Appearance White crystalline powder Assay (alkalimetric) Min 99.5% Water (by KF) Max 1.0% Sulphated ash Max 0.1% Iron (Fe) Max 0.005% Heavy metal (as Pb) Max 0.001% Chloride (Cl) Max 0.005% Sulphate (SO4) Max 0.015% Reaction against H2SO4 Passes test