Deep Eutectic Solvent-based Liquid-phase Microextraction Research Articles

Deep eutectic solvent based on thymol and menthol for microextraction and sensitive UV-Vis determination of total selenium in eggs and chicken tissue

A hydrophobic deep eutectic solvent-based liquid-phase microextraction combined with UV-Vis spectrophotometry was presented for the determination of selenium in eggs and chicken tissue for the first time. Selenium is commonly used in the poultry industry as an additive in broiler feed and its determination in chicken products is important analytical task. In this study, deep eutectic solvents based on terpenoids (thymol and menthol) and fatty acids were investigated as extraction solvents for the sensitive determination of trace selenium amounts by UV-Vis spectrophotometry. The procedure involved microwave digestion of food sample, formation of yellow compound of piazselenol in the presence of selenium (IV) and 3,3′-diaminobenzidine followed by piazselenol microextraction. The quantification of selenium in deep eutectic solvent phase was carried out in a flow cell of a portable UV-Vis spectrometer. The sensitivity was improved by about 300 folds when compared with the UV-Vis spectrophotometry without analyte preconcentration. Deep eutectic solvent based on thymol and menthol provided suitable conditions for analyte detection. The analytical parameters for the quantitative microextraction of analyte were investigated and optimized. Validation of the procedure was performed. The linearity range was 7–150 µg kg−1 (0.14–3 µg L−1) and the limit of detection and limit of quantification were 2 µg kg−1 (0.04 µg L−1) and 7 µg kg−1 (0.14 µg L−1). The proposed procedure was successfully applied to analysis of real eggs and chicken tissue samples. The procedure does not require sophisticated and expensive analytical instrumentation and can be found application in food quality control laboratories.

Simultaneous complexation and extraction of manganese in melissa tea sample by deep eutectic solvent based liquid phase microextraction

Manganese at trace levels cannot be detected by flame atomic absorption spectrophotometer (FAAS) without a preconcentration method. In the presented study, an accurate and sensitive analytical method for the determination of manganese at trace levels in melissa tea samples was established. Deep eutectic solvent based liquid phase microextraction (DES-LPME) was used to preconcentrate the analyte from aqueous medium. Several important parameters were individually optimized to achieve high signal to noise ratio for the analyte in FAAS system. Under the optimum experimental conditions, limit of detection (LOD), limit of quantitation (LOQ) and linear range (LR) for the developed DES-LPME-FAAS system were found as 1.7 µg/kg, 5.8 µg/kg and 6.5–202.8 µg/kg, respectively. Enhancement in detection power was calculated as 112.2 folds by dividing manganese LOD value in FAAS system to value obtained by DES-LPME-FAAS system. Three different melissa tea samples were analyzed by the proposed method to find their manganese content. Percent recovery results for the tea samples ranged between 80.4% and 122.6% with low standard deviation values.

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.

An eco-friendly and sensitive deep eutectic solvent-based liquid-phase microextraction procedure for extraction preconcentration of Pb (II) ions.

In recent years, interest in green solvents, which are environmentally friendly, easy to prepare and biodegradable, and in their applications in chemistry has considerably increased. In the current study, a new and easy deep eutectic solvent-based liquid-phase microextraction method compatible with green chemistry principles was developed for preconcentration of Pb (II) ions. The amount of Pb (II) ions was determined with graphite furnace atomic absorption spectrometry (GFAAS). Various analytical parameters such as deep eutectic solvent (DES) ratio and amount, ligand amount, pH, sample volume were optimized and the effects of potential matrix ions on the method were investigated. The preconcentration factor of the method was found to be 160, while the limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.071µg L-1 and 0.236µg L-1, respectively. The developed procedure was performed to determine Pb (II) ions in lake and river waters, and the accuracy of the procedure was determined with certified reference wastewater (SPS-WW1) analysis.

Development and Factorial Experimental Design Optimization of Deep Eutectic Solvent‐Based Microextraction of Carmoisine (E122) in Candy and Water Samples

A new deep eutectic solvent-based liquid phase microextraction (DES-LPME) method was developed and used to separate and enrich Carmoisine (E122). The deep eutectic solvent containing tetrabutylammonium bromide (TBABr) and decanoic acid (DA) was prepared and employed with multivariate statistical design for the optimization of the spectrophotometric analysis conditions to determine carmoisine in the extractant phase. The optimized limit of detection (LOD), limit of quantification (LOQ), and preconcentration factor were 3.3 µg L−1, 11.1 µg L−1, and 10, respectively. The advantages of this approach are low solvent consumption and rapid analysis. The method analyzed candy and water samples with recoveries from 94% to 108%.

