Application of Thin-Layer Chromatography to the Quantitative Estimation of Antioxidants: BHA, BHT, PG, and NDGA

A procedure is described for the quantitative estimation of BHA, BHT, PG, and NDGA in lard. The antioxidants are extracted from n-hexane solutions of the fat with 80% ethyl alcohol and acetonitrile, separated by two-dimensional thin-layer chromatography using benzene and acetonitrile, and estimated quantitatively by colorimetric methods after extraction of the spots. A special flask for concentration and a suction tube assembly for spot pickup are described. Recoveries of the antioxidants from lard were in the following ranges: BHA, 98-101%; BHT, 96-101%; PG, 90-101%; NDGA, 82-98%. The advantages of the method over others in use are that (I) all four antioxidants can be estimated in one aliquot of fat, (2) PG and NDGA can be estimated when present together in mixtures, and (3) the isomers of BHA can be effectively separated.