| Methods | Dose (mg·kg−1) | NVef | MTf | NVef | MTf |
| Cu (II) in mg·kg−1 | Cr (III) in mg·kg−1 | ||||
| Sulfuric attack | 0 | 350.35 | 311.00 | 35.70 | 36.80 |
| 100 | 406.20 | 355.45 | 97.00 | 93.90 | |
| 400 | 794.20 | 509.35 | 318.05 | 304.15 | |
| 800 | 1087.25 | 864.65 | 551.40 | 518.95 | |
| Mehlich-1 | 0 | 43.78 | 26.64 | 0.74 | 0.00 |
| 100 | 101.475 | 70.24 | 2.53 | 3.07 | |
| 400 | 308.17 | 293.89 | 9.42 | 8.52 | |
| 800 | 478.17 | 475.44 | 32.44 | 16.00 | |
| KCl 1 mol·L−1 | 0 | 1.91 | 3.45 | ND | ND |
| 100 | 3.03 | 4.22 | ND | ND | |
| 400 | 15.24 | 11.58 | ND | ND | |
| 800 | 43.05 | 34.85 | ND | ND | |
| Distilled and deionized water | 0 | 0.42 | 0.28 | ND | ND |
| 100 | 0.45 | 0.90 | ND | ND | |
| 400 | 0.98 | 1.23 | ND | ND | |
| 800 | 2.76 | 3.06 | ND | ND | |
| CaCl2 0.01 mol·L−1 | 0 | 0.38 | 0.41 | ND | ND |
| 100 | 0.68 | 0.53 | ND | ND | |
| 400 | 4.30 | 3.44 | ND | ND | |
| 800 | 14.72 | 11.96 | ND | ND | |