Determination of copper speciation in marine waters by competitive ligand equilibration/liquid - liquid extraction: An evaluation of the technique

Abstract

A technique for determining organic complexation of copper using a competitive ligand equilibration coupled with liquid-liquid extraction was evaluated with respect to its applicability in marine waters. Particular attention was paid to the equilibration times required, extractability of naturally occurring organic copper complexes, and consistency with results from electrochemical techniques. In general, it was found that although this approach produces results that agree well with those from other analyses of the open ocean, there are unresolved discrepancies when it is applied to copper analyses in estuarine samples. The ability to use the technique for analysis of a single sample at different competition strengths, or analytical windows, was also examined. In open ocean waters, it was possible to identify two discrete ligand classes with three different windows, although the determined extent of binding did increase with increasing competition strength.