# GC-MS Analysis of the Volatile Constituents in the Leaves of 14 Composite Plants
## 2 Results  
### Identification and Quantification of the Chemical Constituents in 14 Compositae Plants  
According to GC-MS analysis, 213 constituents were detected and tentatively identified in the n-hexane extracts of 14 samples (Figure 1 and Table S1). The components were classified into nine categories, including four groups of terpenoids (monoterpenes, sesquiterpenes, diterpenes, and oxygenated terpenoids), aromatic compounds, fluorinated compounds, alkanes, alkanols, and others (components such as ketones, enols, and esters, which are not terpenoids). The terpenoidsaccounted for 117 components and included 12 monoterpenes; 26 sesquiterpenes; one diterpene; and 78 oxygenated terpenoids, consisting of 38 oxygenated monoterpenes or their derivatives, 34 oxygenated sesquiterpenes, four oxygenated diterpenes, and two oxygenated triterpenes. Different quantities of the constituents existed among the tested species (Table 1). The numbers of total components ranged from 11 to 55, with the fewest constituents detected in the leaves of _A. japonica_ (**S5**) and _Artemisia sericea_ (**S7**) and the most detected in _A. yunnanensis_ (**S4**) and _O. taihangensis_ (**S14**). The terpenoids in _A. yunnanensis_ (**S4**), _O. taihangensis_ (**S14**) and _Artemisia abrotanum_ (**S6**) were also the most abundant. Ethyl decanoate solutions with known concentrations were used for the semi-quantitative analysis of each volatile component and the total compounds (Table S1). The concentrations of oxygenated \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Categories**} & \multicolumn{10}{c}{**Number of Volatile Categories**} \\ \cline{2-13}  & **S1 b** & **S2** & **S3** & **S4** & **S5** & **S6** & **S7** & **S8** & **S9** & **S10** & **S11** & **S12** & **S13** & **S14** \\ \hline MT & 2 & 3 & 2 & 3 & 2 & 1 & 0 & 1 & 2 & 0 & 4 & 0 & 1 & 3 \\ ST & 9 & 2 & 4 & 13 & 4 & 3 & 0 & 7 & 4 & 5 & 8 & 3 & 2 & 8 \\ DT & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ OT & 6 & 7 & 3 & 17 & 1 & 20 & 4 & 12 & 7 & 3 & 7 & 5 & 6 & 20 \\ AC & 1 & 3 & 0 & 3 & 0 & 1 & 0 & 1 & 2 & 1 & 1 & 3 & 0 & 1 \\ FC & 0 & 1 & 0 & 0 & 1 & 1 & 0 & 2 & 1 & 0 & 0 & 2 & 1 & 1 \\ Alkanes & 4 & 2 & 3 & 3 & 1 & 2 & 1 & 0 & 5 & 1 & 2 & 1 & 1 & 0 \\ Alkanols & 2 & 0 & 3 & 4 & 1 & 2 & 2 & 4 & 2 & 2 & 2 & 1 & 2 \\ Others & 2 & 2 & 6 & 12 & 1 & 7 & 4 & 8 & 11 & 4 & 4 & 6 & 5 & 5 \\ TC & 26 & 21 & 21 & 55 & 11 & 37 & 11 & 35 & 34 & 16 & 28 & 22 & 17 & 40 \\ \hline \hline \end{tabular}  
* MT, monoterpenes; ST, sesquiterpenes; DT, diterpenes; OT, oxygenated terpenes; AC, aromatic compounds; FC, fluorinated compounds; TC, total compounds; b Sample numbers are the same as in Table 2.  
\end{table} 
Table 1: Number of volatile categories from leaves of 14 samples. Figure 1: Total ion chromatogram of volatile components in some species of tested plants. terpenoids and total compounds varied widely among these species (Figure 2), with a range of 8.20 to 3493.38 ng/g fresh weight (FW) for the former and 275.27 to 5931.41 ng/g FW for the latter. The concentrations of oxygenated terpenoids and total compounds were the lowest in _A. japonica_ (**S5**), and its total terpenoid content (170.22 ng/g FW) was also much lower than those of other species. By contrast, _A. yunnanensis_ (**S4**) contained the highest levels of sesquiterpenes (900.17 ng/g FW), oxygenated terpen and total terpenoids. The most abundant monoterpenes (354.10 ng/g FW) were found in the leaves of _A. absinthium_ (**S2**). In addition, the leaves of some species such as _A. abrotanum_ (**S6**), _A. argyi_ (**S8**), _C. indicium_ var. _aromatic_ (**S10**), and _O. taihangensis_ (**S14**) also contained high total volatile contents that exceeded 1500 ng/g FW. Relatively high levels of total terpenoids, of which concentrations exceeded 1000 ng/g FW, were also detected in these four species. However, the total terpenoid and total compound contents in the leaves of _C. indicium_ (**S11**) and _O.