Electrochemistry of copper dithiocarbamate complexes in a conventional electrochemical cell

Electrochemistry of copper dithiocarbamate complexes in a conventional electrochemical cell 

Examination of cyclic voltammograms in acetonitrile-water mixtures used in chromatography demonstrate that excellent electrochemical responses for Cu(dtc)2 can still be obtained in the presence of 30% water. However, solubility of the Cu(dedtc)2 and Cu(pydtc)2 complexes decrease as the water concentration increases and the use of water content higher than 30% may result in precipitation of these complexes. With 30% water, up to 4 x 10 M concentrations of Cu(dedtc)2 can be used, but with Cu(pydtc)2, solubility is limited to approximately 4X 10-5 M 

As an alternative to using the pre-prepared Cu(dtc)2 complex, 1 2 mixtures of copper nitrate and ligand produce electrochemical curves essentially the same as that obtained with the prepared complex. In the presence of a considerable excess of the ligand, Cu(dtc)2 formation is extemely rapid. However, under these conditions, waves due to the oxidation of ligand [58,65,66] mask the Cu(dtc 2 oxidation process. Thus, with a large excess of ligand, only the Cu(dtc)2 reduction wave could be used analytically in a conventional cell. 

When reverse-phase liquid chromatography is used with electrochemical detection in a flowing solution, a buffer is usually present in the mobile phase. The buffer itself should be electroinactive and not interfere with the determination of copper. Instead of using 30% water (0.2 M NaNOa), a suitable aqueous component would be say 30% wa- 

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