[Analysis of fatty acid composition in cottonseed by gas chromatography with on-line pyrolytic methylation]

A method of on-line pyrolytic methylation-gas chromatography was developed for the analysis of fatty acid composition in cottonseed. Fatty acids in cottonseeds were converted to their corresponding fatty acid methyl esters in the presence of trimethylsulfonium hydroxide at 300℃. The major fatty acids were linoleic acid (C18:2), oleic acid (C18:1), palmitic acid (C16:0), stearic acid (C18:0), myristic acid (C14:0), palmitoleic acid (C16:1), arachidic acid (C20:0) and docosanoic acid (C22:0). The unsaturated fatty acid content varied from 66.30% to 72.54%, and linoleic acid content varied from 43.20% to 53.61%. The RSDs of the peak areas of the fatty acids were less than 10% (n=5). The fatty acid compositions in the cottonseed samples, obtained from different growing places and different edible oil samples were compared by statistical analysis. The results showed that fatty acid compositions in cottonseed samples from different regions were similar. The fatty acid composition in cottonseed samples was closest to that of corn oil, and the similarity varied from 0.960 to 0.992. The method is simple, rapid, accurate, and is suitable for the analysis of fatty acid composition in cottonseed.