Gas-liquid chromatographic determination of vitamin D in multivitamin preparation

Gas-liquid chromatographic (GLC) determination of vitamin D in multivitamin preparations was investigated and a simple routine method was established. The unsaponifiable matters of a sample was applied to a thin-layer chromatography (TLC) plate using Kieselgel GF254 as an adsorbent and a mixture of n-hexane-ethyl acetate (4:1) as a developing solvent. The scraped zones corresponding to vitamin D and previtamin D were extracted and determined by GLC using 1.5% OV-17 packed on Shimalite W (80-100 mesh) as a stationary phase. When the proposed method was applied to model preparations made by mixing vitamin D, A and E, it was confirmed that the determination of vitamin D was possible when the ratios of vitamin A and E (DL-alpha-tocopheryl acetate) to vitamin D were within 104 (I.U. ratio) and 2,500 (weight ratio), respectively. Since the ratios of most of commercial multivitamin preparations on sale in Japan are within the limitations and the results on multivitamin preparations were also satisfactory, the proposed method was confirmed to be suitable simple routine.