Ionic Liquid-based Dispersive Liquid-liquid Microextraction Research Articles

Handshake of deep eutectic solvent and ionic liquid: Two liquid-liquid microextraction procedures for plant analysis

Plants are subjects of interest due to the secondary metabolites in their extracts which are promising as new pharmaceuticals. Phytochemistry do not have united system of sample preparation or analysis still due to different structure of plant cells, wide broad range of chemical properties and concentrations of bioactive compounds. Such challenges can be addressed in a green chemistry manner using new approaches through smart materials in routine monitoring and researches. Liquid smart materials, such as ionic liquids (ILs) and deep eutectic solvents (DESs) are attractive due to flexible properties, lots of extraction approaches, recycle potential, and direct compatibility with powerful analytical methods.In this study DES-based microextraction procedure with pH-switching was developed. Four choline chloride DESs were suggested as selective extraction phases for polar compounds from acetonitrile extracts. Method was successfully tested on four plants (Iris sibirica L., Hypericum perforatum L., Scutellaria baicalensis G, Citrus reticulata B.). Developed procedure was optimized and validated for the choline chloride – urea (1:2 mol/mol) DES that demonstrated better results in extraction. LOD for rutin was found as 0.05 mg ml−1. For low-polar compound, imidazolium ionic liquid-based dispersive liquid-liquid microextraction procedure was developed. 1-hexyl-3-methylimidazolium salts have demonstrated desired selectivity. The main factors influencing the extraction efficiency have been identified and optimized by design of experiment on two model plants (Iris sibirica L. and Scutellaria baicalensis G.). Validation procedures were done for thymol. LOD for thymol was found as 0.021 mg ml−1.The methods were compared with each other and traditional methanol extraction. The selectivity of the smart materials supports each other, usage of such extraction phases provides same or better results as obtained with methanol.

Efficient Green Solvent Extraction and Bioassay Studies of Favipiravir in Rat Dried Blood Spots Using Ionic Liquid-based Dispersive Liquid-liquid Microextraction (IL-DLLME) Coupled with HPLC-PDA: Application to Bioequivalence Studies

Background: Favipiravir is an antiviral drug having pyrazine group moiety. It is a reliable and an efficient green solvent, and a highly recoverable bio-sampling method is required for it. It is widely used in COVID-19 treatment for the prevention of the spread of viral infections in the body. Objective: This proposed green solvent (ionic liquid)-based bioassay study aimed to quantify favipiravir in rat-dried blood spots using Dispersive Liquid-liquid Microextraction (IL-DLLME). Methods: The proposed bioassay separation was achieved through an isocratic elution mode using a hybrid silica-based ODS column (250 × 4.6 mm; 5 μm), a column temperature of 25°C, an injection volume of 10 μL, a flow rate of 1.0 mL/min, and a detector wavelength set at 310 nm. The run time was less than 10 minutes. Mobile phase was delivered with acetonitrile, methanol, and 10 mM Na2HPO4 at pH 4.0 ± 0.5, (15: 20: 65, v/v/v). In a microtube, 50 mL of Ionic Liquid (IL), 500 μL of disperser ACN, 50 μL of 10% NaCl, and IS (20 ng mL-1) were added to perform the Dried Blood Spot (DBS) sample extraction methodology. The advantages of the proposed methodology have been found to include minimum hematocrit effect and an adequate blood volume for testing, easy transportation, and significant extraction recovery. The sample analysis has been carried out using HPLC-PDA with oseltamivir used as an internal standard. Results: We have investigated the important variables, i.e., salt concentration (10% NaCl, analyte recovery being higher) and disperser solvent [50μL of BMIHP plus 500 μL of ACN (v/v) yielding the highest recovery], in the extraction process. Extraction Recovery (ER) and Enrichment Factor (EF) were also evaluated using the IL-DLLME method. The calibration curve examined a range of 0.5-150 μg/mL, with a lower Limit of Quantification (LOQ) being 0.5 μg/mL in QC as well as calibration samples, respectively. Conclusion: Significant bioanalytical validation has been performed and all the parameters have been evaluated systematically as per bioanalytical method validation protocols, i.e., US FDA- 2018 guidelines. The following analytical parameters have been covered: standard curve, limit of quantification, range, recovery, stability, accuracy, precision, sensitivity, ER, EF, and selectivity. The developed bioassay method has been successfully applied in the pharmacokinetic studies of rats and successfully applied in bulk drugs.

