Studies in vitamin A. 12. Whale-liver oil analysis: preparation of kitol esters

Whale-liver oil is valued for its vitamin A content, but this has so far been difficult to determine.Indeed, there has been no satisfactory alternative to the biological assay, which is itself of limited utility, if only because the fiducial limits of error (P = 0 95), using eighty rats, may often be no better than 70-140% of the estimated potency.Whale- liver oil is, moreover, a very variable material.The crude oil, obtained by processing livers at sea or in Antarctic stations, usually contains phospholipins, water, free fatty acids and vitamin A decom- position products, as well as other impurities.In addition there is kitol, a substance not known to occur in comparable quantity in any other fat.The