Phospholipidome of extra virgin olive oil: Development of a solid phase extraction protocol followed by liquid chromatography-high resolution mass spectrometry for its software-assisted identification

The determination of phospholipids in olive oil is challenging due to their low concentration. For this reason, a comparison of two solid phase extraction procedures, namely weak anionic exchange (WAX) and graphitized carbon black (GCB), is presented for the enrichment of phospholipids. Analyses were performed by liquid chromatography-high resolution mass spectrometry (LC-HRMS) and lipids were identified by Lipostar software. Compared to the WAX solid phase extraction, GCB demonstrated the best performance and provided 82 identified phospholipids vs only 32. The final method was validated for some representative phospholipids, showing good repeatability and recovery (63-101%). High sensitivity was reached, with detection limits in the range 9-36 ng g-1, never reported before for phospholipids in olive oil. A semi-quantitative analysis indicated phosphatidic acids and phosphatidylglycerols as the most abundant species, both in number and concentrations. The GCB-LC-HRMS-Lipostar platform can be successfully applied for a comprehensive polar lipidomic characterization of olive oils.