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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-10-26 to 2017-10-31
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Version / remarks:
April 13, 2004
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Version / remarks:
Official Journal of the European Union L 142; May 31, 2008
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products: 0 and 120 h
- Sampling method: -
- Sampling intervals/times for pH measurements: 0 and 120 h
- Other observation: none
Buffers:
Buffer solutions at pH 4.0, 7.0 and 9.0 were prepared.
pH 4.0: 76.5 mL 0.1 M Sodium acetate and 423.5 mL 0.1 M Acetic acid were mixed
pH 7.0: 250 mL 0.1 M TRIS buffer and 233 mL 0.1 M Hydrochloric acid were diluted to 500 mL with ultra-pure water
pH 9.0: 53.5 mL 0.2 M Sodium hydroxide and 125 mL 0.2 M Boric acid and Potassium chloride were diluted to 500 mL with ultra-pure water
Details on test conditions:
TEST SYSTEM
- Material: glass
- Type, volume of headspace: 20 mL headspace vials
- Is there any indication of the test material adsorbing to the walls of the test apparatus? none
TEST MEDIUM
- Volume used/treatment: 20 mL
- Kind and purity of water: ultra-pure sterile water
- Preparation of test medium: 250 mg dissolved in each buffer solution to a total volume of 250 mL
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
0.99 µg/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
0.99 µg/L
Duration:
120 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.95 µg/L
Number of replicates:
5 per pH
Positive controls:
no
Negative controls:
yes
Preliminary study:
Recovery after 120 h at 50 °C:
- pH 4: 105%
- pH 7: 95%
- pH 9: 96%
Therefore, it was concluded that the substance is hydrolytically stable and no further experiments were conducted.
Transformation products:
not measured
% Recovery:
105
pH:
4
Temp.:
50 °C
Duration:
120 h
Remarks on result:
hydrolytically stable based on preliminary test
% Recovery:
95
pH:
7
Temp.:
50 °C
Duration:
120 h
Remarks on result:
hydrolytically stable based on preliminary test
% Recovery:
96
pH:
9
Temp.:
50 °C
Duration:
120 h
Remarks on result:
hydrolytically stable based on preliminary test
Key result
Remarks on result:
hydrolytically stable based on preliminary test
Details on results:
The hydrolysis test was performed at 50 ± 0.5 °C, at pH 4, 7 and 9. Measured concentrations and pH values are summarised in the table in the section “Any other information on results incl. table”



Table 5: Measured data

















































































































































































pH



Sampling
time, hour



Concentration of BIS-TRIS



Measured pH



Results of the replicates in m/mL



Mean,


mg/mL



Measured


Nominal. %



End/Start



4



0


(Start)



Control buffers



-



-



3.96



0.99



0.99



99



-



4.21



0.99



0.97



0.99



1.00



120



Control buffers



-



-



4.11



1.36*



1.03



103



105



4.21



1.02



1.04



1.04



1.04



7



0


(Start)



Control buffers



-



-



7.00



0.99



0.99



98



-



7.47



0.96



0.99|



1.00



1.00



120



Control buffers



-



-



7.02



0.97



0.93



93



95



7.52



0.90



0.94



0.92



0.94



9



0


(Start)



Control buffers



-



-



S.9S



0.95



0.95



94



-



9.00



0.93



0.95



0.96



0.95



120



Control buffers



-



-



9.08



0.92



0.91



90



96



9.01



0.91



0.91



0.91



0 9C





*Wrong dilution; this value was not taken into consideration for further calculations.

Validity criteria fulfilled:
yes
Conclusions:
The hydrolysis of the substance as a function of pH was determined in a preliminary test according to OECD Test Guideline 111 under GLP conditions.
As no hydrolysis was observed at pH 4, 7 and 9 at 50 °C for 120 h, it was concluded that the substance is hydrolytically stable and the hydrolysis was not investigated further.
Executive summary:





The hydrolysis of the test item in solutions of three different pH values at 50 ± 0.5 °C was evaluated according to OECD Guideline No. 111, ”Hydrolysis as a Function of pH” and Council Regulation (EC) No. 440/2008, Part C, C.7, "Degradation - Abiotic Degradation: Hydrolysis as a Function of pH”. During the course of this study, a preliminary test was carried out. There was a slight increase in the pH value at the start of the experiment at pH 4 (actual value: pH 4.21) and pH 7 (actual value: 7.47). From the start onwards the pH was stable and the variation was not more than 0.1 pH units until the end of the measurement as it was noted for the other measurement at pH 9. These small differences were considered to have no effect on the outcome of the study in the absence of any indication for degradation at the actual values. It is considered that the test item would have been stable also at pH values of 4.0 and 7.0. Therefore, this study is considered valid and no repetition of the experiment was necessary. No hydrolysis was observed at pH 4, pH 7 and pH 9 at temperature 50 °C after 120-hours, thus, it was concluded that the substance is hydrolytically stable and the hydrolysis was not investigated further.

Description of key information



The hydrolysis of the substance as a function of pH was determined in a preliminary test according to OECD Test Guideline 111 under GLP conditions.


As no hydrolysis was observed at pH 4, 7 and 9 at 50 °C for 120 h, it was concluded that the substance is hydrolytically stable and the hydrolysis was not investigated further (reference 5.1.2-1).

Key value for chemical safety assessment

Additional information


The hydrolysis of the test item in solutions of three different pH values at 50 ± 0.5 °C was evaluated according to OECD Guideline No. 111, ”Hydrolysis as a Function of pH” and Council Regulation (EC) No. 440/2008, Part C, C.7, "Degradation - Abiotic Degradation: Hydrolysis as a Function of pH”. During the course of this study, a preliminary test was carried out. There was a slight increase in the pH value at the start of the experiment at pH 4 (actual value: pH 4.21) and pH 7 (actual value: 7.47). From the start onwards the pH was stable and the variation was not more than 0.1 pH units until the end of the measurement as it was noted for the other measurement at pH 9. These small differences were considered to have no effect on the outcome of the study in the absence of any indication for degradation at the actual values. It is considered that the test item would have been stable also at pH values of 4.0 and 7.0. Therefore, this study is considered valid and no repetition of the experiment was necessary. No hydrolysis was observed at pH 4, pH 7 and pH 9 at temperature 50 °C after 120-hours, thus, it was concluded that the substance is hydrolytically stable and the hydrolysis was not investigated further.