Electrochemical evaluation and voltammetric determination of some phenolic acids on the boron-doped diamond electrode

A simple, sensitive, and rapid method of determining phenolic acids, i.e. caffeic, ferulic, syringic, and vanillic using boron-doped diamond electrode (BDDE) by differential pulse voltammetry (DPV) was described. To the best of our knowledge, this is the first presentation of an electrochemical method to determine these compounds on BDDE. Under the conditions presented, the mentioned analytes undergo irreversible oxidation controlled by diffusion. The measurement conditions and composition of the supporting electrolyte were developed and optimized. Optimal measurement parameters ensure the usage of 0.02 mol L (-1) ammonium citrate buffer pH 3.0 as a supporting electrolyte. The calibration graphs were linear with a correlation coefficient (r) >0.9959. The detection limits for the phenolic acids were within 0.01-0.03 mg L (-1). Repeatability in all experiments, expressed by RSD%, was better than 5 %. The influence of interfering metal ions, such as Bi3+, Cd2+, Cu2+, Pb2+ and Tl+, was studied. The proposed method was successfully verified by measuring recoveries of phenolic acids in the model wine solution. The standard addition method was also applied in the determination of syringic acid in homemade and commercially available products: walnuts, walnut tincture, fresh and dried thyme. Effective application of the described analytical approach with the usage of BDDE not only enables the electrochemical detection of these four phenolic acids but also helps to reduce operational costs.