Effect of Cu(II) on the electrochemically initiated reaction of thiols with N, N-diethyl- p-phenylenediamine: methodology for the indirect voltammetric determination of Cu(II).

The effect of Cu(II) on the determination of homocysteine via its electrochemically initiated reaction with N, N-diethyl-p-phenylenediamine is examined. The presence of copper inhibited the detection process for homocysteine owing to a complexation reaction occurring. This provided an indirect route for the sensitive and selective determination of Cu(II), which produced a linear response over the range from 2.5 to 500 microM and a limit of detection of 2.5 microM. The detection pathway was examined in the presence of metallic and inorganic ions, with negligible interference observed.