1,721,065 research outputs found
Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples
No full textA simple and rapid dispersive liquid?liquid microextraction procedure based on an ionic liquid (ILDLLME) was developed for selective determination of cobalt (Co) with electrothermal atomic absorption spectrometry (ETAAS) detection. Cobalt was initially complexed with 1-nitroso-2-naphtol (1N2N) reagent at pH 4.0. The IL-DLLME procedure was then performed by using a few microliters of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium hexafluorophosphate [C6mim][PF6] as extractant while methanol was the dispersant solvent. After microextraction procedure, the Co-enriched RTIL phase was solubilized in methanol and directly injected into the graphite furnace. The effect of several variables on Co-1N2N complex formation, extraction with the dispersed RTIL phase, and analyte detection with ETAAS, was carefully studied in this work. An enrichment factor of 120 was obtained with only 6 mL of sample solution and under optimal experimental conditions. The resultant limit of detection (LOD) was 3.8 ng/L, while the relative standard deviation (RSD) was 3.4% (at 1 ug/L Co level and n = 10), calculated from the peak height of absorbance signals. The accuracy of the proposed methodology was tested by analysis of a certified reference material. The method was successfully applied for the determination of Co in environmental and biological samples.Fil: Berton, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Wuilloud, Rodolfo German. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentin
Separation and preconcentration of inorganic Se species in tap and natural waters using unfunctionalized nanosilica as sorption material in dispersive micro-solid phase extraction
No full textA highly sensitive and selective method based on dispersive micro-solid phase extraction (D-μ-SPE) technique was developed for the determination of inorganic Se species. A very simple and fast preconcentration procedure involving the use of pure nanosilica for the extraction of Se(IV) complexed with ammonium pyrrolidine dithiocarbamate (APDC) was applied. Elution of the retained Se(IV) species from nanosilica was achieved with ethyl acetate followed by electrothermal atomic absorption spectrometry determination. For speciation analysis, Se(VI) was selectively quantified based on the difference between the concentrations of total inorganic Se and Se(IV) after a pre-reduction step. The interaction between the analyte and the extractant was characterized by FT-IR and an adsorption isotherm study. A 90% extraction efficiency was achieved after optimization of all factors concerning the extraction and elution steps, such as pH, ionic strength and type of chelating agent. Optimized conditions included pH = 2.0, 4.9 μmol L−1 APDC and the use of 1 mg nanosilica as adsorbent. A limit of detection of 1.4 ng L−1, a relative standard deviation of 4.8% and a 90-fold enhancement factor were obtained with 10 mL of sample. The developed method was finally applied to water samples from different origins and compositions, including rain, tap, underground, and sea.Fil: Llaver, Mauricio. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; ArgentinaFil: Wuilloud, Rodolfo German. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; Argentin
Studying the effect of an ionic liquid on cloud point extraction technique for highly efficient preconcentration and speciation analysis of tellurium in water, soil and sediment samples
No full textA simple, novel and highly sensitive ionic liquid-assisted cloud point extraction (IL-CPE) and preconcentration method was developed for the determination and speciation analysis of tellurium, using 1-octyl-3-methylimidazolium chloride as an additive for improving the extraction efficiency of Triton X-114. The Te(IV) species was complexed with ammonium pyrrolidine dithiocarbamate, extracted into the micellar IL/surfactant phase and then directly measured by electrothermal atomic absorption spectrometry (ETAAS). The total Te concentration was obtained after a pre-reduction step and Te(VI) concentration was calculated as the difference between total Te and Te(IV). Several parameters, including the type and concentration of IL and surfactant, time and temperature of the IL-CPE procedure and ETAAS conditions were thoroughly evaluated and optimized. In addition, the action mechanism of the IL on CPE was studied by fluorescence measurements using Laurdan as a polarity probe. The decrease in the internal polarity caused by the incorporation of the IL into the micelles was responsible for the improvement in the extraction efficiency. Under the optimized conditions, a sensitivity enhancement factor of 87 and an extraction efficiency of 90% were achieved. Limits of detection of 1.1 and 1.7 ng L−1 and relative standard deviations of 3.9% and 5.0% for Te(IV) and Te(VI), respectively, were obtained. The developed IL-CPE method was successfully applied for Te speciation analysis in matrices of different complexities, such as waters (tap, underground and seawater), soil and sediment.Fil: Llaver, Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Wuilloud, Rodolfo German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentin
Enhanced spectrophotometric detection of Hg in water samples by surface plasmon resonance of Au nanoparticles after preconcentration with vortex-assisted liquid-liquid microextraction
Full text linkThis article presents an efficient, simple, and cost-effective method for the determination of trace amounts of Hg by vortex-assisted liquid-liquid microextraction (VALLME) coupled to microvolume UV-Vis spectrophotometry. This method correlates changes in the intensity of localized surface plasmon resonance (LSPR) of tetraoctylammonium bromide (TOABr) coated Au nanoparticles (NPs) after interaction with Hg2+ ion. Spectroscopic measurements of the TOABr-coated Au NPs phase with particular absorption properties (strong and well-defined absorption bands) after analyte extraction by VALLME, provide an accurate and sensitive determination of Hg in water samples, comparable with measurements obtained by atomic absorption spectrometry (AAS). Different variables including sample volume, extraction time, and TOABr-coated Au NPs dispersion volume were carefully studied; final experimental conditions were 5 mL, 120 μL and 5 min respectively. The limit of detection (LOD) was 0.8 ng mL- 1. The calibration curve was linear at concentrations between the limit of quantification (LOQ) (4.9 ng mL- 1) and up to at least 120 ng mL- 1 of Hg. The relative standard deviation for six replicate determinations of 20 ng mL- 1 of Hg was 4.7%. This method exhibited an excellent analytical performance in terms of selectivity and sensitivity and it was finally applied for Hg determination in spiked tap and mineral water samples.Fil: Martinis, Estefanía Mabel. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Wuilloud, Rodolfo German. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentin
