Screening of seed lipids for γ‐linolenic acid: Capillary gas‐liquid chromatographic separation of 18:3 fatty acids with Δ5 and Δ6 double bonds

γ‐Linolenic acid (6c,9c,12c‐18:3) has recently become important for dietary and pharmaceutical applications. The reported occurrence of γ‐linolenic acid in seed oils from plant families known to produce fatty acids, including 18:3 acids, with Δ5‐ cis and Δ5‐ trans double bonds makes it necessary to distinguish between 5c,9c,12c‐, 5t,9c,12c‐ and 6c,9c,12c‐octadecatrienoic acids by gas chromatography (GC) alone in routine screening operations. The separation of these acids using two different capillary GC systems has been investigated. The successful separation of octadecatrienoic acids with 5c, 5t and 6c double bonds is shown by way of gas chromatograms of the fatty acid methyl esters obtained from the seed oils of four different species of the family Ranunculaceae and of Xeranthemum and Pinus .