Rapid screening of oxidized metabolites of unsaturated fatty acids in edible oil by NanoESI-MS/MS

A rapid characterization method is urgently required because hydroperoxyl/hydroxyl group position of lipid hydroperoxides/hydroxides is extremely unstable. In this study, eight hydroperoxides/hydroxides derived from standards (9-HPODE/HODE, 10-HPODE/HODE, 12-HPODE/HODE, and 13-HPODE/HODE) were identified by the established nano electrospray ionization coupling with tandem mass spectrometer (NanoESI-MS/MS) and then verified by LC-TOF-MS/MS. Results showed that hydroperoxides/hydroxides of unsaturated fatty acid (UFAs) could generate various characteristic fragments through CID fragmentation pathways and the qualitative ion fragments largely preferred the carbonyl-side alpha-cleavage of C-C adjacent to hydroperoxyl/hydroxyl. Without extraction enrichment, this method could further be used for the instantaneous discrimination of UFAs hydro-peroxides/hydroxides in soybean oil, corn oil, peanut oil, rapeseed oil and grass carp oil (<= 4 min/per sample). In conclusion, this method could be performed as a Point of Care Testing (POCT) method for discriminating dominant lipid hydroxides/hydroperoxides rapidly and shed specific insights to conventional lipid oxidation research.

Automated summary

A rapid characterization method was developed for the unstable hydroperoxyl/hydroxyl group position of lipid hydroperoxides/hydroxides. Eight hydroperoxides/hydroxides derived from standards were identified using nano electrospray ionization coupling with tandem mass spectrometer (NanoESI-MS/MS) and verified by LC-TOF-MS/MS. The method could be used for the instantaneous discrimination of UFAs hydro-peroxides/hydroxides in various edible oils without extraction enrichment (<= 4 min/per sample), providing specific insights to conventional lipid oxidation research.