## 3 Results
### Characterization of Non-Polar Compounds in Different Ecotypes of Burdock Roots by GC-MS
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**ID** & \begin{tabular}{c} **Proposed** \\ **Compound** \\ \end{tabular} & \begin{tabular}{c} **Rt** \\ **(min)** \\ \end{tabular} & \begin{tabular}{c} **Molecular** \\ **Formula** \\ \end{tabular} & \
\begin{tabular}{c} **Measured** \\ **Mass** \\ \end{tabular} &
\begin{tabular}{c} **Main Fragments Ions (\(m/z\))** \\ \end{tabular} & **SPLE** & **OLE** & **SPME** \\ \hline
1 &
\begin{tabular}{c} 4-Methylcatenoic \\ acid \\ \end{tabular} & 7.468 & C\({}_{9}\)H\({}_{18}\)O\({}_{2}\) & 158 & 129, 101, 99, 83, 73, 60, 57, 55, 45, 43, 41 & 359 \(\pm\) 13 & 384 \(\pm\) 26 & 401 \(\pm\) 16 \\ \hline
2 & 2-Methylphenol & 7.502 & C\({}_{7}\)H\({}_{8}\)O & 108 & 108, 107, 90, 89, 79, 77, 63, 53, 51, 44 & 740 \(\pm\) 21 & 863 \(\pm\) 40 & 609 \(\pm\) 67 \\ \hline
3 & Oleic acid & 7.758 & C\({}_{18}\)H\({}_{4}\)O\({}_{2}\) & 282 & 137, 125, 111, 101, 99, 89, 83, 81, 73, 69, & 33 \(\pm\) 51 & 390 \(\pm\) 14 & 113 \(\pm\) 17 \\ \hline
4 & Palmitic acid & 13.706 & C\({}_{16}\)H\({}_{32}\)O\({}_{2}\) & 256 & 256, 213, 129, 97, 87, 85, 83, 73, 71, 69, & 675 \(\pm\) 73 & 609 \(\pm\) 34 & 746 \(\pm\) 11 \\ \hline
5 & Methyl & 1267 & C\({}_{18}\)H\({}_{34}\)O\({}_{2}\) & 294 & 149, 135, 109, 95, 82, 81, 79, 69, 67, 55, & 298 \(\pm\) 278 & 1371 \(\pm\) 47 & 1645 \(\pm\) 26 \\ \hline
6 & Linolenic acid & 18.454 & C\({}_{18}\)H\({}_{30}\)O\({}_{2}\) & 278 & 278, 149, 108, 95, 93, 79, 67, 55, 41 & 748 \(\pm\) 80 & 579 \(\pm\) 5 & 677 \(\pm\) 37 \\ \hline
7 & Oleic acid amide & 27.121 & C\({}_{18}\)H\({}_{35}\)NO & 281 & 114, 100, 86, 72, 69, 67, 60, 59, 55, 44, & 2749 \(\pm\) 140 & - & - \\ \hline
8 & Hotrienol & 31.878 & C\({}_{10}\)H\({}_{6}\)O & 152 & 119, 105, 91, 82, 79, 71, 67, 55, 51, 43, 41 & 1076 \(\pm\) 31 & - & - \\ \hline
9 & Nerolidol & 44.181 & C\({}_{15}\)H\({}_{26}\)O & 222 & 207, 161, 136, 119, 107, 97, 93, 81, 79, & 294 \(\pm\) 1 & 258 \(\pm\) 26 & 124 \(\pm\) 19 \\ \hline
10 & \(\beta\)-stigmasterrol & 44.609 & C\({}_{29}\)H\({}_{48}\)O & 412 & 412, 351, 300, 255, 193, 119, 105, & 1884 \(\pm\) 163 & 1919 \(\pm\) 40 & 867 \(\pm\) 9 \\ \hline
11 & \(\gamma\)-sitosterol & 45.419 & C\({}_{29}\)H\({}_{50}\)O & 414 & 159, 147, 145, 133, 131, 121, 118, 107, & 4093 \(\pm\) 367 & 3321 \(\pm\) 4 & 1623 \(\pm\) 161 \\ \hline
12 &
\begin{tabular}{c} Caryophyllene \\ oxide \\ \end{tabular} & 48.163 & C\({}_{15}\)H\({}_{24}\)O & 220 & 177, 161, 147, 133, 121, 109, 96, 93, 81, & 79, 69, 67, 55, 53, 43, & 271 \(\pm\) 13 & 97 \(\pm\) 1 & 375 \(\pm\) 23 \\ \hline
13 & Spathulenol & 49.576 & C\({}_{15}\)H\({}_{26}\)O & 222 & 222, 207, 189, 133, 121, 109, 107, 95, 81, & 79, 69, 67, 55, 43 & 162 \(\pm\) 3 & 115 \(\pm\) 78 & 205 \(\pm\) 3 \\ \hline
14 & Bisnorallochanic acid & 49.767 & C\({}_{22}\)H\({}_{90}\)O\({}_{2}\) & 332 & 217, 215, 161, 149, 147, 135, 133, 124, & & & \\ \hline \multicolumn{7}{c}{Peak area expressed as \(\times 10^{3}\); (\(\cdot\)): Non-detected.} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Compounds identified by GC-MS with their respective peak areas in SPLE, OLE, and SPME burdock root extracts obtained by PLE at 100 \({}^{\circ}\)C.  
In addition to this sterol, the OLE extract was the richest extract in oleic acid (number 3) and the only phenolic compound identified by GC-MS in all the ecotypes, which corresponded to 2-methyl phenol. This compound was detected with a molecular ion at \(m/z\) 108 and fragment ions at 107 [M-H], 90 [M-CH\({}_{3}\)], 70 [M-C\({}_{6}\)H\({}_{2}\)], 77 [M-C\({}_{6}\)H\({}_{5}\)], 63, 53, and 51, involving the breakdown of the aromatic structure, phenol or methyl groups. In general, a negative influence of weeding in the OLE extracts was exhibited, with a decrease in fatty acids and terpenoids peak areas concerning the SPLE extracts collected at the same altitude but without being subjected to weeding treatment. In fact, the SPLE extracts presented higher peak areas of methyl linoleicidate and linoleic acid, in addition to the presence of oleic acid amide that was not observed in the OLE extract.