Operational stability of amperometric hydrogen peroxide sensors, based on ferrous and copper hexacyanoferrates

Abstract

Hydrogen peroxide sensors, based on Prussian blue (PB) and copper hexacyanoferrate (CHCF), were prepared and tested for operational stability under variety of conditions. PB-based sensors showed low stability, when operated in a cathodic manner at an applied electrode potential of 0.0 or 0.2 V vs. Ag/AgCl reference electrode, especially in pH=7.3 solution, as compared to pH=5.2 solution. An initial sensitivity of ca. (1–3)×10 −6 A mm −2 mM −1 for PB-based sensors drops up to 60% or 85% by repeating use of them in obtaining calibration graphs up to 12 mM H 2O 2 at pH=7.3 and 5.2, respectively. A better operational stability was observed for these sensors, operated in an anodic manner at E=0.6 V. Contrary, CHCF-based sensors showed sufficient high stability, when operated in a cathodic manner at E=0.0 or −0.2 V. A drop of sensitivity of only a few percent was observed for CHCF-based sensors under similar conditions.