Peroxidase enzyme sensor for on-line monitoring of disinfection processes in the

Abstract

For desirable environmental reasons, peroxides have replaced halogenated substances for disinfection purposes in the food and beverage industry. However, cost issues and the requirement to remove these agents completely after disinfection necessitate simple, low-cost and sensitive test methods with a wide dynamic range and on-line capability. The development and performance of such a method is detailed here. Low-cost peroxide sensors were fabricated using a single deposition procedure, in which horseradish peroxidase enzyme and dimethylferrocene mediator were entrapped within a cellulose acetate membrane, over the working electrode area of a screen-printed three-electrode assembly. Optimum performance was obtained using HRP and DMFc loadings of 25 U and 0.03 μmol per electrode, respectively, and a mean cellulose acetate molecular weight of 37000. The device had a detection limit of 49.5 μM hydrogen peroxide and mean RSD values of 21% across the concentration range 49.5–368 μM. In laboratory studies the sensor was shown to have a stability of ≥4 d in continuous flow-mode maintaining an accuracy of ±16% that was considered acceptable for the intended on-line monitoring of the disinfection process. In a field study, it was successfully used on-line within a flow-cell to measure peroxide levels during disinfection of an industrial fermentation vessel.