Volume Of Deep Eutectic Solvent Research Articles

Optimization of flavonoids extracted from hawthorn （Crataegus pinnatifida） by ultrasonic-assisted deep eutectic solvent

Hawthorn flavonoids have received extensive attention in agriculture, pharmaceutical and food industries due to their rich biological activities. In this study, deep eutectic solvent (DES) was used to extract flavonoids from hawthorn. Under optimal conditions, with a molar ratio of ethylene glycol to choline chloride at 2:1, DES volume fraction 70%, the solid-liquid ratio of 30:1 (mL/g), and an Ultrasound time of 30 min, the yield of hawthorn flavonoids was 57.82 ± 0.04 mg/g. The measured results were consistent with the prediction. After extracting hawthorn flavonoids, DES was recovered by polyamide resin. The recovery rate reached 91.53% ± 0.12%. Finally, HPLC method was used to compare the content and composition of hawthorn flavonoids extracted by DES compared with ethanol. The experimental results showed that DES had a higher yield and a slightly different composition from ethanol-assisted ultrasonic extraction. In conclusion, the deep eutectic solvent has good application prospects in extracting hawthorn flavonoids.

Deep eutectic solvent extraction combined with magnetic bead ligand fishing for identification of α-glucosidase inhibitors from Pueraria lobata.

In this study, a deep eutectic solvent (DES) extraction combined with a magnetic bead ligand affinity analytical method was developed and used for α-glucosidase inhibitor identification from Pueraria lobata. Several critical parameters affecting the analysis performance, including the type of DES, molar ratio, water amount, pH, salt concentration, and volume of DES, were investigated. The selected analytical sample preparation conditions were as follows. The composition of DES is choline chloride-1,4-butanediol (1:3), the water content is 40%, pH is 7.0 and the volume of extraction solution is 2 mL. The obtained sample extraction solution was analyzed directly using α-glucosidase immobilized magnetic beads (GMBs). Three α-glucosidase inhibitors in Pueraria lobata, including puerarin, daidzin, and daidzein, were identified. Luteolin was used as a positive control to evaluate the method's selectivity. Results showed it could selectively bond to the GMBs in the DES. As the affinity analysis was performed directly in a DES, the solution-removing process could be avoided. The intra-day and inter-day precisions of the method are 5.21% and 6.38%, respectively. The solvent amount was 1/50-1/2000 of that used in traditional methods.

Sensitive determination of daunorubicin in plasma of children with leukemia using pH-switchable deep eutectic solvents and HPLC-UV analysis

An environmental friendly, fast, easy and inexpensive liquid-liquid microextraction (LLME) in combination with pH-switchable deep eutectic solvent (DES) method followed by HPLC was investigated for the separation and determination of daunorubicin (DNR) in human plasma samples. For this purpose, first, 9 DESs were prepared based on previous studies and their switchability in aqueous solution was evaluated by changing the pH. Non-switchable DESs were discarded and switchable DESs were used to extract DNR. The parameters affecting the extraction efficiency were optimized (DES type, volume of DES, concentration of KOH, volume of HCl, salt addition and extraction time). After optimizing the conditions and drawing the calibration curve, figures of merit were calculated. Relative standard deviations (%RSDs) based on 7 replicate with 50 μg L−1 of DNR in plasma were 2.7 for intra-day and 4.8 % for inter-day. A wide linear range from 0.15 to 200 μg L−1 was obtained. The detection limit of the method based on signal-to-noise 3 and the quantification limit of the method based on signal-to-noise 10 were 0.05 and 0.15, respectively. After spiking plasma samples with different concentrations of DNR, relative recoveries were obtained in the range of 91.0–107.8 %.

Synthesis and characterization of pH-responsive deep eutectic solvent followed by HPLC for trace determination of bisphenol A in water samples.

A microextraction based on pH-responsive deep eutectic solvent combined with high-performance liquid chromatography was developed for the separation, preconcentration, and determination of bisphenol A in water samples. Five deep eutectic solvents were prepared using thymol (hydrogen bond acceptor) and 6-, 8-, 9-, 10-, and 12-carbon carboxylic acids (hydrogen bond donor), and were used as extraction solvent. Herein, by alkalinizing the environment, phase transition takes place, and by adding acid, phase separation and extraction of analytes occur simultaneously. Some important parameters on the extraction such as deep eutectic solvent type, molar ratio of deep eutectic solvent components, deep eutectic solvent volume, potassium hydroxide concentration, hydrochloric acid volume, extraction time, and salt addition were optimized. Under the optimum conditions, intra- and interday precisions of the method based on seven replicate measurements of 10μg L-1 of bisphenol A in water samples were 2.2% and 4.3%, respectively. The analytical performance of the method showed linearity over the concentration of 0.05-50μg L-1 with the detection limit of 0.02μg L-1 . The accuracy of the method was confirmed by spiking different concentrations of bisphenol A in real water samples and obtaining relative recoveries in the range of 92.5%-105.2%.

Simultaneous Preconcentration of Fast Green FCF and Rhodamine B Using Deep Eutectic Solvent and Determination via High-Performance Thin Layer Chromatography

The aim of the current investigation is the development of a green, quick, easy, and accurate method for simultaneous preconcentration of fast green FCF (FG) and rhodamine B (Rh B) using a deep eutectic solvent (DES). Then, the high-performance thin layer chromatography (HPTLC) technique was used for the determination of analytes. Decanoic acid and tetrabutylammonium bromide were chosen as the components of DES. HPTLC analysis was performed on an aluminum plate silica gel 60 F254. Methanol-ammonia and ethyl acetate were selected as the mobile phase. Scanning of the plates was accomplished by scanner 3. Effective parameters on the preconcentration process such as concentration of salt, volume of DES, stirrer time, and pH were investigated via central composite design (CCD). Data validation demonstrated good repeatability. The limit of detection for FG and Rh B was obtained as 0.08 and 0.01 µg·mL−1, respectively. The enrichment factor for FG and Rh B was achieved as 7.43 and 10.77, respectively. The linear ranges for FG and Rh B were acquired as 0.10–1.20 and 0.05–1.20 µg·mL−1, respectively. The preconcentration factor for both analytes was 21.66. Finally, the proposed method was successfully used for the quantitation of FG and Rh B in pastille and lipstick.

A novel deep eutectic solvent as an extractant for the determination of bisphenol compounds in edible oils by high-performance liquid-phase fluorescence detection

In this study, an efficient, low-cost and environmentally friendly deep eutectic solvent (DES) was prepared using methanol and betaine, which was then employed as an extractant to detect BPA and BPF in several edible oils by high performance liquid chromatography-fluorescence detection (HPLC-FLD) with good results. The electrostatic potentials of methanol, betaine, water and BPs were analyzed by quantum chemical computational techniques to explain the mechanism of DES extraction. Several important parameters affecting the extraction efficiency, composition, volume and extraction time of DES were optimized. The optimum conditions for the use of DES were the molar ratio of 1:30 (betaine: methanol), the volume of DES of 200 μL and the extraction time of 1.5 min. The results of the method evaluation showed a wide linear range (0.01–0.8 μg g−1) and a high linear correlation coefficient (R2 ≥0.994). The limit of detection (LOD) and limit of quantification (LOQ) values ranged from 1.65 to 2.92 ng g−1 and 5.45–9.64 ng g−1, respectively. The greenness of the assay was evaluated by applying the green analytical procedure index method, and the results showed that the experimental method has the advantages of simple sample pre-treatment and low amount of waste generated during the assay. The experimental method has potential applications in the field of the detection of bisphenol compounds in edible oils.

Deep Eutectic Solvent-Based Dispersive Liquid-Liquid Microextraction Coupled with LC-MS/MS for the Analysis of Two Ochratoxins in Capsicum.

