Comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC×GC-TOF MS): discrimination of Italian extra virgin olive oils (EVOOs) from different regions and exploration of high resolution (HR) mass spectrometry information

The volatile fraction of a food is generally characterized by high chemical dimensionality and compositional complexity. It encrypts information about sensorial quality, botanical/geographical origin, technological signature and can be of help for origin traceability and authentication. Comprehensive twodimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOF MS) is the most powerful analytical platform for an effective fingerprinting and profiling of complex volatiles mixtures. Both targeted and untargeted explorations can be conducted with high specificity and accuracy, providing that information from analytical dimensions is comprehensively yet actively used at the data processing level. However, the role of high-resolution (HR) MS, whose specificity is of tremendous help in several other fields (e.g., metabolomics, petroleomics) remain quite underexplored in food volatilomics. In the present study, the complex volatilome of high-quality extra-virgin olive oil (EVOO), is analyzed by headspace (HS) solid-phase microextraction (SPME) followed by GC×GC coupled to TOF MS operating at unit mass resolution or at high mass resolution (≥25 000 fwhm). The 4D data array is then processed by combined untargeted and targeted (UT) fingerprinting, by extracting peaks and peak-regions features for consistent pattern recognition. Supervised chemometrics (PLS-DA and OPLS-DA) helps in delineating diagnostic signatures with classification and discrimination potential toward oils produced in different Italian regions (Sicily, Tuscany, and Garda lake). The extra-dimension provided by HR-TOF MS, is examined in light of critical processing parameters (S/N thresholds, MS similarity match threshold etc.) and for the advantages provided in terms of classification specificity and sensitivity.