Trifluoromethylphenyl-Induced Specific Acyl Chain Fragmentation in Liquid Chromatography Mass Spectrometry for Free...

Furan fatty acids (FuFAs) are special minor dietary lipids characterized by a furan ring structure, widely present in food sources, such as fish and plant oils. They exhibit potent antioxidant and anti-inflammatory activities, along with potential benefits for cardiovascular and metabolic health, with evidence suggesting that their physiological significance may surpass that of omega-3 fatty acids. However, the development of reliable methods for screening and structural elucidation of FuFAs in complex matrices has been hindered by the limited availability of chemical standards and their inherent photosensitivity. Herein, we propose a nontargeted liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS)-based method for the detection of free FuFAs using a trifluoromethyl-substituted phenyl bromoacetamide derivatization strategy. This labeling approach induces specific fragmentation during MS/MS analysis, generating diagnostic fragment ions derived from the furan moiety. Through comprehensive evaluation of various carboxylic acid derivatization reagents, including comparing retention behavior, isotopic patterns, fragmentation profiles, analytical performance in real samples, and theoretical calculations, the proposed method based on specific MS/MS fragmentation patterns was demonstrated to enable direct determination of FuFAs in complex lipid matrices, such as fish and plant oils. Furthermore, it facilitates the preliminary identification of key structural features of FuFAs, including the number of double bonds and substituent positions, and allows for structural assignment with minimal reliance on reference standards. This approach provides a straightforward, efficient, and data-simplified strategy for the structural identification of FuFAs in complex matrices.