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Diss Factsheets

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 DECEMBER 1993 to 28 JULY 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study carried out according to EU testing guideline and in compliance with GLP. All presented results are reliable.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report date:
1994

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
GLP compliance:
yes
Remarks:
no certificate of analysis

Test material

Constituent 1
Chemical structure
Reference substance name:
Adiponitrile
EC Number:
203-896-3
EC Name:
Adiponitrile
Cas Number:
111-69-3
Molecular formula:
C6H8N2
IUPAC Name:
hexanedinitrile
Radiolabelling:
no

Study design

Details on sampling:
- Sampling intervals for the parent product: initially and after 21, 45, 69, 144, 192 and 234 hours
- Sampling method: no data but analysis on duplicates and purged with nitrogen prior to analysis
- Sampling times for pH measurements: monitoring over the period of the  test
- Sampling intervals/times for sterility check: no data
- Sample storage conditions before analysis: no storage of the samples
Buffers:
- pH: 4.0
- Type and final molarity of buffer: 0.05M Disodium hydrogen orthophosphate dodecahydrate and citric acid monohydrate
- Composition of buffer: Disodium hydrogen orthophosphate dodecahydrate (13.8 g) and  citric acid (6.45 g) were dissolved in purified water (950 mL) and the pH  was adjusted to 4.0 with 1M HCl or 1M NaOH. The volume was adjusted to  1000 mL with purified water.

- pH: 7.0
- Type and final molarity of buffer: 0.05M Potassium dihydrogen orthophosphate
- Composition of buffer: Potassium dihydrogen orthophosphate (3.4 g) was dissolved in  purified water (950 mL), 1 M NaOH (15 mL) was added and the pH was  adjusted to 7.0 with 1M HCl or 1M NaOH. The volume was adjusted to 1000  mL with purified water.

- pH: 9.0
- Type and final molarity of buffer: 0.05M Disodium tetraborate decahydrate and potassium dihydrogen orthophosphate
- Composition of buffer: Disodium tetraborate decahydrate (16.55 g) and Potassium  dihydrogen orthophosphate (1.80 g) were dissolved in purified water (950  mL) and the pH was adjusted to 9.0 with 1M HCl or 1M NaOH. The volume was  adjusted to 1000 mL with purified water.
Details on test conditions:
Test system:
- Type, material and volume of test flasks, other equipment used: glass  bottle (inert in the pH range studied).
- Sterilisation method: data not available.
- Lighting: in the dark.
- Measures to exclude oxygen: samples were purged with nitrogen and  sealed.
- Is there any indication of the test material adsorbing to the walls of  the test apparatus? no.

 Test medium:
- Volume used/treatment: 50 mL.
- Kind and purity of water: purified water.
- Renewal of test solution: no.
Duration of testopen allclose all
Duration:
10 d
pH:
4
Temp.:
50
Initial conc. measured:
435 - 466 mg/L
Duration:
10 d
pH:
7
Temp.:
50
Initial conc. measured:
461 - 469 mg/L
Duration:
10 d
pH:
9
Temp.:
50
Initial conc. measured:
495 - 497 mg/L
Number of replicates:
two per measured points
Positive controls:
no
Negative controls:
no
Statistical methods:
none

Results and discussion

Preliminary study:
After 10 days of experiment, plotting a regression, the back-calculation at 120 hours (5 days) at pH 4, 7 and 9 and 50°C, showed less than 10% hydrolysis had occurred, demonstrating an equivalent  half-life of greater than 1 year at all three pH values.
Transformation products:
no
Total recovery of test substance (in %)open allclose all
% Recovery:
104
pH:
4
Temp.:
50 °C
Duration:
120 h
% Recovery:
103
pH:
7
Temp.:
50 °C
Duration:
120 h
% Recovery:
96
pH:
9
Temp.:
50 °C
Duration:
120 h
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
50 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: ln Y = ln(490.8) – 3.213 x 10-4 X
pH:
7
Temp.:
50 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: ln Y = ln(462.1) + 3.538 x 10-4 X
pH:
9
Temp.:
50 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: ln Y = ln(465.0) + 2.484 x 10-4 X
Other kinetic parameters:
no data

Any other information on results incl. tables

The report mixed the lines for the total recovery results. In the current robust summary, after checking and recalculating the results, the total recovery of the test substance after 5 days are correct.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
After the preliminary experiment, half-life of the test substance appeared to be over 1 year under acid, neutral or basic conditions.
Executive summary:

The hydrolysis of the test substance was tested in a tier approach following international guidelines. The test substance was analyzed against time in duplicate by gas chromatography employing flame ionization detection under acid, neural and basic conditions. Three buffer solutions (pH = 4, 7, and 9) were used in this experiment.

After 5 days at 50 °C, more than 90% of the test substance was recovered in each buffer solutions drawing a half-life of the test substance over 1 year due to hydrolysis.