Extração em fase sólida de zinco(II) e cobre(II) em amostras aquosas e determinação por espectroscopia de reflectância difusa

• Ano de defesa: 2009
• Autor(a) principal: Sousa, Flaviane Aparecida de
• Orientador(a): Neves, Antônio Augusto
• Banca de defesa: Bellato, Carlos Roberto , Reis, César
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Agroquímica
• Departamento: Agroquímica analítica; Agroquímica inorgânica e Físico-química; Agroquímica orgânica
• País: BR
• Palavras-chave em Português: Reflectância difusa; Cobre; Zinco; PAN
• Palavras-chave em Inglês: Diffuse reflectance; Copper; Zinc; PAN
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA
• Link de acesso: http://locus.ufv.br/handle/123456789/2075

The objective of this work was to develop and adapt a methodology based on solid phase extraction associated with the diffuse reflectance spectroscopy for determination of zinc (II) and copper(II) in aqueous samples. The proposed method of extraction involves the complexation of ions zinc(II) and copper(II) in aqueous solution, on the surface of a solid matrix (naphthalene) impregnated with the complex 1-(2- pyridylazo)2-naphthol (PAN), forming colored complex. The complexes formed on the surface of the solid phase were analyzed directly by the diffuse reflectance spectroscopy in the VIS region. The ideal conditions for formation of complex, such as time of contact between the solution of zinc (II) or copper(II) and solid phase and the ideal pH of the solution were optimized for each metal ion separately getting a better response to the time of 60 minutes for both metals. The ideal pH of the solution of zinc ions(II) was 7.5 while for the solution of copper ions(II) the pH was 6.00. We performed the validation of analytical method with the objective of ensuring the reliability of the results by the proposed method. Analytical parameters such as linearity, limits of detection and quantify, selectivity, precision and accuracy were evaluated, obtaining satisfactory results in the determination of zinc (II) and copper (II) in aqueous samples. The study showed that interfering ions Cd2+, Fe3+, Ni2+ and Co2+ significantly interfere in the formation of the complex in solid phase, and therefore required prior to the separation of ions in aqueous samples to be analyzed by the method proposed. The method of solid phase extraction associated with the diffuse reflectance spectroscopy, showed high sensitivity compared to conventional colorimetric methods, obtaining limits of detection equal to 0.042 and 0.068 μmol L-1 (2.75 e 4.32 µg L-1)and limits of quantify equal to 1.39 and 0.416 μmol L-1 (90.98 e 26.44 µg L-1)for zinc (II) and copper(II) respectively, under optimal conditions.