Hydrophilic Deep Eutectic Solvents Research Articles

A simple HPLC-DAD method for analysis of phenolic acids: Addition effect of a hydrophilic deep eutectic solvent to the mobile phase

AbstractThe analysis of phenolic acids (PAs) is of great importance, because they are frequently present in natural products and their derivatives, and these compounds also have multiple beneficial effects to human health. This work is focusing on the separation of seven PAs (caffeic acid, coumaric acid, gallic acid, ferulic acid, protocatechuic acid, sinapic acid, and syringic acid), in a reversed-phase liquid chromatographic (RP-HPLC) isocratic method using a hydrophilic deep eutectic solvent (DES) as a mobile phase additive. The analysis was carried out with a diode array detector. The used DES was composed by choline chloride and glycerol, and it was characterized by infrared spectroscopy. The combination of choline chloride:glycerol (1:4) added at 0.25% to mobile phase composed of 0.15% formic acid aqueous solution and methanol (80:20), showed the best separation for target analytes. The new proposed method was validated, and results indicated that the proposed method is linear, selective for almost all analytes, provided high sensitivity with limit of detection ranges from 0.009 to 0.023 mg mL−1, and has satisfactory precision and accuracy, with values of relative standard deviation of 0.24–2.65% and recoveries of 97.97–109%, respectively. Additionally, this method was successfully applied to simultaneous determination of phenolic acids in three kinds of samples of powder to prepare lemon flavour drink enriched with black tea extract.

New Class of Tunable Choline Bromide-Based Hydrophobic Deep Eutectic Solvents for the Extraction of Bioactive Compounds of Varying Polarity from a Plant Matrix.

Deep eutectic solvents (DESs) are a class of sustainable solvents that have found numerous applications in different fields. One of their main attributes is the possibility of easily modifying their physicochemical properties by varying the type of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) that comprise them. Choline chloride ([Ch+][Cl-])-based hydrophilic DESs were among the first studied and the most used because of their capacity to easily create a hydrogen bonding network that lies in its unique chemical structure, characterized by a hydroxyl substituent within the ammonium headgroup. In this study, a new class of hydrophobic [Ch+][Br-]-modified salts were synthesized to produce HBAs with similar properties to choline for the preparation of hydrophobic DESs. Six different [Ch+][Br-]-based HDESs were prepared and characterized in terms of hydrophobicity, viscosity, and solvation properties (hydrogen bonding, dispersion, dipolarity/polarizability, n-π, and π-π interactions). They were employed as solvents in a microextraction method for the determination of phytochemicals in Cannabis sativa L. plant. The extraction performance of the [Ch+][Br-]-based HDESs was compared to eutectic mixtures based on conventional hydrophobic HBAs, and the results revealed that the unique properties of [Ch+][Br-]-modified salts allowed for the extraction of both hydrophilic (i.e., flavonoids) and hydrophobic compounds (i.e., cannabinoids).

Green solvents for the selective extraction of bioactive compounds from by-products of the coffee production chain

Approximately 15–20 million tonnes of by-products were generated globally in the coffee production chain during the 2020/21 season. The current uses for these by-products are inadequate or contribute to environmental degradation. This work reports the screening of hydrophilic and hydrophobic solvents, including deep eutectic solvents (DES), for their ability to extract the valuable metabolites caffeine and chlorogenic acid (markers in commercial extraction) from four coffee-related by-products. Water was the best solvent for recovering caffeine and chlorogenic acid from defective green coffee beans, while all hydrophilic DES surpassed water in the extraction of chlorogenic acid from coffee pulp. For the two remaining by-products, at least one DES was as good or better at extracting the caffeine or chlorogenic acid compared to water. The array of hydrophobic solvents tested here showed different selectivities, allowing the annotation of 12 compounds that have not been previously reported in coffee by-products. These results demonstrate the ability to obtain a new and controllable range of extracts from coffee by-products using green and functional solvents.

