Thermal Decomposition of Vitamin A

Abstract

By the sterilization of drugs having vitamin A as their important component, such as cod liver oil, by the standard method set by J. P. of 2hrs. at 120°, loss of about 10% vitamin A unit must be expected. This loss becomes ca. 20% if heated for 5hrs. Experiments on the effect of air and light showed that no great difference existed by the presence or absence of air and in colorless or brown glass ampules at 120°. Sterilization at 150-160° showed a loss of 8.4% average for 15 minutes, 10.5% average for 30 minutes' heating. After 2 hours' heating, the effect of air inside the ampule seemed to be marked, those in brown glass ampules being much more advantageous. However, no such difference exists between one and two hour heating which may be due to the definite amount of air sealed in an ampule which makes oxidation proceed in a short time. In any event, the change occurs lineally, especially when no air is present. This proves that the thermal decomposition of vitamin A cannot be prevented by either removal of air and water or by prevention of light. It follows, therefore, that the decrease of vitamin A unit must be sought by means of using drugs without heating.