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 × 10−7 - 1.31 × 10−5 mol L−1 and 1.31 × 10−5 - 1.09 × 10−4 mol L−1 with a correlation coefficient as follows: ipa1 = −4.25 × 10−6 - 1.99c (mol L−1), R1 = 0.9953; ipa2 = −4.31 × 10−5 - 0.315c (mol L−1), R2 = 0.9988. Detection limit is estimated to be 8.9 × 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.