A espectrometria atômica e a determinação de elementos metálicos em material polimérico

Polymeric materials are widely used in the chemical industry and are part of our daily lives. Inorganic species may be added to them as additives, anti-oxidizing agents, stabilizers, plasticizers, colorants and catalysts and may be present in a wide range of concentrations. Their determination demands the development of analytical methods considering different kinds of polymeric materials, their composition and the final use of the material. Although many different analytical techniques may be used, this review emphasizes those based on atomic absorption and emission spectrometry. Solid sampling techniques and digestion methods are described and discussed and compared considering published results.

Espectrometria de absorção atômica: o caminho para determinações multi-elementares

This paper present an overview of way covered for the spectrometry of atomic absorption (AAS), tracing a line of the historical events in its development and its establishment as a multielement technique. Additionally, the efforts carried by through several researchers in the search for the instrumental evolution, the advances, advantages, limitations, and trends of this approach are related. Several works focusing its analytical applications are cited employing simultaneous multielement determination by flame (FAAS) and/or graphite furnace (GF AAS), and fast sequential multielement determination using FAAS are reported in the present review.

Aplicação de zeólitas sintéticas como coadjuvante em formulação detergente

The study consists is the application of zeolites NaX, NaY and A as builder in detergent formulations to eliminate the hardness of water. Therefore, the adsorption of ions Ca+2 and Mg+2 were evaluated, and the effect of the cleaning action of the surfactant sodium dodecil sulfate (SDS) through tests of detergency. The experiments were conducted in bath system (with shaking) and quantification of metals was performed by atomic absorption spectrometry. Zeolite A showed the best results for adsorption of Ca++ and Mg++ with retention rates of around 90 and 70% respectively and acted positively on the action of cleaning the surfactant SDS.

Determinação de As, Cd e Pb em amêndoas e mesocarpo de babaçu, sapucaia, xixá e castanha-do-pará por espectrometria de absorção atômica

This work describes methods for the simultaneous determination of Cd and Pb by graphite furnace atomic absorption spectrometry and As by hydride generation atomic absorption spectrometry in Brazilian nuts. The samples (~ 0.300 g) were digested to clear solutions in a closed vessel microwave oven. The pyrolysis and atomization temperatures for simultaneous determinations of Cd and Pb were 1100 and 2100 °C, respectively, using 0.5% (w v-1) NH4H2PO4 + 0.03% (w v-1) Mg(NO3)2 as chemical modifier. The limits of detection (3Δ) were 3.8 μg kg-1 for As, 0.86 μg kg-1 for Cd and 13 μg kg-1 for Pb. The reliability of the entire procedures was confirmed by peach leaves (No. 1547 - NIST) certified reference material analysis and addition and recovery tests. The found concentrations presented no statistical differences at the 95% confidence level.

Parâmetros r e R obtidos de programa interlaboratorial: como usá-los

Intralaboratorial and interlaboratorial variabilities can be obtained by conducting an specially designed interlaboratory program. Using the analysis of variance technique one can calculate the r (repeatability) and R (reproducibility) indexes that can help participant laboratories to monitor their routine quality control procedures. An example is described using data obtained from an interlaboratory program where twelve laboratories determined total iron content in silicon metal sample by using flame atomic absorption spectrometry.

Determinação direta de Ca, Mg, Mn e Zn em amostras de leite de búfala da Ilha de Marajó por espectrometria de absorção atômica com chama (FAAS)

This work proposes an analytical procedure for direct determination of calcium, magnesium, manganese and zinc in buffalo milk by flame atomic absorption spectrometry (FAAS). Samples were diluted with a solution containing 10% (v/v) of water-soluble tertiary amines (CFA-C) at pH 8. For comparison, buffalo milk samples were digested with HNO3 and H2O2. According to a paired t-test, the results obtained in the determination of Ca, Mg, Mn and Zn in digested samples and in 10% (v/v) CFA-C medium were in agreement at a 95% confidence level. The developed procedure is simple, rapid, decrease the possibility of contamination and can be applied for the routine determination of Ca, Mg, Mn and Zn in buffalo milk samples without any difficulty caused by matrix constituents, such as fat content, and particle size distribution in the milk emulsion.

Determinação de Cd e Pb: avaliação de sedimentos do Rio Jundiaí - SP e Ribeirão Piraí - SP e lodo proveniente de uma estação de tratamento de esgotos

Jundiaí river is the main stream in the Jundiaí Hydrographic Basin and its water is not considered safe for public supply. The water problem is getting worse with the development of the region. The Pirai stream, have been one of the last potable water resource. With the purpose of investigating the sediment quality, due to its influence on the water quality, bioavailable and total Cd and Pb were determined using TS-FF-AAS. Total Cd and Pb up to 2.47 and 24.7 µg g-1 were measured, respectively. The wastewater sludge showed concentrations of 4.01 and 171 µg g-1, for the same metals.

Development of a flotation method for preconcentration-separation of trace amounts of some metal ions in plant tissues prior to their FAAS determinations

An efficient flotation method based on the combination of flame atomic absorption spectrometry (FAAS) and separation and preconcentration step for determination of Cr3+, Cu 2+, Co2+, Ni2+, Zn2+, Cd 2+, Fe3+ and Pb2+ ions in various real samples by the possibility of applying bis(2-hydroxyacetophenone)-1,4-butanediimine (BHABDI) as a new collector was studied. The influence of pH, amount of BHABDI as collector, sample matrix, type and amount of eluting agent, type and amount of surfactant as floating agent, ionic strength and air flow rates i.e. variables affecting the efficiency of the extraction system was evaluated. It is ascertained that metal ions such as iron can be separated simultaneously from matrix in the presence of 0.012 mM ligand, 0.025% (w/v) of CTAB to a test sample of 750 mL at pH 6.5. These ions can be eluted quantitatively with 6 mL of 1.0 mol L-1 HNO3 in methanol which lead to the enrichment factor of 125. The detection limits for analyte ions were in the range of 1.3-2.4 ng mL-1. The method has been successfully applied for determination of trace amounts of ions in various real samples.

