|
Test Item
|
Standard Request.
|
Results of Test
|
|
Appearance
|
White or light yellow
|
Meet the demand
|
|
crystalline powder
|
||
|
Content(Na2S2O5%)
|
≥ 95%
|
97.85%
|
|
SO2%
|
≥ 65%
|
65.86%
|
|
Fe%
|
≤ 0.005%
|
0.00%
|
|
Insoluble substance
|
≤ 0.05%
|
0.01%
|
|
in water%
|
||
|
Heavy metal (Pb)%
|
≤ 0.002%
|
0.00%
|
|
As%
|
≤ 0.0002%
|
0.00%
|
|
PH
|
4.0-4.6
|
4.4
|
