Determination of Vitamin D in Blood

Abstract

A method is described for the routine determination of vitamin D (D₂ and D₃) in whole blood, serum, or plasma of warm-blooded animals. One determination requires 20ml of blood; the standard deviation is 3 I. U. of vitamin D per ml; the method is reliable from 5 I. U. per ml upwards. The procedure comprises: saponification, benzene-washing isolation, elimination of cholesterol by digitonin, vitamin A and vitamin E by chromatography and absorptiometry after reaction with antimony trichloride. Plasma samples can be stored for years without change in vitamin D content.