ANALYSIS OF THE RATE OF DISSOCIATION OF LIGAND COMPLEXES

Copper-humate dissociation data using humic material from different sampling points in the Ogeechee River (Georgia, USA) as measured by Olson et al. are re-analyzed with the newly developed LODA-G2 method for the determination of rate constant distribution functions. The LODA-G2 method is based on an approximation of the local decay function. A smoothing spline procedure is applied to the data in order to account for the experimental error. The appropriate smoothing parameter is obtained on the basis of the generalized cross-validation technique adapted to the present problem. Without data treatment, spurious peaks occur in the distribution functions due to the experimental error. With the present analysis not only the rate constant distribution function but also its confidence interval is found. By considering the confidence intervals, overinterpretation of the results can be excluded. The results obtained are similar to those of Olson et al., indicating that the intuitive smoothing applied by these authors was fairly realistic. The practical implications of the distribution functions found are briefly discussed.