Naphthenic acids, lithium salts

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04 September 2017 - 04 November 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

27 July 1995

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

30 May 2008

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Specific details on test material used for the study:

- Source and lot/batch No.of test material: A065/99
- Expiration date of the lot/batch: 1st July 2019
- Purity: UVCB

Key result

Remarks on result:

not determinable

Details on results:

Sample number 1 (10 g/L loading rate) remained visibly saturated with a dispersion of excess, undissolved test item even after centrifugation and filtration. Although sample number 2 (1.0 g/L loading rate) and sample number 3 (0.1 g/L loading rate) solutions were visibly clear and colorless after centrifugation, the supernatants still presented a strong Tyndall beam, indicating light scattering originating from a dispersion of emulsified, excess, undissolved material remaining suspended in the solution. On filtration of the supernatants through a 0.2 μm filter, the Tyndall beam response remained in the resulting filtrate, indicating a colloidal nature to the dispersion.

The behaviour of the test item in an aqueous environment was as expected, based on its chemical structure and composition. The significant surface-active properties presented by the test item resulted in the formation of a colloidal (< 0.2 μm) dispersion of excess, undissolved test item throughout the saturated solution. As this dispersed, excess, undissolved material could not be satisfactorily removed by either centrifugation of filtration techniques, it was not possible to isolate a genuine saturated aqueous solution of test item suitable for analysis and quantification.

An additional preliminary evaluation sample was also prepared on instruction by the Study Director, but has not been presented in this report. This was since this sample was not evaluated over a sufficient time period to be relevant to the regulatory methods for the determination of water solubility.

Conclusions:

No determination of water solubility was feasible for the test item.

Executive summary:

Envigo (2018) is a GLP-compliant study following OECD guideline 105 and is considered reliable without restrictions (Klimisch 1). A flask method was used to determine water solubility. No determination of water solubility was feasible for the test item. This was due to the test item, representative of the chemical class of anionic surfactants, showing significant surface-active properties in an aqueous environment. When attempting to generate saturated solutions, a colloidal suspension (i.e. containing micelles < 0.2 µm) was formed. As this dispersed, excess, undissolved material could not be satisfactorily removed by either centrifugation of filtration techniques, it was not possible to isolate a genuine saturated aqueous solution of test item suitable for analysis and quantification. 

 

Description of key information

No determination of water solubility was feasible for the test item.

Additional information

Envigo (2018) is a GLP-compliant study following OECD guideline 105 and is considered reliable without restrictions (Klimisch 1). A flask method was used to determine water solubility. No determination of water solubility was feasible for the test item. This was due to the test item, representative of the chemical class of anionic surfactants, showing significant surface-active properties in an aqueous environment. When attempting to generate saturated solutions, a colloidal suspension (i.e. containing micelles < 0.2 µm) was formed. As this dispersed, excess, undissolved material could not be satisfactorily removed by either centrifugation of filtration techniques, it was not possible to isolate a genuine saturated aqueous solution of test item suitable for analysis and quantification.

As lithium naphthenate is a UVCB consisting of a large number of different constituents, water solubility values have been predicted for representative structures within the UVCB. The QSAR model WATERNT v 1.01 was used and the study was assigned a reliability score of 2 (Reliable with restrictions) as it is an accepted calculated method. The water solubility predictions of the representative constituents of lithium naphthenate are in the range of 3.1 E-07 to 1887.6 mg/L

As lithium naphthenate is a UVCB consisting of a large number of different constituents, water solubility values have been predicted for representative structures within the UVCB. The QSAR model WSKOWWIN v 1.42 was used and the study was assigned a reliability score of 2 (Reliable with restrictions) as it is an accepted calculated method. The water solubility predictions of the representative constituents of lithium naphthenate are in the range of 9.367 E-07 to 5.141 E+05 mg/L.