The Experts below are selected from a list of 8154 Experts worldwide ranked by ideXlab platform
Miguel Valcárcel - One of the best experts on this subject based on the ideXlab platform.
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Effervescence assisted dispersive liquid-liquid microextraction with extractant removal by magnetic nanoparticles.
Analytica chimica acta, 2013Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad Cárdenas, Miguel ValcárcelAbstract:Abstract In this article, Effervescence assisted dispersive liquid–liquid microextraction with extractant removal by magnetic nanoparticles is presented for the first time. The extraction technique makes use of a mixture of 1-octanol and bare Fe 3 O 4 magnetic nanoparticles (MNPs) in acetic acid. This mixture is injected into the sample, which is previously fortified with carbonate, and as a consequence of the Effervescence reaction, CO 2 bubbles are generated making possible the easy dispersion of the extraction solvent. In addition, the MNPs facilitates the recovery of the 1-octanol after the extraction thanks to the interaction between hydroxyl groups present at the surface of the MNPs and the alcohol functional group of the solvent. The extraction mode has been optimized and characterized using the determination of six herbicides in water samples as model analytical problem. The enrichment factors obtained for the analytes were in the range 21–185. These values permit the determination of the target analytes at the low microgram per liter range with good precision (relative standard deviations lower than 11.7%) using gas chromatography (GC) coupled to mass spectrometry (MS) as analytical technique.
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Effervescence-assisted carbon nanotubes dispersion for the micro-solid-phase extraction of triazine herbicides from environmental waters.
Analytical and bioanalytical chemistry, 2013Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad Cárdenas, Miguel ValcárcelAbstract:Extraction techniques are surface-dependent processes since their kinetic directly depends on the contact area between the sample and the extractant phase. The dispersion of the extractant (liquid or solid) increases this area improving the extraction efficiency. In this article, the dispersion of a nanostructured sorbent at the very low milligram level is achieved by Effervescence thanks to the in situ generation of carbon dioxide. For this purpose, a special tablet containing the Effervescence precursors (sodium carbonate as carbon dioxide source and sodium dihydrogen phosphate as proton donor) and the sorbent [multiwalled carbon nanotubes (MWCNTs)] is prepared. All the microextraction steps take place in a glass beaker containing 100 mL of the sample. After the extraction, the MWCNTs, enriched with the extracted analytes, are recovered by vacuum filtration. Methanol was selected to elute the retained analytes. The extraction mode is optimized and characterized using the determination of nine herbicides in water samples as model analytical problem. The absolute recoveries of the analytes were in the range 48–76 %, while relative recoveries were close to 100 % in all cases. These values permit the determination of these analytes at the low microgram per liter range with good precision (relative standard deviations lower than 9.3 %) using ultra performance liquid chromatography (UPLC) combined with ultraviolet detection (UV).
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Effervescence-assisted dispersive micro-solid phase extraction.
Journal of chromatography. A, 2011Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad Cárdenas, Miguel ValcárcelAbstract:Extraction techniques are surface dependent processes since their kinetic directly depends on the contact area between the sample and the extractant phase. The dispersion of the extractant (liquid or solid) increases this area improving the extraction efficiency. In this article, the dispersion of the sorbent at the very low milligram level is achieved by Effervescence thanks to the in situ generation of carbon dioxide. For this purpose a special tablet containing the Effervescence precursors (sodium carbonate as carbon dioxide source and sodium dihydrogen phosphate as proton donor) and the sorbent (OASIS-HLB) is fabricated. All the microextraction process takes place in a 10 mL-glass syringe and the solid, enriched with the extracted analytes, is recovered by filtration. Acetonitrile was selected to elute the retained analytes. The extraction mode is characterized and optimized using the determination of five nitroaromatic compounds in water. The absolute recoveries of the analytes were in the range 61-85% while relative recoveries close to 100% in all cases, which demonstrates the absence of matrix effect on the extraction. These values permit the determination of these analytes at the microgram per liter range with good precision (relative standard deviations lower than 6.1%) using ultra performance liquid chromatography (UPLC) combined with ultraviolet (UV) detection as instrumental technique.
Guillermo Lasarte-aragonés - One of the best experts on this subject based on the ideXlab platform.
