AMPEROMETRIC IMMUNOSENSORS AND ENZYME ELECTRODES FOR ENVIRONMENTAL APPLICATIONS

Amperometric biosensors can offer a viable, low cost solution to field monitoring in environmental analysis. The rational choice of immobili sation, transduction and biorecognition chemistries is demonstrated in this work to yield improved catalytic and affinity electrochemical bi osensors for environmental applications. Thus, graphite electrodes wit h tyrosinase immobilised in a hydrogel are shown to correlate satisfac torily with the official method for the determination of the phenol in dex in environmental samples with analysis time of about 2 min per sam ple. Secondly, a phosphorylase A-phosphoglucomutaseglucose 6-phosphate dehydrogenase biosensor is demonstrated, that, based on the use of th is three-enzyme cascade and combined with new beta-nicotinamide adenin e dinucleotide (NADH) oxidation mediators, makes it possible to detect phosphate without the addition of any reagent. Thirdly, an immunosens or for atrazine is presented that based on electrochemically 'wired' p eroxidase-labelled atrazine and its competition for the binding sites of immobilised antibodies, reached mu g l(-1) detection limits and sho rt incubation times. (C) 1998 Elsevier Science B.V.