Abstract
Methods for the gas-liquid chromatographic (GLC) determination of vitamin D in multivitamin preparations as described in the previous reports^<1), 2)> were applied to various kinds of commercial samples. The first method^<1)> including separation of the unsaponifiable matters, thin-layer chromatography (TLC) and GLC was applied to usual samples, while the second method^<2)> including separation of the unsaponifiable matters, phosphate-treated alumina column chromatography^<5)>, TLC and GLC was applied to the samples containing excess amounts of vitamin E (more than 2,500 of the weight ratio of DL-α-tocopheryl acetate to vitamin D). When vitamin D contents in 6 kinds of commercial samples were repeatedly estimated by either the proposed first or second method, good reproducibility was obtained in all cases. The methods were also applied to 3 kinds of commercial samples stored for about 1 year at either room temperature or 40℃. Although the samples contained comparatively large amounts of decomposed products of vitamin D, A and others formed during storage, the pyrovitamin D peaks were not disturbed by decomposed products on the gas chromatograms. From these results, the proposed methods were confirmed to be suitable routine for the determination of vitamin D in commercial multivitamin preparations.
