Determination of hydrogen peroxide in disinfectant solutions using a biosensor with two antagonist enzymes

The development and characterisation of a new biosensor for hydroperoxides is described, which is obtained by combining an oxygen gas diffusion amperometric electrode and two immobilized enzymes (peroxidase and tyrosinase) working in parallel and competing for the same substrate (catechol). The response of the biosensor to several hydroperoxides was investigated (LOD = 0.5 . 10(-4) M for hydrogen peroxide). It was experimentally found that the biosensor is able to respond also to aqueous solutions of ionic peroxides (LOD = 0.2 . 10(-4) M for potassium peroxidisulphate). The biosensor was applied to the determination of the hydrogen peroxide content of pharmaceutical products, i.e. aqueous disinfectant solutions (RSD% less than or equal to 0.5; recoveries by standard addition method between 96.0 and 98.5%). (C) 2003 Elsevier Science B.V. All rights reserved.