Emprego de silica gel ionicamente impressa como extrator em fase sólida em sistema de análise em fluxo para determinação de cobalto por espectrofotometria

• Ano de defesa: 2009
• Autor(a) principal: Fernandes, Fernanda Fantin
• Orientador(a): Tarley, César Ricardo Teixeira
• Banca de defesa: Moreira, Altair Benedito, Siqueira, Maria Elisa Pereira Bastos De
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Alfenas
• Programa de Pós-Graduação: Programa de Pós-Graduação em Ciências Farmacêuticas
• Departamento: Faculdade de Ciências Farmacêuticas
• País: Brasil
• Palavras-chave em Português: Silica gel; Espectrofotometria
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.unifal-mg.edu.br/handle/123456789/280

The present work describes the development of analytical method based on solid phase flow preconcentration of cobalt ions with further determination by spectrophotometry. Modified silica gel with 2-aminoethyl-3- aminobutylmethyldimethoxysilane (AAMDMS) and ionically imprinted with Co2+ ions (ISG) was employed as solid adsorbent. The flow preconcentration system is based on cationic retention of cobalt in a mini-column filled with ISG, with further elution with 0.5 mol L-1 HNO3. The cobalt ions eluted react subsequently with the complexant 1- (2-pyridylazo)-2-naphthol (PAN), forming a green complex detected spectrophotometrically at 575 nm. The optimized conditions were: sample pH (9.2); buffer (amoniacal) concentration of the sample (0.01 mol L-1), surfactant (SLS) concentration (3.0 mmol L-1); flow rate preconcentration (9.0 mL min-1); buffer solution concentration of PAN (0.75 mol L-1); PAN concentration (100 mmol L-1), pH of PAN solution (10.2); length of reaction coil (225 cm), total elution flow rate (7.0 mL min-1). The selectivity of ISG towards cobalt ions was attested by the constant selectivity for K'(KSGI / Kblank), yielding values of 10.9 and 10.2 for (KSGI / K functionalized silica) and (KSGI / Ksilica gel), respectively in the Co2+/Ni2+ system. For the system Co2+/Cu2+ the values were 6.4 and 11.4. Moreover, interference testing was performed by binary solutions containing different cobalt:interferent proportions [1:1, 1:10, 1:100 (m/m)]. The evaluated ions were Ni+2, Cu +2, Fe2+, Pb+2, Cd+2, Mn +2, Zn +2, Cr+3, and except by zinc, in 1:1 proportion no interference was observed. The precision (n=10, repeatability) for the standards 10.0 and 90.0 μg L-1 yield relative standard deviation of 2.63 and 1.5%, respectively. The method showed the respective detection and quantification limits of 0.51 and 1.71 μg L-1 and a preconcentration factor of 7.21. The proposed method was applied in water samples, urine and certified reference material.