## 3 Results and Discussion  
### Optimization of the Device by Using OAD  
Figure 1 shows a diagram of the homemade extraction device developed in this study. It was a 2-L recycled PET plastic bottle used as a chamber to facilitate the extraction of volatile components from a live water lily, which was still cultured in a water basin. The apparatus consisted of a chamber and thumbtacks to secure a microfan, and the HS-SPME part was inserted between the microfan and the live water lily (Figure 1). The proper configuration was determined by using OAD to optimize the design to improve extraction efficiency. The configuration parameters included the angle and position of the fiber to the fan (A), the direction of air movement (B), and the distance from the fan to the sample (C). All the tested parameters and levels (high or low) are shown in Tables 1 and 2. In Table 1, for the position of the fiber to the fan (A), the angle of the fiber to the fan was vertical or parallel, which referred to the setting level. For the direction of air movement (B), the airstream making positive or negative pressure was the level. For the distance from the fan to the sample (C), the distance of the fan from the flower was set as low/high, which referred to near/far, respectively. Further, the position of the fiber to the fan (A) displayed in Table 2, which is the same variable listed in Table 1, was modified as the location of the fiber to the fan and was set as up/down, referring to close to/far from the fan, respectively. The fiber could not be placed at a vertical angle between the fan and the sample; thus, the angle effect is first discussed (Table 1). Because of the composition variation between flowers and flowering time, the peak area of the model compound, instead of the real sample, was used for evaluation. Due to the different constituents of volatile components of flowers caused by different plants and blossom seasons, a statistical method was required to objectively evaluate these differences. Eight experiments (runs) were performed according to the OAD method, and all of the average responses were in triplicate. From the direct analysis of the data from part 1, we can observe that the parameter effect order was B > C > A > B*C > A*B > A*C, and the results demonstrated that the A\({}_{1}\)B\({}_{1}\)C\({}_{-1}\) group was the best assembly for this extract cell. This means that the effect of air movement direction on extraction efficacy was greater than others, and the interactions among the parameters were smaller than others. Moreover, when the angle of the fiber was parallel to the fan, the air movement direction produced positive pressure for the sample, and the distance from the fan was closer to the sample. To verify whether the effect of the variables on extraction efficiency was statistically significant, ANOVA was used to interpret the experimental data obtained from OAD optimization. Based on the ANOVA results, when \(p<0.05\), the variables were statistically significant. ANOVA showed that the effects of parameters of A, B, and C on the results were significant but independent of each other. The resulting equation is as follows: Y = 1858092 + 767975X\({}_{\mathrm{A}}\) + 1120733X\({}_{\mathrm{B}}\) - 429035X\({}_{\mathrm{AB}}\) - 601766X\({}_{\mathrm{C}}\) - 383569X\({}_{\mathrm{AC}}\) + 495404X\({}_{\mathrm{BC}}\). In this equation, the coefficients of parameters A and B were positive, and C was negative. The result was the same as the direct analysis: the configuration of A\({}_{1}\)B\({}_{1}\)C\({}_{-1}\) was the best. To determine the effect of fiber position, the OAD L\({}_{8}\) (\(2^{7}\)) matrix was used. In Table 2, the variable A was replaced as the position of the fiber to the fan, while the others remain the same. The results indicated that the two-variable interaction A \(\times\) B had the highest range (\(k_{max}\)-\(k\)) value of 4,863,596 and exerted the largest effect on extraction efficiency (Table 2).