Study of acid-base properties of fulvic acids using fluorescence spectrometry and multivariate curve resolution methods

Samples of fulvic acids obtained from cultivated calcareous soils are analyzed using acid-base titrations with spectrofluorimetric detection. Observed changes in both synchronous and emission spectra of fulvic acids when pH is changed are explained in terms of a limited number of fluorescent contributions each defined by its specific fluorescent spectrum and a concentration profile (species distribution) recovered from the multivariate curve resolution analysis of experimental data. Information on equilibrium is estimated from concentrations of the acid-base species.