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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Screening test 2018. Assessed over 5 days
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Justification for type of information:
Due to the nature of the UVCB substance, it was impossible to determine the precise identity of specific components and their transformation products. Instead, differences in composition resulting from dilution in water over 5 days was used to indicate that some changes were happening at a range of pH conditions.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Version / remarks:
Screening test; as it was impossible to identify specific components of the UVCB and their transformation products, a full study was not possible to perform.
Principles of method if other than guideline:
LCMS used to look for different peak characteristics after 5 days diluted in water buffered to pH 4, 7 and 9
GLP compliance:
yes
Specific details on test material used for the study:
Batch PAH225/139/5
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
Samples for analysis at time of preparation and after 5 days in water
Buffers:
pH 4 - acetic acid / sodium acetate
pH 7 - sodium hydroxide / potassium phosphate
pH 9 - sodium hydroxide / boric acid
Details on test conditions:
A volume of 100 ml was held for 5 days at 53 C
Duration:
5 d
pH:
4.55
Temp.:
53 °C
Initial conc. measured:
> 1.148 - < 1.47 g/L
Duration:
5 d
pH:
7.35
Temp.:
53 °C
Initial conc. measured:
> 1.279 - < 1.286 g/L
Duration:
5 d
pH:
9.2
Temp.:
53 °C
Initial conc. measured:
> 1.322 - < 1.388 g/L
Number of replicates:
Two replicates per pH.
Positive controls:
no
Negative controls:
no
Preliminary study:
Preliminary study identified changes in peak elution times and intensity, but specific components of the UVCB not possible to identify by these methods.
Transformation products:
not measured
Remarks:
Not possible to identify
Details on hydrolysis and appearance of transformation product(s):
The samples fully dissolved in the buffers. No changes in appearance were reported.
Key result
pH:
4
Temp.:
53 °C
Remarks on result:
not determinable because of methodological limitations
Remarks:
Specific transformation products were not possible to identify
Key result
pH:
7
Temp.:
53 °C
Remarks on result:
not determinable because of methodological limitations
Remarks:
Specific transformation products were not possible to identify
Key result
pH:
9
Temp.:
53 °C
Remarks on result:
not determinable because of methodological limitations
Remarks:
Specific transformation products were not possible to identify
Other kinetic parameters:
These were not possible to determine

Due to changes in the elution times, intensity and 'appearance' of peaks at a detection wave length of 230 nm, changes in the test material were observed over 5 days at pH 4, 7 and 9 when held at 53 C. Note that the pH ncreased under all test conditions from initial buffered pH.

The authors of the report were unable to identify any specific components and transformation products, but MS investigations following LC separation indicated that higher molecular weight components (identifed as 'polymer' in the report) were significantly reduced suggesting mechanisms such as cleavage.

Validity criteria fulfilled:
not applicable
Conclusions:
The authors of the report were unable to identify any specific components and transformation products, but MS investigations following LC separation indicated that higher molecular weight components (identified as 'polymer' in the report) were significantly reduced suggesting mechanisms such as cleavage.

It is however possible that the substance interacted with buffers, forming salts. The substance is manufactured and supplied in water and manufacture includes some hydrolysis steps with evolution of ammonia. Further hydrolysis is therefore unlikely under the conditions of pH 4, 7 and 9 and it should also be noted that the substance is used in dilute aqueous mixtures for water treatment.

Description of key information

The authors of the report were unable to identify any specific components and transformation products, but MS investigations following LC separation indicated that higher molecular weight components (identifed as 'polymer' in the report) were significantly reduced suggesting mechanisms such as cleavage.  

It is however possible that the substance interacted with buffers, forming salts.  The substance is manufactured and supplied in water and manufacture includes some hydrolysis steps with evolution of ammonia.  Further hydrolysis is therefore unlikely under the conditions of pH 4, 7 and 9 and it should also be noted that the substance is used in dilute aqueous mixtures for water treatment.

Key value for chemical safety assessment

Additional information