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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:
12 January 2016 to 24 February 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
GLP guideline study
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
- Physical state: yellow semi-slid
- Analytical purity: 100 %
- Expiration date of the lot/batch: 23 November 2017
- Storage condition of test material: Room temperature in the dark
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sample solutions were taken in duplicate from the water bath initially and at various times and the pH of each solution recorded.
- An aliquot of each sample was diluted by a factor of 10 to give a final matrix of methanol:purified water:buffer (5:4:1 v/v/v).
Buffers:
- Buffer solutions were subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen content.

- pH: 4
- Type and final molarity of buffer: 10 mmoL dm-3
- Composition of buffer: Sterile solution of potassium hydrogen phtalate
- Acetic acid to adjust pH: Not applicable

- pH: 7
- Type and final molarity of buffer: 10 mmoL dm-3.
- Composition of buffer: Sterile solution of disodium hydrogen orthophosphate (anhydrous), Potassium dihydrogen orthophosphate and sodium chloride.
- Sodium chloride to adjust pH: 4 mmoL dm-3

- pH: 9
- Type and final molarity of buffer: 4 mmoL dm-3.
- Composition of buffer: Sterile solution of disodium tetraborate and sodium chloride
- Sodium chloride to adjust pH: 2 mmoL dm-3
Details on test conditions:
PREPARATION OF TEST SOLUTIONS
- Stock solutions were prepared in glass flasks at a nominal concentration of 250 mg/L in the three buffer solutions with aid of sonication.
- The stock solutions were split into individual sealed glass vials (with minimal headspace) for each data point.
- The sample solutions were shielded from light whilst maintained at the test temperature.

PRELIMINARY TEST / TIER 1
- Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 120 hours.
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
0.245 g/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
0.264 g/L
Duration:
120 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.253 g/L
Number of replicates:
Two
Positive controls:
no
Negative controls:
no
Preliminary study:
- Typical chromatograms are attached.
- Mean total peak areas relating to the standard and sample solutions are shown in Table 2 (attached).
- Test item concentrations at given time points are shown in Tables 3, 4 and 5 (attached).
- The results from the preliminary Test / Tier 1 showed that it was unnecessary to undertake further testing at pH 4, 7 and 9.
Transformation products:
not measured
Key result
Remarks on result:
other: - The results from the preliminary Test / Tier 1 showed that it was unnecessary to undertake further testing at pH 4, 7 and 9.
Details on results:
- pH 4: Less than 10 % hydrolysis after 5 days at 50 °C (equivalent to a half-life greater than 1 year at 25 °C)
- pH 7: Less than 10 % hydrolysis after 5 days at 50 °C (equivalent to a half-life greater than 1 year at 25 °C)
- pH 9: Less than 10 % hydrolysis after 5 days at 50 °C (equivalent to a half-life greater than 1 year at 25 °C)
Validity criteria fulfilled:
not applicable
Conclusions:
The estimated half-life of the test item at 25 °C for pH 4, 7 and 9 has been shown to be greater than 1 year.
Executive summary:

Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C.7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004. The estimated half-life of the test item at 25 °C for pH 4, 7 and 9 has been shown to be greater than 1 year.

Description of key information

The estimated half-life of the test item at 25 °C for pH 4, 7 and 9 has been shown to be greater than 1 year.using a method compatible with OECD 111 and EU Method C.7.

Key value for chemical safety assessment

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

Additional information

Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C.7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004. The estimated half-life of the test item at 25 °C for pH 4, 7 and 9 has been shown to be greater than 1 year.