Electrocatalytic oxidation of ascorbate at glassy carbon electrodes modified with electrodeposited films derived from dihydroxybenzaldehyde isomers Original Research Article

The electrocatalytic oxidation of ascorbate at glassy carbon electrodes modified with electrodeposited films derived from dihydroxybenzaldehyde (DHB), in particular 2,3-DHB, 2,5-DHB and 3,4-DHB, has been examined. NADH can also be electrocatalytic oxidized at 2,3-DHB and 3,4-DHB modified electrodes. However, 2,5-DHB modified electrodes catalyzed preferentially ascorbate, while the oxidation of NADH is unaffected. In addition, we have carried out studies of the kinetics of the catalytic reaction, as well as permeability studies. The effect of increasing concentrations of ascorbate on the amperometric responses of 2,5-and 3,4-DHB modified electrodes was investigated. Catalytic currents are proportional to the concentration of ascorbate over the range of 0.2 to 3.0 mM. The detection limit was 0.16 and 0.05 mM for films derived from 2,5-DHB and 3,4-DHB, respectively. Selectivity was illustrated by the analysis of ascorbate at 2,5-DHB modified electrodes in the presence of NADH or 4-acetamidophenol.