Deep Eutectic Solvent-based Microextraction Research Articles

Spectrophotometric determination for green hydrophobic deep eutectic solvent-based microextraction of Brilliant Blue FCF (E133) from beverages

In this study, a simple, sensitive, and rapid method called green hydrophobic deep eutectic solvent-based liquid-liquid microextraction was developed to extract Brilliant Blue FCF dye from beverages. This method utilizes hydrophobic DES obtained by forming tetrabutylammonium bromide and 1-octanol in a 1:5 ratio as green extraction solvent. The transition of Brilliant Blue FCF to the DES phase occurred on its own, without the need for any reagents such as added salt or tetrahydrofuran. Several crucial factors were tried to get the best extraction efficiency, including species, DES volume and molar ratio, solution pH, ultrasonication, and centrifugation time. Under optimum conditions, extraction recoveries were achieved in the range of 95.1–101.3 % with the method developed for Brilliant Blue FCF. The detection and determination limits were observed to be 4.1 μg l-1 and 12.1 μg l-1, respectively. In addition, the relative standard deviation values for the method's accuracy were found to be 2.23 % and 3.48 % within and between days, respectively. It has been established that the developed method is highly environmentally friendly thanks to the application of the Analytical GREENness (AGREE) and Green Analytical Procedure Index (GAPI) tools. This study shows that DES applications can be carried out without the use of emulsifiers and dispersants by prioritizing the use of hydrophobic DES compounds as environmentally friendly and green extraction solvents in food samples.

Exploration of deep eutectic solvent-based microextraction for quercetin monitoring in plant samples

This study delves into utilizing a microextraction process based on deep eutectic solvents (DES) for determining quercetin (QUR) levels in plant samples. The preparation of the DES involves a choline chloride (CC) to 1, 2-propanediol (PR) in a 1:4 ratio for efficient quercetin extraction. Through multivariate procedures, critical microextraction variables such as extraction time, pH, solvent volume, salinity, and sodium chloride were optimized to enhance quercetin extraction efficiency. Using the proposed procedure, the best response was found with a DES volume of 149 µL, extraction time of 4 min, pH 3.3, and salinity 2.9 % W/V sodium chloride with Desirability = 1. The method exhibited a detection limit of 9.8 ng mL−1 and an enrichment factor of 61-fold for quercetin. The working range for detection was determined to be 30–5000 ng mL−1. These findings highlight the efficacy of the developed microextraction method for accurately determining quercetin levels in plant samples with favorable recoveries in the range of 99.15 % −101.27 %.

Temperature-responsive deep eutectic solvent-based microextraction for the determination of bisphenols in beverages by HPLC-FLD

In this work, a homogeneous liquid-liquid microextraction approach based on temperature-responsive deep eutectic solvent for pretreatment of beverages was developed for the first time. The procedure assumed the heating of the homogeneous solution, consisting of sample, precursors of temperature-responsive deep eutectic solvent (amphiphilic amine and carboxylic acid) and salting-out agent in a disposable polyethylene pipette. The heating of extraction system induced the change of acid-base properties of the precursors, and thus it attributed to in situ formation of microdroplets of deep eutectic solvent in beverage sample. The significant difference in densities of aqueous sample phase and the extraction solvent allowed to obtain spontaneous phase separation, while the presence of a thin capillary on top of the pipette facilitated microvolume sampling of the resulting extract. The approach was utilized for the determination of bisphenols (bisphenol A, bisphenol C, bisphenol E and bisphenol F) in beverages by high-performance liquid chromatography with fluorometric detection. The temperature-responsive deep eutectic solvent based on lidocaine and heptanoic acid provided the highest preconcentration of analytes (enrichment factor – 22). Under optimal conditions, the RSD in terms of inter-day precision was < 11 %, limits of detection for bisphenols were 0.01–0.03 μg L−1.

