Estudo de procedimentos analíticos para determinação de Cr(III) e Cr(VI) em amostras sólidas.
Autor(a) principal: | |
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Data de Publicação: | 2006 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFSCAR |
Texto Completo: | https://repositorio.ufscar.br/handle/ufscar/6628 |
Resumo: | The legislation is evolving towards the establishment of restrictions to the concentration of Cr(VI), the most toxic redox form of chromium, in solid materials. This aspect has stimulated the development of sample preparation procedures for redox speciation analysis of chromium in solid samples. In the work here described it was studied procedures for Cr(VI) extraction in solid samples using alkaline solutions. Molecular absorption spectrophotometry based on 1,5 - diphenylcarbazide as chromogenic reagent was used for the determination of Cr(VI). The quantification of Cr(III) was carried out by the subtraction of the total chromium concentration and the concentration of Cr(VI). The samples employed were: soils, cements, cementrelated materials, nutritional complements and metallic components. The extractor solution composed by 0.10 mol L-1 Na2CO3 presented good performance for solid samples. Tests of stability of Cr(VI) indicated that reduction of Cr(VI) to Cr(III) did not occur in the adopted extraction conditions, even in the presence of significant amounts of Cr(III). The diphenylcarbazide method presents good sensitivity for the determination of Cr(VI) in extracts, however the presence of organic matter in the soil samples caused interferences. The total chromium concentrations were determined using either FAAS or ICP OES after complete decomposition of the samples. Sample preparation procedure for total chromium determination was implemented according to the type of sample. Cement samples and cement-related materials were decomposed by fusion. On the other hand, all the other samples were microwave-assisted digested using high pressure vessels. The main limitation of the studied procedures is the evaluation of accuracy because of the lack of standard reference materials. |
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Matos, Wladiana OliveiraNóbrega, Joaquim de Araújohttp://lattes.cnpq.br/8833989058164529http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=C747100cbc4ca46-da8f-4793-a4b5-06986faa71022016-06-02T20:36:58Z2007-10-192016-06-02T20:36:58Z2006-03-02MATOS, Wladiana Oliveira. Evaluation of analytical procedures for determination of Cr(III and Cr(VI) in solid samples.. 2006. 93 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2006.https://repositorio.ufscar.br/handle/ufscar/6628The legislation is evolving towards the establishment of restrictions to the concentration of Cr(VI), the most toxic redox form of chromium, in solid materials. This aspect has stimulated the development of sample preparation procedures for redox speciation analysis of chromium in solid samples. In the work here described it was studied procedures for Cr(VI) extraction in solid samples using alkaline solutions. Molecular absorption spectrophotometry based on 1,5 - diphenylcarbazide as chromogenic reagent was used for the determination of Cr(VI). The quantification of Cr(III) was carried out by the subtraction of the total chromium concentration and the concentration of Cr(VI). The samples employed were: soils, cements, cementrelated materials, nutritional complements and metallic components. The extractor solution composed by 0.10 mol L-1 Na2CO3 presented good performance for solid samples. Tests of stability of Cr(VI) indicated that reduction of Cr(VI) to Cr(III) did not occur in the adopted extraction conditions, even in the presence of significant amounts of Cr(III). The diphenylcarbazide method presents good sensitivity for the determination of Cr(VI) in extracts, however the presence of organic matter in the soil samples caused interferences. The total chromium concentrations were determined using either FAAS or ICP OES after complete decomposition of the samples. Sample preparation procedure for total chromium determination was implemented according to the type of sample. Cement samples and cement-related materials were decomposed by fusion. On the other hand, all the other samples were microwave-assisted digested using high pressure vessels. The main limitation of the studied procedures is the