... after-sale service 1, Technical indexItemIndexAppearancewhite crystalline powderAssay, %99.0Free acid, %≤0.01Cl,%≤0.00004Heavy metals (Pb),%≤0.0005Fe,%≤0.0005Mn ... ).Others: Also used in food, photo, storage battery industry, sulfuric acid industry, fat and oil industry. Storage: Sealed tightly, kept in ...