Vitamin D in foods includes vitamin D2 (calciferol), which is found in vegetable foods such as mushrooms, and vitamin D3 (cholecalciferol), which is found in animal foods such as powdered milk, meat, rice, egg, and fish. Other active ingredients include the metabolites 25-hydroxyvitamin D3, 1α, and 25-dihydroxyvitamin D3.
The vitamin D content in foods is small, typically several micrograms per 100 grams, which makes analysis difficult. Pretreatment requires removal of contaminants, hydrolysis to remove lipids, followed by solvent extraction. The extracts obtained as described in the Technical Note No33 are then concentrated and purified by preparative LC followed by a two stage HPLC analysis.
In this report, we have been able to purify samples after solvent extraction using size-exclusion chromatography (SEC) with an Inertsil Diol column, and then directly introducing the sample onto an analytical column using a heart-cut method. With this method samples can be analyzed in a single step without purification and concentration by LC separation.