Orthogonal functional group tagging combined with computational retention time prediction for discovering furan fatty...

Furan fatty acid (FuFA) exhibits antioxidant and anti-inflammatory properties, thereby reducing cardiovascular risks in humans. However, the availability of chemical standards for free FuFAs are limited. Some of them show poor tolerance toward acidic environments, elevated temperatures, and light exposure. Few accurate and efficient structural elucidation method has been developed for their non-targeted screening in complex matrices. This pilot study describes a novel approach that combines orthogonal functional group tagging with computational retention time (RT) prediction to identify potential free FuFA across different plant oil samples. The tagging of the furan ring skeleton and carboxylic group was achieved by direct condensation using two derivatization reagents, 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide (CMCT) and 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione (PTAD), respectively. The liquid chromatography-mass spectrometry (LC-MS) analysis of CMCT and PTAD derivatives of furan ring-containing carboxylic acids reveals that the RTs for CMCT derivative exceeded those of PTAD derivatives; CMCT derivatives generated [M-101.0841]⁺ and [M-125.0841]⁺ product ions, while PTAD derivatives produced [PTAD]^- and [M-43.9898]^- product ions. In the presence of straight-chain saturated fatty acids (C8:0-C20:0) within plant oil, computational RTs of putative 151 FuFAs located among C8:0-C20:0, facilitating the establishment of a predicted RT region mapping. It further identified the potential FuFA features picked out through the screening method to minimize false positive results. Although we ultimately not find any free FuFAs from the investigated samples, the results demonstrated that the procedure of FuFA screening dramatically mitigates false positive results during structural elucidation in the case of lack of chemical standards for comparison.