DNA hydrogel was designed for the simultaneous detection of chloramphenicol and aflatoxin M1 for the first time. The acrydite-modified chloramphenicol aptamer sequence was used to synthesize the DNA hydrogel and for visual detection of chloramphenicol depending on the gel-to-sol transition of the target-responsive DNA hydrogel. The DNA hydrogel formulation was set as follows: 60% of each linear polyacrylamide-DNA conjugate and 40% of acrylamide and chloramphenicol aptamer/DNA strand-1 at a molar ratio of 1:1, and the lowest concentration of chloramphenicol leading to gel dissociation was 1.0 nM at 25 °C. Furthermore, the formalized aptamer-functionalized DNA hydrogel was used to detect aflatoxin M1 by measuring the recovery of the fluorescence signal that was quenched when the FAM-labeled aflatoxin M1 aptamer and BHQ1-labeled DNA strand-2 were hybridized to form a double-stranded DNA in the network of hydrogel. The detection platform was successfully applied to the detection of chloramphenicol and aflatoxin M1, both in aqueous solution and in milk. The aptamer-functionalized DNA hydrogel had detection (LOD) and quantification limits (LOQ) for aflatoxin M1 as 1.7 and 5.2 nM, respectively. Using two aptamer sequences with high affinity and specificity, the dual-sensing platform based on the DNA hydrogel achieved higher selectivity for chloramphenicol and aflatoxin M1, which demonstrated its potential as a reliable simultaneous detection platform against two different targets for monitoring food safety.

Magnetic nanofluid based on green deep eutectic solvent for enrichment and determination of chloramphenicol in milk and chicken samples by high-performance liquid chromatography-ultraviolet: Optimization of microextraction

In this work, magnetic nanofluid based on a deep eutectic solvent that constricts through a simple and easy route, and subsequently applied for the preconcentration and microextraction of chloramphenicol (CAP) as a hazardous drug from milk and chicken samples via syringe-to-syringe microextraction prior to its determination by high-performance liquid chromatography-ultraviolet (HPLC-UV). In addition, the optimum conditions of effective factors were searched by the central composite design (CCD), and subsequently, at their optimum value, the figures of merit were evaluated. Also, the suggested method illustrated a low limit of detection (0.2 ng mL^-1), a low limit of quantitation (0.67 ng mL^-1), and a good linear range with an R² of 0.996. The CAP relative recoveries in milk and chicken samples were 90.3%-95.1%, with relative standard deviations lower than 4.2%. The current enhancement technique is simple, easy, and rapid, which makes it suitable for quantification of CAP by HPLC-UV at trace levels in complicated materials with reliable and reproducible results.

Combination of aqueous two-phase flotation and inverse transition cycling: Strategies for separation and purification of recombinant β-glucosidase from cell lysis solution

This work was developed to solve the problems of the restriction of non-specific adsorption and time-dependent denaturation in the purification of recombinant proteins by multistage chromatographic procedures. A novel purification method (ATPF-ITC) which combining aqueous two-phase flotation (ATPF) with inverse transition cycling (ITC) was established and used to efficiently purify recombinant β-glucosidase (GLEGB) from cell lysis solution. First, GLEGB would preferentially adsorb on the nitrogen bubble interface relied on the hydrophobic property of the graphene-binding (GB) tag and enter into the top phase of ATPF. Second, GLEGB was achieved further purification by one-round ITC method based on the thermosensitive of the elastin-like polypeptide (ELP) tag. Consequently, the enzymatic activity recovery of GLEGB was 124.92% ± 0.83%, and the purification factor reached 24.26 ± 0.22. The purification results remained stable after six polymer cycles, and the process of ATPF-ITC had no negative effect on the structure of recombinant protein.

