MULTIELECTRODE DETECTION IN VOLTAMMETRY - PART I - A VERSATILE MULTICHANNEL VOLTAMMETRIC INSTRUMENT

A multi-channel voltammetric instrument is described for use with arra ys of micro-electrodes. The instrument can access up to 31 electrodes in voltammetric measurements either independently or in groups (2-31 e lectrodes per group) and works in a simple two electrode like cell mod el, employing only one current-to-voltage converter. Two digital-to-an alog converters were employed to ensure wide flexibility of the potent ial applied to the array. The control of the instrument, the data acqu isition and treatment procedures were automated using an addressable a synchronous interface and a microcomputer running software written in QuickBasic 4.5. An array, containing 31 microelectrodes, embodied in a polyester isolating block, was constructed and employed for evaluatio n of the instrument performance. Each microelectrode was made of a sub -array containing seven copper discs (55 mu m diameter) covered with a mercury film. Two new procedures to obtain voltammetric signals, at a scan rate equivalent to 3.2 V s(-1), are proposed. These procedures a ccess each electrode of the array while they are kept at different pot entials, producing voltammetric pseudo-curves similar to those obtaine d by normal- and differential-pulse voltammetry, Other conventional vo ltammetric techniques such as potential staircase sweep, differential- pulse and anodic stripping voltammetry were also evaluated for use wit h the instrument, showing that the dynamic range of the measurements c an be improved by selecting the number of electrodes to be employed wi thout decreasing the scan rate.