Avaliação da 2,2?-biquinolina na separação, preconcentração e determinação de cobre por espectrofotometria de absorção molecular em solução e em fase sólida.

AUTOR(ES)

Alailson Falcão Dantas

DATA DE PUBLICAÇÃO

2004

RESUMO

The present work proposes the evaluation of the cuproine as a reagent for copper extraction, preconcentration and determination using molecular absorption spectrophotometry in solution and in solid phase.In first study, copper (I) cation reacts with cuproine in pH 4.8 forming a pink complex, stable for at least 48 hours, with absorption maximum at 545nm and molar absorptivity e = 6.25x103 L.mol-1.cm-1 against a reagent blank. The reaction occurs in the presence of hydroxylamine, ethanol, Triton-X100 tensoative and EDTA. Copper determination is possible from 0.2 up to 5.0 mg.L-1, with a detection limit of 0.05 mg.L-1. The great advantage of the proposed methodology is the elimination of liquid-liquid extraction step and toxic organics solvents, like dioxane, for dissolve the reagent. In the second study, we have evaluated three methods for copper separation, preconcentration and determination using solid phase spectrophotometry, with modified cuproine / octadecyl reversed phase (C18) for Cu(biq)2+ complex retention, in presence of the hydroxylamine and acetate buffer pH 4.8. For three methods were employed flow-injection analysis (FIA) with artesanal valve injection and flow cells. These systems are faster, sensitivy, cheapness and allow low reagent consumptiom and low waste generation. These three studies have envolved the comparation between cilindric and rectangular cells, so the cilindric cell has been more sensitive, but the cilindric cell has showed fluid leakage because of higer hydrodynamic pressure. It was also evaluate thiourea / acetate buffer and Fe(III) / HCl solutions as eluent for Cu(I) adsorbed in cuproine-C18 solid-phase in the rectangular cell. The acid solution of Fe(III) showed better than thiourea because it presents better elution efficiency and increases the solid-phase lifetime.

ASSUNTO(S)

cuproína c18 fia quimica analitica cupper, cuproine, fia, sfs, solid-phase, c18 cobre efs fase sólida

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