Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Coded and uncoded levels of independent variables used in the RSM design.
| Levels of coded variables | Independent variables | |||
|---|---|---|---|---|
| Ethanol concentration, % (X1) |
Temperature, °C (X2) |
Sample-to-solvent ratio, w/v (X3) |
Extraction time, h (X4) |
|
| −1 | 30 | 60 | 1 : 10 | 2 |
| 0 | 50 | 70 | 1 : 20 | 3 |
| 1 | 70 | 80 | 1 : 30 | 4 |
