where the factor A depends on the kinematic viscosity and the ionic
strength of the solution [31]. In contrast to the voltammetry of H+
where no sample contamination risk exists, this might be problemwhen amperometry of OH ions is performed using W electrode
due to tungsten dissolution, and the proposed method is the more
feasible when certain amount of the sample can be sacrificed.
Although this is not the case when voltammetry of OH ion is performed
with Au electrode, as the measured current originates
purely from the OH oxidation, the measurements with the Au electrode
suffer from difficult reproducibility. As demonstrated by Abu-
Rabi et al. [38] voltammetric response of Au electrode is highly
dependent on the electrode pretreatment. It was reported that the
limiting diffusion current of OH oxidation on the gold electrode
may be observed in two potential regions, the lower, 1.1–1.4 V vs.
SCE, and higher region, 1.4–1.6 V vs. SCE. The reason for such behavior
is sought in different types of oxide present on the surface,
namely Au(I) and Au(III) oxide, depending on the electrode treatment.
In addition, the same authors also discussed the effect of
the polarization rate which can affect significantly the linearity of
the jL vs. c(OH) curves [38], which is not the case when W electrode
is used.