Suitability of gold-array ultramicroelectrodes for electrochemical detection in flow systems

Two prototypes of arrays of gold ultramicroelectrodes (Au-UMEA), with 5 and 10 μm UME radii and steady-state response, have been tested as amperometric detectors in flow systems. Three prototypes of polymethyl methacrylate miniaturized flow cells have been especially designed and built for Au-UMEA devices. The performances of the different Au-UMEA/cell combinations have been tested, and the corresponding figures of merit determined by using three catecholamines as model compounds. Best results were obtained with the integration of the electrodes (Au-UMEA, reference and counter) as close as possible in a one-block cell. Moreover, the lifetime of Au-UMEAS is increased as compared with two-block cells. In general, the 5 μm Au-UMEA electrode yields better limits of detection while the 10 μm Au-UMEA covers a wider linear response range.