Ochratoxins, a common class of mycotoxin in capsicum, and techniques and methods for the determination of mycotoxins in spices have been increasingly developed in recent years. An innovative and eco-friendly method of dispersive liquid-liquid microextraction (DLLME) was demonstrated in this study, based on a synthesized deep eutectic solvent (DES) combined with LC-MS/MS, for the quantification and analysis of two ochratoxins in capsicum. The DES-DLLME method parameters entail selecting the DES type (thymol:decanoic acid, molar ratio 1:1) and DES volume (100 μL). The volume of water (3 mL) and salt concentration (0 g) undergo optimization following a step-by-step approach to achieve optimal target substance extraction efficiency. The matrix effect associated with the direct detection of the target substance in capsicum was significantly reduced in this study by the addition of isotopic internal standards corresponding to the target substance. This facilitated optimal conditions wherein quantitative analysis using LC-MS/MS revealed a linear range of 0.50-250.00 µg/mL, with all two curves calibrated with internal standards showing correlation coefficients (r2) greater than 0.9995. The method's limits of detection (LODs) and limits of quantification (LOQs) fell in the ranges of 0.14-0.45 μg/kg and 0.45-1.45 μg/kg, respectively. The method's spiked recoveries ranged from 81.97 to 105.17%, indicating its sensitivity and accuracy. The environmental friendliness of the technique was assessed using two green assessment tools, AGREE and complexGAPI, and the results showed that the technique was more in line with the concept of sustainable development compared to other techniques for detecting ochratoxins in capsicum. Overall, this study provides a new approach for the determination of mycotoxins in a complex food matrix such as capsicum and other spices using DES and also contributes to the application of green analytical chemistry methods in the food industry.

Deep eutectic solvent dispersive liquid–liquid microextraction methods for the analysis of chlorophyll natural colorant (E140) via microwave assisted sample preparation

In the current research paper, extraction and analysis of chlorophyll, one of the bioactive compounds that is usually utilized as natural pigments (E140) and obtained from many leafy green plants and seaweeds, have been carried out via deep eutectic solvent-based dispersive liquid–liquid phase microextraction (DES-UA-DLLME) from plants and food pruducts. The DES-UA-DLLME method was developed by utilizing deep eutectic solvent (DES) which was prepared by heating process with a 1:1 ratio of choline chloride and urea (ChCl: U). Analytical parameters such as pH, DES volume, sample volume, centrifugation and mixing time, DES type, matrix effect, etc. were optimized to ensure the extraction efficiency of chlorophyll. The limit of detection (LOD), limit of quantification (LOQ), intra-day and inter-day relative standart devision (RSD) were found as 0.007 µg/mL, 0.023 µg/mL, 1.3 %, and 1.9 %, respectively. The accuracy of the method was tested with water sample addition/recovery studies. The DES-UA-DLLME method has been applied to food, water, and plant samples. The food products and plants were prepared with the help of ultrasonic and microwave extraction for spectrophotometric analysis of chlorophyll. According to literature survey, the DES-UA-DLLME method and the MWAE method combination was used to the first time for extraction of chlorophyll (E140) from plants.

Effervescent tablet-assisted deep eutectic solvent based on magnetic nanofluid for liquid phase microextraction of tyrosine kinase inhibitors in plasma samples by high-performance liquid chromatography.

Tyrosine kinase inhibitors (TKIs) are efficient anti-cancer drugs. The analysis of TKIs in the treatment of cancer is important to achieve the highest anti-cancer effects with minimal toxicities. Herein, we report an efficient effervescent tablet-assisted deep eutectic solvent based on nanofluid (ETA-DES-NF) combined with HPLC-UV for the determination of three anti-cancer drugs (erlotinib, imatinib, and nilotinib) in human plasma samples. In this method, a magnetic nanofluid composed of deep eutectic solvent (DES) and Fe3O4@SiO2 nanoparticles was used as an extraction solvent. The deep eutectic solvent acted as a carrier and stabilizer for Fe3O4@SiO2 nanoparticles. A tablet was used in the nanofluid for dispersion. The effervescent tablet was implemented to generate in situ CO2 and provide the effective dispersion of the sorbent into the sample solution for diminishing the extraction time and improving the extraction efficiency. Moreover, the magnetic nanofluid enhanced phase separation efficiency without centrifugation to collect the organic solvent. The synthesized nanofluid was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). The impact of main parameters, including the type and volume of DES, the composition of the tablet, the composition of the nanofluid and the composition of eluent, were optimized. According to the optimized conditions, the limits of detection (LODs) and the limits of quantitation (LOQs) were from 0.5-0.8 to 1.5-2.4μg L-1 for imatinib, erlotinib, and nilotinib, respectively. The intra-day and inter-day relative standard deviations (RSD% n = 5) were determined to be 3.1-5% and 6.4-7.5%, respectively. The developed method displayed high sensitivity, low consumption of solvent, low cost, simplicity, high recoveries, short extraction time, and good repeatability for determination of three anti-cancer drugs in human plasma samples.

