Analysis method and application of oxylipins based on chromatography-mass spectrometry technology

Accurate annotation of oxylipins is crucial not only for advancing our understanding of physiological processes in health and disease and identifying biomarkers, but also for food science, where oxylipins significantly impact food quality, safety, and flavor. However, a full view of oxylipins for early diagnosis needs further attention due to the lack of proper analytical methods, which may be attributed to the wide dynamic range, poor sensitivity, extreme molecular complexity, and limited commercially available standards of oxylipins. Here, we developed a novel method combining chemical derivatization (CD)-based retention index (RI) algorithm with feature tandem mass spectrometric fragmentation annotation (CD-RI-LC-MS/MS) for oxylipin identification and quantification. N,N-diethyl-1,3-diaminopropane (DEPA) rapidly labels oxylipins (within 0.5 min at room temperature) to enhance separation resolution and detection sensitivity. The RI algorithm calibrates retention time variances during LC-MS analysis, aiding oxylipin identification. MS/MS analysis of 58 DEPA derivatives of authentic oxylipin standards establishes tandem mass spectrometric feature fragmentation rules for unknown regio-isomer structure elucidation. Finally, a method based upon CD-RI-LC-MS/MS was established for profiling oxylipins from Standard Reference Material (SRM) 1950 human plasma samples. A total of 87 potential oxylipins including 12 unreported oxylipins were detected and identified. The CD-RI-LC-MS/MS method enables rapid and accurate oxylipin annotation in complex samples, aiding in the discovery of new oxylipins in biological processes and assessing lipid oxidation impacts in food, thus enhancing our understanding of their roles in metabolism and food quality.