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	22^∘C±5^∘ 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	22^∘C+5^∘ w/constant agitation	40 mL	0.1 mol NH2OH*HCl pH 2 with HNO3
		or 96^∘±3 occasional; agitation	20 mL	0.04 mol NH2OH*HCl in 25% (v/v) HOAc
Bound to Organic Matter	2 hr	85^∘±2 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	85^∘±2 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	22^∘C+5^∘ w/constant agitation	50 mL	1 mol NH4OAc pH 2 w/HNO3
Residual			1 mL Unk	HF-HClO4 5 : 1 HF-HClO4 10 : 1 HClO4 12 N HCl				HF, HNO3, HClO4

(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

(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 HNO3
Residual		silicates and residual	Unk	200°C	2 mL	16 mol HNO3∼reduce 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