An eco-friendly ultrasound-assisted deep eutectic solvent-based liquid–phase microextraction method for enrichment and quantification of nickel in environmental samples

An eco-friendly and easy ultrasound-assisted liquid phase microextraction approach using deep eutectic solvent (UA-DES-LPME) was established to preconcentrate and separate trace amount of nickel (Ni(II)) in various environmental samples before flame atomic absorption spectrometric estimation. In this method, Ni(II) was complexed with 2-(benzothiazolyl azo) orcinol reagent. The impacts various parameters on the microextarction of Ni(II) was investigated. The calibration graph is linear in the range of 1–500 µg L−1 and limits of detection and quantification were determined as 0.27 and 0.90 μg L−1, respectively. The RSD% and preconcentration factor were 2.30% and 100, respectively. The analysis of certified reference materials demonstrated the validity of the established procedure. The microextraction method provided here simple, rapid, cheap, green and was effectively used to determine nickel levels in a variety of environmental samples with recoveries ranged of 95.0–98.54%.

Preconcentration of liposoluble constituents in Salvia Miltiorrhiza using acid-assisted liquid phase microextraction based on a switchable deep eutectic solvent

A switchable deep eutectic solvent-based liquid-phase microextraction was proposed and applied to the preconcentration and determination of liposoluble quality-markers of diterpenoid quinones (dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone IIA) in traditional Chinese medicine coupled with high performance liquid chromatography-ultraviolet detection. In the procedure, the hydrophilic deep eutectic solvent of diethanolamine-hexanoic acid (molar ratio 1:1) was prepared and added into the sample phase as an extractant, and a homogeneous solution was formed under slight vortex stirring. After the addition of HCl solution, the deep eutectic solvent miscible with the sample phase was converted to hydrophobic form, and a cloudy solution was generated. Then, the upper hydrophobic layer enriching the target analytes was collected through centrifugation for high performance liquid chromatography analysis. Several critical parameters affecting the extraction performance including the composition and consumption of switchable deep eutectic solvent, the type and amount of acid, salt amount and extraction time were investigated and optimized. Moreover, the structures of the deep eutectic solvent and the recovered hydrophobic layer were both characterized using Fourier transform infrared spectroscopy, further demonstrating the switching mechanism of the extractant during the extraction process. Under the optimal conditions, enrichment factors of diterpenoid quinones ranged from 59 to 274. Good linearities (r≥0.9963), low detection limits (0.5–0.7 ng/mL), satisfactory precisions (relative standard deviations 0.5%-8.6%) and accuracies (recoveries 94.6%-104.6%) were also obtained. Comparing the proposed switchable deep eutectic solvent-based liquid-phase microextraction with other published methods, the characteristics of the procedure were summarized. The developed method was successfully applied for the preconcentration of four liposoluble diterpenoid quinones from a traditional Chinese herbal medicine of Salvia Miltiorrhiza.

Novel deep eutectic solvent-based liquid phase microextraction for the extraction of estrogenic compounds from environmental samples.

Steroid hormones, such as estrone (E1), 17β-estradiol (E2), 17β-ethinylestradiol (EE2) and estriol (E3) are a group of lipophilic active substances, synthesized biologically from cholesterol or chemically. A pH-switchable hydrophobic deep eutectic solvent-based liquid phase microextraction (DES-LPME) technique was established and combined with gas chromatography-mass spectroscopy for the determination of estrogenic compounds in environmental water and wastewater samples. A DES was synthesized using l-menthol as HBA and (1S)-(+)-camphor-10-sulfonic acid (CSA) as HBD, and used as a green extraction solvent. By adjusting the pH of the solution, the unique behavior of the DES in the phase transition and extraction of the desired analytes was investigated. The homogenization process of the mixture is done only by manual shaking in less than 30 seconds and the phase separation is done only by changing the pH and without centrifugation. Some effective parameters on the extraction and derivatization, such as molar ratio of DES components, DES volume, KOH concentration, HCl volume, salt addition, extraction and derivatization time and derivatization prior or after extraction were studied and optimized. Under the optimum conditions, relative standard deviation (RSD) values for intra-day and inter-day of the method based on 7 replicate measurements of 20 ng L−1 of estrogenic compounds and 10 ng L−1 for internal standard in different samples were in the range of 2.2–4.6% and 3.9–5.7%, respectively. The calibration graphs were linear in the range of 0.5–100 ng L−1 and the limits of detection (LODs) were in the range of 0.2–1.0 ng L−1. The relative recoveries of environmental water and wastewater samples which have been spiked with different levels of target compounds were 91.0–108.8%.

