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Environmental fate & pathways

Hydrolysis

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Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Cross-reference
Reason / purpose:
read-across source
Reference
Endpoint:
hydrolysis
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
It is considered appropriate to address the hydrolysis data requirement for fatty acids, C12-20 and C12-20 unsatd., 2-ethylhexyl esters by applying read-across from available data on the epoxidised oil ETP (a UVCB substance), given that both substances are of similar chemical structure, being long- chain esters with 2-ethyl hexanol. A read-across justification document is attached in section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Transformation products:
not specified
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
pH:
9
Temp.:
25 °C
DT50:
>= 1 yr

No further information.

Validity criteria fulfilled:
yes
Conclusions:
The estimated half-life at 25 degC of the test material at different pH values is:
pH 4: > 1 year
pH 7: > 1 year
pH 9: approximately ≥ 1 year
In a further assessment at a physiological important pH and temperature (pH 1.2, 37degC), 85.1% of the test material was found to remain after 24 hours.
Executive summary:

It is considered appropriate to address the hydrolysis data requirement for fatty acids, C12-20 and C12-20 unsatd., 2-ethylhexyl esters by applying read-across from available data on the epoxidised oil ETP, given that both substances are of similar chemical structure, being long- chain esters with 2-ethyl hexanol.

Based on read-across from ETP, the estimated half-life of at 25°C of C12-20 and C12-20 unsatd., 2-ethylhexyl esters is >1 year.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
Pale yellow liquid.
Batch number: 39395
Storage conditions: room temperature, in the dark.
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 1.40 x 10-3 g/l in the three buffer solutions. A 1% co-solvent of tetrahydrofuran was used to aid solubility. The solutions were shielded from light whilst maintained at the test temperature.
Buffers:
pH 1.2: Hydrochloric acid 0.0645 mol/dm3 and potassium chloride 0.05 mol/dm3.
pH 4: Potassium hydrogen phthalate 0.0025 mol/dm3
pH 7: Disodium hydrogen onhophosphate (anhydrous) 0.0015 mol/dm3, Potassium diidrogen orthophosphate 0.0010 mol/dm3 and sodium chloride 0.0010 mol/dm3
pH 9: Disodium tetraborate 0.0005 mol/dm3 and sodium chloride 0.0010 mol/dm3

The buffer solutions were filtered through a 0.2 µm membrane filter to ensure they were sterile before commencement of the test. Also these solutions were subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen content.
Statistical methods:
Not stated

Results and discussion

Preliminary study:
Sample solutions at pH 4 and 7 were maintained at 50.0 +/- 0.5°C for a period of 120 hours. The sample solution at pH 9 was maintained at 50.0 +/- 0.5°C for a period of 168 hours.
Test performance:
A further assessment at a physiological important pH and temperature (pH 1.2, 37°C) was also performed for a period of 24 hours.
Transformation products:
not specified
Details on hydrolysis and appearance of transformation product(s):
No details provided.
Total recovery of test substance (in %)open allclose all
% Recovery:
>= 137 - <= 147
pH:
4
% Recovery:
>= 88.6 - <= 90.3
pH:
7
% Recovery:
>= 99.1 - <= 106
pH:
9
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
pH:
9
Temp.:
25 °C
DT50:
>= 1 yr
Other kinetic parameters:
No further details.
Details on results:
In the pH 9 test, the amount of test material remaining after 120 hours dropped below 90%.
Therefore, a further sample was taken at 168 hours for comparison purposes. This sample showed that the concentration had increased slightly. This variation is considered to be due to the analytical method required for this test material. There was approximately 7% variation in recovery at pH 9 which would have taken percentages remaining back up to 90%. Additionally, Gel Permeation Chromatography is not ideally suited to hydrolysis assessment as it is a largely qualitative and not quantitative technique. The hydrolysis test is also essentially designed for pure, single component materials and as such, applying this material to the test procedures is difficult. Therefore, considering the nature of the material, and the method of analysis used, the results have been considered acceptable and valid.
A higher percentage recovery was observed at pH 4. This was possibly due to some background interference from buffer solutions or an effect of pH specific to the GPC column or analysis method. However, since the test material did not hydrolyse and was found to be stable. this was considered negligible.

Any other information on results incl. tables

No further information.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The estimated half-life at 25 degC of the test material at different pH values is:
pH 4: > 1 year
pH 7: > 1 year
pH 9: approximately ≥ 1 year
In a further assessment at a physiological important pH and temperature (pH 1.2, 37degC), 85.1% of the test material was found to remain after 24 hours.
Executive summary:

The estimated half-life at 25 degC of the test material at different pH values is:

pH 4: > 1 year

pH 7: > 1 year

pH 9: approximately ≥ 1 year

In a further assessment at a physiological important pH and temperature (pH 1.2, 37degC), 85.1% of the test material was found to remain after 24 hours.