## 2 Results and Discussion
### The Headspace C. erythraea _VOC Composition_
\begin{table}
\begin{tabular}{l l c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Compound**} & \multicolumn{2}{c}{**RI**} & \multicolumn{2}{c}{**RI**} & \multicolumn{2}{c}{**Peak area (\%)**} \\  & & **HP-5 MS** & **HP-FFAP** & **C** & **D** & **E** \\ \hline
43. & \(\alpha\)-Muurolene & 1506 & 1745 & 0.3 & - & - \\
44. & Pentadecane & 1500 & / & - & 1.1 & - \\
45. & \(\beta\)-Bisabolene & 1515 & 1743 & 0.2 & 0.7 & - \\
46. & \(\gamma\)-Cadinene & 1521 & 1814 & 0.3 & - & - \\
47. & \(\delta\)-Cadinene & 1531 & 1777 & 0.8 & 1.9 & - \\
48. & Myristicin & 1533 & 2271 & - & - & 0.3 \\
49. & \(\alpha\)-Calacorene & 1551 & 1938 & 0.3 & 0.8 & - \\
50. & Spathulenol & 1586 & 2088 & 1.3 & - & 0.9 \\
51. & Caryophyllene oxide & 1589 & 1998 & 0.9 & - & 1.7 \\
52. & Dodecanoic acid & 1594 & / & 1.0 & - & - \\
53. & Hexadec-1-ene & 1598 & / & - & 1.7 & - \\
54. & Viridiffololol & 1599 & 2059 & 0.8 & - & 1.1 \\
55. & Hexadecane & 1600 & 1600 & - & 1.0 & - \\
56. & \(\alpha\)-Cadinol & 1665 & / & 0.7 & - & 1.6 \\
57. & Ethyldibenzothiophene (isomer I) \({}^{*}\) & 1682 & / & 0.7 & - & - \\
58. & Acorenone B & 1696 & / & 0.9 & - & 1.2 \\
59. & Heptadecane & 1700 & 1700 & 0.3 & 1.1 & - \\
60. & Farnesol \({}^{*}\) & 1710 & / & 0.5 & - & 0.6 \\
61. & Pentadecanal & 1723 & / & 0.5 & - & 0.8 \\
62. & Chromolainen & 1727 & / & - & 2.1 & - \\
63. & Ethyldibenzothiophene (isomer II) \({}^{*}\) & 1729 & / & - & 0.6 & - \\
64. & Ethyldibenzothiophene (isomer III) \({}^{*}\) & 1734 & / & 0.2 & 1.5 & - \\
65. & Aristolone & 1767 & / & 0.4 & - & 0.8 \\
66. & Tetradecanoic acid & 1791 & / & 1.5 & 2.3 & 0.7 \\
67. & Octadec-1-ene & 1799 & / & & 2.6 & - \\
68. & Octadecane & 1800 & 1800 & 0.2 & 1.1 & - \\
69. & Neophytadiene & 1849 & 1925 & 1.4 & 4.5 & - \\
70. & Hexahydroxfaresyl acetone (Phytone) & 1857 & 2082 & 4.0 & - & 6.6 \\
71. & Pentadecanoic acid & 1896 & / & 0.2 & - & - \\
72. & Nonadecane & 1900 & 1900 & 0.7 & 4.6 & - \\
73. & (_E,E_)-Famesyl acetone & 1928 & & 0.9 & - & 1.5 \\
74. & Methyl hexadecanoate & 1937 & / & 0.3 & - & 0.7 \\
75. & Isophytol & 1960 & / & 0.3 & - & 0.2 \\
76. & Hexadecanoic acid & 1963 & / & 5.7 & 2.2 & 6.8 \\
77. & Eicos-3-ene \({}^{*}\) & 1998 & / & - & 2.3 & - \\
78. & Eicosane & 2000 & 2000 & - & 1.5 & - \\
79. & Heneicosane & 2100 & 2100 & 2.2 & 8.7 & - \\
80. & Phytol \({}^{*}\) & 2135 & / & 1.9 & - & - \\
81. & Linoleic acid & 2165 & / & 3.9 & - & 5.3 \\
82. & Docosane & 2200 & 2200 & 0.5 & 2.6 & - \\
83. & Tricosane & 2300 & 2300 & 6.8 & 25.7 & - \\
84. & Tetracosane & 2400 & 2400 & 1.3 & 4.7 & - \\
85. & 3-Methylbutyl 3-methylbutanoate & / & 1306 & 0.2 & - & - \\
86. & \(\alpha\)-Thujone & / & 1469 & 0.3 & - & 0.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._Contrary to the oil chemical composition, the headspace contained abundant monoterpene hydrocarbons, the major ones being _p_-cymene (2.8%; 3.5%), \(\gamma\)-terpinene (2.2%; 2.2%) and limonene (1.5%; 1.8%). Several were only found in the headspace with low percentages (\(\alpha\)-pinene, sabinene, \(\beta\)-pinene, _p_-cymene, limonene, \(\gamma\)-terpinene and \(\alpha\)-terpinolene). Oxygenated monoterpenes were generally present in the headspace and essential oil (although with different abundances) and the major ones in the headspace were terpinene-4-ol (10.3%; 6.9%), mentone (6.1%; 4.3%), linalool (2.8%; 0.9%), \(\beta\)-thujone (2.8%; 1.2%), camphor (5.1%; 2.0%), isomenthone (0.9%; 1.6%), menthol (2.9%; 6.7%) and menthyl acetate (1.6%; 0.9%). Only few oxygenated monoterpenes were exclusively found in the headspace: 1,8-cineole, bornyl acetate and verbenone. \(\beta\)-Caryophyllene (3.7%; 1.6%), _trans_-\(\beta\)-farnesene (2.5%; 0.7%), \(\alpha\)-copaene (2.0%; 0.8%) and longifolene (1.0%; 1.6%) were identified among sesquiterpenes with higher percentages in comparison to the oil, but great number of other essential oil sesquiterpenes (Table 2) were not found by HS-SPME.