Square wave voltammetry (SWV) is commonly used in electroanalytical
applications to enhance analyte faradaic signals and minimize nonfaradaic
processes. However, little attention is given as to how best use
SWV to minimize faradaic interference signals that arise from redox
species present in solution that have redox potentials that convolute
with that of the analyte. In conventional SWV, a series of current–time
(i–t) transients are collected,
and i is averaged over a specified window of each
transient (potentiostat dependent). This average i is reported against the electrode potential, E.
As the i–t response is governed
by the type of electron transfer reaction under investigation, we
show how by collecting all i–t data and through judicious choice of the current averaging window,
it is possible to enhance the analyte response while at the same time
reducing the interferent signal. We look at three different electron
transfer reactions, fast electron transfer outer sphere, metal electrodeposition/stripping,
and surface-confined proton-coupled electron transfer (PCET) and demonstrate
different i–t behaviors in
SWV, visually aided by the use of 3D i–t–E plots. In the case of PCET quinone-based
voltammetric sensing of pH in the presence of a heavy metal (here
Cu2+), we show that the use of a much earlier current averaging
window (2–10% of the i–t response) results in the pH signal being clearly distinguished from
that of the overlapping heavy metal.