Abstract
Summary
Antimony trichloride may be used effectively as a reagent to differentiate vitamin A from carotene. In chloroform solution antimony trichloride and carotene interact with the formation of a blue color, which persists after heating on the water-bath at 60° C. Under similar conditions antimony trichloride and vitamin A-bearing oils develop at room temperature a blue color. On the application of heat the blue color changes to rose, violet-red or wine-red, depending upon the concentration of the vitamin.
Pyrocatechin, which Rosenthal and Erdelyi employed along with the antimony trichloride reagent to differentiate vitamin A from carotene, is not only needless, but it actually inhibits the formation of the blue color with carotene and of the blue color with oils rich in vitamin A at room temperature and of the rose or violet-red after heating. Aged solutions of pyrocatechol exert even greater inhibitory powers than fresh solutions.
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