A hydrophobic deep eutectic solvent-based microextraction for the determination of ultra-trace arsenic in foods by an electrothermal atomization atomic absorption spectrometry

A hydrophobic deep eutectic solvent-based liquid-phase microextraction approach for the determination of ultra-trace arsenic (total) in foods by an electrothermal atomization atomic absorption spectrometry was developed. Various deep eutectic solvents based on tetraoctylammonium bromide and fatty acids (heptanoic, octanoic, nonanoic, decanoic acids) were studied as extraction solvents for preconcentration of arsenic (V) from mineralizates obtained after a microwave digestion of food samples. Phenomenon of ion-pairs formation between dihydroarsenate and precursor of deep eutectic solvent (tetraoctylammonium) and mass-transfer of the ion-pairs into deep eutectic solvent phase was presented for the first time. The proposed approach allowed to preconcentrate analyte into the deep eutectic solvent phase without the use of additional organic solvents (emulsifier agents or dispersive solvent), chelating and reducing agents. It was found, that the deep eutectic solvent based on tetraoctylammonium bromide and heptanoic acid provided more effective preconcentration of analyte from mineralizates (95% extraction recovery, 57-fold enrichment factor). The obtained limit of detection, calculated as a triple signal-to-noise ratio, was 10 ng L−1. The microextraction procedure was applied for the determination of trace arsenic in rice and wheat grains samples.

Three-component deep eutectic solvent-based microextraction approach for biodiesel quality control: Determination of water and metals

Biodiesel is an important alternative fuel produced by blending biofuels with petroleum diesel. Biofuel production is usually carried out by catalytic interesterification of animal fats or vegetable oils, followed by the removal of by-products and catalysts through washing with water. Residual amounts of water and catalysts can accelerate fuel biodegradation and contribute to the corrosion of metal surfaces. Considering the need to control the quality of biodiesel fuel, a simple and environmentally friendly analytical approach was first developed for the determination of water and metals (sodium, potassium, magnesium, calcium as catalysts, and iron, copper, tin, zinc, lead as feedstock elements) using a deep eutectic solvent. The technique involved microextraction of analytes from biodiesel into a new three-component deep eutectic solvent (choline chloride, lactic acid, and cobalt chloride) using a laboratory vortex, followed by impregnating the filter paper with the obtained extract to determine the analytes. The colorimetric determination of water is based on a change in the color of the deep eutectic solvent, which goes from blue to pink due to the formation of cobalt aqua complexes. The detection of water on the filter paper was carried out using a conventional scanner. The content of metals on the filter paper was determined by X-ray fluorescence spectrometry. Under optimal conditions, the detection limit was 100 mg kg−1 for water and 0.03–3 mg kg−1 for metals. The technique enabled multicomponent analysis to be carried out without the use of dangerous Karl Fischer reagents (for water determination) and microwave mineralization of samples (for elemental analysis). The enrichment factor ranged from 290 to 330, and the RSD was less than 15%.

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.

Natural deep eutectic solvent-based microextraction for mercury speciation in water samples

A new natural deep eutectic solvent (NADES)-based analytical method for mercury speciation in water samples is presented. A NADES (i.e., decanoic acid:DL-menthol in a molar ratio of 1:2) is used as an environmentally friendly extractant for separation and preconcentration using dispersive liquid–liquid microextraction before LC-UV–Vis. Under optimal extraction conditions (i.e., NADES volume, 50 µL; sample pH, 12; volume of the complexing agent, 100 µL; extraction time, 3 min; centrifugation speed, 3000 rpm; and centrifugation time, 3 min), the limit of detection values were 0.9 µg L−1 for the organomercurial species and 3 µg L−1 for Hg2+, which had a slightly higher value. The relative standard deviation (RSD, n = 6) has been evaluated at two concentration levels (25 and 50 µg L−1) obtaining values for all the mercury complexes within the range of 6–12% and 8–12%, respectively. The trueness of the methodology has been evaluated using five real water samples from four different sources (i.e., tap, river, lake, and wastewater). The recovery tests have been performed in triplicate obtaining relative recoveries between 75 and 118%, with RSD (n = 3) between 1 and 19%, for all the mercury complexes in surface water samples. However, wastewater sample showed a significant matrix effect (recoveries ranged between 45 and 110%), probably due to the high amount of organic matter. Finally, the greenness of the method has also been evaluated by the analytical greenness metric for sample preparation (i.e., AGREEprep).Graphical

Deep eutectic solvents with low viscosity for automation of liquid-phase microextraction based on lab-in-syringe system: Separation of Sudan dyes

In the work limitations of deep eutectic solvents in the flow-based analysis are discussed. Deep eutectic solvents based on terpenes and fatty acids with low viscosity were studied as extraction solvents for liquid-liquid microextraction into a lab-in-syringe system for the first time. As a result an automated deep eutectic solvent-based microextraction approach was proposed. The procedure involved aspiration of deep eutectic solvent (based on terpene and fatty acid) and aqueous sample solution followed by phases mixing by a magnetic stirrer inside a syringe of flow system. After phase separation the extract phase was transferred from the syringe into a vial followed by analysis by a high-performance liquid chromatography with diode-array detection. The determination of Sudan I, Sudan II and Sudan III in chili-based sauces was considered as an analytical task. The mass-transfer intensification performed by the magnetic stirring inside the syringe allowed to perform fast (2 min) and efficient (extraction recoveries 87–95%) extraction. The limits of detection, calculated from a blank test based on 3σ, were from 0.003 to 0.005 mg kg−1, RSD was <9%. The microextraction procedure did not involve the use of hazardous organic solvents, only 100 μL of natural deep eutectic solvent was required for dyes preconcentration.

