Liquid-liquid Microextraction Procedure Research Articles

Green liquid supra molecular solvent (SUPRA) phase for fast and selective liquid-liquid micro-extraction of Co2+ ions from aqueous samples

The limitation of Liquid-liquid micro-extraction (LLME) procedures can be the need for the use of a dispersive solvent which should be soluble in both of aqueous and organic phases. In this research, a new method named SUPRA-based LLME, is introduced which uses supra molecular solvent (SUPRA), as an environmentally friendly solvent, for quantitative and selective extraction of Co2+ ions from its aqueous solution via liquid-liquid micro-extraction process. The aqueous immiscible SUPRA phase, composed of vesicles of decanoic acid was synthesized via ex-situ procedure and used as a single liquid phase. In order to make the SUPRA phase selective, N, Nʹ-disalicylidene-3, 4-diaminotoluene (H2dst) was synthesized and completely dissolved in the SUPRA phase. Then the lipophilic and selective prepared liquid sorbent, as liquid SUPRA phase, was used for the facile and selective LLME of Cobalt (II) ions from aqueous samples. Experimental studies showed that there was not any need of dispersing solvent and so liquid SUPRA phase could easily dispersed in the aqueous phase and then separated by centrifugation as the supernatant phase. Then the effects of some important variables on the extraction efficiency were also investigated and optimized. The results showed that under optimal conditions, efficient extraction of Cobalt (II) ions was achieved, about 99 % ± 2.7 (n = 10), in a short time of extraction (10 min), and the linear range of calibration curve was from 500 to 2500 μg L−1 of Cobalt(II) with correlation coefficient of 0.999. Also detection limit and pre-concentration factor were 150 μg L−1 and 35.2, respectively. Although the experimental conditions were optimized for extraction of only Co2+ ions, the selectivity study showed a high tendency of selective liquid SUPRA phase toward extraction of both of Co2+ and Ni2+ ions. The matrix effects on the SUPRA-based LLME of Co2+ ions from matrix samples, factory wastewater and sea-water, were studied and least matrix effects were observed.

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.

Development and Validation of a Sonication-Assisted Dispersive Liquid-Liquid Microextraction Procedure and an HPLC-PDA Method for Quantitative Determination of Zolpidem in Human Plasma and Its Application to Forensic Samples.

The use of z-drugs has increased worldwide since its introduction. Although the prescribing patterns of hypnotics differ among countries, zolpidem is the most widely used z-drug in the world. Zolpidem may be involved in poisoning and deaths. A simple and fast HPLC-PDA method was developed and validated. Zolpidem and the internal standard chloramphenicol were extracted from plasma using a sonication-assisted dispersive liquid-liquid microextraction procedure. The method was validated including selectivity, linearity, precision, accuracy, and recovery. The calibration range (0.15-0.6 µg/mL) covers therapeutic and toxic levels of zolpidem in plasma. The limit of quantification was set at 0.15 µg/mL. Intra- and interday accuracy and precision values were lower than 15% at the concentration levels studied. Excellent recovery results were obtained for all concentrations. The proposed method was successfully applied to ten real postmortem plasma samples. In our series, multiple substances (alcohol and/or other drugs) were detected in most cases of death involving zolpidem. Our analytical method is suitable for routine toxicological analysis.

Method Development and Optimization of Liquid-Liquid Microextraction Based on the Decomposition of Deep Eutectic Solvent for the Determination of Chromium (VI) in Spinach: Assessment of the Greenness Profile Using Eco-scale, AGREE, and AGREEprep

A simple, effective, and ligandless liquid-liquid microextraction (LLME) procedure based on the decomposition of hydrophobic deep eutectic solvents (HDES) was developed for the separation and pre-concentration of chromium (VI) ions in spinach leaves, before the determination by flame atomic absorption spectrophotometry. In the proposed study, the first stage involved the leaching of chromium (VI) from spinach leaves with 0.1 M Na2CO3, and in the second stage, chromium (VI) extract was preconcentrated with the LLME procedure using a DES prepared from the combination of DL-menthol and formic acid as a chelating agent and extraction solvent. The DES decomposed in an aqueous donor phase resulting in the dispersion of menthol and extraction of Cr (VI) ions. Under optimal experimental conditions, the limits of detection (LOD) and quantification (LOQ) were 0.63 and 2.1 µg L−1, respectively. The relative standard deviation (RSD) was less than 7%, and the pre-concentration factor (PF) was found to be 31.25. The accuracy of the present methodology was tested by recovery experiments. The greenness of the developed method was assessed using three quantitative green metrics tools: Analytical Eco-scale, AGREE, and AGREEprep, with only Analytical Eco-scale qualifying the proposed method as green.

