Appearance Slightly yellow colored powder Assay Min 99.5% Chloride (Cl) Max 0.001% Sulphate (SO4) Max 0.005% Total nitrogen (N) Max 0.002% Heavy metal (as Pb) Max 0.002% Iron (Fe) Max 0.001% Sodium (Na) Max 0.02% Potassium (K) Max 0.02% Loss on ignition (at 750°C) Max 16.0%