2.2 Methods
2.2.1
Analysis of mixed tocopherols
Thin-layer chromatography (TLC) was employed to perform a qualitative
analysis of the composition of
mixed
tocopherols samples. A mixed tocopherols sample was loaded on a TLC
plate of silica gel for fractionation. A mixture of chloroform-ethyl
acetate (94:6, v/v) was chosen to be the developing solvent, and the
iodine vapor was used as the coloring reagent. These three tocopherols
and impurities were identified using α-, β-, γ-, δ-tocopherol and fatty
acid methyl ester standards. Quantitative analysis of mixed tocopherols
and their monomers were determined by high performance liquid
chromatography (HPLC) using the AOCS method specified in Chapter Ce
8-89.