COMPARISON OF CARBON-PASTE ELECTRODES MODIFIED WITH NATIVE AND POLYETHYLENE-GLYCOL DERIVATIZED HORSERADISH PEROXIDASES FOR THE AMPEROMETRICMONITORING OF H2O2

Horseradish peroxidase (HRP) has been chemically derivatized with meth oxypolyethylene glycol (mPEG). The derivatization has been proved by s dium dodecyl sulfate (SDS) and capillary electrophoresis. The derivati zed HRP is mixed into carbon paste, and amperometric monitoring of hyd rogen peroxide studied in the pH range between 4 and 8. It is found th at derivatization of HRP with mPEG reduces the electrode response for hydrogen peroxide based on direct electron transfer between electrode and peroxidase. An improved operational stability is, however, exhibit ed by mPEG-HRP-based carbon paste electrodes.