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Avaliação do uso de múltiplas linhas para a determinação de metais por espectrometria de emissão óptica com plasma acoplado indutivamente
(Universidade Federal de São Carlos, 2010-06-11) Schiavo, Daniela; Nóbrega, Joaquim de Araújo; https://lattes.cnpq.br/8833989058164529; https://lattes.cnpq.br/2383204240089779
The aim of this thesis was the evaluation of the use of multiple lines for determination of metals by inductively coupled plasma optical emission spectrometry (ICP OES) with Littrow optical system, Echelle polychromator and CCD solid-state detector. This instrument arrangement allows fast simultaneous measurements of several spectral lines. The combination of more than two emission lines for each element led to advantages as the minimization of systematic errors caused by spectral interferences and matrix effects, improvement of the figures of merit such as limits of detection (LOD) and quantification (LOQ), and better accuracy for determination of metals in water samples. In this work, several spectral lines were combined for the determination of Al, Cd, Co, Cr, Mn, Pb, U and Zn and different operating conditions were evaluated. Afterwards, parameters for evaluation of the calibration model were calculated to select which combination of emission lines provided the best accuracy (lowest values of PRESS Predicted error sum of squares and RMSEP Root means square error of prediction). A total of 63 different combinations of emission lines were evaluated for each element. Lower limits of detection (LOD) were obtained with multiple lines, i. e., 7.1, 0.5, 6.9, 0.042, 12.9, 28.1 and 6.7 μg L-1 (n = 10) for Al, Cd, Co, Cr, Mn, Pb and Zn, respectively, in the presence of concomitants. The LODs obtained for the most intense emission line were 15.9, 0.7, 8.4, 0.074, 22.5, 26.2 and 9.6 μg L-1(n = 10) for these same sequence of elements in the presence of concomitants. The evaluation of the accuracy of the developed procedure was demonstrated using one water certified reference material (Lot#005914 High-Purity Standards), Tomato Leaves (NIST 1573a) and Bovine Muscle (NIST 8414). Based on the figures of merit it can be concluded that the use of multiple lines improved the sensitivity making feasible the determination of analytes according to the target values required for the current environmental legislation for water samples (CONAMA resolution no 357) and this approach can also be employed as a tool to verify the accuracy of an analytical procedure using ICP OES. However, the selection of the emission lines is critically dependent on the matrix complexity and consequently on the resulting spectral environment, and these effects were more pronounced when working with digests of plant and animal tissues.
Variação espacial e temporal de uma taxocenose de caprelídeos (Crustacea: Amphipoda) em um ecossistema subtropical sujeito à poluição por hidrocarbonetos de petróleo
(Universidade Federal de São Carlos, 2010-06-11) Silva, Danilo Balthazar; Tanaka, Marcel Okamoto; https://lattes.cnpq.br/2768658925977757; https://lattes.cnpq.br/9733801046106862
The petroleum demand, as so as the commerce of its derivates, has caused the introduction of these compounds in marine ecosystems. The transportation and the extraction of petroleum cause severe accidents, impacting coastal ecosystems through a lot of ways. Sargassum beds are very abundant and important to the maintenance of ecological processes in coastal regions. In Sargassum beds the infraorder Amphipoda is one of the most abundant taxonomic groups. Some amphipods species are considered important bioindicators of petrogenic pollution. The Amphipoda Caprellidae shows a high species diversity, and some species are considered strong bioindicators of anthropological impacts. Thus, it can be supposed that, given their potential as bioindicators, caprellids significantly respond to an oil pollutants gradient, as so as others amphipods. The São Sebastião Channel is located at the Brazilian southeastern coast. Oil vessels accidents are among the anthropological impacts in that area. The present study has two chapters. The first one brings evidences of caprellids taxocoenosis structure in a gradient of oil pollutants. The second describes a pattern of temporal variation of caprellids trophic groups. The results suggest that petrogenic pollutants affect caprellids species richness and evenness on the studied scales. A significant pattern of temporal variation was observed in the density of detritivores and omnivores. The results indicate a seasonal segregation in the density of the two groups.