Chemometrics-Assisted Resolving of Net Faradaic Current Contribution from Total Current in Electroanalytical Methods

Total current in the electroanalytical data is assumed to be consisting of three main constituents: faradaic current, step charging current and induced charging current. Both charging currents can cause an interfering effect on precise determination of faradaic currents, and hence insert direct effects on sensitivity and detection limit of the electroanalytical techniques. Despite the widespread techniques introduced until now, the extraction of the net faradaic current from total current still remains a challenge. By using multivariate curve resolution-alternating least square (MCR-ALS) as a powerful curve resolution-based chemometrics method, a straightforward method has been introduced for resolving faradaic current from the two types of charging currents (step charging current and induced charging current) in single potential step and staircase cyclic voltammetric methods [1]. By simultaneous analyses of the current data matrices for different electrochemical systems, the three sources of current were successfully identified and their contributions in the total signal were easily calculated. We show that the suggested method can be used to estimate the cell-time constant. Also, by monitoring the changes in the net faradaic current as function of the concentration of analyte, one can derive calibration curve at early time of experiment with higher sensitivity comparing to conventional method [2]. Moreover, this method allowed us to investigate the effects of the type of electrode and the nature of supporting electrolyte on the contribution of charging current in total current [3].