Using novel hydrophobic deep eutectic solvents to improve a sustainable carotenoid extraction from orange peels

Carotenoids are a group of pigments that play a significant role in human health due to their antioxidant properties. This emphasises the importance of their extraction using sustainable solvents as alternatives to hazardous solvents. This study aimed to select and optimise the most promising deep eutectic solvent (DES) for a sustainable carotenoid extraction from orange peels by considering parameters such as efficiency, stability, and physicochemical properties. COSMOtherm software was used to screen 68 hydrophobic and hydrophilic DES. The experimental results demonstrated efficient extraction yields when using hydrophobic DES such as Menthol: Camphor (163.5 ± 1.1 mg/100gfw), and the stability of carotenoids in this solvent was 56% for total carotenoids after 60 days at 4 °C. The ultrasound extraction technique was selected for the optimisation process, and the optimal conditions were 60% ultrasound intensity (120 W), a solvent-to-solid ratio of 20 mL, and an extraction time of 20 min with a yield of 653.5 mg/100 gfw. The results presented in this study demonstrate the capacity of novel hydrophobic DES to extract carotenoids and identify this solvent as a good and sustainable alternative to organic solvents. Improved carotenoid extraction combined with non-toxicity, edibility, and enhanced carotenoid stability makes these extracts appealing for use in food product fortification.

Switchable deep eutectic solvents for sustainable extraction of β-carotene from millet

Switchable deep eutectic solvents (DESs) were combined with phenolic antioxidants to extract β-carotene from millet, and the recovery and reuse capacities of DESs were evaluated. The pre-treatment of millet using ultrafine grinding is beneficial to the extraction of β-carotene. The hydrophobic DESs synthesized from N,N-dimethylcyclohexylamine and n-butanol were used as the extractants for grinding-assisted extraction of β-carotene from millet, and phenolic antioxidants were used to improve the stability of β-carotene. The hydrophobic DESs were switched to hydrophilic DESs by adjusting pH to recover the hydrophobic β-carotene solid. The remaining hydrophilic DESs could be switched to hydrophobic DESs by adjusting pH to extract new millet samples. In five DES recovery and reuse processes, the yield did not decrease, and more than 91.0% of β-carotene from millet could be directly recovered in solid state each time. In summary, a rapid, efficient, and sustainable method for β-carotene extraction was developed.

Green approach to extract bioactive compounds from orange peel employing hydrophilic and hydrophobic deep eutectic solvents

Consumer interest in natural products with advantageous biological impacts on their health has increased in recent years. Therefore, academic and industrial communities have concentrated their research on developing sustainable techniques for extracting bioactive compounds from natural resources. In the present study, extracts rich in bioactive compounds from orange peel were obtained using novel hydrophilic and hydrophobic deep eutectic solvents (DESs). Bioactive compounds such as carotenoids and polyphenols, their stability, antioxidant capacity, permeability, and biological activity were determined to consider their inclusion in food formulations. The results demonstrated that the highest total carotenoid values were obtained with hydrophobic DESs using DL-Menthol: camphor (163.5 ± 1.1 mg/100gfw), DL-Menthol: Eucalyptol (168.7 ± 1.7mg/100gfw), and lauric acid: octanoic acid (153.1 ± 7.1 mg/100gfw). Total polyphenols were higher in hydrophilic DESs such as proline: malic acid (282.8 ± 7.3 mg/100gfw). The antioxidant values showed that hydrophobic extracts have higher antioxidant activity than traditional solvents. Carotenoid stability was also improved using DL-Menthol: camphor, while lactic acid: glucose and proline: malic acid showed a better capacity to stabilize polyphenols. To simulate carotenoid and polyphenol permeation, the Parallel Artificial Membrane Permeability Assay (PAMPA) was used and demonstrated that DESs can enhance the permeability of these bioactive compounds. Biological tests were also performed, and the antiproliferative effect in HeLa cells showed only 26.70% cell viability in DL-Menthol: camphor extracts. Based on the presented results, DESs can be used to extract hydrophilic and hydrophobic compounds from orange peels, and the obtained extracts could be included in food formulations, avoiding the solvent elimination process.