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Effervescence-Assisted Microextraction—One Decade of Developments
Molecules (Basel Switzerland), 2020Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad CárdenasAbstract:Dispersive microextraction techniques are key in the analytical sample treatment context as they combine a favored thermodynamics and kinetics isolation of the target analytes from the sample matrix. The dispersion of the extractant in the form of tiny particles or drops, depending on the technique, into the sample enlarges the contact surface area between phases, thus enhancing the mass transference. This dispersion can be achieved by applying external energy sources, the use of chemicals, or the combination of both strategies. Effervescence-assisted microextraction emerged in 2011 as a new alternative in this context. The technique uses in situ-generated carbon dioxide as the disperser, and it has been successfully applied in the solid-phase and liquid-phase microextraction fields. This minireview explains the main fundamentals of the technique, its potential and the main developments reported.
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Effervescence assisted dispersive liquid-liquid microextraction with extractant removal by magnetic nanoparticles.
Analytica chimica acta, 2013Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad Cárdenas, Miguel ValcárcelAbstract:Abstract In this article, Effervescence assisted dispersive liquid–liquid microextraction with extractant removal by magnetic nanoparticles is presented for the first time. The extraction technique makes use of a mixture of 1-octanol and bare Fe 3 O 4 magnetic nanoparticles (MNPs) in acetic acid. This mixture is injected into the sample, which is previously fortified with carbonate, and as a consequence of the Effervescence reaction, CO 2 bubbles are generated making possible the easy dispersion of the extraction solvent. In addition, the MNPs facilitates the recovery of the 1-octanol after the extraction thanks to the interaction between hydroxyl groups present at the surface of the MNPs and the alcohol functional group of the solvent. The extraction mode has been optimized and characterized using the determination of six herbicides in water samples as model analytical problem. The enrichment factors obtained for the analytes were in the range 21–185. These values permit the determination of the target analytes at the low microgram per liter range with good precision (relative standard deviations lower than 11.7%) using gas chromatography (GC) coupled to mass spectrometry (MS) as analytical technique.
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Effervescence-assisted carbon nanotubes dispersion for the micro-solid-phase extraction of triazine herbicides from environmental waters.
Analytical and bioanalytical chemistry, 2013Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad Cárdenas, Miguel ValcárcelAbstract:Extraction techniques are surface-dependent processes since their kinetic directly depends on the contact area between the sample and the extractant phase. The dispersion of the extractant (liquid or solid) increases this area improving the extraction efficiency. In this article, the dispersion of a nanostructured sorbent at the very low milligram level is achieved by Effervescence thanks to the in situ generation of carbon dioxide. For this purpose, a special tablet containing the Effervescence precursors (sodium carbonate as carbon dioxide source and sodium dihydrogen phosphate as proton donor) and the sorbent [multiwalled carbon nanotubes (MWCNTs)] is prepared. All the microextraction steps take place in a glass beaker containing 100 mL of the sample. After the extraction, the MWCNTs, enriched with the extracted analytes, are recovered by vacuum filtration. Methanol was selected to elute the retained analytes. The extraction mode is optimized and characterized using the determination of nine herbicides in water samples as model analytical problem. The absolute recoveries of the analytes were in the range 48–76 %, while relative recoveries were close to 100 % in all cases. These values permit the determination of these analytes at the low microgram per liter range with good precision (relative standard deviations lower than 9.3 %) using ultra performance liquid chromatography (UPLC) combined with ultraviolet detection (UV).
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Effervescence-assisted dispersive micro-solid phase extraction.
Journal of chromatography. A, 2011Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad Cárdenas, Miguel ValcárcelAbstract:Extraction techniques are surface dependent processes since their kinetic directly depends on the contact area between the sample and the extractant phase. The dispersion of the extractant (liquid or solid) increases this area improving the extraction efficiency. In this article, the dispersion of the sorbent at the very low milligram level is achieved by Effervescence thanks to the in situ generation of carbon dioxide. For this purpose a special tablet containing the Effervescence precursors (sodium carbonate as carbon dioxide source and sodium dihydrogen phosphate as proton donor) and the sorbent (OASIS-HLB) is fabricated. All the microextraction process takes place in a 10 mL-glass syringe and the solid, enriched with the extracted analytes, is recovered by filtration. Acetonitrile was selected to elute the retained analytes. The extraction mode is characterized and optimized using the determination of five nitroaromatic compounds in water. The absolute recoveries of the analytes were in the range 61-85% while relative recoveries close to 100% in all cases, which demonstrates the absence of matrix effect on the extraction. These values permit the determination of these analytes at the microgram per liter range with good precision (relative standard deviations lower than 6.1%) using ultra performance liquid chromatography (UPLC) combined with ultraviolet (UV) detection as instrumental technique.
