Simultaneous determination of ellagic and gallic acid in Punica granatum, Myrtus communis and Itriphal formulation by an electrochemical sensor based on a carbon paste electrode modified with multi-walled carbon nanotubes

Abstract

An electrochemical method for the determination of ellagic acid (EA) and gallic acid (GA) was successfully applied to extracts of Punica granatum, Myrtus communis, and to Itriphal, a herbal formulation. The voltammetric determination of EA and GA was conducted with a novel sensor based on a modified carbon paste electrode with multi-walled carbon nanotubes. The electrochemical behavior of EA and GA at the modified sensor was characterized by cyclic voltammetry, chronocoulometry, linear sweep voltammetry, differential pulse voltammetry and rotating disk electrode voltammetry. Electrochemical parameters such as the diffusion coefficient (D), electron transfer coefficient (α), electron transfer rate constant (k) and ionic exchange current density (I_o) were determined for EA and GA oxidation. The detection limit of GA was 0.2 μM and for EA was 0.21 nM over the 180 s accumulation time of the open circuit potential, respectively.