Standardisation of the antiscorbutic potency of ascorbic acid

Abstract

By the tooth protection method with large numbers of guinea-pigs receiving ascorbic acid or orange juice at various identical levels 2 mgm. of ascorbic acid were found equivalent to 3 cc. of orange juice. The value agrees with the amount of ascorbic acid actually present in average specimens of orange juice or in "good" lemon juice, as determined by titration (0.6-0.7 mg. per cc.). Ascorbic acid therefore has a potency of 15 International Units per mgm. Possible reasons for the lack of agreement with Key and Morgan''s figure of 7.4 units are discussed. Different specimens of lemon juice vary in potency and had ascorbic acid contents varying from 0.19 to 0.69 mgm. per cc, average 0.47 with an average deviation of [plus or minus]0.11. The earlier conclusion is confirmed, that lemon juice is an unsatisfactory standard and should be replaced by ascorbic acid.