... N content:21% min Caprolactam grade Water: 0.2% max White flowing crystal Sulphate ammoniumAmmonium ... 21% min;Free acid as H2SO4:0.03% max,Moisture:0.3% max,Packing:50kgs plastic woven ... H2O),% 0.20.31.0Free acid(H2SO4)content,% ≤0.030.050.20Fe content, % ≤0.007--As content,% ≤0.00005-- ... Heavy metal(Pb)content,% ≤0.005--Water insolubles,% ≤0.01-- ...