A green ternary polymeric deep eutectic solvent used in dispersive liquid-liquid microextraction technique for isolation of multiclass pesticides in fruit juice samples

A green dispersive liquid-liquid microextraction procedure based on a ternary polymeric hydrophobic deep eutectic solvent (DES) for monitoring multi-residue pesticides in eleven various fruit juices was developed before Gas Chromatography coupled with micro-Electron Capture Detector (GC-µECD). Six ternary polyethylene glycol (PEG)-based DESs were synthesized, and their extraction efficiency was evaluated. Among these DESs, [thymol]:[polyethylene glycol]:[acetic acid] (1:2:2) showed the highest signal intensity. Moreover, three other binary PEG-based DESs and a non-polymeric DES were also synthesized and compared to the previous DES. The extraction yield obtained by polymeric one was much higher than non-polymeric. Some significant parameters influencing the extraction efficiency including the type and volume of DES (extraction solvent), disperser solvent, pH, and ionic strength were optimized as follows: [Thy]:[PEG]:[HOAc] (1:2:2), 400 µL of DES, ACN as disperser solvent (700 µL), no pH adjustment and no salt addition. The DES was characterized by ATR-FTIR and (1H and 13C) NMR spectroscopy. Under the optimized conditions, the limits of quantification, the linear ranges and extraction recovery were 0.009–0.182 µgL−1 0.003–50.0 µgL−1, 67.9–108.4%, respectively. The enrichment factors were 11–170. Intra-day and inter-day RSDs% were 1.4–5.1% and 2.0–12.6%, respectively. This method was applied for analyzing pesticide residues in eleven fruit juices, and the pre-concentration factor and relative extraction recoveries were in the range of 12–169 and 71–108%, respectively.

A green deep eutectic solvent based dispersive liquid-liquid microextraction for the quantitative analysis of 21 polychlorinated biphenyl metabolites in food of animal origin using injector port silylation-gas chromatography-tandem mass spectrometry

An analytical method was developed for the quantitative determination of 21 polychlorinated biphenyls (PCBs) metabolites (17 were -OH, 1 -MeO, and 3 were MeSO2) in foods of animal origin using deep eutectic solvent (DES) based dispersive liquid-liquid microextraction followed by injector port silylation-gas chromatography-tandem mass spectrometry. The type of DES (thymol: camphor, 1:1 molar ratio) and optimum volume of DES (300 µL), pH (7.0), and disperser solvent (acetonitrile) were optimized to attain the maximum extraction efficiency. The limit of detection, limit of quantification, and percent recovery were found to be in the range of 0.12–0.23 ng/mL, 0.40–0.76 ng/mL, and 80.1–111.4%, respectively. The expanded uncertainty was observed to be in the range of 7.2–22.8% for the targeted analytes. The proposed method was applied to real food samples (milk, meat, fish, and egg) and the levels were found to be in the range of 0.64–32.14 ng/g. This is first of its kind method using green solvent based method for the analysis of PCB metabolites (-OH, MeO, and MeSO2) and will find extensive application in routine testing for foods of animal origin.

