STUDIES ON VITAMIN D IN AQUATIC ANIMALS-I

In a method for determining vitamin D in animal oils, proposed by Ewing et all). and modified by Numata2), 3), the oil is saponified, sterols removed by precipitation in cooled methanol and vitamin A removed by chromatography with Superfiltrol (SPF). Vitamin D is then determined spectrophotometrically after adding SbCl3 reagent. The absorption values at 500 mμ are compared to samples of vitamin D put thorough same process. In the present work, adsorption on weakened alumina (10% water in alumina) was intro-duced as a further purification process after chromatography and before addition of SbCl3. The absorption values of unknown samples and reference vitamin D samles were determined at 490mμ, 500mμ and 508mμ and the following formula was obtained which eliminates the need for vitamin D reference material. E5oomμ (corrected) =E5oomμ (observed 60 seconds after addition of SbCl3) × [function of] [function of]=7-3.ll × E490mμ (observed)/E500mμ (observed) - 3.89 × E500mμ (observed)/E500mμ (observed) The method under report was found applicable to samples containing vitamin D at a level as low as 1/550 of the vitamin A content (Table 4).