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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
not applicable
GLP compliance:
yes
Radiolabelling:
no
Analytical monitoring:
yes
Remarks:
High Performance Liquid Chromatography
Buffers:
- at pH value 9: borax / hydrochloric acid, Riedel de Haen Art. No. 33548, ready to use solution
- at pH value 7: potassium dihydrogen phosphate/ Di-sodium hydrogen phosphate, Riedel de Haen Art. No. 33546, ready to use solution
- at pH value 4: citric acid/ potassium hydroxide/ sodium chloride, Riedel de Haen Art. No. 33543, ready to use solution
Estimation method (if used):
Half-time and the rate constant (first order reaction) were estimated according to the Arrhenius equation.
The calculation of the half times and the reaction rate constants were based on linear regression (Inc versus t and Ink versus T 1 respectively) following the first order concentration-time-law.
Details on test conditions:
The substance was examined in each case at pH 4, 7 and 9. The test temperature was 50 °C at pH 9 and 50 °C, 60 °C. and 70 °C at pH 7 and pH 4.
Duration:
238 min
pH:
7
Temp.:
50 °C
Initial conc. measured:
100 other: %
Duration:
138 min
pH:
7
Temp.:
60 °C
Initial conc. measured:
100 other: %
Duration:
48 min
pH:
7
Temp.:
70 °C
Initial conc. measured:
100 other: %
Duration:
36 min
pH:
9
Temp.:
50 °C
Initial conc. measured:
100 other: %
Duration:
4 d
pH:
4
Temp.:
50 °C
Initial conc. measured:
100 other: %
Duration:
2 d
pH:
4
Temp.:
60 °C
Initial conc. measured:
100 other: %
Duration:
3 d
pH:
4
Temp.:
70 °C
Initial conc. measured:
100 other: %
Transformation products:
not specified
% Recovery:
68.5
pH:
4
Temp.:
50 °C
Duration:
4 d
% Recovery:
58.5
pH:
4
Temp.:
60 °C
Duration:
2 d
% Recovery:
55.8
pH:
4
Temp.:
70 °C
Duration:
3 d
% Recovery:
76.5
pH:
7
Temp.:
50 °C
Duration:
238 min
% Recovery:
59.1
pH:
7
Temp.:
60 °C
Duration:
138 min
% Recovery:
59
pH:
7
Temp.:
70 °C
Duration:
48 min
% Recovery:
14
pH:
9
Temp.:
50 °C
Duration:
36 min
pH:
4
Temp.:
50 °C
Hydrolysis rate constant:
0 s-1
DT50:
171.04 h
pH:
4
Temp.:
60 °C
Hydrolysis rate constant:
0 s-1
DT50:
57.48 h
pH:
4
Temp.:
70 °C
Hydrolysis rate constant:
0 s-1
DT50:
21.3 h
pH:
7
Temp.:
50 °C
Hydrolysis rate constant:
0 s-1
DT50:
10.3 h
pH:
7
Temp.:
60 °C
Hydrolysis rate constant:
0 s-1
DT50:
3.02 h
pH:
7
Temp.:
70 °C
Hydrolysis rate constant:
0 s-1
DT50:
1.04 h
pH:
9
Temp.:
50 °C
Hydrolysis rate constant:
0 s-1
DT50:
0.21 h
Details on results:
Half-life (t1/2) for the hydrolytic dissimilation calculated for 25 °C at different pH-values:
- at pH 7: 273 hours
- at pH 4: 3408 hours

.

At pH 9 and 50 °C a fast degradation of the test substance was observed ; within a short time (about 40 minutes), the concentration of the test substance decreased to less than 14 percent. During this time, only two analytical determinations could be performed. The degradation reaction could not be identified as a pseudo-first order reaction because only two experimental values could be evaluated.

Validity criteria fulfilled:
yes
Conclusions:
The substance is degradable at pH 9, pH 7 and pH 4. The half-lives (t1/2) for the hydrolytic dissimilation calculated for 25 ° C were 273 hours for pH 7 and 3408 hours for pH 4.
Executive summary:

The substance is degradable according to EG guideline C.7 92/69 at pH 9, pH 7 and pH 4. The calculation of the half times and the reaction rate constants were based on linear regression following the first order concentration-time-law.

The half-lives (t1/2) for the hydrolytic dissimilation calculated for 25 ° C were 273 hours for pH 7 and 3408 hours for pH 4. At pH 9 and 50 °C a fast degradation of the test substance was observed within a short time (about 40 minutes), the concentration of the test substance decreased to less than 14 percent. During this time, only two analytical determinations could be performed. The degradation reaction could not be identified as a pseudo-first order reaction because only two experimental values could be evaluated.

Description of key information

The substance is degradable according to EG guideline C.7 92/69 at pH 9, pH 7 and pH 4. The calculation of the half times and the reaction rate constants were based on linear regression following the first order concentration-time-law.

The half-lives(t1/2) for the hydrolytic dissimilation calculated for 25 ° C were 273 hours for pH 7 and 3408 hours for pH 4. At pH 9 and50 °C a fast degradation of the test substance was observed within a short time (about 40 minutes), the concentration of the test substance decreased to less than 14 percent. During this time, only two analytical determinations could be performed. The degradation reaction could not be identified as a pseudo-first order reaction because only two experimental values could be evaluated.

Key value for chemical safety assessment

Half-life for hydrolysis:
273 h
at the temperature of:
25 °C

Additional information

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