Multi-response optimization of a deep eutectic solvent‑based microextraction method for the simultaneous extraction of twenty organochlorine pesticides for monitoring in various water samples

This study investigates the application of a relatively hydrophobic deep eutectic solvent (DES) for ultrasound-assisted emulsification-microextraction of twenty organochlorine pesticides from environmental water samples before determination by gas chromatography equipped with a micro-electron capture detection. To find the highest global extraction efficiency, the central composite design combined with the desirability function (DF) approach was utilized for multi-response optimization of effective parameters, including DES volume, pH, salt concentration, and sonication time. DES was prepared by combining choline chloride as a hydrogen bond acceptor and 1-phenylethanol as a hydrogen bond donor in a mole ratio 1:4. The optimum conditions corresponding to 0.888 in the DF were pH 10.10, DES volume of 73 µL, salt concentration of 17.44% (w/v), and sonication time of 7.36 min. The analytical performance of the method was evaluated under optimum conditions and a wide linear range (0.05–30 ng/mL) with good linearity (R2 > 0.9967), low limit of detection (3.5–33 pg/mL), high enrichment factors (151.1–616.3), and good extraction recoveries (27.2–98.6%) were obtained. The potential of using the method to determine OCPs in four real water samples was proved through high relative recoveries values. The Green Analytical Procedure Index (GAPI) tool was used to evaluate the method's greenness, which confirms the superior eco-friendship of the method compared to other methods.

Development of a liquid-phase micro-extraction based on the use of deep eutectic solvent for pre-concentration and measurement of malachite green in water and fish samples

ABSTRACT An easy-to-use, fast, and efficient liquid phase micro-extraction was developed based on the use of a deep eutectic solvent to extract malachite green (MG) from the water and fish samples. Herein, a green solvent including choline chloride (ChCl): phenol (PhOH) with a ratio of 1:3 was tested as an extractant phase in dispersive liquid-liquid micro-extraction for MG extraction followed by spectrophotometric determination. A 15 ml portion of the sample solution was used, and various effective parameters for the deep eutectic solvent (DES) in the micro-extraction models, such as deep eutectic solvent volume, salt concentration, time of micro-extraction, and pH were assayed and optimised. The best micro-extraction cases were collected by 186 microlitres of deep eutectic solvent, a salt concentration of 1.2% W/V, a pH of 4.5 of samples, and a micro-extraction time of 5.5 min. Multi-layer perceptron was also used to train the network. R2 and mean square error (MSE) are 0.9965 and 1.8968 respectively. In optimal values, the linear range of malachite green was achieved to be 10–350 ng mL−1. Enrichment factor and LOD were reached to be 60 and 2 ng mL−1, respectively. The %RSD of 100 ng mL−1 of malachite green was 2.6%. Finally, this method allows the measurement of MG in fish and aqueous samples with favourable recoveries.

An ultrasound assisted modified solid phase micro-extraction technique for enrichment of cadmium and lead in aqueous extract of coal gangue soil samples

The present study was carried out to develop a green and novel ultrasonically modified solid phase micro-extraction method (Um-SPµE) to quantify the cadmium (Cd2+) and lead (Pb2+) in acidic water extract (pH < 6.5) of coal gangue soil (CGS) samples collected from the block II of Thar coal field Sindh Pakistan. The 8-hydroxyquinoline (8-HQ) embedded benzophenone allows quantitative enrichment of the Cd2+ and Pb2+ at pH ∼ 6.0. The ultrasonic energy applied to enhance the dissolution/extraction of hydrophobic complex of Cd2+ and Pb2+ in deep eutectic solvent (DES), which synthesized by mixing of zinc chloride and acetamide at 1:2 mol ratios. The extraction capability of DES was enhanced by addition of a nonionic surfactant (Triton X-114) to improve the phase transfer ratio, to notably enhance the recovery of hydrophobic complex of Cd2+ and lead Pb2+. There were various factors (pH, concentration of ligand, adsorbent quantity, volume of DES and nonionic surfactant, and sonication time), effecting the enrichment factor, preconcentration and % recoveries of both metals; were optimized. The certified reference materials and spiking recovery test were applied to real samples in order to check precision and validity of the developed methodology. The % recoveries of both selected metals were found to be > 98% by applying developed method (p < 0.05).

