Study of the flow dependence of microelectrode and semi-microelectrode voltammetric signals

The systematic experimental study of microelectrode and semi-microelectrode voltammetric and amperometric signal dependence on flow rate in thin-layer, wall-jet and cylindrical flow geometries is presented. It was found that the exponent of flow dependences for micro- and semi-microelectrodes is the same as for macroelectrodes. In the latter case it was in good agreement with theory. For the cylindrical electrode the exponent of experimental flow rate dependence was found to be equal to 1/4, Extrapolation of experimental curves allows a prediction of the microelectrode diameter at which the signal should be independent of the flow rate: 140, 35 and 1 nm for thin-layer, wall-jet and cylindrical detectors respectively. The electrode preparation, cell impedance, current density, influence of electrode radius on measured current, as well as the range of signal independence of flow rate in pulse amperometry are also discussed.