The Dermination of Vitamin D3 in Chicken Egg Yolk by High Performance Liquid Chromatography
Cadwallader, Mark W.
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The chicken egg yolk, as deduced from its antirachitic activity, contains 1-2 ~g of cholecalciferol (vitamin D3) and this can be raised further by increasing the intake of vitamin D of the laying hen. This concentration in yolk is 5-10 times higher than that of total vitamin D plus its metabolites in blood plasma of normal chickens and 50-100 times higher than the concentration in any other tissue. Consequently, the chicken egg yolk is a potent source of vitamin D. Because several of the metabolites of vitamin D are biologically active, the molecular species of vitamin D which passes into the yolk cannot be determined just from measurement of antirachitic activity. Consequently, a quick, reliable, and sensitive method for determining the amount of the unchanged form of vitamin D, i.e. vitamin D3, in egg yolk would be extremely beneficial - both to those who are interested in the metabolism of vitamin D3 and to those who wish to study what factors influence the chicken to deposit vitamin D in the egg. To our knowledge such a method does not exist. With the recent advances in HPLC technology, and the increasing number of articles on the analysis of vitamin D in multivitamin products and of vitamin D metabolites in biological samples, good quantitation of vitamin D3 in egg yolk was considered to be feasible.