Hydrophilic deep eutectic solvent based microextraction procedure for the determination of four paraben preservatives in vitamin D for babies: A green approach

In this study, an easily available, sensitive, and fast hydrophilic deep eutectic solvent-liquid phase microextraction method developed using deep eutectic solvent (DES) as a green solvent for the determination and microextraction of paraben (methyl, ethyl, propyl, and butyl) preservatives in vitamin D for babies. The highest yield for extraction recovery was obtained using DES consisting of a 1:4 M ratio of choline chloride and acetic acid. Moreover, various optimization parameters such as DES volume, DES type, sample volume, and centrifugation time were investigated in order to develop a real sample specific microextraction method. Relative standard deviation values were 0.92%-2.87%, the detection limit was 0.194–0.254 µg/mL, and extraction recovery values were between 87.40% and 102.98%. The method developed in this study was successfully applied to 5 different babies in vitamin D for babies obtained from pharmacies for the determination of methyl, ethyl, propyl, and butylparaben. As far as we know, it is the first study conducted both in terms of the determination of paraben preservatives in vitamin D for babies and in terms of the fact that DES used in this study is used for the first time in vitamin D for babies.

A natural hydrophobic deep eutectic solvent-based microextraction method integrated with a spectrofluorimetric technique for the determination of daclatasvir as a direct-acting hepatitis C antiviral drug in plasma samples

An ultrasound-assisted emulsification microextraction method based on a natural hydrophobic deep eutectic solvent (USAEME-HDES) was developed for extraction and preconcentration of daclatasvir, a hepatitis C virus inhibitor, from plasma samples prior to spectrofluorimetric measurement. To make the deep eutectic solvent (DES) compatible with the fluorescence device, fatty acids were used as components of DES that can simultaneously act as hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA). Various parameters, such as the solvent effect on the fluorescence spectrum and the composition and ratio of DES, were investigated and optimized. Other parameters, including pH, DES volume, sonication time, and NaCl concentration, were investigated and optimized using the central composite design combined with the desirability function. Under optimal conditions, compared to other methods, this method had a wide linear range (5–600 ng/mL) with a good coefficient of determination (0.9985) and a low limit of detection (1.42 ng/mL). Drug analysis results in the plasma samples showed that the method has good accuracy. Finally, the Green Analytical Procedure Index (GAPI) tool was used to evaluate the greenness of the method, which demonstrates our method's superior eco-friendship in comparison to other reported methods.

Preparation of a hydrophobic deep eutectic solvent and its application in the detection of quinolone residues in cattle urine.

Enrichment for the detection of quinolone residues is usually cumbersome and requires large amounts of toxic organic reagents. Therefore, this study synthesized a low-toxicity hydrophobic deep eutectic solvent (DES) with DL-menthol and p-cresol, which was then characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and thermal analysis. A simple and rapid vortex-assisted liquid-liquid microextraction method was developed based on this DES for the extraction of eight quinolones from cattle urine. The optimal extraction conditions were screened by examining the DES volume, extraction temperature, vortex time, and salt concentration. Under the optimal conditions, the linear ranges of the eight quinolones were 1 ~ 100μg/L with good linearity (r2 was 0.998 ~ 0.999), and the limits of detection and quantification were 0.08 ~ 0.30μg/L and 0.27 ~ 0.98μg/L, respectively. The average extraction recoveries of spiked cattle urine samples were 70.13 ~ 98.50% with relative standard deviations below 13.97%. This method can provide a reference for the pre-treatment of quinolone residue detection.

Utilizing deep eutectic solvent for facile, selective and sustainable sequestration of plutonium

