Type Of Extraction Solvent Research Articles

Rapid Ultrasound-Assisted Emulsification Microextraction Combined with COU-2 Dispersive Micro-solid Phase Extraction for the Determination of Azole Antifungals in Milk Samples by HPLC-DAD

A rapid, simple, and efficient method using ultrasound-assisted emulsification microextraction combined with dispersive micro-solid phase extraction (USAE-D-µ-SPE) was developed for detection and quantification of three azole antifungals in milk samples by high-performance liquid chromatography diode array detector. In this study, mesoporous carbon, COU-2, was used as sorbent in USAE-D-µ-SPE for the extraction and preconcentration of analytes. Several important experimental parameters, including type of deproteinized solvents, desorption time, type of extraction solvents, volume of extraction solvent, extraction time, emulsification time, sample pH, salt addition, and mass of COU-2 sorbent, were optimized using spiked milk samples. Under the optimum extraction and detection conditions, three azole antifungals, namely ketoconazole, clotrimazole, and miconazole, were determined within 20 min, with good linearity of matrix-matched calibration in the range of 0.5–5000.0 µg L−1 with coefficient of determination, r 2 ≥ 0.9943. The method showed limits of detection and limits of quantification of all analytes in the range of 0.15–3.0 and 0.5–10.0 µg L−1, respectively. Good repeatability with RSDs <15% (n = 3) and satisfactory relative recoveries (83.3–111.1%) were obtained for spiked azole antifungal drugs in milk. The results reveal that the developed USAE-D-µ-SPE method was a simple, rapid, efficient, environmentally friendly, and practicable method for the determination of azole antifungals in milk samples.

Simultaneous determination of deltamethrin, permethrin and malathion in stored wheat samples using continuous sample drop flow microextraction followed by HPLC–UV

Wheat (Triticum aestivum) is an important staple food worldwide used for the manufacture of flour-derived foodstuffs such as bread and noodles. The purpose of this study was to investigate common pesticides in stored wheat at Kermanshah province’s silos in Iran. Continuous sample drop flow microextraction coupled with high-performance liquid chromatography–ultraviolet (HPLC–UV) detection was applied for this purpose. In this technique, a few microliter of organic solvent is transferred to the bottom of a conical test tube and the aqueous solution transforms in form fine droplets while passing through the organic solvent. After extraction, 20 μL of organic solvent containing target analytes was injected into the HPLC–UV. The extraction conditions (including type and volume of extraction solvent, sample solution flow rate, sample solution volume, pH and salt addition) were varied to achieve optimized performance. Under the optimum conditions, the calibration graphs are linear in the range of 0.5–1000 µg kg−1 and limit of detections (LODs) are in the range of 0.2–0.5 µg kg−1. Repeatability (intra-day) and reproducibility (inter-day) of method based on seven replicate measurements of 100 µg kg−1 of target pesticides were in the range of 3.2–5.1% and 4.7–7.2%, respectively. Three out of 36 wheat grain samples contained permethrin exceeding safety levels, but the levels of the other two pesticides in all samples were below the maximum residue levels based on Europe standard level.

A green cloud-point microextraction method for spectrophotometric determination of Ni(II) ions with 1-[(5-benzyl-1,3-thiazol-2-yl)diazenyl]naphthalene-2-ol

In this paper the efficiency of cloud point microextraction method has been confirmed by the preconcentration and spectrophotometric determination of nickel(II) ions with a new organic reagent 1-[(5-benzyl-1,3-thiazol-2-yl)diazenyl]naphthalene-2-ol. The influence of several factors (the acidity of the media, the time of the reaction and heating, the type of extraction solvent used) on the interactions between Ni(II) and the azo dye was checked. Optimal conditions for carrying out the complexation reaction between the reagent and Ni(II) were established (absorbance maximum wavelength λmax=605nm, time of heating the solution theat.=10min, the acidity pHopt.=5.5). Qualitative characteristics of the formed complex were calculated (ε610=1.56×104Lmol−1cm−1, lgβ=6.18). Two spectrophotometric methods of nickel(II) determination with the application of conventional liquid-liquid extraction and cloud-point microextraction were developed, and their main analytical characteristics were compared. The elaborated extraction technique with the application of cloud-point extraction and liquid-liquid microextraction provides significantly better performance characteristics for nickel determination (LOD=3.9μgL−1, LOQ=11.8μgL−1), and instead of 25mL of toxic toluene, only 200μL of ethylene glycol was used. The new method of Ni(II) determination was tested on model solutions and real samples.

