Liquid-phase Microextraction Research Articles

Switchable deep eutectic solvent as green and efficient media for liquid-phase microextraction of phenoxyacetic acid herbicides in water and food matrices

In this work, a switchable deep eutectic solvent (SDES) based on fatty acid and polyetheramine ion pair was prepared for liquid-phase microextraction (LPME) of phenoxyacetic acid herbicides in drinking water, beverage and honey matrices. The as-synthesized SDES equipped with an interesting characteristic of fast and reversible polarity switching, achieving homogeneous extraction and rapid bi-phase separation simultaneously. Several key parameters affecting the extraction performance were investigated comprehensively by Box-Behnken design. Under the optimal conditions, the method exhibited excellent linearity (15–4000 μg L−1), low detection limits (3–5 μg L−1), desirable precision (RSD < 8.1 %), and satisfactory recovery (72.6–98.7 %). More importantly, the introduction of SDES can simplify the pre-treatment procedure, shorten extraction time (4 min), and avoid the usage of traditional organic solvent during the whole extraction process. In addition, the switching mechanism of SDES was characterized by FT-IR and 1H NMR, and the forming mechanism of SDES was investigated using density-functional theory. The green of the method was estimated using the analytical ecological scale, the analytical green calculator, and the green analytical procedure index. The cytotoxicity of SDES was investigated and the result displayed that toxicity of the SDES was very low with the EC50 > 500 mg/L. Therefore, the proposed method was green and efficient and revealed considerable application prospects for the extraction of trace analytes from complex materials.

Implementation of simple and effective fine droplet formation-based spray-assisted liquid phase microextraction for the simultaneous determination of twenty-nine endocrine disruptor compounds and pesticides in rock, soil, water, moss, and feces samples from antarctica using gas chromatography-mass spectrometry

This study established the simultaneous determination of the selected endocrine-disrupting compounds (EDCs) and pesticides in rock, soil, water, moss, and feces samples collected from the Antarctic region. The spray-assisted droplet formation-based liquid phase microextraction (SADF-LPME) coupled to GC–MS system was developed and validated for the screening and monitoring of 29 selected EDCs and pesticides. Binary solvent system, 1:1 (v/v) dichlormethane: 1,2-dichloroethane mixture was employed as an extraction solvent and sprayed onto sample or standard solutions using a straightforward and practical spray apparatus. The factors affecting the extraction process such as extraction solvent type and ratio, extraction solvent volume (spray repetition), vortexing period, and sample pH were properly optimized. Analytical figures of the merit of the method were recorded under the optimal extraction/chromatographic conditions. The LOD, LOQ, and enhancement factor were in the range of 1.0 to 6.6 ng/g, 3.2 to 22.1 ng/g, and 3.7 to 158.9, respectively. The method demonstrated a good linear working range for all the selected analytes with proper coefficients of determination. The usability and reliability of the microextraction strategy was confirmed using seawater, moss, and soil samples, and the %recoveries were within an acceptable range (> 70%) for all examined samples. The environmental samples collected from the Horseshoe and Faure Islands of the Antarctica region were analyzed to assess the potential pollution of EDCs and pesticides. This method has the potential to be employed for the analysis of EDCs in routine analytical laboratories and for controlling and screening the organic pollutant content of different environmental samples.

The selective extraction of dietary polyamines from chicken breast using the application of a lab-on-a-chip electromembrane and dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

Excessive dietary polyamines (PAs), including putrescine (PUT), spermine (SPM), and spermidine (SPD), have become a worldwide concern due to their carcinogenicity and reduced shelf life. A modern miniaturized on-chip electromembrane extraction (EME) has been applied to extract these compounds from chicken breast samples. This method is based fundamentally on ionic compounds' electrostatic attraction, diffusion, and solubility in the acceptor phase. The chemical structure of polyamines enables their efficient extraction using an electric driving force on a microchip device. HCl solution (0.1 mol L-1) was applied as an aqueous acceptor solvent. Dispersive liquid-liquid microextraction was performed after EME to facilitate joining three-phase EME to GC-MS and improve the merit figures. The total ranges of 3.77-7.89 μg g-1, 3.48-7.02 μg g-1, and 0.78-2.20 μg g-1 were acquired as PUT, SPM and SPD concentrations in chicken breast, respectively. The results demonstrate that the level of PAs in fresh chicken breast samples is not concerning, but it may reduce the quality of chicken meat over time. This novel analytical technique has several advantages: high recovery, substantial quickness, remarkable selectivity, and good enrichment factors. This emerging method could be generalized to other studies to analyze different foodstuffs.