evaluation of accuracy because of the lack of standard reference materials.A legislação está se desenvolvendo no sentido de estabelecer restrições à concentração de Cr(VI), espécie redox mais tóxica do elemento cromo, em materiais sólidos. Esse aspecto tem estimulado estudos referentes à etapa de preparo de amostra para análise de especiação redox de cromo em amostras sólidas. Neste trabalho avaliou-se procedimento de extração de Cr(VI) em materiais sólidos utilizando soluções alcalinas. A espectrofotometria de absorção molecular utilizando 1,5 - difenilcarbazida como reagente cromogênico foi empregada para a determinação de Cr(VI) nos extratos. A quantificação de Cr(III) foi realizada pela subtração do teor de cromo total e o teor de Cr(VI). As amostras utilizadas no trabalho foram: solos, cimentos, derivados de cimento, multimisturas e peças metálicas. O extrator 0,10 mol L-1 Na2CO3 apresentou boa aplicabilidade para amostras sólidas. Testes de estabilidade de íons Cr(VI) indicaram que reduções de Cr(VI) a Cr(III) não ocorreram nas condições de extração empregadas, mesmo na presença de concentrações significativas de íons Cr(III). O método da difenilcarbazida é sensível e adequado para a determinação de Cr(VI) nos extratos, contudo a presença de matéria orgânica nas amostras de solo causou interferências. As análises de cromo total foram feitas empregando as técnicas de FAAS e ICP OES após completa decomposição das amostras. O método de preparo de amostra utilizado para a determinação de cromo total variou de acordo com o tipo de amostra, sendo que para amostras de cimento e derivados aplicou-se fusão e para as demais amostras adotou-se procedimento de digestão em forno de microondas com cavidade e frascos fechados. A maior limitação dos procedimentos estudados foi a comprovação da exatidão devido à praticamente inexistência de materiais de referência certificados.Financiadora de Estudos e Projetosapplication/pdfporUniversidade Federal de São CarlosPrograma de Pós-Graduação em Química - PPGQUFSCarBRPreparação de amostra (Química analítica)Especiação química redoxCromo VICIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICAEstudo de procedimentos analíticos para determinação de Cr(III) e Cr(VI) em amostras sólidas.Evaluation of analytical procedures for determination of Cr(III and Cr(VI) in solid samples.info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesis-1-134c8c01d-b96b-428f-acbc-937c5a211684info:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSCARinstname:Universidade Federal de São Carlos (UFSCAR)instacron:UFSCARORIGINALDissWOM.pdfapplication/pdf867642https://repositorio.ufscar.br/bitstream/ufscar/6628/1/DissWOM.pdfa5425baf394bc1447e17847d5fd1c4abMD51THUMBNAILDissWOM.pdf.jpgDissWOM.pdf.jpgIM Thumbnailimage/jpeg8897https://repositorio.ufscar.br/bitstream/ufscar/6628/2/DissWOM.pdf.jpgfd64e7639740858e9cf5057779fd6d12MD52ufscar/66282023-09-18 18:31:10.541oai:repositorio.ufscar.br:ufscar/6628Repositório InstitucionalPUBhttps://repositorio.ufscar.br/oai/requestopendoar:43222023-09-18T18:31:10Repositório Institucional da UFSCAR - Universidade Federal de São Carlos (UFSCAR)false |
dc.title.por.fl_str_mv |
Estudo de procedimentos analíticos para determinação de Cr(III) e Cr(VI) em amostras sólidas. |
dc.title.alternative.eng.fl_str_mv |
Evaluation of analytical procedures for determination of Cr(III and Cr(VI) in solid samples. |
title |
Estudo de procedimentos analíticos para determinação de Cr(III) e Cr(VI) em amostras sólidas. |
spellingShingle |
Estudo de procedimentos analíticos para determinação de Cr(III) e Cr(VI) em amostras sólidas. Matos, Wladiana Oliveira Preparação de amostra (Química analítica) Especiação química redox Cromo VI CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA |
title_short |
Estudo de procedimentos analíticos para determinação de Cr(III) e Cr(VI) em amostras sólidas. |
title_full |
Estudo de procedimentos analíticos para determinação de Cr(III) e Cr(VI) em amostras sólidas. |
title_fullStr |
Estudo de procedimentos analíticos para determinação de Cr(III) e Cr(VI) em amostras sólidas. |
title_full_unstemmed |
Estudo de procedimentos analíticos para determinação de Cr(III) e Cr(VI) em amostras sólidas. |
title_sort |
Estudo de procedimentos analíticos para determinação de Cr(III) e Cr(VI) em amostras sólidas. |
author |
Matos, Wladiana Oliveira |
author_facet |
Matos, Wladiana Oliveira |
