## 2 Results and Discussion
### Comparison of GC/SAW and HS-SPME-GC-MS method for H. cordata Thunb
In my previous paper, it was reported that the ability for classification among species of completely different chemotypes by HS-SPME-GC-MS is good enough, but the classification of same chemotypes species which are from different geographical origin in same country, original species and its variety, an air-drying term for 13 days and 16 months appear much lower than GC/SAW [23]. \begin{table}
\begin{tabular}{l l l l l l l l l l l l l l l l l l} \hline \hline \multirow{2}{*}{**Task**} & \multirow{2}{*}{**Compound**} & \multicolumn{8}{c}{**Length**} & \multicolumn{8}{c}{**Length**} & \multicolumn{8}{c}{**Length**} & \multicolumn{8}{c}{**Length**} & \multicolumn{8}{c}{**Length**} & \multicolumn{8}{c}{**Length**} \\ \cline{3-14}  & & \multicolumn{4}{c}{**A**} & **  
Discrimination and Quality Control of H. cordata Thunb by GC/SAW and Principal Component Analysis for GC/SAW Responses  
GC/SAW allows pattern recognition by a visual fragrance pattern, called a VaporPrint or chromatographic fingerprint derived from the frequency of a SAW sensor [22; 23; 24; 25]. Chromatographic fingerprint technique has been internationally accepted as a useful means for the quality control [28; 29]. This image is created by transforming the time variable to a radial angle with the beginning and end of the analysis [22; 23; 24; 25]. Figure 2A-C show the fragrance patterns of leaves, aerial stems, and underground stems for _H. cordata_ Thunb which are from Anmyeon Island, South Korea. As shown in Figure 2A-C, each part of plant has own characteristic fragrance pattern owing to its individual chemical compositions. Moreover, its individual characteristic fragrance patterns are conducive to discrimination of the three different parts of plant such as leaves, aerial stems, and underground stems. Table 2 shows their relative proportions (% total amounts) for leaves, aerial stems, and underground stems of _H. cordata_ Thunb which are from five different geographical origins in South Korea. To classify leaves, aerial stems, and underground stems, GC/SAW data profiles of 15 samples (Table 2) for _H. cordata_ Thunb were analyzed by PCA. To display the points in two principal components, PC 1 and PC 2 (first and second principal components) were chosen to represent the information. Figure 3 shows a principal component projection plot of PC 1 and PC 2 of leaves, aerial stems, and underground stems for _H. cordata_ Thunb (Ulreung Island, Anmyeon Island, Jeju Island, Hampyeong, and Haenam, South Korea). PC 1 and PC 2 reflected 96% of the total variance. As a result, a good classification among leaves, aerial stems, and underground stems for _H. cordata_ Thunb was obtained. These results show that the three different parts of plant such as leaves, aerial stems, and underground stems can be discriminated easily using GC/SAW, as shown in Figure 3.  
In my previous papers, it was reported that fast GC/SAW is an effective tool for species identifications and quality control [23; 24; 25]. Figure 2: Comparison of fragrance patterns for leaves (**A**), aerial stems (**B**), and underground stems (**C**) of _Houttuynia cordata_ Thunb (Anmyeon Island, South Korea) by fast GC/SAW.