Application Of Deep Eutectic Solvents Research Articles

Applications of deep eutectic solvents to quantitative analyses of pharmaceuticals and pesticides in various matrices: a brief review

Pharmaceuticals and pesticides are important analytes of interest in clinical, environmental, and food analyses for ensuring public health. Sample pretreatment steps are often prerequisites for the quantitative analysis of these compounds, which are generally present in low concentrations in samples with complex matrices. In compliance with the current trend towards green analytical chemistry, the replacement of conventional toxic organic solvents with ecofriendly and safe solvents has been pursued in developing sample pretreatment methods. Subsequent to several reports in 2017, deep eutectic solvents (DESs) have been increasingly applied as desirable alternative solvents in numerous types of sample pretreatment methods for the analysis of pharmaceuticals and pesticides. The present review summarizes analytical methods involving DESs as extraction solvents and as the reaction media or functional materials for preparing adsorbents to quantify pharmaceuticals and pesticides in various matrices.

Prediction of DES’ Vapor Pressure Using a New Corresponding State Model

Application of deep eutectic solvents in industrial chemical processes are improved over time in last decades. In this work, vapor pressures of 13 classes of DESs (DES 1-13) based on 5 salts and 7 hydrogen bond donors with various combinations of molar ratio were used between 343-393 K. The vapor pressure of the pure and aqueous solutions of DESs was calculated by different equations of state, which are based on “φ-φ” and γ-φ approachs. Additionally, Voutsas and Wagner models as corresponding-state models were modified to predict the vapor pressure of the pure and aqueous solutions of DESs. The total average absolute relative deviations of the Modified-Voutsas and Modified-Wagner models for the vapor pressure calculation of the pure and aqueous solutions of DESs were 7.03, 9.08 % and 5.47, 7.15 %, respectively. Moreover, the validity of vapor pressure calculation using the two modified models was checked with the aid of a linear equation for the average specific heat capacity of different DESs (23 classes of DESs) between 278.15-353.15 K. Results showed that the total average absolute relative deviations of the specific heat capacity of DESs using the Modified-Voutsas and Modified-Wagner models from the experimental data were 4.128 and 4.056 %, respectively.

A novel application of deep eutectic solvents in quantitative nuclear magnetic resonance using grey relational analysis for multi-response optimization

Developing new green solvents is one of the key subjects in Green Chemistry. Deep eutectic solvents (DES), as a new green class of tailor-made solvents, have attracted increasing attention in many areas of science because of their unique properties such as availability, low cost, biodegradability and environmental friendliness of its components. DES have been applied in many fields of chemical processing however, the full potential of these solvents is still unexplored. With an in-depth understanding of DES common properties, a novel application of DES was proposed as solvent for quantitative nuclear magnetic resonance (qNMR). In this study, an acidic DES of choline chloride and trifluoroacetic acid (TFA) at 1:3 M ratio diluted with deuterium oxide (50%) was used as qNMR solvent for simultaneous determination of Tinidazole (TZ) and Norfloxacin (NF) in pharmaceutical dosage form. This article focuses on grey relational analysis (GRA)-based Taguchi method for multi-response optimization of NMR processing parameters for the resultant of NF and TZ integral values ratios to internal standard (IS) and their coupling constant. This approach is adopted to transfer multi-response into a single response of grey relational grade (GRG). The optimal NMR processing parameters were found to be 148 number of scans, 20 s relaxation delay and 30° pulse angle. Based on the analysis of variance, number of scans was found to have the highest impact of 36.73%. Confirmation experiments conducted using the optimal parameters indicated an improvement of 56.34% in GRG. The qNMR determination of studied drugs depends on measuring the integral values ratios of the diagnostic triplet signals at 0.0025 and 0.25 ppm in 1H-NMR spectra as quantitative signals of TZ and NF, respectively to IS (Formic acid) singlet signal at 6.8 ppm. Calibration curves were created by plotting these integral ratios versus the concentration for each drug that displayed good linear relationships in the concentration ranges of 0.3–12.0 and 0.2–8.0 mg mL−1 for TZ and NF, respectively.

Application of Deep Eutectic Solvents and Ionic Liquids in the Extraction of Catechins from Tea.