Ultrasound- and Vortex-Assisted Dispersive Liquid-Liquid Microextraction of Parabens from Personal Care Products and Urine, Followed by High-Performance Liquid Chromatography.

Parabens, which are p-hydroxybenzoic acid esters, are used as preservatives in personal care products, pharmaceuticals, and food because of their antimicrobial activity. However, they are also classified as suspected endocrine disruptors and carcinogens. In the present study, we aimed to optimize an ultrasound and vortex-assisted dispersive liquid-liquid microextraction (DLLME) procedure for the simultaneous extraction of methyl, ethyl, isopropyl, propyl, isobutyl, and butyl parabens from personal care products and urine. The extraction solvent type, extraction solvent volume, disperser solvent volume, sodium chloride concentration, ultrasonication time, and vortex application time were evaluated to obtain optimum recoveries by ultrasound and vortex-assisted DLLME. Parabens were detected using a validated high performanc-liquid chromatography (HPLC) method with fluorescence detection. Method validation was performed by examining linearity, the limit of detection, limit of quantification, accuracy, and precision. The limits of detection and quantification of the HPLC method were between 0.09-0.18 μg/mL and 0.28-0.54 μg/mL, respectively. Precision was examined as the relative standard deviation, which was 0.22-1.81% and 1.12-2.03% for intra- and interday studies. Recovery percentages were higher than 96.00%. Samples of two paraben-free personal care products and synthetic urine were spiked with the analyses at 0.02 μg/mL and were successfully analyzed using the developed procedure with recovery values higher than 82.00%. The proposed procedure provided quantification of selected parabens at 20 ng/mL in analyzed personal care products and urine matrices with good precision and accuracy.

A green ternary polymeric deep eutectic solvent used in dispersive liquid-liquid microextraction technique for isolation of multiclass pesticides in fruit juice samples

A green dispersive liquid-liquid microextraction procedure based on a ternary polymeric hydrophobic deep eutectic solvent (DES) for monitoring multi-residue pesticides in eleven various fruit juices was developed before Gas Chromatography coupled with micro-Electron Capture Detector (GC-µECD). Six ternary polyethylene glycol (PEG)-based DESs were synthesized, and their extraction efficiency was evaluated. Among these DESs, [thymol]:[polyethylene glycol]:[acetic acid] (1:2:2) showed the highest signal intensity. Moreover, three other binary PEG-based DESs and a non-polymeric DES were also synthesized and compared to the previous DES. The extraction yield obtained by polymeric one was much higher than non-polymeric. Some significant parameters influencing the extraction efficiency including the type and volume of DES (extraction solvent), disperser solvent, pH, and ionic strength were optimized as follows: [Thy]:[PEG]:[HOAc] (1:2:2), 400 µL of DES, ACN as disperser solvent (700 µL), no pH adjustment and no salt addition. The DES was characterized by ATR-FTIR and (1H and 13C) NMR spectroscopy. Under the optimized conditions, the limits of quantification, the linear ranges and extraction recovery were 0.009–0.182 µgL−1 0.003–50.0 µgL−1, 67.9–108.4%, respectively. The enrichment factors were 11–170. Intra-day and inter-day RSDs% were 1.4–5.1% and 2.0–12.6%, respectively. This method was applied for analyzing pesticide residues in eleven fruit juices, and the pre-concentration factor and relative extraction recoveries were in the range of 12–169 and 71–108%, respectively.

Vortex-assisted dispersive liquid-liquid microextraction based on the hydrophobic deep eutectic solvent-based ferrofluid for extraction and detection of myclobutanil.

A vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME) procedure using hydrophobic deep eutectic solvent-based ferrofluid (HDES-FF) as an extractant was established. The developed sample preparation method coupled with high-performance liquid chromatography-diode array detector (HPLC-DAD) was applied to the pretreatment and determination of myclobutanil (MYC) in fruit juice. Hydrophobic deep eutectic solvent, synthesized by n-decanoic acid and DL-menthol, was as a carrier and combined with magnetic nanoparticles (Fe3O4@OA) to form HDES-FF as an extractant with high extraction capacity. The synthesized materials were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Parameters affecting extraction efficiency were optimized using single-factor experiments and Box-Behnken design via response surface methodology (BBD-RSM). Parallel tests were performed three times under the optimal conditions predicted by the model, yielding an actual mean recovery of 94.77% with RSD of 2.7% (n = 3) and an enrichment factor of 41.8 ± 0.98 (mean value ± SD, n = 3). Under the optimal conditions, the linear range was 1.0-100.0µg·mL-1; the limit of detection (LOD) and limit of quantification (LOQ) were 0.25 and 0.80µg·mL-1, respectively. The average spiked recoveries in the samples ranged from 98.2 to 100.5% with intra-day relative standard deviations (RSDs) of 1.2-3.5% (n = 3) and inter-day RSDs of 1.1-3.8% (n = 3). Finally, the method was successfully applied to the determination of MYC antimicrobial agent in different fruit juice samples. The proposed HDES-FF-VA-DLLME/HPLC-DAD method was verified to widely apply to the extraction of triazole fungicides.

Effect of conventional and household water treatment technologies on the removal of pesticide residues in drinking water, Jimma town, Southwestern, Ethiopia.

Water resources have been contaminated by pesticides due to the different activities of human beings. Different studies documented that advanced water treatment systems can eliminate pesticides while conventional and household treatment technologies are not well studied. The main aim of the present study is to determine the effect of conventional and household water treatment technologies on the removal of pesticide residue in drinking water. Water samples were collected from the Gibe River (intake point), from each treatment process, and from the distribution system. To determine the effect of the household water treatment process (solar disinfection and boiling), pesticides were spiked into distilled water and then passed through solar disinfection (SODIS) and boiling. The extraction of samples was conducted by following a low-density-based dispersive liquid-liquid microextraction procedure. The result of the study revealed that almost all studied pesticides except o´p-DDT were detected in water samples. Most pesticides that were detected in water samples from our study areas exceeded the maximum residue limits (MRLs), except for p,p'-DDE. The percent reduction of pesticide residue after post-chlorination by conventional water treatment ranges from 11.7% (from 70.83 μg/L to 62.54 μg/L) for p´p-DDD to 97.29% (5510.1μg/L to 149.5μg/L) for Dimethachlor, and the percent reduction of pesticide residue by SODIS and boiling ranges from 2.31% (o´p-DDT) to 54.45% (Cypermethrin) and 27.13% (γ-Chlordane) to 38.9% (p´p-DDE) respectively. This indicates that treatment technologies are important for the reduction of pesticides in water. Since studied pesticides are persistent and the resides were exceed MRL (have a health impact), monitoring of pesticides in treatment plant units is necessary and treatment technology improvement is important to allow further removal of pesticides.

Simple method for Cr(VI) determination by liquid-liquid microextraction combined with total reflection X-ray fluorescence spectrometry: Application to water samples and industrial extracts

In the present contribution, a simple and inexpensive method for the determination of hexavalent chromium in aqueous solutions was developed. The analytical methodology consists of the combined use of a low cost Cr(VI) isolation procedure followed by the analysis using total reflection X-ray spectrometry (TXRF). The liquid-liquid microextraction procedure (LLME) used is based on the formation of an ion-pair between the cationic part of the surfactant cetyltrimethylammonium bromide (CTAB) and the corresponding anionic Cr(VI) species, which is extracted in few microliters of chloroform. TXRF analysis can be performed directly by deposition of 15 μL of the preconcentrated sample on a sample carrier, without any additional sample treatment.Experimental parameters affecting Cr(VI) extraction and TXRF analysis were studied in detail. Under optimum conditions, a good linearity was obtained in the range of 5–5000 μg/L with a limit of detection for hexavalent chromium of 0.9 μg/L. This fact opens the possibility of Cr determination in aqueous samples characterized by different concentration levels. The methodology was successfully applied for the determination of Cr(VI) species in different type of water matrices (tap, well, river and sea water) as well as industrial aqueous samples including in industrial waste water from a galvanic industry and aqueous clinker extracts. For comparison purposes, the determination of Cr(VI) in industrial samples was also carried out by using the colorimetric method EPA Method 7196.

