Electrochemical techniques are much less complicated for use compared to spectroscopic and chromatographic methods – sample preparation is usually not required. Many of them allow in situ determination, which is important in environmental analysis for continuous monitoring of contaminant concentrations in flow systems such as rivers and oceans. Anodic stripping voltammetry is one of the electrochemical techniques that developed in the late 20th century for the analysis of trace metals.
In the last 60 years, different mercury electrodes (dropping mercury electrode – DME, hanging mercury dropping electrode – HDME, mercury film electrode – MFE) have been used for this kind of measurements, which are dangerous for the environment and living organisms. There is also a problem with handling and storage of mercury. Today, the use of mercury is restricted or even banned. Many electrically conductive materials such as various forms of electrically conductive carbon (pyrolytic graphite – PG, polycrystalline graphite, carbon paste electrode – CPE, glassy carbon electrode – GCE, carbon fibres, etc.), gold, platinum, silver, iridium, etc. have been used to replace mercury as electrode materials, but none of them exhibited excellent electroanalytical properties of mercury electrodes. In 2000, a group of scientists from the Department of Analytical Chemistry (National Institute of Chemistry, Ljubljana) in collaboration with an American partner institution (Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces) introduced bismuth in stripping voltammetry measurements for the detection of heavy metal traces. Then, in 2006, the antimony film electrode was introduced. Recently, the use of copper film electrodes for the detection of selected heavy metal ion traces was investigated by the Department of Analytical Chemistry.
This master’s thesis represents an investigation of properties and applications of various copper electrodes for determination of lead(II) and cadmium(II) ions in low concentrations in water solutions using anodic stripping voltammetry. In my work, copper-film electrodes based on glassy carbon electrodes and screen-printed electrodes (SPE) with carbon working electrode as well as bulk copper electrodes (copper disc electrode, SPE with copper working electrode, copper wire) were investigated. I investigated the influences of various parameters such as medium, copper(II) concentration, time of deposition of copper and analytes and deposition potential on the stability and sensitivity of the electrodes. In the next phase, the parameters were optimised to obtain the best performance of the electrodes, and then their range with linear response, repeatability and limits of detection and quantification (LOD, LOQ) were determined.
The experiments have shown that copper electrodes are very similar to some other already established metal electrodes, for example, antimony and bismuth electrodes. They have good sensitivity and therefore a low detection limit, as well as good repeatability and a broad linear response. Copper as an electrode material is inexpensive and, due to its qualities (the toxicity of most its compounds to organisms is relatively low – it is even used as growth promoter in breeding pigs), it is not problematic to use.
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