Solvent-based Liquid Phase Microextraction Research Articles

Natural deep eutectic solvent-based liquid phase microextraction in a 3D-Printed millifluidic flow cell for the on-line determination of thiabendazole in juice samples.

At present, 3D printing technology is becoming increasingly popular in analytical chemistry because it enables the rapid and cost-effective manufacture of sample preparation devices, particularly in flow-based operation, opening up new opportunities for the development of automated analytical methods. In parallel, the use of miniaturized methods and sustainable solvents in sample preparation is highly recommended. Accordingly, in this work, a 3D-printed millifluidic device was designed and used for the on-line natural deep eutectic solvent (NADES)-based liquid phase microextraction (LPME) coupled to a spectrofluorometer for, as a proof of concept, the determination of thiabendazole (TBZ) in fruit juice samples. The millifluidic device was 3D printed by stereolithography and consisted of two patterned plates, each containing a millichannel (acceptor and donor channel). The millichannels were separated by a polypropylene membrane impregnated with optimal NADES, acting as a supported liquid membrane (SLM). Among the NADES investigated, formic acid:L-menthol (1:1M ratio) was selected as the SLM, avoiding the use of conventional harmful organic solvents. The proposed millifluidic device was successfully applied to the determination of thiabendazole in fruit juice samples, achieving LOD and LOQ values of 0.45μgL-1 and 1.42μgL-1, respectively, which are well below the maximum residue levels (MRLs) set by the European Union. The greenness and applicability of the proposed analytical method were evaluated using the AGREEPrep, SPMS and BAGI tools and compared with other published methods. In general, the proposed method was superior to others, mainly due to its high sensitivity and high sample throughput. Several cells were easily designed with different channel geometries (length and depth) to find the optimal dimensions, and then 3D printed and tested in a relatively fast, cheap and simple way, demonstrating the suitability of 3D printing in the fabrication of millifluidic devices as an alternative to traditional fabrication techniques. In addition, the proposed approach is fully compatible with new sustainable solvents, facilitating the development of green sample preparation methods.

Medium/Long Chain Hydrophobic Deep Eutectic Solvent-Based Liquid Phase Microextraction for the Determination of Rhein, Emodin, and Chrysophanol with Detection by High-Performance Liquid Chromatography (HPLC)

Medium/long-chain fatty acids/alcohols as hydrogen bond donors coupled with methyltrioctylammonium chloride were used to prepare hydrophobic deep eutectic solvents (DESs) that were employed for the extraction of the anthraquinones (rhein, emodin, and chrysophanol) from fetal bovine serum. Hydrophobic DES-based liquid-phase microextraction and high-performance liquid chromatography were developed. The most suitable combination was optimized for liquid-phase microextraction. Spiked fetal bovine serum was analyzed with satisfactory extraction recoveries.

Development of liquid phase microextraction-based deep eutectic solvent for the extraction and determination of toxic metal ions in herbal medicines

Herein, an eco-friendly, simple, and inexpensive procedure was developed using vortex-assisted combined with deep eutectic solvent-based liquid phase microextraction (VA-LPME-DES) followed by graphite furnace atomic absorption spectrometry. In the present procedure, DES was first synthesized from the combination of l-menthol and (1S)-(+)-camphor-10-sulfonic acid (CSA) in a molar ratio of 5:1, and then it was used as a green and safe extractant instead of common toxic organic solvents. The ability of the presented method was applied for the separation and preconcentration of lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As) in herbal medicines. After optimizing all the parameters of the experiment, the linear ranges were 0.10–200 µg kg−1 with coefficient of determination (r 2) better than 0.985. The limits of detection were in the ranges of 0.03–0.15 µg kg−1. Relative standard deviation values for intra-day and inter-day of the method based on 7 replicate measurements were in the range of 1.8%–3.6% and 3.1%–7.3%, respectively. The relative recoveries of herbal medicines which have been spiked with different concentrations of metal ions were 91.5%–109.8%. The method was successfully used to analyze the heavy and toxic metals in herbal medicine samples.