Solid-phase extraction assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet to determine sildenafil and its analogues in dietary supplements.

A novel analytical method for the simultaneous determination of the concentration of sildenafil and its five analogues in dietary supplements using solid-phase extraction assisted reversed-phase dispersive liquid-liquid microextraction based on solidification of floating organic droplet combined with ion-pairing liquid chromatography with an ultraviolet detector was developed. Parameters that affect extraction efficiency were systematically investigated, including the type of solid-phase extraction cartridge, pH of the extraction environment, and the type and volume of extraction and dispersive solvent. The method linearity was in the range of 5.0-100ng/mL for sildenafil, homosildenafil, udenafil, benzylsildenafil, and thiosildenafil and 10-100ng/mL for acetildenafil. The coefficients of determination were ≥0.996 for all regression curves. The sensitivity values expressed as limit of detection were between 2.5 and 7.5ng/mL. Furthermore, intraday and interday precisions expressed as relative standard deviations were less than 5.7 and 9.9%, respectively. The proposed method was successfully applied to the analysis of sildenafil and its five analogues in complex dietary supplements.

Development and Validation of a GC-MS Method for the Analysis of Homogentisic Acid in Strawberry Tree (Arbutus unedo L.) Honey.

To confirm the botanical origin of strawberry tree (Arbutus unedo L.) honey, a liquid-liquid extraction followed by GC-MS method was developed for the quantitative determination of homogentisic acid (HGA), the main phenolic compound in this honey. Different parameters affecting extraction, such as the type and volume of extraction solvents, pH of the solution, and amount of salt, were optimized. The method showed good linearity (r2 = 0.9990) over the tested concentration range (50-500 mg/kg) and a low LOD (0.3 mg/kg). Precision expressed as RSD was <7%. The average accuracy was 95%. The optimized method was applied for determining the HGA content in strawberry tree honey samples from Croatia. The HGA content in analyzed samples (n = 7) ranged from 245.1 to 485.9 mg/kg. The proposed method provided reliable performance and can be easily implemented for the routine monitoring of HGA in strawberry tree honey in order to assure honey QC.

A Novel Dispersive Nanomagnetic Particle Solid-Phase Extraction Method to Determine Aflatoxins in Nut and Cereal Samples

The application of a simple, fast, and cheap sample pre-concentration technique based on the dispersive magnetic Fe3O4 nanoparticle solid-phase extraction has been developed for extraction and determination of aflatoxins B1, B2, G1, and G2 in nut and cereals. Aflatoxins were extracted from samples with a mixture of methanol–water 8:2 (v/v) and then by magnetic Fe3O4 nanoparticles and a 500 μL of chloroform; pre-concentration and cleanup of the analytes simultaneously were done. HPLC with fluorescence detector and electrochemical post-column derivatization has been used for aflatoxin determination. The main parameters affecting the extraction efficiency, such as type and volume of extraction solvent, the volume of water, and sample volume, were investigated and optimized to achieve the best extraction efficiency. The LODs and LOQs of the proposed method for the AFs were determined, which LODs were 0.35 and 0.06 μg/kg, and LOQs were 1 and 0.2 μg/kg, for aflatoxin groups B and G, respectively. Acceptable recoveries were achieved (76.0–112.7%), and the low limits of detection (LOD <0.35 and 0.06 μg/kg), with proper precision (RSD <15%), were obtained. Therefore, the validated method represents simple and low-cost substitute to the conventional method and is suitable for screening of contamination in food samples.

Ionic-liquid-functionalized zinc oxide nanoparticles for the solid-phase extraction of triazine herbicides in corn prior to high-performance liquid chromatography analysis.

