| Trial | Experimental design | Experimental set up | ||||
| X1 | X2 | X3 | Organic modifier (%) | Flow rate (mL/min) | Temperature (˚C) | |
| 1 | −1 | −1 | 0 | 80 | 0.3 | 30 |
| 2 | 1 | 0 | 1 | 90 | 0.5 | 35 |
| 3 | 0 | 0 | 0 | 85 | 0.5 | 30 |
| 4 | 1 | −1 | 1 | 90 | 0.3 | 35 |
| 5 | 0 | −1 | 1 | 85 | 0.3 | 35 |
| 6 | −1 | 1 | 1 | 80 | 0.7 | 35 |
| 7 | −1 | 1 | −1 | 80 | 0.7 | 25 |
| 8 | 1 | −1 | 0 | 90 | 0.3 | 30 |
| 9 | 0 | 0 | 0 | 85 | 0.5 | 30 |
| 10 | 0 | 0 | 0 | 85 | 0.5 | 30 |
| 11 | −1 | −1 | −1 | 80 | 0.3 | 25 |
| 12 | 1 | 1 | −1 | 90 | 0.7 | 25 |
| 13 | −1 | 1 | 0 | 80 | 0.7 | 30 |
| 14 | −1 | 0 | 1 | 80 | 0.5 | 35 |
| 15 | 1 | 0 | −1 | 90 | 0.5 | 25 |
| 16 | 0 | 0 | −1 | 85 | 0.5 | 25 |
| 17 | 0 | 0 | 1 | 85 | 0.5 | 35 |
| 18 | 0 | −1 | 1 | 85 | 0.3 | 35 |
| 19 | 0 | −1 | −1 | 85 | 0.3 | 25 |
| 20 | 0 | 1 | 1 | 85 | 0.7 | 35 |
| 21 | −1 | 0 | 0 | 80 | 0.5 | 30 |
| 22 | 1 | 0 | 0 | 90 | 0.5 | 30 |
| 23 | 1 | 1 | 1 | 90 | 0.7 | 35 |
| 24 | 0 | −1 | 0 | 85 | 0.3 | 30 |
| 25 | 1 | −1 | −1 | 90 | 0.3 | 25 |
| 26 | 0 | 1 | 0 | 80 | 0.7 | 30 |
| 27 | −1 | −1 | 1 | 85 | 0.3 | 35 |
| 28 | 1 | 1 | 0 | 90 | 0.7 | 30 |
| 29 | −1 | 0 | −1 | 80 | 0.5 | 25 |