A Chromatographic method to characterize copper-binding ligands

Organic matter in the environment is complex in nature. Through its metal binding activity, it may govern the solubility, mobility and bio-availability of metals in the environment. A chromatographic method to separate the copper-binding ligands in a complex mixture, according to their binding affinity, was developed. The method was tested with model ligands. The order of elution of the ligands follows their Cu-binding affinities as determined by their Cu-binding constants and by measurements with a Cu ion-selective electrode. This confirms the theoretical basis of the method that more strongly binding ligands elute earlier. The scheme was applied to litter organics obtained from two forested sites in the Central Region of Scotland. Both litter organics contained a complex suite of Cu-binding ligands, many of which are strongly Cu-binding. The two sites showed generally similar composition of Cu-binding ligands, probably because of the similarity in vegetation type.