China (Mainland) 
specification:(enterprise standard of china）
|
quality specification |
standard value |
||
|
analysis pure |
chemical pure |
industrial grade
|
|
|
operative norm |
white cryst.powder |
white cryst.powder |
white cryst. powder |
|
（%） ≥ |
99.8 |
99.6 |
99.4 |
|
moisture content（%） ≤ |
0.5 |
0.5 |
0.5 |
|
m.p℃ |
132-134 |
131-135 |
130-136 |
|
residue of ignition （%） ≤ |
0.025 |
0.05 |
0.1 |
|
insolubility in water |
clarify
|
clarify
|
clarify
|
|
sulfates (so²¯)）（%） ≤ |
0.005 |
0.01 |
0.01 |
|
chloride (cl)（%） ≤ |
0.001 |
0.002 |
0.002 |
|
gallic acid |
qualified |
qualified |
|
|
acetone solution |
light yellow to colorless colorless colorless colorless |
yellow to colorless |
|
|
ph |
4.0-4.4 |
3.9-4.5 |
|
|
heavy metal(pt) ≤ |
5.0 |
5.0 |
5.0 |
