Efficient Strategy for Characterization and Quantification of Polyunsaturated Lipids by Microwave-Assisted MMPP Epoxidation

• Published in: Analytical chemistry (Washington) Vol. 96; no. 28; pp. 11189 - 11197
• Main Authors: Huang, Longhui, Huang, Minhan, Zhou, Ting
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 16.07.2024
• Subjects: Animals; Biological activity; Biomarkers; Carbon; Chemical reduction; Chromatography, Liquid - methods; Diabetes; Diabetes mellitus; Effectiveness; Epoxidation; Epoxy Compounds - chemistry; Fatty acids; Fatty Acids, Unsaturated - analysis; Fatty Acids, Unsaturated - blood; Fatty Acids, Unsaturated - chemistry; Ion pairs; Irradiation; Lipids; Liquid chromatography; Magnesium; Male; Mass spectra; Mass spectrometry; Mass spectroscopy; Microwave radiation; Microwaves; Physiology; Rats; Rats, Sprague-Dawley; Reagents; Scientific imaging; Structural analysis; Structure-function relationships; Tandem Mass Spectrometry - methods
• ISSN: 0003-2700; 1520-6882; 1520-6882
• DOI: 10.1021/acs.analchem.4c00410

Lipids play integral roles in biological processes, with carbon–carbon double bonds (CC) markedly influencing their structure and function. Precise characterization and quantification of unsaturated lipids are crucial for understanding lipid physiology and discovering disease biomarkers. However, using mass spectrometry for these purposes presents significant challenges. In this study, we developed a microwave-assisted magnesium monoperoxyphthalate hexahydrate (MMPP) epoxidation reaction, coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), to analyze unsaturated lipids. Microwave irradiation expedited the MMPP epoxidation, achieving complete derivatization in 10 min without byproducts. A diagnostic ion pair, displaying a 16 Da mass difference, effectively identified the location of the CC bond in mass spectra. Microwave irradiation also significantly facilitated the epoxidation reaction of polyunsaturated lipids, achieving yields greater than 85% and yielding a complete epoxidation product. This simplifies chromatographic separation and aids in accurate quantification. Additionally, a purification process was implemented to remove excess derivatization reagents, significantly reducing mass spectrometry response suppression and enhancing analytical reproducibility. The method’s effectiveness was validated by analyzing unsaturated lipids in rat plasma from a type I diabetes model. We quantified nine unsaturated lipids and characterized 42 fatty acids and glycerophospholipids. The results indicated that unsaturated fatty acids increased in diabetic plasma while unsaturated glycerophospholipids decreased. Furthermore, the relative abundances of Δ9/Δ11 isomer pairs also exhibited a close association with diabetes. In conclusion, microwave-assisted MMPP epoxidation coupled with LC-MS/MS provides an effective strategy for characterization and quantification of polyunsaturated lipids, offering deeper insight into the physiological impact of unsaturated lipids in related diseases.