In the recent surge of green and cheap energy for future generation; nuclear industry is going to play a pivotal role and reprocessing of nuclear fuel through safe and systematic approach is the key. In that direction recent literature has shown that there is lack of better and improved methods towards efficient extraction of highly radiotoxic and hazardous plutonium from nuclear waste. Herein, we have utilized a greener and cost effective indigenously synthesized deep eutectic solvent (DES) for the selective extraction of plutonium from (Am, Pu, U) waste. The maximum D value achieved for Pu was 67.42 at 5 mol L−1 HNO3 media and the equilibrium uptake capacity was found to be 107.28 ± 5 μg of Pu/g of C12DES. This was followed by solidified floating organic drop micro-extraction (SFODME) technique for its quantification. High radiation stability of this DES (upto 750 kGy) highlighted its great potential in nuclear fuel reprocessing. Several other reprocess parameters were studied and optimized such as DES volume, alkyl chain length attached to hydrogen bond acceptor (HBA), actinide concentration and speciation and its acidity to achieve best extraction of plutonium ion form the waste stream. Regeneration capability and reusability of the DES employing stripping agents gave encouraging results as 95% of Pu could be stripped in a single cycle using 1 M hydroxylamine hydrochloride as the stripping agent. The developed method was applied for recovery and quantification of Pu from real samples, viz. (U,Pu) Carbide fuel solution, radioactive research waste and synthetic dissolver solution. We believe this work is a way forward in resolving a variety of issues that exist in health physics and reprocessing laboratories of nuclear installation pertaining to selective and efficient extraction of Pu (IV).

Natural deep eutectic solvent based ultrasound assisted liquid-liquid micro-extraction method for methyl violet dye determination in contaminated river water

Simple and green natural deep eutectic solvent (NADES) based ultrasound assisted liquid-liquid micro-extraction (UA-LLME) method was developed for extraction and determination of methyl violet dye in contaminated river water samples using UV/Vis spectrophotometry. Choline chloride - decanoic acid based natural deep eutectic solvent was used for extraction. Important analytical parameters like pH, deep eutectic solvent volume/phase ratio, tetrahydrofuran volume, sonication time, and temperature were optimized. Limit of detection (LOD) and limit of quantification (LOQ) were 2.20 μg/L and 7.34 μg/L respectively. Relative standard deviation was 2.35–3.21%. Linearity of method was investigated in a concentration range 10–400 μg/L. Enrichment factor was calculated as 20. For 20 mL sample, the optimized parameters were as deep eutectic solvent volume 1.5 mL, tetrahydrofuran volume was 0.6 mL, pH = 6, sonication time 2 min. The optimized method was tested for extraction of methyl violet in real water samples confirming its applicability in routine environmental analysis.

5-Hydroxymethylfurfural synthesis from fructose over deep eutectic solvents in batch reactors and continuous flow microreactors

In this work, a deep eutectic solvent (DES) composed of choline chloride (ChCl) and ethylene glycol (EG) was prepared and applied for the conversion of fructose to 5-hydroxymethylfurfural (HMF), catalyzed by HCl in both laboratory batch reactors and continuous flow microreactors. The effects of reaction temperature, batch time, catalyst loading and molar ratio of ChCl to EG on the fructose conversion and HMF yield were first investigated in the monophasic batch system of ChCl/EG DES. To inhibit HMF-involved side reactions (e.g., its polymerization to humins), methyl isobutyl ketone (MIBK) was used as the extraction agent to form a biphasic system with DES in batch reactors. As a result, the maximum HMF yield could be enhanced at an MIBK to DES volume ratio of 3:1, e.g., increased from 48% in the monophasic DES (with a molar ratio ChCl to EG at 1:3) to 63% in the biphasic system at 80°C and 5 mol% of HCl loading. Based on the optimized results in batch reactors, biphasic experiments were conducted in capillary microreactors under slug flow operation, where a maximum HMF yield of ca. 61% could be obtained in 13 min, which is similar to that in batch under otherwise the same conditions. The slight mass transfer limitation in microreactors was confirmed by performing experiments with microreactors of varying length, and comparing the characteristic mass transfer time and reaction time, indicating further room for improvement.Highlights• The efficient fructose conversion to HMF in deep eutectic solvents was achieved in batch reactors and microreactors.• An HMF yield over 60% could be obtained at a fructose conversion above 90% in both reactors at 80°C within 14 min.• The HMF yield was enhanced from 48% in the monophasic ChCl/EG system to 63% in the DES-MBIK biphasic system in batch.• A slight mass transfer limitation was found in the biphasic slug flow microreactor.Graphical