Postprint version. Published in Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, Volume 123, Issue 2, June 25, 1981, pages 397-407.
NOTE: At the time of publication, the author Geraldine S.P. Ritchie was not yet affiliated with Cal Poly.
The definitive version is available at https://doi.org/10.1016/S0022-0728(81)80514-1.
Variation of the lifetime of a mercury drop with potential was used to determine the pzc of mercury in the presence of soil humic acids and their aluminium complexes. In all cases there was an overall net shift in the pzc in the cathodic direction. Variation in the extent of the shift with pH and concentration indicated greater adsorption of negatively charged species. The shift was smaller in the presence of aluminium humates, probably due to a decrease in the negative charge of the humic acid molecules after complexing. The use of electroanalytical techniques for metal speciation studies in soils and natural water, if humic materials are known to be present, might therefore be limited.
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