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Independent variables and their levels in Box-Behnken design for flavonoids fraction of Tribulus terrestris L leaves.
| Levels | Factors |
||
|---|---|---|---|
| Ethanol concentration (X1)/(%) | Ratio of solvent to material (X2)/(ml/g) | Extraction time (X3)/(h) | |
| -1 | 10 | 20 | 20 |
| 0 | 20 | 25 | 25 |
| 1 | 30 | 30 | 30 |
