Magnetic Deep Eutectic Solvent Research Articles

Characterization and optimization of ultrasound assisted oxidative desulfurization of a model fuel using a novel magnetic deep eutectic solvent

ABSTRACT In various studies, researchers have utilised different solvents to extract sulfur compounds from the fuels. This paper introduces a novel magnetic deep eutectic solvent employed in the ultrasound-assisted oxidative desulfurisation of dibenzothiophene within a model fuel. The solvent, synthesised at 85°C by combining choline chloride, p-toluene sulfonic acid, and FeCl₃, underwent characterisation through Fourier transform-infrared, Vibrating-sample magnetometer, and Raman spectrometry. Exploration of the key parameters, including oxidant to model fuel volumetric fraction percentage (0.2–0.3), Iron (III) chloride to choline chloride mole fraction (0.1–0.3), and Magnetic deep eutectic solvent to model fuel volumetric fraction (0.2–0.3), was conducted to assess their impact on dibenzothiophene conversion rates. Employing response surface methodology based on central composite experimental design, optimal operational parameters for the ultrasound-assisted oxidative desulfurisation process were identified, resulting in a sulfur removal rate of 98.7%. The findings highlight the solvent sustained efficiency even at higher dibenzothiophene concentrations. Additionally, the solvent paramagnetic properties facilitated an expedited separation from the fuel, leading to the significantly reduced process times.

Evaluation of some sulfonamide antibiotics residues in chicken meat samples using in-syringe counter current homogenous liquid–liquid extraction and magnetic deep eutectic solvent-based dispersive liquid–liquid microextraction and HPLC–DAD

A sample pretreatment method based on the combination of counter current salting-out homogenous liquid–liquid extraction and magnetic deep eutectic solvent-based dispersive liquid–liquid microextraction was developed and employed for the extraction of some sulfonamide antibiotics from chicken meat samples. For this purpose, first, a homogenous solution of acetonitrile and deionized water was passed through a syringe barrel filled sodium chloride and chicken meat sample. By doing so, the fine droplets of acetonitrile were produced and collected on the surface of solution. In the following, this phase containing the extracted analytes was taken and injected into deionized water after mixing with [Choline: 4-chlorophenol]+[FeCl4]- magnetic deep eutectic solvent. Then, the magnetic deep eutectic solvent droplets were separated in the presence of an external magnetic field and injected into high performance liquid chromatography-diode array detector for quantitative analysis. Based on the validation results, low limits of detection (0.15–0.24 ng g−1) and quantification (0.51–0.80 ng g−1), high extraction recovery (67–78 %), and good precision (relative standard deviations ≤ 5.7 %) were obtainable by using the offered method. Finally, the suggested method was employed for the quantification of the studied sulfonamide antibiotics in various chicken meat samples.

Removal of phenolic inhibitor compounds from hydrolysates and post-fermentation broths by using a hydrophobic magnetic deep eutectic solvent

Hydroxymethylfurfural (HMF), furfural (FF), hydroquinone (HQ), and vanillin (VAN) are among the main inhibitors generated during most of biomass pre-treatments prior to fermentation processes. They are recognized as toxic to several fermentative microorganisms and therefore cause a decrease in biohydrogen or biofuel production (after hydrolysis). Moreover, if they are released into aqueous solutions (after fermentation), they can be detrimental to the ecosystem. In this research, a new method for removing these inhibitor compounds from the broth after hydrolysis and fermentation is proposed. A hydrophobic magnetic deep eutectic solvent (HMDES), based on menthol: nonanoic acid in a mole ratio of 2:1 was prepared and magnetized with Fe3O4 nanoparticles and applied for effective sorption and removal of these inhibitors from the broth after fermentation and for biomass hydrolysates. Parameters affecting sorption, such as pH, volume of the inhibitors, initial concentration of inhibitors, volume of HMDES, temperature, stirring speed, and contact time, were studied and optimized. Under optimum conditions, the removal efficiency for HQ, HMF, FF, and VAN was obtained as 92.97, 86.72, 82.86 and 95.12% for the model samples. In addition, the removal efficiency of real samples after hydrolysis and fermentation for HQ, HMF, FF and VAN were higher than 83.3, 71.42, 69.99 and 76.80%, respectively. The studies on HMDES regeneration revealed that the removal efficiency remained constant even after undergoing 13 cycles of regeneration. The mechanism of inhibitor removal suggests that hydrogen bonding or van der Waals interactions may serve as the predominant factor influencing the extraction process.

