Phosphonic acid, mixed C12-20-alkyl and C14-18-unsatd. alkyl derivs.

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Between 03 November 2011 and 24 December 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Valid and conclusive guideline study under GLP

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

Commission Regulation (EC) No 440/2008 of 30 May 2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

1995

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Department of Health of Government of the U.K., inspection 19-21 July 2011

Type of method:

flask method

Water solubility:

< 0.101 mg/L

Temp.:

20 °C

pH:

>= 4.1 - <= 6.2

Remarks on result:

other: No peak detected after 24, 48 and 72 h shaking with resulting pH 6.2, 4.7 and 4.1, respectively, lowest reference standard used. 0.101 mg/L; solubility is < 0.096 mg/L considering analytical recovery of 95 %

Details on results:

The preliminary test estimate of water solubility was > 0.201 mg/L.

Table 1: Mean peak areas relating to the standard and sample solutions

Solution	Mean Peak Area
Standard 101 mg/L	49,270,000
Standard 90.6 mg/L	50,340,000
Standard 80.6 mg/L	30,480,000
Standard 70.5 mg/L	37,340,000
Standard 60.4 mg/L	18,120,000
Standard 50.4 mg/L	19'430'000
Standard 40.3 mg/L	9,964,000
Standard 30.2 mg/L	8,702,000*
Standard 20.1 mg/L	3,419,000
Standard 10.1 mg/L	1,332,000*
Matrix blanks	None detected
Samples	None detected

* These values were stated 10 times higher in the study report, which is considered erroneous, as the calibration curve, in which the mean peak area and the concentration of each standard were plotted (see illustration below) shows a picture in agreement with the figures in the table above.

As no peak was detected in the samples at the retention time of the test item, the result was based on the standard of least concentration (10.1 mg/L) which showed a definitive peak for the test item. The concentration was then corrected for the dilution by the factor 0.01.

Table 3: Concentration of test item in the sample solutions

Sample no.	Time shaken at ~ 30 ºC [h]	Time equilibrated at 20 ºC [h]	Concentration [mg/L]	Solution pH
1	24	24	< 0.101	6.2
2	48	24	< 0.101	4.7
3	72	24	< 0.101	4.1

In conclusion the overall concentration of the test item was found clearly < 0.101 mg/L at 20.0 ± 0.5 °C

Validation

Recovery of analysis of the sample procedure was assessed and proved adequate for the test. At a nominal concentration of 0.5 mg/L, a mean percentage recovery of 95.0 % was obtained (range 87.8 to 99.1 %). Concentrations have not been corrected for recovery of analysis.

Conclusions:

Interpretation of results (migrated information): insoluble (< 0.1 mg/L) considering the analytical recovery of mean 95 %
Water solubility nominal < 0.101 mg/L WAF at 20.0 ± 0.5 °C, should be regarded water insoluble (< 0.1 mg/L) considering the analytical recovery of 95 %

Executive summary:

The water solubility of the test item was investigated in a GLP-compliant study using the flask method according to the EU A.6 (2008) and OECD TG 105 (1995) protocol. The experiment is deemed valid, conclusive and thus suitable for assessment without restrictions.

Based on the preliminary result, mixtures of 0.11 g test item and 1000 mL glass double-distilled water were added to three separate flasks. Duplicate standard solutions of test item were prepared in tetrahydrofuran to cover a nominal concentration range of 10 to 100 mg/L. A calibration curve was established for the relation between the mean peak area and the standard solution test item concentration. The sample preparation assured enrichment by a factor of 100 and consequently the determination range was corrected with the dilution factor 0.01 to be 0.1 to 100 mg/L. The validation of the analytical method revealed mean 95 % recovery (range 87.8 to 99.1 %).

Based on the preliminary result, loadings of 110 mg/L glass double-distilled water were added to three separate flasks. After addition of glass double-distilled water to the flasks, they were shaken for 24, 48 or 72 h at approximately 30 °C and, after standing at 20 °C for a period of 24 h, the contents of the flasks were filtered 3 times through 0.2 µm filters. The pH of each solution was measured.

No peak was found in the watery solutions and pH 6.2, 4.7 and 4.1 were measured in the replicates shaken for 24, 48 and 72 h, respectively. Therefore it can be concluded that they contained significantly less test item than the lowest standard.

In conclusion the water solubility of the water accommodated test item was clearly < 0.101 mg/L WAF at 20.0 ± 0.5 °C, which should be regarded as water insoluble or < 0.1 mg/L considering the analytical recovery of 95 %.

Description of key information

Insoluble, nominal < 0.101 mg/L WAF at 20.0 ± 0.5 °C, should be regarded water insoluble (< 0.1 mg/L) considering the analytical recovery of 95 % (OECD 105)

Key value for chemical safety assessment

Water solubility:

0.101 mg/L

at the temperature of:

20 °C

Additional information

The water solubility was investigated in a GLP-compliant study (Fox & White 2012, Harlan Report no. 41103263) using the flask method according to the EU A.6 (2008) and OECD TG 105 (1995) protocol. The experiment is deemed valid, conclusive and thus suitable for assessment without restrictions.

No peak was found in the watery solutions. Therefore it can be concluded that they contained significantly less submission item than the lowest standard. Accordingly the water solubility of the water accommodated submission item was nominal < 0.101 mg/L WAF at 20.0 ± 0.5 °C, which can be regarded as insoluble (< 0.1 mg/L) considering mean analytical recovery of 95 %.

Despite general methodological objections a rough estimation of the actual level of water solubility may be made on the basis of the Kow, which is by definition the equilibrium concentration ratio in connected n-octanol and water phases and the water solubility. The Kow (or Pow) is > 2,510,000,000 and the water solubility is < 0.101 mg/L as derived in the respective sections. The approximation by multiplying Kow with the water solubility gives ca. 253,510,000 mg/L or ca. 253 kg/L (with increasing Kow value starting point the result increases), which seems to considerably higher than possible. This demonstrates that the water solubility is likely to be significantly lower than 0.101 mg/L by two or more orders of magnitude.