ANODIC OXIDATION OF DIFFERENT IONIC FORMS OF SERINE ON THE Pt(Pt)-ELECTRODE

Abstract

Abstract. The task of the work was to establish the infl uence of the charge state serine determined by the pH value of the medium on kinetic regularities and quantitative characteristics of the process of its anodic oxidation on a platinized platinum electrode. The study was performed by the methods of voltammetry, coulometry, rotating disk electrode and IR-spectroscopy with Fourier transform. As base solutions used 0.1 M NaOH, 0.05 M solution of H2SO4 and acetate buffer with a concentration of salt and acid, 0.5 M and 0.05 M, respectively. The electrode potentials region of the electrochemical conversion of the amino acid was determined. The current of oxidation of anion serine is signifi cantly higher, than cation or zwitterionic form. This can be explained by difference in adsorption activity of anion serine on the surface of platinized platinum. The concentration of the various ionic forms of serine in solution before and after electrooxidation was determined photometrically. It is shown that serine electrooxidation occurs with the participation of 2 electrons in acidic and alkaline environments, whereas zwitterion oxidation is accompanied by 4 electrons transfer. It is established that electrooxidation of serine is carried out from an adsorbed state regardless of solution pH. The possible kinetic scheme of the electrooxidation process is proposed. The rate of electrooxidation of the cation or anion of serine is determined by the stage of transfer of the fi rst electron. The rate of electrooxidation of zwitterion of serine is determined by the stage of transfer of the second electron. Electrooxidation of all ionic forms of serine is kinetically irreversible.

Keywords

• serine
• amino acid
• electrooxidation
• voltammetry.