Xu Jing - One of the best experts on this subject based on the ideXlab platform.
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An Effervescence tablet-assisted microextraction based on the solidification of deep eutectic solvents for the determination of strobilurin fungicides in water, juice, wine, and vinegar samples by HPLC.
Food chemistry, 2020Co-Authors: Liyan Jia, Xin Huang, Wenfei Zhao, Huihui Wang, Xu JingAbstract:Abstract In this study, a simple, efficient, and green Effervescence tablet-assisted microextraction method based on the solidification of deep eutectic solvent (ETA-ME-SDES) was developed to determine picoxystrobin, pyraclostrobin, and trifloxystrobin in water, juice, wine, and vinegar samples by HPLC. An eco-friendly, hydrophobic, deep eutectic solvent (DES, acting as the extraction solvent) was synthesized by thymol and octanoic acid in the molar ratio of 1:5. The extraction solvent dispersed in sample solutions with the assistance of pH adjustment and Effervescence reaction, and was collected after solidification in an ice bath. Several essential conditions, including the type and the volume of DESs, the amount of ammonia hydroxide, and the components of Effervescence tablets were optimized. The limits of detection ranged from 0.15 to 0.38 μg L−1. Extraction recovery ranged from 77.4 to 106.9%. The proposed method was successful in determining the amount of strobilurin fungicides in water, juice, wine, and vinegar samples.
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Magnetic Effervescence tablet-assisted switchable hydrophilicity solvent-based liquid phase microextraction of triazine herbicides in water samples
Journal of Molecular Liquids, 2020Co-Authors: Xu Jing, Wenfei Zhao, Huihui Wang, Cheng Xiaoyu, Xiaowen WangAbstract:Abstract A method for the determination of triazine herbicides in water samples was established by magnetic Effervescence tablet-assisted switchable hydrophilicity solvent-based liquid phase microextraction procedure (META-SHS-LPME) coupled with high-performance liquid chromatography with diode array detection. The magnetic Effervescence tablet, composed of citric acid, sodium hexanoate, sodium bicarbonate, and Fe3O4 nanoparticles, combined extractant generation, dispersion, and magnetic recovery into one step. Citric acid could react with sodium hexanoate and sodium bicarbonate to generate hexanoic acid and carbon dioxide in situ, respectively. Carbon dioxide bubbles assisted the eco-friendly extractant hexanoic acid to fully contact with target compounds. Fe3O4 nanoparticles containing extractant and triazine herbicides were isolated from the sample solution using an external magnet. Good linearity was achieved in the range of 50–5000 ng mL−1 with a correlation coefficient greater than 0.997. The limit of detection was within 0.10–0.13 ng mL−1. The extraction recovery of triazine herbicides were 81.4–96.7% in well, pond, and river waters. Overall, the proposed method was a simple, efficient, and eco-friendly analytical approach for determining triazine herbicide residues in water samples.
Andrey Bulatov - One of the best experts on this subject based on the ideXlab platform.
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An Effervescence tablet-assisted switchable solvent-based microextraction: On-site preconcentration of steroid hormones in water samples followed by HPLC-UV determination
Journal of Molecular Liquids, 2017Co-Authors: Andrey Shishov, Ivan Sviridov, Irina Timofeeva, Natalia Chibisova, Leonid Moskvin, Andrey BulatovAbstract:Abstract An Effervescence tablet-assisted switchable solvent-based microextraction (ETA-SHS-ME) strategy for the on-site pretreatment of water samples was developed in this study. The performance of the suggested strategy was demonstrated by the HPLC-UV determination of steroid hormones (testosterone, progesterone, estradiol and hydrocortisone) in water samples. This analytical task was used as a proof-of-concept example. The ETA-SHS-ME procedure involves dissolution of two effervescent tablets containing a solid proton donor agent (oxalic acid) and an effervescency (NaHCO3) agent as well as a source of organic phase (sodium nonate) in water sample. The proton donor agent reacts with the effervescency agent and water-soluble source of organic phase in aqueous sample phase. The pH changing promotes conversion of sodium nonate into a water-insoluble nonanoic acid dispersed by carbon dioxide bubbles generated in situ. After phase separation an organic phase containing steroid hormones is collected and delivered to a laboratory, and HPLC-UV analysis is performed. The linear calibration ranges were from 5 to 500 ng L− 1 for testosterone, from 25 to 750 ng L− 1 for progesterone, from 10 to 1000 ng L− 1 for estradiol and from 50 to 500 ng L− 1 for hydrocortisone. The LODs, calculated from the blank tests based on 3σ, were 2, 8, 3 and 17 ng L− 1, respectively. The method was successfully applied to the analysis of river samples. Novelty Statement. In this research, for the first time, the Effervescence tablet-assisted switchable solvent-based microextraction (ETA-SHS-ME) approach was developed and successfully applied for on-site sample pretreatment of water samples. The organic phase is generated in situ in the ETA-SHS-ME procedure compared to the reported in literature Effervescence-assisted microextraction approaches. This feature allows to implement microextraction from a large volume of the aqueous sample phase with extremely high enrichment factors. The manufacturing of Effervescence tablets for ETA-SHS-ME is simple due to all agents used are solid substances, which can be easily mixed and compressed. The ETA-SHS-ME was coupled with the HPLC-UV method for the first time and applied for the determination of testosterone, progesterone, estradiol and hydrocortisone in river samples. The Effervescence-assisted microextraction procedure was implemented for the determination of steroid hormones in water samples for the first time.
