Dissolve about 0.5mg of Vitamin D2 into 5mL chloroform, add 0.3mL acetic anhydride and 0.1mL sulfuric acid, shake and mix vigorously. The mixture is initially produced bright red color, and then rapidly changes violet and finally blue to green.
Dissolve 10mg of vitamin D2 into 2mL of 90% ethanol, add 2mL solution of digitalis saponin and incubate for 18h. No precipitation or cloud should be observed.
Contains no Ergosterol.
References
Knudson, B., et al.: J. Biol. Chem., 124, 287 (1938), Huber, B., et al.: J. Biol. Chem., 149, 125 (1943), Crowfoot, D., et al.: Nature, 162, 608 (1948), Suda, et al.: Biochem. Biophys. Res. Commun., 35, 182 (1969)