[Saturated fatty acids determination by GLC after TLC separation (author's transl)].

Abstract

The determination of fatty acid composition of oils and fats by conventional GLC on polar columns gives satisfactory results for most of the applications. Higher precision is, however, desirable when the content of minor components is of interest. A typical example is the quantitative determination of the percentage of peanut oil in a seed oil mixture, on the basis of the content of lignoceric acid (n-C21). Lignoceric acid, wich is containen in peanut oil in the amount of 1-2%, shows, on polar columns, a very long retention time and, owing to its low percentage, flat and non well measurable peaks. A method was therefore developed which allows an accurate determination of all saturated fatty acids, particulary of those with high molecular weight. The method is based on the separation of satured fatty acids by argentation TLC followed by GLC determination on non polar columns.