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Effervescence assisted dispersive liquid–liquid microextraction followed by microvolume UV-Vis spectrophotometric determination of surfactants in water
Toxicological & Environmental Chemistry, 2016Co-Authors: Christina Vakh, Leonid Moskvin, Ekaterina Evdokimova, Alexey Pochivalov, Andrey BulatovAbstract:ABSTRACTThe novel and simple methods for the sensitive determination of cationic and anionic surfactants in water based on Effervescence assisted dispersive liquid–liquid microextraction and microvolume UV-Vis spectrophotometry have been developed. The method involves ion-pair extraction of cationic and anionic surfactants with organic dyes (methyl orange and azure A, respectively) during the dispersion of extraction solvent (CHCl3) by CO2 bubbles which are formed by the injection of a mixture of the extraction solvent and proton donor solvent into the sample solution which contains carbonate-ions as effervescency agent. The analytical performance of the proposed procedure was compared with the conventional dispersive liquid–liquid microextraction. Appropriate experimental conditions for both methods were investigated. The absorbances of the colored extracts at wavelengths of 440 and 625 nm obey Beer's law within the range of 0.1–5.0 mg/L for both cationic and anionic surfactants. The limit of detection (...
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A fully automated Effervescence assisted dispersive liquid-liquid microextraction based on a stepwise injection system. Determination of antipyrine in saliva samples.
Analytica chimica acta, 2015Co-Authors: Kseniia Medinskaia, Leonid Moskvin, Christina Vakh, Darina Aseeva, Vasil Andruch, Andrey BulatovAbstract:A first attempt to automate the Effervescence assisted dispersive liquid-liquid microextraction (EA-DLLME) has been reported. The method is based on the aspiration of a sample and all required aqueous reagents into the stepwise injection analysis (SWIA) manifold, followed by simultaneous counterflow injection of the extraction solvent (dichloromethane), the mixture of the Effervescence agent (0.5 mol L(-1) Na2CO3) and the proton donor solution (1 mol L(-1) CH3COOH). Formation of carbon dioxide microbubbles generated in situ leads to the dispersion of the extraction solvent in the whole aqueous sample and extraction of the analyte into organic phase. Unlike the conventional DLLME, in the case of EA-DLLME, the addition of dispersive solvent, as well as, time consuming centrifugation step for disruption of the cloudy state is avoided. The phase separation was achieved by gentle bubbling of nitrogen stream (2 mL min(-1) during 2 min). The performance of the suggested approach is demonstrated by determination of antipyrine in saliva samples. The procedure is based on the derivatization of antipyrine by nitrite-ion followed by EA-DLLME of 4-nitrosoantipyrine and subsequent UV-Vis detection using SWIA manifold. The absorbance of the yellow-colored extract at the wavelength of 345 nm obeys Beer's law in the range of 1.5-100 µmol L(-1) of antipyrine in saliva. The LOD, calculated from a blank test based on 3σ, was 0.5 µmol L(-1).
Rafael Lucena - One of the best experts on this subject based on the ideXlab platform.
