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Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
31 October 2017- 01 March 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide
EC Number:
253-021-4
EC Name:
2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide
Cas Number:
36411-52-6
Molecular formula:
C9H8N4O2
IUPAC Name:
2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide
Test material form:
solid: particulate/powder
Details on test material:
Batch:102Z5
Purity: 99.9%
white powder
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
- Sampling intervals/times for pH measurements: Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 120 hours for pH 4 and pH7, and 1152 hours for pH 9.
Duplicate sample solutions were taken initially and from the waterbath at various time points. The pH of each solution recorded. The concentration of test item in the sample solutions was determined by high performance liquid chromatography (HPLC).
Buffers:
- pH: 4, 7, 9
- Type and final molarity of buffer:
Citric acid 6mmol dm-3,
Sodium chloride 4mmol dm-3,
Sodium hydroxide 7mmol dm-3,
Disodium hydrogen orthophosphate (anhydrous) 3mmol dm-3,
Potassium dihydrogen orthophosphate 2mmol dm-3,
Sodium chloride 2mmol dm-3,
Disodium tetraborate 1mmol dm-3,
Sodium chloride 2mmol dm-3,
Details on test conditions:
Stock solutions of test item were prepared at a nominal concentration of 1 mg/L in the three buffer solutions. A 1% co-solvent of acetonitrile:dimethylformamide (95:5 v/v) was used to aid solubility. The stock solutions were split into individual glass vessels, sealed with minimal headspace, for each data point. These sample solutions were shielded from light whilst maintained at the test temperature.
Duration of testopen allclose all
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
ca. 0.001 g/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
ca. 0.001 g/L
Duration:
1 152 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
ca. 0.001 g/L
Number of replicates:
duplicate
Positive controls:
not specified
Negative controls:
not specified
Statistical methods:
not specified

Results and discussion

Transformation products:
no
Total recovery of test substance (in %)open allclose all
% Recovery:
ca. 105
pH:
4
Temp.:
50 °C
Duration:
ca. 120 h
% Recovery:
ca. 104
pH:
7
Temp.:
50 °C
Duration:
ca. 120 h
% Recovery:
43.9
pH:
9
Temp.:
50 °C
Duration:
ca. 1 152 h
Dissipation DT50 of parent compoundopen allclose all
Key result
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified
Key result
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified
Key result
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified
Details on results:
The results at the 192 hours’ time point were higher than the initial concentration; the reason for this was unknown. The samples for the 1152 hours’ time point were re-sampled and all re-analysed as confirmation due to the difference in the results for the first analysis. No significant peaks were observed at the approximate retention time of the test item on analysis of any matrix blank solutions.
If hydrolysis had been occurring and continued at a similar rate observed up to 120 hours, then essentially no Test Item should have been remaining in the time points at 1032 and 1152 hours. This assumed that hydrolysis would be pseudo-first order. The guidelines state that a substance is considered stable to hydrolysis if there is less than a 10% decrease in 120 hours. Therefore, in a 1080 hour time period (9 x 120 hours) this equates to a decrease of 61% at the same rate. As the results at 1152 hours suggested no more than 61% of the test item had been lost, then it can be concluded that the test item does not hydrolyse more than 10% in 120 hours and can be considered stable to hydrolysis at pH 9. Even so, there was a loss of Test Item for which the reason was not confirmed but it may have been due to oxidation which is typically not pseudo-first order due to the concentrations of dissolved oxygen being a limiting factor.
Results with reference substance:
n/a

Applicant's summary and conclusion

Validity criteria fulfilled:
no
Conclusions:
The half-life at 25 °C of the test item was shown to be greater than 1 year at pH 4, pH 7 and pH 9. However, it was considered that degradation of the test item observed at pH 9 was not due to hydrolysis but may have been due to oxidation; although this wasn’t proven.

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