Hydroxyl-rich ferrofluid for efficient liquid phase microextraction of cinnamic acid derivatives in traditional Chinese medicine.

In this study, a hydroxyl-rich ferrofluid was prepared by dispersing silica-coated magnetic nanoparticles into a methyltrioctylammonium chloride-glycerol deep eutectic solvent and then employed in the preconcentration of trace-level of cinnamic acid derivatives (caffeic acid, p-hydroxycinnamic acid, ferulic acid, and cinnamic acid) in traditional Chinese medicine prior to high-performance liquid chromatography analysis. The structures of the synthesized materials were characterized by X-ray diffraction and infrared spectroscopy. The experimental parameters affecting the extraction performance, such as deep eutectic solvent composition, dosage of ferrofluid, pH of aqueous sample solution, salt concentration, extraction time, type, and volume of desorption solvent, were studied and optimized. Under the optimum conditions, the enrichment factors of four cinnamic acid derivatives were in the range of 107-114. Low detection limits (0.2-0.9ng/mL), good precisions (relative standard deviations 1.2%-9.5%), and satisfactory recoveries (96.0%-104.7%) were achieved. Subsequently, the possible microextraction mechanism of the proposed method was explored and elucidated. It showed that the prepared ferrofluid is easily dispersed in the aqueous sample and achieved recovery after the extraction. The developed approach is a simple, convenient, and efficient method for preconcentration and determination of cinnamic acid derivatives in complex matrices.

A fast and simple procedure for the synthesis of a zinc and 1,4-benzene dicarboxylic acid metal-organic framework and its evaluation as a sorbent for dispersive micro solid phase extraction of pesticide residues.

In this work, Zn-1,4-benzenedicarboxylate metal-organic framework was synthesized by a simple hydrothermal process and used in dispersive micro solid phase extraction of some pesticide from various fruit juice and water samples. Seven widely consumed pesticides in agriculture (chlorpyrifos, haloxyfop-R-methyl, oxadiazon, diniconazole, clodinafop-propargyl, fenpropathrin, and fenaxoprop-p-ethyl) were selected as target analytes. In this work, dispersive micro solid phase extraction was followed by a liquid phase microextraction method to achieve more enrichment of the analytes, and the enriched analytes were quantified using a gas chromatography-flame ionization detector. The sorbent was authenticated by Fourier transform infrared spectrophotometry, X-ray diffraction, energy dispersive X-ray analysis, and scanning electron microscope imaging. The factors affecting the extraction efficiency of the developed method were investigated, and the validation of the method under the optimized extraction conditions presented satisfactory results for precision and trueness, with limits of detection and quantification in the ranges of 0.50-0.90 and 1.5-2.7 μg L-1, respectively. Enrichment factors and extraction recoveries were in the ranges of 239-392% and 47-78%, respectively. One river water and some fruit and vegetable juice samples were analyzed by the recommended method, and the obtained recoveries were between 90% and 102%.

