UHPLC-APCI-MS Profiling of Triacylglycerols in Vegetable Oils—Application to the Analysis of Four North African Sesame Seed Varieties

Abstract

Here, we describe an isocratic ultra-high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (UHPLC-APCI-MS) method for the characterization and the quantification of triacylglycerols (TAGs) in vegetable oils. The linearity and the precision of the method are validated, and the limits of detection are estimated. The APCI-MS detector shows a linear response from 1 to 1000 μg/mL, and the correlation coefficients (r2) obtained for standards TAGs exceed 0.995. As compared to previous methods, the proposed method is rapid, simpler, and more sensitive. The limits of detection estimated for several standard TAGs varies from 0.03 to 0.05 injected nanograms (6 to 10 μg/L). The application of the proposed method to the analysis of sesame oil allowed us to unambiguously identify 30 TAG species whereas previous methods have detected 19 TAGs, at the most. Among vegetable oils, sesame oil became an attractive target for adulteration due to its high commercial value. Most of the previous studies of TAG profiles of sesame oils had been devoted to the analysis of sesame oils originating from Asia and some Sub-Saharan countries. To the best of our knowledge, the TAG profiles of sesame oils from other origins are still unknown. The results we obtained for the four Tunisian sesame seed varieties clearly indicate that sesame oils can be classified according to their equivalent carbon number differences (ΔECN) with some rules similar to those required for olive oils.