The determination of ascorbic acid in the presence of interfering substances, notably reductones

Abstract

Ascorbic acid is inert to indophenol or iodine in presence of 20% or 29% HC1, respectively, but on dilution with water the usual reaction occurs. Indophenol is reduced in presence of 20% HC1 by glucoreductone and other interfering substances. Ascorbic acid detn. in the presence of glucoreductone by a differential titration method is described. It is suggested that, in presence of moderately concentrated HC1, ascorbic acid exists as the unreducing keto-form.