Electrochemical reduction of the trimethyllead(IV) cation in seawater

A. M. Bond, J. R. Bradbury, G. N. Howell, H. A. Hudson, P. J. Hanna, S. Strother

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The need to distinguish between inorganic and organic forms of lead in seawater has been widely recognized. Electrochemical techniques based on reduction at mercury electrodes or anodic stripping voltammetry have been proposed as methods for determining the various forms of lead. However, detailed investigation of the electrode process for the electrochemical reduction of the trimethyllead cation in seawater show that correct data may not necessarily be obtained with all electrochemical techniques. On the short time scale of polarography the proposed reduction mechanism is: (CH3)3Pb++e(CH3)3Pb+3 Hg→Pb(amalgam)+3 CH3Hg(ads) 3 CH3Hg(ads)+3e→3 CH3Hg- Data show that differential pulse polarography can be used to determine simultaneously inorganic lead and the trimethyllead cation, however, with inverse oxidation experiments involving stripping of lead (amalgam) such as reverse normal pulse voltammetry, substantial modification to the electrode process occurs in the presence of methylated mercury. Anodic stripping voltammetry therefore suffers from substantial interference, when using the: Pb(amalgam)Pb2++2e electrode process for determining the concentration of the trimethyllead cation in seawater.

Original languageEnglish
Pages (from-to)217-228
Number of pages12
JournalJournal of Electroanalytical Chemistry and Interfacial Electrochemistry
Issue number1-2
Publication statusPublished - 23 Sep 1983

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