BIOLOGICALLY MODIFIED ELECTRODES AS FIA DETECTORS

Abstract

This chapter describes new amperometric biosensors and measurement strategies for electrochemical monitoring of flowing streams. Special attention will be given to thin-layer devices based on incorporating the biological entity in polishable and robust graphite-epoxy or soft carbon paste matrices, as well as into micropores of reticulated vitreous carbon. The elimination of supporting membranes (diffusional barriers) and the intimate contact between the biological and transducing sites assure very fast response, as desired in dynamic flour systems. Similar advantages accrue from the use of a series flow thinlayer detector with an upstream biological generator and downstream amperometric "collector." The sensory ability of numerous biological entities, including plant tissues, enzymes or microorganisms will be described in connection with these flow detectors. Potential interferences (electroactive and surface-active) are minimized via enzymatic consumption (digestion) at the surface. Additional advantages are achieved from the simultantous immobilization of several enzymes, enzyme/tissue or enzyme/electron acceptor. The FIA operation allows systematic characterization of electrochemical biosensors, compared to manual, batch, testing.