2] Separation of methyl esters of fatty acids by gas chromatography on capillary columns, including the separation of deuterated from nondeuterated fatty acids

Abstract

This chapter describes the separation of methyl esters of fatty acids by gas chromatography on capillary columns, including the separation of deuterated from nondeuterated fatty acids. Analyses of the composition of mixtures of fatty acid methyl esters by gas chromatography have been improved greatly by the introduction of capillary columns. The inner wall of such columns is coated with a thin film of stationary phase. They possess a much greater resolving power than columns packed with an inert granular material coated with the stationary phase. Capillary columns may not have the same response correction factor for all fatty acid methyl esters. The methyl esters of deuterated 14:0, 16:0, and 18:0 all separate readily from the corresponding nondeuterated species. Resolution of deuterated 16:1ω7 from the nondeuterated 16:0 presents some difficulties, because highly deuterated 16:1ω7 runs into the preceding, nondeuterated 16: 0 on moderately polar columns, such as silar-5 and butanediol succinate. It is found that at moderate deuterium contents deuterated 16:lω7 does not separate from 16: lω9, and deuterated 18:1ω9 is partially obscured by a small trans-18: lω9.