Fractionation of oil triacylglycerols by reversed-phase high-performance liquid chromatography

Abstract

A study of the conditions of triacylglycerol fractionation by reversed-phase high-performance liquid chromatography (HPLC) with [ 14C]trioleoylglycerol showed that contamination by the adjacent peaks was very low (<0.6%); this was also proved by the high purity (>98%) of the re-chromatographed fractions. Triacylglycerols from peanut and cottonseed oils eluted according to increasing partition numbers, the latter generally being very close to the even numbers expected. The percentages of the fractions determined from peak areas (detection by differential refractometer) were close to those determined by the internal standard procedure. A study of the fatty acid composition of the isolated fractions did not lead to a precise determination of the triacylglycerol composition, except for the first fraction, composed mainly of trilinoleoylglycerol, and the second fraction, composed of palmitoyldilinoleoyl- and oleoyldilinoleoylglycerol. These two triacylglycerol fractions represented respectively 4.3 and 11.5% of peanut oil and 27.6 and 11.2% of cottonseed oil. Cottonseed oil triacylglycerols were first fractionated by argentation thin-layer chromatography according to their degree of unsaturation. When the fractions were re-fractionated by reversed-phase HPLC, according to their carbon number, very simple mixtures were isolated, which will serve as useful substrates for further analysis of the isomers of fatty acid positions in triacylglycerols.