Spectrographic studies on the antimony trichloride reaction for vitamin A

Abstract

Attempts were made to remove the inhibition of the 606 m[mu] band of the SbCl3 reaction shown by cod liver oils, especially when very fresh. An appreciable increase in absorption, but no definite max., was obtained by oxidation with air or by addition of halogen oxidants before or after the reagent. Addition to the reagent of Cl2, SbCl5 or Br2 resulted in higher absorption maxima than by any other method, independent of the degree of oxidation of the oil. The ratio between the 606 and 572 m[mu] band became nearly constant, approaching that of pure vit. A. The inhibition was probably completely or almost completely removed by oxidizing reagent. Br2 is the best oxidizing agent, and 0.1 g/1 is a suitable conc. With this reagent the relation between B.V. and E606 m[mu] followed the equation: B.V.= E0.75.