Zinc oxide nanoparticles have recently been used as effective adsorbent materials for sample pretreatment in analytical chemistry because of their excellent properties, such as high specific surface area, high effective porosity, non-toxicity, and ease of fabrication. In this study, the zinc oxide nanoparticles functionalized by an ionic liquid, 1-carboxyethyl-3-methylimidazolium chloride, were fabricated and used as the adsorbent for the solid phase extraction of five triazine herbicides in corn for the first time. High-performance liquid chromatography was employed for the determination of these triazine herbicides. Several experimental parameters affecting the extraction efficiency were investigated, including the volume of extraction solvent, the extraction time, the type of extraction solvent and elution solvent, the amount of absorbent, and the volume of elution solvent. By using the proposed method, low limits of detection and quantification for all the five triazine herbicides were obtained between 0.71-1.08 and 2.67-3.64ng/g, respectively. Recoveries of the proposed method range from 89.05 to 100.33% with intra- and inter-day relative standard deviations lower than 8.45%. The calibration curves are linear in the concentration range of 0.005-1.00μg/g with the correlation coefficient higher than 0.9954.

Vortex-Assisted Inverted Dispersive Liquid-Liquid Microextraction of Naproxen from Human Plasma and Its Determination by High-Performance Liquid Chromatography

Extraction and determination of naproxen from human plasma were performed using Vortex-Assisted Inverted Dispersive Liquid-Liquid MicroExtraction (VA−IDLLME) and High-Performance Liquid Chromatography (HPLC). The parameters affecting extraction recovery such as type and volume of extraction and disperser solvents, pH of sample solution, stirring rate, extraction time and salt addition were optimized. Optimal extraction conditions were: 100 µL dodecane as the extraction solvent, 350 µL methanol as disperser solvent, pH of sample = 5, stirring rate: 500 rpm, with no effect of extraction time and no addition of NaCl to the sample solution. Under the optimal conditions a linear range of 1.0–1000.0 ng/mL(R2 = 0.9993) was obtained. Limit of detection, the extraction recovery, and preconcentration factor were 0.32 ng/mL, 87% and 108 respectively.

Determination of organotin compounds in sediment samples by dispersive liquid-liquid microextraction followed by gas chromatography – Pulsed flame photometric detection (DLLME-GC-PFPD)

Dispersive liquid-liquid microextraction (DLLME) was evaluated for the simultaneous determination of butyl-, phenyl- and octyltin compounds in sediment samples. The most significant factors in DLLME procedure were type and volume of extraction and disperser solvents, and the optimal conditions were reached when 413 and 34μL of methanol and tetrachloroethylene, respectively, were used. Under optimal conditions, the limit of detection and the relative standard deviation ranged between 0.3 and 1.0ngL−1 and 2–6%, respectively. The developed method was validated for the analysis of a certified reference material and spiked seawater and marine sediment samples, with satisfactory results. Finally, harbor sediment samples collected from the Chilean coastal region were analyzed to demonstrate the applicability of the developed method in the determination of organotin compounds in the environment.

Dispersive liquid–liquid microextraction as an effective preanalytical step for the determination of estradiol in human urine

In this work, a fast and effective dispersive liquid-liquid microextraction was developed for the isolation and preconcentration of free 17β-estradiol, the main human estrogen, from real human urine samples. To optimize the extraction technique, few important parameters such as type and volume of extraction and dispersive solvents, centrifugation conditions, effect of salt addition, and extraction time were studied. Optimal conditions were obtained when injecting 600μL mixture of tetrachloromethane as extraction solvent and ethanol as dispersive solvent (1:5, v/v) into 2mL of urine containing 8% NaCl and following centrifugation at 10000rpm, thus reaching enrichment factor 28 and extraction recovery 98% for estradiol. Procedure was evaluated by means of high-performance liquid chromatography with UV detection (λ=280nm) using a C-18 column and methanol/water (60:40, v/v) as the mobile phase. The method was linear within the concentration range 1.0-250.0mg/L (r=0.9997) and provided a limit of detection of 0.25mg/L. The proposed method was applied to the determination of free estradiol in real human pregnancy urine.

