Chemical Specifications Appearance Colorless Crystals. Assay (on anhydrous basis) Min 99.9% Alcohol insoluble matter Passes test Clarity of solution Passes ACS test Chloride (Cl) Max 0.0005% Sulphate (SO4) Max 0.002% Alkalies and other metals Max 0.05% Bismuth (Bi) Max 0.0005% Copper (Cu) Max 0.0002% Iron (Fe) Max 0.0002% Sodium (Na) Max 0.002% Lead (Pb) Max 0.001% Free acid Passes test Substance not precipitated by HCl Max 0.01%