Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Principles of method if other than guideline:
None
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: Solid
Details on test material:
None
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
The sample solutions were taken from the waterbath at various times and the pH of each solution were recorded.
Buffers:
The test system uses sterile buffer solutions at pH’s 4.0, 7.0 and 9.0 (see below).
Estimation method (if used):
Not applicable
Details on test conditions:
Performance of the Test
Preparation of the Test Solutions
Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 1 g/L in the three buffer solutions.

The concentration of each solution did not exceed the lesser of 0.01 mol/L or half the water solubility.

The test solutions were split into individual vessels for each data point.
The solutions were shielded from light whilst maintained at the test temperature.


Preliminary Test
Sample solutions were prepared at a nominal concentration of 1 g/L at pH 4, 7 and 9 and maintained at 50.0 ± 0.5 °C for a period of 120 hours.


Tier 2
Results from the Preliminary test showed it was necessary to undertake further testing at pH 9, with solutions being maintained at 50.0 ± 0.5 °C, 60.0 ± 0.5 °C and 70.0 ± 0.5 °C for a period of 576, 288 and 144 hours respectively.
Duration of testopen allclose all
Duration:
48 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.766 - 0.796 g/L
Duration:
72 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.739 - 0.749 g/L
Duration:
168 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.488 - 0.504 g/L
Duration:
240 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.419 - 0.445 g/L
Duration:
336 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.304 - 0.31 g/L
Duration:
432 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.426 - 0.486 g/L
Duration:
576 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.378 - 0.404 g/L
Duration:
4 h
pH:
9
Temp.:
60 °C
Initial conc. measured:
0.912 - 0.954 g/L
Duration:
24 h
pH:
9
Temp.:
60 °C
Initial conc. measured:
0.719 - 0.776 g/L
Duration:
72 h
pH:
9
Temp.:
60 °C
Initial conc. measured:
0.446 - 0.45 g/L
Number of replicates:
Two
Positive controls:
no
Negative controls:
no
Statistical methods:
None

Results and discussion

Preliminary study:
Preliminary pH 4 Test at 50.0 ± 0.5 ºC
Less than 10% hydrolysis after 5 days at 50.0 ± 0.5 °C, equivalent to a half-life greater than 1 year at 25 °C.

Preliminary pH 7 Test at 50.0 ± 0.5 ºC
Less than 10% hydrolysis after 5 days at 50.0 ± 0.5 °C, equivalent to a half-life greater than 1 year at 25 °C.

Preliminary pH 9 Test at 50.0 ± 0.5 ºC
The extent of hydrolysis after 120 hours indicated that further tests (Tier 2), conducted at 50.0 ± 0.5°C, 60.0 ± 0.5°C and 70.0 ± 0.5 °C, were required to estimate the rate constant and half-life.
Test performance:
The kinetics of the study have been determined to be consistent with that of a pseudo-first order reaction as the graphs of log10 concentration versus time are straight lines.
Transformation products:
not measured
Details on hydrolysis and appearance of transformation product(s):
Not applicable
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
pH:
9
Temp.:
25 °C
Hydrolysis rate constant:
0 h-1
DT50:
222 d
Other kinetic parameters:
No data
Details on results:
pH 9 Test at 50.0 ± 0.5 ºC - Tier 2
Slope = -7.06E-04
kobs = 1.63E-03 hour-1
= 4.51E-07 second-1
t½ = 427 hours
= 17.8 days

pH 9 Test at 60.0 ± 0.5 ºC - Tier 2
Slope = -2.19E-03
kobs = 5.03E-03 hour-1
= 1.40E-06 second-1
t½ = 138 hours
= 5.74 days

pH 9 Test at 70.0 ± 0.5 ºC - Tier 2
Slope = -4.26E-03
kobs = 9.81E-03 hour-1
= 2.73E-06 second-1
t½ = 70.6 hours
= 2.94 days

pH 9 Arrhenius Data
From the graph of the data, the rate constant and half-life at 25 °C have been estimated to be as follows:
kobs = 1.30E-04 hour-1
3.61E-08 second-1
t½ = 5.34E+03 hours
= 222 days

Any other information on results incl. tables

None

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The rate constant and estimated half-life at 25 °C of the test item are:
At pH 4 the estimated half life at 25 °C was > 1 year
At pH 7 the estimated half life at 25 °C was > 1 year
At pH 9 the rate constant was 3.61E-08 s-1 at 25 °C with an estimated half life of 222 days.
Executive summary:

Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C7 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 kinetics of the study have been determined to be consistent with that of a pseudo-first order reaction as the graphs of log10 concentration versus time are straight lines.

No significant peaks were observed at the approximate retention time of the test item on analysis of any matrix blank solutions.

It has been observed that the rate of hydrolysis increases with an increase in pH.

The rate constant and estimated half-life at 25 °C of the test item are:

At pH 4 the estimated half life at 25 °C was > 1 year

At pH 7 the estimated half life at 25 °C was > 1 year

At pH 9 the rate constant was 3.61 X 10 -8 at 25 °C with an estimated half life of 222 days.