Tentative identification of phenolic compounds in olive pomace extracts using liquid chromatography-tandem mass spectrometry with a quadrupole-quadrupole-time-of-flight mass detector.

The reuse of agronomical residues is a pending goal for sustainable agriculture. Particular residues in olive-oil-producing countries are leaves, wastewater, and olive pomace. Olive leaves and wastewaters have been previously characterized by isolation of the phenolic fraction. However, olive pomace has not yet been qualitatively characterized as a source of phenols. Olive pomace extracts were obtained using superheated solvent extraction using 50:50 (v/v) water/ethanol as a leaching mixture at 160 °C. The extracts were analyzed by liquid chromatography coupled to tandem mass spectrometry using a quadrupole-quadrupole-time-of-flight (QqTOF) hybrid mass analyzer (R = 25,000-45,000). Qualitative analysis was supported upon measurement of accurate masses for precursor and product ions as well as their isotopic distribution. Identification was focused on the main families of phenolic compounds present in extra virgin olive oil. The potential of this residue as a rich source of phenols with antioxidant properties has been proven.