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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2008-02-25 to 2008-04-29
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
Remarks:
The testing facility indicated that the protocol was followed without deviation.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Remarks:
The testing facility indicated that the protocol was followed without deviation.
GLP compliance:
yes (incl. certificate)
Remarks:
The Department of Health of the Government of the United Kingdom
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products: Sample solutions were taken for analysis at various times.
- Sampling method: Duplicate aliquots of sample solution were diluted by a factor of 20 using methanol.
- Sampling methods for the volatile compounds, if any: not aplicable
- Sampling intervals/times for pH measurements: Sample solutions were taken for analysis at various times.
- Sampling intervals/times for sterility check: no data
- Sample storage conditions before analysis: The solutions were shielded from light and maintained at 50.0 ± 0.5 deg C for a period of 240, 120 and 120 hours respectively
Buffers:
- pH: 4, 7, and 9
- Type and final molarity of buffer:
* pH4: Potassium hydrogen phthalate (0.05 mols per cubic decimeter)
* pH 7: disodium hydrogen orthophosphate (anhydrous) (0.03 mols per cubic decimeter), Potassium dihydrogen orthophosphate (0.02 mols per cubic decimeter), Sodium chloride (0.02 mols per cubic decimeter)
* pH9: Disodium tetraborate (0.01 mols per cubic decimeter), Sodium chloride (0.02 mols per cubic decimeter)
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: The test solutions were split into individual vessels for each data point.
- Sterilisation method: The buffer solutions were filtered through a 0.2 µm membrane filter to ensure they were sterile before commencement of the test.
- Lighting: none
- Measures taken to avoid photolytic effects: The solutions were shielded from light whilst maintained at the test temperature.
- Measures to exclude oxygen: The buffer solutions were subjected to ultrasonication and degassing with nitrogen to minimize dissolved oxygen content.
- Details on test procedure for unstable compounds: not applicable
- Details of traps for volatile, if any: not applicable
- If no traps were used, is the test system closed/open: no data
- Is there any indication of the test material adsorbing to the walls of the test apparatus?: no data

TEST MEDIUM
- Preparation of test medium: Sample solutions were prepared in glass flasks at a nominal concentration of 1.00 g/L in the three buffer solutions. Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 240, 120 and 120 hours respectively. The test solutions were split into individual vessels for each data point.
- Renewal of test solution: no
- Identity and concentration of co-solvent: Duplicate aliquots of sample solution were diluted by a factor of 20 using methanol

OTHER TEST CONDITIONS
- Adjustment of pH: no data
- Dissolved oxygen: no data
Duration:
240 min
pH:
4
Initial conc. measured:
0.999 g/L
Duration:
120 min
pH:
7
Initial conc. measured:
1.12 g/L
Duration:
120 min
pH:
9
Initial conc. measured:
1.08 g/L
Number of replicates:
two
Positive controls:
not specified
Negative controls:
not specified
Statistical methods:
The concentration of the sample solutions was calculated using the equation: sample concentration (g/L) = (mean peak area of sample solution/mean peak area of standard solution, corrected to nominal standard concentration) x nominal standard concentration (50 mg/L) x sample dilution factor (20) x 1/1000
Preliminary study:
no data
Test performance:
The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 100 mg/L. This was satisfactory with a correlation coefficient of 1.000 being obtained for each of the pH 4, pH 7 and pH 9 analysis matrices.
Transformation products:
not measured
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: Less than 10% hydrolysis after 5 days at 50 deg C.
Key result
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: Less than 10% hydrolysis after 5 days at 50 deg C.
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: Less than 10% hydrolysis after 5 days at 50 deg C.

No peaks at the approximate retention time of the test material were detected on the analysis of any matrix blank. An additional peak at approximately 9.5 minutes in the pH 4 analysis matrix was attributed to the phthalate content of the buffer solution and was observed in the relevant matrix blanks also. There was a minor drop in the pH 4 sample concentration of approximately 10% during the first 24 hours of testing; but critically no significant further decrease in concentration occurred during the following 216 hours at 50.0 ± 0.5 °C. Therefore, as a reduction of only 0.67% was determined between the 24 hour and the 240 hour time points, the test material was concluded to be hydrolytically stable. This was since less than 10% hydrolysis was observed over a time period exceeding 5 days at 50 °C, equivalent to a half-life greater than 1 year at 25 °C.

Validity criteria fulfilled:
yes
Conclusions:
According to OECD 111, T002675 was found to be hydrolitically stable at pH 4.0, 7.0 and 9.0 with an estimated half-life time higher than 1 year at 25°C. Therefore, no further testing was performed. The results of the test can be considered reliable without restriction.

Description of key information

One study (O'Connor, 2008) was performed according to OECD guideline 111 and regarded as key study (Klimisch score of 1). A half-life time of > 1 year at 25°C and pH 4.0, 7.0 and 9.0 was determined for T002675.

Key value for chemical safety assessment

Additional information