Registration Dossier

Environmental fate & pathways

Hydrolysis

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Jan - July 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Qualifier:
according to
Guideline:
EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)
GLP compliance:
yes
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
The concentration of the test item in the test samples was determined immediately after preparation (t=0) and after 2.4 hours and 5 days. The samples taken at t=2.4 hours and t=5 days were cooled to room temperature using running tap water. Analysis was performed on subsamples of 650 μL. The samples were diluted with 350 μL of acetonitrile and analyzed.
Blank buffer solutions containing a similar content of blank spiking solution were treated similarly as the test samples and analyzed at t=0.
The pH of each of the test solutions (except for the blanks) was determined at each sampling time.
Buffers:
Acetate buffer pH 4, 0.1 M
Solution of 16.7% 0.1 M sodium acetate in water and 83.3% 0.1 M acetic acid in water. Buffer contained 0.0009% (w/v) sodium azide.
Phosphate buffer pH 7, 0.1 M
Solution of 0.1 M potassium di-hydrogenphosphate in water adjusted to pH 7 using 10N sodium hydroxide. Buffer contained 0.0009% (w/v) sodium azide.
Borate buffer pH 9, 0.1 M
Solution of 0.1 M boric acid in water and 0.01 M potassium chloride in water adjusted to pH 9 using 10N sodium hydroxide. Buffer contained 0.0009% (w/v) sodium azide.
Estimation method (if used):
The buffer solutions were filter-sterilised through a 0.2 μm FP 30/0.2 CA-S filter (Whatman, Dassel, Germany) and transferred into a sterile vessel. To exclude oxygen, nitrogen gas was purged through the solution for 5 minutes. The test item was spiked to the solutions at a target concentration of 2 mg/L using a spiking solution in dimethyl sulfoxide. For each sampling time, duplicate sterile vessels under vacuum were filled with 6 mL test solution and placed in the dark in a temperature controlled environment at 49.9°C ± 0.2°C. The spiking volume was < 1% of the sample volume. Nominal concentrations were not corrected for the spiking volume.
Details on test conditions:
Test samples were prepared and treated similarly as during the preliminary test. The concentrations of the test item were determined immediately after preparation (t=0) and at
several sampling points after t=0.
Blank buffer solutions were treated similarly as the test samples and analyzed at t=0.
The pH of each of the test solutions (except for the blanks) was determined at least at the beginning and at the end of the test.
Test Conditions Main Study
pH code Temperature I Temperature II Temperature III
pH 4 19.9°C ± 0.2°C 49.9°C ± 0.5°C 59.7°C ± 0.6°C
pH 7 19.9°C ± 0.2°C 50.0°C ± 0.4°C 59.7°C ± 0.7°C
pH 9 19.9°C ± 0.2°C 50.0°C ± 0.4°C 59.8°C ± 0.4°C
Duration:
795.07 h
pH:
4
Temp.:
20 °C
Initial conc. measured:
>= 1.93 - <= 1.96 mg/L
Duration:
792.77 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
>= 1.93 - <= 1.98 mg/L
Duration:
769.78 h
pH:
4
Temp.:
60 °C
Initial conc. measured:
>= 1.95 - <= 1.97 mg/L
Duration:
794.52 h
pH:
7
Temp.:
20 °C
Initial conc. measured:
>= 2 - <= 2.01 mg/L
Duration:
792.25 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
>= 2 - <= 2.01 mg/L
Duration:
840.93 h
pH:
7
Temp.:
60 °C
Initial conc. measured:
>= 2.01 - <= 2.02 mg/L
Duration:
793.32 h
pH:
9
Temp.:
20 °C
Initial conc. measured:
>= 1.99 - <= 2.01 mg/L
Duration:
409.97 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
>= 2.01 - <= 2.03 mg/L
Duration:
167.82 h
pH:
9
Temp.:
60 °C
Initial conc. measured:
2.01 mg/L
Number of replicates:
2
Positive controls:
no
Negative controls:
yes
Remarks:
Blank buffer solutions containing a similar content of blank spiking solution were treated similarly as the test samples and analyzed at t=0.
Statistical methods:
For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% were plotted against time. At all temperatures linear relationships were obtained.
The half-life times of the test item were determined according to the model for pseudo-first order reactions. All logarithms of the relative concentrations were correlated with time using linear regression analysis.
Preliminary study:
At pH 4, pH 7 and pH 9, a degree of hydrolysis of ≥ 10% was observed after 5 days.
Test performance:
Test samples were prepared and treated similarly as during the preliminary test. The concentrations of the test item were determined immediately after preparation (t=0) and at several sampling points after t=0.
Blank buffer solutions were treated similarly as the test samples and analyzed at t=0. The pH of each of the test solutions (except for the blanks) was determined at least at the beginning and at the end of the test.
Transformation products:
no
% Recovery:
97
pH:
4
Temp.:
20 °C
Duration:
795.07 h
% Recovery:
98
pH:
4
Temp.:
50 °C
Duration:
792.77 h
% Recovery:
98
pH:
4
Temp.:
60 °C
Duration:
769.78 h
% Recovery:
100
pH:
7
Temp.:
20 °C
Duration:
792.25 h
% Recovery:
100
pH:
7
Temp.:
60 °C
Duration:
840.93 h
% Recovery:
100
pH:
7
Temp.:
50 °C
Duration:
792.25 h
Key result
pH:
4
Temp.:
20 °C
Hydrolysis rate constant:
0 h-1
DT50:
1 210 d
Type:
(pseudo-)first order (= half-life)
Key result
pH:
4
Temp.:
50 °C
Hydrolysis rate constant:
0 h-1
DT50:
87 d
Type:
(pseudo-)first order (= half-life)
Key result
pH:
4
Temp.:
60 °C
Hydrolysis rate constant:
1.06 h-1
DT50:
27 d
Type:
(pseudo-)first order (= half-life)
Key result
pH:
7
Temp.:
25 °C
Hydrolysis rate constant:
0 h-1
DT50:
6 641 d
Type:
(pseudo-)first order (= half-life)
Key result
pH:
7
Temp.:
50 °C
Hydrolysis rate constant:
0 h-1
DT50:
290 d
Type:
(pseudo-)first order (= half-life)
Key result
pH:
7
Temp.:
60 °C
Hydrolysis rate constant:
0 h-1
DT50:
95 d
Type:
(pseudo-)first order (= half-life)
Key result
pH:
9
Temp.:
20 °C
Hydrolysis rate constant:
0 h-1
DT50:
208 d
Type:
(pseudo-)first order (= half-life)
Key result
pH:
9
Temp.:
50 °C
Hydrolysis rate constant:
0.006 h-1
DT50:
4.9 d
Type:
(pseudo-)first order (= half-life)
Key result
pH:
9
Temp.:
60 °C
Hydrolysis rate constant:
0.015 h-1
DT50:
47 h
Type:
(pseudo-)first order (= half-life)
Validity criteria fulfilled:
yes
Conclusions:
The half-life times of the test item were as follows:
pH 4 pH 7 pH 9
Temperature t½ t½ t½
[°C]
20 1210 days No hydrolysis observed 208 days
25 752 days 6641 days 106 days
50 87 days 290 days 4.9 days
60 27 days 95 days 47 hours

Description of key information

The half-life times of the test item were as follows:

                                  pH 4                            pH 7                            pH 9

Temperature                t½                                 t½                             t½

[°C]

20                            1210 days       No hydrolysis observed           208 days

25                            752 days              6641 days                            106 days

50                            87 days               290 days                            4.9 days

60                            27 days               95 days                              47 hours

Key value for chemical safety assessment

Additional information