抄録
When the vitamin D in liver oils containing much vitamin A is determined using Superfiltrol chromatography, a substance produced by the decomposition of vitamin A appears in the vitamin D fraction and it interferes with the determination of vitamin D. More non-vitamin D substance is present in the fraction prior to the vitamin D fraction. Experiments with the non-vitamin D substance obtained by passing a sufficient amount of the nonsaponifiable matter of vitamin A palmitate and of vitamin A acetate showed that the absorbances of the colored solutions by SbCl_3 reaction at 500 and 550mμ were preactically the same 120 seconds after adding the regent and that the colored solution of vitamin D by SbCl_3 reaction had the absorption maximum at 500mμ and the absorbance is 0 at 550mμ. Hence, the difference E_<500>-E_<550> after 120 seconds corresponds to E_<500> due to vitamin D, without any interference by non-vitamin D substance. Less than 4,000μg of vitamin A is without effect on the determination of vitamin D in one Superfiltrol chromatography. The use of ethylene dichloride containing acetyl chloride for the solvent of antimony trichloride in place of chloroform makes the reagent more stable and the reaction more intense. It is hardly influenced by the change in temperature. The condition appropriate to the determination was reported. Several liver oils obtained by molecular distillation, which are considered to produce much non-vitamin D interfering substance were used for assaying vitamin D. The values obtained by the above method were definitely lower than those calculated from E_<265>, assuming the absorbance entirely due to vitamin D. The experiment with the vitamin A fraction obtained by Superfiltrol chromatography showed that the value of E_<50>-E_<550> was negative. The absorption spectrum of the vitamin A fraction was different from that of vitamin A, showing the decomposition of the vitamin. The low recovery of the vitamin D added to the solution containing much vitamin A, therefore, is ascribed to the contamination of the vitamin A decomposition product.
