Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
01, 03, 08 July 2002 (experimental phase)
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline-conform study without deviations
Cross-reference
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guideline
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
Details on test material:
- Name of test material (as cited in study report): MXDA/SM ADDUCT
- Physical state: pale yellow viscous liquid
- Analytical purity: not reported
- Impurities (identity and concentrations): not reported
- Composition of test material, percentage of components: components given in the study report still were based on information retrieved from old GC analytical data (for details see chapter 1.2)
Component 1: 54.9 %
Component 2: 4.7 %
Component 3: 36.4 %
Conponent 4: 4.0 %
- Isomers composition: not reported
- Purity test date: not reported
- Lot/batch No.: PMS-02A
- Expiration date of the lot/batch: not reported
- Stability under test conditions: not reported
- Storage condition of test material: room temperature in the dark, until 12 April 2002, thereafter, room temperature, in the dark, under nitrogen

Study design

Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products: initial and after 120 minutes, transformation products were not studied
- Sampling method: not given
- Sampling intervals/times for pH measurements: initial and after 120 minutes
- Sampling intervals/times for sterility check: no sterile check was performed, but buffer solutions were filtered through 0.2 µm membrane filters prior to test solution preparation
- Sample storage conditions before analysis: no storage, samples were analysed immediately
- Other observation, if any (e.g.: precipitation, color change etc.):
Buffers:
- pH: 4
- Concentration: 1.25 E-02 mol/dm3
- Composition of buffer: potassium hydrogen phthalate

- pH: 7
- Concentration: 7.5 E-03 mol/dm3, 5 E-03 mol/dm3, 5 E-03 mol/dm
- Composition: disodium hydrogen orthophosphate (anhydrous), potassium dihydrogen orthophosphate, sodium chloride

- pH: 9
- Concentration: 2.5 E-03 mol/dm3, 5 E-03 mol/dm3
- Composition: disodium tetraborate, sodium chloride
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: stoppered glass flasks
- Sterilisation method: filtering through 0.2 µm membrane filter
- Lighting: not reported
- Measures taken to avoid photolytic effects: not reported
- Measures to exclude oxygen: degassing with nitrogen to minimise dissolved oxygen content
- Is there any indication of the test material adsorbing to the walls of the test apparatus? not reported
TEST MEDIUM
- Volume used/treatment: not reported
- Kind and purity of water: not reported
- Preparation of test medium: buffer solutions were prepared according to information given in the section on buffers
- Renewal of test solution: not applicable
- Identity and concentration of co-solvent: not applicable
OTHER TEST CONDITIONS
- Adjustment of pH: pH was adjusted to about 10.5 prior to extraction using 1.0 M sodium hydroxide solution
- Dissolved oxygen: not reported
Duration of testopen allclose all
Duration:
120 h
Initial conc. measured:
0.002 - 0.002 other: g/L, component 1
Duration:
120 h
Initial conc. measured:
0 - 0 other: g/L, component 2
Duration:
120 h
Initial conc. measured:
0.001 - 0.001 other: g/L, component 3
Duration:
120 h
Initial conc. measured:
0 - 0 other: g/L, component 4
Number of replicates:
Two replicates per pH value plus additional two standard replicates at initiation of test and after 120 hours
Positive controls:
no
Negative controls:
no
Statistical methods:
not reported

Results and discussion

Preliminary study:
Less than 10% hydrolysis after 5 days at 50 °C was observed for all substance components at pH 4, 7 or 9. A half-life of greater than 1 year at 25 °C is anticipated.
Transformation products:
not specified
Details on hydrolysis and appearance of transformation product(s):
not applicable
Total recovery of test substance (in %)open allclose all
% Recovery:
97.2 - 111
pH:
4
Temp.:
50 °C
Duration:
120 h
% Recovery:
95.1 - 107
pH:
7
Temp.:
50 °C
Duration:
120 h
% Recovery:
87.9 - 94
pH:
9
Temp.:
50 °C
Duration:
120 h
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: applicable to all 4 components of test substance
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: applicable to all 4 components of test substance
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: applicable to all 4 components of test substance

Any other information on results incl. tables

Following the analysis of the initial standard and sample solutions, due to excessive baseline drift associated with the high temperature program required to elute the test material, the instrument analysis was repeated for component 4 only using a column compensation. However, the initial component 4 concentrations remained significantly lower than anticipated based on the loading concentration and the percentage recovery obtained during validation of the analytical method. Therefore the percentage remaining after 120 hours incubation at 50.0 ± 0.5 °C has been calculated from the theoretical as weighed concentration corrected for the mean percentage recovery obtained at nominal concentrations of 5.0 and 2.5 mg/L.