Supramolecular Solvent-Based Vortex-Assisted Hollow Fibre Liquid-Phase Microextraction Technique Combined With High Performance Liquid Chromatography for the Determination of Estrogens in Milk Samples

A fast, simple, environmental friendly and strong sample clean-up ability method for the determination of three estrogens (17β-estradiol (17β-E2), estrone (E1), and diethylstilbestrol (DES)) in milk samples has been developed by using supramolecular solvent-based vortex-assisted hollow fibre liquid-phase microextraction (SS-VA-HF-LPME) and high performance liquid chromatography. Method is based on estrogens was extracted from aqueous samples into a supramolecular solvent which were made up of n-octanol and ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM] BF4) impregnated in the wall pores and also filled inside the porous polypropylene hollow fiber membrane followed by vortex-mixing. The supramolecular solvent has better compatibility with the polarity of target analytes and the driving forces for the extraction include hydrogen bonding, hydrophobic and π-cation interactions between the analytes and the vesicular aggregates, thereby leading to high recoveries. Vortex can provide mild and effective mixing of sample solution and increase the contact between analytes and boundary layers of the hollow fibre. Therefore the mass transfer rate was enhanced. The parameters that affect the recoveries were studied and optimized. HF of 4 cm length was used and the pH 4.0 was employed. The percentages of n-octanol and [BMIM]BF4 were 10% and 3%, respectively. The extraction equilibrium time was 4 min. The method provided good linearity (andgt;0.998), repeatability (RSD% = 1.24–4.36), low detection limit (0.10–0.22 ng mL−1), and high enrichment factor (330).

Kinetic Modeling of Electromembrane Extraction of Copper using a Novel Electrolytic Cell Provided with a Supported Liquid Membrane

The aim of this study is to investigate the kinetics of copper removal from aqueous solutions using an electromembrane extraction (EME) system. To achieve this, a unique electrochemical cell design was adopted comprising two glass chambers, a supported liquid membrane (SLM), a graphite anode, and a stainless-steel cathode. The SLM consisted of a polypropylene flat membrane infused with 1-octanol as a solvent and bis(2-ethylhexyl) phosphate (DEHP) as a carrier. The impact of various factors on the kinetics constant rate was outlined, including the applied voltage, initial pH of the donor phase solution, and initial copper concentration. The results demonstrated a significant influence of the applied voltage on enhancing the rate of copper mass transfer across the membrane. As the applied voltage increased, the rate constant also increased. Additionally, increasing the pH of the solution led to an initial elevate in the rate constant, reaching a maximum value at pH 5, after which it started to decline. Moreover, higher initial copper concentrations had an adverse effect on the rate constant. Notably, the concentration decay profiles observed under different operating conditions followed first-order kinetics, with correlation coefficients exceeding 0.99. The elucidation of this discovery emanated from a remarkable and striking congruence between the experimental data and the mathematical underpinnings of the first-order kinetics model. This serendipitous alignment profoundly reinforced the robustness, veracity, and unwavering reliability of meticulously obtained results, amplifying the credibility and trustworthiness of the present comprehensive study.

Determination of copper ion at trace levels in apple tea samples by simultaneous complexation and spray assisted microextraction method prior to detection by flame atomic absorption spectrophotometry

In the present study, a green and sensitive analytical method for the determination of copper ion at trace levels in apple tea samples was developed. Simultaneous complexation/extraction of the analyte were achieved by spraying-based fine droplet formation liquid-phase microextraction (SFDF-LPME). Copper ion was complexed with a Schiff base chelating agent called as N,N′-Bis(salicylidene)-1,2-phenylenediamine (BSP). Under the optimum conditions, the developed SFDF-LPME-FAAS and FAAS system were assessed with respect to limit of detection (LOD), limit of quantitation (LOQ), linearity and percent relative standard deviation (%RSD). LOD and LOQ values for SFDF-LPME-FAAS method were found to be 6.0 and 19.9 µg/kg, respectively. Enhancement in calibration sensitivity for developed method was found as 23 folds. In addition, accuracy/suitability of the developed SFDF-LPME-FAAS method were confirmed by spiking experiments. Two different apple tea samples were spiked to different concentration values and percent recovery results from 91.1 and 123.8 % proved the accuracy/suitability of the method.