This work aimed to comprehensively evaluate the potential and effectiveness of deep eutectic solvents (DESs) in the extraction of seven catechins from various tea samples. Different combinations of DES were used, consisting of Girard’s reagent T (GrT) in various mixing ratios with organic acids and choline chloride. The yields of the DES extractions were compared with those from ionic liquids and conventional solvent. DES contained malic acid, as the hydrogen bond donors showed a good solubility of catechins with different polarities. In the second part of the study, a solid-phase extraction (SPE) method was applied to the extraction of catechins from tea infusions. The method was applied to the determination of selected catechins in tea leaves and tea infusions. Furthermore, we demonstrated that the proposed procedure works well in the simultaneous monitoring of these polyphenols, which makes it a useful tool in the quality control of tea.

Application of deep eutectic solvent as a disperser in reversed-phase dispersive liquid-liquid microextraction for the extraction of Cd(II) and Zn(II) ions from oil samples

A new, sensitive, and safe pretreatment method for the analysis of Cd(II) and Zn(II) ions in oil samples prior to flame atomic absorption spectrometry was developed. For the first time, a deep eutectic solvent is used as a disperser in reversed-phase dispersive liquid-liquid microextraction procedure. For this purpose, a deep eutectic solvent with low viscosity and miscible with both aqueous and organic phases is prepared by mixing glycolic acid and mandelic acid at a molar ratio of 2:1. The variables involved in this process were studied to provide high enrichment factors. Under optimized conditions, the linear ranges of calibration curves for Cd(II) and Zn(II) ions were obtained 0.30−20 and 0.50−30 μg L−1, respectively. The obtained detection limits and enrichment factors were 0.12 and 0.18 μg L−1; and 32.7 and 32.2 for Cd(II) and Zn(II), respectively. Repeatability of the proposed method, expressed as relative standard deviation, ranged from 2.7 to 4.1 % (n = 6, C = 1 μg L−1 of each cation). Finally, the proposed method was successfully applied for the determination of Cd(II) and Zn(II) concentrations in various oil samples.

Evaluation on the properties of deep eutectic solvent-extracted lignin for potential aromatic bio-products conversion

Lignin represents a major aromatic resource in future bio-economy due to its natural abundancy. However, it is mostly produced as paper pulping by-product with heavily modified structure. The application of deep eutectic solvent (DES) has introduced an alternative lignin-first extraction method. In this work, the structural and thermal properties of DES-extracted lignin (DEEL) from oil palm empty fruit bunch using choline chloride:lactic acid (CC-LA) and choline chloride:formic acid (CC-FA) were evaluated to examine the potential of DEEL for further valorisation. CC-FA was more destructive towards the lignin’s structure, leading to a highly condensed DEEL. In contrast, CC-LA managed to preserve more β-O-4′ linkages, the usual chemical modification site. Thus, it might be more suitable for smaller chemicals production through depolymerisation process. The pyrolysis products were mainly phenolic compounds (>50 %), indicating the prospect of DEEL for phenolic-based chemicals production. The collective results demonstrate that DEEL can potentially be employed as a precursor for fuel and aromatic chemicals production.

Application of deep eutectic solvent for conjugation of magnetic nanoparticles onto graphene oxide for lead(II) and methylene blue removal

Abstract Deep eutectic solvents (DESs) have emerged as a substitute for ionic liquids with lower cost and enhanced biodegradability. The most common class of DES refers to a mixture of a quaternary ammonium or phosphonium salt and a hydrogen bond donor (e.g., carboxylic acid) with a melting point lower than that of individual components. DESs have recently shown promise for surface modification of graphene oxide (GO) nanosheets with different functional groups. We hypothesize that such surface functionalization of GO (and other carbon nanomaterials) with DESs can provide a new route to conjugate metallic nanoparticles onto GO surfaces (and similar). Here, we used a typical DES, based on choline chloride and urea, for the conjugation of pre-synthesized Fe3O4 nanoparticles onto GO nanosheets at different GO:Fe3O4 ratios. Physicochemical characterization not only confirmed the ability of DES to prepare DES/GO-Fe3O4 nanohybrids successfully, but also evidenced the influence of DES on the homogeneity and size distribution of Fe3O4 nanoparticles in these nanohybrids. DES/GO-Fe3O4 nanohybrids can perform better than both GO and Fe3O4 as adsorbents for organic dyes (methylene blue, MB) and heavy metals (Lead (II)). However, depending on the contaminant type, the contaminant removal performance varied differently for DES/GO-Fe3O4 nanohybrids with different ratios.

