Evaluation of operational stability of Prussian blue- and cobalt hexacyanoferrate-based amperometric hydrogen peroxide sensors for biosensing application

The stability of Prussian blue (PB)-based amperometric sensor for hydrogen peroxide detection has been investigated. It was shown that a relatively fast inactivation of the sensor in pH 7.3 solution proceeds during continuous electrocatalytic reduction of hydrogen peroxide at a controlled potential of 0.0 V vs. Ag/AgCl with the first-order rate constant of 1.2×10−2 and 2.8×10−2 min−1 for 0.20 and 0.74 mM of peroxide, respectively. In pH 5.5 buffer solution, the inactivation proceeds approximately two orders of magnitude slower. Cobalt hexacyanoferrate based sensor has been shown to be more stable for electrocatalytic reduction of hydrogen peroxide under same conditions. For 0.74 mM of peroxide, the inactivation of this sensor proceeds with a first-order rate constant of 3.3×10−3 min−1 in pH 7.3 solution at 0.0 V, i.e., ca. 8.5 times slower compared to Prussian blue sensor. The suitability of both sensors for biosensing application is discussed.