LAUSR

Metal-film electrode development started following and in parallel with mercury-based electrodes, like dropping mercury electrode (DME) and hanging mercury drop electrode (HMDE), the seminal work of 1959 Nobel Prize for chemistry winner J. Heyrovsky. Those electrodes have excellent electroanalytical performance. Scientists developed very sensitive methods for detecting trace level concentrations of basically all metals that form amalgams and furthermore, with the utilization of adsorptive stripping techniques, even those that do not form amalgams. Instead, the accumulation of metallic complexes and subsequent stripping leads to sensitive determinations of metals like Ni, Co and Cr. However, safe handling, measurements, and disposal of liquid mercury require appropriate infrastructure, knowledge and experience. In light of this, metal-film electrodes proved to be a viable and necessary alternative. Although with much less predictable geometry-mercury being in the shape of a smooth spherical droplet-metal film electrodes are still in use and development today. Many metals and alloys have been tested (including mercury film electrode) and have been showing good results for measuring trace levels of toxic metals, various electroactive organic compounds, gases (VOCs), biological assays, etc. Mercury alternatives, for example, gold, silver, iridium, bismuth, antimony, copper, etc., exhibited favourable electroanalytical characteristics, mainly for the determination of some of the most toxic metallic ions and in other aforementioned analytical applications. It has to be also mentioned that many of the metal-film electrodes do not require the removal of oxygen during measurements as mercury electrodes do. This further expedites the measuring procedure and makes it more viable for outdoor and on-site measurements. Coinciding with the research primarily focused on the thinmetal film electrodes was the development of new electroanalytical methods. Basic principles for measurements acquired from initial work with mercury electrodes were translated into the application of metallic films. With the introduction of differential pulse and square-wave voltammetry, the signalOPEN ACCESS