Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12 December 2012 - 18 February 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study carried out to international guidelines and to GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline
Details on test material:
- Name of test material (as cited in study report): HMX
- Substance type: Organic
- Physical state: Solid
- Analytical purity: 99.9%
- Purity test date: no data
- Lot/batch No.: 12184
- Expiration date of the lot/batch: 31 December 2012
- Stability under test conditions: no data
- Storage condition of test material: Room temperature
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products: 0, 2, 4, 72, 120 preliminary tests
- Sampling method: 2 samples removed and 1 mL of each diluted to volume (10 mL) with acetonitrile:water (50/50, v/v)
- Sampling methods for the volatile compounds, if any:
- Sampling intervals/times for pH measurements: initial, final
- Sampling intervals/times for sterility check:
- Sample storage conditions before analysis:
- Other observation, if any (e.g.: precipitation, color change etc.):
Buffers:
- pH:
- Type and final molarity of buffer: pH 4, pH 7 and pH 9
- Composition of buffer:
pH 4: 0.2M aqueous KH2PO4 + 0.07 M aqueous disodium hydrogen orthophosphate dodecahydrate (adjusted with orthophosphoric acid)

pH 7: 0.2M aqueous KH2PO4 + 1 M sodium hydroxide (adjusted with 1M NaOH)

pH 9: 0.1M boric acid in 0.1M aqueous KCl + 1M sodium hydroxide

Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: Wheaton vials
- Sterilisation method:
- Lighting: procedure carried out in the dark
- Measures taken to avoid photolytic effects:
- Measures to exclude oxygen: purged with Nitrogen
- Details on test procedure for unstable compounds:
- Details of traps for volatile, if any
- If no traps were used, is the test system closed/open
- Is there any indication of the test material adsorbing to the walls of the test apparatus?
TEST MEDIUM
- Volume used/treatment 10 mL buffer solution
- Kind and purity of water:
- Preparation of test medium:
- Renewal of test solution:
- Identity and concentration of co-solvent:
OTHER TEST CONDITIONS
- Adjustment of pH: No
- Dissolved oxygen: No
Duration of testopen allclose all
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
2.3 mg/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
2.3 mg/L
Duration:
120 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
2.3 mg/L
Duration:
504 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
2.499 mg/L
Duration:
211 h
pH:
9
Temp.:
60 °C
Initial conc. measured:
2.338 mg/L
Duration:
71 h
pH:
9
Temp.:
70 °C
Initial conc. measured:
2.427 mg/L
Number of replicates:
2 per sampling point

Results and discussion

Preliminary study:
At pH 4 and pH 7 at 50 ± 0.5ºC less than 10% hydrolysis had occurred after 120 hours (5 days), equivalent ot an environmental (25ºC) half-life of greater than 1 year. No further testing was therefore necessary at these pH values.
At pH 9 and 50 ± 0.5ºC, however, more than 10% hydrolysis had occurred after 120 hours
(5 days), indicating a te½ value of less than 1 year. This necessitated proceeding to definitive testing at this pH value.
Test performance:
At pH 9, definitive tests were conducted at temperatures of 50, 60 and 70ºC and the hydrolysis rate constant (k) and te½ at 25ºC were extrapolated
from the measured values of log10k at the selected temperatures using the Arrhenius relationship. A te½ value of greater than 1 year was, thus, also subsequently obtained at this pH value.
There were no significant changes in pH with time.
Transformation products:
not specified

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Conclusions:
An abiotic degradation study was undertaken to evaluate the hydrolysis of HMX as a function of pH. A preliminary study was carried out at pH 4,7 and 9 at 50ºC. Further work was carried out at pH 9 at 50, 60 and 70ºC. From the results, HMX was determined to be hydrolytically stable under acidic,
neutral and basic conditions.