Estimation of the kinetics of anion transfer across the liquid/liquid interface, by means of Fourier transformed square-wave voltammetry

A novel method of Fourier transformed square-wave voltammetry (FT-SWV) in combination with thin-film modified electrode was employed to investigate the kinetics of anion transfer across the liquid/liquid interface using a conventional three-electrode arrangement. Other than traditional SWV in which currents are sampled only at the end of each pulse, FT-SWV continuously collects the current response and then transforms it into frequency domain. Even harmonic frequencies, which are derived from the faradaic current response, will emerge in the power spectrum. The profile of the even harmonic power spectrum is parabolic and shows a maximum at a certain frequency. The maximum and the corresponding frequency are equivalent to the well-known “quasireversible maximum” and “critical frequency” (fmax) in traditional SWV, respectively. The rate constant and ion transfer coefficient α can be estimated by the obtained fmax. Compared with traditional SWV, FT-SWV is much simpler and faster in ion transfer kinetics estimation.