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: i(pa1) = -4.25 × 10(-6) - 1.99c (mol L(-1)), R(1) = 0.9953; i(pa2) = -4.31 × 10(-5) - 0.315c (mol L(-1)), R(2) = 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.