Identification of polyunsaturated triacylglycerols and C=C location isomers in sacha inchi oil by photochemical reaction mass spectrometry combined with nuclear magnetic resonance spectroscopy

Sacha inchi oil is derived from the seeds of Plukenetia volubilis L. and has great nutritional value due to its high contents of active polyunsaturated triacylglycerols (PUTAGs). In this study, we developed a methodology combined Paternò-Büchi reaction nanoelectrospray ionization mass spectrometry (PB-nanoESI-MS) and nuclear magnetic resonance (NMR) to identify C=C locations and isomers of PUTAGs in sacha inchi oil. Benzophenone was used as the PB reagent, and the optimized solvent composition (methanol:chloroform = 9:1) allowed for PUTAGs and their PB products to be detected with higher intensities. In addition, we made efforts to interpret the MS2 spectra for identification lipid species. A series of C57-PUTAGs and C59-PUTAGs were detected and identified via high-resolution PB-nanoESI-MS, and the predominant PUTAGs were TAG 18:1(Δ9)_18:3(Δ9,12,15)_18:3(Δ9,12,15) and TAG 18:2(Δ9,12)_18:2(Δ9,12)_18:3 (Δ9,12,15), which demonstrated that the PB-nanoESI-MS approach in this study provides help in promoting the development of structural determination of triacylglycerols in food chemistry.

• This study introduces an approach combining photochemical Paternò-Büchi reaction nanoelectrospray ionization mass spectrometry (PB-nanoESI-MS) with nuclear magnetic resonance (NMR) spectroscopy to determine the C=C positions and isomers in polyunsaturated triacylglycerols (PUTAGs) of sacha inchi oil.
• 13 C57-PUTAGs and 23 C59-PUTAGs mainly composed of linoleic and linolenic acids were identified in sacha inchi oil demonstrating that the approach developed in this study was helpful in evaluating the unique fatty acid profile and nutritional quality of sacha inchi oil.