Item	Content
Na2S2O5	95% min
SO2	65%
Fe	0.005 % max
Insoluble substance in water	0.05 % max
Heavy metal (Pb)	0.002 % max
As	0.0002 % max
PH	4.0-4.6

Sodium Metabisulfite Property: 1 White or yellowish crystalline powder, 2 wet the relative density of 1.4. Soluble in water glycerol, slightly soluble in ethanol. Damp easy to decompose, exposed to air easily oxidized into sulfate. Access to emit sulfur dioxide and acid generated the corresponding salts. Heated to 150 degrees decomposition
Use: 1 Printing and dyeing mordant; Antichlor in after fabric bleaching; 2 chemical and medicine reducer and sulfonating agent; 3 bleaching agent of bamboo, wood and paper fiber; 4 nonferrous metal dressing agent; Waste water finishing agent; 5 rubber coagulator; Alkyl spice aldehyde in spice industry; 6 depilating agent, softening agent and anti-wear agent in leather industry; 7 reducer of developer and protective agent of fixative in sensitization industry