Chemical Specifications Appearance White crystalline powder Assay (acidimetric) 98 - 101% Chloride (Cl) Max 0.005% Nitrate (NO3) Max 0.002% Sulphate (SO4) Max 0.01% Arsenic (As) Max 0.0001% Heavy metal (as Pb) Max 0.005% Iron (Fe) Max 0.001%