Bio-phenols determination in olive oils: Recent mass spectrometry approaches

Extra virgin olive oil (EVOO) is largely used in Mediterranean diet, and it is also worldwide apprised not only for its organoleptic properties but also for its healthy effects mainly attributed to the presence of several naturally occurring phenolic and polyphenolic compounds (bio-phenols). These compounds are characterized by the presence of multiple phenolic groups in more or less complex structures. Their content is fundamental in defining the healthy qualities of EVOO and consequently the analytical methods for their characterization and quantification are of current interest. Traditionally their determination has been conducted using a colorimetric assay based on the reaction of Folin-Ciocalteu (FC) reagent with the functional hydroxy groups of phenolic compounds. Identification and quantification of the bio-phenols in olive oils requires certainly more performing analytical methods. Chromatographic separation is now commonly achieved by HPLC, coupled with spectrometric devices as UV, FID, and MS. This last approach constitutes an actual cutting-edge application for bio-phenol determination in complex matrices as olive oils, mostly on the light of the development of mass analyzers and the achievement of high resolution and accurate mass measurement in more affordable instrument configurations. After a short survey of some rugged techniques used for bio-phenols determination, in this review have been described the most recent mass spectrometry-based methods, adopted for the analysis of the bio-phenols in EVOOs. In particular, the sample handling and the results of HPLC coupled with low- and high-resolution MS and MS/MS analyzers, of ion mobility mass spectrometry and ambient mass spectrometry have been reported and discussed.