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Environmental fate & pathways

Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
not specified
Remarks:
According to REACH (1907/2006), Annex VIII, Column 2, 9.2.2.1., the study does not need to be conducted if the substance is biodegradable. The GLP requirement is therefore considered not to be relevant.
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products:
- Sampling method: After a certain incubation time, incubation vessels were removed from the water bath and analyzed immediately following sampling, whenever possible.
- Sampling methods for the volatile compounds, if any:
- Sampling intervals/times for pH measurements:
- Sampling intervals/times for sterility check:
- Sample storage conditions before analysis:
- Other observation, if any (e.g.: precipitation, color change etc.):
Buffers:
pH 4: 50 mM citric acid-citrate-buffer
pH 7: 50 mM phosphoric acid-phosphate-buffer
pH 9: 50 mM boric acid-borate-buffer
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: Disposable glass tubes with PTFE-cap; 16 mm x 125 mm
- Sterilisation method: To minimize the risk of microbial degradation during incubation, buffer solutions as well as the incubation vessels were autoclaved. A sterility test was not performed.

STOCK SOLUTION:
552.7 mg of test substance were filled up with acetonitrile to give a total volume of 25 ml. Resulting concentration: 22.11 mg/ml.

INCUBATION SOLUTIONS
The incubation solutions were prepared by dilution of the test substance stock solution with buffer. lnto each of three 500 ml volumetric flasks, 5 ml of the etst substance stock solution were given and were filled up with sterile buffer solution (pH 4, 7 and 9) to give a final volume of 500 ml. The
concentration of the test substance in each flask was 221 mg/L, corresponding to half of the saturation concentration in water. The flasks were shaken intensively for approx. 5 min.
10 ml of incubation solution were transferred into tightly closable incubation vessels with a total volume of approx. 14 ml. For each incubation solution (pH 4, 7 and 9), 20 vessels were prepared. As every time point was analyzed in duplicate, 20 vessels correspond to a maximum of 10 time
points per pH value. Each vessel was labeled unique with temperature, pH and vial number as well as a and b respectively for separation of the duplicates. The vessels of incubation time zero were analyzed immediately after preparation without prior incubation. The definite sampling intervals for
all vessels can be found in the raw data.
Duration:
7 d
pH:
4
Temp.:
50 °C
Duration:
7 d
pH:
7
Temp.:
50 °C
Duration:
7 d
pH:
9
Temp.:
50 °C
Preliminary study:
After 7 days, at each pH value approx. 5 % of the test substance was hydrolyzed. Thus, the test substance can be considered stable to hydrolysis at pH 4, 7 and 9 and at 50°C. Furthermore, the conduct of a full hydrolysis study was considered inappropriate in relation to the results.
Calculated half-lives are:
pH 4: 97 days
pH 7: 77 days
pH 9: 84 days
As the decline of the test substance concentration in the buffer solutions is quite small in relation the variability of the analytical method, the determined half-lives should be judged as approximations.
Transformation products:
no
pH:
4
Temp.:
50 °C
DT50:
ca. 97 d
Type:
not specified
Remarks on result:
hydrolytically stable based on preliminary test
pH:
7
Temp.:
50 °C
DT50:
ca. 77 d
Type:
not specified
Remarks on result:
hydrolytically stable based on preliminary test
pH:
9
Temp.:
50 °C
DT50:
ca. 84 d
Type:
not specified
Remarks on result:
hydrolytically stable based on preliminary test
Validity criteria fulfilled:
yes
Conclusions:
After 7 days, at each pH value approx. 5 % of the test substance was hydrolyzed. Thus, the test substance can be considered stable to hydrolysis at pH 4, 7 and 9 and at 50°C. Furthermore, the conduct of a full hydrolysis study was considered inappropriate in relation to the results.

Description of key information

Validated QSAR model suitable for this substance type.

Key value for chemical safety assessment

Additional information

A preliminary study according to OECD 111 has been conducted to investigate the hydrolysis of the test substance at 50°C and at a pH value of 4, 7 and 9 (TAOH 2010). After 7 days, at each pH value approx. 5 % of the test substance was hydrolyzed. Thus, the test substance can be considered stable to hydrolysis at pH 4, 7 and 9 and at 50°C. A conduction of a full hydrolysis study was considered inappropriate in relation to the results.

However, according to Annex VIII (9.2.2.1, column 2) of REACH regulation the study doesn't need to be conducted because the substance is readily biodegradable.