Enhancing the sensitivity of potential step voltammetry using chemometric resolution

Abstract

Enhancing the sensitivity of analytical methods by improving the signal quality is a universal goal in analytical chemistry. In analytical electrochemistry systems, the double layer charging current has been an obstacle to the accurate measurement of the faradaic current despite theoretical and experimental efforts. In this study, a method for sensitivity enhancement for potential step voltammetry is developed using chemometric resolution. Trilinear decomposition is used to extract the net faradaic current and double layer charging current directly from the data matrix of the decaying curves measured at different potentials. The feasibility of the method is proven using simulated data and further validated by two experimental datasets of diffusion and adsorption control reactions. Compared with the conventional approach that records the current data at a later pulse time, the voltammogram of the extracted net faradaic current is an ideal sigmoid curve with a horizontal baseline, even for the samples of very low concentration. More importantly, the analytical sensitivity can be greatly improved when the net faradaic current is used for quantitative determination.