## 2 Results and Discussion
### Isolation of Volatile Compounds
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**No.** & **Volatile Compounds** & **RT \({}^{\text{a}}\)** & **RI \({}^{\text{b}}\)** & **Boiling Point (\({}^{\text{c}}\)C)** & **Min (mg kg\({}^{\text{-1}}\))** & **Max Max (mg kg\({}^{\text{-1}}\))** & **Average (mg kg\({}^{\text{-1}}\))** \\ \hline \multicolumn{8}{c}{**Esters**} \\ \hline
1 & methyl octanoate & 18.3 & 1123 & 190.6 & 0.00 & 2.72 & 0.46 \\
2 & methyl nonanoate & 21.3 & 1222 & 213.5 & 0.09 & 11.63 & 1.41 \\
3 & methyl decanoate & 24.3 & 1321 & 236.4 & 0.00 & 1.17 & 0.12 \\
4 & methyl hexadecanoate & 39.7 & 1929 & 373.6 & 0.00 & 0.46 & 0.07 \\ \hline \multicolumn{8}{c}{**Aldehydes**} \\ \hline
5 & furan-2-carbaldehyde & 9.8 & 822 & 139.7 & 0.20 & 4.54 & 1.90 \\
6 & benzaldehyde & 12.6 & 957 & 162.0 & 0.52 & 10.40 & 3.64 \\
7 & 2-phenylacetaldehyde & 15.6 & 1041 & 184.8 & 0.39 & 3.56 & 1.78 \\
8 & nonanal & 17.7 & 1104 & 181.0 & 0.00 & 1.45 & 0.31 \\
9 & decanal & 20.8 & 1205 & 203.9 & 0.00 & 1.41 & 0.21 \\
10 & 4-isopropylbenzaldehyde & 21.8 & 1240 & 235.1 & 0.00 & 0.20 & 0.05 \\ \hline \multicolumn{8}{c}{**Alcohols**} \\ \hline
11 & 2-phenylethan-1-ol & 17.9 & 1111 & 228.4 & 0.00 & 5.28 & 1.94 \\
12 & 5-isopropyl-2-methylphenol & 23.5 & 1299 & 267.1 & 0.00 & 0.26 & 0.06 \\ \hline \multicolumn{8}{c}{**Ketones**} \\ \hline
13 & 1-phenylbutane-2,3-dione & 20.9 & 1210 & 289.7 & 0.00 & 1.37 & 0.48 \\
2-isopropyl-5-methylcyclohexa- & 2,5-diene-1,4-dione & 22.0 & 1247 & 323.0 & 0.00 & 0.59 & 0.08 \\
14 & (thymoquinone) & 24.9 & 1343 & 327.5 & 0.00 & 3.87 & 0.93 \\
15 & (Z)-3-hydroxy-4-phenylbut-3- & 27.7 & 1427 & 332.0 & 0.00 & 0.37 & 0.09 \\ \hline \multicolumn{8}{c}{**Hydrocarbons**} \\ \hline
17 & butane & 1.6 & \textless{}800 & 18.0 & 0.00 & 20.58 & 1.03 \\
18 & heptane & 3.4 & \textless{}800 & 86.6 & 0.00 & 10.32 & 0.58 \\
19 & octane & 5.9 & 800 & 109.5 & 0.00 & 5.83 & 0.45 \\
20 & nonane & 10.3 & 896 & 132.4 & 0.00 & 1.68 & 0.20 \\
21 & undecane & 17.6 & 1100 & 178.1 & 0.04 & 34.49 & 2.33 \\ \hline \multicolumn{8}{c}{**Nitriles**} \\ \hline
22 & isobutyronitrile & 2.2 & \textless{}800 & 119.6 & 0.00 & 11.66 & 0.92 \\
23 & 2-methylbutanenitrile & 3.5 & \textless{}800 & 142.5 & 0.00 & 5.01 & 0.47 \\
24 & 3-methylbutanenitrile & 3.7 & \textless{}800 & 142.5 & 0.05 & 59.16 & 7.01 \\
25 & 2-phenylacetonitrile & 18.8 & 1136 & 215.4 & 0.25 & 5.35 & 1.93 \\ \hline \multicolumn{8}{c}{**Ternels**} \\ \hline
26 & methylbenzene & 4.7 & \textless{}800 & 113.3 & 0.00 & 3.38 & 0.34 \\
27 & 1-isopropyl-4-methylbenzene & 14.9 & 1022 & 186.5 & 0.00 & 2.62 & 0.39 \\
28 & 1-methyl-4-(prop-1-en-2-yl)benzene & 17.2 & 1088 & 183.5 & 0.00 & 1.14 & 0.17 \\ \hline \multicolumn{8}{c}{**Others**} \\ \hline
29 & 2,5-diethyltetrahydroofuran & 10.0 & 890 & 147.1 & 0.00 & 7.22 & 1.35 \\
30 & methyl 2-oxo-2-phenylacetate & 22.7 & 1271 & 271.1 & 0.00 & 0.54 & 0.18 \\
31 & 1,1,5-trimethyl-1,2-dihydronaphthalene & 25.2 & 1351 & 270.9 & 0.00 & 1.39 & 0.37 \\ \hline \multicolumn{8}{c}{**RT: Retention time (min); \({}^{\text{b}}\) RI: Experimental retention index.**} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Volatile compounds isolated from the headspace of thyme honey. Summarizing the recent literature, volatile compounds of honey are strongly related to its botanical origin and the geographical area of collection. For this reason, a major criterion before optimization was to ensure the samples are monoflorl. Our results have shown several similarities, comparing with other studies. [PERSON] et al., (16) reported 1-phenylbutane-2,3-dione, 3-hydroxy-1-phenylbutan-2-one, 3-hydroxy-4-phenylbutan-2-one, 2-phenylacetonitrile, and 5-isopropyl-2-methylphenol in 28 monoflorl honey samples from Greece. In a later study, [PERSON] et al., (27) reported 2-phenylacetaldehyde, ethyl nonanoate, benzaldehyde, and 2-phenylethan-1-ol as dominant volatile compounds in 42 monoflorl thyme honey samples from Greece.