Abstract
A routine method for the determination of vitamin D in commercial fortified dried milks was established by using high-performance liquid chromatography (HPLC). The method includes extraction of the fat, alkalisaponification, isolation of the unsaponifiable matters, digitonin-Celite and Florex-XXS column chromatography, thin-layer chromatography (TLC) and HPLC. Since co-chromatography performed by mixing the sample solution with authentic vitamin D_2 gave mono peak, vitamin D in the fortified samples was confirmed to be vitamin D_2. Although the samples contained comparatively large amounts of sterols, vitamin A, E, their decomposed products and other interfering materials, their influences could be eliminated by the procedure. When the proposed method was applied to 5 kinds of commercial samples, the assayed values of vitamin D_2 were between the range of 98.0%〜126.3% to each indicated value. From these results, the proposed method were confirmed to be useful for the determination of vitamin D in commercial fortified dried milks.
