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).

Ultrasound-Assisted Extraction Combined with Low-Density Solvent-Based Dispersive Liquid-Liquid Microextraction as an Efficient and Sensitive Method for the Determination of Clodinafop-Propargyl Herbicide in Wheat Samples

Ultrasound-Assisted Extraction Combined with Low-Density Solvent-Based Dispersive Liquid-Liquid Microextraction as an Efficient and Sensitive Method for the Determination of Clodinafop-Propargyl Herbicide in Wheat 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.

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.

Dispersive liquid-liquid microextraction based on a supramolecular solvent followed by high-performance liquid chromatographic analysis of lignans in Forsythiae Fructus.

A supramolecular solvent-based dispersive liquid-liquid microextraction was proposed for the extraction and determination of lignans in Forsythiae Fructus combined with high-performance liquid chromatography. The supramolecular solvent, consisting of tetrabutylammonium bromide and n-hexanol, was mixed with the sample solution to extract the analytes by a vortex. After accomplishing the extraction, the extraction phase was separated by centrifugation and collected for high-performance liquid chromatography analysis. In this work, the important extraction variables such as the type and amount of extraction solvent, pH and salt amount in the sample phase, and extraction time were optimized. The synthesis of supramolecular solvent was studied and its microstructure was characterized by transmission electron microscopy. Under the optimal conditions, the analytes' enrichment factors were between 6 and 170 for the proposed procedure. Satisfactory linear ranges (r ≥ 0.99), detection limits (0.025-0.4ng/ml), precisions (<9.2%), and accuracies (recoveries: 96.5%-104.8%) were obtained. The method has been successfully applied to the preconcentration of lignans in Forsythiae Fructus with simple and rapid operation, low cost, and environmental friendliness.

Effervescent powder-assisted floating organic solvent-based dispersive liquid-liquid microextraction for determination of organochlorine pesticides in water by GC–MS

An effervescent powder-assisted floating organic solvent-based dispersive liquid-liquid microextraction was introduced for determination of 13 organochlorine pesticides in water samples. In this method, a less toxic low-density organic solvent was used as extraction solvent. The extraction solvent was dispersed in to the aqueous sample via CO2 bubbles, in-situ generated up on addition of water to a falcon tube containing the mixture of effervescent powder precursors as well as the extraction solvent. Various experimental parameters such as effervescent and its weight fractions, extraction solvent type and its volume, the total mass of effervescent precursors, and the effect of salt were investigated and the optimal conditions were established. Under the optimum conditions, the proposed method exhibited good linearity for all target pesticides with the coefficient of determinations varying from 0.9981 to 0.9997. The limits of detection and quantification were within the range of 0.03–0.24 and 0.26–0.75 μg/L, respectively. The intra- and inter-day precisions which were expressed in terms of the relative standard deviation ranged from 0.33 to 4.47 and 0.51–5.52%, respectively. The enrichment factors and recoveries ranged from 24 to 293 and 76–116%, respectively. The proposed method could be used simple, cheap, fast, and environmentally friendly alternative for analysis of organochlorine pesticides from environmental water and other similar matrices.

Deep Eutectic Solvent Based Dispersive Liquid-liquid Microextraction for the Determination of Azo Dyes in Beverages

Deep Eutectic Solvent Based Dispersive Liquid-liquid Microextraction for the Determination of Azo Dyes in Beverages

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.

Bio-derived solvent-based dispersive liquid-liquid microextraction followed by smartphone digital image colorimetry for the detection of carbofuran in cereals

Bio-derived solvent-based dispersive liquid-liquid microextraction coupled with smartphone digital image colorimetry (BDS-DLLME with SDIC) was established to detect carbofuran in cereals. Carbofuran was hydrolyzed to benzofuranol by adding Na2CO3 solution. Bio-derived solvent p-cymene as the extractant and acetic acid as the dispersant were utilized in the DLLME process. The Na2CO3 and acetic acid reacted to generate CO2 bubbles, increasing the contact area between the extractant and sample solution. Thus, the rapid and efficient extraction of benzofuranol was achieved. Fe3O4 nanoparticles catalyzed the oxidative coupling reaction between benzofuranol and 4-aminoantipyrine in the presence of H2O2. Thus, the colorless solution was changed to purple-red which was captured using a smartphone and analyzed with an RGB system, achieving the quantitative detection of carbofuran. The concentration of carbofuran had a good linear relationship in the range of 0.02–20 mg kg−1. The limit of quantification was 0.018 mg kg−1, and the limit of detection was 0.005 mg kg−1. This method was successfully applied to analyze cereal samples with the recoveries of 91.1–113.8%. The BDS-DLLME with SDIC method was used to detect carbofuran with good sensitivity, selectivity, and reliability. The developed method has broad application prospects in rapid and efficient extraction and detection.

