Sodium Alginate is the sodium salt of alginic acid, a naturally derived polysaccharide obtained primarily from brown seaweeds. It is a linear, unbranched copolymer consisting mainly of β-D-mannuronic acid (M) and α-L-guluronic acid (G) units linked through 1→4 glycosidic bonds. The ratio and sequence of M and G units vary according to the seaweed source and extraction process.
In cosmetic formulations, Sodium Alginate is a versatile cosmetic ingredient used for film formation, viscosity modification, binding and formulation stabilization. Its ability to dissolve in water and produce viscous colloidal solutions makes it particularly useful in aqueous skin-care and personal-care systems.
Sodium Alginate is available in different viscosity grades. Therefore, two products carrying the same INCI name can have substantially different rheological properties depending on molecular weight, M/G ratio, concentration and processing conditions.
Sodium Alginate has the INCI name SODIUM ALGINATE and CAS Number 9005-38-3. Its representative polymeric formula is (C₆H₇NaO₆)ₙ. The average structural-unit equivalent weight is approximately 222.00, while the theoretical equivalent weight is approximately 198.11.
Because Sodium Alginate is a natural polymer, it does not have one fixed molecular weight. JECFA and USP references indicate a typical average molecular-weight range of approximately 10,000–600,000 g/mol.
The M/G ratio and sequence distribution affect gel formation, viscosity and interaction with multivalent ions. In particular, calcium ions can interact strongly with alginate chains and produce gel structures, which is an important consideration for cosmetic formulation development.
Sodium Alginate is primarily valued as a film-forming, viscosity-modifying and binding cosmetic ingredient. When hydrated in water, it produces a viscous colloidal solution that can contribute body and texture to formulations.
Its film-forming characteristics make it useful in facial masks, gels and other topical formulations where a cohesive polymeric layer is desirable. It can also support the physical stability and consistency of cosmetic systems by modifying their rheological properties.
The polymer's interaction with calcium and other multivalent ions is particularly important. Controlled ionic crosslinking can create alginate gels, while uncontrolled exposure to multivalent ions may change viscosity or cause precipitation and gel formation.
Sodium Alginate can be incorporated into a wide range of skin-care and personal-care formulations. Potential applications include facial masks, peel-off mask systems, gels, creams, lotions, serums and other water-based cosmetic preparations.
It can function as a viscosity modifier in aqueous systems and as a film-forming material in formulations requiring a cohesive surface layer. It can also be combined with other polysaccharides such as Pullulan, Dextran, Beta-Glucan and Chitosan, provided compatibility is evaluated.
The appropriate viscosity grade should be selected according to the desired formulation texture. Low-, medium- and high-viscosity Sodium Alginate grades can produce substantially different processing and sensory characteristics.
Viscosity grade, molecular weight, M/G composition and hydration conditions are important when formulating with Sodium Alginate.
Current USP information specifies Sodium Alginate at 90.8–106.0% calculated on the dried basis, with typical average molecular weight of approximately 10,000–600,000 g/mol.
Indian food-additive specifications specify 91–106% purity, moisture NMT 15%, water-insoluble matter NMT 1%, minimum viscosity of 30 cP for a 1% solution, ash 18–27%, acid-insoluble ash NMT 0.5%, lead NMT 5 mg/kg and arsenic NMT 3 mg/kg. These are food-additive specifications and should not automatically be represented as a universal cosmetic specification.
Commercial grades demonstrate how viscosity can vary significantly. Documented grades include approximately 20–50 mPa·s, 100–200 mPa·s, 320–380 mPa·s and 800–900 mPa·s for 1% aqueous solutions, depending on the grade and test conditions.
The Assay (HPLC) field should not be populated with an arbitrary HPLC percentage. Sodium Alginate assay is generally defined through specific chemical procedures, while viscosity, moisture, ash and molecular-weight characteristics are important quality parameters.
Sodium Alginate is a versatile marine-derived cosmetic ingredient for manufacturers developing masks, gels, creams, lotions and other personal-care formulations. Its combination of water compatibility, film formation and rheological functionality makes it useful across several formulation formats.
For B2B cosmetic raw-material sourcing, the exact grade should be selected according to molecular weight, viscosity, M/G characteristics, moisture, ash, pH, insoluble matter, heavy metals and microbiological quality.
As a Sodium Alginate Cosmetic Ingredient Manufacturer in India, the ingredient can support bulk cosmetic raw-material and personal-care formulation requirements.
| Parameter | Specification |
|---|---|
| Appearance | White or colourless crystals / white powder |
| Assay (HPLC) | 90.8–106.0% |
| Loss on Drying | NMT 15.0% |
| Residue on Ignition | 18.0–27.0% |
| pH (1% Solution) | 5.5–8.0 |