Tentative Characterization of Novel Phenolic Compounds in Extra Virgin Olive Oils by Rapid-Resolution Liquid Chromatography Coupled with Mass Spectrometry

Rapid-resolution liquid chromatography (RRLC) coupled with electrospray time-of-flight mass spectrometry (ESI-TOF-MS) and electrospray ion-trap multiple mass spectrometry (ESI-IT-MSn) has been applied to separate and characterize the phenolic compounds in five Spanish extra virgin olive oils. The phenolic compounds were characterized on the basis of accurate mass data according to studies by TOF-MS, and the fragmentation ions were further confirmed by IT-MSn whenever possible. Eight compounds, hydroxytyrosol (m/z 153), tyrosol (m/z 137), deacetoxy oleuropein aglycon (m/z 319), luteolin (m/z 285), pinoresinol (m/z 357), acetoxypinoresinol (m/z 415), apigenin (m/z 269), and deacetoxy ligstroside aglycon (m/z 303), all normally found in olive oil, were characterized in all five samples. Nevertheless, 30 uncommon phenolic compounds, including 10 ligstroside aglycon isomers (m/z 361) and two methyl oleuropein aglycon isomers (m/z 391), were also characterized in some of the five samples, and their fragmentation pathways were successfully elucidated.