666 resultados para Espectrometria


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Pós-graduação em Ciência dos Materiais - FEIS

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The objective of this study was to compare different resins and determine their matching color with Vita shade, also investigating the possibility of substitution among them and the correlation between the visual and spectrophotometry methods of color selection. The composite resin Tetric N-Ceram® shade A1 was used as light-control and color A4 as dark-control. For each material were prepared five 10 x 2 mm disks. Analyses were performed in a metamerism box by volunteers who ordered the specimens from the lightest to the darkest. The spectrophotometry was carried out using the spectrophotometer Vita Easyshade®. ∆E values were subjected to analysis of variance with 5% significance level. The Fisher exact test showed that there was no color match among the materials and the reference Vita shade. The possibility of substitution among the composites could not be established. The two methods are able to correctly differentiate the control resin A4 as distinct from the other resins shade A2.

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Pós-graduação em Biotecnologia - IQ

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Pós-graduação em Ciência dos Materiais - FEIS

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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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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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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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Due to the large amount of pesticides applied in agriculture, mainly herbicides, there is a growing concern about a possible environmental contamination with these products, including water bodies. Given the above, the aim of the present work was to detect and quantify herbicides through multiresidue analysis in water samples collected in semi-artesian wells and springs in a rural area of the city of Jaboticabal (SP). Samples were collected from 32 wells and 13 water springs, in three different seasons: October 2010, February 2011 and May 2011. Additionally, samples at a residence in the urban area were also collected. Analysis using high performance liquid chromatography coupled to mass spectrometry was performed and herbicides ametryn, amicarbazone, clomazone, diclosulan, diuron, hexazinone, imazapic, imazapyr, isoxaflutole, S-metolachlor, sulfentrazone, sulfometuron-methyl, and tebuthiuron were evaluated. In semi-artesian wells, an incresed quantity of herbicides was found in comparison with the water springs. Among the tested herbicides, hexazinone, imazapyr and sulfentrazone were detected in measurable amounts in accordance with the analytical method applied, while clomazone was the most common herbicide being detected in more than 60% of the samples. Ametryn, diuron and amicarbazone herbicides were also detected. Diclosulan, imazapic, isoxaflutole, S-metolachlor, sulfometuron-methyl, and tebuthiuron were not detected in any sample. Inappropriate use of these products without prior knowledge of the behavior of the soil can lead to groundwaters and water springs contamination, thus an ongoing monitoring of this resource becomes very important.