This International Standard is applicable to as received (field moist) samples and specifies two differentprocedures for the liberation of cyanide from the soil:. direct liberation of hydrogen cyanide using orthophosphoric acid (normative). 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 totalcyanide (expressed on the as rece