Electroanalysis of Caffeic Acid in Red Wine and Investigation of Thermodynamic Parameters Using an Ag Nanoparticles Modified Poly(Thiophene) Film Glassy Carbon Electrode

A silver nanoparticle decorated poly(thiophene) modified glassy carbon electrode (GCE) was prepared for determination of caffeic acid. The Ag/PTh/GCE surface was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. The modified electrode has shown higher electrocatalytic activity towards the oxidation of caffeic acid. The peak current of was found linear in the concentration range from 1.00×10−8 to 4.83×10−6 M with a detection limit of 5.3×10−9 M (S/N=3). The modified electrode was used for determination of CA concentration in red wine samples. The thermodynamic constants, entropy change (ΔS), enthalpy change (ΔH) and Gibbs free energy change (ΔG) were calculated as −166.34 J/(mol K), −154.24 kJ/mol and −104.75 kJ/mol at 25 °C, respectively.