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 obta ined at microelectrodes are affected by the medium composition. Experiments carried out in N,N-dimethylformamide (DMF) and toluene/DMF mixtures for th e reduction of dicyano(fluoren-9-ylidene)methane (DCN) and the methylviolog en cation (MV2+) and for the oxidation of ferrocene (Fc), in the presence o f different electrolyte concentrations indicate that both viscosity of the solution and mass transport by migration can have a strong effect on the me asured limiting currents. These observations are particularly important in electroanalysis since the appropriate choice of the medium may substantiall y improve both sensitivity and detection limit of the electrochemical metho d. (C) 1999 Elsevier Science B.V. All rights reserved.