Purification of linarin and hesperidin from Mentha haplocalyx by aqueous two-phase flotation coupled with preparative HPLC and evaluation of the neuroprotective effect of linarin

The volatile oil of Mentha haplocalyx is widely used in medicine, food, and cosmetics. However, a large amount of its residue after steam extraction of volatile oil is abandoned, resulting in a waste of resources. The method of aqueous two-phase flotation coupled with preparative high-performance liquid chromatography was established for the separation and purification of nonvolatile active compounds from Mentha haplocalyx for the first time. The parameters of the two-phase aqueous flotation were optimized. Under the optimal conditions including flotation solvent PEG 1000 aqueous solution (1:1, w/w), pH 5, (NH₄ )₂ SO₄ concentration of 350 g/L in aqueous phase, N₂ flow rate of 20 mL/min, and flotation time of 20 min, the flotation efficiency of linarin, hesperidin, and didymin was 82.24, 76.38, and 89.33%, respectively. The linarin and hesperidin with the high purities of 95.8 and 97.2%, respectively, were obtained by using preparative high performance liquid chromatography. The neuroprotective effect of linarin against H₂ O₂ -induced oxidative stress in rat hippocampal neurons was investigated. The experimental result indicated that linarin could alleviate H₂ O₂ -induced oxidative stress. The work indicated that the combination of aqueous two-phase flotation and preparative high performance liquid chromatography is a feasible and practical method for the purification of nonvolatile active substances from Mentha haplocalyx, which would provide a reference process for the comprehensive utilization of M. haplocalyx. Especially, linarin might be used as a good source of natural neuroprotectants.

The Influence of Ionic Liquids on the Effectiveness of Analytical Methods Used in the Monitoring of Human and Veterinary Pharmaceuticals in Biological and Environmental Samples-Trends and Perspectives

Recent years have seen the increased utilization of ionic liquids (ILs) in the development and optimization of analytical methods. Their unique and eco-friendly properties and the ability to modify their structure allows them to be useful both at the sample preparation stage and at the separation stage of the analytes. The use of ILs for the analysis of pharmaceuticals seems particularly interesting because of their systematic delivery to the environment. Nowadays, they are commonly detected in many countries at very low concentration levels. However, due to their specific physiological activity, pharmaceuticals are responsible for bioaccumulation and toxic effects in aquatic and terrestrial ecosystems as well as possibly upsetting the body's equilibrium, leading to the dangerous phenomenon of drug resistance. This review will provide a comprehensive summary of the use of ILs in various sample preparation procedures and separation methods for the determination of pharmaceuticals in environmental and biological matrices based on liquid-based chromatography (LC, SFC, TLC), gas chromatography (GC) and electromigration techniques (e.g., capillary electrophoresis (CE)). Moreover, the advantages and disadvantages of ILs, which can appear during extraction and separation, will be presented and attention will be given to the criteria to be followed during the selection of ILs for specific applications.

Sono- and photoelectrocatalytic processes for the removal of ionic liquids based on the 1-butyl-3-methylimidazolium cation

In this work, sono- and photoelectrolysis of synthetic wastewaters polluted with the ionic liquids 1-Butyl-3-methylimidazolium acetate (BmimAc) and chloride (BmimCl) were investigated with diamond anodes. The results were compared to those attained by enhancing bare electrolysis with irradiation by UV light or with the application of high-frequency ultrasound (US). Despite its complex heterocyclic structure, the Bmim⁺ cation was successfully depleted with the three technologies that were tested and was mainly transformed into four different organic intermediates, an inorganic nitrogen species and carbon dioxide. Regardless of the technology that was evaluated, removal of the heterocyclic ring is much less efficient (and much slower) than oxidation of the counter ion. In turn, the counter ion influences the rate of removal of the ionic liquid cation. Thus, the electrolysis and photoelectrolysis of BmimAc are much less efficient than sonoelectrolysis, but their differences become much less important in the case of BmimCl. In this later case, the most efficient technology is photoelectrolysis. This result is directly related to the generation of free radicals in the solution by irradiation of the electrochemical system with UV light, which contributes significantly to the removal of Bmim⁺.

On-line solvent exchange system: Automation from extraction to analysis

Removal of organic solvent from sample extracts is required before analysis by reversed phase HPLC to preserve chromatographic performance and allow for bigger injection volumes, boosting sensitivity. Herein, an automated on-line extraction evaporation procedure is integrated with HPLC analysis. The evaporation occurs inside a 200 μm microfluidic channel confined by a vapor permeable membrane. A feedback control algorithm regulates evaporation rate keeping the output flow rate constant. The evaporation process across this membrane was firstly characterized with water/solvent mixtures showing organic solvent removal capabilities. This system allowed continuous methanol, ethanol and acetonitrile removal from samples containing up to 80% organic solvent. An evaporative injection procedure was developed demonstrating the use of the device for fully integrated extract reconstitution coupled to HPLC analysis, applied to analysis of the antibiotic chloramphenicol in milk samples. Sample reconstitution and collection was performed in less than 10 min and can be executed simultaneously to HPLC analysis of the previous sample in a routine workflow, thus having minimal impact on the total sample analysis time when run in a sequence.