Combination of distance-based paper analytical devices with ionic liquid-based dispersive liquid-liquid microextraction for enzyme-free bilirubin quantification

This article introduces the first demonstration of integrating distance-based paper analytical devices (dPADs) with ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) for the quantitative detection of bilirubin levels in human samples. In this approach, bilirubin is preconcentrated and extracted into a small droplet of the extraction solvent using IL-DLLME. The resulting solution is then introduced into an economical and straightforward dPAD sensor. Detection relies on a colorimetric reaction between bilirubin and gold ions (Au3+), leading to the in-situ formation of gold nanoparticles (AuNPs) on the paper substrate. The observed red-purple distance length is directly proportional to the bilirubin level. Under optimization, a linear range between 0.25 nM and 5.0 nM (R2 = 0.9979) and a detection limit (LOD) of 250.0 pM were achieved. The assay exhibits notable precision and selectivity without any interference. With its distance readout feature, this method is simpler and more cost-effective, offering greater sensitivity compared to other methods requiring expensive reagents and instruments. Moreover, the technique shows high accuracy and precision for bilirubin quantification in human control samples, with recoveries ranging from 98.33% to 102.00%. No significant difference was observed between our method and the enzyme-linked immunoassay (ELISA) method. By combining a low-cost microfluidic device with a simple microextraction method, this strategy holds great potential as an alternative analytical method for determining bilirubin. It can be expanded for further applications in analytical sensing for point-of-care (POC) diagnostics.

Ionic liquid-based dispersive liquid-liquid microextraction of anthelmintic drug residues in small-stock meat followed by LC-ESI-MS/MS detection.

An ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) of 20 anthelmintic drugs followed and detected by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed, optimized, and validated. The parameters affecting the anthelmintic extraction efficiencies such as selection of extraction solvent (ionic liquids), selection of disperser solvent, volume of extraction solvent, volume of disperser solvent, pH of the aqueous phase, extraction time, salt addition, and centrifugation time were optimized. Validation was conducted according to ISO/IEC 17025:2017 and Commission Implementing Regulation (EU) 2021/808 of 22 March 2021. Validation parameters such as calibration function, matrix effect, limit of detection (LOD), limit of quantification (LOQ), decision limit (CCα), accuracy, and precision were established. Coefficient of determination (R 2) values ranging from .99938 to .99995 were obtained using the matrix calibration curve spiked at 0, 0.25, 1.0, 1.5, and 2.0 times MRL. The LODs and LOQs were calculated using the standard deviation of the response and the slopes of the calibration curves ranged from 0.35 to 26.1 μg/kg and from 1.2 to 87.0 μg/kg, respectively, and were dependent on calibration range. The CCα values ranged from 23 to 1022.0 μg/kg and are also dependent on the MRL concentration levels. The coefficient of variation (CV) values calculated are within the reproducibility range of 16%-30% adapted from the Horwitz Equation CV = 2(1-0.5 log C) and ranged from 1.7% to 16.9%. The developed and validated and the standard QuEChERS method were compared. The IL-DLLME LC-MS/MS method was applied to 32 small stock (18 caprine [goat] and 14 ovine [sheep]) liver samples received from municipal abattoirs at Botswana National Veterinary Laboratory for the analysis of anthelmintic drug residues. The results obtained indicated that the anthelmintic drug residues were all below the detection capability, and therefore, the samples were passed as fit for human consumption.

Ionic liquid-based dispersive liquid–liquid microextraction of succinic acid from aqueous streams: COSMO-RS screening and experimental verification