Deep eutectic solvent based on choline chloride and propylene glycol as a potential medium for extraction denitrification of hydrocarbon fuels

The use of deep eutectic solvents (DES) as “green” solvents could solve at least some of the environmental problems associated with the chemical and petrochemical industry. This paper investigates the applicability of DES made of choline chloride and propylene glycol in a molar ratio of 1:3 for the removal of sulfur and nitrogen compounds from hydrocarbon mixtures. Extraction experiments were performed in quasi-three-component systems, quasi-seven-component model systems and real fuel systems. All the experiments confirmed better solubility of pyridine (compared to thiophene) and nitrogen compounds (compared to sulfur ones) in the investigated DES, indicating its potential use as a denitrification agent. The basic application physico-chemical properties of the investigated DES were determined. Its applicability in multistage extraction processes was confirmed, its extraction capacity was determined and the ability of its regeneration by evaporation was demonstrated. Liquid–liquid equilibria in investigated quasi-three-component systems were described successfully by UNIQUAC activity coefficient model.

A new application of deep eutectic solvent (DES) in fish preservation

Technology in fish preservation had gone through various scope in food industry. Application of new green chemistry of deep eutectic solvent (DES) as preservative capable to help in the prevention of fish contamination by pathogenic bacteria. The aims of this study were including the synthesis of DES, the evaluation of antibacterial activity and sterility testing of the DES using fish samples. The synthesis of choline chloride-based DES was prepared by mixing with acetic acid and oxalic acid respectively. Further testing was done using disc diffusion method for the analysis of the solvent’s antibacterial activity towards E. coli, S. aureus, B. subtilis, S. Typhi and K. pneumonia. The sterility evaluation on the preservative solvent was carried out using fish samples in different temperature and time of storage. Results analysis showed potential of the DES in antibacterial activity even at low concentration of mixture. Sterility test showed promising result by maintaining pH of the solvent at 6-7. Reduction of bacteria concentration was found in the bacterial-spiked fish samples when preserved in the DES mixture. Thus, the study proved the potential of DES as a good preservative for fish compared with the controls from single component of choline chloride, acetic acid and oxalic acid respectively..

Extraction as a Critical Step in Phytochemical Analysis.

Phytochemical analysis, the chemical investigation of plants, is a rapidly developing chemical discipline with various goals such as the determination of the substance classes and the isolation and qualitative and/or quantitative analyses of bioactive compounds or their structural analysis. The analysis of plants begins with optimizing extraction procedures because they play a key role in extraction outcomes, i.e., the isolation of bioactive compounds from natural products and the selection of the subsequent tests used in the analyses. The extraction is a critical step because it is necessary to extract the desired components of the complex natural matrix without destroying them. A wide range of techniques for the extraction of bioactive compounds from natural matrixes are currently available. This review aims to describe and compare the most commonly used methods, traditional/conventional and innovative/green. It will focus on the principles behind each method and on their strengths and limitations in order to help evaluate their suitability and economic feasibility, highlighting the advantages of new innovative techniques over conventional extraction procedures. Finally, the recent application of deep eutectic solvents as a new, eco-friendly method for the extraction of bioactive compounds from natural matrixes is also discussed.

Deep eutectic solvent-based liquid-liquid microextraction for the HPLC-DAD analysis of bisphenol A in edible oils

Abstract A sample preparation method for the extraction of bisphenol A (BPA) from edible oils was established via simple, green, and sensitive deep eutectic solvent-based liquid-liquid microextraction (DES-LLME) before high-performance liquid chromatography (HPLC) with diode array detector (DAD). The deep eutectic solvent (DES) formed by tetrabutylammonium bromide (TBAB) and methanol was acted as the extractant. All parameters in the DES-LLME step, including the type and volume of extractants, the extraction time, and centrifugation time, were investigated and optimized. The application of hydrophilic DES in oils expands the selection of LLME extractants. Under the optimized conditions, the calibration curves in the range of 10–500 ng g−1 with a correlation coefficient of r > 0.999, and the detection limit was 0.8 ng g−1. The relative standard deviations of intra-day and inter-day repeatability were 4.3% and 6.2%, respectively, and the recoveries varied between 88.7% and 97.3%. This developed method was successfully employed for measuring BPA in 6 edible oil samples.

Application of deep eutectic solvents for the extraction of phenolic compounds from extra-virgin olive oil.

