Appearance white crystalline powder Transmittance Not less than95.0% Chloride (Cl) Not more than 0.02% Ammonium (NH4) Not more than 0.02% Sulfate (SO4) Not more than 0.02% Iron (Fe) Not more than 30ppm Heavy metal(Pb) Not more than 10ppm Arsenic(As2O3) Not more than 1ppm Loss on drying Not more than 0.20% Residue on ignition(sulfated) Not more than 0.1% Assay 98.5 to101.5%