Determination of α-tocopherol and ergocalciferol by thin-layer chromatography

Abstract

A procedure was developed for determining α-tocopherol (vitamin E) and ergocalciferol (vitamin D2) in oils. The procedure involved the alkaline hydrolysis of an oil according to GOST (State Standard) 30417 followed by the independent recovery of vitamins by extraction with organic solvents. The extracts were separated on Sorbfil plates with the stationary phase of silica gel with a particle size of 5–12 μm by eluting vitamin E with an octane-diethyl ether mixture (7: 1) and vitamin D2 with a tetrachloromethane-diethyl ether mixture (4: 1). The zones of α-tocopherol and ergocalciferol were developed with conc. HNO3 and conc. H2SO4, respectively. The plate scanning and image processing were performed with a Sorbfil Videodensitometer software. The calibration plots were linear in the range of 2.5–15 and 15–50 mg/mL for α-tocopherol and 0.08–0.13 mg/mL for ergocalciferol. The procedure was used to determine vitamins in bur marigold oily extract and grape seed oil.