Stripping voltammetric determination of mercury at modified solid electrodes: I. Development of the modified electrodes Original Research Article

The paper describes the development of modified thick film graphite electrodes (TFGEs) for the stripping voltammetric determination of mercury. It is well known that mercury is determined best using gold electrodes. Therefore we have decided to modify the surface of a solid graphite containing electrode so that after the preliminary chemical or electrochemical reduction metallic gold appears in the modified layer on the electrode. Then mercury is deposited electrochemically from the sample solution on the metallic gold and is determined by anodic stripping voltammetry. To this end three different methods for the electrode modification have been chosen: One modified with a gold(III) solution from which gold was reduced chemically using various agents, one modified with a mixture of a gold(III) salt and Nafion and one modified with different insoluble gold(III) complexes. In method 2 as well as in method 3 the gold(III) was reduced cathodically. By virtue of their lifetime, their reproducibility and their sensitivity we preferred the electrodes modified by method 3 using a gold(III)–pyrrolindinedithiocarbamate (PDC) complex. Analytical applications for the mercury determination using this modified electrodes and the efficiency of this procedure will be published in a following paper.