Adsorption study of amino acids on a polycrystalline gold electrode

The adsorption of serine (Ser), tyrosine (Tyr) and histidine (His) on a gold electrode from 0.1 M LiClO4 aqueous solutions was investigated. The adsorbates studied are the natural amino acids that play an important role in various biological processes. The experimental data obtained from ac impedance measurements were analysed to determine the dependence of adsorption parameters, i.e. the standard Gibbs energy of adsorption (ΔG0) and parameter of interactions in the adsorbed layer on the electrode potential and pH of the solution. The Gibbs energy of adsorption was calculated by fitting Henryʹs and Frumkinʹs isotherms to the experimental data. It was found that adsorption of amino acids on the gold electrode decreases in the order, Tyr≥His>Ser. The parameters of adsorption of amino acids on the gold electrode were compared with the corresponding data for Hg electrode.