Artemisia argyi essential oil as a green extraction solvent for in-syringe kapok fiber-supported liquid-phase microextraction and determination of triazole fungicide residues

In this study, Artemisia argyi essential oil (AAEO), extracted from the leaves of Artemisia argyi, was employed as a green extraction solvent for in-syringe kapok fiber-supported liquid-phase microextraction (KF-SLME) of hydrophobic compounds in aqueous samples. The wheat of natural kapok fiber as the support medium was 2 mg, and the optimum volume of the extraction solvent AAEO was 12.5 μL. The volume of green desorption solvent 75 % ethanol was 100 μL, which realized a highly environmentally friendly sample preparation method. By simply pulling and pushing the syringe plunger five times, the extraction process enabled rapid and convenient enrichment of analytes while removing most interferences. Coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), the AAEO-based in-syringe SLME method was applied as a proof-of-concept study to determine triazole fungicides (TFs) residues in fruit juices, herbal oral liquids and herbal extract granules. Employing in-syringe KF-SLME prior to LC-MS/MS detection significantly reduced the limits of quantification (LOQs) by 5–50-fold. The integrated AAEO-based in-syringe KF-SLME-LC-MS/MS method demonstrated satisfactory linearity (R2 ≥ 0.995), accuracies (86.5 %–115.1 %), and precisions (1.2 %–12.7 %) using an isotope calibration method. Furthermore, three greenness assessment metrics uniformly highlighted its outstanding environmental friendliness. The proposed method offers competitive advantages in terms of its environmentally friendly approach, detection sensitivity, analysis cost, and operational convenience.

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.

Simultaneous analysis of three metal ions on a single chip: Easy clean-up with bio-thin film in electromembrane extraction and quick colorimetric analysis with progressive web application

In this study, a miniaturized on-chip electrically assisted membrane transport based on starch/gelatin thin-film, as a novel composite carbohydrate polymer, was introduced for the simultaneous determination of three heavy metal ions with an emphasis on green chemistry. The starch/gelatin membrane is environmentally friendly, has low cost, and can be used as a solvent-free membrane for ion transport and matrix cleanup. Metal ions were extracted by applying a low voltage across the membrane sheet. The acceptor droplets are specific ligand solutions that can form selective color complexes on the colorless membranes to indicate the presence of metal ions. The color response of the final acceptor droplets was evaluated by acquiring several digital images and processing them with specific software developed as a Progressive Web Application. For Ni(II), Cr(VI), and Cu(II), the limits of detections were 0.5, 0.5, and 0.1 mg/L, and limits of quantifications were 1.0, 1.0, and 0.5 mg/L, respectively. The calibration range is from 1.0 to 50.0 mg/L for Ni(II) and Cr(VI), while it is from 0.5 to 50.0 mg/L for Cu(II) with relative recoveries ranging from 86.6 to 113.3% and relative standard deviations less than 11.0%. The values obtained with AGREE and AGREEprep methods were 0.68, and 0.5, thus indicating a proper level of greenness for the proposed method. Finally, this method was successfully applied for measuring metal ions in solutions of acidified digested vegetables including lettuce, carrot, potato, and onion.

Electromembrane extraction based on a fabricated novel carrier-mediated gel membrane: Determination of fluoroquinolones residue in urine and wastewater samples

This study reports the fabrication and application of green material, pectin gel containing cationic carrier agent as a green membrane in electromembrane extraction of polar fluoroquinolones for the first time. In this study, apple pomace pectin gel has been used with a low esterification degree (29 %) containing cetyl tributyl ammonium bromide at a concentration lower than its critical micelle concentration as a cationic carrier and ion-pairing agent as a gel membrane for electromembrane extraction of polar fluoroquinolones, levofloxacin and ciprofloxacin from urine and wastewater samples successfully. To make a gel membrane, pectin is dissolved in hot water along with the ionic carrier cetyltrimethylammonium bromide, and a gel-like substance with the ability to be molded is obtained. The gel-like substance is molded in a warm state inside the Eppendorf microtube and after being placed in the refrigerator for hardening, the end of the microtube is cut and the gel membrane is ready to use. Under optimized conditions, the suggested method demonstrated low detection limits toward target analytes (0.003 and 0.025 ng/mL for levofloxacin and ciprofloxacin respectively), a wide linear dynamic range (0.02–1000 and 0.2–1000 ng/mL for levofloxacin and ciprofloxacin respectively), as well as high sample clean-up and proper precision (intra-day RSD 7.4–13.5 %).

