Eutectic Solvent-based Dispersive Liquid-liquid Microextraction Research Articles

Natural deep eutectic solvent-based dispersive liquid-liquid microextraction of pesticides in drinking waters combined with GC-MS/MS detection

The current research aims to develop a new analytical method applying a dispersive liquid-liquid microextraction (DLLME) assisted by vortex and using an environmentally friendly extractant for the preconcentration of organochlorine and organophosphorus pesticides followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. The extractant (i.e., natural deep eutectic solvent (NADES)) is safe, cheap, biodegradable and can be prepared by simply mixing DL-menthol and decanoic acid (molar ratio 2:1). The main experimental factors affecting the extraction of all analytes evaluated (19 organochlorine and organophosphorus pesticides) have been optimised using a multivariate analysis consisting in two steps: a Plackett-Burman design followed by a central composite design (CCD). Seven experimental factors have been evaluated: (i) sample volume; (ii) NADES volume; (iii) sample pH; (iv) extraction time; (v) centrifugation time; (vi) centrifugation speed; and (vii) ionic strength (NaCl %, w v−1). For the significant variables, the optimum values were 10 mL sample and 45 μL NADES. No pH adjustment as well as addition of NaCl were needed. The other variables were set at 3 min extraction time, 5 min centrifugation time and 900×g centrifugation speed, respectively. Under the optimised extraction conditions, the limit of quantification (LOQ) values ranged between 0.2 and 78 ng L−1 for all analysed pesticides. Furthermore, the proposed analytical method has been successfully applied to drinking water (bottled spring water). The recovery study (n = 3) has been evaluated at 0.1, 1.0 and 5.0 μg L−1 spiking levels, obtaining relative recovery values within the range of 70 % and 117 % and RSD values between 1 % and 20 % for all the analytes studied, except for p,p-DDT (56–77 % in high conductivity water samples).

Determination of Fe, Cu, and Pb in edible oils using choline chloride:ethylene glycol deep eutectic solvent-based dispersive liquid-liquid microextraction associated with microwave-induced plasma optical emission spectrometry

A new simple, fast and environmentally friendly deep eutectic solvent based dispersive liquid-liquid microextraction (DES-based DLLME) methodology assisted by vortex is presented for the separation and preconcentration of three elements (i.e., Fe, Cu and Pb) from edible oil samples (i.e., soybean, sunflower, rapeseed, sesame, and olive oil) prior to the determination by microwave-induced plasma optical emission spectrometry (MIP-OES). The deep eutectic solvent selected as extractant (i.e., choline chloride and ethylene glycol, 1:2) is synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (1H NMR) and differential scanning calorimetry (DSC), and the extraction conditions are optimized by a two steps experimental design. Under the optimum extraction conditions (i.e., diluted sample weight: 8.6 g; DES volume: 100 μL; extraction time: 1 min; centrifugation time and speed: 3 min and 3000 rpm; and dispersion system: vortex) the analytical method presents excellent linearity (i.e., R2 values higher than 0.99) in the range 10–500 μg kg−1, repeatability (i.e., CV values lower than 9.2%), and limits of detection (LOD) values of 3, 2 and 0.7 μg kg−1 for Pb, Fe and Cu, respectively. None of the analytes displayed amounts over the upper limit permitted by law, and recovery values of all analytes evaluated in the different samples using external standard calibration were close to 100%, which excludes significant matrix effects. Finally, AGREEprep metric has been used to evaluate the method greenness (final score of 0.47) and it has been compared successfully with previous publications for the same type of analytes and matrices.

