Item

Standard

Test result

Excellent Grade  

First-class goods

Qualified products

Nitrogen Content % ≥

21

21.0

20.5

21.1

Moisture %≤

0.2

0.3

1.0

0.1

Free acidity(H2SO4) %≤

0.03

0.05

0.20

0.03

     Fe content %≤

0.007

／

／

0.002

   Arsenic  content % ≤

0.00005

／

／

0.00001

   Heavy metal % ≤

0.005

／

／

0.005

Water-insoluble content %≤

     0.01

／

／

0.004