Heavy Metal and Trace Metal Analysis in Soil by Sequential Extraction: A Review of Procedures

Table 2

Operating conditions for the modified GCS extraction procedures using 1 g of sample.

	Time	Temp	Quantity	Canada
				Benitez and Dubois [22]
Exchangeable	1.5 hrs	25°C	30 mL	0.1 mol NaNO3
	1.5 hrs	25°C	30 mL	0.1 mol NaNO3
Adsorbed	1.5 hrs	25°C	30 mL	1 mol Na OAc pH 5.0 w/CH3COOH
	1.5 hrs	25°C	30 mL	1 M Na OAc pH 5.0 w/CH3COOH
Organic	1.5 hrs	25°C	30 mL	0.1 mol Na4P2O7
	1.5 hrs	25°C	30 mL	0.1 mol Na4P2O7
Amorphous Oxyhydroxides	1.5 hrs	60°C	30 mL	0.25 mol NH2OH*HCl in 0.5 mol HCl
	1.5 hrs	60°C	30 mL	0.25 mol NH2OH*HCl in 0.5 mol HCl
Crystalline Oxides	1.5 hrs	90°C	30 mL	1 mol NH2OH*HCl in 25% H Oac
	1.5 hrs	90°C	30 mL	1 mol NH2OH*HCl in 25% H Oac
Residual	unk			HF, HNO3, HClO4