Voltammetric,potentiometric and amperometric studies with a rotated aluminum wire electrode: Voltammetric behavior of the r.al.e.

A rotated aluminum wire electrode (R.Al.E.) is described for the determination of voltammograms and potentials. An aluminum electrode is highly polarizable both cathodically and anodically. Of all ions tested only hydroxyl and fluoride ions depolarize it anodically at highly negative potentials. In the absence of fluoride it is not a pH electrode, but it is a pOH electrode in the presence of an excess of hydroxyl ions. Fluoride in acid medium and hydroxyl ions yield well defined anodic diffusion currents. In the absence of fluoride or of an excess of hydroxyl ions the potential is ill defined. In acid medium a trace of fluoride (2.10^-5M or 0.4 p.p.m.) causes the potential to become approximately 600 mV more negative than in the absence of fluoride. At a pH greater than j l the potential varies 66 mV per unit change of pH.