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

Abstract

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), R₁ = 0.9953; i_pa2 = −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.