Sensitive method for determination of benzoic acid in beverages and food samples using air–assisted hydrophobic deep eutectic solvent-based dispersive liquid-liquid microextraction

A simple, reliable and rapid air–assisted hydrophobic deep eutectic solvent-based dispersive liquid–liquid microextraction (AA-HDES-DLLME) was developed for analysis of benzoic acid in various beverages and food samples. The final determination stage was performed via UV–visible spectrophotometry. The key parameters (extraction time, HDES type and volume, dispersant volume, pH and sample volume) of the AA-HDES-DLLME method were optimized in detailed using Box–Behnken design. Analysis of variance was used for statistical analysis. Under the optimized conditions, limit of detection (12.1 μg L−1), limit of quantification (40 μg L−1), linearity range (40–1000 μg L−1), and preconcentration factor (140) were determined. While the accuracy of the AA-HDES-DLLME method was investigated with the standard addition approach, its precision was investigated with intraday/interday studies. The method proved to be effective for routine analytical practice for a wide variety of samples. The novelty of the AA-HDES-DLLME method is that it enables the extraction of benzoic acid without the need for heating or centrifugation steps. In this way, the AA-HDES-DLLME method enabled selective extraction of benzoic acid in a shorter time and using less energy compared to similar studies.

Novel reusable and switchable deep eutectic solvent for extraction and determination of curcumin in water and food samples

For the first time, a fast and easy extraction method based on a unique reusable and switchable deep eutectic solvent (made of octylamine, succinic acid, and water as precursors) was presented and utilized for the microextraction and determination of curcumin as a model analyte. The main factors used to induce a phase transition in the as-prepared deep eutectic solvent were solutions of NaOH and HCl. Among the standout characteristics of the suggested deep eutectic solvent are the removal of toxic organic solvents like THF, the lack of a need for centrifugation, and the ability to be reused in subsequent extractions. The influence of effective parameters (i.e., proportions of deep eutectic solvent structure components, volume of prepared deep eutectic solvent, volume and concertation of NaOH, volume of HCl, and salt effect) on the extraction procedure were investigated. The calibration curve also was linear in the range of 35–500 μg L−1 with coefficients of determination (R2) of 0.9976. Limit of detection (S/N = 3) 10.0 μg L−1, the limit of quantification (LOQ) of 35.0 μg L−1, the relative standard deviations (RSDs %) composed of intra-day RSD (4.7) and inter-day RSD (6.4), preconcentration factor of 40.0, enrichment factor of 38.68, and relative recovery of 92.6%–100.3 % were achieved. The reusable and switchable deep eutectic solvent based-dispersive liquid-liquid microextraction technique was proficiently employed to expedite easy and fast extraction of curcumin from water and food samples.

Deep eutectic solvent-based dispersive liquid-liquid microextraction coupled with HPLC and central composite design for biological monitoring of hippuric acid and methyl hippuric acid in urine

Exposure assessment of toluene and xylene as two hazardous compounds in occupational settings are great of importance. Hippuric acid (HA) and methyl hippuric acid (MHA) are common urinary metabolites for biological monitoring of toluene and xylene exposure, respectively. In this study a dispersive liquid–liquid microextraction (DLLME) method based on a deep eutectic solvent (DES), was suggested to determine the urinary MHA and HA simultaneously. Optimizations of all parameters affecting the DLLME-DES were done using response surface methodology. In obtained optimized conditions, a linear calibration range of 0.024–20 µg mL−1 for HA and 0.033–20 µg mL−1 for MHA were achieved and R2 was above 0.99 for these two metabolites. The detection limit of HA and MHA was 0.008 and 0.010 µg mL−1 respectively. The quantification limit was reported as 0.024 and 0.033 µg mL−1 for HA and MHA respectively. The suggested analytical technique was used for quantitation of target biomarkers in urine samples of occupational workers with high accuracy (97–103.6% for HA and 92–104% MHA) and precision (RSD ≤ 4.5% for HA (RSD ≤ 6.2% for MHA). Applying the proposed method for urine sample analysis of exposed-workers and comparing with the standard method (National Institute for Occupational Safety & Health standard method) showed that HA and MHA can be pre-concentrated and quantified by a simple, fast and environmental friendly method.

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.

Trace determination of triazine herbicides in fruit and vegetables using novel hydrophobic deep eutectic solvent-based dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet.

