Electrochemical characterization of poly(fuchsine acid) modified glassy carbon electrode and its application for simultaneous determination of ascorbic acid, epinephrine and uric acid

Electropolymerization of fuchsine acid (FA) was studied by cyclic voltammetry on the surface of a glassy carbon (GC) electrode in different electrolyte media. Then, a novel Au-nanoparticle poly-fuchsine acid film modified glassy carbon electrode (poly(FA)/AuNP/GCE) was constructed for the simultaneous determination of ascorbic acid (AA), epinephrine (EP) and uric acid (UA). The resulting poly(FA)/AuNP modified glassy carbon electrode was characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The poly(FA) film had an efficient electrocatalytic activity for the oxidation of AA, UA and EP, and decreased the charge transfer resistance of electrode. In addition, the poly(FA)/AuNP/GCE separate oxidation peak potential of AA-EP by 150 mV and EP-UA by 180 mV, while bare GCE fails to resolve them. Differential pulse voltammetry results exhibited linear dynamic range of 5.0-1120.0 μmol L− 1 for AA, 0.5-792.7 μmol L− 1 for EP and 2.85-650.2 μmol L− 1 for UA with detection limits (S/N = 3) of 0.009 μmol L− 1, 0.01 μmol L− 1, and 0.03 μmol L− 1 for AA, EP, and UA, respectively. The diffusion coefficient for the oxidation reaction of EP on AuNP/poly(FA) film coated GC electrode was calculated as 2.6(± 0.10) × 10− 5 cm2 s− 1. The present method was applied to the determination of EP in pharmaceutical samples, AA in commercially available vitamin C tablet, and UA in urine samples.