Diffusivities and solubilities of carbon dioxide in deep eutectic solvents

Deep eutectic solvents (DESs) have been identified as promising solvents for CO2 capture because of their low volatility and tunable properties. Detailed information on solute solubility and diffusivity is crucial for the design and operation of processes involving mixtures composed of DESs and dissolved gases. The infinite-dilution diffusion coefficients of CO2 in 33 DESs (both hydrophilic and hydrophobic) were gravimetrically determined with a magnetic suspension balance at 298.15 and 313.15 K along with the Henry’s constants of CO2 in these DESs. Interestingly, the diffusion coefficients of CO2 at infinite dilution in hydrophobic DESs were found to be much higher than those in hydrophilic DESs. In order to better understand this phenomenon, CO2 diffusion coefficients under infinite dilution conditions in traditional solvents and ionic liquids (ILs) were summarized from literature, which revealed that the CO2 diffusivity is often approximately inversely proportional to the square root of the viscosity. However, the hydrophilic DESs and some ILs/hydrophobic DESs with large molar volumes displayed a significantly different behavior. The OH group seems to hinder CO2 diffusion, while the presence of multiple long flexible alkyl chains in the DES constituents can facilitate the diffusion. Modified Wilke–Chang correlations were successfully developed to describe the infinite-dilution diffusion coefficients in the measured DESs. Tetraoctylammonium bromide - decanoic acid (1:2) was found promising for further investigation for application in CO2 capture processes with supported liquid membranes or physical absorption.

Evaluation of blood lead levels in opium addicts and healthy control group using novel deep eutectic solvent based dispersive liquid-liquid microextraction followed by GFAAS.

Today, drug dealers and sellers add lead compounds to these substances to get more profit. As a result, drug users are heavily exposed to lead, and lead poisoning is clearly seen in most of them. Therefore, it is especially important to check the blood lead levels in these people. In this research, an efficient and eco-friendly pretreatment method was established by deep eutectic solvent for dispersive liquid-liquid microextraction (DES - DLLME) followed by graphite furnace atomic absorption spectrometry (GFAAS) analysis. The selected hydrophilic deep eutectic solvent consists of l-menthol and (1S)-( +)-camphor-10-sulfonic acid (CSA) at a 5:1 molar ratio as a green solvent instead of traditional toxic organic solvents. Under the optimal extraction conditions, the introduced method exhibited good linearity with coefficient of determination (r2) 0.9975 and an acceptable linear range of 0.3-80µg L-1. Accordingly, the detection limit was 0.1µg L-1 (S/N = 3) for lead ions, and the high enrichment factor (240) was obtained. The proposed method was successfully applied to analysis lead ions in real blood samples, which is a promising technique for biological samples. The case samples were classified and analyzed based on age, duration of consumption, and type of substance. The results showed that there was no significant difference between blood lead levels in different age groups and different duration of use, while blood lead levels were higher in opium residue (shireh) users than in opium users.

Hydrophobic deep eutectic solvent‐based ionic conductive gels with highly stretchable, fatigue‐resistant and adhesive performances for reliable flexible strain sensors

