Sodium metabisulfite Cas 7681-57-4
Product Description
Product Name: Sodium metabisulfite
Synonyms: Sodium pyrosulfite
CAS No. 7681-57-4
M.F.: 2Na.O5S2
M.W.: 190.11
EINECS: 231-673-0
Specifications
Items | Specifications | Results |
Characters | This product is a colorless to off-white crystalline or crystalline powder, readily soluble in water and slightly soluble in ethanol. | The off-white crystalline powder is readily soluble in water and slightly soluble in ethanol. |
Identification | The solution shows the reactions of sulfate identification (1) and (3) | Positive reaction |
This product shows a flame reaction with sodium salts | Conforms |
PH | 3.5~5.0 | 4.1 |
Clarity and color | Clear and colorless | Clear and colorless |
chloride | NMT 0.05% | ＜0.05% |
thiosulfate | NMT 0.05% | ＜0.05% |
ferric salt | NMT 0.002% | ＜0.002% |
Heavy Metal | NMT 20 per million | ＜20 per milion |
arsenic salt | NMT0.0001% | ＜0.0001% |
bacterial endotoxin | ＜5EU/mg | ＜5EU/mg |
Total aerobic bacteria count | NMT103cfu/g | ＜10cfu/g |
Assay | NLT 95.0% | 97.3% |
Conclusion | The product conforms to the above specifications. |
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Sodium metabisulfite (or sodium pyrosulfite) is an inorganic compound with the chemical formula Na₂S₂O₅. It is a white or yellowish-white crystalline powder with a sharp, pungent sulfur dioxide (SO₂) odor.
Key Chemical Behavior:
It is not stable in water and readily decomposes, releasing sulfur dioxide (SO₂). This property is the source of its usefulness.
Major Uses of Sodium Metabisulfite
1. Food Industry (Common Food Additive: E223)
It is widely used as a preservative, antioxidant, and bleaching agent.
Preservative: Inhibits the growth of bacteria, yeasts, and molds. Extends shelf life.
Antioxidant: Prevents browning (enzymatic and non-enzymatic) in fruits and vegetables. Used in:
Dried fruits (e.g., apricots, golden raisins)
Potato products (french fries, dehydrated potatoes)
Fruit juices, concentrates, and syrups
Wine and cider (see below)
Bleaching Agent: Used in the production of some sugars (like beet sugar) and maraschino cherries to achieve a bright color.
2. Winemaking & Brewing (Critical Tool)
It is indispensable in these industries, where it is often referred to simply as "sulfites" or "campden tablets" (a tablet form).
Antimicrobial Agent: Kills or inhibits wild yeasts and bacteria, allowing cultivated yeast to ferment without competition.
Antioxidant: Protects wine from oxidation, which spoils color and flavor (prevents "browning" of white wines).
Stabilizer: Halts fermentation at a desired point and prevents refermentation in the bottle.
Equipment Sanitizer: Used to sanitize fermentation vessels, barrels, and bottles.
3. Pharmaceutical Industry
Antioxidant: Used as an excipient in some medications (injectable drugs, liquid formulations) to prevent the active ingredient from oxidizing and degrading.
Sterilizing Agent: For some equipment.
4. Water Treatment
Dechlorination: Removes excess chlorine (and chloramines) from water. It is a common chemical for neutralizing chlorine in wastewater, in industrial processes, and even in home brewing (to make tap water safe for yeast).
Oxygen Scavenger: Used in boilers and oil recovery to remove dissolved oxygen, preventing corrosion.
5. Photography (Traditional Film Development)
6. Textile & Chemical Manufacturing
Bleaching Agent: For wool, silk, and certain synthetic fibers.
Reducing Agent: In various chemical synthesis processes.
Waste Treatment: Neutralizes peroxide bleaches and removes heavy metals (e.g., chromium) from wastewater.
Important Safety & Regulatory Information
Allergies and Sensitivities
"Contains Sulfites" Warning: In many countries, foods and beverages containing more than 10 ppm SO₂ must carry this label.
