Minimization of Interferences in Flow Injection Amperometric Glucose Biosensor Based on Oxidation of Enzymatically-produced H2O2

One of the major problems in amperometric biosensors based on detection of H2O2 produced by enzymatic reaction between oxidase enzymes and substrate is the interference of redox active compounds such as ascorbic acid (AA), dopamine (DA) and uric acid (UA). To minimize these interferences, sodium bismuthate was used for the first time as an insoluble pre-oxidant in the flow injection (FI) amperometric glucose biosensor at a Glucose oxidase (GOx) immobilized Pt/Pd bimetallic modified pre-anodized pencil graphite electrode (p.PGE). In this context, these interfering compounds were injected into a flow injection analysis (FIA) system using an injector which was filled with NaBiO3. Thus, these interferents were converted into their redox inactive oxidized forms before reaching the electrode in the flow cell. While glucose was not influenced by the pre-oxidant in the injector, the huge oxidation peak currents of the interferents decreased significantly in the biosensor. FI amperometric current time curves showed that the AA, DA and UA were minimized by 96 %, 86 %, and 98 % respectively, in the presence of an equivalent concentration of interferences in a 1.0 mM glucose solution. The proposed FI amperometric glucose biosensor exhibits a wide linear range (0.01-10 mM, R-2=0.9994) with a detection limit of 2.4x10(-3) mM. Glucose levels in the artificial serum and two real samples were successfully determined using the fabricated FI amperometric biosensor.