In the present research, a novel hydrophobic deep eutectic solvent-based dispersive liquid-liquid microextraction technique was established and combined with high-performance liquid chromatography-ultraviolet for the determination of triazine herbicides in fruit and vegetable samples. A deep eutectic solvent was synthesized using l-menthol as a hydrogen bond acceptor and ethylene glycol as a hydrogen bond donor and used as a green extractant. The characterization of deep eutectic solvent was investigated by Fourier-transform infrared, nuclear magnetic resonance, and thermogravimetric analysis. Under the optimum conditions, relative standard deviation values for intra-day and inter-day of the method based on seven replicate measurements of 50.0μg/kg of triazines were in the range of 2.8%-5.5% and 3.7%-7.2%, respectively. The calibration graphs were linear in the range of 3.0-500μg/kg and the limits of detection were in the range of 1.0-2.0μg/kg. The relative recoveries of different fruit and vegetable samples that have been spiked with two levels of target compounds were 91.5%-109.8%. The method has good linearity, sensitivity, accuracy, and precision. It is also environmentally friendly and was successfully used to determine the concentrations of triazines in fruit and vegetable samples.

Determination of aromatic amines in environmental water samples by deep eutectic solvent-based dispersive liquid-liquid microextraction followed by HPLC-UV

This study reports a deep eutectic solvent based dispersive liquid-liquid microextraction (DES-DLLME) to extract aromatic amines (4-chloroaniline, 3-nitroaniline, 2-naphtylamine) in environmental water samples before their HPLC-UV determination. The hydrophobic deep eutectic solvent (DES) was prepared by mixing bis(2-ethylhexyl) phosphate (BEHP) as a hydrogen bond acceptor and phenol as a hydrogen bond donor. Affecting factors on the extraction of the aromatic amines were investigated and optimized. Optimum conditions were: DES type: BHHP-Ph ratio: 1 to 2; pH of solution: 8.0; DES volume: 80 µL, salt amount: 10% (w/v). Under optimum conditions, the developed method showed a wide linear range of 0.2–200 µg L−1 (R2 ≥ 0.99) with satisfactory recoveries (≥90.0%). The limit of detections (LODs) and limit of quantifications (LOQs) were in the range of 0.07–0.17 µg L−1 and 0.2–0.5 µg L−1, respectively. The enrichment factors were 170, 180 and 190 for 4-chloroaninile, 3-nitroaniline, 2-naphtylamine, respectively. Based on obtained results, the proposed method is straightforward, efficient, sensitive, and eco-friendly for the extracting and determining of the aromatic amines in environmental water samples.

Hydrophobic Eutectic Solvent-Based Dispersive Liquid-Liquid Microextraction Applied to the Analysis of Pesticides in Wine.

A green solvent-based DLLME/HPLC-MS method for the determination of 19 pesticides in wine samples has been developed. The extractant solvent is a hydrophobic eutectic mixture composed of L-menthol and butylated hydroxytoluene in a molar ratio of 3:1. The endogenous ethanol of wine has been used as dispersive solvent, in order to avoid the solidification of the extracts under 19 °C. The mobile phase composition, the elution gradient and the sample injection volume were optimized in order to make this hydrophobic mixture compatible with conventional reversed phase chromatography and electrospray ionization. The method was validated in matrix, using a wine free from the target compounds. Average recovery as high as 80%, precision between 3 and 14%, and limits of detection and quantification much lower than the maximum residue levels (MRLs) for grapes and wines fixed by the EU regulation, make this multiresidue method fitted for the purpose, with the further advantages of being quick, cheap and in compliance with the green analytical chemistry. From the analysis of 11 commercial wines it was found that just in a bio sample the target compounds were not detectable or lower than quantification limit; as for the other samples, the most widespread and abundant pesticides were methoxyfenozide and boscalid, but their levels were much lower than the relative MRLs.

