抄録
It is necessary to correct the iodine content with the standard solution of vitamin C before the oxidation-reduction titration using gargle iodine is performed. Quantitative analyses using the gargle solution made clear that the vitamin C content in commercial beverages are not inconsistent with the values on the label of the bottle, because the vitamin C is gradually decomposed by oxygen gas in the air. Although the new titration method is very easy and simple, it will add a quantitative consideration to the chemical experiments by high-school students. Although the method is also applicable for measuring the vitamin C content of madarin oranges on the market, it is noteworthy that the observed values are widely spread.
