Development of an interference-minimized amperometric-FIA glucose biosensor at a pyrocatechol violet/glucose dehydrogenase-modified graphite pencil electrode

A modified disposable electrode formed by immobilization of glucose dehydrogenase (DHG) onto pyrocatechol violet (Pcv)-modified graphite pencil electrode (GPE) was proposed for the flow injection (FI) amperometric glucose biosensor. Cyclic voltammetric experiments show that Pcv illustrates a good electrocatalytic effect towards the oxidation of enzymatically produced NADH. Although electrocatalytic oxidation of enzymatically generated NADH at the DHG/Poly-Pcv/GPE was successfully performed at + 250 mV in FIA system, some molecules such as ascorbic acid (AA), dopamine (DA) and uric acid (UA) give a significant positive interference due to their oxidation at this working potential. To overcome these interferences, an injector filled with a pre-oxidant, sodium bismuthate (NaBiO 3 ), was used in the FI amperometric glucose biosensor at the DHG/Poly-Pcv/GPE. Results showed that the interferences of these molecules were significantly minimized, because they were oxidized by NaBiO 3 in the injector before reaching the electrode surface in the flow cell. The constructed biosensor showed that a linear calibration curve was obtained in the range between 5.0 µM and 500 µM glucose with a detection limit of 1.2 µM. This proposed glucose biosensor including elimination of interferences of some oxidizable species was successfully applied to the real and artificial samples.