Framework for the in-depth characterization of food triacylglycerols using liquid chromatography coupled to cyclic ion mobility mass spectrometry

Triacylglycerols (TAGs), a major lipid class in foods, exist in various isomeric forms, such as sn-positional, cis/trans, acyl chain length, double bond positional, and mixed type isomers. However, separating these isomers remains challenging with conventional analytical methodologies. In this study, we propose a comprehensive framework for the in-depth characterization of TAGs in vegetable oils using liquid chromatography-cyclic ion mobility-mass spectrometry (LC-cIMS-MS) approaches. cIMS-MS has indeed recently emerged as a promising technique for the separation of TAG isomers. In this study, two parameters were evaluated for the identification of TAG isomers using cIMS-MS, i.e., their fragmentation ratios and collisional cross sections (CCS). These parameters were combined with our previously established trends in drift time order to identify TAG isomers in vegetable oils. This showed that the relative influence of TAG structural features on drift time is as follows (from high to low): (1) degree of unsaturation of the fatty acid(s) on sn-1/3, (2) acyl chain length on sn-1/3, (3) cis/trans configuration, and (4) double bond (DB)-position. When applied to sunflower and olive oils, our framework allowed the characterization of 37 and 38 TAGs, respectively, including 3 to 8 groups of TAG isomers. This study highlights the potential of cIMS-MS for providing an in-depth characterization of TAGs and their isomers in real food samples.