Automated electrochemical analysis with combinatorial electrode arrays

Two combinatorial approaches for rapid automated screening of electrochemic al activity of modified electrode surfaces are described. One approach enab les simultaneous comparison of electrochemical current by fluorescence asso ciated with pH changes that accompany consumption or production of protons at the electrode surface during a redox process. However, this method canno t distinguish small differences in current at differently modified electrod es. A second approach relies on computer-automated, serial measurement of e lectrochemical current at each electrode of a 64-electrode away immersed in a single electrochemical cell. Unlike the fluorescent screen, the second m ethod is capable of distinguishing small differences in current at differen tly modified electrodes, as demonstrated here for gold electrode surfaces c overed with organosulfur monolayers of different chain lengths. The improve d precision of the computer-automated direct electrochemical method enables examination of active zones that have been first identified by less precis e parallel fluorescent screening methods. The direct electrochemical measur ement method can easily be extended to a variety of electrode materials, in cluding fuel cell electrocatalysts and redox storage materials. A complete description of the methodology, hardware and computer program for automated measurement is provided.