## Results and Discussion
### Volatile Compounds of Cirsium seidens Nakai  
The chromatograms of the volatile compounds of _C. seidens_ Nakai analyzed using the four types of SPME Arrows are shown in Figure 4. Volatile compounds such as 2-Pentyfuran, 2-Ethylfuran, 1-Methylyloheptanol, 1-Penten-3-ol, 2,2,4,6,6-Pentamethylheptane, 2,3,6,7-Tetramethyloctane, 5-Ethyl-2,2,3-trimethylheptane, 3,5-Octadien-2-one, \(\beta\)-Cyclocitral, and trans-\(\beta\)-Ionone were mainly observed. Other volatile compounds such as cryophyllene, trans-\(\beta\)-Ionone (also named as 4-(2,6,6-Trimethyl-1-cyclohexen-1-yl)-3-buten-2-one), and \(\beta\)-Ionone epoxide were previously reported in the essential oils extracted from _C. seidens_ Nakai [11]. Volatile compounds belonging to the alcohol group were present in large amounts based on the peak areas (from \(327.16\times 10^{6}\) to \(2200.41\times 10^{6}\) area units) in the extractions performed from all four types of SPME Arrows. In addition, aliphatic hydrocarbons, especially 2,2,4,6,6-pentamethylheptane, were the most abundant volatile compounds extracted by all four SPME Arrows, except the PA-coated Arrow. Further, 1-Methylylcyloheptanol, 1-Penten-3-ol, and _trans_-\(\beta\)-Ionone were also present in high amounts based on the peak area in the extractions from all  
Figure 3: Reproducibility of each solid-phase microextraction Arrow as measured by comparing the relative standard deviation (RSD) (%) and standard deviation of the RSD (%) calculated using identified volatile compounds CWR/PDMS, carbon wide range/polydimethylsiloxane; DVB, divinylbenzene; PA, polyacrylate.  
Figure 2: Comparison of the sum of normalized peak areas for each class of volatile compounds extracted from _Cirsium seidens_ Nakai using four types of solid-phase microextraction Arrows. CWR/PDMS, carbon wide range/polydimethylsiloxane; DVB, divinylbenzene; PA, polyacrylate.  
four Arrows. Among those compounds, 1-Penten-3-ol is known to smell like green vegetables [28] and _trans_-\(\beta\)-ionone represents a violet-like, sweet, and floral scent [29; 30]. In particular, volatiles extracted with CWR/PDMS-coated SPME Arrows showed a particularly high amount of 2-pentylfuran, which is formed from linoleic acid and is well-known for its involvement in lipid oxidation. It is reported to smell like earthy beany vegetables and is expected to undergo changes in content upon drying and storage depending upon storage conditions, which can eventually change the flavor [31; 32]. Moreover, 3,5-Octadien-2-one, which imparts a mushroom-like flavor, was also present in high amounts [33]. \(\beta\)-Cyclocitral was present in high amounts based on the peak area in the extractions performed by all SPME Arrows except that with a PDMS coating. \(\beta\)-Cyclocitral is one of the monoterpenoids derived from carotenoids. It is an important compound, commonly found in many plants, vegetables, and fruits, has a sweet smell, and imparts a distinct fruity flavor [33]. The presence of the volatile compounds that belong to the group of terpen are consistent with previous reports by [PERSON] that demonstrated the presence of these compounds in essential oils obtained from _C. setidens_[11].  
Figure 4: Total ion chromatogram of volatile compounds from _Cirsium setidens_ Nakai extracted using solid-phase microextraction Arrows. (**a**) Carbon wide range/polydimethylsiloxane (CWR/PDMS), (**b**) divinylbenzene/PDMS (DVB/PDMS), (**c**) PDMS, and (**d**) polyacrylate (PA). The peak numbers correspond to the compounds as follows: (1) 2,2,4,6,6-Pentamethylheptane, (2) 1-Penten-3-ol, (3) 2-Pentylfuran, (4) 3,5-Octadien-2-one, (5) 1-Methylcycloheptanol, (6) \(\beta\)-Cyclocitral, and (7) trans-\(\beta\)-Ionone.