PH-switchable hydrophobic deep eutectic solvent-based liquid phase microextraction for detecting morphine and codeine in whole blood samples followed by HPLC-UV

Prescription opioids are used in clinics for reducing pain, but overdoses and addiction can lead to poisoning. Herein, we report a rapid, straightforward, and cost-effective hydrophobic deep eutectic solvent-based liquid phase microextraction process with HPLC-UV detection for extracting and analyzing morphine and codeine from whole blood samples. The procedure involved synthesizing seven deep eutectic solvents and investigating their pH switchability. Deep eutectic solvents with pH-switchable properties were employed as extractants. Under optimal conditions, the relative standard deviation of 50 μg/L of morphine and codeine in blood samples was 5.4–6.2 % for inter-day measurements and 3.7–4.3 % for intra-day measurements. For both analytes, the calibration graphs showed a linear range of 1.5–300 μg/L and a limit of detection of 0.5 μg/L. The enrichment factor and the extraction recovery of morphine and codeine were 152–––166 and 76 − 83 %, respectively. The results revealed that the addicted person’s blood sample contained both morphine and codeine. The real blood samples spiked with varying doses of codeine and morphine had relative recoveries ranging from 91.8 to 107.0 %, suggesting the method is suitable for real sample analysis.

Development of a vortex-assisted switchable-hydrophilicity solvent-based liquid phase microextraction for fast and reliable extraction of Zn (II), Fe (II), Pb (II), and Cd (II) from various baby food products

This manuscript describes the development of a novel liquid phase microextraction (LPME) method for the extraction and determination of Zn (II), Fe (II), Pb (II), and Cd (II) in various infant/baby food and supplements products. The method is based on vortex-assisted extraction combined with a switchable-hydrophilicity solvent (SHS) sample preparation. The SHS, which undergoes reversible phase changes triggered by pH change, enables selective extraction and easy phase separation. A flame atomic absorption spectroscopy was used in the final determination step. Optimization studies revealed, that the optimal pH of the sample solution (after digestion) during analytes extraction is 5.5. A l-proline is added to the sample (375 mM) to ensure the complexation of the target metal cations. After the complexation step, 750 µL of SHS - a N, N-Dimethylcyclohexylamine along with 0.9 mL of 2 M of acetic acid solution is added (hydrophilicity switch-on stage) and mixed manually to obtain a homogeneous solution. In the last stage, 0.45 mL of 10 M NaOH solution (hydrophilicity switch-off stage) is added to the sample solution and a vortex for 100 s is applied to ensure the effective extraction and separation of the complex containing the analytes. At this stage, a cloudy solution is immediately obtained. Finally, the effective phase separation is obtained at the centrifugation step (4000 rpm for 2 mins). The method limit of detection was as 0.03, 0.009, 0.6, and 0.2 ng/L for Zn (II), Fe (II), Cd (II), and Pb (II) respectively with RSD% below 2.0 %. The analysis of certified reference materials and real samples proved the full applicability of the method for routine analysis, contributing to the field of heavy metal analysis and ensuring the safety of baby products. According to the AGREE methodology, this method can be named as green analytical chemistry method with a score of 0.77.

Removal of two antidepressant active pharmaceutical ingredients from hospital wastewater by polystyrene-coated magnetite nanoparticles-assisted batch adsorption process.

This study employed simple polystyrene-coated magnetite nanoparticles (PS@MNPs)-assisted batch adsorption process for the removal of two antidepressant active ingredients (amitriptyline HCl and sertraline HCl) from hospital wastewater. Dominant parameters of the adsorption process including pH, adsorbent amount, and contact period were optimized through the univariate approach to enhance the adsorption efficiency. Upon reaching optimum adsorption conditions, equilibrium experiments were performed by spiking the adsorbates in hospital wastewater in the concentration range of 100-2000 μg/L. The concentrations of the adsorbates in the effluent were calculated using the matrix-matching calibration strategy to enhance the accuracy of quantification. A validated switchable solvent-based liquid phase microextraction (SS-LPME) method was employed to enrich the two active pharmaceutical ingredients (APIs) prior to sensitive determination with GC-MS (gas chromatography-mass spectrometry). The equilibrium data were mathematically modeled employing the Langmuir and Freundlich adsorption isotherm models. The isotherm constants were calculated, and the results showed that both the isotherm models fitted well with the experimental data. The efficient and simple batch adsorption strategy reported in this study was successfully employed to remove amitriptyline HCl and sertraline HCl from hospital wastewater at low concentrations.

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.

