Voltammetric detection of L-dopa and carbidopa on graphene modified glassy carbon interfaces

The present work reports on the use of graphene nanosheets, deposited on glassy carbon, as electrode materials, and their electrochemical characterization. The graphene nanosheets were obtained by chemical reduction of graphene oxide using hydrazine. The possibility of analyzing L-dopa and carbidopa, two important catecholamines found in pharmaceutical products, separately and simultaneously by differential pulse voltammetry utilizing graphene modified GC interfaces is investigated. Voltammetric peak currents showed a linear response for both catecholamines in the range of 1-16 μM. The detection limit was about two times lower for L-dopa than carbidopa being 0.8 μM and 1.8 μM, respectively with a current sensitivity of (2.15 ± 0.5) and (0.48 ± 0.3) μA μM(-1). Simultaneous detection of both catecholamines can be achieved on these electrodes. Equivalent amounts of L-dopa and carbidopa have no effect on the detection limit of L-dopa. In addition, the presence of L-dopa with concentrations 4 times higher than carbidopa has no influence on the voltammetric profile.