Analytical techniques for hydroxy acids in fats and oils

Analysis of lipids containing hydroxy fatty acids

Lipids containing hydroxy fatty acids or hydroxyacyl moieties are acetylated with [1-14C]acetic anhydride or [3H]acetic anhydride, and the content of hydroxy fatty acids or hydroxyacyl moieties is estimated from the specific radioactivity of the acetylated products with respect to that of radioactive standards, such as radioacetylated ricinoleic acid or triricinoleoylglycerol. Mixtures of triacylglycerols containing one, two and three hydroxyl groups per molecule are derivatized in a similar manner, and the resulting acetates are fractionated by thin layer chromatography according to the number of acetate groups per molecule. The relative proportion of each type of triacylglycerols in the mixture is estimated from the distribution of radioactivity in the various fractions. Applications of these techniques are demonstrated by the analysis of several seed lipids.