Dynamic microwave assisted extraction coupled with matrix solid phase dispersion for the determination of chlorfenapyr and abamectin in rice by LC-MS/MS

Chlorfenapyr and abamectin are two insecticides used commonly in rice-planting to control insects and mites. The residue remained in rice present potential health hazard to consumers. To realize the accurate determination of chlorfenapyr and abamectin in rice samples, a method based on dynamic microwave assisted extraction (DMAE) coupled with matrix solid phase dispersion (MSPD) was established and validated. In the proposed method, microwave energy was introduced into the elution process of MSPD and therefore improved the extraction efficiency. Different parameters affecting the extraction efficiency were studied and optimized, including type of dispersing sorbent, ratio of dispersing sorbent to sample, type of clean-up sorbents, microwave power, extraction solvent, volumes and flow rate of extraction solvent. Under optimal conditions, the interference in rice extract were removed effectively, moreover, the extraction and clean-up were combined in a single step and 15 samples were treated simultaneously with in 4min. Low limits of detection (0.8ng g−1) for chlorfenapyr and abamectin were obtained. The RSDs of intra- and inter-day were in the range of 2.6 to 8.1%. The recoveries of chlorfenapyr and abamectin from rice samples at spiking levels of 5, 50 and 100ng g−1 were 92.1–96.5% and 88.6–91.0%, respectively. Finally, the proposed method was successfully applied to analyze chlorfenapyr and abamectin in six rice samples, and satisfactory results were obtained.

New procedure for the examination of the degradation of volatile organonitrogen compounds during the treatment of industrial effluents.

We present a new procedure for the determination of 32 volatile organonitrogen compounds in samples of industrial effluents with a complex matrix. The procedure, based on dispersive liquid-liquid microextraction followed by gas chromatography with nitrogen-phosphorus and mass spectrometric detection, was optimized and validated. Optimization of the extraction included the type of extraction and disperser solvent, disperser solvent volume, pH, salting out effect, extraction, and centrifugation time. The procedure based on nitrogen-phosphorus detection was found to be superior, having lower limits of detection (0.0067-2.29 μg/mL) and quantitation as well as a wider linear range. The developed procedure was applied to the determination of content of volatile organonitrogen compounds in samples of raw effluents from the production of bitumens in which 13 compounds were identified at concentrations ranging from 0.15 to 10.86 μg/mL and in samples of effluents treated by various chemical methods.

An alternative perspective of hollow fiber-mediated extraction: Bundled hollow fiber array-liquid-phase microextraction with sonication-assisted desorption and liquid chromatography–tandem mass spectrometry for determination of estrogens in aqueous matrices

A bundled hollow fiber array (BHF)-liquid-phase microextraction (LPME) approach has been developed for the ultra-high performance liquid chromatography tandem mass spectrometric determination of estrone, 17β-estradiol, estriol, and 17α-ethinylestradiol. The BHF was dipped in n-octanol to impregnate only the wall pores of the hollow fibers without deliberate loading of extractant solvent in the lumens, before placing it in the sample for extraction. Parameters influencing extraction efficiency, such as number of bundled hollow fibers, type of extraction and desorption solvent, agitation mode, extraction temperature and duration, and the salting out effect were examined. Under the most favourable experimental conditions, the enrichment factors were between 77 and 137-fold for the target compounds. The developed method offered high sensitivity and reproducibility. Low limits of detection and limits of quantification were achieved, i.e., between 0.251 and 0.440ng/L, and 0.995 and 1.82ng/L, respectively. Good intra and inter-day precision were obtained with relative standard deviations (RSDs) of less than 9%. BHF-LPME provided a new perspective on using membrane solvent-supported hollow fiber-mediated LPME. Raman spectroscopy was also introduced in this study to reaffirm that the polypropylene BHF did not play any role in the extraction; only the solvent was responsible.

