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The process parameters setting for LLPs extraction, according to Box-Benkhen design.
| Factor | Level | ||
|---|---|---|---|
| −1 | 0 | 1 | |
| X1-E/S ratio /(U/g) | 700 | 1,400 | 2,100 |
| X2-Extraction pH value | 4.0 | 5.0 | 6.0 |
| X3-ultrasound times/min | 20 | 30 | 40 |
| X4-ultrasonic temperature/ °C | 40 | 50 | 60 |