Simultaneous extraction of polycyclic aromatic hydrocarbons and tetracycline antibiotics from honey samples using dispersive solid phase extraction combined with dispersive liquid-liquid microextraction before their determination with HPLC-DAD

A dispersive solid-phase extraction method combined with dispersive liquid-liquid microextraction was offered for the extraction of four polycyclic aromatic hydrocarbons (anthracene, fluorene, phenanthrene, and pyrene) and tetracycline antibiotics (tetracycline, oxytetracycline, and chlortetracycline) from honey samples, simultaneously. In this work, cobalt-gallic acid bio-metal organic framework was synthesized and 20 mg of it was added into of 10 mL the diluted honey solution to efficiently adsorb the analytes. After vortexing (3 min) and centrifuging, the sorbent particles were eluted with 0.75 mL acetonitrile under vortexing for 3 min. In the following, this phase was mixed with 55 µL [Ch: 4-chlorophenol]+[FeCl4]- magnetic deep eutectic solvent and rapidly injected into deionized water. After separating the extractant phase in the presence of an external magnet and diluting it with the mobile phase, it was injected into a high-performance liquid chromatography-diode array detector. Under optimum extraction conditions, extraction recoveries were in the range of 63–84%. The limits of detection of the opted polycyclic aromatic hydrocarbons and tetracyclines were in the ranges of 0.18–0.26 and 0.25–0.29 ng g−1, respectively. Also, good repeatability (relative standard deviations ≤ 7.5 and 8.3% for intra– (n=6) and inter-day (n=4) precisions, respectively) was obtained. In summary, the validated method was successfully recommended for the determination of polycyclic aromatic hydrocarbons and tetracyclines in various honey samples and pyrene was found in two samples at 5.5 and 12.9 ng g−1. The used bio-metal organic framework has sufficient ability in extraction of different classes of compounds (polycyclic aromatic hydrocarbons and antibiotics) from honey. Performing the microextraction step has direct effect in analysis of the analytes in low concentrations and the use of magnetic solvents, eliminate the use of centrifugation in this step.

Development of ultrasound-assisted dispersive liquid–liquid microextraction based on in situ magnetic deep eutectic solvent for determination of cefixime in biological samples by high-performance liquid chromatography

Development of ultrasound-assisted dispersive liquid–liquid microextraction based on in situ magnetic deep eutectic solvent for determination of cefixime in biological samples by high-performance liquid chromatography

Investigation of vortex assisted magnetic deep eutectic solvent based dispersive liquid–liquid microextraction for separation and determination of vanadium from water and food matrices: Multivariate analysis

A new and simple vortex assisted magnetic deep eutectic solvent dispersive liquid–liquid microextraction procedure (VA-MDES-DLLME) was developed for the determination of vanadium (V) in food and water samples by flame atomic absorption spectrometry (FAAS). In the extraction medium, a bis(acetylpivalylmethane) ethylenediimine (H2APM2en) was used for the complexation of V(V) in sample solution at pH 6. The VA-MDES-DLLME was optimized by different operation parameters, pH level of solution, MDESs volume, vortex time, concentration of complexing agent and samples volume. The accuracy of VA-MDES-DLLME was confirmed by analysis of certified reference materials (CRMs) and standard additional method in respect to real samples. The detection limit, quantification limit and enhancement factor were found 0.3, 1.0 ng mL−1 and 120, respectively. The linearity was confirmed for wide concentration range from 1 to 600 ng mL−1 and relative standard deviation (RSD) is 2.8 %. The multivariate statistical analysis was used for factorial design to explore the effects of extraction parameters on recovery of V(V) and also significant level of variables.

An air-assisted dispersive liquid phase microextraction method based on a hydrophobic magnetic deep eutectic solvent for the extraction and preconcentration of melamine from milk and milk-based products.