Deep eutectic solvent-based liquid-phase microextraction coupled with reversed-phase high-performance liquid chromatography for determination of α-, β-, γ-, and δ-tocopherol in edible oils.

For simultaneous analysis of four fat-soluble tocopherols (α-, β-, γ-, and δ-) in edible oils, an efficient and green method using deep eutectic solvent-based liquid-phase microextraction (DES-LPME) coupled with reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The DESs formed by different quaternary ammonium salts and ethanol were used as the extractants. Tetrabutylammonium chloride (TBAC)-ethanol DES at a molar ratio of 1:2 achieved the best extraction efficiency. Under the optimized conditions, the detection limits were in the range of 2.1-3.0ngmL-1. The intra-day and inter-day repeatability were in the ranges of 3.9-5.3% and 4.8-7.1%, respectively, and the recoveries for the real samples varied from 80.7% to 105.4%. The developed method was successfully employed for the determination of all four tocopherol homologues with an RP-HPLC system containing a COSMOSIL π-NAP column in five edible oils collected locally. Graphical abstract.

Multivariate Optimization of an Ultrasound-Assisted Deep Eutectic Solvent-Based Liquid-Phase Microextraction Method for HPLC–UV Analysis of Carbamazepine in Plasma

An ultrasound-assisted deep eutectic solvent-based liquid-phase microextraction (UA-DES-LPME) was established, for the first time, for the extraction of carbamazepine (CBZ) from human plasma samples. The extract was determined by HPLC-ultraviolet detection (HPLC–UV). A deep eutectic solvent (DES) was readily synthesized by mixing choline chloride and phenol (ChCl:Ph) in the mole ratio of 1:2 in ambient temperature and used without any further purification. In the present method, THF was used as an emulsifier agent. Some parameters, including the DES components mole ratio, kind of emulsifier agent, and salt addition effect, were optimized by a one-at-a-time approach. Central composite design (CCD) was used to optimize the rest of the effective parameters, including DES volume, pH, ultrasonication time, and THF volume. The optimum conditions were found to be: 11.78 pH, 314 µL DES volume, 523 µL THF volume, and 9.0 min ultrasonication time. The performance of the method was evaluated under optimum conditions, and the method exhibited good linearity over a concentration range of 10–1500 ng mL−1, low limit of detection and quantitation, good precision, and high extraction recovery. Finally, the applicability of the method was assessed by analysis of the spiked plasma samples, and the results have shown high relative recoveries with good precision.

Efficacious and environmentally friendly deep eutectic solvent-based liquid-phase microextraction for speciation of Cr(III) and Cr(VI) ions in food and water samples

ABSTRACT A rapid, sensitive, and environmentally friendly air-assisted emulsification microextraction based on a deep eutectic solvent was developed for speciation of trace amounts of Cr6+ and Cr3+ ions in real samples. 1-(2-pyridylazo)-2-naphthol was used as a complexing agent and the decomposable and environmental friendly choline chloride-phenylethanol extraction solvent (ChCl:Ph-EtOH) was used as the extraction solvent. The resulting hydrophobic complex, i.e. Cr3+-1-(2-pyridylazo)-2-naphthol, was extracted into the extraction solvent by the air-assisted emulsification microextraction method, followed by its determination with flame atomic absorption spectrometry (FAAS). Different parameters affecting the extraction efficiency, including pH of the sample solution, ratio of the complexing agent to the analyte, number of extraction cycles and volume of the extraction solvent, were optimised using response surface methodology based on the central composite design (RSM-CCD). Under the optimum experimental conditions, the calibration curve was linear in the range of 1.0–300.0 ng mL−1 Cr3+ with a correlation coefficient of 0.997. The relative standard deviation (RSD) based on five replicate analyses of 200.0 ng mL−1 of Cr3+ ions was 4.7%, the limit of detection was 0.4 ng mL−1 (n = 5) and the preconcentration factor (PF) was 39. In order to check the applicability of the method, the chromium ions were determined in tap water and rice, as the model samples. Based on the results obtained, the proposed method was successfully used to determine the chromium species in different water and food samples.

