Sodium Metabisulfite, Sodium Metabisulphite, Sodium Pyrosulfite, SMBS,CAS7681-57-4, Na2S2O5, Food Grade, Industrial Grade, 97%,98%,99%,white powder,wa

It is applied in the pharmaceutical industry for the production of chloroform, solasulfone and benzaldehyde. In the rubber industry, it acts as a coagulant. In printing and dyeing industry, it is used as a dechlorinating agent after cotton bleaching and an auxiliary for cotton scouring. In leather industry, it is used for leather treatment to make the leather soft, plump and tough, with properties of water resistance, folding resistance and wear resistance. In chemical industry, it is used to produce hydroxyvanillin, hydroxylamine hydrochloride and other products. It is also used as a developer in the photographic industry.

When sodium metabisulfite is used for the synthesis of active pharmaceutical ingredients (APIs), it does not participate in the construction of drug molecular skeletons. It only serves as a process reagent (reducing agent, oxygen scavenger, decolorizing agent and dechlorinating agent), and is generally removed in subsequent processes via water washing, crystallization and filtration.

If trace sulfite residues remain in the finished active pharmaceutical ingredients, limit control for sulfite residues in the finished products shall also be implemented.

Sodium metabisulfite exhibits stronger reducing properties compared with sulfites, and its functions are similar to sodium sulfite. According to Chinese national regulations, it may be used in preserved fruits, biscuits, sugar, rock sugar, maltose, confectionery, glucose, liquid glucose, bamboo shoots, mushrooms and canned mushrooms, with a maximum usage level of 0.45 g/kg.

The residual content (calculated as SO₂) shall be less than 0.05 g/kg for preserved fruits, bamboo shoots, mushrooms, canned mushrooms, grape and blackcurrant concentrated juice; less than 0.1 g/kg for biscuits, sugar, vermicelli and other products; and no more than 0.2 g/kg for liquid glucose.

Relatively stable under dry and sealed conditions. Air‑ and moisture‑sensitive. It will gradually decompose and release sulfur dioxide when exposed to moist air, slowly oxidized into sodium sulfate. Thermal decomposition starts at 150 °C. Incompatible with strong acids and strong oxidizing agents. Toxic sulfur‑dioxide gas will be released upon contact with strong acids. Aqueous solution is unstable and decomposes easily on heating or exposure to air. Non‑combustible, but toxic sulfur‑oxide fumes may be generated upon thermal decomposition.

Storage: Store at +5 °C to +30 °C, keep tightly sealed, keep away from acids and strong oxidants.