Uso de imagens digitais e ferramentas quimiométricas para identificação e determinação de Cr (VI) em solos contaminados
The determination of toxic metals in soils is an important factor to access their quality or identify possible contamination. The element Cr has double feature: Cr (III) is essential for human beings and Cr (VI) is toxic. In this context, the aim of this work is to propose a simple test for the dete...
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Universidade Federal de São Carlos
2012
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ftunivfsaocarlos:oai:repositorio.ufscar.br:ufscar/6523 2023-05-15T13:46:17+02:00 Uso de imagens digitais e ferramentas quimiométricas para identificação e determinação de Cr (VI) em solos contaminados Use of digital images and chemometric tools for the identification and determination of cr (vi) in contaminated soils Oliveira, Luciana Fontes de Pereira Filho, Edenir Rodrigues http://lattes.cnpq.br/3394181280355442 http://lattes.cnpq.br/1848439223921790 2012-03-23 application/pdf https://repositorio.ufscar.br/handle/ufscar/6523 por por Universidade Federal de São Carlos BR UFSCar Programa de Pós-Graduação em Química - PPGQ OLIVEIRA, Luciana Fontes de. Use of digital images and chemometric tools for the identification and determination of cr (vi) in contaminated soils. 2012. 89 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/6523 Acesso Aberto Química analítica Quimiometria Crômio Imagens digitais Solos CIENCIAS EXATAS E DA TERRA::QUIMICA Dissertação 2012 ftunivfsaocarlos 2023-03-11T20:59:50Z The determination of toxic metals in soils is an important factor to access their quality or identify possible contamination. The element Cr has double feature: Cr (III) is essential for human beings and Cr (VI) is toxic. In this context, the aim of this work is to propose a simple test for the determination of Cr (VI) in soil samples using digital images and chemometric tools. The samples used in this project were collected at Maritime Antarctica, around the Comandante Ferraz Antarctic Station (a Brazilian scientific station). Alkaline medium was used to extract Cr (VI) of the samples and the chromogenic reagent was added to color development. To obtain the digital images, the extracts were placed in Petri dishes and a multifunction printer was employed. The results were compared with those calculated by molecular absorption spectrometry. For the images, the MatLab program version R2009a was used to obtain the mean values of colors R, G, B, H, S, V, r, g, b and L, and the Pirouette 4.0 program to the chemometric tools application. The digital images were evaluated in order to be applied for the proposition of models of classification and supervised calibration method PLS (Partial Least Squares). Two types of preprocessing were used to calculate PLS models: autoscaled and mean centered. For the calibration set was used the blanks and standards in a total of 52 solutions and as validation set was used 44 solutions (samples replicas). The model using the mean centered preprocessing was better. Furthermore, when the real values were compared with the predicted the coefficient of correlation was 0,991. It is evident that the proposed method is a simple strategy with low cost for the detection of Cr (VI) in soil samples. Furthermore, the images have great potential to be applied for classification models. The Pb determination using digital images was also tested, but problems with the solutions pH did not permit the application of the methodology for real samples. Universidade Federal de Sao Carlos A determinação ... Thesis Antarc* Antarctic Antarctica Repositório Institucional Universidade Federal de São Carlos (RI UFSCar) Antarctic Ferraz ENVELOPE(-64.117,-64.117,-65.117,-65.117) Solos’ ENVELOPE(42.706,42.706,64.750,64.750) |
institution |
Open Polar |
collection |
Repositório Institucional Universidade Federal de São Carlos (RI UFSCar) |
op_collection_id |
ftunivfsaocarlos |
language |
Portuguese |
topic |
Química analítica Quimiometria Crômio Imagens digitais Solos CIENCIAS EXATAS E DA TERRA::QUIMICA |
spellingShingle |
Química analítica Quimiometria Crômio Imagens digitais Solos CIENCIAS EXATAS E DA TERRA::QUIMICA Oliveira, Luciana Fontes de Uso de imagens digitais e ferramentas quimiométricas para identificação e determinação de Cr (VI) em solos contaminados |
topic_facet |
Química analítica Quimiometria Crômio Imagens digitais Solos CIENCIAS EXATAS E DA TERRA::QUIMICA |
description |
The determination of toxic metals in soils is an important factor to access their quality or identify possible contamination. The element Cr has double feature: Cr (III) is essential for human beings and Cr (VI) is toxic. In this context, the aim of this work is to propose a simple test for the determination of Cr (VI) in soil samples using digital images and chemometric tools. The samples used in this project were collected at Maritime Antarctica, around the Comandante Ferraz Antarctic Station (a Brazilian scientific station). Alkaline medium was used to extract Cr (VI) of the samples and the chromogenic reagent was added to color development. To obtain the digital images, the extracts were placed in Petri dishes and a multifunction printer was employed. The results were compared with those calculated by molecular absorption spectrometry. For the images, the MatLab program version R2009a was used to obtain the mean values of colors R, G, B, H, S, V, r, g, b and L, and the Pirouette 4.0 program to the chemometric tools application. The digital images were evaluated in order to be applied for the proposition of models of classification and supervised calibration method PLS (Partial Least Squares). Two types of preprocessing were used to calculate PLS models: autoscaled and mean centered. For the calibration set was used the blanks and standards in a total of 52 solutions and as validation set was used 44 solutions (samples replicas). The model using the mean centered preprocessing was better. Furthermore, when the real values were compared with the predicted the coefficient of correlation was 0,991. It is evident that the proposed method is a simple strategy with low cost for the detection of Cr (VI) in soil samples. Furthermore, the images have great potential to be applied for classification models. The Pb determination using digital images was also tested, but problems with the solutions pH did not permit the application of the methodology for real samples. Universidade Federal de Sao Carlos A determinação ... |
author2 |
Pereira Filho, Edenir Rodrigues http://lattes.cnpq.br/3394181280355442 http://lattes.cnpq.br/1848439223921790 |
format |
Thesis |
author |
Oliveira, Luciana Fontes de |
author_facet |
Oliveira, Luciana Fontes de |
author_sort |
Oliveira, Luciana Fontes de |
title |
Uso de imagens digitais e ferramentas quimiométricas para identificação e determinação de Cr (VI) em solos contaminados |
title_short |
Uso de imagens digitais e ferramentas quimiométricas para identificação e determinação de Cr (VI) em solos contaminados |
title_full |
Uso de imagens digitais e ferramentas quimiométricas para identificação e determinação de Cr (VI) em solos contaminados |
title_fullStr |
Uso de imagens digitais e ferramentas quimiométricas para identificação e determinação de Cr (VI) em solos contaminados |
title_full_unstemmed |
Uso de imagens digitais e ferramentas quimiométricas para identificação e determinação de Cr (VI) em solos contaminados |
title_sort |
uso de imagens digitais e ferramentas quimiométricas para identificação e determinação de cr (vi) em solos contaminados |
publisher |
Universidade Federal de São Carlos |
publishDate |
2012 |
url |
https://repositorio.ufscar.br/handle/ufscar/6523 |
long_lat |
ENVELOPE(-64.117,-64.117,-65.117,-65.117) ENVELOPE(42.706,42.706,64.750,64.750) |
geographic |
Antarctic Ferraz Solos’ |
geographic_facet |
Antarctic Ferraz Solos’ |
genre |
Antarc* Antarctic Antarctica |
genre_facet |
Antarc* Antarctic Antarctica |
op_relation |
OLIVEIRA, Luciana Fontes de. Use of digital images and chemometric tools for the identification and determination of cr (vi) in contaminated soils. 2012. 89 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/6523 |
op_rights |
Acesso Aberto |
_version_ |
1766239751241728000 |