Under basic conditions (pH 9) the two minor components, component 2 and 4 present at 4.7% and 4.0% respectively, were analysed as borderline to the 90% remaining hydrolytic stability cut-off value. However a half-life of greater than 1 year at 25OC was estimated based on:

i) The experimental variation in analytical concentrations were within expectations of the method accuracy for the trace levels of the two minor components.

ii) At pH 9, the potential for adsorption onto the glassware was maximised for the test material over the range investigated. This was since the reduced ionization of the test material reduced the solubility of the individual components. Secondly, under basic conditions the free silanol activity, typically the site of adsorption, was maximised.

Therefore, although the flasks used for sample solution incubation were treated with dimethyldichlorosilane to eliminate free silanol groups, some potential for limited adsorption may have remained.

Therefore based on a maximum 12.1% reduction in test material concentration, the increased percentage remaining for the more significant components and the identification of a potential source for the reduction in test material concentration, the half-life has been estimated as greater than 1 year at 25 °C.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The substance is hydrolytically stable at pH 4, 7 or 9 at a temperature of 25 °C with half-lives of greater than 1 year.
Executive summary:

The hydrolytical stability of the test substance "MXDA/SM Adduct" was determined under GLP and in accordance with EU Method C.7 in a preliminary test at pH 4, 7 and 9 at a test temperature of 50 ± 0.5 °C. Sample solutions were prepared in stoppered glass flasks at nominal concentrations of the test material of 4 E-03 g/L in three buffer solutions. Buffer solution for pH 4 contained 1.25 E-02 mol/dm3 potassium hydrogen phthalate, buffer solution for pH 7 contained 7.5 E-03 mol/dm3 disodium hydrogen orthophosphate (anhydrous), 5 E-03 mol/dm3 potassium dihydrogen orthophosphate and 5 E-03 mol/dm3 sodium chloride and buffer solution for pH 9 contained 2.5 E-03 mol/dm3 disodium tetraborate and 5 E-03 mol/dm3 sodium chloride. The buffer solutions were filtered through 0.2 µm membrane filters to ensure sterile conditions and the solutions were subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen concentrations. Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 120 hours. Aliquots of the sample solutions were taken from the flasks at various times and the pH of each solution recorded. The concentration of the sample solutions was determined by gas chromatography and the four main components of the test substance were all detected with acceptable accurateness and recovery rates. Prior to extraction each sample solution was adjusted to about pH 10.5 using 1.0 M sodium hydroxide solution. Duplicate aliquots were taken and extracted with 3 x 30 mL dichloromethane. Each extract was filtered through pre-washed separation paper, extracts were combined and evaporated to dryness. Then the residue was re-dissolved in 10 mL acetonitrile. Duplicate standard solutions at nominal concentrations of 40 mg/L were prepared and sampled and analysed in parallel to the test solutions. Less than 10% hydrolysis for compounds 1 to 3 was observed at 50 °C after 5 days suggesting that these compounds had hydrolysis half-lives of greater than 1 year at 25 °C and pH 4, 7 and 9. Analytical problems due to excessive baseline drift associated with the high temperature required to elute the test material made it necessary to re-analyse component 4 only using column compensation. However, the initial concentrations of component 4 remained significantly lower than anticipated and the percentage remaining after 120 hours hence was calculated from the theoretical as weighed concentration corrected for the mean percentage recovery at nominal concentrations of 5 and 2.5 mg/L.

Under basic conditions at pH 9, the two minor components were analysed as borderline to the cut-off value for hydrolytic stability (90% test substance remaining after 120 hours at 50 °C). However, a half-life of greater than 1 year at 25 °C was estimated for these two compounds because experimental variation in analytical concencentration was within the range expected from the method accuracy for the two trace compounds and the potential adsorption onto glassware was maximised for the test material over the range investigated. This was since the reduced ionisation of the test material reduced the solubility of the individual components and since the free silanol activity, typically the site of adsorption, was maximised under basic conditions.

In conclusion, the estimated half-life at 25 °C for all four components of the test material was greater than 1 year.