MATHEMATICAL ENHANCEMENT OF THE PERFORMANCE OF VOLTAMMETRIC SENSORS

In voltammetry, the current signal is proportional to the concentration of a substance in a solution. Because background currents are typically large, it is useful to employ a differential measurement of the current to reject background current, thus increasing the ratio of signal to background. A differential current, however, in contrast with a diffusion-limited current, may be influenced by kinetic factors. The hypothesis on which this report is based is that the differential current can be treated mathematically, based on a theoretical model to obtain accurate information concerning concentration. To examine this hypothesis, three experimental systems were employed, the reduction of Zn(II) and of Ni(II) at a mercury electrode, and the oxidation of ferrocyanide at a glassy carbon electrode. Normal pulse voltammetry was used as a calibration technique and square wave voltammetry as the differential measurement technique. Data were analyzed by means of the COOL algorithm, employing the model for quasireversible electron transfer. Concentration information obtained as a result of the comparison of the experimental result with the theoretical model was better than that obtained directly from peak height information.