In the current research, a fast and sustainable air-assisted hydrophobic magnetic deep eutectic solvent-based dispersive liquid phase microextraction followed by UV-Vis spectrophotometry measurements was optimized for the extraction and determination of melamine in milk and milk-based products. The central composite design was applied for the optimization of factors affecting the recovery of melamine. Quantitative extraction of melamine was achieved using hydrophobic magnetic deep eutectic solvents prepared from a mixture of octanoic acid, aliquat-336, and cobalt(II) chloride. The optimum conditions for extraction were found as follows: 6 extraction cycles, pH 8.2, extraction solvent volume 260µL, and acetone volume 125µL.Interestingly, a centrifugation step was not required to achieve phase separation. Under the optimum conditions, melamine was determined in the linear range of 3-600ngmL-1, the limit of detection (3Sblank/m) of 0.9ngmL-1, and the enrichment factor of 144. The validation of the method was investigated by the analysis of reference materials. Consequently, the method was successfully applied for the analysis of melamine residues in milk and milk-based products.

Magnetic deep eutectic solvent-based dispersive liquid-liquid microextraction for determination of strobilurin fungicides in water, juice, and vinegar by high-performance liquid chromatography.

In this study, a magnetic deep eutectic solvent coupled with dispersive liquid-liquid microextraction using high-performance liquid chromatography (MDES-DLLME-HPLC) was developed to detect strobilurin fungicides. The green hydrophobic MDES synthesized by methyltrioctylammonium chloride, ferric chloride, and heptanoic acid was used as an extraction solvent, which was dispersed by vortex and separated by an external magnetic field. The use of toxic solvents was avoided, and the separation time was reduced. The best experimental results were obtained through single factor and response surface optimization. The method had a good linear relationship with R2>0.996. The limit of detection (LOD) ranged from 0.001 to 0.002mgL-1. The extraction recoveries were 81.9-108.9%. The proposed method was rapid and green, and it has been successfully applied to detection of strobilurin fungicides in water, juice, and vinegar.

Surfactant-enhanced air-agitation liquid-liquid microextraction of polycyclic aromatic hydrocarbons from edible oil using magnetic deep eutectic solvent prior to HPLC determination.

Herein, an air-agitation liquid-liquid microextraction procedure was developed for the extraction of several polycyclic aromatic hydrocarbons from edible oil samples. In this study, the extraction procedure was achieved using a new magnetic deep eutectic solvent as the extraction solvent, in which there was no need for centrifugation. To enhance the rate of extraction of the analytes from the samples, the method was promoted by the use of surfactant addition. The extracted analytes were determined by high-performance liquid chromatography with a diode array detector. The influence of various parameters on the extraction efficiency was studied by response surface methodology using a central composite design. Under optimal conditions, linear calibration curves for the target analytes were achieved in the range of 0.43-250 ng g-1. The limits of detection and quantification were in the ranges of 0.04-0.13 and 0.13-0.43 ng g-1, respectively. The repeatability of the method in terms of intra- and inter-day precision was ≤4.7% and ≤6.7%, respectively. The extraction recovery of the method ranged from 75 to 88%. The obtained results show that the proposed method is efficient for the analysis of the target analytes in various oil samples without obvious matrix effects. Pyrene was found in olive oil at a concentration of 42 ng g-1.

Magnetic deep eutectic solvent-based microextraction for determination of organophosphorus flame retardants in aqueous samples: One step closer to green chemistry

A ferrofluidic hydrophobic deep eutectic solvent-based on dispersive liquid–liquid microextraction combined with gas chromatography-flame ionization detection was developed for preconcentration, separation, and quantification of organophosphorus flame retardants in aqueous samples. The magnetic deep eutectic solvent was prepared by sonicating silica-coated magnetic particles and benzyltriphenylphosphonium bromide-1-undecanol as the carrier liquid. A multivariate strategy containing central composition design and a univariate methodology were employed for optimization of the independent variables effective in the efficiency of sorption and desorption steps, respectively. Method validation study performed under optimal conditions, demonstrates the proper linear range for the analytes calibration curves with the limit of detection the range of 3.0 to 23.0 ng/L and the limit of detection lower than 50.0 ng/L. Intra- and inter-day precision measured at three concentrations for the goal analytes were lower than 5.9 and 8.5 %, respectively. The method intra-day accuracy (96.8–102.0 %) and inter-day accuracy (96.5–103.1 %) illustrate the satisfactory applicability of the proposed method for the analysis of the goal analytes in aqueous samples.

