Determination of epinephrine in the presence of uric acid and folic acid using nanostructure-based electrochemical sensor

Fabrication and electrochemical characterization of a sensor for the determination of epinephrine (EP), uric acid (UA) and folic acid (FA) is described. The sensor  was prepared using carbon paste electrode (CPE) modified with 3,4-dihydroxybenzaldehyde-2,4-dinitrophenylhydrazone (DDP) and carbon nanotubes (CNTs), which makes the modified electrode highly sensitive for the electrochemical detection of these compounds. Cyclic voltammetry (CV) at various scan rates was used to probe the fabrication and characterization of the modified electrode. In order to characterize these new modified electrode, the electroanalytical response was evaluated for EP performing cyclic voltammetry, differential pulse voltammetry and chronoamperometry experiments. Under the optimum pH of 7.0, the oxidation of EP occurs at a potential about 215 mV less positive than that of the unmodified CPE. Differential pulse voltammetry (DPV) of EP at the modified electrode exhibited two linear dynamic ranges with a detection limit (3σ) of 70 nM. DPV was used for simultaneous determination of EP, UA and FA at the modified electrode, and quantification of EP in some real samples by the standard addition method.