Separation of triacylglycerol isomers by cyclic ion mobility mass spectrometry

Abstract: Triacylglycerols (TAGs) are the most abundant lipid class in foods. They consist of three fatty acid chains esterified on a glycerol backbone and are often present in various isomeric forms. These include 1/ sn- positional isomers, 2/ chain length isomers, 3/ double bond positional isomers, and 4/ cis-trans conformational isomers. Elucidating these complex isomeric mixtures is of great interest as different isomers can have distinct properties, such as digestibility or oxidative stability. However, this remains so far quite challenging and time-consuming. In this study, we evaluated the potential of cyclic ion mobility mass spectrometry (cIMS-MS), a novel state-of-the-art technique, on the separation and identification of all types of TAG isomers. The influence of different adducts (Li, NH₄, Na, and K) was also investigated. Using direct infusion of analytical standards, we successfully separated most types of TAG isomers; all adducts were shown to be useful for such separation. These results highlight the great potential of cIMS-MS for the separation and identification of various TAG isomers. In addition, hyphenation with LC could provide a powerful tool to elucidate complex TAG isomer mixtures present in foods.