62 resultados para EDXRF
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Energy dispersive X-ray fluorescence methodology (EDXRF) was used to determine Al, Ba, Ca, Cr, Fe, K, Mn, Pb, Rb, S, Si, Sr, Ti, V, Zn in pottery sherds from seven archaeological sites in the central region of Rio Grande do Sul State, Brazil. The potteries' chemical fingerprints from Ijuí River, Ibicuí Mirim River, Vacacaí Mirim River and Jacuí River were identified. Interactions between sites from the Jacuí River, Vacacaí Mirim River and Ibicui Mirim River could have occurred because some samples from these sites are overlapping in a principal component analysis (PCA) graphic. The pottery provenance could be the same.
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This study aimed to evaluate the chemical elements levels in soil, submitted to different management systems and use by the Energy Dispersive X-Ray Fluorescence Spectrometry - EDXRF. The systems were T1 - agro forestry (SAF), T2 - Native Field (CN), T3 - Native Forest (NM), T4 - Tillage Forest (PF); T5 - conventional tillage system (SPC) and T6 - System tillage (NT). Samples were collected at 0-10 and 10-20 cm, dried and ground for analysis in EDX-720. The soil showed no difference in the average concentrations of chemical elements analyzed in the profiles, but the systems presented different concentrations of metal elements, and T3 had the highest K, Ca and Zn at 0-10 cm and higher contents of K, Ca, Cu, Zn and Mn in the layer of 10-20 cm.
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This article describes a comparison of conventional energy-dispersive X-ray fluorescence (EDXRF) and synchrotron radiation total-reflection X-ray fluorescence (SRTXRF) for Co determination in ruminal fluid from Holstein cow. This element is used as marker for animal nutrition studies. For EDXRF, 200 mu l of the sample were dried on 6.35 mu m Mylar filmat 60 degrees C. The excitation was carried out using an X-ray tube with Mo target and Zr filter operated at 30 kV/ 20 mA. For SRTXRF, 10 mu l of the samplewere pipetted on a Lucite carrier and dried at 60 degrees C. In both the techniques, Ga was used as internal standard and the acquisition time was 200 s. The trueness of both techniques was evaluated through the standard addition method, the recoveries obtained by SRTXRF and EDXRF were 76 and 99%, and the limits of detection, 13 and 240 mu g l(-1), respectively. Copyright (C) 2011 John Wiley & Sons, Ltd.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Dendrochemistry is based on the determination of elements retained in tree rings, which can be useful to characterize environmental occurrences. This work shows elemental mappings obtained by EDXRF of the cross section of a tree stem. The tree is originated from a polluted area in Campinas, São Paulo. Some profiles, as the sulfur one, show variations that can be attributed to external contributions, whereas the silicon one can be inferred to a protection defense natural mechanism. Besides being simultaneous and multielementar, the main advantages here are its performance through a non-destructive sample treatment and the ease of operation of XRF equipments.
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A method for simultaneous determination of Cr, Fe, Co, Ni, Cu, Zn, As e Pb in liquid chemical waste using Energy Dispersive X-Ray Fluorescence (EDXRF) technique was evaluated. A small sample amount (200 mu L) was dried on a 6.35 mu m thickness Mylar film at 60 degrees C and the analyses were carried out using an EDXRF spectrometer operated with an X-ray Mo tube (Zr filter) at 30 kV/20 mA. The acquisition time was 300 s and the Ga element was utilized as internal standard at 25 mg/L for quantitative analysis. The method trueness was assessed by spiking and the detection limit for those elements ranged from 0.39 to 1.7 mg/L. This method is notable because it assists the choice of the more appropriated waste treatment procedure, in which inter elemental interference is a matter of importance. In addition, this inexpensive method allows a non-destructive determination of the elements from (19)K to (92)U simultaneously.
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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Conservação e Restauro
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Dissertação apresentada para obtenção do Grau de Doutor em Conservação e Restauro, especialidade Teoria, História e Técnicas, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
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Dissertação apresentada na Faculdade de Ciências e Tecnologias da Universidade Nova de Lisboa, para obtenção do grão de Mestre em Conservação e Restauro Área de especialização: Vitral
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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Conservação e Restauro