Simultaneous Determination of Epinephrine and Uric Acid at Poly (Guanine) Modified Glassy Carbon Electrode

An electrochemical sensor based on poly (guanine) modified glassy carbon electrode (PGA/GCE) was fabricated by electropolymerization of guanine on a bare GCE surface. Scanning electron microscope (SEM) was employed to characterized the electrode surface. This modified electrode exhibited a good electrocatalytic property towards the oxidation of epinephrine (EP) and uric acid (UC) in 0.1 M phosphate buffer solution (PBS) (pH 4.0) due to the enhanced peak currents and well-defined peak separations. Under optimum reaction conditions, the oxidation peak currents of EP and UA were proportional to their concentrations in the ranges of 1.0 × 10−5 to 1.0 × 10−3 M for both two compounds, and the detection limits were 1.8 × 10−6 and 5.0 × 10−7 M, respectively. Finally, this method was efficiently used for the determination of EP in EP injections.