## 2 Results
### PCA Analysis of Major VOCs and EOs Constituents
alpyica_} \\ \hline  & & & & & & Monodeprene Hydrocarbons & & & & & & \\ \hline
5 & \(\alpha\)-Pinene & 945 & 942 & [33] & 98\% & 5.98 & - & 0.01 & 0.16 & 0.08 & - \\
10 & \(p\)-Pinene & 986 & 985 & [33] & 97\% & 0.80 & - & - & - & - & - \\
14 & \(p\)-Crrenne & 1033 & 1030 & [33] & 98\% & 0.50 & - & - & 0.01 & 0.02 & - \\
16 & \(L_{\text{minene}}\) & 1037 & 1035 & [33] & 97\% & - & - & - & 0.01 & 0.02 & - \\
20 & \((\hat{p})\)-de-cyreme & 1055 & 1054 & [33] & 98\% & - & - & - & - & - & - \\
22 & \(\gamma\)-Terpinene & 1067 & 1064 & [33] & 99\% & 1.18 & - & - & - & - & - \\ \hline \multicolumn{11}{c}{Total identified (\%)} & \multicolumn{6}{c}{8.46} & - & 0.01 & 0.18 & 0.12 & - \\ \hline \multicolumn{11}{c}{Fatty Acids and Fatty Acid Esters} & \multicolumn{6}{c}{} & \\ \hline
8 & Hexanoic (caprick) acid & 979 & 977 & [33] & 98\% & - & - & - & 0.02 & 0.06 \\
36 & Octanoic (caprick) acid & 1181 & 1180 & [33] & 96\% & - & - & - & 0.03 & 0.11 & 0.16 \\
44 & Nonanoic (caprick) acid & 1290 & 1290 & [33] & 97\% & - & - & - & - & 0.13 & 0.34 \\
49 & Methyl (decanoic) acid & 1330 & 1328 & [33] & 93\% & - & - & - & 0.34 & 0.34 & 2.82 & 0.91 \\
51 & Decanoic (caprick) acid & 1376 & 1377 & [33] & 96\% & 1.41 & - & - & - & 0.42 & - \\
53 & Ethly decanoate & 1399 & 1397 & [33] & 96\% & - & - & 1.85 & 1.18 & 2.56 & 3.90 \\
64 & Ethly dodecanoate (lamidi) acid & 1570 & 1570 & [33] & 97\% & - & - & - & 0.65 & - \\
65 & Tetradecanica (invited) acid & 1780 & [33] & 96\% & 31.92 & 7.27 & 97.01 & 37.12 & 75.11 & -4.20 \\
68 & Hexadec  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**No. ** & **Compound** & **RI** & **RI\({}_{\text{L}}\)** & \multicolumn{2}{c}{**RI\({}_{\text{L}}\)**} & \multicolumn{2}{c}{**Reference**} & **SI** & _L.psendoplilida_ B & _L.psendoplilida_ D & _L.psendoplilida_ T & _L.lispica_ V & _L.lispica_ Z &  
Figure 2: Average percentages of different groups of volatile organic compounds (VOCs) of the six investigated _Iris_ samples, obtained by three different methods: (**a**) headspace solid-phase microextraction (HS–SPME) using polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber, (**b**) HS–SPME using divinylbenzene/carboxylate/polydimethylsiloxane (DVB/CAR/PDMS) fiber, and (**c**) hydrodistillation (HD). IP B—_I. pseudopallida_ B; IP D—_I. pseudopallida_ D; IP T—_I. pseudopallida_ T; II V—_I. illylica_ V; II Z—_I. illylica_ Z; IA—_I. adriatica. Figure 3: Comparison of the contents of major compounds (content \(\geq\)2.0% in at least one sample) of the six investigated _Iris_ samples, obtained by three different methods: headspace solid-phase microextraction (HS-SPME) using polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber or divvinylbenzene/carboxene/polydimethylsiloxane (DVB/CAR/PDMS) fiber, or hydrodistillation (HD). IP B—_I. pseudopallida_ B; IP D—_I. pseudopallida_ D; IP T—_I. pseudopallida_ T; II V—_I. sillyrica_ V; II Z—_I. illivrica_ Z; IA—_I. adriatica_. The compounds that were found exclusively in the samples obtained by HD (essential oils) were the following (in alphabetical order): decanoic acid, diisobutyl phthalate, dodecosane, dodecanoic acid, hexadecanoic acid, (Z,Z)-octadeca-9,12-dienoic acid, \(\alpha\)-pinene, terpinen-4-ol, and tetradecanoic acid. Moreover, for investigated _Iris_ EOs, higher contents of myrtenol and \(\alpha\)-terpineol were also observed in comparison to the samples prepared by HS-SPME. Conversely, the presence of acetic acid, acetoin, butan-2,3-diol, ethanol, (furan-2-yl)methanol, hexanal, nervl formate, nonanal, nonan-2-one, pentanal, and 2-pentylfuran was not recorded in any of the samples obtained by HD (Figure 3). Only those compounds having a content of at least 2.0% in one or more samples were further included in the PCA analyses, while the rest were considered to be of minor importance and were consequentially excluded from the analyses.