Voltammetric determination of α-lipoic acid using poly(Vanillin) modified platinum electrode

Abstract

In the present study electrochemical detection of alpha-lipoic acid (alpha-LA) was carried out with a poly(Vanillin) modified platinum electrode p(VA)/PtE in Brinton Robinson buffer (BR) solution. The platinum electrode surface's was modified with cyclic voltammetry method. The prepared Pt electrode was characterized by cyclic voltammetry in ferrocyanide and scanning electron microscopy (SEM) images. The number of cycles and scan rate effects were studied using square wave voltammetry (SWV) in BR buffer containing 1 mM alpha-LA. The electrochemical oxidation of alpha-lipoic acid on the modified Pt electrode is influenced by the pH and it is an irreversible reaction in which one electron and one proton are transferred. Electrolyte type and pH effect were studied. The anodic peak current shows a linear increase with alpha-LA concentrations ranging from 0.03 mM to 2.00 mM at pH 5, the detection limit being of 0.025 mM. The alpha-lipoic acid quantification in synthetic urine samples was made by SWV with the modified Pt electrode.