Development of an effervescence‐assisted dispersive liquid phase microextraction using a binary solvent as a simultaneous extraction and preconcentration approach specialized for the analysis of pesticides in grape juice without dilution

AbstractIn this study, a swift and economical extraction and preconcentration method called effervescence‐assisted dispersive liquid‐phase microextraction was developed to analyze the pesticide content of different grape juices. To propel the microextraction method, the sample was transferred to a conical bottom glass test tube, and ammonium chloride was added and vortexed to dissolve. Then, sodium bicarbonate and a mixture of 1,2‐dibromoethane and n‐hexane were added. The tube was located in a water bath and the produced carbon dioxide bubbles dispersed the extraction solvent into the sample. Finally, it was centrifuged and one microliter of the sedimented phase was injected into a gas chromatograph equipped with a flame ionization detector. Under the optimum conditions, the limits of detection and quantification ranged from 0.9 to 4.1 and 3.0 to 13.6 μg/L, respectively. Extraction recoveries and enrichment factors were achieved in the ranges of 36%–80% and 180%–404%, respectively. The inter‐ and intra‐day relative standard deviations were in the ranges of 3.4%–10.6% and 2.6%–9.7%, respectively. Also, the coefficients of determination in the calibration curves were ≥0.990. Short extraction time, no sorbent or costly apparatuses, using inexpensive chemicals, applying microliter levels of the extractant, and no dilution of the real samples are the highlights of the study.

Parallel artificial liquid membrane extraction coupled with UPLC-ESI-MS/MS method for high-throughput quantitation of repaglinide in diabetic patients

A high-throughput therapeutic monitoring method was developed for repaglinide (RPG) in diabetic patients, combining parallel artificial liquid membrane extraction (PALME) with ultraperformance liquid chromatography electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). PALME was performed using a 96-well donor plate comprising a donor solution containing a plasma sample, 50 mM phosphate buffer (pH = 8.0), and cetirizine (CTZ) as internal standard. A polypropylene (PP) porous membrane served as a selective support for the liquid membrane (SLM), preventing nonspecific binding produced by other membranes. The extraction was accomplished across SLM made of PP membrane with dodecyl acetate and 1 % trioctylamine (w/w), and the acceptor solution comprised DMSO and 200 mM formic acid (50:50, v/v). The simple workflow for PALME provided analyte enrichment, highly efficient sample cleanup, high throughput analysis, and excellent reproducibility. Method validation met FDA criteria, with a linear plasma calibration range (0.1–100 ng mL−1, r = 0.9995) and a lower limit of quantitation (LLOQ) of 0.1 ng mL−1. Recovery results at 98.9 % affirmed method reliability. The ability to analyze 198 samples per hour, coupled with a reduced amount of solvents, underscores the method's high throughput and eco-friendly profile. The PALME-UPLC-ESI-MS/MS method was successfully applied to therapeutic drug monitoring of RPG in diabetic patients following 2 mg RPG tablet administration, establishing its effectiveness.

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.

Selective separation and determination strategy for monitoring E100, E127, E129 and E133 in foodstuffs: Vortex assisted sequential-simultaneous liquid phase micro-extraction

A green, speedy and handy, vortex assisted sequential-simultaneous liquid phase micro-extraction procedure (VA-SS-LPME) was established first time without using any instrumental chromatographic techniques for separation, preconcentration and spectrophotometric determination of four important popularly and widely used food colorants, namely curcumin (E100), erythrosine (E127), allura red (E129) and brilliant blue (E133). Here, n-nonanol and n-nonanol based deep eutectic solvent were used as extraction solvents. The procedure has included two simultaneous and sequential separation steps by different extractants and two simultaneous UV–vis spectrophotometric determination steps. First, simultaneous separation of E100 and E127 from aqueous solution containing E129 and E133 was achieved and then simultaneous separation of E129 and E133 from aqueous solutions was applied and simultaneous spectrophotometric determinations were performed finally for binary mixture dyes (E100 and E127) and (E129 and E133). The parameters including pH, types and amounts of extractants, vortex time and rate, centrifugation time and rate were investigated in detail for sequential two steps separation and quantitative simultaneous extraction of the dyes. Interference effect of matrix ions, target and other dyes were examined. Possible envisaged extraction mechanisms were elucidated. Green analytical procedure index (GAPI) and analytical eco-scale (AES) parameters of the procedure were determined. As last, E100, E127, E129 and E133 contents of some foodstuffs and pharmaceuticals such as confectioneries, beverages, drugs and syrups were determined by applying optimized procedure. Colourful food additive concentrations of real samples were determined between 2.9 and 93.8 µg/g and 5.3–112.4 µg/mL for solid and liquid samples, respectively.

