## 2 Results and Discussion
### Optimisation of SPME Extraction Conditions

Table 2: _Cont._  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Compound Name** & **Rt** & **Rexp** & **RI** & \begin{tabular}{c} **Chania** \\ **Mean** \\ **(n = 17)** \\ \end{tabular}  & \(\pm\)**SD** & \begin{tabular}{c} **Heraklion** \\ **Mean** \\ **(n = 26)** \\ \end{tabular}  & \(\pm\)**SD** & \ \begin{tabular}{c} **Lasithi** \\ **Mean** \\ **(n = 10)** \\ \end{tabular}  & \(\pm\)**SD** & \begin{tabular}{c} **Rethymon** \\ **Mean** \\ **(n = 10)** \\ \end{tabular}  & \(\pm\)**SD** \\ \hline
3-Carene & 8.79 & 1018 & 1018 & 0 & 0.01 & 0.01 & 0.01 & 0 & 0.01 & 0.02 & 0 \\ \hline (Z)-beta-Ocimene & 9.29 & 1050 & 1048 & 0.05 & 0.02 & 0.07 & 0.03 & 0.07 & 0.03 & 0.09 & 0.02 \\ \hline o-Cymene & 8.95 & 1031 & 1037 & 0.14 & 0.48 & 0.2 & 0.59 & 0 & 0.54 & 1.33 & 0 \\ \hline d-Limonene & 9.02 & 1035 & 1041 & 0.7 & 1.83 & 0.99 & 3.29 & 0.1 & 2.87 & 0.19 & 4.33 \\ \hline (+)-2-Carene & 9.04 & 1035 & 1031 & 0 & 0 & 0.06 & 0.23 & 0 & 0.23 & 0.92 & 0 \\ \hline Neral & 12.61 & 1247 & 1244 & 0 & 0.01 & 0 & 0.01 & 0 & 0.01 & 0 & 0.01 \\ \hline Citral & 13.07 & 1276 & 1276 & 0 & 0.01 & 0 & 0.02 & 0 & 0.02 & 0 & 0.02 \\ \hline (+)-Cyclosativene & 14.67 & 1384 & 1368 & 0 & 0 & 0.01 & 0.01 & 0 & 0.01 & 0.01 & 0.01 \\ \hline Copaene & 14.73 & 1388 & 1392 & 0.03 & 0.01 & 0.05 & 0.03 & 0.06 & 0.03 & 0.1 & 0.02 \\ \hline Eremophilene & 16.34 & 1505 & 1503 & 0.01 & 0.01 & 0.01 & 0.01 & 0.01 & 0.01 & 0.01 \\ \hline alpha-Farnesene & 16.39 & 1509 & 1509 & 0.05 & 0.03 & 0.06 & 0.03 & 0.05 & 0.03 & 0.05 & 0.07 \\ \hline Kessane & 16.94 & 1551 & 1530 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ \hline Liguloxide & 17.07 & 1561 & 1533 & 0 & 0 & 0.01 & 0.01 & 0 & 0.01 & 0 & 0.01 \\ \hline \multicolumn{2}{c}{**Others**} & & & & & & & & & & & \\ \hline
2-Methylpentane & 1.62 & 588 & 573 & 0.04 & 0.03 & 0.04 & 0.02 & 0.03 & 0.02 & 0.03 & 0.01 \\ \hline
3-Methylpentane & 3.39 & 741 & 748 & 0.05 & 0.03 & 0.07 & 0.03 & 0.08 & 0.03 & 0.09 & 0.03 \\ \hline Toluene & 3.86 & 770 & 771 & 0.17 & 0.1 & 0.19 & 0.21 & 0.13 & 0.24 & 0.06 & 0.2 \\ \hline
1-Octene & 4.25 & 794 & 792 & 0.17 & 0.1 & 0.15 & 0.08 & 0.14 & 0.07 & 0.21 & 0.05 \\ \hline Octane & 4.42 & 803 & 800 & 1.64 & 0.78 & 2.13 & 1.08 & 2.28 & 1 & 3.86 & \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Compound Name** & **Rt** & **Rlev** & \begin{tabular}{c} **RI** \\ **Lit** \\ \end{tabular} & \begin{tabular}{c} **Chania** \\ **Mean** \\ **(n = 17)** \\ \end{tabular} & \(\pm\)**SD** & \
\begin{tabular}{c} **Heraklion** \\ **Mean** \\ **(n = 26)** \\ \end{tabular} & \(\pm\)**SD** &
\begin{tabular}{c} **Lasithi** \\ **Mean** \\ **(n = 10)** \\ \end{tabular} & \(\pm\)**SD** \\ \hline \((E)\)-4,8-Dimethyl-1,3,7- & & 10.11 & 1096 & 1098 & 0.06 & 0.02 & 0.09 & 0.04 & 0.09 & 0.04 & 0.05 & 0.03 \\ \hline Methyl benzoate & 10.27 & 1104 & 1106 & 0.04 & 0.01 & 0.05 & 0.02 & 0.05 & 0.02 & 0.03 & 0.01 \\ \hline Naphthalene & 11.88 & 1201 & 1206 & 0.06 & 0.24 & 0 & 0.15 & 0.01 & 0.13 & 0 & 0 \\ \hline \((E)\)-2-Dodecene & 11.96 & 1206 & 1206 & 1.78 & 0.32 & 2.14 & 0.64 & 2.02 & 0.67 & 1.05 & 0.58 \\ \hline
1-Dodecene & 12.96 & 1270 & 1265 & 0.04 & 0.02 & 0.04 & 0.02 & 0.03 & 0.02 & 0.07 & 0.02 \\ \hline Pentadecane & 16.28 & 1501 & 1500 & 0.01 & 0.01 & 0 & 0.01 & 0 & 0.01 & 0.02 & 0.01 \\ \hline
2,4-Di-tert-butylphenol & 16.44 & 1513 & 1517 & 0.02 & 0.01 & 0.02 & 0.01 & 0.01 & 0.01 & 0.01 \\ \hline Total & & & 108.1 & & 81.42 & & 92.67 & & 85.77 & \\ \hline C5 & & & 13.6 & & 11.3 & & 12.35 & & 12.06 & \\ \hline C6 & & & 54.37 & & 42.93 & & 47.86 & & 42.74 & \\ \hline C5 + C6 & & & 67.97 & & 54.22 & & 60.21 & & 54.8 \\ \hline \hline \end{tabular}
\begin{tabular}{c c c c c c c c} \hline \hline
**Rt: Retention Time, LS.: Internal Standard, Rlex: Retention Index experimental, Rllit: Retention Index literature, SD: Standard Deviation.**  
\end{table} 
Table 2: _Cont._  
Figure 3: Major VOCs identified in the TIC of a QC olive oil sample analysed with optimised HS-SPME/GC-MS conditions. Upper in the insets, zoomed areas are shown. The identified components are given in numbers.