Chemically immobilised enzyme electrodes for hydrogen peroxide determination

Abstract

The use of peroxidase and catalase in electrochemical sensors for hydrogen peroxide is reported. The enzymes are chemically immobilised on nylon net. The peroxidase enzyme electrode is used in a flow injection analysis (FIA) mode as the working electrode in a three-electrode modified Stelte cell with hexacyanoferrate(II) as the redox mediator in a phosphate buffer carrier stream. The low potential used (– 100 mV versus silver-silver chloride) helps to offset the effect of redox-active interferents. The catalase enzyme is used in conjunction with a Yellow Springs Instruments Model 5739 oxygen electrode and has been studied in the dip mode at high pH. The two electrode systems can be calibrated between <10^–5 and >10^–3M hydrogen peroxide and do not suffer from interference by many of the components commonly found either in industrial samples where hydrogen peroxide is employed, or in wastewater samples.