Amperometric glucose biosensor based on rhodium dioxide-modified carbon ink

An amperometric method for the determination of glucose using a screen printed carbon electrode is reported. The electrode material was bulk modified with rhodium dioxide and the enzyme glucose oxidase immobilized in a Nafion-film on the electrode surface and investigated for its ability to serve as a detector of glucose in flow injection analysis. The sensor exhibited a linear increase of the amperometric signal with the concentration of glucose in the range of 1250 mg L-1 with a detection limit (evaluated as 3 sigma) of 0.2 mg L-1 under optimized flow rate of 0.4 mL min(-1) in 0.1 M phosphate buffer (pH 7.5) carrier. At the potential applied (-0.2 V vs. Ag/AgCl), interferences from redox species present in the sample matrix were negligible. The biosensor reported here retained its activity for more than 40 injections or 4 months of storage at 6 degrees C. The RSD was determined as 1.8% for a glucose concentration of 25 mg L-1 (n = 5) with a typical response time of about 28 s.