Electrochemical behavior and analytical performance of an iridium-based ultramicroelectrode array (UMEA) sensor

The electrochemical behavior of an iridium-based ultramicroelectrode array (UMEA) sensor was studied by cyclic voltammetry and chronoamperometry. At a ratio of interelectrode distance to electrode diameter of 14, the UMEA maintains the advantageous properties of individual microelectrodes. The analytical performance of the UMEA sensor was investigated using square wave anodic stripping voltammetry (SWASV). Analytical precision was found to be +/- 0.12 mu g L-1 for Ph and +/- 0.14 mu g L-1 for Cd (1 s) based on 50 repetitive measurements of 1.00 mu g L-1 Cd and Pb in a 0.02M acetate solution (pH=4.5). Detection limits below ppb level were obtained for different heavy metals such as Cd, Pb, and Cu. Instrumental parameters were optimized and interferences were investigated. The UMEA sensor was applied to the analysis of heavy metals in river water, and the results were validated by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS).