Agricultural grade Purity: 21%min White powder Top manufacturer's supply Ammonium ... Molecular Formula:(NH4)2SO4, Molecular Weight:132.13,Appearance: white crystals, N: 21% min;Free acid as H2SO4 ... content, % ≤0.007--As content,% ≤0.00005--Heavy metal(Pb)content,% ≤0.005--Water insolubles,% ≤0.01--Note: ... check the content of Fe,As,heavy metal and water insolubles. Ammonium sulphate 21%min white powder