STUDY OF THE INTERACTION OF A MARINE FULVIC-ACID WITH CU(II) AT LOW CONCENTRATION BY MOLECULAR FLUORESCENCE AND CHEMOMETRICS

The Cu(II) complexation properties of a dilute solution of a marine fu lvic acid sample (mfua) (25 mg/L solution in 0.1 mol/L potassium nitra te at pH=6) were studied by molecular fluorescence spectroscopy. The e mission and the synchronous fluorescence (SyF) modes were used to comp are their advantages and limitations. In the treatment of results, spe ctral data were pre-processed by a self-modeling mixture analysis meth od (SIMPLISMA) to detect different variations (components) in the raw data and to extract the spectra and quenching profiles of these compon ents. These profiles of the quenching provoked by the Cu(II) ion on th e mfua fluorescence were analyzed by the Stern-Volmer method and by a non-linear least squares procedure to obtain the conditional stability constants (K'). The log(K') for the strongest binding sites obtained from the non-linear analysis was 4.52(8) and 5.0(1), respectively from the emission and SyF spectral data. The overall log(K') obtained from the Stern-Volmer analysis was 4.32(7) and 4.42(6), respectively.