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Effervescence-Assisted Microextraction—One Decade of Developments
Molecules (Basel Switzerland), 2020Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad CárdenasAbstract:Dispersive microextraction techniques are key in the analytical sample treatment context as they combine a favored thermodynamics and kinetics isolation of the target analytes from the sample matrix. The dispersion of the extractant in the form of tiny particles or drops, depending on the technique, into the sample enlarges the contact surface area between phases, thus enhancing the mass transference. This dispersion can be achieved by applying external energy sources, the use of chemicals, or the combination of both strategies. Effervescence-assisted microextraction emerged in 2011 as a new alternative in this context. The technique uses in situ-generated carbon dioxide as the disperser, and it has been successfully applied in the solid-phase and liquid-phase microextraction fields. This minireview explains the main fundamentals of the technique, its potential and the main developments reported.
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Effervescence assisted dispersive liquid-liquid microextraction with extractant removal by magnetic nanoparticles.
Analytica chimica acta, 2013Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad Cárdenas, Miguel ValcárcelAbstract:Abstract In this article, Effervescence assisted dispersive liquid–liquid microextraction with extractant removal by magnetic nanoparticles is presented for the first time. The extraction technique makes use of a mixture of 1-octanol and bare Fe 3 O 4 magnetic nanoparticles (MNPs) in acetic acid. This mixture is injected into the sample, which is previously fortified with carbonate, and as a consequence of the Effervescence reaction, CO 2 bubbles are generated making possible the easy dispersion of the extraction solvent. In addition, the MNPs facilitates the recovery of the 1-octanol after the extraction thanks to the interaction between hydroxyl groups present at the surface of the MNPs and the alcohol functional group of the solvent. The extraction mode has been optimized and characterized using the determination of six herbicides in water samples as model analytical problem. The enrichment factors obtained for the analytes were in the range 21–185. These values permit the determination of the target analytes at the low microgram per liter range with good precision (relative standard deviations lower than 11.7%) using gas chromatography (GC) coupled to mass spectrometry (MS) as analytical technique.
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Effervescence-assisted carbon nanotubes dispersion for the micro-solid-phase extraction of triazine herbicides from environmental waters.
Analytical and bioanalytical chemistry, 2013Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad Cárdenas, Miguel ValcárcelAbstract:Extraction techniques are surface-dependent processes since their kinetic directly depends on the contact area between the sample and the extractant phase. The dispersion of the extractant (liquid or solid) increases this area improving the extraction efficiency. In this article, the dispersion of a nanostructured sorbent at the very low milligram level is achieved by Effervescence thanks to the in situ generation of carbon dioxide. For this purpose, a special tablet containing the Effervescence precursors (sodium carbonate as carbon dioxide source and sodium dihydrogen phosphate as proton donor) and the sorbent [multiwalled carbon nanotubes (MWCNTs)] is prepared. All the microextraction steps take place in a glass beaker containing 100 mL of the sample. After the extraction, the MWCNTs, enriched with the extracted analytes, are recovered by vacuum filtration. Methanol was selected to elute the retained analytes. The extraction mode is optimized and characterized using the determination of nine herbicides in water samples as model analytical problem. The absolute recoveries of the analytes were in the range 48–76 %, while relative recoveries were close to 100 % in all cases. These values permit the determination of these analytes at the low microgram per liter range with good precision (relative standard deviations lower than 9.3 %) using ultra performance liquid chromatography (UPLC) combined with ultraviolet detection (UV).
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Effervescence-assisted dispersive micro-solid phase extraction.
Journal of chromatography. A, 2011Co-Authors: Guillermo Lasarte-aragonés, Rafael Lucena, Soledad Cárdenas, Miguel ValcárcelAbstract:Extraction techniques are surface dependent processes since their kinetic directly depends on the contact area between the sample and the extractant phase. The dispersion of the extractant (liquid or solid) increases this area improving the extraction efficiency. In this article, the dispersion of the sorbent at the very low milligram level is achieved by Effervescence thanks to the in situ generation of carbon dioxide. For this purpose a special tablet containing the Effervescence precursors (sodium carbonate as carbon dioxide source and sodium dihydrogen phosphate as proton donor) and the sorbent (OASIS-HLB) is fabricated. All the microextraction process takes place in a 10 mL-glass syringe and the solid, enriched with the extracted analytes, is recovered by filtration. Acetonitrile was selected to elute the retained analytes. The extraction mode is characterized and optimized using the determination of five nitroaromatic compounds in water. The absolute recoveries of the analytes were in the range 61-85% while relative recoveries close to 100% in all cases, which demonstrates the absence of matrix effect on the extraction. These values permit the determination of these analytes at the microgram per liter range with good precision (relative standard deviations lower than 6.1%) using ultra performance liquid chromatography (UPLC) combined with ultraviolet (UV) detection as instrumental technique.
