Effect of cyclodextrrins on the electrochemical behaviour of ascorbic acid on platinum electrodes in acidic an neutral solutions

M.I.MANZANARES CUELLO, V.M.SOLIS AND R.H.DE ROSSI

JOURNAL OF ELECTROANALYTICAL CHEMISTRY

ELSEVIER

Lugar: Amsterdam; Año: 1997 vol. 430 p. 163 - 163

0022-0728

he effect of fl-CD and a-CD on the electrochemical behaviour of H2A and HA- on platinum is studied. The adsorption of/3-CD onthis electrode is demonstrated and proved to be dependent on the base electrolyte composition. The maximum adsorption coverage wasreached in l:hosphate solution at pH 6.95. The homogeneous H 2 A-/~-CD complex formation produced a decrease in the oxidation currentand a positive shift in the oxidation peak potential. These effects are predominant in acid solutions. In neutral solutions the oppositebehaviour is observed, i.e. an increase in the oxidation current at lower oxidation potentials. The presence of a parallel oxidation route forthe vitamin involving strongly adsorbed CO residues is considered, and evidence for a decrease in COad" in the presence of//-CD wasgiven by variations iu hydrogen adsorption charges. This fact, more important in neutral solutions, must be responsible for the catalyticeffect observed, a-CD was not adsorbed, neither did it modify the