EFFECT OF CYCLODEXTRINS ON THE ELECTROCHEMICAL-BEHAVIOR OF ASCORBIC-ACID ON GOLD ELECTRODES

The study of the inclusion complexes formed by ascorbic acid with beta -cyclodextrin at different pH is reported. Special attention is paid t o the electrochemical behaviour of ascorbic acid in the presence of th e macrocycle on gold electrodes. The modifications observed can be exp lained by the decrease in the diffusion coefficient of the complex and the presence of an additional chemical step, the dissociation of the complex prior to the electron transfer steps, The inclusion of ascorbi c acid in beta-cyclodextrin increases the stability of the guest molec ule to oxidising agents. Adsorption of beta-cyclodextrin on gold is al so detected, depending on the pH. No effect of ascorbic acid behaviour owing to the addition of alpha-cyclodextrin was observed.