Gas chromatography/mass spectrometry with chemometric methods for the determination of fatty acid profiles in herbal oils

The conventional method for analyzing fatty acid is gas chromatography (GC) with polar capillary columns. However, owing to the high cost and the sensitivity of these columns to the presence of water and oxygen, these columns are not the best choice for separation. Also, analyzing long-chain acids (>C28) with polar columns is impossible. On the other hand, complete separation with nonpolar columns is not possible for some saturated, unsaturated and long-chain fatty acids. Therefore, in this study, with the help of chemometric methods, a method was developed using GC/mass spectrometry (MS) with a nonpolar column to resolve the peaks to completely separate and accurately identify and quantify fatty acids. Using this method, the fatty acid profiles of the seed oils of Sesamum indicum L, Nigella sativa, Pimpinella anisum, Linum asitatissimum L, Silybum marianum and Amygdalus communis L. var. Amara and var. Dulcis were identified. Through applying the multivariate curve resolution method after GC/MS, the C-18 fatty acids such as alpha-linolenic, linoleic, oleic and stearic acids were separated and quantified. Also, the total percentages of identified fatty acids increased by 1-6% after resolving overlapping peaks. Finally, the obtained percentages of saturated and unsaturated fatty acids were confirmed by reference reports.

Automated summary

The conventional method of fatty acid analysis using gas chromatography (GC) with polar capillary columns is not ideal due to high cost and sensitivity to water and oxygen. This study developed a method using GC/mass spectrometry (MS) with a nonpolar column and chemometric methods to accurately identify and quantify fatty acids. The fatty acid profiles of various seed oils were successfully identified and the resolution of overlapping peaks led to an increase in the total percentages of identified fatty acids. The obtained percentages of saturated and unsaturated fatty acids were confirmed by reference reports.