Potassium Metabisulfite is an inorganic sulfur-containing cosmetic ingredient used in selected personal-care formulations for its reducing and preservative functions. Its INCI name is POTASSIUM METABISULFITE. It is identified by CAS No. 16731-55-8, has the molecular formula K₂S₂O₅, and a formula weight of approximately 222.33 g/mol. It is also known as Potassium Disulfite, Potassium Pyrosulfite and Dipotassium Disulfite.
COSMILE Europe identifies Potassium Metabisulfite as a synthetic cosmetic ingredient with preservative, reducing, and hair-waving or hair-straightening functions. Its reducing action is associated with chemical systems where controlled modification of other substances is required.
Potassium Metabisulfite is different from Sodium Metabisulfite and Sodium Sulfite. Although these sulfite-based materials have related chemistry, their cation, molecular formula, molecular weight and specifications are different and they should therefore have separate product specifications.
Potassium Metabisulfite is the dipotassium salt of disulfurous acid and is represented by K₂S₂O₅. JECFA describes it as colourless free-flowing crystals, crystalline powder or granules, usually having an odour of sulfur dioxide. It is soluble in water and insoluble in ethanol.
The current European food-additive specification identifies Potassium Metabisulfite as containing not less than 90% K₂S₂O₅ and not less than 51.8% SO₂, with the remainder composed almost entirely of potassium sulfate. JECFA separately specifies an assay of not less than 90%.
For this inorganic sulfite salt, a conventional organic-compound HPLC assay should not automatically be entered into the CMS. USP describes the material in terms of its sulfur-dioxide equivalence, and its assay procedure is based on iodometric titration rather than a conventional HPLC assay.
Potassium Metabisulfite has documented preservative and reducing functions in cosmetics. As a reducing ingredient, it can alter the chemical nature of another material through reduction. COSMILE also identifies its use in hair-waving or hair-straightening systems where chemical modification of the hair structure is required.
Its preservative functionality is particularly relevant to formulations where sulfite chemistry is part of the microbial-control system. The finished product should nevertheless be evaluated as a complete preservation system rather than assuming that the raw material alone provides universal preservation.
Potassium Metabisulfite Cosmetic Ingredient can be considered for selected personal-care and formulation systems, including:
Its actual concentration and role depend on formulation chemistry, pH, processing conditions and the regulatory requirements of the destination market. COSMILE specifically documents its cosmetic use as a preservative, reducing ingredient and hair-waving/straightening ingredient.
Potassium Metabisulfite should be handled as a reactive sulfite material. It can gradually oxidize in air, and formulation performance can therefore be influenced by storage conditions, exposure to oxygen and the chemical environment. The FCC describes Potassium Metabisulfite as gradually oxidizing in air to sulfate.
The pH of aqueous solutions is an important quality and formulation parameter. The current EU food-additive specification gives a pH of 8.5–11.5 for a 10% aqueous solution, while the JECFA reference gives 8.5–10.0 for a 1-in-10 solution. These values are specification references and should not automatically be presented as the specification of every cosmetic grade.
Moisture, thiosulfate and elemental impurities should also be controlled. The exact specification should be matched to the commercial grade and the intended cosmetic application.
Potassium Metabisulfite is a specialty cosmetic ingredient and formulation raw material requiring controlled identity, sulfur-dioxide equivalence and impurity specifications. Businesses sourcing Potassium Metabisulfite in India may require technical documentation, batch-specific Certificate of Analysis and a specification appropriate to the intended personal-care application.
For B2B sourcing, relevant searches include Potassium Metabisulfite cosmetic ingredient manufacturer in India, Potassium Metabisulfite supplier India, Potassium Metabisulfite manufacturing in India, Potassium Metabisulfite cosmetic raw material supplier, Potassium Metabisulfite personal care ingredient supplier and bulk Potassium Metabisulfite ingredient supply.
Food, pharmaceutical and cosmetic specifications should only be claimed where the supplied material actually complies with the relevant standard.
| Parameter | Specification |
|---|---|
| Appearance | White or colourless crystals / white powder |
| Assay (HPLC) | NLT 90.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| Heavy Metals | NMT 10 ppm |
| Water Content | NMT 1.0% |