Selective Determination of Epinephrine in the Presence of Ascorbic Acid Using a Glassy Carbon Electrode Modified with Graphene

A graphene-modified glassy carbon electrode was fabricated via a drop-casting method, and applied to the electrochemical detection of epinephrine. The capacity of the graphene-modified glassy carbon electrode for the selective detection of epinephrine was confirmed in a sufficient amount of ascorbic acid (2 mmol L-1) by cyclic voltammetry. The modified electrode showed an excellent electrocatalytical effect on the oxidation of epinephrine. A pair of well-defined redox waves were observed in voltammograms of epinephrine in a phosphate buffered solution (pH 4.0). The peak potentials of epinephrine remained unchanged, and the oxidation peak currents showed a linear relation versus the epinephrine concentration in the range of 3.85 x 10(-7) - 1.31 x 10(-5) mol L-1 and 1.31 x 10(-5) - 1.09 x 10(-4) mol L-1 with a correlation coefficient as follows: i(pa1) = 4.25 x 10(-6) - 1.99c (mol L-1), R-1 = 0.9953; i(pa2) = 4.31 x 10(-5) - 0.315c (mol L-1), R-2 = 0.9988. Detection limit is estimated to be 8.9 x 10(-8) mol L-1. Graphene-modified glassy carbon electrode was applied to epinephrine sample analysis, and the results were in good agreement with the standard values.