A quartz tube atomizer with tungsten coil: a new system for vapor atomization in atomic absorption spectrometry

A quartz tube atomizer with a tungsten coil (QTAW) is described for the determination of arsenic in a flow injection hydride generation system. The flow injection system includes a Nafion(R) membrane that continuously dries the gaseous species, allowing removal of 4.2 mg min(-1) of water, corresponding to an efficiency of 92.7%. The application of this system to the determination of arsenic, using the optimized conditions, shows considerable stability with time, without loss of sensitivity, and it was possible to obtain a calibration curve with a wide range (up to 500 mg l(-1)), with R-2 = 0.9998, a limit of detection of 1.5 mg l(-1) and an analytical frequency of 60 determinations per hour. The determination of arsenic in samples of mineral and sea-waters, sediment and biological materials, shows good accuracy and precision between the results obtained and the certified values for the recovery of arsenic, with RSD values less than 6%.17111516152

Ion mobility mass spectrometry: an elegant alternative focusing on speciation studies

This work is proposed to demonstrate the Traveling-Wave Ion Mobility Specrometry (TWIMS) coupled to Mass Spectrometry (MS) as an alternative technique for speciation analysis between metals/metalloids and biomolecules. Mobilities of bovine carbonic anhydrase bound to Ba(2+), Cu(2+), Pb(2+), Zn(2+), Cr(3+), Cr(6+), Se(4+) and Se(6+) were estimated. The metal belonging to the bovine carbonic anhydrase structure, commonly found in the commercially available enzyme, was removed by filtration, using centrifugal filter devices. Then, some metals/metalloids were added to 10.0 mmol L(-1) ammonium acetate at pH = 6.8 enzyme solution. Experiments were carried out by direct insertion of the sample at 10 mu L min(-1) flow rate into the ESI source of the instrument. Carbonic anhydrase mobility varied according to the metal bound in its structure, following the order: Zn(2+) < Cu(2+) < Ba(2+) < Pb(2+). Metals with higher affinity by the enzyme, such as Zn(2+) and Cu(2+) had lower mobility, suggesting a higher structural modification, binding itself to the enzyme metallic site. Considering metals with different oxidation states, the enzyme mobility followed the order: Se(4+) < Cr(6+) < Se(6+) < Cr(3+).26120120

Evaluation of metal-ion stress in sunflower (Helianthus annuus L.) leaves through proteomic changes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)In this work, sunflowers (Helianthus annuus L.) were cultivated using soil and vermicompost as substrate, and plant irrigation was carried out using either a Zn solution or a mixed ions solution (Cd, Cu, Pb and Zn). After plant harvesting, the effects of metal-ion contamination on proteins expression (either up- or down-regulation) in sunflower leaves were evaluated using two-dimensional electrophoresis (2-DE), gel images and mass spectrometry (MALDI-QTOF MS). When Zn or mixed ions solution was added to the substrate, nine proteins showed different expressions. Another twenty-three protein spots also showed considerable variation when both treatments (Zn or mixed ions) were applied. Twelve of these proteins were successfully characterized, six of them being reported for the first time in Helianthus annuus L. Two other proteins showed new sequences that have been downloaded to the protein databank.11107113Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Financiadora de Estudos e Projetos (FINEP)Proteomic Network of the Sao PauloFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Comparative metallomics for transgenic and non-transgenic soybeans

In this work, a comparative metallomics of transgenic and non- transgenic soybeans [ Glycine max ( L.) Merrill] was performed. Soybean proteins were extracted with a proper buffer and separated by two- dimensional polyacrylamide gel electrophoresis. Metal ions bound to a set of eight proteins randomly selected ( ranging from 13.98 to 54.87 kDa), were characterized by matrixassisted laser desorption- ionization quadrupole- time of flight mass spectrometry and mapped using synchrotron radiation X- ray spectrometry. The metal ions detected were: Ca( II), Cu( II), Fe( II), Mn( II), Ni( II) and Zn( II). Transgenic and non- transgenic soybeans proteins were found to display typical and random profiles for metal ions binding. To test the reliability of the qualitative metal ions profiles, quantification of Ca( II), Cu( II) and Fe( II) was performed via microwave-assisted decomposition in mini- vials followed by atomic absorption spectrometry determination. Qualitative and quantitative metallomics was found to be coherent and to match profiles expected from the known protein functions. The protein of spot 5, with molar mass of 37.62 kDa ( amino acid sequence presented), was found to display the most characteristic change in metal ions content, with higher Ca( II), Cu( II) and Fe( II) concentrations for transgenic soybeans.22121501150

Quantitation of drugs via molecularly imprinted polymer solid phase extraction and electrospray ionization mass spectrometry: benzodiazepines in human plasma