Ionic liquids: multi‐role actors in elemental speciation analysis
No full textElemental speciation is a concept that results extremely relevant in nutritional, toxicity and environmental studies as it generates crucial information to fully understand the bioavailability and toxicity of an element1. However, high selectivity and sensitivity are the main demands to be covered by analytical methods for trace elements speciation studies. To accomplish these goals, the combination of a selective separation technique with highly sensitive detectors has been the main strategy. Although any kind of separation technique is feasible, chromatographic techniques are easily coupled to elemental specific detectors. Likewise, non-chromatographic separation techniques can also be used for speciation analysis, but with a more limited separation power. In any case, both methodological approaches require constant improvements due to the high complexity to analyze the speciation of some elements and the difficulty imposed by sample matrices. Ionic Liquids (ILs) are recognized as modern solvents with remarkable properties such as low volatility, high conductivity, and the possibility of offering multiple interactions with different chemical species. Therefore, they have found wide application in different fields of analytical chemistry. In fact, ILs have been proposed as highly efficient extraction phases for separation and preconcentration, while their particular interactions with solutes show them as excellent tools in chromatography as well2. Moreover, the potential of ILs for the separation and preconcentration of trace elements can be further extended beyond their own limits when they are combined with different types of nanomaterials, and properties such as magnetism can be imparted to these extraction phases for more practical microextraction procedures. In this lecture, recent advances on the development of non-chromatographic and chromatographic separation methods using ILs for elemental speciation analysis will be presented. The development of modern liquid-liquid and solid-phase microextraction techniques (e.g. dispersive liquid-liquid microextraction (DLLME) and dispersive microsolid phase extraction (D-µ-SPE)) based on ILs and their combination with certain nanomaterials will be discussed. Also, the application of ILs for the determination of elemental species by HPLC-elemental specific detector hyphenated techniques will be presented, along with the benefits and potential drawbacks of their application when they are coupled to atomic spectrometry-based techniques.Fil: Wuilloud, Rodolfo German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; ArgentinaColloquium Spectroscopicum Internationale XLI; First Latin-American Meeting on Laser Induced Breakdown SpectroscopyCiudad de MéxicoMéxicoUniversidad Nacional Autónoma de MéxicoInstituto de Ciencias Aplicadas y TecnologíaSociedad Mexicana de FísicaSociedad Química de Méxic
Ionic liquid-based microextraction techniques for trace-element analysis
Full text linkIonic liquid-based liquid-liquid microextraction (IL-LLME) techniques are turning into remarkable tools to develop greener sample-preparation methods in analytical chemistry. The application of ILs in LLME is receiving particular attention due to their unique physico-chemical properties, such as undetectable vapor pressure, versatility arising from high conformational possibilities, variable viscosity and density, and their miscibility with other solvents. ILs can be structurally designed to extract target analytes selectively based on unique molecular interactions, leading to highly efficient extraction procedures. In recent years, a wide range of microextraction techniques implementing ILs as successful extraction phases have been proposed. The present work outlines the latest applications of IL-LLME for trace-element analysis, focusing on those challenges arisen during the analysis of complex samples. We also discuss environmental and health aspects related to the use of IL-LLME. Finally, we present the outlook for potential applications and further developments of IL-LLME techniques.Fil: Martinis, Estefanía Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Berton, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Wuilloud, Rodolfo German. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentin
Knotted reactors and their role in flow-injection on-line preconcentration systems coupled to atomic spectrometry-based detectors
Full text linkThe progress in flow-injection (FI) on-line separation and preconcentration employing knotted reactors (KRs) as a sorption medium for organometallic complexes associated to atomic spectrometry techniques is reviewed in this article, focusing the attention on the more frequently complexing agents used. In the last years, the KR has demonstrated to be an excellent alternative in the FI on-line preconcentration procedures; the on-line preconcentration and separation of different metallic species on the inner walls of the KR have been developed utilizing diverse organic and inorganic reagents. The choice of complexing reagents, the coupling of the FI preconcentration system to atomic spectrometry techniques, and the application of the methodologies developed to different samples are discussed.Fil: Cerutti, Estela Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Wuilloud, Rodolfo German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. National Center For Toxicological Research. Food And Drug Administration; Estados UnidosFil: Martinez, Luis Dante. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentin
Desarrollo de tecnologías químicas extractivas para la recuperación de subproductos a base de queratina a partir de desechos de la industria porcina.