The role of ionic liquid [C4 C1 im]Br as an adjuvant on the two-phase formation and the extraction of l-phenylalanine in ABS composed of PEG400 and potassium citrate at different temperatures

The potential of {polyethylene glycol 400 + potassium citrate} aqueous biphasic system (ABS) with ionic liquid (IL) 1-butyl-3-methylimidazolium bromide ([C₄ C₁ im]Br) as an adjuvant is examined for the extraction of l-phenylalanine (Phe), as a model biomolecule, at different temperatures and system compositions. The binodal curves and liquid-liquid equilibrium data were determined by the addition of 5 wt% IL to investigate its effect on phase diagrams and Phe partition coefficients. The results indicate that binodal curves of systems with and without IL are more deviated from each other with decreasing temperature. Moreover, IL has a high tendency to partition into the PEG-rich phase. This tendency increases with increasing temperature and system compositions. For Phe, the partition coefficients obtained in this work (K_Phe ≈ 5.5-81.2) are significantly higher than those observed in other conventional PEG-inorganic salt ABS (K_Phe ≈ 0.5-2.5), water-immiscible ILs two-phase extraction systems (K_Phe ≈ 0.02-1.2), or even, in the IL-based ABS with the same IL as the main phase-forming component (K_Phe ≈ 3.2). The phase hydrophobicity, salting-out and π⋯π stacking seem to be the main driving forces to affect the extraction aptitude of the studied ABS for Phe. Furthermore, the performance of using [C₄ C₁ im]Br as adjuvant to improve the partition of Phe in the studied ABS at different temperatures seems to be ruled by the differences in the phases hydrophobicities. Finally, the experimental tie lines and partition coefficients are accurately correlated using the NRTL model. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018 © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1149-1166, 2018.

Simultaneous extraction and concentration of water pollution tracers using ionic-liquid-based systems

Human activities are responsible for the release of innumerous substances into the aquatic environment. Some of these substances can be used as pollution tracers to identify contamination sources and to prioritize monitoring and remediation actions. Thus, their identification and quantification are of high priority. However, due to their presence in complex matrices and at significantly low concentrations, a pre-treatment/concentration step is always required. As an alternative to the currently used pre-treatment methods, mainly based on solid-phase extractions, aqueous biphasic systems (ABS) composed of ionic liquids (ILs) and K₃C₆H₅O₇ are here proposed for the simultaneous extraction and concentration of mixtures of two important pollution tracers, caffeine (CAF) and carbamazepine (CBZ). An initial screening of the IL chemical structure was carried out, with extraction efficiencies of both tracers to the IL-rich phase ranging between 95 and 100%, obtained in a single-step. These systems were then optimized in order to simultaneously concentrate CAF and CBZ from water samples followed by HPLC-UV analysis, for which no interferences of the ABS phase-forming components and other interferents present in a wastewater effluent sample have been found. Based on the saturation solubility data of both pollution tracers in the IL-rich phase, the maximum estimated concentration factors of CAF and CBZ are 28595- and 8259-fold. IL-based ABS can be thus envisioned as effective pre-treatment techniques of environmentally-related aqueous samples for a more accurate monitoring of mixtures of pollution tracers.

Ionic-Liquid-Mediated Extraction and Separation Processes for Bioactive Compounds: Past, Present, and Future Trends

Ionic liquids (ILs) have been proposed as promising media for the extraction and separation of bioactive compounds from the most diverse origins. This critical review offers a compilation on the main results achieved by the use of ionic-liquid-based processes in the extraction and separation/purification of a large range of bioactive compounds (including small organic extractable compounds from biomass, lipids, and other hydrophobic compounds, proteins, amino acids, nucleic acids, and pharmaceuticals). ILs have been studied as solvents, cosolvents, cosurfactants, electrolytes, and adjuvants, as well as used in the creation of IL-supported materials for separation purposes. The IL-based processes hitherto reported, such as IL-based solid-liquid extractions, IL-based liquid-liquid extractions, IL-modified materials, and IL-based crystallization approaches, are here reviewed and compared in terms of extraction and separation performance. The key accomplishments and future challenges to the field are discussed, with particular emphasis on the major lacunas found within the IL community dedicated to separation processes and by suggesting some steps to overcome the current limitations.

