Review Article
Heavy Metal and Trace Metal Analysis in Soil by Sequential Extraction: A Review of Procedures
Table 1
Operating conditions for sequential extraction procedures. H Acid mix = 5 mL HF, HClO4 3 mL, HNO3 2 mL.
(a) |
| | Time | Temp | Quantity | Tessier | Time | Temp | Quantity | BCR |
| | | | | 1 g | | | | 1 g | Exchangeable | 1 hr | continuous agitation | 8 mL | 1 mol MgCl2 pH 7.0 | 16 hr | w/constant agitation | 40 mL | 0.11 mol CH3COOH | | 8 mL | or 1 mol Na OAc pH 8.2 | Bound to Carbonates | 5 hr | continuous agitation-leached at rm temp. | 8 mL | 1 mol Na OAc pH 5.0 w/acetic acid | Bound to Iron and Manganese Oxides | 6 hr | | 20 mL | 0.3 mol Na2S2O4 + 0.175 mol Na-citrate + 0.025 mol H-citrate | 16 hr | w/constant agitation | 40 mL | 0.1 mol NH2OH*HCl pH 2 with HNO3 | | or occasional agitation | 20 mL | 0.04 mol NH2OH*HCl in 25% (v/v) HOAc |
| Bound to Organic Matter | 2 hr | with occasional agitation | 3 mL | 0.02 mol HNO3 | 1 hr | room temp. w/occ. Agitation | 10 mL | 8.8 mol H2O2 pH 2-3 | | 5 mL | 30% H2O2 pH 2 with HNO3 | | | 3 hr | with intermittent agitation | 3 mL | 30% H2O2 ph 2 with HNO3 | 1 hr | 85° degrees C | 10 mL | reduce vol. to less than 3 mL H2O2 pH 2-3 reduce vol. to 1 mL | | 1 hr | 30 min | continuous agitation | 5 mL | 3.2 mol NH4OAc in 20% (v/v) HNO3-dilute to 20 mL | 16 hr | w/constant agitation | 50 mL | 1 mol NH4OAc pH 2 w/HN |
| Residual | | | 1 mL Unk | HF-HClO4 5 : 1 HF-HClO4 10 : 1 HClO4 12 N HCl | | | | HF, HNO3, HClO4 |
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(b) |
| | Time | Temp | Quantity | Maiz-Short | Time | Temp | Quantity | Galán |
| | | | | 3 g | | | | 0.5 g | Exchangeable | | rm temp. | 10 mL | 0.01 mol CaCl2 | | 20°C w/continuous agitation | 35 mL | 1 M NH4OAc, pH 5 | 2 hr | suspend under agitation | 1 hr | Bound to Carbonates | 4 hr | | | 0.005 mol DTPA + | | Bound to Iron and Manganese Oxides | | rm temp. | | 0.01 mol CaCl2 + | | 96°C manual agitation every 30 min | 20 mL | 0.4 M NH2OH*HCl in CH3COOH 25% | | | | | |
| | | 2 mL | 0.1 mol TEA pH 7.3 | 6 hr | Bound to Organic Matter | | | | | 2 hr | 85°C w/manual agitation every 30 min | 3 mL | 0.2 M HNO3 | | | | | | 5 mL | 30% H2O2, pH 2 | | | | | 3 hr | | 3 mL | 30% H2O2 | | | | | 30 min | Continuous agitation | 5 mL | 30% H2O2 | Residual | | | | aqua regia-HF acid | 2 hr | | 10 mL | HF,HNO3,HCl 10 : 3 : 1 |
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(c) |
| | | | Time | Temp | Quantity | Canada |
| | | | | | | 1 g | Exchangeable | mobile | AEC | 6 hr | | 20 mL | 1.0 mol CH3CO2Na pH 5 | 6 hr | | 20 mL | 1.0 mol CH3CO2Na pH 5 | Bound to Carbonates | | Am Fe ox | 2 hr | 60°C vortex every 30 min | 20 mL | 20 mL 0.25 mol NH2OH*HCl in 0.05 mol HCl | Bound to Iron and Manganese Oxides | | 30 min | 60°C | 20 mL | 20 mL 0.25 mol NH2OH*HCl in 0.05 mol HCl | | Cry Fe ox | 3 hr | 90°C vortex every 20 min | 30 mL | 1.0 mol NH2OH*HCl in 25% CH3CO2H | Bound to Organic Matter | mobilisible | 1.5 hr | 90°C | 30 mL | 1.0 mol NH2OH*HCl in 25% CH3CO2H | | Org/Sulf | 30 min | | | 750 mg KClO3 and 5 mL 12 mol HCl vortex and add 10 mL HCl more | | | | | 15 mL H2O | | 20 min | 90°C | 10 mL | 4 mol HN |
| Residual | | silicates and residual | Unk | 200°C | 2 mL | 16 mol HNO3reduce to 0.5 mL | | 20 min | 90°C | 2 mL | 12 mol HCl | | 1 hr | 90°C | 10 mL | acid mix H | | overnight | Evap 70°C | | | | last bit | Rai 120°C | | | | 5–10 min | | 1 mL | 12 mol HCl | | | 3 mL | 16 mol HNO3 | | | 3 mL | 3 mL H2O and warm then bring up to 20 mL |
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