## 1 Introduction
If the focus of the investigation is potent odorants, the ideal sampling system should comply for: (a) Appropriate/tunable extraction selectivity; (b) high extraction efficiency toward ultra-trace analytes with high odor potency; (c) mild interaction mechanisms (sorption/partition is preferable) that limit the formation of artifacts that may be induced during the thermo-desorption of volatiles at high temperatures; and (d) the full integration of all operation steps in the analytical system [19; 20; 24]. In this context, it would be interesting to compare the effectiveness of a number of gas-phase extraction procedures, more specifically headspace-sampling approaches, in delineating informative volatile patterns in extra-virgin olive oil. In fact, conventional SPME can show limited extraction capability for ultra-trace odorant analysis and/or suffer from headspace saturation [25], towards major HS components. Interesting solutions to enhance the sensitivity of the HS-SPME method have been presented by [PERSON] et al. [26], who proposed that cumulative multiple HS-SPME samplings be used in combination with a number of different fiber coatings, and followed by successive GC injections, which are delayed over time to achieve odor detection limits for GC-olfactometry (GC-O) screenings of wine aroma. More recently, [PERSON] et al. [25] have developed a dynamic headspace (DHS) sampling system that enables volatiles to be accumulated in SPME fibers, while also providing higher enrichment factors than the static headspace (SHS) approach and better aldehyde and alcohol recovery. The above-mentioned methods unfortunately have some limitations, such as automation difficultiesand, in the case of GC-O screenings, the fact that replicate analyses and dilution experiments are not possible. In this scenario, a systematic investigation of the different and complementary HS sampling methods, combined with high-resolution fingerprinting by GC \(\times\) GC coupled to time-of-flight mass spectrometry (TOF MS), would be of great interest, especially when the fingerprinting includes key-odorants that are responsible for the positive and negative sensory attributes of olive oil. In this study, a selection of HS approaches has been used to study the complex volatilome of a commercial EV olive oil. They include enriched SHS with: (a) SPME with a multi-polymer coating (divinylbenzene/carboxen/polydimethylsiloxane--DVB/CAR/PDMS), taken as the reference technique; (b) headspace sorptive extraction (HSSE) either with a single-material coating (PDMS) or dual-phase coating that combines PDMS/Carbopack [27] and PDMS/EG [28] (ethyleneglycol); (c) monolithic material sorptive extraction (MMSE) by octa-decyl silica combined with graphite carbon (ODS/CB); and (d) D-HS, with either PDMS foam, operating in partition mode, or Tenax TAtm, operating in adsorption mode. The coverage of both targeted and untargeted peak-region features that correspond to detectable analytes has been examined, while concentration factors (CF) have been calculated for a selection of informative analytes, including key-odorants and off-odors. Homolog-series relative ratios have also been calculated and information capacity has been discussed.