EFFECT OF ION-PAIRING ON STEADY-STATE VOLTAMMETRIC LIMITING CURRENTS AT MICROELECTRODES .2. EXPERIMENTAL STUDIES ON CHARGED (BR-, AG+) AND UNCHARGED (COPPER DIETHYLDITHIOCARBAMATE) SPECIES IN TOLUENE

Steady state voltammetric studies on the reduction and oxidation of un charged copper diethyldithiocarbamate, the reduction of silver cations and the oxidation of bromide anions have been performed in toluene at various concentrations of electroactive species and supporting electr olyte (tetrahexylammonium hexafluorophosphate), utilising platinum inl aid microdisk working electrodes. In cases where the supporting electr olyte is in excess, the voltammetric waves are without too much distor tion from IR drop, and the experimental results for the limiting curre nt are consistent with extensive pairing of the electroactive ion with the counter ion of the supporting electrolyte, as well as between the supporting ions themselves. The range of support ratios that can be s uccessfully studied is restricted by the solubility of the supporting electrolyte and by the severe ohmic polarization that is encountered w hen the ionic content is low. Nevertheless, it has been possible to me asure limiting currents over sufficient ranges of electroactive and su pporting electrolyte concentrations to demonstrate that the theory in Part I of this two-part sequence of articles is adequate to interpret the experimental findings. (C) 1997 Elsevier Science S.A.