Response Surface Methodology Modelling of an Aqueous Two-Phase System for Purification of Protease from Penicillium candidum (PCA 1/TT031) under Solid State Fermentation and Its Biochemical Characterization

Penicillium candidum (PCA 1/TT031) synthesizes different types of extracellular proteases. The objective of this study is to optimize polyethylene glycol (PEG)/citrate based on an aqueous two-phase system (ATPS) and Response Surface Methodology (RSM) to purify protease from Penicillium candidum (PCA 1/TT031). The effects of different PEG molecular weights (1500-10,000 g/mol), PEG concentration (9%-20%), concentrations of NaCl (0%-10%) and the citrate buffer (8%-16%) on protease were also studied. The best protease purification could be achieved under the conditions of 9.0% (w/w) PEG 8000, 5.2% NaCl, and 15.9% sodium citrate concentration, which resulted in a one-sided protease partitioning for the bottom phase with a partition coefficient of 0.2, a 6.8-fold protease purification factor, and a yield of 93%. The response surface models displayed a significant (p ≤ 0.05) response which was fit for the variables that were studied as well as a high coefficient of determination (R²). Similarly, the predicted and observed values displayed no significant (p > 0.05) differences. In addition, our enzyme characterization study revealed that Penicillium candidum (PCA 1/TT031) produced a slight neutral protease with a molecular weight between 100 and 140 kDa. The optimal activity of the purified enzyme occurred at a pH of 6.0 and at a temperature of 50 °C. The stability between different pH and temperature ranges along with the effect of chemical metal ions and inhibitors were also studied. Our results reveal that the purified enzyme could be used in the dairy industry such as in accelerated cheese ripening.

Aqueous two-phase system (ATPS): an overview and advances in its applications

Aqueous two-phase system (ATPS) is a liquid-liquid fractionation technique and has gained an interest because of great potential for the extraction, separation, purification and enrichment of proteins, membranes, viruses, enzymes, nucleic acids and other biomolecules both in industry and academia. Although, the partition behavior involved in the method is complex and difficult to predict. Current research shows that it has also been successfully used in the detection of veterinary drug residues in food, separation of precious metals, sewage treatment and a variety of other purposes. The ATPS is able to give high recovery yield and is easily to scale up. It is also very economic and environment friendly method. The aim of this review is to overview the basics of ATPS, optimization and its applications.

Synthesis of a phenylboronic acid-functionalized thermosensitive block copolymer and its application in separation and purification of vicinal-diol-containing compounds

Phenylboronic acid-functionalized PEO₂₀PPO₆₀PEO₂₀ was synthesized and used to separate ortho-hydroxyl compounds as the collector in an aqueous two-phase flotation system.

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 novel colorimetric sandwich aptasensor based on an indirect competitive enzyme-free method for ultrasensitive detection of chloramphenicol

Analytical methods for detection and quantitation of chloramphenicol in blood serum and foodstuffs arse highly in demand. In this study, a colorimetric sandwich aptamer-based sensor (aptasensor) was fabricated for sensitive and selective detection of chloramphenicol, based on an indirect competitive enzyme-free assay using gold nanoparticles (AuNPs), biotin and streptavidin. The designed aptasensor acquires characteristics of AuNPs, including large surface area and unique optical properties, and strong interaction of biotin with streptavidin. In the absence of chloramphenicol, the sandwich structure of aptasensor forms, leading to the observation of sharp red color. In the presence of target, functionalized AuNPs could not bind to 96-well plates, resulting in a faint red color. The fabricated colorimetric aptasensor exhibited high selectivity toward chloramphenicol with a limit of detection as low as 451 pM. Moreover, the developed colorimetric aptasensor was successfully used to detect chloramphenicol in milk and serum with LODs of 697 and 601 pM, respectively.

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 Cu(2+) 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.