## 2 Results and Discussion
### The Headspace Chemical Composition of the Residue (HS-SPME)  
Two fibres of different polarity were used for obtaining more detailed headspace composition of the sample. Obtained chemical profiles (Table 1) are dominated by low-molecular weight and mostly volatile compounds that were probably dissolved, trapped and consequently preserved in the internal residue. These profiles are dependent on the type of used fibre: higher percentages of benzene derivatives, monoterpenes and other low-molecular weight compounds were obtained by \begin{table}
\begin{tabular}{l l c c c c} \hline
62. & 3,4-Diethyl-1,1’-biphenyl & 1751 & 0.4 & - & - \\
63. & Anthracene & 1780 & 0.1 & - & - \\
64. & 4-(1-Methyl-1-phenyl)-phenol (4- & & & & \\  & cumylphenol) & & 1814 & 0.8 & - & - \\
65. & Cembrene [** ] & 1912 & 2.0 & 0.7 & - \\
66. & 2-Methylanthracene [** ] & 1925 & 1.8 & 0.5 & 0.3 \\
67. & 1-Methyloxy-8-methylnaphthalene [** ] & 1942 & 2.2 & - & 0.3 \\
68. & Hexadecanoic acid & 1963 & - & - & 0.9 \\
69. & 7-(1-Methylethyl)-1,4a-dimethyl- & & & & \\  & 1,2,3,4,4a,9,10,10a-octahydro- & & 1988 & 9.3 & 2.7 & 2.8 \\
70. & 7-(1-Methylethyl)-1,4a-dimethyl- & & & & \\  & 2,3,4,4a,9,10-hexahpro- & & 1996 & 7.7 & 1.0 & 1.9 \\
71. & 7-(1-Methylethyl)-1,4a-dimethyl- & & & & \\  & 1,2,3,4,4a,9,10,10a-octahydro- & & 2023 & 12.2 & 3.4 & 3.6 \\  & phenanthrene & & & & \\
72. & 3,6-Dimethylphenanthrene [** ] & 2049 & 6.6 & 1.0 & 2.9 \\
73. & 1,4-Dimethoxyphenathrene [** ] & 2103 & 10.0 & 1.7 & 6.8 \\
74. & 2,3,5-Trimethylphenanthrene & 2167 & 1.2 & - & 3.2 \\
75. & 7-Ethenyl-1,2,3,4,4a,4b,5,6,7, & & & & \\  & 9,10,10a-dodecahydro-1,4a,7- & & & & \\  & trimethyl-1-phenanthrene- & & & & \\  & carboxaldehyde (pinaral) & & & & \\
76. & Methyl 8,15-pimaradien-18-oate & 2227 & 0.6 & - & 0.8 \\
77. & 1-Methyl-7-(1-methylethyl)- & & 2242 & 9.9 & 1.6 & 24.1 \\  & phenanthrene (retene) & & & & \\
78. & Methyl 8,15-isopimaradien-18-oate & 2256 & 0.5 & - & 0.6 \\
79. & 4-(2-Ethyl-5-phenyl-1H-pyrrol-3- & & & & \\  & yl)-pyridine [** ] & 2382 & 0.7 & - & 4.2 \\
80. & Methyl 6,8,11,13-abietatetraen-18- & & & & \\  & oate [** ] & 2451 & - & - & 1.7 \\
81. & Methyl dehydroabietate & 2477 & 6.0 & 1.0 & 33.6 \\ \hline \multicolumn{6}{c}{Total identified (\(\%\))} & 85.1 & 94.7 & 88.7 \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._DVB/CAR/PDMS fibre (Figure 1) in contrast to the higher percentage of naphthalene and/or phenanthrene derivatives found by using PDMS/DVB fibre (Figure 2). Significantly lower presence of high-molecular weight organic compounds in the headspace was expected, since HS-SPME is not an adequate method for their analysis. In general, monoterenes appear as predominant components in the natural pine resin, especially \(\alpha\)-pinene [5,6]. In the investigated sample of pine resin, the headspace percentage of \(\alpha\)-pinene ranged from 66.2 to 73.4% (Table 2). However, the majority of monoterenes were probably lost during heat treatment and preparation of the amphora coating due to relatively high volatility. Despite heat treatment and conditions of preservation of the ancient organic residue, several monoterenes were only found in the headspace with minor percentages such as \(\alpha\)-pinene (0.1-0.2%), camphene (0.2-0.4%), \(p\)-cymene (0.1-2.7%), limonene (0.0-0.5%), camphor (0.0-0.9%), borneol (1.1-4.5%) and bornyl acetate (0.0-0.6%). All these compounds are found in natural pine resin with considerably more headspace abundance (Table 2).