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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
Study period:
24.2.-3.3.2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable guideline study, tested with the source substance Ethyl centralite. According to the ECHA guidance “Practical guide 6" the reliability was changed to RL2 to reflect the fact that this study was conducted on a read-across substance.
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
See attached document in IUCLID Section 13 - RA Justification document.pdf

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See attached document in IUCLID Section 13 - RA Justification document.pdf

3. ANALOGUE APPROACH JUSTIFICATION
See attached document in IUCLID Section 13 - RA Justification document.pdf

4. DATA MATRIX
See attached document in IUCLID Section 13 - RA Justification document.pdf, Table 1: Data matrix
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Sample storage conditions before analysis: The volumetric flasks were placed in the thermostatic bath kept at a certain temperature. The body of each flask was wrapped in an aluminium foil and tightly closed with a stopper. At certain period of time, a portion of sample solution was transferred into a vial followed by a quick cooling to room temperature.
Buffers:
Buffered solutions were prepared in accordance with the Method C.7 – Degradation – Abiotic Degradation: Hydrolysis as a Function of pH, Council Regulation (EC) No 440/2008, Appendix 3: Buffer Systems – Clark and Lubs:
- Buffer pH 4.0 - pH 3.97 (22.4°C)
- Buffer pH 7.0 - pH 7.12 (22.4°C)
- Buffer pH 9.0 - pH 8.96 (22.4°C)

Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: volumetric flask, the body of each flask was wrapped in an aluminium foil and tightly closed
- Sterilisation method: all glassware, reagent-grade water and buffer solutions were sterilised by autoclave (121°C, 50 min)

TEST MEDIUM
- Kind and purity of water: deionized water

CALIBRATION SOLUTION
– Approx. 500 mg of test substance was dissolved and diluted with MeOH into a 100mL volumetric flask (CSS). This stock solution was diluted to 2 concentrations.
– Calibration Stock Solution 1 (CSS I): 10mL of CSS was pipetted into 100mL volumetric flask and the flask was filled up to the volume with MeOH.
– Calibration Stock Solution 2 (CSS II): 2mL of CSS was pipetted into 100mL volumetric flask and the flask was filled up to the volume with MeOH.
The stock solutions CSS I and CSS II were diluted with appropriate solvent to 5 more concentrations of calibration solutions.

SAMPLE SOLUTION
0.5 mL CSS I / 50 mL appropriate buffered solution of given pH (4.0, 7.1, and 9.0)

Duration:
5.1 d
pH:
3.83
Temp.:
50 °C
Duration:
5.1 d
pH:
7.07
Temp.:
50 °C
Duration:
5.1 d
pH:
8.88
Temp.:
50 °C
Number of replicates:
2 replicates
Positive controls:
no
Negative controls:
no
Preliminary study:
The preliminary test has shown that the test substance was rather stable at any of given pH of buffered solutions, i.e. 4.0, 7.1, and 9.0, during the whole period of 5 days.
Transformation products:
no
% Recovery:
> 90
pH:
3.83
Temp.:
50 °C
Duration:
5.1 d
% Recovery:
> 90
pH:
7.07
Temp.:
50 °C
Duration:
5.1 d
% Recovery:
> 90
pH:
8.88
Temp.:
50 °C
Duration:
5.1 d
Key result
pH:
3.83
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
7.07
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
8.88
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Details on results:
TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes
Validity criteria fulfilled:
yes
Conclusions:
The preliminary test has shown that the test substance was rather stable at any of given pH of buffered solutions, i.e. 4.0, 7.1, and 9.0, during the whole period of 5 days.
The test substance is considered hydrolytically stable (t0.5, 25°C > 1 year) therefore no additional testing (Tier 2, Tier 3) is required.
Executive summary:

The procedure was performed according to Method C.7 – Degradation – Abiotic Degradation: Hydrolysis as a Function of pH, Council regulation (EC) No 440/2008. Published in OJ No L 142/518 May 2008.

The preliminary test has shown that the test substance was rather stable at any of given pH of buffered solutions, i.e. 4.0, 7.1, and 9.0, during the whole period of 5 days.

The test substance is considered hydrolytically stable (t0.5, 25°C > 1 year) therefore no additional testing (Tier 2, Tier 3) is required.

Description of key information

The preliminary test has shown that the read-across test substance Ethyl centralite was rather stable at any of given pH of buffered solutions, i.e. 4.0, 7.1, and 9.0, during the whole period of 5 days.

The test substance is considered hydrolytically stable (t0.5, 25°C > 1 year) therefore no additional testing (Tier 2, Tier 3) is required.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 yr
at the temperature of:
25 °C

Additional information