Adsorption experiments with vitamin A concentrates

THE unsaponifiable matter of halibut-liver oil, after removal of the major part of the sterols, is a viscid orange-brown oil containing 60-70 % vitamin A, which on fractional distillation yields a pale yellow oil [Heilbron et al., 1932]. If the vitamin concentrate, whether purified by distillation or not, be dissolved in light petroleum and passed through a column packed with adsorbent (A1203 or Ca(OH)2) a red zone appears. Recovery of the adsorbed material by elution of the adsorbent with methyl alcohol shows that the colour is much more intense than that of the original concentrate. In view of the important biological relation between the red pigment carotene and vitamin A, this phenomenon has been studied in detail. At the same time, it was convenient to examine the reported separation of vitamin A into cx-and fl-forms [Karrer, Walker et at., 1933; As the main distinctions between these two forms and the other fractions obtained depend upon the spectroscopic -examination of the colours they produce with antimony trichloride, a brief r6sum6 of the earlier spectroscopic data on this reaction is necessary.