Highly sensitive method for the quantification of trans-linolenic acid isomers in trilinolenin of edible oils using an ionic liquid capillary column.

BACKGROUND: The polarities of linolenic acid isomers are very similar, and only a few studies to date have attempted to separate α-linolenic acid (ALA) isomers completely. The aim of this study was to fill this gap by developing and validating an accurate method for the analysis of ALA isomers in trilinolenin at 200, 220 and 240 °C using a gas chromatograph-flame ionization detector equipped with an SLB-IL111 capillary column.

RESULTS: Results showed that eight ALA isomer standards were separated effectively using these optimized gas chromatographic conditions. The coefficient of determination was r2 > 0.9994 in the linear range of each ALA isomer. The obtained limits of detection and limits of quantification of the ALA isomers were 0.02-0.08 ppm and 0.05-0.22 ppm, respectively. A high degree of reproducibility and percent recoveries between 96.2% and 106.5%, with coefficients of variation ranging from 0.82% to 0.97%, were achieved.

CONCLUSION: The developed method has been successfully applied to the analysis of ALA isomers in heated pure trilinolenin as well as to trilinolenin in various edible oils, and the TALA isomerization pathways in heated trilinolenin were verified. © 2017 Society of Chemical Industry.