Removal of copper(II) from sugar-cane spirits employing chitosan

A method employing chitosan as complexant agent in the removal of copper(II) ions generally present in the Brazilian cachaça samples is herein proposed. The efficiency of this method is attributed to its high capacity of metal cations adsorption, mainly due to presence of hydroxyl and amine groups that can serve as chelating sites. The removal of copper(II) ions from this alcoholic beverage was efficient employing either in column and batch system. The analysis were carried out employing the flame atomic absorption spectrometry and the remaining copper(II) concentrations in the treated cachaça were lower than LOD of FAAS technique.

Validação de metodologia analítica para determinação de mercúrio total em amostras de urina por espectrometria de absorção atômica com geração de vapor frio (CV-AAS): estudo de caso

Mercury is a toxic metal used in a variety of substances over the course history. One of its more dubious uses is in dental amalgam restorations. It is possible to measure very small concentrations of this metal in the urine of exposed subjects by the cold vapor atomic absorption technique. The present work features the validation as an essential tool to confirm the suitability of the analytical method chosen to accomplish such determination. An initial analysis will be carried out in order to evaluate the environmental and occupational levels of exposure to mercury in 39 members of the auxiliary dental staff at public consulting rooms in the city of Araguaína (TO).

Determinação de metais em óleos lubrificantes, provenientes de motores de ônibus urbano, utilizando a FAAS

This work proposed a procedure to examine ashes produced in burning lubricating oils used in public transportation, in Teresina PI. Sulphanilic acid was added to the oil samples, which were burned at 550 °C for three hours and 650 °C for two hours. The ash solutions were analyzed by FAAS and there were significant differences in the metal contents of the waste oil produced from normal car service. The quantification limits in μg g-1 were 5.9 (Fe), 4.4 (Pb), 1.7 (Ni), 2.1 (Cu), and 1.2 (Zn). The results showed positive accuracy and precision with recoveries between 88 and 108%, and RSD lower than 10%.

Determinação de arsênio em amostras da cadeia produtiva de frangos de corte por espectrometria de absorção atômica com forno de grafite

Chicken meat is largely consumed in human nutrition and it is produced in extremely large scale in some countries, including Brazil. In this work graphite furnace atomic absorption spectrometry was used for determination of arsenic in chicken and chicken production-related samples. These samples were digested employing a microwave-assisted procedure in closed vessels using a 7 mol L-1 nitric acid solution plus concentrated hydrogen peroxide. The concentration range of total As determined in chicken production-related samples varied from 1.30 to 29.8 mg kg-1 of As. The detection and quantification limits reached were 0.055 and 0.182 mg kg-1, respectively (n = 15).

Preconcentración y atomización con tubo en la llama para la determinación de Cadmio en agua de mar

A flow injection on-line pre-concentration system coupled to thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) for cadmium determination at sub μg L-1 levels in seawater samples was developed. The on-line system was evaluated by analysing cadmium containing in a synthetic seawater matrix (2.5% m/v NaCl, 0.5% m/v MgCl2 and 0.8% m/v CaCl2). A sample volume of 2 mL allows determining Cd with a detection limits of 30 ng L-1 (3* σblank/slope), pre-concentration factor of 34 and repeatability of 1,8% (calculated as RSD, N=8 and containing 200 ng L-1 of Cd ).

Uso de amêndoas de baru (Dypterix alata) para remoção de Ni(ii) em etanol combustível

The present work describes the sorption potential of Dypterix alata (baru) for removal of Ni(II) in hydrous ethanol. Infrared spectroscopy was used for elucidating possible functional groups responsible for uptaking Ni(II). Sorption studies using Ni(II) standard solutions were carried out in batch experiments as functions of extraction time and pH solution. The Ni(II) was quantified before and after the removal experiments using Flame Atomic Absorption Spectrometry. Furthermore, based on adsorption studies and adsorption isotherms applied to the Langmuir and Freundlich models, it was possible to verify that D. alata presents a high adsorption capacity. The results show that D. alata can be used for removing Ni(II) in ethanol solutions.

Determinación simultánea de Cr, Ni y V en orina mediante et aas

A procedure for the simultaneous determination of Cr, Ni, and V in urine by electrothermal atomic absorption spectrometry (ET AAS) was optimized by factorial design, and performed at a pyrolysis and atomization temperatures of 1300 and 2500 ºC, respectively, using 15 µg de Mg(NO3)2 as chemical modifier. Characteristics mass of 14, 6 and 220 ρg and detection limits of the method of 0.07, 0.38 and 0.75 µg L-1 were obtained for Cr, Ni and V respectively. The methodology was validated using a Liphochek Urine Metals Control sample (Bio-Rad) (P=0.05). The methodology was applied to samples of voluntary Venezuelan people, not environmentally exposed to specific emissions, and results ranging from < LOD-1.1 and 1.3-3.3 µg L-1 was observed for Cr and V, respectively, and not detectable levels for Ni.