Oleuropeine determination in some folk medicinal plants by squarewave cathodic stripping voltammetry

In this study, electrochemical properties of Oleuropeine were investigated by cyclic voltammetry and its determination were performed by square wave anodic stripping voltammetry in the leaves of Olea europaea, Fraxinus ornus, Ligustrum vulgare and Fraxinus excelsior in the use of diabetic folk medicine. Transferred electron number of oleuropeine was found as 1 during reduction, diffusion coefficient was found as 4.9 x 10-8 cm2/s and pKa value was 7.4. In addition, pH, deposition time, puls amplitude, frequency and deposition potential were optimized as analysis parameters. In this method, detection limit of oleuropeine and limit of quantification of oleuropeine were found as 3.29 x 10-6 M and 9.87 x 10-6 M, respectively. Oleuropeine concentration was found as 0,46%, 0,4%, 0,25% and 0,05% in the leaves of Olea europaea, Fraxinus ornus, Ligustrum vulgare, Fraxinus excelsior respectively. Oleuropeine concentration was also determined by HPLC in order to comparison of the methods and similar results were obtained.