A deep eutectic solvent-based microextraction procedure for simple and fast extraction of doxorubicin as an anticancer drug from urine samples followed by 96-well microplates-based spectrophotometric detection

A deep eutectic solvent-based microextraction procedure for simple and fast extraction of doxorubicin as an anticancer drug from urine samples followed by 96-well microplates-based spectrophotometric detection

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.

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

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

Deep Eutectic Solvent-Based Microextraction of Lead(II) Traces from Water and Aqueous Extracts before FAAS Measurements.

Microextraction procedures for the separation of Pb(II) from water and food samples extracts were developed. A deep eutectic solvent composed of α-benzoin oxime and iron(III) chloride dissolved in phenol was applied as a phase separator support. In addition, this deep eutectic mixture worked as an efficient extractor of Pb(II). The developed microextraction process showed a high ability to tolerate the common coexisting ions in the real samples. The optimum conditions for quantitative recoveries of Pb(II) from aqueous extracts were at pH 2.0, conducted by adding 150 µL from the deep eutectic solvent. The quantitative recoveries were obtained with various initial sample volumes up to 30 mL. Limits of detection and limits of quantification of 0.008 and 0.025 µg L−1 were achieved with a relative standard deviation (RSD%) of 2.9, which indicates the accuracy and sensitivity of the developed procedure. Recoveries from the reference materials, including TMDA 64.2, TMDA 53.3, and NCSDC-73349, were 100%, 97%, and 102%, respectively. Real samples, such as tap, lake, and river water, as well as food samples, including salted peanuts, chickpeas, roasted yellow corn, pistachios, and almonds, were successfully applied for Pb(II) analysis by atomic absorption spectroscopy (AAS) after applying the developed deep eutectic solvent-based microextraction procedures.

A novel-easy deep eutectic solvent-based microextraction procedure for the separation, preconcentration and spectrophotometric determination of chromotrope 2R in water, detergent and food samples

ABSTRACT An efficient and simple deep eutectic solvent (DES)-based liquid phase microextraction method has been used for chromotrope 2R dyestuff at trace levels prior to its UV-Vis spectropthometric determination. In this aspect, DES was prepared by decanoic acid and tetra-n-butylammonium bromide component used as 1:3 molar ratios. The developed separation-preconcentration method was optimised various analytical parameters such as pH, sample volume, eluent sample volume, volume of DES, sample volume of tetrahydrofuran (THF) and matrix effect etc. on the recovery of chromotrope 2R dyestuff were investigated. Quantitative recovery data for chromotrope 2R were found at pH 3.0. The detection limits of the chromotrope 2R were found to be as 5.4 µg L−1. The accuracy of the developed method was successfully applied by the determination of the addition-recovery studies in the water sample, detergent and food samples with satisfactory results. The proposed method was applied to natural water samples for the determination of chromotrope 2R with satisfactory results.

Spectrophotometric determination of traces allura red in environmental samples after a deep eutectic solvent-based microextraction

ABSTRACT A new method has been developed based on UV–Vis spectrophotometer measurement after liquid-phase microextraction using deep eutectic solvents for the determination of allura red dye. Tetra-n-butyl ammonium bromide and decanoic acid were used as deep eutectic solvent components by the developed method. The effects of the method on recovery, mainly pH, deep eutectic solvent components and volume, tetrahydrofuran volume, matrix effects, model solution volume, ultrasonication time and centrifugation time were also investigated. Allura red was extracted into the deep eutectic solvent phase at pH 4.0. The relative standard deviations were lower than 5%. The limit of detection (LOD) and preconcentration factor were found to be 3.92 µg/L and 13, respectively. The accuracy of the method was confirmed by the addition method on water, detergent and chocolate samples.

Acid-base-governed deep eutectic solvent-based microextraction combined with magnetic solid-phase extraction for determination of phenolic compounds.

