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

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Abstract
The acetone-soluble lipid from a sample of frozen blue-whale liver contained vit. A, 1%, with relatively little kitol. A similar extract from frozen sperm-whale liver was richer in vit. A and kitol (16 and approx. 20%, respectively, as esters). The fractionation of whale-liver oils was attempted in various ways. Free vit. A is extracted by means of 50% aqueous ethanol, and vit. A esters are separable from kitol esters by means of 80% aqueous ethanol. Chromatography of whale-liver oil on alumina (weakened by addition of 10% water) effects a clean separation of vit. A (esterified) from kitol (esterified). Kitol esters are difficult to saponify, and the free kitol tends to be decomposed unless precautions are taken. They contain, however, about half their weight of kitol. Kitol esters fed to rats are neither converted to vit. A nor stored in the liver. A chromatographic method for the detn. of vit. A in unsaponified whale-liver oils was described and tested. A fairly good separation of kitol from vit. A in whale-liver unsaponifiable fractions can be effected by extracting the vit. A with 50% aqueous ethanol, but the volume used limits the method to analytical work. Preliminary work on whale-liver phospholipins suggests that kitol is not present in the true acetone-insoluble lipid, but that it may occur in more than one type of combination. Vit. A and possibly kitol is present in fin-whale milk.

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