ABSTRACT In the present investigation, a total of 108 combinations of ionic liquids (ILs) were screened using the conductor-like screening model for real solvents (COSMO-RS) with the aid of six cations and eighteen anions for the extraction of succinic acid (SA) from aqueous streams through dispersive liquid–liquid microextraction (DLLME). Using the screened ILs, an ionic liquid-based DLLME (IL-DLLME) was developed to extract SA and the role of different reaction parameters in the effectiveness of IL-DLLME approach was investigated. COSMO-RS results suggested that, quaternary ammonium and choline cations form effective IL combinations with [OH¯], [F¯], and [SO4 2¯] anions due to hydrogen bonding. In view of these results, one of the screened ILs, tetramethylammonium hydroxide [TMAm][OH] was chosen as the extractant in IL-DLLME process and acetonitrile was adopted as the dispersive solvent. The highest SA removal efficiency of 97.8% was achieved using 25 μL of IL [TMAm][OH] as a carrier and 500 μL of acetonitrile as dispersive solvent. The highest amount of SA was extracted with a stir time of 20 min at 300 rpm, followed by centrifugation for 5 min at 4500 rpm. Overall, the findings showed that IL-DLLME is efficient in extracting succinic acid from aqueous environments while adhering to the first-order kinetics.

A microwave-assisted extraction method combined with magnetic ionic liquid-based dispersive liquid-liquid microextraction for the extraction of chloramine-T from fish samples prior to its determination by high-performance liquid chromatography.

In the present work, a combination of microwave-assisted extraction with magnetic ionic liquid-based dispersive liquid-liquid microextraction was developed for the extraction of chloramine-T from fish samples. In this method, the sample was mixed with a hydrochloric acid solution and exposed to microwave irradiations. By doing so, chloramine-T was converted to p-toluenesulfonamide and extracted from the sample into an aqueous phase. Then, a mixture of acetonitrile (as a dispersive solvent) and magnetic ionic liquid (as an extraction solvent) was rapidly injected into the obtained solution. In the following, the magnetic solvent droplets including the extracted analytes were isolated from the aqueous solution in the presence of an external magnetic field and after diluting with acetonitrile injected into high-performance liquid chromatography equipped with a diode array detector. Under the optimum extraction conditions, high extraction recovery (78%), low limits of detection (7.2ng/g) and quantification (23.9ng/g), good repeatability (relative standard deviations ≤5.8 and 6.8% for intra- and inter-day precisions, respectively), and wide linear range (23.9-1000ng/g) were obtained. Finally, various fish samples marketed in Tabriz city (East Azarbaijan, Iran) were analyzed with the suggested method.

Combination of doped amorphous carbon based dispersive solid phase extraction with ionic liquid-based DLLME for the extraction of aromatic amines from leather industries wastewater; Theoretical and experimental insights

In the present investigation, combination of dispersive solid phase extraction with ionic liquid-based dispersive liquid-liquid microextraction was used for the extraction of several aromatic amines from leather industries wastewater. In this approach, initially, N and S doped carbon was used for the adsorption of the analytes from the sample solution and then they were concentrated by the subsequent microextraction step. Determination of the extracted analytes was performed using high performance liquid chromatography-ultraviolet detector. The sorbent contact area with the sample solution was enhanced by performing aspiration/dispersion cycles. In the microextraction procedure, the analytes were enriched into a few microliters of an ionic liquid. Also, interactions between some ionic liquids and the studied aromatic amines were analyzed in the light of performed density-functional theory calculations. The calculated quantum chemical parameters and binding energies for the interactions between ionic liquids of the selected amines showed that the analytes interact powerful with the mentioned ionic liquids and it favorite for the method. The optimized method validation was followed by evaluating several figures of merit and the obtained data showed that limits of detection and quantification, precision (expressed as relative standard deviation), enrichment factor, and extraction recovery were in the ranges of 0.25–0.71 and 0.86–2.4 ng/mL, 3.9–5.2%, 252–312, and 63–78%, respectively. The introduced approach was used in determination of the analytes in the wastewater samples collected from leather manufacturers and p–anisidine, p–chloroaniline, and diethylaniline were determined in them, successfully.

Ultrasound-assisted ionic liquid-based dispersive liquid-liquid microextraction procedure for preconcentration of cobalt and nickel in environmental and biological samples prior to FAAS determination

Ultrasound-assisted ionic liquid-based dispersive liquid-liquid microextraction procedure for preconcentration of cobalt and nickel in environmental and biological samples prior to FAAS determination

Chemometric-Based Optimization of Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction for Separation and Preconcentration of Erythrosine from Real Matrices

