Voltammetric measurements with microelectrodes in low-conductivity systems

It is shown that voltammetric measurements can be made in solutions of low conductivity and low dielectric permitivity by using appropriate microelectrodes, the oxidation of ferrocene in toluene+ acetonitrile being used to explore the behaviour. At high concentrations of acetonitrile, measurements can be made at low or zero concentrations of supporting electrolyte; with decreasing concentration of acetonitrile, increasing concentrations of supporting electrolyte are required to determine the voltammetric curves. Simple corrections for ohmic potential drops in the solution can be applied but the procedures fail for solutions of very low dielectric permittivity, probably because of ion-pair formation near the electrode surface.