Chemically immobilised enzyme electrodes for hydrogen peroxide determination

Two enzyme electrode systems, based on enzymes (peroxidase and catalase) immobilized (glutaraldehyde) on nylon net, were described for the determination of hydrogen peroxide. The peroxidase enzyme electrode was used in a flow injection analysis (FIA) mode as the working electrode in a three-electrode modified Stelte cell with hexacyanoferrate(II) as a redox mediator at low potential. The problem of electroactive interferents was, thus, removed. The nylon net containing immobilized catalase (converts hydrogen peroxide to oxygen) was placed over the PTFE membrane of an oxygen electrode and used in a dip mode at alkaline pH for analysing waste streams. Neither enzyme system suffered from interferents commonly found in industrial samples where hydrogen peroxide was used (sugars, ethanol and organic acids), or in wastewater samples. Both systems were calibrated for hydrogen peroxide at levels in the range 10 uM-1 mM.