## 2 Results and Discussion
### Reference Chemical Profiles of Genuine Essential Oils  
Generally, the reference profile should include the minimum, average and maximum percent normalised area values for each selected marker compound, which should be calculated using a sufficient (significantly representative) number of controlled genuine samples. Figure 1 shows the GC-MS patterns of genuine bergamot, laverder and tea tree EO. These EO were characterised mostly by monoterpenes/monoterpenoids and sesquiterpenenes/sesquiterpenoids; each EO profile presented some predominant compounds (e.g., linalool and linalyl acetate in bergamot and laverder EO and 4-terpineol and \(\gamma\)-terpinene in the tea tree EO), together with other relatively minor compounds. Table 1 reports the composition of the investigated EO in terms of the normalised relative abundance (minimum, maximum and average % areas, together with the standard deviation values) of the characteristic marker compounds determined by analysing twenty  
Figure 1: GC-MS patterns of genuine bergamot, laverder and TTO EO. Legend: (1) \(\alpha\)-pinene, (2) sabinene, (3) \(\beta\)-pinene, (4) 3-octanone, (5) \(\beta\)-mycrene, (6) \(\alpha\)-phellandrene, (7) \(\alpha\)-terpinene, (8) \(p\)-cymene, (9) limone, (10) 1,8-cineole, (11) _cis_-\(\beta\)-ocimene, (12) _trans_-\(\beta\)-ocimene, (13) \(\gamma\)-terpinene, (14) \(\alpha\)-terpinolene, (15) linalool, (16) 1-octen-3-yl acetate, (17) camphor, (18) lavandulol, (19) 4-terpineol, (20) \(\alpha\)-terpineol, (21) neral, (22) linalyl acetate, (23) granial, (24) lavandulyl acetate, (25) neryl acetate, (26) geranyl acetate, (27) _trans_-\(\beta\)-caryophyllene, (28) aromadendrene, (29) _trans_-\(\beta\)-farresene and (30) \(\beta\)-bisabolene. For the analysis conditions, see the main text. genuine batches for each EO. Table 1 also reports the Italian/European Pharmacopoeia % area ranges. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{_Citrus limon_ **(L) Osbeck**} \\ \hline  & **Compounds** & **1\({}^{\mathbf{t}}\)sexp** & **1\({}^{\mathbf{t}}\)slit** & **Min** & **Max** & **Average** & \(\mathbf{\sigma}\) & **Ital. Ph. ** \\ \hline
2 & sabinene & 976 & 976 & 0.8 & 1.0 & 0.9 & 0.1 & 0.5–2.0 \\
3 & \(\beta\)-pinene & 978 & 980 & 5.6 & 6.9 & 6.5 & 0.4 & 5.0–10.0 \\
5 & \(\beta\)-myrcene & 992 & 991 & 0.7 & 1.5 & 1.0 & 0.2 & \\
7 & \(\alpha\)-terpinene & 1018 & 1018 & 0.1 & 0.2 & 0.1 & 0.1 & \\
8 & \(p\)-\(\zeta\)mene & 1028 & 1026 & 0.2 & 0.7 & 0.4 & 0.2 & \\
9 & limonene & 1031 & 1031 & 34.3 & 40.9 & 37.8 & 2.3 & 30.0–50.0 \\
12 & _trans_-\(\beta\)-ocimene & 1051 & 1050 & 0.1 & 0.2 & 0.1 & 0.1 & \\
13 & \(\gamma\)-terpinene & 1061 & 1062 & 5.3 & 8.0 & 6.7 & 0.9 & 6.0–18.5 \\
14 & \(\alpha\)-terpinolene & 1089 & 1088 & 0.3 & 0.6 & 0.3 & 0.1 & \\
15 & linalool & 1100 & 1098 & 9.6 & 12.3 & 10.7 & 0.8 & 6.0–15.0 \\
21 & neral & 1243 & 1240 & 0.1 & 0.3 & 0.2 & 0.1 & \\
22 & linaly acetate & 1264 & 1257 & 30.0 & 35.8 & 31.5 & 1.6 & 23.0–35.0 \\
23 & gerani & 1273 & 1270 & 0.1 & 0.5 & 0.3 & 0.1 & max 0.5 \\
25 & neryl acetate & 1369 & 1365 & 0.3 & 0.8 & 0.5 & 0.1 & \\
26 & geranyl acetate & 1386 & 1383 & 0.3 & 0.7 & 0.4 & 0.1 & 0.1–0.7 \\
27 & _trans_-\(\beta\)-caryophyllene & 1419 & 1418 & 0.1 & 0.6 & 0.3 & 0.1 & 0.2–0.5 \\
30 & \(\beta\)-bisabolene & 1510 & 1509 & 0.1 & 0.4 & 0.2 & 0.1 & \\ \hline \hline \multicolumn{6}{c}{_Lavandula angustifolia_ **Mill. **} \\ \hline  & **Compounds** & **1\({}^{\mathbf{t}}\)sexp** & **1\({}^{\mathbf{t}}\)slit** & **Min** & **Max** & **Average** & \(\mathbf{\sigma}\) & **Eur. Ph.