A sensitive method based on the use ofgreen deep eutectic solvents (DESs) was designed for the determination of bisphenol-A, bisphenol-AF, tetrabromobisphenol-A and 4-tert.-octylphenol followed by HPLC. This method takes advantage of magnetic solid-phase extraction purification and acid-base induced DES liquid-liquid microextraction. The Mg(II)-Al(III) layered double hydroxide-coated magnetic nanoparticles were selected to purify samples. The DESs were systematically prepared by a range of medium-chain saturated fatty acids (C8-C12) and D,L-menthol. The melting point and the extraction efficiency of phenolic compounds were adjusted by changing the carbon chain length of fatty acid in suitable proportions. Acid-base induction significantly improves the extraction efficiency. The method has lower limits of detection ranging from 6 to 11ngL-1, good linearity (0.05-500μgL-1) and high enrichment factors (86-91). The method was successfully applied for the determination of four phenolic compounds in beverage samples. The recoveries ranged from 84.4 to 101.3%. Graphical abstract Schematic representation of the extraction of four phenolic compounds by medium chain (C8-C12) fatty acid-based eutectic solvent (DES) through acid-base-induction.

Development of a chemometric-assisted deep eutectic solvent-based microextraction procedure for extraction of caffeine in foods and beverages

ABSTRACT In this research article, a novel and green deep eutectic solvent-based microextraction (DES-ME) procedure based on chemometric-assisted (CA) optimization was developed for the extraction of caffeine in foods and beverages prior to its spectrophotometric determination. Ultrasound was used to accelerate the extraction of caffeine. Deep eutectic solvents (DES), prepared in an ultrasonic bath at 20–60 min for 60–80°C, were used as extraction solvents. The important experimental variables (pH, DES amount, temperature, sonication time and metal concentration) were modelled and optimized using response surface methodology (RSM) based on central composite design (CCD). Under the optimum conditions, the proposed method allowed the determination of caffeine with limits of detection (LOD, 3sblank/m) and quantification (LOQ, 3sblank/m) of 7.5 and 25.0 µg L−1, respectively. For 40 µg L−1 and 100 µg L−1 of caffeine (n = 5), relative standard deviations (RSDs%) and recoveries% were 1.2–1.6% and 96.7–98.2%, respectively. Validation studies (accuracy, precision, trueness, reliability and selectivity) of the method were performed before the analysis of real samples. The results showed that the combination of the CCD with the DES-ME can be considered as a new perspective for the extraction and determination of caffeine in foods and beverages.

Natural deep eutectic solvent-based ultrasound-assisted-microextraction for extraction, pre-concentration and analysis of methylmercury and total mercury in fish and environmental waters by spectrophotometry

ABSTRACTIn this study, a simple, pH-controlled, and natural deep eutectic solvent-based microextraction (NADES-ME) procedure is proposed before the spectrophotometric analysis of methylmercury (MeHg) and total mercury in fish and environmental waters. The method is based on charge-transfer sensitive ion-pair formation between MeHg and 3-(dimethylamino)-7-(methylamino)phenothiazin-5-ium chloride (Azure B – AzB) in the presence of chelating citrate-phosphate buffer at pH 6.0, and then extraction of the formed ion-pair complex with the NADES. The important variables affecting extraction efficiency were evaluated and optimised. At optimal conditions (300 µL of 1.0 × 10−3 mol L−1 AzB, 600 µL NADES (betaine-sorbitol, 1:3) containing 10% water (v/v) as extractant, 375 µL acetonitrile as aprotic solvent for sonication of 7 min at power of 300 W/40 kHz, and centrifugation at 4000 rpm for 3 min, respectively), the figures of merit for MeHg include a good linearity in the concentration range of 0.7–340 µg L−1, limits of detection and quantification of 0.25 and 0.83 µg L−1, and pre-concentration and sensitivity enhancement factors of 120 and 95, respectively. Figures of merit for total Hg (iHg, where Hg22+ ions are predominantly present in natural oxygen-rich waters such as freshwaters and seawater as well as elemental Hg and Hg2+ ions at very low amounts) after pre-oxidation at pH 5.0 include linearity range of 3–270 µg L−1 with limits of detection and quantification of 0.92 and 3.10 µg L−1, and pre-concentration and sensitivity enhancement factors of 120 and 35, respectively. The reliability (with recovery of 92–98.7% and RSD of 1.9–5.5%) was statistically validated by analysis of two standard reference materials (SRMs) with and without spiking. The method was successfully applied to the speciation analysis of total Hg, iHg and MeHg in fish and environmental waters.