Overview
Sodium metabisulfite (CAS 7681-57-4 ), also known as sodium pyrosulfite and sold under the abbreviation SMBS, is an inorganic sulfite salt used across food, industrial, and water treatment sectors. It serves as a preservative, antioxidant, and reducing agent.
As E223 , it is a regulated food additive recognized in major international markets. Its ability to release sulfur dioxide under controlled conditions underpins its function across multiple industries and specialized chemical processes.
In food and beverage production, E223 prevents oxidative browning and microbial spoilage in dried fruits, wines, seafood, and fruit juices. This ensures product longevity and maintains the aesthetic quality of processed goods.
Water treatment plants use SMBS to neutralize residual chlorine in municipal and industrial effluent streams before discharge or further processing. This step is critical for environmental safety and protecting downstream equipment.
Textile and leather processors apply it as a bleaching and reducing agent in dye stripping and chrome tanning operations. It provides consistent results in heavy industrial manufacturing environments requiring high-purity chemical inputs.
In pharmaceutical manufacturing, it functions as an antioxidant stabilizer in injectable formulations and oral solutions. This is essential where oxygen-sensitive active ingredients require protection to maintain their therapeutic efficacy.
Sodium metabisulfite is supplied as a white to off-white crystalline powder or fine granules. Standard commercial grades include food-grade ( FCC -compliant), USP / BP pharmaceutical grade, and technical grade for industrial applications.
Bulk supply is available in 25 kg bags, with food and pharma grades accompanied by full compliance documentation. Our logistics network ensures reliable delivery for large-scale manufacturing and chemical processing facilities worldwide.
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Physical Properties
| Melting Point | 150 °C (decomp) |
| Density | 1.4 g/cm³ |
| Appearance | Sodium metabisulfite is a white crystalline powder. Sulfur dioxide odor. It may be considered the anhydride of 2 molecules of sodium disulfite. |
| Color | White to slightly yellow |
| Odor | Sulphorous |
| Form | Powder/Solid |
| Water Solubility | 540 g/L (20 ºC) |
| Refractive Index | 1.474 |
| pH | 3.5-5 (50g/l, H2O, 20℃) |
Safety & Handling
Danger GHS05 GHS07 GHS08 Hazard Statements H302 Harmful if swallowed H317 May cause an allergic skin reaction H318 Causes serious eye damage H320 Causes eye irritation H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled H335 May cause respiratory irritation H372 Causes damage to organs through prolonged or repeated exposure H402 Harmful to aquatic life H412 Harmful to aquatic life with long lasting effects Precautionary Statements P233 Keep container tightly closed. P260 Do not breathe dust/fume/gas/mist/vapours/spray. P261 Avoid breathing dust/fume/gas/mist/vapours/spray. P264 Wash … thoroughly after handling. P270 Do not eat, drink or smoke when using this product. P271 Use only outdoors or in a well-ventilated area. P272 Contaminated work clothing should not be allowed out of the workplace. P273 Avoid release to the environment. P280 Wear protective gloves/protective clothing/eye protection/face protection. P284 In case of inadequate ventilation wear respiratory protection. P317 Get emergency medical help. P319 Get medical advice/attention if you feel unwell. P321 Specific treatment (see … on this label). P330 Rinse mouth. P403 Store in a well-ventilated place. P405 Store locked up. P501 Dispose of contents/container in accordance with local regulations. P264+P265 Wash … thoroughly after handling. P301+P317 Get emergency medical help. P302+P352 IF ON SKIN: Wash with plenty of water. P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing. P333+P317 Get emergency medical help. P337+P317 If eye irritation persists: Get medical advice/attention. Get emergency medical help. P342+P316 Get emergency medical help immediately. P362+P364 Take off contaminated clothing and wash it before reuse. P403+P233 Store in a well-ventilated place. Keep container tightly closed. P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. P305+P354+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
Trade & Regulatory
| HS Code | 28323010 |
| Storage Class | 13 - Non Combustible Solids |
| WGK (Germany) | 1 |
Other Names
Related Products
Chemical Properties
- CAS Number
- 7681-57-4
- EC Number
- 231-673-0
- Mol. Weight
- 190.11
- HS Code
- 28323010
- Category
- Oxidizers & Peroxides