Electrocatalytic oxidation of H2O2 at an oxycobalt film modified glassy carbon electrode for fermentation monitoring

Glassy carbon electrodes coated with thin oxymetallic films of Co(II), Fe(II), Ni(II), Pb(II), Ce(III), Cr(III), Tl(I) and Mn(II) were investigated for the presence of electrocatalytic effect towards H2O2 oxidation. Of these, Co(II), Ni(II), Pb(II), Ce(III) and Mn(II) were found to exhibit such an effect in alkaline medium, with Co(II) showing the strongest effect. Further studies with the Co(II) modified glassy carbon electrode as amperometric detector, in the wall-jet configuration, for flow injection analysis (FIA) demonstrated that only a low operating potential of +0.175 V (vs. Ag/AgCl, saturated KCl) was needed for good sensitivity. For flow injection analysis, linearity of H2O2 calibration was found from 5.00x10(-8) to 0.10 M and the detection limit was 5.0x10(-9) M (S/N=3). The electrode showed good stability (at least two weeks operation) and can be usefully applied to glucose determination in the fermentation broths without interferences. (C) 1997 Elsevier Science B.V.