EVOLVING FACTOR-ANALYSIS OF SYNCHRONOUS FLUORESCENCE-SPECTRA OF FULVIC-ACIDS IN THE PRESENCE OF ALUMINUM

The variations observed in synchronous fluorescence spectra of aqueous solutions (pH = 4) of three fulvic acids (fua) upon variation of the concentration of Al3+ were analyzed by evolving factor analysis (EFA). 'rhe three fua samples were extracted from materials present in a pin ewood soil: dry pine needles and the upper and lower soil horizons. Th e presence of Al3+ induces quenching and enhancement of bands in the s ynchronous fluorescence spectra, and concentration constraints are pro posed for the EFA analysis that allow the calculation, on a self-model ing curve resolution basis, of the number of components that show line arly independent variations, their spectra, and corresponding concentr ation profiles. Simulated and experimental data sets of simple known c ompounds (catechol, caffeic acid, salicylic acid, and morin) were also studied as the first validation of the experimental and data treatmen t procedures.