Table 3 Step-by-step BCR extraction procedure.
From: Characterization and evaluation of Fe2+ and Mn2+ in reservoirs and sediments in the Jianghuai Region
Steps | Forms of heavy metals | Extractant | Volume/ml | Temperature/°C | Test procedure |
|---|---|---|---|---|---|
1 | Commutable State | 0.11 mol/L Acetic acid solution | 20 | 22 ± 0.5 | Shake continuously for 16 h, then centrifuge at 4000 rpm for 15 min. Remove a portion of the supernatant, filter it (using a 0.45 μm filter membrane, same below), and store it at 4 °C for later testing. Add 20 ml of deionized water to the residue, wash it, and centrifuge for 15 min. Discard the wash solution and retain the residue for use in the next step |
2 | Oxidizable State | 0.1 mol/L hydroxylamine hydrochloride (adjusted to pH 2 using 2 mol/L HNO₃) | 20 | 22 ± 0.5 | Shake continuously for 16 h, then centrifuge at 4000 rpm for 15 min. Remove a portion of the supernatant, filter it, and store at 4 °C for later testing. Add 20 mL of deionized water to the residue, wash it, and centrifuge for 15 min. Discard the wash solution and retain the residue for use in Step 3 |
3 | Reduced State | 8.8 mol/L H2O2 | 20 | 22 ± 0.5 | First add 5 mL of 8.8 mol/L H₂O₂, let stand at 25 °C for 1 h, then add another 5 mL of 8.8 mol/L H₂O₂ and incubate in a water bath at 85 °C for 1 h. Add 20 mL of 1 mol/L NH₄OAc and shake at room temperature for 16 h. Centrifuge at 4000 rpm for 15 min. Remove a portion of the supernatant, filter it (using a 0.45 μm filter membrane; same applies below), and store it at 4 °C for later testing. Add 20 mL of deionized water to the residue, wash it, and centrifuge for 15 min. Discard the washing solution; retain the residue for use in Step 4 |
4 | Residual State | HNO3 | 5 | 185 ± 0.5 | Digest for 8 h. After digestion, dilute the solution to 100 mL in a polyethylene volumetric flask, adjust the volume, and filter a portion of the solution for analysis |
HF | 5 | ||||
HClO4 | 2 |