The application of barcode readable assay and linear regression RGB analysis using a customized smartphone app in on-chip electromembrane extraction for simultaneous determination of heavy metal ions

This paper presents an on-chip electromembrane extraction (OC-EME) followed by RGB analysis with a barcode-readable customized app for the determination of three heavy metal ions; Cr(VI), Ni(ΙΙ), and Cu(ΙΙ) in water samples. First, the OC-EME procedure was performed on a single transparent platform including three divided channels for extraction of analytes and subsequently complex formation with chromogenic reagents. The RGB values of colorful complexes were then analyzed by Photoshop software and green value intensities of all three colors showed the best concentration dependence signal. Effective parameters such as the composition of supported liquid membrane (SLM), the voltage of extraction, the composition of donor and acceptor solutions, sample volume, and flow rate were investigated and optimized. Also, a smartphone app was developed for RGB analysis on a barcode-readable program to detect and quantify the extracted heavy metal(s). A fast, easy, and accurate quantification analysis was offered using principal component analysis (PCA) and a trained linear regression model. Under optimized conditions, good calibration fittings were observed within the ranges of 0.05–1.5 mg l−1 for Cr(VI), 1.0–70.0 mg l−1 for Ni(II), and 0.5–30.0 mg l−1 for Cu(II) via the customized app. Intra- and inter-day RSDs% of the method were obtained less than 6.9 % and 7.8 %, respectively. Finally, the proposed procedure was successfully applied for the analysis of target ions in water samples with relative recoveries between 85.0 % and 116.4 %.

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.

Primary amine citrate-based supramolecular designer solvent: Preconcentration of ochratoxin A for determination in foods by liquid chromatography

BackgroundSupramolecular solvents are nanostructured liquids that are separated from colloidal solutions of amphiphilic compounds as a result of self-assembly of amphiphiles and coacervation under changing conditions. They are considered to be designer solvents as their properties can be tailored to a specific analytical task by controlling the conditions of their formation (amphiphile, coacervation inducer, medium, concentration of components). The discovery of new extraction systems based on supramolecular solvents and their application to relevant analytical tasks are of great importance for the advancement of environmentally-friendly sample preparation. ResultsA novel green liquid-phase microextraction approach involving in situ formation of 1-octylamine citrate followed by preconcentration of ochratoxin A from aqueous extract of food sample in supramolecular solvent droplets was developed. The extraction system was carefully characterized. The density of the solvent allowed it to be to retrieved from the extraction system by its solidification. The alkaline nature of the obtained extract allowed the use of acetic acid for its dissolution instead of more toxic organic solvents followed by high-performance liquid chromatography with fluorometric detection. An excellent extraction recovery of 99 % and a satisfactory enrichment factor of 8.3 were achieved. The limit of detection was 0.5 μg kg−1, while the calibration plot was linear over the range of 1.5–50 μg kg−1. Cereal and roasted coffee bean samples were successfully analyzed with a relative bias less than 20 %. SignificanceIn the present work, a phenomenon of supramolecular solvent formation based on primary amine citrate was presented for the first time. Tetrabutylammonium bromide was investigated as a coacervation agent in an extraction system, and possible interactions responsible for its ability to induce phase separation in a micellar solution of primary amine citrate were described. The critical micelle concentration of 1-octylamine citrate in aqueous solution of tetrabutylammonium bromide was firstly determined.

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.