Ultrasound-Assisted Dispersive Liquid–Liquid Microextraction (DLLME) Based on Solidification of Floating Organic Drop Using a Deep Eutectic Solvent for Simultaneous Preconcentration and Determination of Nickel and Cobalt in Food and Water Samples

Ultrasound-assisted deep eutectic solvent-based dispersive liquid-liquid microextraction (UA-DES-DLLME-SFO) was employed with the solidification of floating organic drop to simultaneously preconcentrate and determine nickel and cobalt in food and water by flame atomic absorption spectrometry (FAAS). 2-(5-Bromo-2-pyridylazo)-5-(diethylamino) phenol (5-Br-PADAP) was employed as the chelating agent, while decanoic acid and dl-menthol were employed as deep eutectic solvents. The influence of extraction solvent type and volume, chelating agent content, pH, ionic strength, and ultrasonication duration was assessed on the microextraction efficiency. Moreover, analytical figures of merit of the approach were determined. The optimal condition resulted in detection limits of 0.3 µg/L and 0.4 µg/L, quantification limits of 1.1 µg/L and 1.3 µg/L, and preconcentration factors of 50 for Ni and Co, respectively. Relative standard deviations (n = 10) for 50.0 µg/L nickel and cobalt were 2.3% and 2.5%, respectively. The developed technique was employed to simultaneously extract and determine nickel and cobalt contents of food and water samples.

Combination of temperature-assisted ternary phase homogenous liquid-liquid extraction with deep eutectic solvent-based dispersive liquid-liquid microextraction for the extraction of phytosterols from cow milk and cream samples.

A three-phase homogenous liquid-liquid extraction method followed by deep eutectic solvent-based dispersive liquid-liquid microextraction has been used for the extraction and preconcentration of some phytosterols from cow milk and cream samples. In this method, cow milk or melted cream was transferred into a glass test tube and a mixture of sodium hydroxide solution (as fatty acids saponification agent) and acetonitrile (as extraction/dispersive solvent) was added to the solution. The mixture was shaken manually and placed in a water bath. After dissolving sodium chloride and centrifugation, the obtained supernatant phase (acetonitrile) was removed and mixed with ethyl methyl ammonium chloride: phenyl acetic acid deep eutectic solvent at microliter level. Under optimum conditions, low limits of detection (1.6-4.1μg/L) and quantification (5.3-13.1μg/L), high enrichment factors (138-207), and extraction recoveries (55-83%), and good precision (relative standard deviations ≤ 6.8%) can be obtained. The method was done on different milk and cream samples and the results showed that total phytosterols level in all samples were in the permitted level established by the National Standard Organization Guidelines, except for three cream samples.

Preparation of multiwall carbon nanotube/urea-formaldehyde nanocomposite as a new sorbent in solid-phase extraction and its combination with deep eutectic solvent-based dispersive liquid-liquid microextraction for extraction of antibiotic residues in honey.

A solid-phase extraction method combined with deep eutectic solvent-based dispersive liquid-liquid microextraction has been developed for the extraction of three antibiotics in honey samples prior to their determination by ion mobility spectrometry. In this method, first, a multiwall carbon nanotube/urea-formaldehyde nanocomposite was synthesized using co-precipitation polymerization method and then it was used as a sorbent for the analytes extraction from the samples. After that the adsorbed analytes were eluted from the sorbent using a water-miscible organic solvent. The collected elution solvent was mixed with tetrabutylammonium chloride:butanol deep eutectic solvent and the mixture was applied in the following microextraction method. The method provided low limits of detection and quantification in the ranges of 0.32-0.86 and 1.1-2.9ng/g, respectively. The method had a proper repeatability expressed as relative standard deviation less than or equal to 9.1%. The validated method was successfully performed on different honey samples obtained from different producers.

