## 2 Results and Discussion
### Organic Volatiles Isolated by USE  
During the course of our well established methodology of ultrasonic assisted honey extraction using different solvents [16] we performed USE separately applying two solvents: solvent A - mixture of pentane and diethyl ether (1:2 v/v) and solvent B - dichloromethane. Identified compounds in both extracts are listed in Table 2. The C\({}_{13}\)-norisoprenoid vomifoli was the most abundant single compound, with ranges of 10.7%-13.8% (solvent A) and 21.6%-24.2% (solvent B). It was not found in the headspace, probably due to its polarity and less volatility, as we already reported in our previous screening on _Mentha_ spp. L. honey volatiles [17]. In distinction from the headspace composition, only 4-ketoisophorone (0.2%-1.9%; 0.1%-0.6%) and 4-hydroxy-\(\alpha\)-isophorone (0.3%-0.6%; 0.0%-0.1%) were found among C\({}_{\beta}\)-norisoprenoids. Methyl syringae was the second abundant compound (4.5%-6.8%; 3.8%-4.2%). Aromatic acids and esters (Table 2) were the most widespread in solvent A and solvent B extracts respectively: benzoic acid (2.5%-4.9%; 0.3%-0.8%), phenylacetic acid (0.8%-1.4%; 0.1%-0.2%), vanillin (0.0%-0.5%; 0.0%-0.2%), 4-methoxybenzoic acid (0.4%-4.7%; \begin{table}
\begin{tabular}{c l c c c c} \hline
20. & Lilac aldehyde (isomer III) & 1174 & 2.2 & 4.9 & 3.37 & 1.39 \\
21. & 3,5,5-Trimethylcyclohexan- & 1177 & 0.0 & 1.8 & 0.93 & 0.90 \\
22. & Benzoic acid & 1181 & 0.2 & 1.4 & 0.87 & 0.61 \\
23. & Safranal & 1206 & 0.0 & 1.0 & 0.40 & 0.53 \\
24. & Lilac alcohol (isomer I) & 1210 & 0.1 & 1.1 & 0.47 & 0.55 \\
25. & Lilac alcohol (isomer II) & 1220 & 0.0 & 0.6 & 0.27 & 0.31 \\
26. & Lilac alcohol (isomer III) & 1222 & 0.1 & 0.6 & 0.30 & 0.26 \\
27. & Car-2-en-4-one * & 1228 & 0.0 & 1.2 & 0.67 & 0.61 \\  & 2-Hydroxy-3,5,5-trimethyl- & & & & & \\
28. & cyclohex-2-en-1,4-dione & 1245 & 0.0 & 0.6 & 0.30 & 0.30 \\  & (2-Hydroxy-4- & & & & & \\ ketoisophorone) & & & & & & \\
29. & 5-Hydroymethylfurfurral & 1254 & 0.7 & 1.8 & 1.17 & 0.57 \\
30. & 4-Methoxybenzaldehyde & & 1264 & 1.4 & 10.9 & 4.93 & 5.20 \\  & (4-Anisaldehyde) & & & & & \\
31. & 1-Methoxy-4-propylbenzene & 1307 & 0.5 & 5.3 & 2.60 & 2.46 \\
32. & 3,4,5-Trimethylphenol** & 1336 & 1.1 & 3.6 & 2.40 & 1.25 \\
33. & Coumarin & 1444 & 0.9 & 1.8 & 1.23 & 0.49 \\
34. & Hexadecanoic acid & 1981 & 0.5 & 3.0 & 1.50 & 1.32 \\ \hline \end{tabular}
\begin{tabular}{c l c c c c} \hline RI = retention indices on HP-5 MS column; A = solvent-free HS-SPME; * - tentatively identified; ** - correct isomer not identified. \\ \end{tabular}
\end{table} 
Table 1: _Cont._0.2%-1.8%), methyl 4-hydroxybenzoate (0.0%-0.5%; 0.0%-0.2%), methyl vanillin (0.0%-0.9%; -), methyl 4-hydroxy-3-methoxybenzoate (0.9%-2.9%; 0.1%-0.5%), methyl 4-methoxy-benzoate (2.0%-3.3%; 0.3%-1.0%), methyl 2,5-dihydroxybenzoate (0.0%-1.0%; 0.0%-0.3%), 4-hydroxybenzoic acid (0.4%-3.7%; -), 3,4-dimethoxybenzoic acid (-; 0.3%-1.0%). Other present phenyl-propane aldehydes and alcohols were: benzaldehyde (0.0%-0.3%; 0.0%-0.2%), benzyl alcohol (0.0%-0.2%; 0.0%-0.1%), phenylacetaldehyde (0.0%-0.4%; 0.0%-0.1%), 4-methoxybenzaldehyde (1.0%-1.9%; 0.1%-0.3%), 4-methoxybenzyl alcohol (0.0%-0.3%; -), 4-methoxy-2-phenylethanol (0.3%-0.5%; 0.0%-0.1%), 4-hydroxybenzaldehyde (0.0%-0.3%; 0.0%-0.1%). Coumarin was found with higher percentages in solvent A (1.1%-2.4%) in comparison with solvent B (0.3%-0.4%).