A Vitamin A Concentrate of High Blue Value

Abstract

IN Science of March 16, p. 255, Prof. H. N. Holmes, in association with H. Cassidy, E. Hartzler and R. Manly, reports the preparation of a concentrate of vitamin A having a blue value of 144,000, that is, 14,400 times greater than the blue value of an average good medicinal cod liver oil. The starting material was the non-saponifiable fraction of halibut liver oil. This was chilled in methyl alcohol solution, to freeze out cholesterol, etc., filtered cold under nitrogen, transferred to pentane by addition of water, dried over anhydrous sodium sulphate and then, in pentane solution, cooled to about—70 ° C. with the aid of carbon dioxide snow mixed with alcohol and again filtered, with careful exclusion of oxygen. The cold pentane solution was next filtered through a Tswett column of very specially prepared carbon and washed completely through with pure pentane. The product obtained was a pale yellow viscous oil; different preparations showed blue values ranging from 105,000 to 144,000. The authors have not yet had time to analyse their concentrate or determine its molecular weight, spectral absorption bands, ex tinction coefficient or biological potency. Further reports of their work will be awaited with interest.