# Analysis of Floral Fragrance Components in Different Parts of _Iris typhifolia_
## 2 Materials and Methods
### Research Methodology
#### 2.2.3 Identification and Analysis Methods  
Qualitative method: Each individual component was retrieved and compared against the NIST 2017 mass spectrometry and standard information database, and their identifi  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Array Serial No.** & **Sensor Name** & **Performance Description** \\ \hline
1 & W1C & aromatic \\
2 & W5S & broad range \\
3 & W3C & aromatic \\
4 & W6S & hydrogen \\
5 & W5C & arom–aliph \\
6 & W1S & broad–methane \\
7 & W1W & sulphur–organic \\
8 & W2S & broad–alcohol \\
9 & W2W & sulphur–chlor \\
10 & W3S & methane–aliph \\ \hline \hline \end{tabular}
\end{table}
Table 1: Response characteristics of each sensor of PEN3 electronic nose.  
cation was cross-verified with the relevant literature. They were identified and analyzed together using the related literature. By using the carbon standard method and the same column as well as rising and cooling procedure as GC-MS, the mixed standard of C7-C30 normal alkane was used as the standard to calculate the linear retention index (Formula (1)) of various aroma components of _Iris typhifolia_ samples. The results were compared with those of NIST spectrum database. Starting from the first stable peak according to the ion peak diagram, the stable peak corresponds to the first place of a variety of substances under the same RT value, and the selected substances should appear under the same RT value in the three basic biological repeats and rank in the top three.  
\[\text{LRI}=100\ \text{z}+100\ (\text{RT}-\text{RT}_{\text{z}})/(\text{RT}_{ \text{(z}+\text{n)}}-\text{RT}_{\text{z}}) \tag{1}\]  
Quantitative method: Internal standard substance method. First, 2-nonone was selected as the internal standard material, and the density was 0.82 g/mL. The volume of the internal standard substance (\(\mu\)L) added was 10 times the sample mass (g) in numerical terms. All kinds of aroma components in the _Iris typhifolia_ sample were quantized, (Formula (2)), and the average value was obtained after three biological repeats.  
\[\text{Mi}=\text{C}_{0}\times\text{V}_{0}\times\text{A}_{\text{i}}\div(\text{A} _{0}\times\text{M}) \tag{2}\]  
In Formula (2), Mi is the content of each aroma component (\(\mu\)g/g), and C\({}_{0}\) is the internal standard substance concentration (\(\mu\)g/\(\mu\)L), while V\({}_{0}\) is the internal standard substance volume (\(\mu\)L). A\({}_{\text{i}}\) is the peak area of the desired aroma component, A\({}_{0}\) is the internal standard substance peak area, and M is the sample mass (g).  
OAV value: the ratio of the mass concentration of the substance (Formula (3)) to the threshold value of the substance in water (Formula (4)) is regarded as a standard to evaluate the contribution of the substance to the overall aroma profile of the sample, thus selecting out the standard sample for aroma reconstruction from it, in which the substance with OAV \(\geq\) 1 is the characteristic aroma component [13].  
\[\text{C}_{\text{i}}=\text{C}_{0}\times\text{A}_{\text{i}}\div\text{A}_{0} \tag{3}\]  
In Formula (3), C\({}_{\text{i}}\) is the mass concentration of each aroma component (\(\mu\)g/mL), and C\({}_{0}\) is the internal standard substance concentration (\(\mu\)g/\(\mu\)L). A\({}_{\text{i}}\) and A\({}_{0}\) are the peak area and internal standard substance peak area of the aroma component, respectively.  
\[\text{OAV}=\text{C}_{\text{i}}\div\text{OT}_{\text{i}} \tag{4}\]  
In Formula (4), OT\({}_{\text{i}}\) is the threshold value of the aroma component in water (\(\mu\)g/mL) [14]. If there is no numerical value for the threshold of a compound in water, then the value of the closest medium by properties to water should be selected.