Characteristic

 

Tetrasodium pyrophosphate, also called sodium pyrophosphate, tetrasodium phosphate or TSPP, is an inorganic compound with the formula Na₄P₂O₇. As a salt, it is a white, water-soluble solid. It is composed of pyrophosphate anion and sodium ions.

Chemical formula:H₂₀Na₄O₁₇P₂

Molar mass: 446.06 g/mol

Appearance: Colorless or white crystals

Odor: odorless

Density: 2.534 g/cm³

Melting point: 988 °C (1,810 °F; 1,261 K) (anhydrous);79.5 °C (decahydrate)

Boiling point: decomposes

Solubility in water:2.61 g/100 mL (0 °C);6.7 g/100 mL (25 °C);42.2 g/100 mL (100 °C)

Solubility: insoluble in ammonia, alcohol

Refractive index (nD):1.425

Crystal structure:monoclinic (decahydrate)

 

Application

 

Sodium pyrophosphate decahydrate is used as a buffering agent, an emulsifier, a thickening agent, a food additive and a dispersing agent. It acts as a tartar control agent in tooth paste and dental floss and is used to remove calcium and magnesium from saliva, thereby avoiding its deposition on teeth. It is utilized in detergents to prevent deposition on cloth. It is useful in the preparation of an EDTA-sodium pyrophosphate extraction buffer for microcystin analysis of soil samples. In antimicrobial studies, it is used as a chelating agent.