Abstract
The reaction product from vitamin B1 and cupric ion was found to give a red fluorescence and this relatively sensitive and selective reaction was applied to the detection of vitamin B1. A few milligrams of sample containing vitamin B1 were dissolved in about 1 ml of water and added one drop of 0.1% thymolphthalein solution. To the sample solution, 0.1 N sodium hydroxide solution was added drop by drop until the solution turned blue and two more drops were added. The thiolized solution was prepared by heating the sample solution in a water bath at 50-90° for 30 seconds. One drop of 0.5% cupric sulfate solution was put on a filter paper and after drying the paper, one drop of the thiolized solution was added on the spot. After 1-2 minutes, the red fluorescence was observed. The limit of identification was 3 μg (60μg/ml). This reaction is interfered by mercury, iron, sulfur-bearing compounds and vitamin B2.
