Symbol | Independent variables | Coded level | ||||
---|---|---|---|---|---|---|
−1.68 | −1 | 0 | +1 | +1.68 | ||
A | Extraction temperature (°C) | 53.18 | 60.00 | 70.00 | 80.00 | 86.82 |
B | Extraction time (min) | 66.36 | 80.00 | 100.00 | 120.00 | 133.64 |
C | Solvent ratio (water: ethanol), v/v% | 63.18:36.82 | 70:30 | 80:20 | 90:10 | 96.82:3.18 |