Surfactant-enhanced air-agitation liquid-liquid microextraction of polycyclic aromatic hydrocarbons from edible oil using magnetic deep eutectic solvent prior to HPLC determination.

Herein, an air-agitation liquid-liquid microextraction procedure was developed for the extraction of several polycyclic aromatic hydrocarbons from edible oil samples. In this study, the extraction procedure was achieved using a new magnetic deep eutectic solvent as the extraction solvent, in which there was no need for centrifugation. To enhance the rate of extraction of the analytes from the samples, the method was promoted by the use of surfactant addition. The extracted analytes were determined by high-performance liquid chromatography with a diode array detector. The influence of various parameters on the extraction efficiency was studied by response surface methodology using a central composite design. Under optimal conditions, linear calibration curves for the target analytes were achieved in the range of 0.43-250 ng g-1. The limits of detection and quantification were in the ranges of 0.04-0.13 and 0.13-0.43 ng g-1, respectively. The repeatability of the method in terms of intra- and inter-day precision was ≤4.7% and ≤6.7%, respectively. The extraction recovery of the method ranged from 75 to 88%. The obtained results show that the proposed method is efficient for the analysis of the target analytes in various oil samples without obvious matrix effects. Pyrene was found in olive oil at a concentration of 42 ng g-1.

Development of a pH-induced dispersive solid-phase extraction method using folic acid combined with dispersive liquid-liquid microextraction: application in the extraction of Cu(II) and Pb(II) ions from water and fruit juice samples.

In this study, a new pH-induced dispersive solid-phase extraction method using folic acid has been proposed for the extraction of Cu(II) and Pb(II) ions from water and fruit juice samples. For this purpose, at first, a specified amount of folic acid was dissolved in the sample solution containing the studied ions at pH 8.5. Then, by decreasing pH of the solution, solubility of folic acid reduced and its fine particles containing the analytes were produced. They were separated and dissolved in dimethylformamide. For more preconcentration, the developed procedure was combined with a dispersive liquid-liquid microextraction procedure. Finally, the extracted and enriched analytes were determined by flame atomic absorption spectrometry. The effect of important parameters on the extraction efficiency of the method such as pH, folic acid amount, the amount of complexing agent, dimethylformamide volume, ionic strength, and centrifugation conditions were studied. Under optimized conditions, the developed method showed linear ranges of 0.20-40 and 0.25-40µgL-1 for Pb(II) and Cu(II) ions, respectively. Limits of detection of Pb(II) and Cu(II) were 0.07 and 0.08µgL-1, respectively. The relative standard deviations (intra- and inter-day precisions) were between 3.8 and 5.4%. Accuracy of the proposed method was studied by determination of the analytes concentrations in a certified reference material; SPS-WW2 Batch 108. Efficiency of the proposed procedure was evaluated by analyzing Pb(II) and Cu(II) ions in various water and fruit juice samples.

Microextraction of ampicillin from bovine milk using ionic liquids and deep eutectic solvents prior to its chromatographic determination with ultraviolet and tandem mass spectrometry detection

Liquid-liquid microextraction procedures using ionic liquid (IL) and deep eutectic solvent (DES) as the new extractants for isolation of β-lactam antibiotic ampicillin (AMP) from milk samples were developed. In this purpose IL: 1-butyl-3-methylimidazolium hexafluorophosphate and DES: choline chloride-thymol (1:2) were used as the extraction medium. These green solvents are characterized by favorable solvating properties for a range of compounds. Ionic liquid was used as extractant in dispersive liquid-liquid microextraction (DLLME) connected with acetonitrile as disperser solvent while deep eutectic solvent was applied for liquid-liquid microextraction (LLME). The isolation parameters of ampicillin, namely, amount of extraction solvents, pH of milk sample, shaking and centrifugation time were optimized. The extracts were analyzed followed by liquid chromatographic method with ultraviolet (HPLC-UV) and tandem mass spectrometry (LC-MS/MS) system for DLLME and LLME isolation procedures, respectively. The calibration curves were linear in the analyte concentration range of 1 . 10−7 mol L−1 (36.1 µg kg−1) – 1 . 10−4 mol L−1 (36127.0 µg kg−1) for IL-DLLME-HPLC-UV technique and 1 . 10−8 mol L−1 (3.6 µg kg−1) – 1 . 10−4 mol L−1 (36127.0 µg kg−1) for DES-LLME-LC-MS/MS method. The elaborated procedures were applied for the determination of ampicillin in the different milk samples.

