In addition to its natural occurrence in fruit and vegetables, ascorbic acid (Vitamin C) is used as an antioxidant in foods and drinks. Ascorbic acid is furthermore also to be found in numerous drugs.
Ascorbic acid and its salts and esters can be determined with titration or by using polarography, for which ascorbic acid is oxidized to form dehydroascorbic acid.
Bi-voltammetric or photometric equivalence point indication can be used for titrimetric determination. It must be taken into account here that only bi-voltammetric indication is independent of the inherent color of the sample. Polarography is the most selective of the methods described, as other reducing or oxidizing substances are not recorded.