Asthma Risk: A small subset of the population (particularly asthmatics, estimated ~3-10%) can have severe sulfite sensitivity, leading to breathing difficulties, wheezing, and in rare cases, anaphylaxis.
Generally Recognized as Safe (GRAS): For the vast majority of people, it is safe when consumed at regulated levels.
Handling Precautions
Irritant: Powder can irritate eyes, skin, and respiratory tract. Use in well-ventilated areas.
Toxic Gas Release: NEVER MIX WITH ACIDS (like vinegar, bleach, or hydrochloric acid). This mixture produces toxic sulfur dioxide gas, which can cause severe respiratory distress.
Corrosive to Metals: Releases SO₂ in moist air, which can corrode metals.
Comparison with Related Compounds
| Compound | Formula | Primary Use Context | Relationship |
|---|
| Sodium Metabisulfite | Na₂S₂O₅ | Versatile; food (E223), winemaking, water treatment, photography. Contains ~67% SO₂. | The most common solid source of SO₂; dissociates to bisulfite in solution. |
| Sodium Bisulfite | NaHSO₃ | Very similar to metabisulfite, often used interchangeably. Contains ~61% SO₂. | The form metabisulfite creates in water. Often a liquid solution in industry. |
| Sodium Sulfite | Na₂SO₃ | Paper pulping, water treatment, food preservative. | Releases less SO₂, more alkaline. |
| Potassium Metabisulfite | K₂S₂O₅ | Identical uses, especially in winemaking (preferred by some for potassium sensitivity). | Potassium version; used where sodium intake is a concern. |
Summary
Sodium metabisulfite is a versatile reducing agent, preservative, and antioxidant whose power comes from its controlled release of sulfur dioxide (SO₂). Its primary roles are:
Preserving Food & Drink: Preventing spoilage and browning.
Enabling Winemaking: As an antimicrobial and antioxidant.
Treating Water: As a dechlorinating agent.
Industrial Chemical: In textiles, photography, and as a reducing agent.
Its use is strictly regulated in food due to potential allergenic reactions in sensitive individuals, but it remains a critical and legal additive worldwide.
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Different products have different MOQ, such as:
1).Peptide products, the MOQ is 1 gram level
2).Liquid products, the MOQ is usually 50-100ML
3).API, the MOQ is 1KG
4).Intermediate products and conventional product, the MOQ is 1KG; custom-tailored products, the MOQ depends on the production process.
5).Food additives and vitamin, the MOQ is usually one package: such as Vitamin C is 25KG / drum, Vitamin E oil or Vitamin A oil is 5KG/bag;Vitamin E powder or Vitamin A powder is 20KG / cartons.
6).Agrochemical , the MOQ is 1KG, except preparations.
6.How do we take the quality complaint ?
First of all, our quality control will reduce the quality issue to near zero. If there is a quality problem caused by us, we will send you free goods for replacement or compensate your loss.
Company Information
Company profile
Wuhan Fortuna Chemical Co.,Ltd established in 2006, is a big integrative chemical enterprise being engaged in Pharmaceutical & its intermediates, Food/Feed additives, Fine chemicals in distributing the products of our own company and affiliated enterprises, are the members of Hubei E-commerce Chamber.
Our company has professional persons who major in chemical R&D and sicentific management, supply fine chemical products with high quality and close service, also supply custom-tailored products according to our clients’ requirement.
We have a positive and self-motivated management work team with a common philosophy, caring and commitment through teamwork, our team strive to achieve success in delighting our clients and ourselves.
Since Wuhan Fortuna Chemical Co., Ltd founded, we continuously innovate our products and improve our service, sales network. Hence, we initiate the first sale mode on net in China, which is the retail trade of small package bring along wholesale of diversified management modes. Our products are exported widely to South Korea, Vietnam, Australia, Europe and South America, highly recommended by our clients.
We insist on the management creed “Market is our compass, Quality is our life, Credit is our soul”. Clients’ trust is our forward powder, their satisfaction is our struggling goal.
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