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Diss Factsheets

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
27 JUNE 2007 to 18 SEPTEMBER 2007
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
This study follows international guidelines and comply with GLP. The study design is adapted to the test substance yet no certificate of analysis was provided therefore doubts remain whether the test substance is the reference substance of the current dossier. Thus the results are deemed reliable with this last restriction.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report date:
2007

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
2-methyl-3-butenenitrile
EC Number:
240-596-1
EC Name:
2-methyl-3-butenenitrile
Cas Number:
16529-56-9
Molecular formula:
C5H7N
IUPAC Name:
2-methylbut-3-enenitrile
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products: 0h, 48h, 120h
- Sampling method: in duplicate
- Sampling methods for the volatile compounds, if any: No headspace was left in the vessel to stop volatilisation of the test material
- Sampling intervals/times for pH measurements: 0h, 48h, 120h
- Sampling intervals/times for sterility check: no data
- Sample storage conditions before analysis: shielded from light
- Other observation, if any (e.g.: precipitation, color change etc.): no data
Buffers:
pH=4 - Potassium hydrogen phtalate at 0.005M

pH=7 - Disodium hydrogen orthophosphate (anhydrous) at 0.003M - Potassium dihydrogen orthophosphate (anhydrous) at 0.002M - sodium chloride at 0.002M

pH=9 - Disodium tetraborate 0.01M - Sodium chloride 0.002M

All buffers were filtered at 0.2µm to ensure they were sterile before commencement of the test.
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used:
- Sterilisation method: 0.2 µm filtration
- Lighting: prevent for samples
- Measures taken to avoid photolytic effects: no data
- Measures to exclude oxygen: no data
- Details on test procedure for unstable compounds: not applicable
- Details of traps for volatile, if any: no data
- If no traps were used, is the test system closed/ope:n closed system with no headspace left in vessels
- Is there any indication of the test material adsorbing to the walls of the test apparatus? no

TEST MEDIUM no details

OTHER TEST CONDITIONS no details
Duration of testopen allclose all
Duration:
120 h
pH:
4
Temp.:
50
Initial conc. measured:
503 mg/L
Duration:
120 h
pH:
7
Temp.:
50
Initial conc. measured:
531 mg/L
Duration:
120 h
pH:
9
Temp.:
50
Initial conc. measured:
519 mg/L
Number of replicates:
duplicate at each time interval
Positive controls:
not specified
Negative controls:
not specified
Statistical methods:
no data

Results and discussion

Preliminary study:
A preliminary study at 50°C was performed. Since hydrolysis half-life was estimated to be over one year at pH = 4 and pH = 7, and no hydrolysis observed at pH = 9, the study was terminated.
Transformation products:
no
Details on hydrolysis and appearance of transformation product(s):
At pH = 9, at 120 h peaks of other products appeared but was assumed to be impurities since they also appeared, at lower levels, in other samples suggesting the test substance was being transformed into items already present in the test material, as impurities.
After discussion with the sponsor isomerization was assumed. So freshly 120h samples at pH=9 were prepared and analyzed by GC-MS showing those products were isomers of the test substance.
Isomerization was thus confirmed and was little observed at pH=7 but not at pH=4. It was concluded this process was base catalyzed.
Total recovery of test substance (in %)open allclose all
% Recovery:
> 99.3 - < 100
pH:
4
Temp.:
50 °C
Duration:
120 h
% Recovery:
> 97.2 - < 98.1
pH:
7
Temp.:
50 °C
Duration:
120 h
% Recovery:
> 10.8 - < 11.1
pH:
9
Temp.:
50 °C
Duration:
120 h
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
50 °C
DT50:
> 1 yr
pH:
7
Temp.:
50 °C
DT50:
> 1 yr
pH:
9
Temp.:
50 °C
Remarks on result:
other: isomerisation

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
At pH = 4 and 7 based on recovery percentage, half-life of the test substance was estimated to be over one year. At pH = 9, at 50°C it is believed that isomerization takes place but not hydrolysis.
Executive summary:

The hydrolysis as a function of pH was determined for the test substance following a GLP study according to OECD 111 guidelines. Solutions of 0.5 g/L of test substance in buffers at pH = 4, 7, and 9 were maitained at 50°C for 5 days and sampled at 0h, 48h, and 120h by gas chromatography.

At pH = 4 and 7 based on recovery percentage, half-life of the test substance was estimated to be over one year. At pH = 9, at 50°C 10.9% of the test substance was recovered. Yet after further evidence and analysis, this apparent degradation was due to base catalysed isomerization and not hydrolysis.