International Journal of Analytical Chemistry / 2010 / Article / Tab 1

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.


1 g1 g
Exchangeable1 hrcontinuous agitation8 mL1 mol MgCl2 pH 7.016 hr w/constant agitation40 mL0.11 mol CH3COOH
8 mLor 1 mol Na OAc pH 8.2
Bound to Carbonates5 hrcontinuous agitation-leached at rm temp.8 mL1 mol Na OAc pH 5.0 w/acetic acid
Bound to Iron and Manganese Oxides6 hr20 mL0.3 mol Na2S2O4 + 0.175 mol Na-citrate + 0.025 mol H-citrate16 hr w/constant agitation40 mL0.1 mol NH2OH*HCl pH 2 with HNO3
or occasional
20 mL0.04 mol NH2OH*HCl in 25% (v/v) HOAc

Bound to Organic Matter2 hr with occasional agitation3 mL0.02 mol HNO31 hrroom temp. w/occ. Agitation10 mL8.8 mol H2O2 pH 2-3
5 mL30% H2O2 pH 2 with HNO3
3 hr with intermittent agitation3 mL30% H2O2 ph 2 with HNO31 hr85° degrees C10 mLreduce vol. to less than 3 mL H2O2 pH 2-3 reduce vol. to 1 mL
1 hr
30 mincontinuous agitation5 mL3.2 mol NH4OAc in 20% (v/v) HNO3-dilute to 20 mL16 hr  w/constant agitation50 mL1 mol NH4OAc pH 2 w/HN

Residual1 mL UnkHF-HClO4 5 : 1 HF-HClO4 10 : 1 HClO4 12 N HClHF, HNO3, HClO4



3 g0.5 g
Exchangeablerm temp.10 mL0.01 mol CaCl220°C w/continuous agitation35 mL1 M NH4OAc, pH 5
2 hrsuspend under agitation1 hr
Bound to Carbonates4 hr0.005 mol DTPA +
Bound to Iron and Manganese Oxidesrm temp.0.01 mol CaCl2 +96°C manual agitation every 30 min20 mL0.4 M NH2OH*HCl in CH3COOH 25%

2 mL0.1 mol TEA pH 7.36 hr
Bound to Organic Matter2 hr85°C w/manual agitation every 30 min3 mL0.2 M HNO3
5 mL30% H2O2, pH 2
3 hr3 mL30% H2O2
30 minContinuous agitation5 mL30% H2O2
Residualaqua regia-HF acid2 hr10 mLHF,HNO3,HCl 10  :  3  :  1



1 g
ExchangeablemobileAEC6 hr20 mL1.0 mol CH3CO2Na pH 5
6 hr20 mL1.0 mol CH3CO2Na pH 5
Bound to CarbonatesAm Fe ox2 hr60°C vortex every 30 min20 mL20 mL 0.25 mol NH2OH*HCl in 0.05 mol HCl
Bound to Iron and Manganese Oxides30 min60°C20 mL20 mL 0.25 mol NH2OH*HCl in 0.05 mol HCl
Cry Fe ox3 hr90°C vortex every 20 min30 mL1.0 mol NH2OH*HCl in 25% CH3CO2H
Bound to Organic Mattermobilisible1.5 hr90°C30 mL1.0 mol NH2OH*HCl in 25% CH3CO2H
Org/Sulf30 min750 mg KClO3 and 5 mL 12 mol HCl vortex and add 10 mL HCl more
15 mL H2O
20 min90°C10 mL4 mol HN

Residualsilicates and residualUnk200°C2 mL16 mol HNO3 reduce to 0.5 mL
20 min90°C2 mL12 mol HCl
1 hr90°C10 mLacid mix H
overnightEvap 70°C
last bitRai 120°C
5–10 min1 mL12 mol HCl
3 mL16 mol HNO3
3 mL3 mL H2O and warm then bring up to 20 mL

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