Characterization of tetramethylammonium ion binding to fulvic acid molecules by the use of 1H DOSY method.

摘要

Binding of cationic organic molecule, tetramethylammonium ions(TMA+) to dissociated fulvic acid molecules(FA-) of various origins has benn evaluated by using ~1H DOSY method. Chemical shift(σ) together with diffusion coefficient (D) value have been determined as a function of ?, the degree of neutralization of FA molecules. Specific interaction between TMA~+ and moieties of FA- molecules has been revealed, which is dependent of the chemical nature of the FA- samples examined. The results were compared with a PAA~- /TMA~+ system, where TMA+ ions bind to PAA- mainly due to territorial binding mode. 1H DOSY method can characterize the counterion binding to FA molecules.