Table 3 The levels of five independent variables employed in CCD. Coded factors are described in parentheses
Level | ||||||
|---|---|---|---|---|---|---|
Factor | Symbol | -α* | Lower | Center Point | Higher | + α* |
L-tyrosine (mmol.L−1) | X1 | 0.02 (− 2.38) | 1.4 (− 1) | 2.4 (0) | 3.4 (+ 1) | 4.78 (+ 2.38) |
Glucose (% v/v) | X2 | 0.11 (− 2.38) | 0.8 (− 1) | 1.3 (0) | 1.8 (+ 1) | 2.49 (+ 2.38) |
Glutamic acid (mmol.L−1) | X3 | 0.74 (− 2.38) | 3.5 (− 1) | 5.5 (0) | 7.5 (+ 1) | 10.26 (+ 2.38) |
L-DOPA (mmol.L−1) | X4 | 0.02 (− 2.38) | 1.4 (− 1) | 2.4 (0) | 3.4 (+ 1) | 6.85 (+ 2.38) |
Copper sulfate (µmol.L−1) | X5 | 0.27 (− 2.38) | 7.5 (− 1) | 12.75 (0) | 18 (+ 1) | 25.23 (+ 2.38) |