A Robust Method for Routine Analysis of Perfluorooctane Sulfonate (PFOS) and Perfluorohexane Sulfonate (PFHxS) in Various Edible Crop Matrices

A reliable, sensitive, and efficient method was developed for routine analysis of perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) in various edible crop matrices including cereal (grain), root vegetable (carrot), leafy vegetable (lettuce), and melon vegetable (pumpkin). The target analytes were extracted by ion-pair approach followed by solid-phase extraction clean-up and HPLC-MS/MS. The type of extraction solvent, clean-up cartridge, and the usage of Supelclean graphitized carbon were evaluated to reach an optimized pretreatment procedure. The matrix-matched standard calibrations relative to the isotope-labeled internal standard were used in the developed method to obtain more reliable quantitative results. The average recoveries at four spiked levels (0.5, 10, 25, 50 ng/g) in the diverse matrices ranged from 70.9 to 114.6% with relative standard deviations (RSD) lower than 11.5%. The matrix-dependent method detection limits using the common equipment (HPLC-MS/MS) were between 0.020 and 0.140 ng/g (dw), equivalent to the 3–130 pg/g (fw), corresponding to the sensitivity of superior equipment (e.g., UPLC-MS/MS and HPLC-QTOF-HRMS). Furthermore, the developed method was conferred with the practicality through determination of the analytes in actual crops sampled from several farms in China’s Pearl River Delta.

Binary-solvent-based ionic-liquid-assisted surfactant-enhanced emulsification microextraction for the determination of four fungicides in apple juice and apple vinegar.

A binary-solvent-based ionic-liquid-assisted surfactant-enhanced emulsification microextraction method was developed for the separation/preconcentration and determination of four fungicides (pyrimethanil, fludioxonil, cyprodynil, pyraclostrobin) in apple juice and apple vinegar. A nonchlorinated solvent amyl acetate, which has a lower density than water, was used as the extraction solvent, and an ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate, which has a high density and low toxicity, was used as a secondary solvent mixed with the extraction solvent. After centrifugation, the binary solvent drop with a relatively high density was deposited on the bottom of the tube. Some parameters influencing the extraction efficiency of analytes such as type of extraction solvent, ratio of ionic liquid, volume of mixed solvent, type and concentration of surfactant, sample pH, NaCl concentration, and vortex time were investigated and optimized. Under the optimized conditions, the proposed method provided a good linearity in the range of 5-200 μg/L. The limits of quantification of the method were in the range of 2-5 μg/L. The relative standard deviations for interday assays were 1.7-11.9%. The method was applied to the determination of pyrimethanil, fludioxonil, cyprodynil, and pyraclostrobin in apple juice and apple vinegar samples, and the accuracy was evaluated through recovery experiments.

Determination of trace amount of cadmium using dispersive liquid-liquid microextraction-slotted quartz tube-flame atomic absorption spectrometry

This study was performed to develop a sensitive analytical method for the determination of cadmium by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS) after dispersive liquid-liquid microextraction (DLLME). The parameters affecting the cadmium complex formation and its extraction output were optimized to obtain high extraction efficiency. These included the pH and amount of the buffer solution, and the concentration of the ligand. The DLLME method was comprehensively optimized based on the type and amount of extraction solvent, dispersive solvent and salt. The type and period of mixing needed for a more effective extraction was also investigated. In order to further improve the sensitivity for the determination of cadmium, the flame atomic absorption spectrometry was fitted with a slotted quartz tube to increase the residence time of cadmium atoms in the pathway of incident light from a hollow cathode lamp. The limits of detection and quantitation (LOD and LOQ) for the FAAS were found to be 42 and 140μgL−1, respectively. Under the optimum conditions, LOD and LOQ of the FAAS after DLLME were calculated as 1.3 and 4.4μgL−1, respectively. Combining both optimized parameters of the DLLME and SQT-FAAS gave 0.5 and 1.5μgL−1 as LOD and LOQ, respectively. Accuracy of the method was also checked using a wastewater certified reference material (EU-L-2), and the result was in good agreement with the certified value.

Ionic-Liquid-Based Infrared-Assisted Extraction (IL-IRAE) Coupled with HPLC–MS: a Green and Convenient Tool for Determination of TCMs

