|
Appearance
|
White crystalline powder
|
|
Assay (iodometric)
|
96.5 - 100%
|
|
Assay (as SO2; iodometric)
|
65 - 67.4%
|
|
Identity (acc. to pharmacopoeias)
|
Passes test
|
|
pH (5% solution in water)
|
3.5 - 5.0
|
|
Appearance of solution
|
Passes test
|
|
Insoluble matter in water
|
Max 0.025%
|
|
Chloride (Cl)
|
Max 0.02%
|
|
Thiosulphate (S2O3)
|
Max 0.05%
|
|
Heavy metal (as Pb)
|
Max 0.002%
|
|
Arsenic (As)
|
Max 0.0004%
|
|
Iron (Fe)
|
Max 0.002%
|