Development of a new method for determination of bisphenol A based on stirrer-assisted switchable hydrophilic solvent-based liquid phase microextraction coupled with electrochemical sensor

In this work, a novel stirrer-assisted liquid-phase microextraction method using switchable hydrophilic solvents was developed for the extraction and preconcentration of bisphenol A from real samples prior to electrochemical analysis. For the first time, the effect of stirring while switching the extraction solvent (N,N-dipropylamine, DPA) was investigated, and the use of stirring instead of temperature change, which is a time-consuming process, hazardous acids (e.g., HCl), and dry ice was used for bisphenol A extraction based on switchable solvents. Various parameters such as solvent type, solvent volume, stirring time, and stirring speed were optimized. The optimized conditions were 100 μl DPA, 2 min extraction time, 30 s stirring time, 700 rpm stirring speed, and solution pH of 7.0. A theoretical study was also conducted to show the effects of stirring on the homogenization of the phases. The proposed method offers some advantages, such as simplicity, use of a small amount of inexpensive and less hazardous reagents, rapid extraction, and shorter analysis time. Under the optimized conditions for the developed method, LOQ and LOD were obtained to be 0.01 and 0.003 μM, respectively. Moreover, the calibration curves were linear in the range of 0.01–250 μM. The proposed method was used for the determination of bisphenol A in food and water samples.

Switchable-hydrophilicity solvent-based liquid phase microextraction for determination of brilliant green in water, shellfish, and fish samples

To avoid substances harmful to the environment and humans, reducing residues generated during chemical tests and substituting solvents has attracted much interest from the scientific community. This study introduces an innovative approach, harnessing switchable-hydrophilicity solvent-based liquid phase microextraction to determine brilliant green. The microextraction process is based on the dispersion of a switchable-hydrophilicity solvent (octanoic acid) for the preconcentration of brilliant green. The alternation between these two forms, hydrophobic (immiscible) and hydrophilic (miscible), can be obtained by changing the composition of the solution, where sodium bicarbonate and sulfuric acid were employed. Factors such as pH, sample volume, switchable solvent volume, and acid-base ratio were optimized to obtain the best analytical response for brilliant green preconcentration. The detection limit was 1.4 μg/L, and the enrichment factor was 250. This novel method successfully assessed brilliant green levels in water, shellfish, and fish samples. It emerges as an accessible, cost-effective, and eco-conscious alternative for quantifying brilliant green, aligning seamlessly with the mission to protect the environment and human health.

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 effervescence-assisted switchable deep eutectic solvent based liquid-phase microextraction of triazole fungicides in drinking water and beverage

A new effervescence-assisted switchable deep eutectic solvent-based liquid phase microextraction (EA-SDES-LPME) combined with HPLC-UV was developed for determination of common triazole fungicides in drinking water and beverages, including myclobutanil, flusilazole, hexaconazole and bitertanol. The alternative extraction solvent was prepared with hexafluoroisopropanol and dipropylamine with the merits of time-saving, easy to collect and cost-effectiveness. The SDES can be reversibly switched between hydrophilic and hydrophobic states by pH adjustment. The homogeneous extraction was achieved under the hydrophilic form of SDES, and the bi-phase separation was obtained easily by adjusting pH value to restore the original hydrophobicity. Moreover, the characterization of SDES was investigated by FTIR and 1H NMR. The main variables affecting extraction efficiency were optimized in detail. Under the optimal conditions, the proposed method shows desirable precision (RSDs less than 18.5%) and acceptable recovery (72.6–95.4%). The lower limits of detection and limits of quantitation were found to be in the range of 1–2 μg L-1 and 5–10 μg L-1, respectively. The formation mechanism of SDES and the extraction mechanism for target analytes were investigated by density functional theory. The proposed methodology was simplicity, sensitive, time-saving and successfully applied to determine triazole fungicides in drinking water and beverages, making it an alternative technique for the analysis of trace analytes with satisfactory sensitivity.

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.

A new sample treatment strategy based on supramolecular solvent for determination of herbicide residues in water samples by Box-Behnken design

This paper describes a sensitive, simple and green analytical method for pretreatment of sulfonylurea and pyrethroid herbicides in water samples by supramolecular solvent-based liquid phase microextraction (SUPRAS-LPME). The SUPRAS was rapidly formed by nonanoic acid and tetrahydrofuran (THF)/water solution. The attractive features of SUPRAS-LPME include the simplicity, high enrichment factor, low cost and less consumption of organic solvents. The main influencing factors including type and volume of fatty acids, volume of THF, ionic strength, vortex time and volume of formic acid were optimized in detail, and then the significant variables were optimized by Box-Behnken design (BBD). Under the optimized condition, the proposed method shows high precision (RSDs < 13.7 %), low limits of detection (0.5–10 μg L-1) and limits of quantitation (10–45 μg L-1), acceptable recovery (71.3 %-95.9 %). The proposed method was successfully applied for analysis of sulfonylurea and pyrethroid herbicides in water samples, making it an alternative analytical strategy for determination of trace analytes at the microgram per liter range with desirable sensitivity.

