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  • Author or Editor: E. Moreira x
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Summary  

Instrumental neutron activation analysis was applied to evaluate the chemical composition of metallic materials, namely iron, steel, silicon and ferrosilicon certified reference materials. As, Co, Cr, Mn, Mo, Ni, V and W concentrations were analyzed in the iron and steel samples whereas 21 elements were determined in silicon and ferrosilicon samples. Accuracy and precision results of about 10% were achieved for most elements, indicating that the technique is suitable for the analysis of metallic materials. Interferences of Cr and Mn in V; Fe and Co in Mn; Co in Fe and Cr in Ti were quantified and only the last one was critical to the analysis of the materials employed in this work.

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Abstract  

Instrumental neutron activation analysis (INAA) was used in the homogeneity study of a Perna perna (Linnaeus 1758) mussel reference material. Simultaneous determination of 15 elements in six bottles of the material, from a total of 171, was performed. The bottles were considered homogeneous for the analyzed elements, at the 95% confidence level, according to the analysis of variance test performed. Elements were also determined in one bottle with five different sample masses for minimum sample intake estimation. Results varied from 50 to 350 mg, depending on the element.

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Abstract  

Homogeneity study is one of the steps in reference material, RM, characterization. Due to its inherent characteristics, Instrumental Neutron Activation Analysis, INAA, is an analytical technique of choice for homogeneity testing. An interesting possibility is the use of complementary gamma ray photopeaks to confirm INAA homogeneity test results. In this study, the use of the complementary gamma ray photopeaks of 110mAg, 82Br, 60Co, 134Cs, 152Eu, 59Fe, 140La, 233Pa (for Th determination), 46Sc and 75Se radionuclides was investigated in the between bottle homogeneity study of a mussel candidate RM under preparation at IPEN–CNEN/SP. Although some photopeaks led to biased element content results, the use of complementary gamma ray photopeaks proved to be helpful in supporting homogeneity study conclusions for the new RM under characterization.

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Abstract  

Instrumental neutron activation analysis was used at a 2-month long isochronous short term stability test performed on a Perna perna mussel candidate reference material. The assessment of the analysis of variance test, as well as, the normalized results to the control temperature showed no systematic changes in the concentration of Ag, As, Br, Co, Cr, Cs, Fe, Eu, La, Na, Rb, Se, Sc, Th and Zn during the test period. The result showed that the candidate reference material may be transported under normal transport conditions without significant changes in composition for the determined elements.

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Abstract  

In Brazil, the use of herbal medicines is very popular due to its immense flora, cultural aspects and to the popular belief that herbs, which are of natural origin, are safe and without undesirable side effects. Aside from that public interest in natural therapies, the use of herbal medicines has increased expressively due to the high cost of synthetic medicines. In this study, elemental compositions of herbal medicines from the species Ginseng, Ginkgo biloba, Centella asiatica, Mulberry and Aloe vera supplied by different suppliers were evaluated by neutron activation analysis. The concentrations of As, Ba, Br, Ca, Cl, Co, Cr, Cs, Fe, Hf, K, Mg, Mn, Na, Rb, Sb, Sc, Th, Zn and some lanthanides were determined in these samples. Comparisons made between the results indicated differences in their elemental contents depending on the plant species, origins of the samples and the age of the leaves. The results also showed that the herbal medicines contain elements such as Ca, Co, K, Fe, Mg and Zn known as essential to humans and for treatment and prevention of diseases. Toxic elements such as Hg, Cd and Cu were not detected. Elements As and Sb were detected in some samples but at very low concentrations at the μg kg−1 levels. Herbal medicine results were also compared to literature values. Biological certified reference material was analyzed for quality control of the analytical results.

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Summary  

The expression of measurement uncertainties in a standardized form is a requirement for result reliability as it imposes implications to the interpretation of analytical results. In this work, sample mass, elemental standard mass, element decay constant and sample and elemental standard activities were identified as the most important uncertainty sources for the relative method of instrumental neutron activation analysis. The contribution of these sources to the expanded standard uncertainty in the concentration of As, Co, Cr, Fe, K, Na, Se and Zn in biological materials of marine origin was assessed and sample activity was identified as the major contribution.

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Abstract  

The Rio Grande reservoir lies southeast of the Metropolitan Area of São Paulo. In order to evaluate if the sediments contain a historical registration of anthropogenic activity, four sediment cores were sampled from the reservoir. In these cores the Hg concentration was determined by the CV AAS technique, major and trace elements by instrumental neutron activation analysis and the sedimentation rates by the 210Pb method. The results obtained for Hg are much higher than expected, showing an anthropogenic contribution. As a general trend, the elemental concentration decreases with depth, indicating recent contamination.

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Abstract  

The increased pollution in the aquatic ecosystem has led to the investigation of toxic elements in sea water by using marine organisms to assess marine pollution from human activities. Among these organisms, the mollusks bivalves have been used as biomonitors since they can accumulate trace elements and other substances, without the occurrence of their death. In this study, Perna perna mussels were transplanted from a mussel farm (reference region) to four sites located in coastal regions of São Paulo State, Brazil, close to anthropic discharge areas. Vanadium was determined in mussel tissues by instrumental neutron activation analysis (INAA). Quality control of V analysis was checked by analyzing biological reference materials and the results obtained were precise and in good agreement with the certified values. Comparisons between the V concentrations obtained in transplanted mussels indicated that those from São Sebastião region, close to an oil terminal presented the highest concentration of this element, during spring.

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Abstract  

Biomonitoring of coastal areas using marine organisms is an attractive approach for studying pollution caused by anthropic discharges. Most of the experiments are based on the collection and analysis of native organisms, but this method has the disadvantage of dealing with many natural variations. In this work, the marine bivalve Perna perna, very abundant in the coast of the State of São Paulo, Brazil, was transplanted from a mussel farm and used for biomonitoring of four sites, situated in coastal regions close to domestic and/or industrial discharges. Hg, Cd and Pb were determined in the transplanted organisms by AAS and As, Ca, Co, Cr, Fe, Na, Se and Zn were determined by INAA.

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Abstract  

Using instrumental neutron activation analysis, the vertical distribution of La, Ce, Nd, Sm, Eu, Tb, Yb and Lu was determined in 3 well dated sedimentary cores collected from Laguna Mar Chiquita, Argentina. Validation of the methodology was done using the Soil 7 (IAEA) reference material. The REE contents vary according to core location and lithological units, depending on the proportion of fluvial terrigenous components in the lake sediments. Lithologies with higher proportion of terrigenous components show higher REE concentrations, suggesting that the dominant REE carrier phase might be a detrital mineral. There is a consistent value of about 1.2 for (La/Yb)N and (LREE/HREE)N ratios for all sediments at the three sites, indicating a slight LREE enrichment in relation to the average shale NASC. Ce/Ce* values are close to 1.0, meaning that Ce behaves similarly to other light REE's.

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