Square-wave anodic stripping voltammetry of Zn(II) as a method for probing instabilities at a glassy carbon mercury film microelectrode

Square-wave anodic stripping voltammetry (SWASV) has been used to characterize spontaneous changes in the voltammetric response of 50 ppb Zn(II) in 10 mM KNO3/10 mM HNO3 at 10 μm diameter glassy carbon mercury film microelectrode. The mercury film microelectrode was prepared by ex situ deposition of Hg(II) with the film thickness approaching the diameter of the electrode. A change from electrochemically reversible to irreversible behavior is attributed to the morphology of the mercury film on the carbon electrode. Similar changes in the Zn(II) SWASV signal can be induced at a more conventionally sized 3 mm diameter glassy carbon mercury film electrode by forced convection, but in quiescent solution the mercury film remains stable.