AbstractOwing to the advantages of temperature resistance, low cost, and biocompatibility, deep eutectic solvent (DES)‐based ionic conductive gels have attracted increasing research interest for flexible devices in recent years. However, current DES gels are all based on hydrophilic DES, which tend to absorb a large amount of environmental moisture, resulting in gel softening and adversely affecting the durability of the device. In this work, we highlight for the first time that N,N‐dimethylacrylamide monomer, and the obtained polymer can form hydrogen‐bonding networks with hydrophobic DES, methyl trioctyl ammonium chloride/ethyl 4‐hydroxybenzoate (1:2), thereby obtaining a hydrophobic DES‐based gel through photo‐polymerization. The resultant DES gel displays high stretchability (~900%), toughness (341.14 kJ m−3), anti‐fatigue property (recovery after 500 compression cycles), desirable conductivity (0.12 mS cm−1), adhesiveness and high transparency (>90% visible light transmittance). Notably, the hydrophobic DES‐based gel absorbs only 2 wt% water but exhibits significant water‐induced stiffening after exposing in ambient air for 1 week. These properties lead to the successful realization of the DES gels as wearable sensors to precisely monitor human motion. This work may open new avenues for the development of hydrophobic DES‐based gel ionotronics with functional performance.

Ultrasonic-assisted dispersive liquid–liquid microextraction based on hydrophilic deep eutectic solvents: Application to lead and cadmium monitoring in water and food samples

A green and innovative ultrasonic-assisted dispersive liquid–liquid microextraction using hydrophilic deep eutectic solvents (UA-HDES-DLLME) was developed for the selective and simultaneous extraction and enrichment of Pb (II) and Cd (II) in water and food samples for flame atomic absorption spectrometry. Several natural deep eutectic solvents (NADES) were used for the preparation of six different HDES and methyl violet was used as chelating reagent. Effective parameters such as pH, sonication time, methyl violet amount, DES type, dispersive solvent types, etc were optimized. Relative standard deviation (RSD) and preconcentration factor (PF) were 4.0% and 80. Low limits of detection (LOD, 1.3 ng mL−1 for Pb (II) and 0.33 ng mL−1 for Cd (II)) and quantification (LOQ, 4.0 ng mL−1 for Pb (II) and 1.0 ng mL−1 for Cd (II)) were found. The method accuracy was confirmed with analyses of certified reference materials.

Sustainable extraction of polyphenols from millet using switchable deep eutectic solvents

In this study, polyphenols were extracted from millet with a high hydrostatic pressure (HHP) pretreatment combined with switchable deep eutectic solvent (DES) extraction. The antioxidant activity of the extract was evaluated, and the switchable DESs were recycled and reused. HHP pretreatment destroyed the cell structure of millet to facilitate the extraction of polyphenols. The grinding-assisted extraction was used as the extraction method by taking switchable DES (octanoic acid-linalool) as the extraction solvent and β-cyclodextrin as the auxiliary extraction reagent. The hydrophilic DES was switched to the hydrophobic DES to recover millet polyphenols. The hydrophobic DES was recycled and switched to the hydrophilic DES for extracting new millet samples. After being reused five times, the yield of millet polyphenols using recycled DESs did not decrease significantly. In conclusion, HHP pretreatment combined with switchable DES extraction is considered as a green, efficient, and sustainable method for bioactive compounds.

A Critical Review of Emerging Hydrophobic Deep Eutectic Solvents' Applications in Food Chemistry: Trends and Opportunities.

Due to their low cost, biodegradability, and ease of preparation, deep eutectic solvents (DESs) are considered promising green alternatives to conventional solvents, as exploiting green solvents has been a research focus for achieving sustainable development goals. Most DESs in published studies are hydrophilic. On the other hand, the DES's hydrophilicity restricts its practical applicability to just polar molecules, which is a vital disadvantage to this extractant. Hydrophobic DES (HDES) has been developed as a new extractant adept at extracting nonpolar inorganic and organic compounds from aqueous systems. Although there has been little research on HDESs (HDES publications account for <10% of DES), specific intriguing applications have been discovered, requiring investigation and comparisons. As a result, this review covers the applications of emerging HDES in detecting pesticide residues, food additives, contaminants in food packaging, heavy metals, separation and extraction processes in food. According to the available literature, HDESs have the potential to overcome the limitations of hydrophilic DESs and be used in a broader range of applications in food with greater efficiency, which has received little attention. HDES is expected to substitute a lot of harmful organic extractants used for analytical reasons (food chemistry) in the future. Besides, the limitations of HDES were reviewed, and future studies were provided. This will serve as a reference for green chemistry advocates and practitioners in food science who want to minimize pollution and improve efficiency and benefit from the further development of HDESs.

