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Sodium Tripolyphosphate (STPP)

STPP
CAS 7758-29-4 · Formula Na5O10P3 · MW 367.86 g/mol

A high-sequestering inorganic polyphosphate builder that softens water and disperses solids across detergent, ceramic, and water-treatment systems. Industry references record its use in water softening, heavy-duty fabric and automatic-dishwashing detergents, drilling-fluid treatment, and as a sequestering, dispersing, and anti-caking agent; it is also recognized as a food texturizer.

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HS Code
2835.31
At a Glance
Material Family
Acids & Salts
Record Type
Pure compound
Primary Role
Chelation / Sequestration · pH Adjustment
Solubility
Freely soluble in water. Insoluble in ethanol
Functional Roles
PENTASODIUM TRIPHOSPHATE
BUFFERINGCHELATING
Applications & Use Cases
  • Detergent builder: Softens water and boosts cleaning in fabric- and dish-washing formulations.
  • Sequestrant: Chelates calcium and magnesium ions to control water hardness and scale.
  • Dispersing agent: Peptizes and disperses solids in ceramics, pigments, and drilling fluids.
  • Food texturizer: Functions as a phosphate texturizing additive in food processing.
Physical Properties
Melting Point
622 °C
Density
2.52 g/cm³
Solubility
Freely soluble in water. Insoluble in ethanol
pH
Between 9,1 and 10,2 (1 % solution)
Safety & Handling
Full SDS available on request

A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.

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HS / Tariff Classification
Harmonized System (HS) Code — 6-digit international heading
2835 . 31
Chapter 28
Inorganic chemicals; compounds of precious metals and rare-earth metals
Heading 28.35
Internationally harmonized (WCO HS)
Subheading 2835.31
6-digit international code — national tariff line adds further digits
Chemical Identity
CAS Number
7758-29-4
Molecular Formula
Na5O10P3
Molecular Weight
367.86 g/mol
IUPAC Name
pentasodium;[oxido(phosphonatooxy)phosphoryl] phosphate
INCI Name
PENTASODIUM TRIPHOSPHATE
PubChem CID
InChI Key
HWGNBUXHKFFFIH-UHFFFAOYSA-I
Synonyms & Trade Names
Pentasodium triphosphate Armofos Thermphos Rhodiaphos LV Thermphos N Triphosphoric acid, pentasodium salt Thermphos SPR Thermphos L 50 Sodium phosphate (Na5P3O10) Sodium triphosphate (Na5P3O10) S 400 STPP SODIUM TRIPOLYPHOSPHATE, UNSPECIFIED
Full Description

Sodium tripolyphosphate (pentasodium triphosphate, CAS 7758-29-4) is an inorganic condensed phosphate. Industry references record its use in water softening, heavy-duty fabric and automatic-dishwashing detergents, drilling-fluid treatment, and as a sequestering, dispersing, and anti-caking agent; it is also recognized as a food texturizer.

Frequently Asked Questions

What is sodium tripolyphosphate (STPP) used for?

Sodium tripolyphosphate (pentasodium triphosphate, CAS 7758-29-4) is an inorganic condensed phosphate used as a detergent builder that softens water in fabric- and dishwashing formulations, as a sequestrant that chelates calcium and magnesium to control hardness and scale, as a dispersant in ceramics, pigments, and drilling fluids, and as a phosphate texturizer in food processing.

Is STPP soluble in water?

Yes. STPP is water-soluble and forms an alkaline solution; in solution it sequesters calcium and magnesium ions, which is the basis of its water-softening and anti-scale function. See the SDS for handling data.

What is the chemical formula and CAS for STPP?

Sodium tripolyphosphate has the formula Na5P3O10 and CAS 7758-29-4. It is supplied in technical and food-grade qualities; specify the grade required on your order and each lot ships with a Certificate of Analysis.

What HS code applies to sodium tripolyphosphate?

STPP is classified under HS heading 2835.31 (Sodium triphosphate / sodium tripolyphosphate). Confirm the destination tariff line with your customs broker before export.

What is the price of bulk sodium tripolyphosphate?

Bulk STPP pricing depends on grade (technical vs. food), order volume, and packaging (bags, supersacks, or bulk). Submit a bulk RFQ with quantity and delivery point and we will return a current quote with CoA and SDS.

Disclaimer. Information on this page — including properties, identifiers, hazard, transport (DOT/UN) and tariff (HS) classifications, and applications — is provided for general reference and is compiled from authoritative public sources (e.g. PubChem/ECHA, 49 CFR 172.101, the Harmonized Tariff Schedule). Values are typical and are not a guaranteed specification; the Certificate of Analysis (CoA) for the lot purchased governs. Products are sold for industrial and professional use only. Nothing here is a medical, health, or efficacy claim or advice. Always consult the current Safety Data Sheet (SDS) before handling, storage, transport or disposal, and confirm regulatory status, classification and suitability for your application and jurisdiction. Hazard, transport and tariff classifications must be verified for your specific shipment. RawSource makes no warranty, express or implied, and assumes no liability for use of this information. Trademarks. Third-party trademarks and brand names are the property of their respective owners; any reference is nominative — used only to identify a comparable product — and does not imply affiliation with, sponsorship by, or endorsement by the trademark owner.