Sodium Metabisulfite is an inorganic sulfur-containing cosmetic ingredient used in formulation systems primarily for its antioxidant, reducing and preservative functionality. Its INCI name is SODIUM METABISULFITE. It is identified by CAS No. 7681-57-4, EC No. 231-673-0, and has the molecular formula Na₂S₂O₅ with a molecular weight of 190.11 g/mol. COSMILE Europe identifies Sodium Metabisulfite as a synthetic cosmetic ingredient with antioxidant, fragrance-functional, preservative and reducing functions.
Sodium Metabisulfite is also known as Sodium Pyrosulfite, Sodium Disulfite and Disodium Pyrosulfite. It is normally supplied as white crystals or crystalline powder and has the characteristic odour associated with sulfur dioxide. It is freely soluble in water and slightly soluble in ethanol.
Sodium Metabisulfite consists of sodium and metabisulfite ions and can release sulfur dioxide under appropriate conditions. The chemical formula is Na₂S₂O₅ and the formula weight is 190.11. JECFA and the European food-additive specification both identify CAS No. 7681-57-4 and INS 223 for this substance.
An important technical consideration is that Sodium Metabisulfite should not be given a conventional organic-compound HPLC assay simply because it is a chemical raw material. The USP-NF monograph defines Sodium Metabisulfite using its equivalent sulfur-dioxide content and uses a residual titration with iodine, rather than an HPLC assay. USP specifies an equivalent SO₂ content of 65.0–67.4%.
Sodium Metabisulfite has several documented cosmetic functions. COSMILE Europe identifies it as an antioxidant, helping inhibit oxidation and deterioration of formulation components. It is also classified as a reducing ingredient, meaning it can change the chemical nature of another substance by removing oxygen or adding hydrogen. COSMILE additionally lists preservative and fragrance-functional roles.
Its reducing properties can be useful in formulations where oxidation control is important. Sulfite-based ingredients can also contribute to preservation systems by controlling conditions that support microbial deterioration. However, the exact role of Sodium Metabisulfite should be determined according to the finished formulation and the applicable regulatory category rather than assuming that its antioxidant and preservative functions are interchangeable.
Sodium Metabisulfite Cosmetic Ingredient can be considered for a range of cosmetic and personal-care formulation systems, including:
Its practical application depends on formulation pH, the presence of oxidizing materials, compatibility with other ingredients and the intended concentration.
Sodium Metabisulfite is also widely recognized outside cosmetics as an antioxidant and preservative. JECFA classifies it as an antioxidant and preservative and identifies it as INS 223.
Sodium Metabisulfite is particularly sensitive to formulation conditions because sulfite chemistry is influenced by pH, oxidation and sulfur-dioxide release. Formulators should therefore evaluate the actual pH and stability of the finished system rather than relying only on the raw-material specification.
Current EU food-additive specifications give a pH range of 4.0–5.5 for a 10% aqueous solution, while JECFA's monograph gives 4.0–4.5 for a 1-in-10 solution. These are specification references rather than universal limits for every cosmetic grade.
Moisture exposure should also be controlled during storage because sulfite materials can be affected by environmental conditions. Tight packaging and suitable storage conditions are therefore important for maintaining raw-material quality.
Sodium Metabisulfite is a specialty cosmetic raw material and multifunctional ingredient for manufacturers working with antioxidant, reducing and preservation systems. Businesses sourcing Sodium Metabisulfite in India may require controlled purity, sulfur-dioxide equivalence, pH, thiosulfate, elemental impurity and water-insoluble specifications.
For B2B procurement, relevant searches include Sodium Metabisulfite cosmetic ingredient manufacturer in India, Sodium Metabisulfite supplier India, Sodium Metabisulfite manufacturing in India, Sodium Metabisulfite cosmetic raw material supplier, Sodium Metabisulfite personal care ingredient supplier and bulk Sodium Metabisulfite ingredient supply.
The commercial grade should be selected according to the intended formulation and applicable regulatory requirements. Food, pharmaceutical and cosmetic specifications should not be treated as automatically interchangeable.
| Parameter | Specification |
|---|---|
| Appearance | White or colourless crystals / white powder |
| Assay (HPLC) | NLT 95.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| pH (1% Solution) | 5.0 – 7.0 |
| Water Content | NMT 1.0% |