In this research paper, a simple and economic ionic liquid-based liquid-liquid microextraction (IL-DLLME) procedure was developed to ensure efficient and rapid separation and preconcentration of erythrosine from cosmetic and food samples. Important parameters such as IL volume, temperature, acetone volume, ultrasonic time and pH that may affect the IL-DLLME procedure have been optimized by central composite design (CCD) based on response surface methodology (RSM). The optimum values of IL volume, temperature, acetone volume, ultrasonic time and pH were determined as 440 µL, 35 oC, 120 µL, 9 min and 4.2, respectively. Using these optimum conditions, some analytical data obtained for erythrosine were listed below. Working range, limit of detection and enrichment factor were 2-400 ng mL-1, 0.65 ng mL-1 and 79, respectively. The relative standard deviation (RSD%) was 2.4% for 50 ng mL-1 of erythrosine. The recovery obtained in the analysis of real samples was in the range of 93.2-108.5%. The analytical data obtained showed that the IL-DLLME procedure was successfully applied to the selected samples

Ionic liquid-based dispersive liquid–liquid microextraction followed by dispersive solid phase extraction coupled with HPLC-DAD for the determination of sulfonylurea herbicides in soymilk samples

The ionic liquid-based dispersive liquid-liquid microextraction followed by dispersive solid phase extraction (IL-DLLME-DSPE) was developed and applied to the extraction of six sulfonylurea herbicides in soymilk samples. High performance liquid chromatography coupled with a diode-array detector was used for the separation and determination of analytes. In this study, [P4 4 4 12] [BF4] was used as an extraction solvent in DLLME and montmorillonite K10 was used as an adsorbent in DSPE. After DLLME and DSPE, the ionic liquid and analytes were adsorbed by montmorillonite K10 and separated from the sample solution. Subsequently, the analytes were desorbed from montmorillonite K10 by acetonitrile. Some parameters, including type and amount of ionic liquid, pH of sample solution, centrifugal speed, and amount of montmorillonite K10, were investigated and optimized. The limits of detection and quantification for analytes were in the range of 1.53–2.32 and 5.10–7.73 µg L−1, respectively. The relative standard deviations for intra-day and inter-day precision were in the range of 1.12–3.59 and 1.99–6.48%, respectively. When the present method was applied to the analysis of real soymilk samples, the recoveries of the analytes were 81.95–118.95%. The results showed that the present method is effective for the extraction of the sulfonylurea herbicides in soymilk samples.

Residual Determination of Multiple Pesticides in Vegetable Samples by LC-MS/MS Coupled with Modified QuEChERS-dSPE Ionic Liquid-Based DLLME Method

As a matter of fact, the Dietary Guidelines of the United States of America recommended the consumption of more fruits and vegetables to support the healthy condition of the body. Unfortunately, these food materials are being accumulated with pesticidal residues due to the continuous miss-management and excessive application of the chemicals during pre and post-agricultural practices, which compels multiple analysis of pesticidal residues to know their concentration levels for the betterment of food security and safety. For that matter, multi-residues of Thiamethoxam, Propamocarb, Carbaryl, Metalaxyl, Baycarb, Thiobencarb, Diazinon, and Dursban pesticides were determined in the samples of lettuce, garlic, ginger, and bell-pepper using modified QuEChERS-dSPE Ionic Liquid-based dispersive liquid-liquid microextraction (DLLME) method coupled with LC-MS/MS instrument and validated (European Union Guideline). Resultantly, the accuracy (87-127%) and precision (0–22%) were mostly within the acceptable range for the former (70-120%) and latter (≤20%). Meanwhile, the limit of detections (0.01-0.28 µg/kg) and limit of quantitations (0.03-0.93 µg/kg) were satisfactory. The concentration range (5–400 µg/kg) of calibration curves for the evaluated linearity were linear with coefficient of regressions greater than 0.99. The matrix effects for all the analyzed samples were very weak and less effective (≤ -86%). The range (1–25%) for the estimated measurement uncertainties were certifiable and acceptable (≤ 50%). Therefore, the sample preparation method prove effective as validated and useful for the multiple determination of pesticides residues in the analyzed vegetable samples, which are presumably safe for consumption against health issues.

