Application of the fluorescence quenching titration method to the complexation of copper (II) in the Gironde Estuary (France)

Abstract Quenching of fluorescence emission by the Cu 2+ ion is measured in five samples from the Gironde Estuary (France). Non-linear regression analysis allows us to calculate from experimental data the values of C L (complexing capacities or total ligand concentrations), K (conditional stability constants) and I ML (residual fluorescence at the end of the titration). The results obtained on the Gironde estuarine samples indicate that C L values are very low ( K values decrease from upstream to downstream. The relatively high values of I ML are an indication that much of the organic fluorescing matter does not bind to Cu 2+ .