Magnetic deep eutectic solvent-based dispersive liquid–liquid microextraction for enantioselectively determining chiral mefentrifluconazole in cereal samples via ultra-high-performance liquid chromatography

A simple, rapid, and efficient pretreatment method of mefentrifluconazole enantiomers in cereal samples was established by dispersive liquid–liquid microextraction coupled with ultra-high-performance liquid chromatography-diode array detector (UHPLC-DAD). In this study, a novel ternary magnetic deep eutectic solvent (MDES) [octyltrimethylammonium bromide][cobalt chloride][acetic acid] was synthesized as the extractant. Acetic acid was used as the dispersant to promote the in situ dispersion of binary MDES [octyltrimethylammonium bromide][cobalt chloride]. The microdroplets of binary MDES containing mefentrifluconazole were separated by an external magnet. Device-assisted dispersion and time-consuming centrifugation steps were eliminated to ensure simplicity and rapidity of the pretreatment. Good linearity ranging from 0.01 μg g−1 to 2 μg g−1 was obtained. The extraction recovery varied from 82.9 to 95.0%. The limit of detection was 0.003 μg g−1. Finally, this established approach has been applied for the enantioselective detection of chiral mefentrifluconazole in corn, rice, wheat, millet, and sorghum samples.

Hydrophobic magnetic deep eutectic solvent: Synthesis, properties, and application in DNA separation

Isolating high-purity nucleic acids from complex biological samples is critical to nucleic acid analysis. In the current work, four hydrophobic magnetic deep eutectic solvents (HMDESs) were firstly designed and prepared for the extraction of DNA. The conformations of the HMDESs were simulated and H-bonding interactions in the HMDESs were investigated by density functional theory (DFT) calculation. Characterization of HMDESs’ physical (magnetism, density, viscosity and hydrophobicity), and thermal (melting point and decomposition temperature) properties were conducted. Single stranded DNA (ssDNA), double stranded DNA (dsDNA) and DNA sodium salts (stDNA) that were extracted by HMDESs could be quickly collected by an external magnet. Three auxiliary extraction methods, including vortex auxiliary extraction, mechanical shaking auxiliary extraction and ultrasonic auxiliary extraction, were introduced to extract DNA with HMDESs and the extraction efficiencies were evaluated using NanoDrop. Factors that could impact the DNA extraction process, such as HMDESs volume, temperature, time, and pH, were systematically investigated via single-factor experimental analysis. The proposed extraction method can successfully extract DNA from complex matrices and E. coli cell lysate. The DNA extracted by using HMDESs are well suitable for PCR amplifications. The interaction and corresponding binding sites between HMDESs and DNA were investigated by FT-IR and DFT calculation. The extraction mechanisms were discussed: hydrophobic interaction and electrostatic interaction are two main forces driving DNA extraction by HMDESs.

Synthesis of low-viscosity hydrophobic magnetic deep eutectic solvent: Selective extraction of DNA

Fast extraction of high-purity nucleic acid from complex biological sample is the key to downstream nucleic acid analysis. In this work, two low-viscosity hydrophobic magnetic deep eutectic solvents (HMDESs) were synthesized for the selective extraction of DNA. The conformation of the HMDES was simulated by density functional theory (DFT) calculation. Characterization of HMDESs’ physical (magnetism, density, viscosity, and hydrophobicity) properties and thermal (melting point and decomposition temperature) properties were conducted. Based on the HMDESs, a vortex-assisted liquid-liquid micro-extraction (VALLME) DNA method was developed. Single stranded DNA that was extracted by HMDESs could be quickly collected by an external magnet. Factors that could impact the DNA extraction process, such as HMDESs volume, temperature, extraction time, and pH were systematically investigated via single-factor experimental analysis. Under the optimized condition, the proposed extraction method has been demonstrated with the extraction of DNA from a series of complex sample matrices, including metal mixture, protein mixture and E. coli cell lysate. The DNA extracted by using HMDES-based VALLME method was well suitable for PCR amplifications. After extraction, the retained DNAs could be readily recovered by simply using Britton-Robison (BR) buffer. In addition, the interaction and corresponding binding sites between HMDESs and DNA were investigated by FT-IR and DFT calculation. This work provides a new green magnetic solvent and a rapid and environmental-friendly extraction method for the enrichment of DNA and other biological macromolecules.

