Table 4.
Analytical conditions of the HPLC system for determining rhein.
| Parameters | Chromatographic Conditions | ||
|---|---|---|---|
| A | B | C | |
| Column | Luna Omega Polar C18 column (5 μm, 100 Å, 4.6 mm × 250 mm) (Phenomenex Inc., Torrance, CA, USA) |
||
| Column temperature | 25 °C | 30 °C | 30 °C |
| Flow rate | 1 mL/min | 0.8 mL/min | 1 mL/min |
| Injection volume | 10 μL | 10 μL | 10 μL |
| Detection wavelength | 254 nm | 254 nm | 254 nm |
| Mobile phase | Methanol: 2% v/v aqueous acetic acid (70:30) |
Acetonitrile: 0.5% v/v aqueous acetic acid (60:40) |
Acetonitrile: 0.1% v/v aqueous phosphoric acid (65:35) |
| Run time | 20 min | 15 min | 15 min |
| Resolution | 10.79 | 0.88 | 6.80 |
| Symmetry factor | 0.85 | 1.20 | 0.85 |
| Theoretical plate | 17,520 | 3315 | 8968 |
| Retention time (min) | 16.683 | 9.459 | 6.195 |
| Purity factor | 238.174 | 893.232 | 996.654 |