Table 2.
Design and results of orthogonal test.
| Trial no. | Factor | Average recovery (%) | ||
|---|---|---|---|---|
| Aa | Bb | Cc | ||
| 1 | 1 | 1 | 1 | 79.6 |
| 2 | 1 | 2 | 2 | 84.6 |
| 3 | 1 | 3 | 3 | 83.2 |
| 4 | 2 | 1 | 2 | 78.4 |
| 5 | 2 | 2 | 3 | 78.3 |
| 6 | 2 | 3 | 1 | 70.6 |
| 7 | 3 | 1 | 3 | 69.4 |
| 8 | 3 | 2 | 1 | 67.3 |
| 9 | 3 | 3 | 2 | 70.5 |
| K 1 | 82.5 | 75.8 | 72.5 | |
| K 2 | 75.8 | 76.8 | 77.8 | |
| K 3 | 69.1 | 74.8 | 77.0 | |
| Range | 13.4 | 2.0 | 5.3 | |
K i , mean effect of each factor at level i (i = 1, 2, 3). a Factor A, extraction solvent; level 1, acetonitrile; level 2, petroleum ether; level 3, acetone. b Factor B, volume; level 1, 10 mL; level 2, 16 mL; level 3, 20 mL. c Factor C, extraction time; level 1, 15 min; level 2, 20 min; level 3, 25 min.