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%.

Determination of rhodamine B in water and cosmetics by switchable solvent-based liquid phase microextraction with spectrophotometric determination

A microextraction method has been developed for the determination of rhodamine B (Rh-B) in water and cosmetics by separation and preconcentration with liquid microextraction based upon a switchable hydrophilic solvent and determination by spectrophotometry. The analyte was extracted into the triethylamine (TEA) phase using sodium hydroxide (NaOH) to convert protonated triethylamine carbonate (P-TEA-C) to triethylamine. Various analytical parameters such as the pH of the sample solution, extraction solvent volume, and sample volumes affecting the quantitative recovery values of rhodamine B were optimized. The limit of detection (LOD) and limit of quantification (LOQ) were 2.96 and 9.88 ng/mL, respectively. The developed method was successfully applied to the determination of rhodamine B and satisfactory recovery values were obtained. The developed approach is fairly fast and an environmentally friendly alternative for the separation and preconcentration of rhodamine B water and cosmetic samples.

Chemometric design-based optimization of a green, selective and inexpensive switchable hydrophilicity solvent-based liquid phase microextraction procedure for pre-concentration and extraction of sulfadiazine in milk, honey and water samples

In this research, a green, selective and inexpensive switchable hydrophilicity solvent-based liquid phase microextraction (SHS-LPME) procedure has been optimized for the extraction and preconcentration of sulfadiazine (SDZ) in milk, honey and water samples prior to spectrophotometric analysis. Five variables affecting the SHS-LPME procedure were optimized using chemometric-based central composite design. For the SHS-LPME procedure, analytical parameters such as linearity, limit of detection, extraction recovery and enrichment factor were 15–300 μg L−1, 4.5 μg L−1, 96 ± 3% and 113, respectively. The precision of the method was investigated by repeatability and reproducibility studies. The relative standard deviation from these studies was found in the range of 2.4–4.5%. The recovery of the SDZ in the samples was in the range of 94 ± 4–99 ± 2%. Collected samples were analyzed by both the SHS-LPME procedure and the reference method using flow injection-flame atomic absorption technique, and the results were compared. There was no statistically significant difference between the two methods. This showed that the SHS-LPME procedure can be safely applied to the analysis of real samples.

Recent developments in microextraction techniques for detection and speciation of heavy metals

Analysis of heavy metals and their species in complex samples such as environment, biology and medicine is be of paramount importance due to their toxicity, persistence, and bioaccumulation. Considering the complexity of the sample matrix and the low concentration of heavy metals, sample preparation step should be exerted before analysis. Microextraction techniques have received extensive attention due to its miniaturization, quickness, low cost, environmental friendliness, and satisfactory extraction performance. So far, various formats based on microextraction techniques have been developed and applied to entrap heavy metals and related species. This review mainly concentrates on the recent development and applications of microextraction techniques including solvent-based liquid-phase microextraction and sorbent-based solid-phase microextraction for the detection and speciation of heavy metals in water, food, sediment, soil, hair, urine, and serum samples.

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.

Trace level determination of eleven nervous system-active pharmaceutical ingredients by switchable solvent-based liquid-phase microextraction and gas chromatography-mass spectrometry with matrix matching calibration strategy.

This study utilized switchable solvent liquid-phase microextraction (SS-LPME) to enrich eleven nervous system active pharmaceutical ingredients (APIs) from aqueous samples for their determination at trace levels by gas chromatography mass spectrometry. The analytes selected for the study included APIs utilized in antidepressant, antipsychotic, antiepileptic, and anti-dementia drugs. Parameters of the microextraction method including switchable solvent volume, concentration and volume of the trigger agent (sodium hydroxide), and sample agitation period were optimized univariately to boost extraction efficiency. Under the optimum conditions, the detection limits calculated for the analytes were in the range of 0.20-8.0ng/mL, and repeatability for six replicate measurements as indicated by percent relative standard deviation values were below 10%. Matrix matching calibration strategy was used to enhance quantification accuracy for the analytes. The percent recovery results calculated for the eleven analytes ranged between 86 and 117%.