EXPLORING THE POTENTIAL OF ADDING “EXTRA-DIMENSIONS” TO THE EXTRA VIRGIN OLIVE OIL VOLATILES FINGERPRINTING BY GC×GC-TOF MS AND SOFT IONIZATION

Comprehensive two-dimensional gas chromatography (GC×GC) is the most effective multidimensional separation technique for in-depth investigations of complex samples of volatiles (VOC) in food. It enables highly informative fingerprinting and, if Mass Spectrometry is adopted at the detection level, it has the intrinsic potential of a detailed profiling giving access to the higher level of information encrypted in the peculiar distribution of sample’s components. Time of Flight Mass Spectrometry (ToF-MS) with soft electron ionization adds an additional dimension to the analysis thereby enabling more confident identifications but also new challenges for the data processing. The possibility to operate by switching between hard (-70 ev) and soft ionization (12, 14 and 16 eV) generates complementary MS signatures (about each component and for each 2D pattern), increasing the dimensionality of the analysis. Soft and hard ionization spectra are obtained simultaneously allowing comprehensive and highly reliable characterization of complex fractions also easing the speciation of isomers. In this study the focus is on the complex volatile fraction from Extra Virgin Olive oils from different botanical and geographical origin and obtained from fruits at different ripening stage. The analytical strategy combines extra-dimensions from volatiles sampling by High Concentration Capacity (HCC) sample preparation (Head Space Solid Phase Microextraction with different polymer(s) combinations) to analytes detection by soft ionization at 12 and 14 eV. The distribution of olives ripening indicators, key-odorants responsible of positive attributes and off-odors for defects assessment is studied; fingerprints from different samples are compared to critically evaluate the beneficial role of adding extra-dimension to the analysis.