## 3 Results and Discussion
### Static HS and HS-SPME-GC-MS Analysis of the VOC Profile  
The static HS-GC-MS analysis allowed the exclusive detection of the monoterpenes fraction (Table S3 in Supplementary Materials), that was disentangled providing a detailed VOC profile of the analyzed LO with the relevant percentage composition. In substantial agreement with the literature [60], the most significant components (red bars in Figure 4) are alpha-pinene (43.1%), beta-myrcene (34.6%), alpha- and beta-phellandrene (7.9 and 4.3%, respectively), and finally sabinene (4.4%). All the other monoterpenes, detected in traces (<0.5%), are listed in Table S3. The presence of the monoterpenes class of compounds encourages the potential application of a formulation LO-based as topical agent, since its involvement in the dermal re-epithelialization process has already been pointed out [61]. Static HS sampling proved to be extremely useful to take the actual snapshot of the vapor phase in equilibrium with the liquid oil at a temperature which is selected as a compromise between the maximization of the analytic efficiency and the limit of the analytes thermolability. Complementarily, the exposure of a DVB/CAR/PDMS fiber into the oil headspace, i.e., HS-SPME-GC-MS, provided a preconcentration of the vapor phase which is mandatory to reveal less volatile and/or more diluted compounds. The emerging picture is necessarily more informative than the static HS one because, on the methodological standpoint, the selectivity of the fiber-coating introduced a bias in the headspace fingerprinting, but provided the identification and quantification of metabolites that were invisible to other techniques. Indeed, the HS-SPME-GC-MS technique allowed to detect 47 compounds (Table S4), mostly represented by monoterpenes (96%), according to the VOC profile that emerged in the static HS analysis, that exhibited a definite lower sensitivity (13 detected compounds). Within this class of VOC, significant differences were found in the static HS vs. HS-SPME distributions, as reported in Figure 4, where there is a clear inversion of the myrcene/alpha-pinene ratios (0.8 and 2.6, respectively) indicating a higher affinity of the fiber coating toward myrcene. A further contribution to the VOCs profile emerging from the HS-SPME sampling consists of sesquiterpene detection (Figure 5 and Table S4). In addition to their low relative abundance (17 compounds, about 1.5% of the total chromatogram area), sesquiterpenes represent the second most abundant class of compounds detected in the HS-SPME-GC-MS analysis. Beta-elemene, alpha-humulene and alpha-cubebene are the most representative sesquiterpenes in the LO, followed by gamma-muurolene-alpha-farnesene, 9-epi-E-caryophyllene and its diastereoisomer E-caryophyllene. The antifungal and anti-bacterial activity of sesquiterpenes was extensively reported by [PERSON] et al. (2016). Very low abundance (<0.1%) of aldehydes (pentanal and hexanal), ketones (heptyl-methyl-ketone and undecan-2-one) and FAE (isobutyl- and isopentyl hexanoate and methyl-decanoate) were also detected (Table S4). The comparison between the two sampling procedures herein proposed points to their strict complementarity that provides both the actual composition and the selectively enhanced profile of the VOCs.  
Figure 4: Percentage areas of the most concentrated monoterpenes detected through static HS (red bars) and HS-SPME-GC-MS (blue bars) analyses.