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 1–250 mg L−1 with a detection limit (evaluated as 3σ) 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 °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.