Experimental design of magnetic ionic liquid ultrasound-assisted dispersive liquid-liquid microextraction for the determination of 5-HMF in honey samples

A green, sensitive, and accurate ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) procedure using a magnetic ionic liquid (magnetic-IL) was optimized for the preconcentration and extraction of 5-hydroxymethylfurfural (5-HMF) in honey samples collected from different regions of Turkey prior to analysis by UV–VIS spectrophotometer. A multivariate optimization strategy was employed to optimize microextraction factors (pH, [C8mim]FeCl4 magnetic-IL amount, ultrasound time, dispersing agent volume) affecting the magnetic-IL UA-DLLME. Since the separation of the phases was achieved with a neodymium magnet, centrifugation step was not necessary. Under optimal experimental conditions, linear range of 3–600 µg L−1, limit detection of 1.0 µg L−1 and an enrichment factor of 175 were obtained. The magnetic-IL UA-DLLME procedure was successfully applied for the analysis of 5-HMF in the honey samples, and the extraction recovery were in the range of 92–103%. To evaluate the precision of the magnetic-IL UA-DLLME procedure, relative standard deviations from the inter-day assay and intra-day assay ranged from 3.9% to 5.1% and 3.3–4.2%, respectively. This study reports the first application of magnetic-IL with the UA-DLLME technique based on multivariate optimization for the determination of 5-HMF in different honey samples.

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

Vortex-assisted liquid-liquid microextraction combined with liquid chromatography tandem mass spectrometry for simultaneous determination of cardiovascular drugs in human plasma

Hypertension and dyslipidemias are among the main risk factors for the development of cardiovascular diseases, which are responsible for the death of approximately 17 million people each year. There are several drugs available for the treatment of these diseases. Therefore, methods for the simultaneous analysis of several of these drugs are useful in a wide range of situations. In this context, this study aimed to develop a modern method for the simultaneous determination of eight cardiovascular drugs in human plasma. A vortex-assisted liquid-liquid microextraction (VALLME) procedure, combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. Mass spectrometry conditions, chromatographic separation, and sample preparation were optimized. For VALLME optimization, pH, sodium chloride concentration, volume of buffer solution, extraction solvent (type and volume), and vortex stirring time were evaluated. The method proved to be simple, fast, and environmentally friendly since low volumes of organic solvent were employed. Furthermore, the VALLME procedure required small sample volume, which is desirable when large volumes are scarce. Suitable recoveries and lower limits of quantification were achieved with a chromatographic run of only 8 min. The method was validated, showing to be selective, precise, and accurate. Furthermore, the analytical curves were well fitted to the selected models and the matrix effect did not affect method reliability. The developed method was successfully applied for the analysis of plasma samples obtained from volunteers attending a hospital service.

DES-based vortex-assisted liquid-liquid microextraction procedure developed for the determination of paraben preservatives in mouthwashes

A green deep eutectic solvent-based vortex-assisted liquid–liquid microextraction (DES-VALLME) procedure for the determination of parabens in mouthwashes was developed. Deep eutectic solvents formed by combining DL-menthol and decanoic acid in different mol ratios were prepared, the highest extraction recovery was obtained with DES consisting of 4:1 M ratio, and this DES was used as an extraction solvent for paraben determination in mouthwashes. The effect of parameters such as solution pH, mol ratio of DES composition, DES volume, vortex and centrifugation time and sample volume were examined. Optimum working conditions of the study; 400 µL DES, 3 min. vortex time, 5 min. centrifugation time, 5 mL sample volume were determined. The detection limit was in the range of 4.6–6.1 µg L−1, while the RSDs values were in the range of 0.70–1.41% in intraday and 1.27–2.41% in interday. The method in the study was successfully applied for the determination of methyl, ethyl, propyl and butyl paraben in 10 different mouthwashes obtained from cosmetic stores..

