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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Water solubility

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Administrative data

Link to relevant study record(s)

water solubility
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
The study was conducted in accordance with OECD 105 but full details are not available.
according to guideline
OECD Guideline 105 (Water Solubility)
not specified
GLP compliance:
not specified
Type of method:
flask method
Key result
Water solubility:
> 450 g/L
20 °C
Remarks on result:
other: A pH of 10 was assumed for the test substance.
Details on results:
The substance is completely soluble in water.


Phosphorus content (g/L)

Shaking time (hr)







A measured water solubility of >450 g/L at 20°C was determined for ATMP-N-Oxide-5K using a relevant test method, the result is considered to be reliable.

Description of key information

Water solubility (ATMP-N-Oxide-5K): The substance is very soluble in water and has a water solubility value of >450 g/L at 20°C

Key value for chemical safety assessment

Water solubility:
450 g/L
at the temperature of:
20 °C

Additional information

A measured water solubility of >450 g/L at 20°C was determined for the aqueous solution of ATMP-N-Oxide-5K using the flask method in accordance with OECD Test Guideline 105. The result is considered to be reliable and is selected as key study. Although the supplier's literature is less detailed than laboratory study reports, given the range of values expected for these types of substance, the uncertainty is not significant in respect of environmental exposure or human health exposure modelling. Typical concentrations of aqueous solutions in commercial supply provides weight of evidence of high loadings.

Supporting water solubilities of 560, 490 g/L and 'soluble in water' were obtained for the potassium salt of ATMP-N-Oxide from supplier's data.

Phosphonate salts are highly hydrophilic and extremely water soluble. Free acids are less soluble than the salts; however, aqueous solutions in excess of 1% active acid material can be prepared. The aqueous solutions of sodium and potassium salts are miscible in water.