Vitamin C sensor based on the cyclic reaction of L-ascorbic acid and dehydroascorbic acid using dithiothreithol

This chapter elaborates vitamin C sensor based on the cyclic reaction of l -ascorbic acid and dehydroascorbic acid using dithiothreithol. A cyclic reaction between the reduced and the oxidized forms of vitamin C takes place by combining the ascorbate oxidase reaction and the reduction of l -ascorbic acid to dehydroascorbic acid by dithiothreithol. The consumption of the dissolved oxygen by enzymatic reaction is not compensated by the chemical regeneration of L-ascorbic acid from dehydroascorbic acid. Consequently, the decrease of the reduction current of oxygen is amplified. Ascorbate oxidase catalysis the oxidation of l -ascorbic acid to dehydroascorbic acid (DAA) and can proceed the reaction in the opposite direction to that of the chemical reduction of l -ascorbic acid.