## 2 Results and Discussion
### Commercial EO Adulterated with Vegetable Oils  
As mentioned previously, the addition of vegetable oil produces a dilution of the EO that does not affect the qualitative GC profile but results in a decrease of the absolute amounts of the markers. Figure 3 shows the GC-MS patterns of both genuine and spiked on purpose lavender EO (analysed with an oven temperature program up to 300 \({}^{\circ}\)C). The GC patterns clearly indicate the absence of peaks due to vegetable oils, and it is perfectly superimposable from a qualitative point of view. However, the profile of the spiked sample presents peaks of lower intensity, maybe indicative of a dilution effect due to the presence of a heavy vegetable oil. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & & & \multicolumn{6}{c}{_Citrus limon EO_} & \multicolumn{6}{c}{_Lavendula angusifolia EO_} \\ \hline  & & & **Genuine** & & \multicolumn{2}{c}{**Spiked**} & \multicolumn{2}{c}{**Com. Sample**} & \multicolumn{2}{c}{**Genuine**} & \multicolumn{2}{c}{**Spiked**} & \multicolumn{2}{c}{**Com. Sample**} & \multicolumn{2}{c}{**C-1 EO**} \\ \hline  & & & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** \\ \hline linalool & 1100 & 1098 & 11.4 & 0.1 & 15.2 & 0.1 & 15.0 & 30.0 & 0.2 & 38.8 & 0.1 & 39.2 & 0.3 \\ linalyl acetate & 1260 & 1259 & 27.5 & 0.2 & 32.6 & 0.4 & 33.1 & 35.0 & 0.4 & 42.8 & 0.1 & 42.9 & 0.5 \\ \hline  & & & \multicolumn{6}{c}{_Melalenca alternifolia_ EO} \\ \hline  & & & **Australian** & & \multicolumn{2}{c}{**Mixed**} & \multicolumn{2}{c}{**Com. Sample**} & \multicolumn{2}{c}{**C-1 EO**} & \multicolumn{2}{c}{} \\  & & & & **Origins** & \multicolumn{2}{c}{**CT-1 EO**} & \multicolumn{2}{c}{} \\ \hline  & & **I\%** & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** & & & \\ \hline
4-terpineol & 1178 & 1177 & 44.0 & 0.6 & 42.6 & 0.1 & 41.4 & 0.6 & & & & & \\ \(\alpha\)-terpineol & 1190 & 1189 & 3.0 & 0.1 & 4.8 & 0.04 & 5.0 & 0.7 & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Normalised relative % abundance of linalool, linaly acetate, 4-terpineol and \(\alpha\)-terpineol in genuine, spiked and commercial samples of bergamot, lavender and TTO EO obtained with conventional GC. One of the commercial lavender EO samples (CL-2 EO) showed normalised peak area intensities of the selected markers significantly lower than those observed in genuine EO. The sample was submitted to the European Pharmacopoeia test to detect fatty oils [1] by putting a drop of the EO onto filter paper and a slight translucent spot after 24 h was evidenced. The conventional GC and enantioselective GC analyses did not provide results suitable to measure the % of adulteration; therefore, a true quantitative analysis was required. A  
Figure 3: GC-MS patterns of both genuine and spiked on purpose lavender EO (analysed with an oven temperature program up to 300 \({}^{\circ}\)C). Figure 2: Linalool and linalyl acetate in a genuine and an adulterated bergamot EO analysed with a 2,3 DE6 TBDMS-\(\beta\)-CD chiral column phase. series of experiments were carried out to evaluate the reliability of this approach by adulterating the three oils of this study with different amounts of vegetable oils to confirm the % adulteration experimentally, although only one suspected commercial lavelender sample (CL-2 OE) was the object of investigation. The data obtained for the commercial and adulterated EO were the same as those calculated in the genuine samples and already reported in Table 1 (data not shown, as it is redundant), driving us to perform a true quantitative analysis. Table S4 reports the equations for the calibration curves that were obtained with an external standard approach and used to quantitate the marker compounds, together with their correlation coefficient and the selected range of concentrations. Table 4 reports the absolute concentrations of the selected markers in the genuine, the spiked and the commercial lavelender oil EO under investigation.