The effect of additives on the free radical formation in aqueous solutions of ascorbic acid.

The relative rate constants for the decay of ascorbate free radical in aqueous solutions in the presence of heavy metal ions, hydrogen peroxide and sulphite were measured the ESR-spectroscopy. The oxidation of ascorbic acid showed a strong pH dependence, reaching a maximum rate at pH 9.6. It was shown that the ascorbic acid radical decay generally follows overall second order kinetics, being however first order in the presence of hydrogen peroxide. The protective effect of sulphur dioxide is proposed to have nutritional implications.