Effect of the medium composition on the current of steady state voltammograms of neutral and charged species in dimethylformamide/toluene mixtures

Steady state voltammetric currents of both neutral and charged species obtained at microelectrodes are affected by the medium composition. Experiments carried out in N,N-dimethylformamide (DMF) and toluene/DMF mixtures for the reduction of dicyano(fluoren-9-ylidene)methane (DCN) and the methylviologen cation (MV2+) and for the oxidation of ferrocene (Fc), in the presence of different electrolyte concentrations indicate that both viscosity of the solution and mass transport by migration can have a strong effect on the measured limiting currents. These observations are particularly important in electroanalysis since the appropriate choice of the medium may substantially improve both sensitivity and detection limit of the electrochemical method. (C) 1999 Elsevier Science B.V. All rights reserved.