Gas-liquid chromatographic determination of vitamin D2 in fortified full-cream dried milk

Abstract

A gas-liquid chromatographic method is described for the determination of vitamin D₂(ergocalciferol) in full-cream dried milk that contained 10 µg of added vitamin per 100 g. The method involves extraction of the vitamin plus fat with a mixture of ethanol, sodium hexametaphosphate and a surfaceactive agent; saponification of the fat; and extraction of the unsaponifiable matter containing the vitamin with a mixture of light petroleum and diethyl ether. Cholesterol and other interfering substances are removed in a novel way by dry-column chromatography on two columns of aluminium oxide and the final determination of ergocalciferol is made by gas-liquid chromatography, using vitamin D₃(cholecalciferol) as an internal standard.

The method, which can be completed in 2 days, is also applicable to dried milk that has been fortified with cholecalciferol by using ergocalciferol as the internal standard. Results obtained by the proposed method are given for the ergocalciferol content of National Dried Milk and of some proprietary dried milk powders.