Simultaneous preconcentration and determination of zirconium in environmental samples using ultrasound-assisted ionic liquid based dispersive liquid-liquid microextraction combined with spectrophotometry

ABSTRACT The Green, delicate and rapid ultrasound-assisted ionic liquid-based dispersive liquid-liquid microextraction technique was developed to preconcentrate trace quantities of zirconium Zr(IV) ion in real samples prior to spectrophotometric detection. The proposed method uses (1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate) ionic liquid (IL) as an extraction solvent for Zr(IV) ions after the complexation with quinalizarin at pH 5.0. The effect of various analytical parameters has been investigated. The calibration graph was linear in the range of 2.0–400 µg L − 1 and the limit of detection was 0.6 µg L-1. The preconcentration factor was 100. Relative standard deviation (RSD%) at 200 µg L-1 of Zr(IV)for intra-day and inter-day precisionwere 2.0 and 2.7%, respectively (n = 10). Certified reference materialswere used to verify the accuracy.The proposed method was applied to preconcentrate and determine the content of Zr(IV) in real environmental (water, soil and plants) samples with satisfactory results.

A simple and low-cost sample preparation for the effective extraction, purification and enrichment of aflatoxins in wheat by combining with ionic liquid-based dispersive liquid–liquid microextraction

The direct extraction, purification, and enrichment of four aflatoxins (AFs) in wheat were achieved by combining solvent extraction and ionic liquid-based dispersive liquid–liquid microextraction (IL-DLLME). High-performance liquid chromatography coupled with fluorescence detection (HPLC-FD) was applied for the determination of AFs. The feature of the developed technique is that some tedious and time-consuming steps are avoided and the organic solvent consumption is low. The IL-DLLME allows the isolation, purification and enrichment of AFs from the methanol extract using a simple procedure. The effective enrichment was mainly due to the multiple-interaction, including hydrophobic, π-π and hydrogen bonding interactions, between IL and AFs. The parameters affecting the extraction efficiency were thoroughly investigated. This extraction method permits the determination of four AFs with LOD (S/N = 3) and LOQ (S/N = 10) in the range of 0.015–0.20 μg kg−1 and 0.045–0.75 μg kg−1, respectively. The recoveries from four spiked wheat samples ranged from 80.8% to 112.5% with RSDs of 0.8%-4.7% (n = 3), demonstrating the great potential of this proposed procedure for the analysis of AFs in solid samples.

A simple one-step transferred sample preparation for effective purification and extraction of auramine O in bean product by combining air-assisted ionic liquid-based dispersive liquid-liquid microextraction

A one-step transferred sample preparation was developed for the direct purification and extraction of auramine O (AO) in solid bean products by combining air-assisted ionic liquid-based dispersive liquid-liquid microextraction (AA-IL-DLLME). The amount of AO was then determined using high-performance liquid chromatography-ultraviolet/visible detection. Herein, acidified extractant was employed to extract AO from solid samples and served as dispersant of AA-IL-DLLME simultaneously, which simplified the procedure and achieved the one-step transferred operation. The air assistance in IL-DLLME facilitated the rapid and sufficient dispersion of IL in low volume of dispersant, decreasing the consumption of organic solvent and enhancing the extraction efficiency. The high extraction recovery of nearly 90% was ascribed to the possible hydrophobic and π-π interactions between IL and AO. Parameters affecting extraction efficiency, including type and volume of extractant and IL, vortex and centrifugation time etc., were investigated in detail. The limit of detection (LOD, S/N = 3) and limit of quantification (LOQ, S/N = 10) were 0.01 μg g−1 and 0.04 μg g−1, respectively. The relative standard deviations (RSDs, n = 5) for intra-day and inter-day were 2.7%–7.4% and 4.3%–8.1%, respectively. The applicability of the proposed technique was demonstrated by analyzing various bean products with satisfactory relative recoveries of 83.5%–104.8% and RSDs (n = 3) of 1.8%–6.2%.