A HPLC-DAD/ESI-MS method has been developed and validated for the analysis of the most representative phenolic compounds in extra-virgin olive oil (EVOO) samples using a green extraction approach based on deep eutectic solvents (DESs) at room temperature. We examined ten DESs based on choline chloride and betaine in combination with different hydrogen bond donors comprising six alcohols, two organic acids, and one urea. Five phenolic compounds, belonging to the classes of secoiridoids and phenolic alcohols, were selected for the evaluation of extraction efficiency. A betaine-based DES with glycerol (molar ratio 1:2) was found to be the most effective for extracting phenolic compounds as compared to a conventional solvent. The optimization of the extraction method involved the study of the quantity of water to be added to the DES and evaluation of the sample-to-solvent ratio optimal condition. Thirty percent of water added to DES and sample to solvent ratio 1:1 (w/v) were selected as the best conditions. The chromatographic method was validated by studying LOD, LOQ, intraday and interday retention time precision, and linearity range. Recovery values obtained spiking seed oil sample aliquots with standard compounds at 5 and 100μg/g concentration were in the range between 75.2% and 98.7%.

Application of Deep Eutectic Solvents for the Extraction of Rutin and Rosmarinic Acid from Satureja montana L. and Evaluation of the Extracts Antiradical Activity.

Satureja montana L. was used in the current research as the plant exhibits numerous health-promoting benefits due to its specific chemical composition. The extraction method based on deep eutectic solvents (DESs) was used for the extraction of rutin and rosmarinic acid from this plant. Five different choline chloride-based DESs with different volumes of water (10%, 30%, and 50% (v/v)) were used for the extraction at different temperatures (30, 50, and 70 °C) to investigate the influence on rosmarinic acid and rutin content obtained by high-performance liquid chromatography with diode-array detector (HPLC-DAD) in the obtained extracts. A principal component analysis was employed to explore and visualize the influence of applied parameters on the efficiency of the extraction procedure of rutin and rosmarinic acid. Among the tested DESs, choline chloride:lactic acid (mole ratio 1:2) and choline chloride:levulinic acid (mole ratio 1:2) were the most suitable for the extraction of rutin, while for rosmarinic acid choline chloride:urea (mole ratio 1:2) was the most effective solvent. The extract showing the best antiradical activity was obtained with choline chloride:urea (mole ratio 1:1) at 30 °C and 50% H2O (v/v).

Deep eutectic solvents for biocatalytic transformations: focused lipase-catalyzed organic reactions

Biocatalysis is a green and sustainable technology for which the ideal solvent should be nontoxic, biocompatible, biodegradable, and sustainable, in addition to supporting high enzyme activity and stability. Deep eutectic solvents (DESs), a novel class of green solvents, have recently emerged as excellent alternatives for use in various biocatalytic reactions and, in particular, in lipase-catalyzed reactions with enzymes. This review discusses the achievements that have been made so far in the use of DESs as reaction media for lipase-catalyzed reactions. In addition, the application of DESs in esterification, transesterification, and amidation reactions with isolated or immobilized biocatalysts, toward enabling the synthesis of biodiesels, sugar esters, phenolipids, and fatty acyl ethanolamides, is summarized, while advances in lipase-catalyzed chemoenzymatic epoxidation reactions, C-C bond-forming Aldol reactions, and hydrolysis reactions in DESs are also discussed. This review also summarize some remaining questions concerning the use of DESs, including the intriguing role of water as a cosolvent in biocatalytic reactions carried out in DESs, and the relationship between the nature of the DESs and their influence on the enzyme stability and activity at the molecular level.

Preparation of cellulose nanofibrils from okara by high pressure homogenization method using deep eutectic solvents

The interest in the application of deep eutectic solvents (DES) as a green solvent has increased rapidly. The application of DES in agro-industrial okara treatment can be developed into industrialization. In order to simplify the degreasing, deproteinization and cellulose extraction steps in the process of pretreating okara cellulose, a new approach to cellulose extraction from okara via one-pot DES treatment is established. Three different complexing agents, choline salts in oxalic acid, in glycerol and in urea are studied in this work. The structure and properties of cellulose nanofibers (CNFs) prepared by high pressure homogenization following pretreatment of okara with anionic systhesized DES are investigated. The effects of different systems on the degree of microfibrillation of okara are analyzed using techniques such as SEM, FTIR, TD and DTG. The results indicate that by pretreating okara with choline chloride–oxalic acid type solvent, CNFs with average diameter of 27 nm are obtained using high pressure homogenization.

Application of Deep Eutectic Solvents in Food Analysis: A Review.