Utilization of hydrophilic and hydrophobic deep eutectic solvents for dispersive liquid-liquid microextraction of bicalutamide from water and spiked human plasma

Herein, a green dispersive liquid-liquid microextraction (DLLME) based on hydrophilic and hydrophobic deep eutectic solvents (DESs) was developed for the enrichment of bicalutamide (BIC) from water and spiked human plasma. Six hydrophobic and three hydrophilic DESs were synthesized and evaluated. The hydrophilic DES, composed of tetrabutylammonium bromide and acetic acid in a molar ratio of 1:2, was used as a dispersive solvent. Moreover, the hydrophobic DES, composed of borneol and capric acid in a molar ratio of 1:2, was applied as an extracting solvent. Significant factors affecting the extraction efficiency were investigated through the one-factor-at-a-time (OFAT) strategy. The optimized method was validated in terms of linearity, limits of detection and quantitation, accuracy, precision, and matrix effect. Good linearity with an excellent correlation coefficient (r2 > 0.9999 and 0.9987) was achieved as well as low limits of detection of 0.022 and 0.048 μg/mL and preconcentration up to 53.2 and 92.1 folds for water and plasma, respectively. The proposed DLLME method was coupled with spectrophotometric detection and applied for the analysis of BIC in river water and spiked human plasma with satisfactory recoveries (92.54–99.39%). Finally, the greenness of the developed procedure was evaluated using Complex Green Analytical Procedure Index (ComplexGAPI) and Analytical GREEnness (AGREEprep) tools, exhibiting excellent greenness in comparison to the previously reported methods.

Process optimization and mechanism of oil-based drilling cuttings treatment based on hydrophilic deep eutectic solvent

Oil-based drilling cuttings (OBDC) are hazardous waste, oil removal treatment must be done before they are re-utilized. Winsor I microemulsion (composed by microemulsion phase and remaining phase) cleaning is one of oil removal methods. However, there are many surfactants in the Winsor I microemulsion, which result in high cleaning cost and high possibility of surfactant contamination. In this paper, hydrophilic deep eutectic solvent (DES) and mineral oil were used to replace the microemulsion phase and remaining phase in Winsor I microemulsion, respectively, and a low-cost and surfactant-free cleaning agent was formed. The recommended DES was the mixture of choline chloride, methanol, and water with a molar ratio of 1:2.5:3, and the best cleaning agent was the mixture of DES and mineral oil with a mass ratio of 3:1. The recommended cleaning process was that added the OBDC into cleaning agent with a mass ratio of solid to liquid of 1:3, and stirred at room temperature for 100 min. At this condition, the oil content of OBDC reduced from 14.57 wt% to 1.34 wt%. In addition, the cleaning mechanism was discussed. The DES has low surface tension and good wetting property, which is similar with the microemulsion.

Extraction of bioactive compounds from Dipsacus fullonum leaves using deep eutectic solvents

In this study, deep eutectic solvent (DES) based systems were evaluated for selective extraction and optimized for increased recovery of chlorogenic acid derivatives, flavone glycosides and iridoid glycosides from Dipsacus fullonum L. leaves. Bioactives from Dipsacus plants has shown great antioxidant and antimicrobial activities as well as effectiveness against several cancer strains and a source for anti-Borrelia compounds.Twelve different hydrophilic and hydrophobic DESs were tested to find the best solvent composition. Choline chloride and betaine were used as hydrogen bond acceptors (HBA) for the preparation of hydrophilic DESs and menthol for hydrophobic DESs. The tested hydrogen bond donors (HBD) were various organic acids and glycerol. The composition of most effective DES was optimized using the Box-Behnken design for each of the three main group of analytes from D. fullonum L. to evaluate possible selectivity and highest recovery. HPLC-DAD-MS was used to identify and quantify the main bioactive compounds extracted from plant material.The optimal extraction for highest overall recovery was achieved using a molar ratio of choline chloride and lactic acid of 1:2.4 with 35% water and 27 mL of the solvent per one gram of dry material. The optimized DES extract gave concentrations 1.8 to 2.2 times higher than traditional organic solvent extracts depending on the group of analytes.