Infrared radiation, one form of electromagnetic wave, has potential value due to its heating effect, but has become a matter of grave concern in recent years. We describe herein ionic-liquid-based infrared-assisted extraction (IL-IRAE) coupled with high-performance liquid chromatography (HPLC)–mass spectrometry (MS) as a green and convenient method for simultaneous determination of three alkaloids in Lycoris radiata, a traditional Chinese medicine (TCM). Extraction parameters including the type and concentration of IL, extraction solvent, liquid/solid ratio, extraction time, and irradiation power were optimized via orthogonal design and analysis of variance (ANOVA). Chromatography–mass spectrometry was performed in positive ion mode on a TSK gel C18 column (150 mm × 4.6 mm id, 5-µm particle size) with less than 5-min separation. Evaluation of the method showed good results with analytical recovery ranging from 100.66 to 103.90 %. The extraction efficiency of IL-IRAE was proved to be increased by 25 % compared with conventional heat reflux extraction (HRE), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE) methods under the operational parameters investigated in the study, indicating that the developed IL-IRAE method is environmentally friendly, simple, low cost, and efficient, offering great promise for quick determination of active compounds in TCMs and natural plants.

Application of dispersive liquid-liquid-solidified floating organic drop microextraction and ETAAS for the preconcentration and determination of indium.

A new, simple and efficient method, including dispersive liquid-liquid-solidified floating organic drop microextraction and then electrothermal atomic absorption spectrometry, has been developed for the preconcentration and determination of ultratrace amounts of indium. The method was applied to preconcentrate the indium-1-(2-pyridylazo)-2-naphthol complex in 25μL 1-undecanol. The various factors affecting the extraction efficiency, such as pH, type and volume of extraction solvent, type and volume of disperser solvent, sample volume, ionic strength, and ligand concentration, were investigated and optimized. Under the optimum conditions, an enrichment factor of 62.5, precision of ±4.75%, a detection limit of 55.6 ng L-1, and for the calibration graph a linear range of 96.0-3360 ng L-1 were obtained. The method was used for the extraction and determination of indium in water and standard samples with satisfactory results. Graphical Abstract Preconcentration of indium ions via liquid-liquid-solidified floating organic drop microextraction method and determination by ETAAS.

Determination of five endosulfan pesticides in the fish pond water by dispersive liquid–liquid microextraction combined with GC–MS

ABSTRACTA simple and rapid dispersive liquid–liquid microextraction (DLLME) technique coupled with gas chromatography–ion trap mass spectrometry (GC–MS) was developed for the extraction and analysis of five endosulfan pesticides from the fish pond water. In this work, different parameters affecting the extraction process such as the type and volume of extraction solvent, type and volume of disperser solvent, and extraction time were studied and optimized. Under optimized conditions, the enrichment factor ranged from 189 to 269 and the relative recovery ranged from 88.5% to 94.9%. The linear range was 2.0–80.0 µg/L; the limits of detection and quantitation were in the range 0.04–1.06 µg/L and 0.12–3.53 µg/L, respectively. The relative standard deviations were in the range 0.94%–2.08% (n = 5). The obtained results show that DLLME combined with GC–MS is a fast and simple method for the determination of endosulfan pesticides in fish pond water.

Salting-Out Assisted Liquid-Liquid Extraction Combined with HPLC for Quantitative Extraction of Trace Multiclass Pesticide Residues from Environmental Waters

In this study, salting-out assisted liquid-liquid extraction combined with high performance liquid chromatography diode array detector (SALLE-HPLC-DAD) method was developed and validated for simultaneous analysis of carbaryl, atrazine, propazine, chlorothalonil, dimethametryn and terbutryn in environmental water samples. Parameters affecting the extraction efficiency such as type and volume of extraction solvent, sample volume, salt type and amount, centrifugation speed and time, and sample pH were optimized. Under the optimum extraction conditions the method was linear over the range of 10 - 100 μg/L (carbaryl), 8 - 100 μg/L (atarzine), 7 - 100 μg/L (propazine) and 9 - 100 μg/L (chlorothalonil, terbutryn and dimethametryn) with correlation coefficients (R2) between 0.99 and 0.999. Limits of detection and quantification ranged from 2.0 to 2.8 μg/L and 6.7 to 9.5 μg/L, respectively. The extraction recoveries obtained for ground, lake and river waters were in a range of 75.5% to 106.6%, with the intra-day and inter-day relative standard deviation lower than 3.4% for all the target analytes. All of the target analytes were not detected in these samples. Therefore, the proposed SALLE-HPLC-DAD method is simple, rapid, cheap and environmentally friendly for the determination of the aforementioned herbicides, insecticide and fungicide residues in environmental water samples.