Incorporating cIMS in an analytical framework for the in-depth characterization of food triacylglycerols

Characterization of the triacylglycerol (TAG) composition of food oils is challenging, in particular due to the presence of isomers. The main bottleneck is the incomplete separation of isomeric TAGs in liquid chromatography coupled to mass spectrometry (LC-MS), hindering identification because of mixed fragmentation spectra. In this study, the potential of adding cyclic ion mobility spectrometry (cIMS) as an additional dimension of separation in LC-MS analysis of food oils was explored to improve TAG isomer characterization. An analytical framework was created to achieve TAG isomer characterization by combining gas chromatography-MS (GC-MS), LC-MS, and cIMS-MS. TAG standards were used to evaluate the best option(s) for TAG isomer identification: fragmentation ratios, which can only be determined from pure fragmentation spectra obtained after separation of isomers in cIMS-MS; collisional cross section (^cIMSCCS_N2) values; or a combination thereof. Fragmentation ratios from pure fragmentation spectra yielded the strongest approach for isomer identification, as some TAG isomers were too close in ^cIMSCCS_N2 for confident identification. Finally, using this framework, we identified 21 TAG isomers in sunflower and olive oils, 11 of which would not have been identified without the use of cIMS-MS. Overall, this study demonstrates the potential of the extra separation dimension provided by cIMS and its complementarity with classical GC- and LC-MS analyses.