Item Standard Appearance White powder State of Solution (Transmittance) Not less than 95.0% Chloride (Cl) Not more than0.02% Heavy metal(Pb) Not more than 15ppm Arsenic(As2O3) Not more than 2ppm Loss on drying Not more than 0.20% Residue on ignition(sulfated) Not more than 0.20% Assay 98.0 to101.0%