No full textMediante este proyecto se ha logrado obtener un subproducto de base queratínica aplicando métodos sencillos (que no requieran de equipos sofisticados), viables económicamente y que no provocan daños en el medio ambiente. El trabajo plantea la extracción de queratina de pelos de cerdo mediante hidrólisis alcalina de solución acuosa de cenizas, y la evaluación de las características de dicho extracto para posteriores aplicaciones. En este sentido, la finalidad de la investigación es la recuperación de subproductos de origen animal ricos en queratina para darle un valor agregado, apostando a la innovación científica y tecnológica, a la diversificación productiva y la sustentabilidad.Fil: Lucero, Maria Noelia. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Castro, Gisela. Instituto de Educación Superior Alvear; ArgentinaFil: Wuilloud, Rodolfo German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaIV Jornadas de Enseñanza e Investigación de las Ciencias ExperimentalesSan RafaelArgentinaUniversidad Nacional de Cuyo. Facultad de Ciencias Aplicadas a la Industri
Capabilities of several phosphonium ionic liquids for arsenic species determination in water by liquid-liquid microextraction and electrothermal atomic absorption spectrometry
No full textThe capabilities of several phosphonium-ionic liquids (PILs) to form ion-pairs with a complex obtained by reaction of arsenate species with molybdate were evaluated. Phosphonium-ILs containing the tetradecyl(trihexyl)phosphonium cation but different anions (dicyanamide and decanoate) and tributyl(methyl)phosphonium methylsulphate IL were studied. Size, polarity and localization of charges in PILs cations showed to influence their capability to form ion-pairs with arsenomolybdate (AsMo12O403-) complex and to extract As(V). The performance of PILs was compared with that showed by a widely used ion-pairing reagent such as cethyltrimethylamonium bromide (CTAB). Finally, the IL tetradecyl(trihexyl)phosphonium dicyanamide was chosen to develop a liquid-liquid microextraction (LLME) procedure using only 80 μL of tetrachloroethylene as extractant. The organic phase was directly injected into the graphite furnace of an electrothermal atomic absorption spectrometer (ETAAS) for As determination. An extraction efficiency of 100% and a preconcentration factor of 130 were obtained with 5 mL of sample. The detection limit was 1.9 ng L-1 and the relative standard deviation for six replicate measurements of 1.0 μg L-1 for As were 4.9%, 5.0% and 5.1% for As(V), As(III) and organic As species, respectively.Fil: Castro Grijalba, Alexander. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; ArgentinaFil: Escudero, Leticia Belén. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; ArgentinaFil: Wuilloud, Rodolfo German. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; Argentin
Polymer-supported ionic liquid solid phase extraction for trace inorganic and organic mercury determination in water samples by flow injection-cold vapor atomic absorption spectrometry
Full text linkA simple and green technique named polymer-supported ionic liquid solid phase extraction (PSIL-SPE) was developed for mercury (Hg) species determination. Inorganic Hg (InHg) species was complexed with chloride ions followed by its introduction into a flow injection on-line system to quantitatively retain the anionic chlorocomplex (HgCl42−) in a column packed with CYPHOS® IL 101-impregnated resin. The trapped InHg was then reduced with stannous chloride (SnCl2) and eluted with the same flow of reducing agent followed by cold vapor atomic absorption spectrometry (CV-AAS) detection. Organic mercury species (OrgHg) did not interact with the impregnated resin and were not retained into the column. Total concentration of OrgHg was evaluated by difference between total Hg and InHg concentration. A 95% extraction efficiency was achieved for InHg when the procedure was developed under optimal experimental conditions. The limit of detection obtained for preconcentration of 40 mL of sample was 2.4 ng L−1 InHg. The relative standard deviation (RSD) was 2.7% (at 1 µg L−1 InHg and n=10) calculated from the peak height of absorbance signals (Gaussian-shape and reproducible peaks). This work reports the first polymer-supported IL solid phase extraction approach implemented in a flow injection on-line system for determination of Hg species in mineral, tap and river water samples.Fil: Escudero, Leticia Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; ArgentinaFil: Olsina, Roberto Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Química de San Luis; ArgentinaFil: Wuilloud, Rodolfo German. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Química Analítica para Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mendoza; Argentin
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