Table 2.
Qualitative methods for flavones in POD.
| No. | Test methods | Qualitative features |
|---|---|---|
| 1 | Ultraviolet absorption diagram | Weak spectral Ⅰ between 300 and 400 nm; strong spectral Ⅱ between 260 and 300 nm; spectral Ⅰ is acromion of spectral Ⅱ. |
| 2 | AlCl3 reaction/AlCl3 + HCl reaction | When heated or placed for a long time, the solution is green, the ultraviolet fluorescence is enhanced and the absorption band is red-shifted. When hydrochloric acid is added, the absorption band is blue-shifted. |
| 3 | FeCl3 reaction | Solution turns green with black precipitation. |
| 4 | HCl-Mg reaction | Produce brown foam or solution turns light brown. |
| 5 | Strong alkali reaction | Solution yellow deepened or turned brown. |