Fast and energy-effective deep eutectic solvent-based microextraction approach for the ICP-OES determination of catalysts in biodiesel

In this research a reversed-phase deep eutectic solvent-based air-assisted dispersive liquid-liquid microextraction approach was presented for the first time and applied to the determination of catalysts (sodium, potassium, calcium and magnesium) in biodiesel samples by the inductively coupled plasma-optical emission spectroscopy. Catalysts in samples were extracted with the hydrophilic deep eutectic solvent with the assistance of air. The obtained extract phase after phase separation was analyzed by the spectral method. In this procedure the natural three-component deep eutectic solvent based on choline chloride, lactic acid and water provided fast (15 instant extraction cycles) and effective mass-transfer (extraction recovery 95-98 %). Lactic acid as precursor of the deep eutectic solvent in the presence of water provided an effective condition for separation of doubly charged metal ions. Choline chloride acted as water-soluble hydrogen bond acceptor for the deep eutectic solvent formation. The developed procedure was utilized for analysis of different nature biodiesel samples and certified reference material. It was evaluated, that the procedure is sensitive (limits of detection 3 µg kg−1), well reproducible (RSD < 7%), green (no hazardous organic solvents and mineral acids) and energy-effective (no microwave digestion of samples).

Application of Fe3O4@CNFs combined with deep eutectic solvent-based dual microextraction: a novel and green strategy for rapid determination of pesticides in edible oil samples.

A novel, green, and effective strategy employing Fe3O4-modified carbon nanofibers (CNFs) combined with deep eutectic solvent (DES) is proposedas an extraction agent to extract five pesticides in edible oil samples via dual microextraction modes, followed by high-performance liquid chromatography for determination. The Fe3O4@CNFs nanomaterial and a sequence of hydrophilic DES were prepared at first and then characterized by multiple techniques. Subsequently, the extraction performance of DES and Fe3O4@CNFs-DES was compared and Fe3O4@CNFs-DES exhibited better extraction ability. After that, several influencing parameters such as the composition of DES, the amount of Fe3O4@CNFs-DES, the dispersion methods, and the extraction time were investigated and optimized. Eventually, Fe3O4@CNFs as the solid adsorbent combined with tetrabutylammonium chloride-lactic acid-based DES as the extraction solvent were selected to extract target pesticides from oil samples. The established method received good linearity in the range 25-1000ng·g-1. The limits of detection for all analytes were in the range 2.25-7.50ng·mL-1. Satisfactory recoveries of target pesticides were obtained (ranging from 82 to 117%) with a relative standard deviation of 0.26-9.46%. The proposed method has been successfully applied to the rapid detection of target pesticides in oil samples, demonstrating its great potential for quick screening and analysis.

Deep eutectic solvents based biorefining of Value-added chemicals from the diatom Thalassiosira andamanica at room temperature

