Extração em fase sólida de níquel em amostras aquosas e determinação por espectroscopia de reflectância difusa

• Autor(a) principal: Soares, Aline Rodrigues
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2065
• topic: Reflectância difusa; Níquel; Extração em fase sólida; Reflectance spectroscopy; Nickel; Solid phase extraction; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA

This work aimed at the development and adaptation of a new methodology based on solid phase extraction associated with diffuse reflectance spectroscopy for determination of trace levels of nickel in aqueous samples. The proposed extraction technique involves complexation of Ni2+ ions in aqueous solution on the surface of a solid matrix (naphthalene) saturated with a suitable complexing reagent (dimethylglioxime), forming a pink complex, which corresponds to nickel(II) dimethylglyoximate. This complex impregnated in the solid phase was directly examined by UV-VIS diffuse reflectance spectroscopy, allowing the determination of Ni2+ ions present in aqueous samples. Ideal conditions of precipitation and saturation as mass of the complexing agent, time of contact of Ni2+ solution with the solid phase and pH of Ni2+ solution were evaluated in order to optimize the process. The effect of ions Cd2+, Cu2+, Mn2+, Fe3+ and Co2+ on the determination of Ni2+ by the proposed method was evaluated. Ions Fe3+ and Cu2+ cause a diversion of the analyte signal in both analyzed concentrations, whereas Cd2+, Mn2+, and Co2+ only interfere in the determination of Ni2+ when present in high concentrations. Analytical parameters such as selectivity, linearity, precision, accuracy and limits of detection and quantification were evaluated, indicating that the proposed method is efficient, simple and fast, allowing satisfactory results in the determination of nickel in aqueous samples and thus the validation the developed method. Moreover, solid phase extraction associated with diffuse reflectance spectroscopy showed higher sensitivity than the conventional colorimetric methods, with limits of detection and quantification around 4.3 and 5.7 µg L-1, respectively.