author_role |
author |
dc.contributor.authorlattes.por.fl_str_mv |
http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=C747100 |
dc.contributor.author.fl_str_mv |
Matos, Wladiana Oliveira |
dc.contributor.advisor1.fl_str_mv |
Nóbrega, Joaquim de Araújo |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/8833989058164529 |
dc.contributor.authorID.fl_str_mv |
cbc4ca46-da8f-4793-a4b5-06986faa7102 |
contributor_str_mv |
Nóbrega, Joaquim de Araújo |
dc.subject.por.fl_str_mv |
Preparação de amostra (Química analítica) Especiação química redox Cromo VI |
topic |
Preparação de amostra (Química analítica) Especiação química redox Cromo VI CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA |
dc.subject.cnpq.fl_str_mv |
CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA |
description |
The legislation is evolving towards the establishment of restrictions to the concentration of Cr(VI), the most toxic redox form of chromium, in solid materials. This aspect has stimulated the development of sample preparation procedures for redox speciation analysis of chromium in solid samples. In the work here described it was studied procedures for Cr(VI) extraction in solid samples using alkaline solutions. Molecular absorption spectrophotometry based on 1,5 - diphenylcarbazide as chromogenic reagent was used for the determination of Cr(VI). The quantification of Cr(III) was carried out by the subtraction of the total chromium concentration and the concentration of Cr(VI). The samples employed were: soils, cements, cementrelated materials, nutritional complements and metallic components. The extractor solution composed by 0.10 mol L-1 Na2CO3 presented good performance for solid samples. Tests of stability of Cr(VI) indicated that reduction of Cr(VI) to Cr(III) did not occur in the adopted extraction conditions, even in the presence of significant amounts of Cr(III). The diphenylcarbazide method presents good sensitivity for the determination of Cr(VI) in extracts, however the presence of organic matter in the soil samples caused interferences. The total chromium concentrations were determined using either FAAS or ICP OES after complete decomposition of the samples. Sample preparation procedure for total chromium determination was implemented according to the type of sample. Cement samples and cement-related materials were decomposed by fusion. On the other hand, all the other samples were microwave-assisted digested using high pressure vessels. The main limitation of the studied procedures is the evaluation of accuracy because of the lack of standard reference materials. |
publishDate |
2006 |
dc.date.issued.fl_str_mv |
2006-03-02 |
dc.date.available.fl_str_mv |
2007-10-19 2016-06-02T20:36:58Z |
dc.date.accessioned.fl_str_mv |
2016-06-02T20:36:58Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
format |
masterThesis |
status_str |
publishedVersion |
dc.identifier.citation.fl_str_mv |
MATOS, Wladiana Oliveira. Evaluation of analytical procedures for determination of Cr(III and Cr(VI) in solid samples.. 2006. 93 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2006. |
dc.identifier.uri.fl_str_mv |
https://repositorio.ufscar.br/handle/ufscar/6628 |
identifier_str_mv |
MATOS, Wladiana Oliveira. Evaluation of analytical procedures for determination of Cr(III and Cr(VI) in solid samples.. 2006. 93 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2006. |
url |
https://repositorio.ufscar.br/handle/ufscar/6628 |
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por |
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por |
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-1 -1 |
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34c8c01d-b96b-428f-acbc-937c5a211684 |
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info:eu-repo/semantics/openAccess |
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openAccess |
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application/pdf |
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Universidade Federal de São Carlos |
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Programa de Pós-Graduação em Química - PPGQ |
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UFSCar |
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BR |
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Universidade Federal de São Carlos |
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