Caracterização fluorimetrica da materia organica de origem natural e sua complexação com ions cobre

AUTOR(ES)
DATA DE PUBLICAÇÃO

1995

RESUMO

Marine dissolved organic matter, which has been extracted by adsorption onto SepPak tC18 and, soil fulvic acid processed in the same way, were fractionated by reverse phase high performance liquid chromatography. Based on a stepwise elution gradient, a methodologic procedure was developed using the non-destructive UV-absorption (254 nm) detection system, to further investigate the chromatographic fractions. The organic materiais were fractionated into 4 or 5 chromatographic fractions of differing polarity. FIuorescence spectroscopy was used to investigate some optical properties of the organic materiais, before and after chromatographic fractionation. Conventional emission and excitation, and synchronous excitation spectra were recorded for each sample. For normalization, all results are presented as per unit organic carbon. Emission spectra showed that the soil fuIvic acid fluoresces about 5 times more than the marine sample, and that the extraction procedure results in a loss of some fluorophores classes. The synchronous excitation technique revealed the specificity of some fluorophores: lex/lem 566/584 nm (marine), lex/lem 405/423 nm (soil), lex/lem 317/335 nm (marine). Most of them are present in both organic materiais. FIuorescence quenching experiments showed that there is a loss of strong ligands as a result of the extraction procedure. An adaptation of the modeI described by Ryan and Weber (1982a) to a situation of mutiligands, showed that more than one binding site is less important to the soil fulvic acid than it is for the marine dissolved organic materials. A linear relation was obtained between the minimum fluorescence limit and total ligand concentration per unit organic carbon(CL/TOC).

ASSUNTO(S)

fluorescencia humus

ACESSO AO ARTIGO

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