The extraction and biorefining of value-added chemicals from bioresources using green solvents are among the key agenda of the circular bioeconomy. Herein we have developed a deep eutectic solvent (DESs) based biorefining approach for clean separation and purification of value-added Fucoxanthin, Chlorophyll, and Biosilica from a diatom microalgae, Thalassiosira andamanica. Several hydrophilic/hydrophobic (DESs) based on quaternary ammonium salt as hydrogen bond acceptor and organic acids and alcohols as hydrogen bond donors were synthesized and tested for microalgae biomass dissolution and biorefining via the phase partitioning method. In an optimized process, ∼30 wt% of fresh weight diatom could be dissolved in hydrophilic DESs at room temperature, followed by a record extraction of 19.93 mg/g of Fucoxanthin via phase partitioning, with a 53 % increase in yield and an 81 % increase in selectivity over conventional solvents. 1H NMR, FTIR, LCMS, UV, and HPLC techniques were used to characterize the extracted Fucoxanthin. Subsequently, a hydrophobic DES was added to the remaining hydrophilic DESs and residual biomass and Chlorophyll were extracted into the upper hydrophobic DES layer and Biosilica (80 mg/g) was recovered by simple centrifugation. Extracted Biosilica showed an excellent adsorption capacity of 224.71 mg/g for the removal of methylene blue (MB) dye from water (94.3% up to 88.8 % after 4th consecutive steps). Whereas Chlorophyll extracted in the hydrophobic DES phase exhibited excellent photostability (6 folds greater than conventional solvent) indicating the efficacy of DESs as photoprotector for light-sensitive pigments. This is the first report wherein besides an extractant DES also acted as a good photostabilizer. Additionally, we have replaced the acid-based extraction method for Biosilica with non-toxic DESs.

Comparison of the extractability of organophosphorus flame retardants in landfill media using organic and green solvents

Organic solvents are mainly used in the extraction of organophosphorus flame retardants (OPFRs) because of their availability and having been tested as good extracting solvents for most environmental pollutants. However, organic solvents are toxic, flammable, and costly. Hence, there is an ongoing quest for less hazardous chemicals such as green deep eutectic solvents (DES) that are cheap, recyclable, non-toxic and degradable in the environment, which can be used to extract organic pollutants such as OPFRs in environmental samples. This study assessed the extractability of OPFRs in municipal landfill leachate and sediment, using organic solvents and DES. Of the fourteen targeted OPFRs, 11 (80%) and 7 (50%) were detected in the leachate and sediment samples, using hexane; whereas 14 (100%) and 13 (90%) OPFRs were detected in the same order of samples using DES. The concentrations of OPFRs obtained for the leachate using optimum organic and DES ranged from below the limit of quantification (< LOQ)—516 ± 8.10 ng/L and < LOQ—453 ± 8.10 ng/L respectively. Correspondingly, the concentrations of OPFRs in sediment samples ranged from < LOQ—135 ± 2.89 ng/g dw and < LOQ—395 ± 2.24 ng/g dw, respectively. The results from this study, therefore, highlight the potential of DES to extract more OPFR from complex matrices such as landfill leachate and sediment. This finding infers that green hydrophilic DES can serve as good replacement for organic solvents such as hexane in liquid–liquid extraction (LLE) and solid–liquid extraction (SLE) techniques for landfill leachate and sediment.

In-situ sorbent formation for the extraction of pesticides from honey.

An organic polymer was re-precipitated in solution to use as an adsorbent in dispersive solid-phase extraction of some pesticides from honey samples prior to their determination by high-performance liquid chromatography-tandem mass spectrometry. In this approach, different deep eutectic solvents were prepared using lysine and their ability in elution of the analytes from the adsorbent surface was tested. A diluted honey solution was transferred into a glass test tube and then a solution of polystyrene dissolved in dimethylformamide was injected into the solution. By doing this, polystyrene is re-precipitated in the solution and dispersed in whole parts of it as many tiny particles. Then the mixture was centrifuged and the adsorbed analytes on the particles were eluted using a proper hydrophilic deep eutectic solvent. The central composite design approach was used for the optimization of effective parameters. The limits of detection and quantification were in the ranges of 0.06-0.20 and 0.22-0.69ng/g, respectively. The calibration curves obtained by matrix-matched standard solutions were linear in the range of 0.69-500ng/g with a coefficient of determinations ≥0.9962. The method provided high extraction recoveries (70-99%) and enrichment factors (140-198), and an acceptable precision (relative standard deviations ≤7.1%).