Reagentless Hydrogen Peroxide andL-Lactate Sensors Based on Carbon Paste Electrodes modified with different peroxidases and lactate oxidases

Abstract

Reagentless amperometric hydrogen peroxide and L-lactate electrodes based on bienzyme modified carbon pastes were tested and compared. The behaviour of 7 peroxidases and two lactate oxidases immobilized in carbon pastes were investigated amperometrically under flow injection conditions. By the combination of recombinant lactate oxidase from Aerococcus viridans (RLOD) and lactate oxidase from Pedicoccus sp. with (LOD) horseradish peroxidase, peroxidase form Arthromyces ramosus, microperoxidases MP-8 and MP-11 sensitive carbon paste electrodes were prepared to detect H2O2 and L-lactate. The selectivity with respect to several redox active substances and substrates of the peroxidases is slightly influenced by the selection of the heme containing peroxidase. The operational stability of both the hydrogen peroxide and the L-lactate sensors could be improved by electrochemical deposition of o-phenylenediamine onto bienzyme modified carbon paste electrodes. Despite microperoxidases have a considerably lower electro-catalytical efficiency per molecule, especially MP-8 can be used to modify carbon paste electrodes for sensitive H2O2 detection. Both MP-8 and MP-11 can be coimmobilized with LOD and RLOD to detect L-lactate.