Abstract
1. Addition tests of synthetic ascorbic acid to raw materials were performed according to the methods of Kadin, Mizutani and Miki. The former two methods showed extremely low recoveries, while the latter was not quite satisfactory for food analysis.
2. The cause of the fluctuations of the recovery of added ascorbic acid was studied using the norit-hydrazine method and by paper chromatography. The results obtained were corrected by the recovery curve plotted against each drying time, but the significant errors could not be avoided.
3. The effect of drying with air from a drier the spotted sample on the paper and of development on the oxidation of the vitamin was tested. No effect of hot or cold air was recognized for a short time, but the recovery was considerably low when a great amount of the solution was spotted.
4. The use of a vaccum high frequency induction heater for drying was proved to give practically accurate results.
5. The effect of various solvent systems on the prevention of the oxidation of the vitamin were tested and the reasonable results could be obtained by paper partition chromatography using a vacuum high frequency induction heater for drying and a mobile phase containing 10% metaphosphoric acid for development.
