Substrate-purging enzyme electrodes. Peroxidase/catalase electrodes for H2O2 with an improved upper sensing limit.

A substrate-purging enzyme electrode carrying a sensing enzyme and a substrate-purging catalyst on its surface is proposed and was examined theoretically and experimentally. Since the substrate-purging catalyst partially consumes the substrate without consuming a cosubstrate, the sensitivity of the enzyme electrode is lowered while the maximum response remains unchanged leading to a raising of the upper sensing limit. Thus, by coating it with a cross-linked film of catalase and albumin, the upper sensing limit of a peroxidase-incorporated polypyrrole membrane electrode as an H2O2 sensor was raised by approximately 2 orders of magnitude.