The electrochemical determination of copper directly on an array of microlithographically fabricated iridium ultramicroelectrodes was investigated. Analysis was performed using square wave anodic stripping voltammetry. Experimental parameters such as supporting electrolyte, frequency, and deposition time and potential were optimized to yield reliable signals for copper in the parts-per-billion range. Good linearity was obtained in the 20-100 ppb range. Interference of other metals such as lead, cadmium, zinc, silver and mercury were investigated. The reliability, stability and reproducibility of the signal were evaluated by altering the concentration and deposition time of copper. The surface of the iridium ultramicroelectrodes, which changed during use, was investigated by atomic force microscopy.
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