Potencialidade do vermelho de Alizarina S impregnado em resinas para separação e pré-concentração de Cu, Zn e Mn em matrizes salinas.

AUTOR(ES)

Anibal de Freitas Santos Júnior

DATA DE PUBLICAÇÃO

2001

RESUMO

The flame atomic absorption spectrometric (FAAS) determination of trace metal ions in high saline samples, such as seawater and brine, is difficult due to various factors, particularly the low level of metal content and the high salt content of the matrix. Thus, trace determination in saline solutions always needs a prior separation and preconcentration methods. The aim of this work was to explore the possibility of the application of a chelating resin obtained by modification of Amberlite XAD-7 and an anion-exchanger Dowex 1X8?50 with Alizarin Red S for manganese, copper and zinc separation and preconcentration in saline matrices. In order to obtain quantitative recoveries of metal ions, various experimental parameters such as pH, shaking time, sample volume, amounts of solid phase, effects of concomitants, capacity and cations desorptions from solid phases were optimized. For the XAD-7/VAS system, Mn, Cu and Zn were quantitatively retained, in the pH range 8.5-10.0, by using 0.50 g of solid phase, stirring time of five minutes and a total mass up to 200 mg of each cation. The sorbed elements were subsequently eluted with 5 mL of 3 mol L-1 HNO3, with recovering over 95%, and a fifty-fold preconcentration factor for to Zn and a ten-fold preconcentration factor for Mn and Cu was obtained. For Dowex 1X8?50/VAS system, Cu and Mn were quantitatively retained in the pH range 8.1 to 9.0, and Zn pH 8.1, by using 0.75 g of solid phase, ninety minutes of stirring time and a total mass up to 50 mg of each cation. The sorbed elements were subsequently eluted with 20 mL of 2 mol L-1 HNO3, and a five-fold preconcentration factor to Cu and Zn was obtained.The procedures were used to the determination of Mn, Cu and Zn in physiologic solutions and seawater samples, from Salvador-Bahia. The analyte addition technique was used and the recoveries obtained revealed that the proposed procedure shows good accuracy and precision.

ASSUNTO(S)

pré-concentração espectrometria atômica matrizes salinas quimica analitica

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