Vortex-assisted ionic liquid-based dispersive liquid-liquid micro-extraction and spectrofluorometric determination of Rhodamine B in anti-freeze, lipstick, liquid soap, matches and red pencil core

A simple, centrifugeless vortex-assisted ionic liquid-based dispersive liquid-liquid micro-extraction method was developed for spectrofluorometric determination of Rhodamine B dye. Analytical extraction parameters including pH, type and amount of ionic liquid, salt concentration, vortex rate and time were examined and optimized. Matrix effects of potentially interfering ions and dyes were investigated and their tolerable concentrations were determined by applying optimum conditions. Detection limit and preconcentration factor were determined 0.01 μg L-1 and 30, respectively. Dynamic range of the method was linear at RhB concentration range between 0.025 and 1000 μg L-1. Relative standard deviations were 3.9% for the ten replicates measurements of 0.125 μg L-1 Rhodamine B. The method was successfully applied to different samples including anti-freezes, liquid soap, matches, red pencil core and lipsticks. RhB concentrations of liquid and solid samples were determined between 2.05 μg mL-1 and 10.05 μg mL-1 and 307 μg g-1 and 2.75 mg g-1, respectively.

Determination of cadmium in used engine oil, gasoline and diesel by electrothermal atomic absorption spectrometry using magnetic ionic liquid-based dispersive liquid-liquid microextraction

In this study, a sensitive and matrix-effect free analytical method for Cd determination in engine oils and fuel samples by dispersive liquid-liquid microextraction with electrothermal atomic absorption spectrometry has been successfully developed. The extractant solvent used for the microextraction procedure was a magnetic ionic liquid (MIL) (i.e., bis(1-ethyl-3-methylimidazolium) tetrathiocyanatocobaltate (II) [Emim]2[Co(SCN)4]), which presents a paramagnetic property, and allows an easy phase separation using a magnet. In order to eliminate the well-known drawbacks of direct introduction of MIL in the graphite furnace, a back-extraction procedure was performed to transfer the analyte into an aqueous phase. The main experimental factors affecting the extraction of Cd (i.e., amount of sample and MIL, extraction and back-extraction time and concentration and amount of nitric acid) were optimized using a multivariate analysis consisting in two steps: a Plackett-Burman design followed by a circumscribed central composite design. Under optimum conditions (i.e., amount of sample: 6.2 g; amount of MIL: 119 mg; extraction time: 1 min; amount of nitric acid: 200 mg; nitric acid concentration: 1 mol L-1 and back-extraction time: 1 min), the proposed analytical method was validated and successfully used to analyze three real-world samples (i.e., used engine oil, gasoline and diesel). The three samples were spiked at two levels (i.e., 10 and 20 μg kg-1 of Cd for used engine oil and 1 and 3 μg kg-1 of Cd for gasoline and diesel). RSD and recovery values were within the range of 6–11% and 95–110%, respectively.

GREEN VORTEX-ASSISTED IONIC LIQUID-BASED DISPERSIVE LIQUID-LIQUID MICROEXTRACTION FOR ENRICHMENT AND DETERMINATION OF CADMIUM AND LEAD IN WATER, VEGETABLES AND TOBACCO SAMPLES

Objective: An eco-friendly, simple and sensitive vortex-assisted ionic liquid-based dispersive liquid-liquid microextraction method (VA-IL-DLLµE) has been proposed to enrich and determine trace levels of cadmium (Cd2+ ) and lead (Pb2+ ) ions in water, vegetables and tobacco samples, prior to its FAAS determination.
 Methods: The proposed method based on utilization of ionic liquid (IL) (1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate [HMIM][FAP]) as an extraction solvent for both ions after the complexation with 4,5-dihydroxy-3-phenylazo-2,7-naphthalenedisulfonic acid, disodium salt (Chromotrope 2R) at pH 6.5. The impact of different analytical parameters on microextraction efficiency was optimized.
 Results: In the ranges of 1.0–300 and 2.0-400 μg/ml, the calibration graphs were linear. The limits of detection were 0.3 and 0.6 μg/ml for Cd2+ and Pb2+ ions, respectively. The preconcentration factor was 100. The relative standard deviation (RSD %)<3.0%, which indicates the proposed method has high precision.
 Conclusion: The proposed VA-IL-DLLµE method was developed and applied for the estimation of Cd2+ and Pb2+ ion content in various water, vegetables and tobacco samples, and satisfactory results were obtained. The obtained recovery values showed good agreement with the certified values.

