The analysis of mixtures of animal and vegetable fats : V. Separation of sterol acetates by thin-layer chromatography in reversed-phase systems and on silica gel G-silver nitrate layers☆

Abstract The analysis of sterols by means of thin-layer chromatography (TLC) is investigated. Previous experiments of the authors on the reversed-phase system undecane/acetic acid—acetonitrile (1:3) are amplified. For identification purposes the sterols are characterised by their so-called carbon numbers. By adding bromine to the mobile phase several critical pairs of sterols were resolved. The properties of this “bromine system” are discussed. On silica gel G—silver nitrate layers the sterols or their acetates are separated according to their degree of unsaturation. The procedures for this AgNO 3 TLC, which enable a clear separation of many sterols, are described in detail. The above chromatographic analyses can be applied to the identification of unknown sterols isolated from natural sources, e.g. coconut fat and Asterina pectinifera .