Stereoselective Reaction Enabling Simultaneous Analysis of Carbon-Carbon Double-Bond Configuration and the Position of Monounsaturated Fatty Acids through UHPLC-ESI-MRM-MS.

Monounsaturated fatty acids (MUFA) are an important class of nutrients and are involved in lipid metabolism. The positions of the C=C bond and cis-trans isomerism have a significant influence on their physiological activity. However, simultaneously detecting these two structural properties has been challenging due to multiple isomers of MUFA. In this study, we developed a method that involved an -aminophthalimide (PhthNH) derivatization of the C=C bond in MUFA, followed by analysis using ultrahigh-performance liquid chromatography-electrospray ionization-multiple reaction monitoring mass spectrometry (UHPLC-ESI-MRM-MS) technology to achieve analysis of cis-trans isomers and positional isomers of the C=C bond. The derivatives of cis-trans isomers of the C=C bond were well separated in UHPLC, and their corresponding C=C bond positions were deduced from characteristic fragment ions in tandem mass spectrometry. With our method, we found MUFA with different double-bond positions and cis-trans isomers in several samples, including mouse kidney, butter, etc., achieving qualitative analysis and relative quantitation. This method is expected to be applied by more researchers in lipidomics studies in the future.