A screen-printed electrode modified with silver nanoparticles and carbon nanofibers in a nafion matrix for ionic liquid-based dispersive liquid-liquid microextraction and voltammetric assay of heterocyclic amine 8-MeIQx in food

An electrochemical method is described for the determination of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx) which is a heterocyclic aromatic amine formed in cooked food samples. The method uses a screen-printed carbon nanofiber electrode that is modified with silver nanoparticles (AgNPs) in a Nafion matrix. The surface of the modified electrode was characterized by UV-vis spectrometry, dynamic light scattering, scanning electron microscopy and Raman spectroscopy. The average size of the AgNPs is 14nm. The modified electrode exhibits good properties in terms of reversibility, fast kinetics of electron transfer, and large electroactive area toward the reduction of 8-MeIQx. Differential pulse voltammetry is the most suitable electrochemical technique for quantification of 8-MeIQx, best at a voltage of -0.21V (versus Ag reference electrode). The first derivative serves as the analytical signal that increases linearly in the 0.015-40mgL-1 8-MeIQx concentration range, with a 5μgL-1 detection limit. A dispersive liquid-liquid microextraction procedure assisted via ionic liquid was developed to isolate the analyte from real samples. The whole extraction-preconcentration and voltammetric method allows to determine 30 and 70μgL-1 in (spiked) bouillon cube, meat broth, beer and wine, with recoveries in the 93.6-110.4% range. Graphical abstractSchematic presentation for the analysis of aromatic amine 8-MeIQx, resultant compound from cooking meat. Extracted sample solution was placed onto modified electrode surface thus obtaining voltammetric analytical signal. So, quantification atrelevantlevels can be performed.

Eco-friendlyultrasound-assisted ionic liquid-based dispersive liquid-liquid microextraction of nickel in water, food and tobacco samples prior to FAAS determination

ABSTRACT An environmentally friendly, sensitive, easy and fast ultrasound-assisted ionic liquid-based dispersive liquid-liquid microextraction technique (UA-IL-DLLME) was developed to preconcentrate trace quantities of nickel Ni(II) ion in water, food and tobacco samples prior to detection by FAAS. The proposed technique based on utilisationthe of ionic liquid (IL) (1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate [HMIM][FAP]) as an extraction solvent for Ni(II) ions after the complexation with quinalizarin (Quinz) at pH 6.0. The impact of different analytical parameters on the microextraction efficiency was investigated. In the range of 2.0–300 µg L−1, the calibration graph was linear. Limit of detection and preconcentration factor were 0.6 µg L−1 and 100. Relative standard deviation (RSD%) as precision at 50 and 100 µg L−1 of Ni(II) were 2.4% and 3.6%, respectively (n = 10). The validation of the proposed procedure was verified by a test of two certified reference materials (TMDA-51.3 fortified water, TMDA-53.3 fortified water and SRM spinach leaves 1570A) applying the standard addition method. Finally, the proposed UA-IL-DLLME method was developed and applied to preconcentrate and determine of trace quantities of Ni(II) in real water, food and tobacco samples with satisfactory results.

Determination of Phthalate and Metabolites in Human Urine by Lithium Bis(trifluoromethanesulfonyl)imide-Enhanced Dual Microextraction Method Optimized by Central Composite Design

The traditional optimization of extraction for sample pre-treatment usually involves only the single-factor experimental design to obtain the best conditions of performance. However, in optimization, only employing the single-factor experimental design becomes less frequent as it ignores the interaction among various factors. To identify the effective or critical factors and interactions among them in a sample pre-treatment, the experimental design should be conducted by the design of experiments (DoE). In this study, lithium bis(trifluoromethanesulfonyl)imide (LiNTf2)-enhanced dual microextraction method, a new type of ionic liquid-based dispersive liquid–liquid microextraction (IL-DLLME) was applied for the simultaneous enrichment and extraction of phthalate (PAE) and metabolites showing weak to moderate polarity in human urine. The conditions were optimized by the single-factor experimental design, full factorial design, and central composite design (CCD) based on DoE methodologies. Under optimal conditions, the proposed method performed high recoveries (95.19–98.3%) and low LODs (0.14–0.46 μg L−1) in the range of 2–500 μg L−1 for six PAE and metabolites in human urine. Extending from this study, this method has excellent potential for the enrichment and extraction of chemical compounds ranging from weak to moderate polarity in environmental and biological matrices as well. Besides, for the optimization of sample pre-treatment, DoE is necessary and vital in analytical chemistry and clinical laboratories to obtain the interactions between various factors instead of using only a single-factor experiment.