This European Standard specifies a Karl Fischer titrimetric method for the determination of the water content of fertilizers based on the use of methanol as extracting medium.
The method is applicable to all solid mineral fertilizers. The result (KFM water) includes "free" water and extracted water of crystallization from the following components of fertilizers: calcium nitrate tetrahydrate (Ca(NO3)2 · 4H2O); calcium hydrogen phosphate dihydrate (CaHPO4 · 2H2O); calcium sulfate dihydrate (gypsum, CaSO4 · 2H2O), calcium sulfate hemihydrate (CaSO4 · 0,5H2O); magnesium sulfate heptahydrate (MgSO4 · 7H2O); potassium chloride magnesium sulfate water (1/1/2,75, Kainite, KCl · MgSO4 · 2,75H2O); potassium magnesium sulfate hexahydrate (Schoenite, K2SO4 · MgSO4 · 6H2O); potassium magnesium sulfate tetrahydrate (Leonite, K2SO4 · MgSO4 · 4H2O); potassium sulfate calcium sulfate monohydrate (Syngenite, K2SO4 · CaSO4 · H2O); potassium chloride magnesium chloride hexahydrate (Carnallite, KCl · MgCl2 · 6H2O); magnesium nitrate hexahydrate (Mg(NO3)2 · 6H2O).
Metal oxides and hydroxides soluble in methanol and pyridine will have an effect which can be corrected for, if their content is known.