A green, accurate and sensitive analytical method based on vortex assisted deep eutectic solvent-liquid phase microextraction for the determination of cobalt by slotted quartz tube flame atomic absorption spectrometry

Preconcentration of cobalt was carried out with deep eutectic solvent based liquid phase microextraction (DES-LPME) for trace determination by a slotted quartz tube (SQT) attached flame atomic absorption spectrometry (FAAS) system. Choline chloride and phenol in a 1:2 M ratio was used as a green solvent to extract cobalt from the aqueous sample solution. Key parameters influencing the extraction efficiency of cobalt were examined and optimized. Under the conditions optimized, the linear dynamic range was found between 5.0 and 50 µg L−1, and the limits of detection and quantification (LOD and LOQ) were calculated as 2.0 and 6.6 µg L−1, respectively. The detection power of the conventional FAAS was improved upon by 67 folds using the optimized DES-LPME-SQT-FAAS method. The developed analytical method was successfully applied for the determination of cobalt in linden tea samples and the recovery results obtained for different spiked concentrations (20, 30 and 40 µg L−1) were remarkable (≈100%).

Accurate and Precise Determination of Gold in Plating Bath Solution: Deep Eutectic Solvent Based Liquid Phase Microextraction – Slotted Quartz Tube – Flame Atomic Absorption Spectrometry

A sensitive, simple and green deep eutectic solvent based liquid phase microextraction (DES-LPME) method is described for the quantification of trace gold by flame atomic absorption spectrometry with a slotted quartz tube (SQT-FAAS). A 1:2 choline chloride:phenol mixture was utilized as the DES for the extraction of gold from the aqueous solution. All of the parameters affecting the extraction efficiency were optimized to increase the detection power of the FAAS. Under the optimum conditions, the presented method provided a linear range between 15 and 400 µg/L with limits of detection and quantification of 5.1 and 16.9 µg/L, respectively. An approximate 58-fold improvement was obtained in the detection power of the FAAS based on the limit of detection using the optimized DES-LPME-SQT-FAAS method. In order to check the validity/applicability of the method, recovery measurements were performed for spiked gold plating bath samples and the resulting recoveries were between 105.3% and 107.6%. The presented method was employed for real sample analysis.

Determination of lead in milk samples using vortex assisted deep eutectic solvent based liquid phase microextraction-slotted quartz tube-flame atomic absorption spectrometry system

Determination of lead at trace levels was achieved by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS) after the preconcentration with deep eutectic solvent-based liquid phase microextraction (DES-LPME). A green solvent was used to extract lead from the aqueous solution. Parameters affecting the extraction efficiency and determination were optimized in the aim to lower the detection limit. Under the optimum experimental and instrumental conditions, the proposed method exhibited a linear range between 50 and 1000 µg L−1, and the limits of detection and quantitation (LOD and LOQ) were found to be 8.7 and 29.0 μg L−1, respectively. The detection power was improved by 48 times using DES-LPME-SQT-FAAS method with respect to conventional FAAS system. Recovery studies were carried out in raw milk samples to check the accuracy and the applicability of the developed method and the percent recoveries obtained were between 102.5 and 103.2% for the spiked raw milk samples.

A novel and simple deep eutectic solvent based liquid phase microextraction method for rhodamine B in cosmetic products and water samples prior to its spectrophotometric determination

A novel and green deep eutectic solvent based liquid phase microextraction (DES-LPME) methodology has been proposed for the assessment of rhodamine B from cosmetic products and water samples. A deep eutectic solvent (DES) consist of tetrabutyl ammonium chloride-decanoic acid (1:2) as extraction solvent and tetrahydrofuran as emulsification agent were used for the microextraction of rhodamine B. The quantitative recoveries were achieved at pH 3 by using 0.3 mL of DES and 0.3 mL of THF. The rhodamine B concentration in last volume was analyzed by mirco-cuvette UV-VIS spectrophotometer at 550 nm. The limit of detection (LOD), limit of quantification (LOQ), preconcentration factor (PF) and relative standard deviation (RSD %) were found as 2.2 μg L−1, 7.3 μg L−1, 25 and 2.3%, respectively. Accuracy and validity of the developed method was verified by addition-recovery studies for water and cosmetic samples.

Deep eutectic solvent-based liquid-phase microextraction for detection of plant growth regulators in edible vegetable oils

A series of tunable DESs were prepared and used for the liquid-phase microextraction of plant growth regulators, including indole-3-acetic acid, indole-3-butyric acid and 4-iodophenoxyacetic acid, from a multi-component edible vegetable oil matrix.