A Chromatographic Method for the Estimation of Oleic and Linoleic Acids in the Presence of Straight-chain Saturated Fatty Acids

Abstract

Two communications have recently appeared in Nature on the chromatographic separation of naturally occurring fatty acids or their esters. Nijkamp¹ uses a silica gel column for the separation of C₁₀ to C₂₀ saturated acids. Cropper and Heywood² have evolved a rapid vapour-phase technique for the separation of the methyl esters of saturated acids which they state will be investigated for use in the separation of linolenic, linoleic and oleic acids. In the course of investigations on the biochemical changes occurring during ripening of oil palm fruits, and during germination of oil palm and water melon seeds, we have developed a chromatographic method for estimating oleic and linoleic acids in the presence of saturated straight-chain acids from C₈ to C₂₀. This is based on the reversed–phase chromatographic procedure of Howard and Martin³, later modified by Popjàk and Tietz⁴ for the analysis of saturated acids from C₁₀ to C₁₈, and by Silk and Hahn⁵ for similar acids from C₁₆ to C₂₄. Acetone–water mixtures varying from 45 per cent acetone (C₁₀) to 90 per cent acetone (C₂₄) have been recommended as eluting agents, the acids being estimated by titration with 0.01 N alcoholic potassium hydroxide to a bromthymol blue end-point.