Deep eutectic solvents (DESs) have emerged recently as new and green solvents. DESs can be used for extraction and separation of both inorganic metallic components and organic compounds such as phenolic compounds, flavonoids, sugars, and aromatic amines from food samples. DESs possess a tunable property simply by adjusting the ratio of hydrogen bond acceptors to the hydrogen bond donors. As a green extraction medium, DESs have various applications in the pretreatment process and improve the efficiency of different food analyses. This review summarizes the findings of recent studies on the development, production, application, and efficacy of DESs in the pretreatment process of various food analyses.

Deep Eutectic Solvents as Media in Alcohol Dehydrogenase‐Catalyzed Reductions of Halogenated Ketones

AbstractThe application of deep eutectic solvents (DESs) in biotechnological processes has gained an outstanding relevance, as they can be used as greener media to obtain higher productivities and selectivities. In the present contribution, an eutectic mixture composed of choline chloride (ChCl): glycerol (1 : 2 mol/mol) has been used as a reaction medium in combination with Tris−SO4 50 mM buffer pH 7.5, applied to the alcohol dehydrogenase (ADH)‐catalyzed reduction of various carbonyl precursors of chiral halohydrins. These alcohols are key intermediates of biologically active compounds, and hence they are of industrial interest. In the presence of up to 50 % v/v of DES, these biotransformations were achieved up to 300–400 mM of the α‐halogenated ketone substrate, getting access to the final compounds with excellent conversions (usually >90 %) and enantiomeric excess (ee >99 %). Among the different ADHs tested, two stereocomplementary enzymes (Lactobacillus brevis ADH and Rhodococcus ruber ADH) afforded the best results, so both alcohol enantiomers could be obtained in all the studied examples. Selected bioreductions were scaled up to 250 mg and 1 g, demonstrating the potential that DESs can offer as media in redox processes for substrates with low solubility in water.

Metal-Free Deep Eutectic Solvents: Preparation, Physical Properties, and Significance.

In the past decade, reports detailing the preparation, characterization, and application of deep eutectic solvents (DESs) have grown in number significantly, showing signs of increased interest and attention. Indeed, these systems provide tunable polar environments attractive for their ease of synthesis and lack of need for purification. DESs are homogeneous systems composed of two or more components having a significantly depressed melting point compared to either constituent material. As interest and application of DESs grow, the need for a common understanding of their preparation and characterization is required. In this Perspective, we discuss metal-free DESs, focusing on their preparation, characterization of physical properties, and considerations for their application. We highlight inconsistencies or omissions in literature reports as well as factors for researchers to consider when investigating these systems.

Ni–La composite coating obtained using deep eutectic solvent and its electrocatalytic activity

The overpotential of hydrogen evolution reaction is one of the aspects which results in low efficacy of water electrolysers. There is a constant search for new ways to improve the catalytic activity, especially of nickel-based materials. Addition of lanthanum results in synergism and high activity towards the hydrogen evolution reaction. Due to the application of deep eutectic solvents which are characterized by a wide electrochemical window and good solvent properties for metal ions, it was possible to deposit the lanthanum–nickel alloy coating which was composed of around 40% of La. Hydrogen evolution reaction conducted on this layer resulted in a reduction of overpotential by 129 mV in comparison to pure Ni layer at current density of 1 mA cm−2. Other kinetic parameters, such as Tafel slope and exchange current density, were also significantly improved.

Direct conversion of biomass to platform chemicals, catalyzed using a deep eutectic solvent of N,N diethyl ethanol ammonium chloride-oxalic acid in a microwave reactor

Nowadays, the production of platform chemicals from cellulose is found as promising way to obtain valuable products from renewable sources instead of fossil fuel sources. In this study, conversion of cellulose into valuable products by using deep eutectic solvent as catalyst has been studied. The performance of deep eutectic solvent formed by N,N diethylethanol ammonium chloride and oxalic acid was evaluated for the conversion of cellulose in the microwave reactor. Deep eutectic solvent can be easily formed by mixing hydrogen bond acceptor and hydrogen bond donor at specified ratio. Deep eutectic solvents are found promising for processing of biomass and also to obtain ecofriendly systems due to the green nature of deep eutectic solvents (DES). This study show the applicability of DES formed by N,N diethyl ethanol ammonium chloride and oxalic acid in the conversion of cellulose at a temperature of 150, 160 and 170 °C and 2.5, 5.0 and 7.5 reaction time. The maximum C efficiency was achieved as 38.4% at 170 °C and 5 min reaction time in microwave reactor.