A Nitrogen Doped Graphene Oxide-Immobilized Glassy Carbon Electrode for the Simultaneous Detection of Dopamine, Uric Acid and Ascorbic Acid

Nitrogen-doped graphene oxide (NGO) was prepared by rapid thermal pyrolysis of polyvinylpyrrolidone (PVP) in a graphite oxide mixture. The NGO was immobilized on a glassy carbon electrode (GCE) by dispersion of NGO in a Nafion solution, and coating of the mixture on the GCE for drying. This modified electrode, GCE/NGO-Nafion, was applied to simultaneously determine small biomolecules of dopamine (DA), uric acid (UA) and ascorbic acid (AA). Due to its unique surface structure and properties originating from NGO showed highly electrocatalytic activity toward the oxidation of DA, UA and AA. When NGO was immobilized onto the GCE, the sensitivity of DA was found to be 5.621 µA µM^-1cm^-2 in the concentration range of 0.4-4.0 µM and 2.047 µA µM^-1cm^-2 in the concentration range of 4.0-20 µM. Similarly, in the UA concentration range of 6.0-48 µM and 48-330 µM, the sensitivity of UA was found to be 0.433 and 0.119 µA µM^-1cm^-2, respectively. Similarly, in the AA concentration range of 150-400 µM and 400-2000 µM, the sensitivity of AA was found to be 0.038 and 0.009 µA µM^-1cm^-2, respectively. These results demonstrate that NGO is a promising candidate of advanced electrode material in electrochemical sensing and other electrocatalytic applications.

Acknowledgement

The authors gratefully acknowledge the National Science Council of Taiwan for the financial support (102-2221-E-006-223).