The nature of voltammetric waves of copper complexes with dimethylglyoxime in ammonia and borate buffer solutions

The voltammetric and adsorptive characteristics of the Cu-DMG complexes in a wide range of Cu concentration (from 5 x 10(-8) M to 1 x 10(-3) M) have been investigated in ammonia and borate buffer. Evaluation of the electrode process included the examination of the effect of Cu, DMG, buffers, ethanol and Triton X-100 concentration, buffer capacity and ionic strength, pH and instrumental parameters. The adsorption phenomena were observed by direct current, linear scan, pulse and alternating current polarography and voltammetry. At high Cu concentration the additional effects such as spikes on the pulse and linear scan voltammetric curves as well as maxima and erratic behavior on the direct current polarograms were observed. From the voltammetric and the potentiostatic transient studies it has been found that these effects are caused by the nucleation and condensation processes. From the bulk electrolysis and microelectrolysis results it follows that the Cu-DMG complex is reduced with participation of two electrons and no proof has been found that in the presence of a Cu-DMG complex a catalytic hydrogen wave is formed. The adsorptive properties of the Cu-DMG complex can be utilized for sensitive determination of Cu traces (from 1 x 10(-7) M to ca. 1 x 10(-5) M Cu) or for simultaneous determination of Cu, Ni and Co by differential pulse polarography or linear fast sweep polarography.