THE COMPLEXATION OF MARINE AND TERRESTRIAL ORGANIC MATERIALS WITH COPPER-(II) IONS AS DETERMINED BY FLUORESCENCE QUENCHING

Copper complexation parameters, e.g., conditional stability constant ( K') and ligand concentration (CL), were obtained for marine DOM and so il fulvic acid (SFA). Complexometric titrations using Cu(ll) as the ti trant were monitored by fluorescence quenching and data treatment was performed using a two-binding site model. The marine DOM was isolated by partitioning onto tC18 Sep-Pak cartridges and followed by a reverse phase-high performance liquid chromatography fractionation. The SFA w as investigated before and after receiving the same treatment as the m arine sample. The results show that there is a loss of ligands with hi gh affinity for copper as a result of the Sep-Pak treatment on the SFA . The Sep-Pak processed SFA ligands are associated with fluorophores w ith excitation wavelength at 350 nm. The more polar chromatographic fr actions have higher values of CL/TOC, obeying a linear relation. A lin ear relation was also observed between total quenching (100-I-ML and n ormalised CL values (CL/TOC).