A novel dispersive liquid-liquid microextraction using a low density deep eutectic solvent-gas chromatography tandem mass spectrometry for the determination of polycyclic aromatic hydrocarbons in soft drinks

Ready-to-drink teas can provide, if properly packaged, the taste and wellness character of traditional teas. Nevertheless, in tea processing, there may be several contaminations, among which polycyclic aromatic hydrocarbons (PAHs), anthropogenic contaminants that can present carcinogenic and mutagenic properties. In this work, a novel low-density deep eutectic solvent-based dispersive liquid-liquid microextraction (LDDES-DLLME) procedure followed by gas chromatography tandem mass spectrometry (GC-MS/MS) was optimized for analysis of 15 polycyclic aromatic hydrocarbons (PAHs) in ready-to-drink herbal-based beverages. The new deep eutectic solvent (DES) was synthesized with natural compounds (camphor and hexanoic acid). Several parameters of the extraction procedure such as type and volume of extraction solvent, type, volume of dispersive solvent, and time of extraction were evaluated to achieve the highest yield and to attain the lowest detection limits. The validated method showed very low limits of detection (0.01 μg L-1) and quantification (0.2 μg L-1), good inter- and intra-day precisions (RSD<16.87%), and recoveries higher than 69%. The method was applied to 16 type of samples and it was found total PAHs levels ranging from 0.20 to 1.82 μg L-1. The developed LDDES-DLLME showed a reliable and innovative alternative for the extraction of PAHs from beverages, cost-effective and environmentally friendly, and providing a satisfactory throughput.

A three-phase solvent extraction system combined with deep eutectic solvent-based dispersive liquid-liquid microextraction for extraction of some organochlorine pesticides in cocoa samples prior to gas chromatography with electron capture detection.

A sample pretreatment method based on the combination of a three-phase solvent extraction system and deep eutectic solvent-based dispersive liquid-liquid microextraction has been introduced for the extraction of four organochlorine pesticides in cocoa samples before their determination by gas chromatography-electron capture detection. A mixture of sodium chloride, acetonitrile, and potassium hydroxide solution is added to cocoa bean or powder. After vortexing and centrifugation of the mixture, the collected upper phase (acetonitrile) is removed and mixed with a few microliters of N,N-diethanol ammonium chloride: pivalic acid deep eutectic solvent. Then it is rapidly injected into deionized water and a cloudy solution is obtained. Under optimum conditions, the limits of detection and quantification were found to be 0.011-0.031 and 0.036-0.104ng/g, respectively. The obtained extraction recoveries varied between 74 and 92%. Also, intra- (n=6) and interday (n=4) precisions were less than or equal to 7.1% for the studied pesticides at a concentration of 0.3ng/g of each analyte. The suggested method was applied to determine the studied organochlorine pesticide residues in various cocoa powders and beans gathered from groceries in Tabriz city (Iran) and aldrin and dichlobenil were found in some of them.

Deep eutectic solvent-based dispersive liquid-liquid micro-extraction for extraction of malachite green and crystal violet in water samples prior their determination using high performance liquid chromatography

ABSTRACT A new dispersive liquid-liquid micro-extraction (DLLME) was developed to extract malachite green (MG) and crystal violet (CV) in water samples using a hydrophobic deep eutectic solvent (DES) before their determination by high performance liquid chromatography (HPLC). The hydrophobic DES was prepared by mixing benzyltriethylammonium chloride (BTEAC) as acceptor of hydrogen bond and thymol as donor of hydrogen bond at 70ºC for 10 min. Influencing factors on DLLME were considered and optimised. In optimal conditions, the limit of detection (LOD) for MG and CV was 0.03 and 0.05 µg L−1, respectively. Calibration curve for both dyes was linear in the range 0.2–500 µg L−1 with a correlation coefficient greater than 0.99. Also, pre-concentration factor for MG and CV was 95 and 100, respectively. The within-day and between-day precision at concentration levels of 10 and 100 µg L−1 were less than 7%. Finally, the applicability of the proposed method was evaluated through the analysis of water samples and the relative recoveries obtained (90.0–97.5%) were acceptable.