Determination of Vitamin A
Vitamin A assay is carried out by chemical method. This method is called Carr Price Reaction.
Vitamin A and the carotenoids produce an intense blue colour upon addition of a saturated solution of antimony trichloride in anhydrous and alcohol-free chloroform. This reaction is called Carr Price Reaction and used to determine Vitamin A. The absorption maxima is around 620 nm.
In another method, absorption of vitamin A dissolved in isopropyl alcohol is determined at wavelengths of 310, 325 and 334 nm. This method is suitable for the determination of pure vitamin A (or of the ester after their saponification), such as oily solutions as well as in tablets, coated tablets, capsules and other formulations.