1 Scope
This International Standard is applicable to as-received (field-moist) samples and specifies two different procedures for the liberation of cyanide from the soil:
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— direct liberation of hydrogen cyanide using orthophosphoric acid (normative);
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— extraction with sodium hydroxide solution and subsequent liberation using orthophosphoric acid (informative, see Annex B).
The liberated cyanide is determined either by a photometric method or a titrimetric method using an indicator.
The method is applicable to all types of soil.
Under the conditions specified in this International Standard, the lower limit of application is 0,5 mg/kg of total cyanide (expressed on the as-received basis) for photometric determination and 10 mg/kg for titrimetric determination.
NOTE Using the alkaline extraction followed by liberation using phosphoric acid, the lower limit of application is 1 mg/kg of total cyanide (expressed on the as-received basis) for photometric determination and 30 mg/kg for titrimetric determination.