Registration Dossier

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information


Typically the purity of trisodium hydrogen diphosphate is 93% (dry weight, after excluding water).

All impurities present at >1% are other inorganic phosphates or other related inorganic substances, similar to the registered substance, and which do not significantly affect its toxicological and ecotoxicological properties. There are no hazardous impurities present within the substance at levels >0.1%.

Impurities occurring as a result of the production process are listed below.

Table 1 - Major Common Impurities in trisodium hydrogen diphosphate

Disodium dihydrogen diphosphate. EINECS: 231-835-0

< 5 %

Tetrasodium diphosphate. EINECS:231-767-1

< 5 %

Pentasodium triphosphate. EINECS: 231-838-7

< 5 %

Monosodium phosphate. EINECS: 231-449-2

< 5 %

Physico-chemical properties

Trisodium hydrogen diphosphate has a melting point of >450°C.

Trisodium hydrogen diphosphate is water soluble; 293 g/l of solution at 20.0 ± 0.5°C in un-buffered glass double-distilled water, resulting in sample solution pH’s of approximately 6.5 to 6.7.

The effect of temperature over the range 10 to 30°C has been considered not to have had a significant influence on the solubility of the test material (range 283 to 323 g/l).

The solubility of the test material over the environmentally relevant pH range of 4 to 9 gave solubility results and final solution pH’s similar to those obtained using unbuffered water (range 264 to 276 g/l). Thus, it can be anticipated that the water solubility of the test material over the pH range 4 to 9 would be constant, essentially due to the low buffering activities seen in the environment.

Trisodium hydrogen diphosphate is not considered to possess any of the following hazardous physico-chemical properties: autoflammability and/or self-ignition, flammability, explosiveness and oxidising properties.