Combination of headspace solid phase extraction with lighter than water organic solvent-based dispersive liquid-liquid microextraction for the extraction of residual solvents from herbal laxative medicine prior to gas chromatography-flame ionization detection

Combination of headspace solid phase extraction with lighter than water organic solvent-based dispersive liquid-liquid microextraction for the extraction of residual solvents from herbal laxative medicine prior to gas chromatography-flame ionization detection

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.

Front Cover: Switchable hydrophilic solvent‐based dispersive liquid‐liquid microextraction coupled with high‐performance liquid chromatography for the determination of four types of sulfonylurea herbicides in soils

DOI: 10.1002/jssc.202100703 The cover picture shows a novel method for the determination of four types of sulfonylurea herbicides in soils by switchable hydrophilic solvent-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography. Switchable hydrophilic solvent became an excellent extractant in sulfonylurea herbicide analysis due to the unique connection between the switchable hydrophilic solvent and the sulfonylurea herbicides. Therefore, the proposed method was proved to be green, more benign to the environment and easy to operate and had a potential to be applied to other complex 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.

Switchable hydrophilic solvent-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the determination of four types of sulfonylurea herbicides in soils.

In this study, switchable hydrophilic solvent-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography was developed for the determination of four sulfonylurea herbicides in soils. For the first time, the sample pretreatment was achieved due to the similar acid-base status of sulfonylurea herbicides and switchable hydrophilic solvent. In the extraction step, sulfonylurea herbicides were extracted as anions and transferred to an alkaline solution with switchable hydrophilic solvent anions. In the concentration step, two types of anions were transformed to their molecular state after the aqueous solution was acidified. In addition, the dispersion and microextraction processes were completed efficiently with the simultaneous formation of analytes and extractants. The factors affecting the extraction performance were optimized. Under the optimized conditions, good linearity was observed for each herbicide with correlation coefficients ranging from 0.9952 to 0.9978. The limits of detection were in the range of 0.1-0.2 μg/g. Moreover, the relative recoveries of the sulfonylurea herbicides at spiking levels of 0.5, 1, and 1.5 μg/g in soil samples were between 75 and 111% (relative standard deviations: 0.4-11.4%). Therefore, the proposed method in this study could be successfully applied to the analysis of four types of sulfonylurea herbicides in soil samples.

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.

Effervescent tablet-assisted switchable hydrophilicity solvent-based on-site dispersive liquid-liquid microextraction coupled with gas chromatography for the determination of pyrethroid pesticides in environmental waters

A novel effervescent tablet-assisted switchable hydrophilicity solvent-based on-site dispersive liquid-liquid microextraction coupled with gas chromatography detection has been developed to determine five pyrethroid insecticides in environmental water samples. In this method, effervescent tablets contain effervescent precursors and extractants, which play a dual role of dispersion and extraction. After effervescence reaction, the formation of extractant and the extraction of analytes were accomplished simultaneously. Phase separation were carried by filtration using homemade filter column, which of filter is oil-absorbing cotton polypropylene. After phase separation, the extractant phase were obtained by elution. No electric instrument was required in sample pre-treatment step in the developed method. Experimental conditions affecting the extraction efficiencies have been optimized, such as type and amount of extractant, type of effervescent tablets, etc. Under the optimized conditions, the linearity was 5-500μg L-1, with coefficients greater than 0.9990. The limit of detection and the limit of quantitation were in the range of 0.22-1.88μg L-1 and 0.75-6.25μg L-1. The relative standard deviations ranged from 0.8% to 6.1%. The enrichment factors were in the range of 65-108. This method was successfully applied to the on-site processing of tap, reservoir and river water.

Supramolecular solvent-based microextraction for the preconcentration of Pb2+ and Cd2+ prior to spectrophotometric detection.

Supramolecular solvent-based dispersive liquid-liquid microextraction technique has been developed as a preconcentration tool for the determination of trace level of Pb2+ and Cd2+. Dodecanol dispersed in tetrahydrofuran has been utilized as a supramolecular-solvent system for the extraction of analytes prior to their quantitative determination with graphite furnace atomic absorption spectrophotometer. Both Pb2+ and Cd2+, which were efficiently extracted by supramolecular solvent system, were complexed with dithizone followed by the addition of supramolecular solvent. The experimental variables that could possibly influence the extraction efficiency, i.e. pH value, temperature, sample volume, centrifugation time, rate of centrifugation, ionic strength, etc. were subjected to the optimization step. An interference study was also conducted to check the selectivity of developed method. Limit of detection calculated for Pb2+ and Cd2+ was 0.015 and 0.061 mg L-1, respectively. The limit of quantification was 0.05 and 0.2 mg L-1 for Pb2+ and Cd2+, respectively. The analytical signal was enhanced to 30 times in case of Pb2+ and 27 times in case of Cd2+. The results obtained revealed that the developed method is rapid, simple, sensitive, and efficient for the determination of both analytes in real water samples.