Portal de Periódicos da CAPES

Artigo Acesso aberto Produção Nacional Revisado por pares

BIBTEX RIS

Utilização de eletrodos potenciométricos de amálgama em estudos de complexação de substâncias húmicas

1999; Brazilian Chemical Society; Volume: 22; Issue: 5 Linguagem: Inglês

10.1590/s0100-40421999000500006

1678-7064

Gilberto Abate, Jorge C. Masini,

Environmental Toxicology and Ecotoxicology

Potentiometric amalgam electrodes of lead, cadmium, and zinc are proposed to study the complexation properties of commercial and river sediment humic acids. The copper complexation properties of both humic acids were studied in parallel using the solid membrane copper ion-selective electrode (Cu-ISE). The complexing capacity and the averaged conditional stability constants were determined at pH 6.00 ± 0.05 in medium of 2x10-2 mol L-1 sodium nitrate, using the Scatchard method. The lead and cadmium amalgam electrodes presented a Nernstian behavior from 1x10-5 to 1x10-3 moles L-1 of total metal concentration, permitting to perform the complexation studies using humic acid concentrations around of 20 to 30 mg L-1, that avoids colloidal aggregation. The zinc amalgam electrode showed a subnernstian linear response in the same range of metal concentrations. The Scatchard graphs for both humic acids suggested two classes of binding sites for lead and copper and one class of binding site for zinc and cadmium.