Copper(II) titration of fulvic acid ligand sites with theoretical, potentiometric, and spectrophotometric analysis

Abstract

The Cu(II) titration of a fulvic acid (acid soluble soil organic fraction) is characterized by ion-selective electrode monitoring of Cu(II) and spectrophotometric monitoring of changes in the fulvic acid chromophores. The results indicate the need to recognize the polydisperse mixture character of these naturally occurring organic ligands. The theory of polyelectrolyte titration is developed to provide a common and complete description of both experiments. The titration functions emphasize the stronger binding of Cu(II) by the first sites occupied. Naturally occurring ligands are not homogeneous even after “purification”. © 1980, American Chemical Society. All rights reserved.