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

Rapid analysis of chromium (III, VI) in water and wastewater samples based on Task-specific ionic liquid by the ultra-assisted dispersive ionic liquid-liquid microextraction

In this research, 2-mercapto-1-methylimidazole a novel Task-specific ionic liquid (C4H6N2S; HS-CH3-IM) was used with a new approach for speciation of Cr (III, VI) from water samples by ultra-assisted dispersive ionic liquid-liquid microextraction procedure (USA-D-ILLME). Due to the procedure, 100 mg of HS-CH3-IM and 0.2 mL of acetone were mixed and injected into 10 mL of water or standard Cr (III) and Cr (VI) solution in the conical tube. After stirring for 5 min, the Cr (VI) and Cr (III) were extracted with a positive and negative charge of the thiol group (HS2+, HS-) in pH 2 or 8 and pH 5, respectively. The Cr (III, VI) loaded on the HS-CH3-IM was back-extracted in a liquid solution. Finally, the concentration of the Cr (III, VI) ions in a remained solution were measured with ET-AAS . The total chromium was determined in water samples by summarizing the Cr (VI) and Cr (III) contents. All parameters such as the amount of HS-CH3-IM, the sample volume, pH, and the shaking/centrifuging time were optimized. Under the optimal conditions, good linear range (LR), LOD, and enrichment factor (EF) were obtained 0.05–1.7 μg L−1, 15 ng L−1, and 19.82 respectively (RSD% < 1.45).

Riboflavin as a green sorbent in dispersive micro-solid-phase extraction of several pesticides from fruit juices combined with dispersive liquid-liquid microextraction.

A vortex-assisted dispersive micro-solid-phase extraction procedure using a new and green sorbent was developed as a simple, fast, and efficient sample preparation method for the extracting five pesticides in several fruit juice samples. In this study, for the first time, riboflavin was used as an efficient sorbent. A few milligrams of riboflavin was directly added into the aqueous solution containing the analytes to adsorb them. After adsorption the analytes, they were desorbed and more concentrated by a dispersive liquid-liquid microextraction procedure. The influence of several effective parameters such as amount of riboflavin, pH, vortex time, eluent nature and volume, and extraction solvent type and volume on the extraction efficiency was investigated. In optimal conditions, linear ranges of the calibration curves were broad. The limits of detection and quantification were attained in the ranges of 0.56-1.5 and 1.9-0.52ng mL-1 , respectively. The proposed method demonstrated to be suitable for concurrent extraction of the studied pesticides in various fruit juice samples with high enrichment factors (320-360) and precision (relative standard deviation ≤7.8% for intra- [n=6] and interday [n=4] precisions at a concentration of 25ng mL-1 of each pesticide).

GC–MS determination of malondialdehyde, acrolein, and 4-hydroxy-2-nonenal by ultrasound-assisted dispersive liquid-liquid microextraction in beverages

A new, fast, simple, and effective ultrasound-assisted dispersive liquid-liquid microextraction procedure (UA-DLLME) for the gas chromatography-mass spectrometry (GC–MS) determination of malondialdehyde, acrolein, and 4-hydroxy-2-nonenal in beverages was successfully developed. 2,4-Dinitrophenylhydrazine derivatization was performed during extraction. An asymmetrical 3541//18 screening design and a central composite surface response design were used to investigate the influence of the most critical factors during the extraction process (ultrasound time and temperature, extraction and disperser solvents volumes, salt addition, and derivatization reagent concentration). According to FDA guidelines, the method was validated, achieving good linearities with r2 ≥ 0.9982, recoveries between 94.0 and 102.4%, and reproducibility with RSD lower than 4.5%. The method was applied to simultaneously determine the compounds in 60 different beverage samples, including beer, coffee, black tea, and fruit juices. The presence of secondary lipid oxidation products is demonstrated in beverages with a strong roasting process or oxidation.