Sodium Sulfite is an inorganic sulfur-containing cosmetic ingredient used in selected personal-care formulations for its antioxidant, reducing and preservative properties. Its INCI name is SODIUM SULFITE. The compound is identified by CAS No. 7757-83-7, has the molecular formula Na₂SO₃, and a formula weight of 126.04 g/mol. JECFA identifies Sodium Sulfite as white powder with no more than a faint sulfur-dioxide odour.
Sodium Sulfite is also known as Disodium Sulfite and is chemically different from Sodium Metabisulfite. Sodium Sulfite contains the sulfite ion, SO₃²⁻, whereas Sodium Metabisulfite contains S₂O₅²⁻. These materials therefore require separate raw-material specifications and should not be treated as interchangeable in a formulation.
Sodium Sulfite has the chemical formula Na₂SO₃ and a molecular weight of 126.04 g/mol. The material is highly soluble in water and sparingly soluble in ethanol. JECFA reports an assay of not less than 95.0%, while the USP-NF specification defines Sodium Sulfite at 95.0–100.5% Na₂SO₃.
Sodium Sulfite is susceptible to oxidation in air. USP describes its solutions as alkaline, and the Food Chemicals Codex describes the material as a white or tan to slightly pink powder.
Because it is an inorganic sulfite salt, a conventional organic-compound HPLC assay should not automatically be assigned to this ingredient. Depending on the applicable specification, assay and sulfite content may be established through validated titrimetric or instrumental methods. JECFA specifications include identification tests for sodium and sulfite and specific impurity controls.
COSMILE Europe identifies Sodium Sulfite as having several cosmetic functions, including antioxidant, fragrance functional, hair waving or straightening, preservative and reducing functions. Its reducing activity can modify the chemical structure of other substances, while its antioxidant function helps limit oxidation of formulation components.
COSMILE also notes that Sodium Sulfite is encountered as a reducing agent in hair-dye systems and permanent-wave products and as a preservative in alkaline environments.
The actual role of Sodium Sulfite should be determined by the finished formulation. Its performance depends on factors such as pH, concentration, oxidation conditions and interactions with other formulation ingredients.
Sodium Sulfite Cosmetic Ingredient can be considered for a range of formulation systems, including:
Its reducing chemistry makes it particularly relevant to hair-treatment systems in which controlled chemical reduction is required. COSMILE specifically identifies its use in hair waving or straightening and as a reducing ingredient.
Sodium Sulfite should be evaluated carefully according to the formulation's pH and intended function. JECFA specifies a pH of 8.5–10.0 for a 1-in-10 solution, while its specification also controls thiosulfate and metal impurities.
Sodium Sulfite can undergo oxidation in air, so storage and packaging conditions should be appropriate for maintaining raw-material quality. The Food Chemicals Codex notes that Sodium Sulfite undergoes oxidation in air.
For commercial quality control, important parameters include identification, Sodium Sulfite assay, pH, thiosulfate, iron, lead and other applicable elemental impurities. Since the material is an inorganic salt, the SDP CMS should not contain an invented HPLC assay value.
Sodium Sulfite is a specialty cosmetic ingredient and raw material used in selected antioxidant, reducing and personal-care formulation systems. Companies sourcing Sodium Sulfite in India may require defined purity, sulfite content, pH, impurity limits and batch-level quality documentation.
For B2B procurement, relevant searches include Sodium Sulfite cosmetic ingredient manufacturer in India, Sodium Sulfite supplier India, Sodium Sulfite manufacturing in India, Sodium Sulfite cosmetic raw material supplier, Sodium Sulfite personal care ingredient supplier and bulk Sodium Sulfite ingredient supply.
The exact commercial grade should be selected according to the intended application and market requirements. Cosmetic, food and pharmaceutical specifications should only be claimed where the supplied material actually meets the respective standard.
| Parameter | Specification |
|---|---|
| Appearance | White or colourless crystals / white powder |