Application of an in-situ formulated magnetic deep eutectic solvent for the determination of triazine herbicides in rice

In this work, a rapid, convenient, sensitive, and cost-effective in-situ formed magnetic deep eutectic solvent based on a dispersive liquid-liquid extraction method was developed for the determination of triazine herbicides in rice. A novel tetrabutylammonium chloride (TBAC) based magnetic deep eutectic solvent (MDES), [TBAC/ethylene glycol][FeCl4] was generated by means of an simple in-situ reaction of the deep eutectic solvent (DES) with iron chloride in the sample solution. The solvent which has high affinity for target analytes and magnetic ability was successfully employed as an extraction solvent and simplified both the extraction and separation procedure. A series of parameters influencing the extraction efficiency were investigated. Under optimal conditions, calibration curves for the target triazine herbicides were obtained in the ranges of 5–1000 ng g−1, with correlation coefficients greater than 0.9910. The limits of detection (LOD) and quantification (LOQ) were in the range of 1.49–3.10 ng g−1 and 4.96–10.34 ng g−1, respectively. The precision of intra- and inter-day were under 6.2% and 9.6%, respectively, and the precision between laboratories were lower than 7.5%. The accuracy of the method varied from 84.9 to 117.5%. Furthermore, the method showed satisfactory matrix effect and robustness. These results indicate that the technique is suitable for rice sample analysis.

Synthesis of magnetic poly (acrylic acid-menthol deep eutectic solvent) hydrogel: Application for extraction of pesticides

A novel magnetic deep eutectic solvent (DES)-based polymeric hydrogel was synthesized via a facile and rapid (in 4 min) thermal frontal polymerization, using acrylic acid-menthol DES (as a functional monomer), ammonium persulfate (as initiator), and acrylic acid-Fe3O4 nanoparticles (as cross-linker). The hydrogel was characterized by FTIR and FE-SEM techniques and utilized as a sorbent in magnetic solid-phase microextraction coupled with GC–μECD for the determination of 16 pesticides. Significant parameters such as sorbent dosage, desorption conditions, adsorption time, pH, and ionic strength were investigated and optimized. The validation results showed that this polymer could act as an excellent sorbent for pesticides. The LODs were in the range of 0.002–0.120 μg L−1, and the linear range was between 0.003 and 20 μg L−1. The enrichment factors were obtained from 152 to 550. The intra-day (n = 6) and inter-day (n = 4) RSDs were in the ranges of 0.8–6.8% and 2.4–17.3%, respectively. The performance and extraction efficiency of DES hydrogel were compared with those of DES functional monomer. Finally, the optimized method was applied for the determination of pesticides in different real environmental water samples, and the obtained recoveries were in the range of 61.0–120.0%.

Combined magnetic molecularly imprinted polymers with a ternary deep eutectic solvent to purify baicalein from the Scutellaria baicalensis Georgi by magnetic separation

A ternary deep eutectic solvent (DES) was applied as a novel functional monomer for synthesis of molecularly imprinted polymers (MIPs) to separate baicalein from the Scutellaria baicalensis Georgi (S. baicalensis). For rapid separation from the complex systems, modified Fe3O4 particles were used as the magnetic cores to prepare magnetic deep eutectic solvent molecularly imprinted polymers (DES-MMIPs). The prepared DES-MMIPs were characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectra, x-ray diffraction, thermal gravimetric analysis, vibrating sample magnetometer and BET analysis. Moreover, the adsorption capability and selectivity of DES-MMIPs to baicalein were investigated systematically. The results of adsorption experiments demonstrated that DES-MMIPs showed excellent binding capacity to baicalein and the selectivity of DES-MMIPs to baicalein was much higher than that of structure analogues (quercetin, hesperetin and keampferol). Finally, DES-MMIPs were applied in selective extraction of baicalein in the S. baicalensis by magnetic separation. The analysis was conducted by high performance liquid chromatography. The recoveries of baicalein in the S. baicalensis ranged from 91.6% to 99.3%. It had been proven that the DES-MMIPs were an innovative and effective adsorbent for selective recognition and separation of baicalein in complex systems.

Magnetic deep eutectic solvent-based ultrasound-assisted liquid–liquid microextraction for determination of hexanal and heptanal in edible oils followed by gas chromatography–flame ionization detection

Use of a novel magnetic deep eutectic solvent (MDES), consisting of the inexpensive and simple components [choline chloride/para-cresol] [FeCl4] was examined using ultrasound-assisted liquid–liquid microextraction and back-extraction methods to determine hexanal and heptanal in edible oils.

A magnetic nanoparticle catalyzed eco-friendly synthesis of cyanohydrins in a deep eutectic solvent

A short and highly efficient synthesis of cyanohydrins in a recyclable and biodegradable magnetic deep eutectic solvent is described.