title: Electrocatalytic oxidation of ascorbate by heme-FeIII/heme-FeII redox couple of the HRP and its effect on the electrochemical behaviour of an L-lactate biosensor.
abstract: The measurements of L-lactate using the carbon paste electrode modified with lactate oxidase (LOD), horseradish peroxidase (HRP) and ferrocene (FcH) operating at low working potential in flow injection mode showed that the intensity as well as the shape of peaks were dependent on the concentration of the reducing species present in samples (e.g. ascorbate) even at low operating potentials (-200 to 0 mV vs. Ag/AgCl). The mechanism of the electrochemical contribution of ascorbate to the L-lactate response was examined by using cyclic voltammetry, hydrodynamic voltammetry and FIA results. Comparative studies showed that HRP was catalytically active for the oxidation of ascorbate leading to a decrease in the cathodic electrochemical signal of L-lactate. The results of our investigation postulated that the direct electron transfer from the HRP-Fe(III)/HRP-Fe(II) redox couple to the electrode surface was involved in the electrocatalytic oxidation of ascorbate at the electrode surface.
authors.affiliation: Groupe Méthodologie Electrochimique-UMR-CNRS 6006, FCUN-CNRS 2465, Faculté des Sciences et des Techniques 2, rue de la Houssinière, B.P. 92208 44322 Nantes Cedex 03, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Ledru
authors.forename: Mohammed
authors.initials: M
authors.lastname: Boujtita
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D004563:Electrochemistry; D004566:Electrodes; D004579:Electron Transport; D006418:Heme / Q000737:chemistry* / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000737:chemistry* / Q000378:metabolism; D007773:Lactates / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D011199:Potentiometry
chemical_list: D007773:Lactates; D006418:Heme; D002244:Carbon; D006735:Horseradish Peroxidase; D001205:Ascorbic Acid