Appearance A clear colorless liquid Assay (alkalimetric) Min 48% Residue on ignition Max 0.0001% Fluorosilicic acid (H2SiF6) Max 0.001% Heavy metal (as Pb) Max 0.00005% Copper (Cu) Max 0.00001% Iron (Fe) Max 0.00001% Potassium (K) Max 0.00001% Sodium (Na) Max 0.00001% Chloride (Cl) Max 0.00001% Phosphate (PO4) Max 0.00001% Sulphite (as SO3) Max 0.00001% Sulphate (SO4) Max 0.00001%