# Comparison and Identification of the Aroma-Active Compounds in the Root of _Angelica dahurica_
## 2 Results and Discussion
### Key Aroma-Active Compounds Identified by SPME-AEDA
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**No**} & \multirow{2}{*}{**Compound**} & \multirow{2}{*}{**CAS**} & \multicolumn{2}{c}{**RI**} & \multirow{2}{*}{**Odor**} & \multicolumn{2}{c}{**FD**} \\ \cline{5-9}  & & & **DB-Wax** & & **DB-5** & & **Hangbaizhi** & **Qibaizhi** & **Bobaizhi** \\ \hline
1 & 2-Methyl-2-butenal & 1115-11-3 & 1101 & 753 & green, fruity & 1 & 1 & 9 \\ \hline
2 & \(\beta\)-Pinene & 127-91-3 & 1116 & 981 &
\begin{tabular}{c} pine, resin, \\ turpentine \\ \end{tabular} & 9 & 27 & 9 \\ \hline
3 &
\begin{tabular}{c} Prenol \\ \end{tabular} & 556-82-1 & 1127 & 779 & herb & 81 & 81 & 81 \\ \hline
4 & \
\begin{tabular}{c} Heptanal \\ \end{tabular} & 111-71-7 & 1174 & 903 &
\begin{tabular}{c} fatty, citrus, \\ racid \\ \end{tabular} & 1 & 1 & 1 \\ \hline
5 &
\begin{tabular}{c} trans-\(\beta\)-Ocimene \\ \end{tabular} & 3779-61-1 & 1242 & 1038 & sweetie, herb & - & 1 & 1 \\ \hline
6 & \
\begin{tabular}{c} Octanal \\ \end{tabular} & 124-13-0 & 1280 & 1006 &
\begin{tabular}{c} fatty, soap, \\ lemon \\ \end{tabular} & 1 & 1 & 1 \\ \hline
7 & 6-Methyl-5-hepten-2-one & 110-93-0 & 1336 & 974 & mushroom & 1 & 1 & 1 \\ \hline
8 &
\begin{tabular}{c} Nonanal \\ \end{tabular} & 124-19-6 & 1385 & 1104 & citrusy, green & 27 & 1 & 27 \\ \hline
9 & \
\begin{tabular}{c} Acetic acid \\ \end{tabular} & 64-19-7 & 1450 &
\begin{tabular}{c} sour \\ \end{tabular} & 9 & 9 & 9 \\ \hline
10 & \(\alpha\)-Copane & 3856-25-5 & 1488 &
\begin{tabular}{c} woody, spice \\ \end{tabular} & 27 & 3 & 27 \\ \hline
11 &
\begin{tabular}{c} Caryophyllene \\ \end{tabular} & 87-44-5 & 1594 & 1467 & woody, spice & 3 & 9 & 1 \\ \hline
12 & \((-)\)-\(\beta\)-Elemene & 515-13-9 & 1595 & 1398 & spice & 1 & 81 & 1 \\ \hline
13 &
\begin{tabular}{c} Aromadendrene & 489-39-4 & 1600 & 1475 & woody & - & - & 9 \\ \hline
14 & \(\gamma\)-Elemene & 29873-99-2 & 1636 & 1425 &
\begin{tabular}{c} green, \\ woody, oil \\ \end{tabular} & - & 1 & - \\ \hline
15 &
\begin{tabular}{c} Humulene \\ \end{tabular} & 6753-98-6 & 1663 & 1467 & woody & - & 9 & - \\ \hline
16 & \(\gamma\)-Muurolene & 30021-74-0 & 1681 & 1475 &
\begin{tabular}{c} herb, woody, \\ spice \\ \end{tabular} & - & 27 & - \\ \hline
17 & \(\alpha\)-Gurjunene & 489-40-7 & 1760 &
\begin{tabular}{c} woody \\ \end{tabular} & - & - & 81 \\ \hline
18 & \
\begin{tabular}{c} Caryophyllene oxide \\ \end{tabular} & 1139-30-6 & 1962 &
\begin{tabular}{c} herb, \\ sweetie, \\ spice \\ \end{tabular} & 3 & 3 & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Dilution analysis of _A. dahurica_ using SPME combined with AEDA. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**No**} & \multirow{2}{*}{**Compound**} & \multirow{2}{*}{**Y**} & \multirow{2}{*}{**R2**} & \multicolumn{2}{c}{**Hangbaizhi**} & \multicolumn{2}{c}{**Qibaizhi**} & \multicolumn{2}{c}{**Bobaizhi**} \\ \cline{5-9}  & & & \multicolumn{2}{c}{**Concentration**} & \multirow{2}{*}{**FD**} & \multicolumn{2}{c}{**Concentration**} & \multirow{2}{*}{**FD**} & \multicolumn{2}{c}{**Concentration**} & \multirow{2}{*}{**FD**} & \multirow{2}{*}{**FD**} \\ \cline{5-9}  & & & \multicolumn{2}{c}{**(ng/g)**} & & & & **(ng/g)** & & **(ng/g)** & **FD** \\ \hline
1 & 2-Methyl-2-butenal & \begin{tabular}{c} y = 11,238x \\ + 468,104 \\ \end{tabular}  & 0.9981 & \begin{tabular}{c} 124.13 \(\pm\) 9.19 \({}^{\rm a}\) \\ \end{tabular}  & 1 & \ \begin{tabular}{c} 179.65 \(\pm\) 10.26 \({}^{\rm b}\) \\ \end{tabular}  & 1 & \begin{tabular}{c} 304.83 \(\pm\) 15.53 \({}^{\rm c}\) \\ \end{tabular}  & 9 \\
2 & \(\beta\)-Pinene & \begin{tabular}{c} y = 8207.2x \\ + 15,568 \\ \end{tabular}  & 0.9904 & \begin{tabular}{c} 20.63 \(\pm\) 1.29 \({}^{\rm a}\) \\ \end{tabular}  & 9 & \ \begin{tabular}{c} 26.59 \(\pm\) 0.48 \({}^{\rm b}\) \\ \end{tabular}  & 27 & \begin{tabular}{c} 21.37 \(\pm\) 2.60 \({}^{\rm a}\) \\ \end{tabular}  & 9 \\
3 & \begin{tabular}{c} Heptanal \\ \end{tabular}  & \begin{tabular}{c} y = 2918.3x \\ - 29,754 \\ \end{tabular}  & 0.9969 &