Sodium Salts of (1-Hydroxyethylidene)bisphosphonic acid (1-2:1)

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Qualifier:

no guideline followed

Principles of method if other than guideline:

The typically achievable solubility is inferred from the concentration of commercial aqueous solution products.

GLP compliance:

no

Type of method:

other:

Water solubility:

ca. 19 - ca. 21 other: %w/w

Conc. based on:

test mat.

Temp.:

25 °C

pH:

ca. 2.3 - ca. 2.9

Remarks on result:

other: The commercial availability of aqueous solutions of HEDP (1-2Na) salt demonstrates the possiblity to prepare stable aqueous solutions up to this concentration.

Conclusions:

The commercial availability of aqueous solutions of the salt at approximately 19-21% w/w solution concentrations demostrates that the solubility must be at least 20% w/w.

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

no guideline followed

Principles of method if other than guideline:

No information on guideline used is reported.

GLP compliance:

no

Remarks on result:

other: Disodium salt 7414-83-7 is freely soluble in water

Reference 3

Endpoint:

water solubility

Type of information:

other:

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Water solubility:

250 g/L

Temp.:

20 °C

pH:

ca. 5

Details on results:

pH Concentration: 10 g/l at 20 °C

Description of key information

Water solubility: Commercially available HEDP (1-2Na) in the form of aqueous solution products at typically approx 20% w/w are miscible in water. Furthermore the commercial availability of aqueous solutions at this typical concentration shows that HEDP (1-2Na) salt is soluble up to at least 20% w/w. The disodium salt of HEDP is 'freely soluble' in water based on a standard chemical data handbook.

Key value for chemical safety assessment

Water solubility:

200 g/L

at the temperature of:

25 °C

Additional information

In support of the Key data, it is notable that in general, 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 parent acid (HEDP-H) substance was reported as very soluble in water with a concentration of 69% at 20°C but it is not clear from the source report whether this is expressed as %w/w, %v/v or %w/v. Since the solution density is much higher than 1, the equivalent water solubility in g/L using density and concentration is reported as ≥690 g/L. In addition, as the value is known to be extremely high, the exact value is considered not significant for the chemical safety assessment for human health or environment and this limit value is therefore sufficient and is considered to be reliable.

 

A measured water solubility of 774 g/L at 20°C for the tetrasodium salt of HEDP is available.

A water solubility value of 680 g/L was reported in secondary literature for HEDP acid. The original reference was not available for review and no further information is available. The reliability of this result is not assignable and has been assigned to be supporting study.