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The association of solid phase extraction with molecularly imprinted polymers (MIP) and electrospray ionization mass spectrometry (ESI-MS) is applied to the direct extraction and quantitation of benzodiazepines in human plasma. The target analytes are sequestered by MIP and directly analyzed by ESI-MS. Due to the MIP highly selective extraction, ionic suppression during ESI is minimized; hence no separation is necessary prior to ESI-MS, which greatly increases analytical speed. Benzodiazepines (medazepam, nitrazepam, diazepam, chlordiazepoxide, clonazepam and midazolam) in human plasma were chosen as a proof-of-principle case of drug analyses by MIP-ESI-MS in a complex matrix. MIP-ESI-MS displayed good figures of merits for medazepam, nitrazepam, diazepam, chlordiazepoxide and midazolam, with analytical calibration curves ranging from 10 to 250 mu g L(-1) (r > 0.98) with limit of quantification <10 mu g L(-1) and acceptable within-day and between-day precision and accuracy.1361837533757Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Ministerio de Ciencia e Tecnologia (INOMAT)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG, Belo Horizonte, Brazil) [CDS-APQ-01323-09, CDS-APQ-01612-10

Determination of tin and lead in sediment slurries by graphite furnace atomic absorption spectrometry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Methods were determined for lead and tin determinations in river, marine and lake sediments by slurry sampling and graphite furnace atomic absorption spectrometry. The optimizations were carried out using River Sediment BCR 320 and Marine Sediment PACS-2 for Pb and Sn, respectively. For Pb determination, the parameters studied included inorganic acid mixture, stabilizing agent, sample mass and sonication time. The influence of diluents and the extraction to the liquid phase for two different matrices was evaluated for Sn. The Pb content in the slurry liquid phase was ca. 56%, and ranged from 75% to 100% for Sn. Representative masses of 34 and 45 mg, and effective masses of 12 and 48 mu g for Pb and Sn, respectively, were obtained under optimized conditions. Detection and quantification limits of 0.2 and 0.7 mu g g(-1) for Pb, and 1.5-2.6 and 4.5-7.6 mu g g(-1) for Sn were obtained.16441732445451Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Financiadora de Estudos e Projetos (FINEP, Rio de Janeiro, Brazil)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [05/52975-9

Optimization of a hydride generation metallic furnace atomic absorption spectrometry (HG-MF-AAS) method for tin determination: Analytical and morphological parameters of a metallic atomizer

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The present work describes a metallic tube as hydride atomizer for atomic absorption spectrometry. Its performance is evaluated through tin determination, and the accuracy of the method assessed through the analysis of sediment and water samples. Some chemical parameters (referring to the generation of the hydride) such as acid, NaOH and THB concentrations, as well as physical parameters (referring to the transport of the hydride) such as carrier, acetylene, air flow-rates, flame composition, coil length, tube hole area, among others, are evaluated for optimization of the method. Scanning electron microscopy is used for evaluating morphological parameters in both new and used (after 150 h) tube atomizers. The method presents linear Sn concentration from 50 to 1000 mu g L-1 (r > 0.9995; n=3) and the analytical frequency of ca. 40 h(-1). The limit of detection (LOD) is 7.1 mu g L-1 and the precision, expressed as RSD is less than 4% (200 mu g L-1; n=10). The accuracy is evaluated through reference materials, and the results are similar at 95% confidence level according to the t-test. (C) 2013 Elsevier B.V. All rights reserved.117543548Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Thermospray flame furnace atomic absorption spectrometry for determination of silver in biological materials

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)A method for silver determination without concentration steps is described using thermospray flame furnace atomic absorption spectrometry. Carrier type and flow rate, sample volume, flame conditions (acetylene and air flow rate), water flow rate in the nebulizer, metallic tube and type and concentration of the acid diluent of the analyte are the parameters evaluated in the optimization of the method. Using the optimized conditions, eleven elements are evaluated as concomitants. The limits of detection and quantification are 0.15 mu gL(-1) and 0.50 mu gL(-1), respectively. The linear range is from 0.50 mu gL(-1) to 40 mu gL(-1) and the accuracy of the method is obtained through two certified reference materials: MA-A-2 (fish flesh homogenate) and SRM 1643e (trace elements in water). (C) 2012 Elsevier B.V. All rights reserved.97395399Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Online preconcentration/determination of cadmium using grape bagasse in a flow system coupled to thermospray flame furnace atomic absorption spectrometry

Thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) was employed for Cd(II) determination after online preconcentration. In this system, Cd(II) ions were adsorbed onto a minicolumn packed with grape bagasse. The elution of the metal ions was made with 1 mol L-1 HCl. Various parameters, such as pH, eluent type, concentration, volume, flow rate for preconcentration, and effect of interfering ions on the retention of the metal ions have been studied. The optimum pH for the adsorption was 3.0. The enrichment factor was 33.7. The limits of detection and quantification for Cd(II) were 0.03 and 0.11 mu g L-1, respectively. The repetitivity and precision were 5.0 ( 5 minicolumns) and 4.6% (n = 18). The stability of the minicolumns was evaluated from successive preconcentration/elution cycles ( 80 cycles, RSD 3.9%). The proposed method was applied for cadmium determination from certified reference materials, and good agreement was obtained at the 95% confidence level.39675576