Appearance White or off-white granule crystal
N content (dry basis)% >= 21.0 21.0 20.5
Water(H2O)content%<= 0.2 0.3 1.0
Free acid(H2SO4)%<= 0.03 0.05 0.20
Iron Fe)content%<= 0.007 -- --
Arsenic As)content%<= 0.00005 -- --
Heavy metal(pb)% <= 0.005 -- --
Insoluble substance in water
%<= 0.01 -- --