2020 Volume 69 Issue 4.5 Pages 179-185
For the sake of rapid and convenience analysis of trans fatty acid components, the authors developed a reaction field for thermally assisted hydrolysis and methylation-gas chromatography (THM-GC) capable of achieving highly efficient methylation of the components. At first, a trilinolenin standard sample was subjected to THM-GC in the presence of an organic alkali reagent, trimethylsulfonium hydroxide (TMSH) or trimethyl(trifluoro-m-tolyl)ammonium hydroxide (TMTFTH), to investigate the reaction behavior of fatty acid components. As a result, although cis-trans isomerization of the fatty acid components occurred during the THM reaction for both reagents, the use of TMTFTH proved to suppress the isomerization significantly. Then, the optimization of various reaction conditions in the presence of TMTFTH lead to a reduced cis-trans isomerization rate (0.12 %); the THM temperature and the ratio of the amount of the reagent to the sample were set at 180 °C and 40 times, respectively. Furthermore, THM-GC equipped with the developed reaction field was applied to quantitative analyses of trans fatty acid components in edible oils and fats, such as shortening and margarine. The obtained values coincided with the reference values, suggesting that the THM-GC method was able to be used for rapid and convenient determinations of trans fatty acid components.
