A TUBULAR GRAPHITE-EPOXY ELECTRODE INCORPORATING HORSERADISH-PEROXIDASE AS A POTENTIOMETRIC SENSOR FOR HYDROGEN-PEROXIDE

A novel potentiometric peroxidase enzyme sensor based on a tubular gra phite-epoxy design is reported for the determination of hydrogen perox ide in an FIA system. The sensor was formed from horseradish peroxidas e (40 mg), graphite (240 mg) and epoxy (780 mg). Hydrogen peroxide, in jected into pH 7, 0.05 M phosphate buffer at 26 degrees C, was determi ned with a linear slope of 45.6 mV/decade in the concentration range 7 .5 x 10(-7) to 5.0 x 10(-5) M. Acceptable reproducibility of 1.2% rela tive standard deviation was obtained in the dow injection analysis. Th e advantages of this sensor are low cost, simple electronic circuit de sign and better selectivity than amperometric sensors and a detection limit comparable with other methods.