Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02/12/2008 to 17/02/2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP in accordance with recognised guideline

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report Date:
2009

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
yes
Remarks:
As the test material was determined to be hydrolytically stable under acidic conditions (t1/2 > 1 year at 25°C), no additional testing was performed at pH 1.2, 37.0 ± 0.5°C.
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable.
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
Two sample vessels were taken from the waterbath at each time-point, and the pH of each solution recorded. The concentration of the sample solution was determined by high performance liquid chromatography (HPLC) (see below). An aliquot of each sample solution was analysed without any further treatment. Duplicate standard solutions of test material were prepared in the respective buffer solution at a nominal concentration of 500 mg/l.
Buffers:
Buffer solution pH 4: Citric acid - 0.06 mol dm-3
Sodium chloride - 0.04 mol dm-3
Sodium hydroxide - 0.07 mol dm-3
Buffer solution pH 7: Disodium hydrogen orthophosphate (anhydrous) - 0.03 mol dm-3
Potassium dihydrogen orthophosphate - 0.02 mol dm-3
Sodium chloride - 0.02 mol dm-3
Buffer solution pH 9: Disodium tetraborate - 0.01 mol dm-3
Sodium chloride - 0.02 mol dm-3

The buffer solutions were filtered through a 0.2 µm membrane filter to ensure they were sterile before commencement of the test. Also these solutions were subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen content.
Estimation method (if used):
nda
Details on test conditions:
Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 0.5 g/l in the three buffer solutions. The test solutions were split into individual vessels for each data point. The solutions were shielded from light whilst maintained at the test temperature.

Sample solutions at pH 4 and 7 were maintained at 50.0 ± 0.5°C for a period of at least 120 hours. Sample solutions at pH 9 were maintained at 50.0 ± 0.5°C for a period of 168 hours.
Duration of testopen allclose all
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
0.5 - 0.506 g/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
0.494 - 0.498 g/L
Duration:
168 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.51 - 0.518 g/L
Number of replicates:
Two for each time and pH.
Positive controls:
yes
Remarks:
Analytical standards
Negative controls:
yes
Remarks:
Matrix blanks of respective buffer solution
Statistical methods:
Cspl = (Pspl/Pstd) x Cstd x D x 1/1000

Cspl = sample concentration (g/l)
Pspl = mean peak area of sample solution
Pstd = mean peak area of standard solution, corrected to nominal standard concentration
Cstd = nominal standard concentration (500 mg/l)
D = sample dilution factor (1)

Results and discussion

Preliminary study:
Sample solutions at pH 4 and 7 were maintained at 50.0 ± 0.5°C for a period of at least 120 hours. Sample solutions at pH 9 were maintained at 50.0 ± 0.5°C for a period of 168 hours.

The estimated half-lives at 25°C of the test material are shown in the following table

pH Estimated half-life at 25°C
4 > 1 year
7 > 1 year
9 > 1 year
Test performance:
No significant peaks were observed at the approximate retention time of the test material on analysis of any matrix blank solutions.
As the test material was determined to be hydrolytically stable under acidic conditions (t1/2 > 1 year at 25°C), no additional testing was performed at pH 1.2, 37.0 ± 0.5°C.
The analytical method was based on a method supplied by the Sponsor; the complex chromatographic profile was considered to be due to the complex nature of the test material. The large changes in chromatographic profile across the three test pH's were considered to be due to the test pH, as the profiles were consistent for the standards and samples for each test pH.
The test guideline states that the C7 test is not really applicable to mixtures. However, on review, it was decided that the chromatographic profiles for the standards were extremely similar to those for the respective samples; thus, it was considered that the results and conclusions were valid in this case.
Transformation products:
not measured
Details on hydrolysis and appearance of transformation product(s):
Recovery ranges are due to testing done in duplicate
Total recovery of test substance (in %)open allclose all
% Recovery:
101
pH:
4
Temp.:
50 °C
Duration:
120 h
% Recovery:
96.5 - 97.8
pH:
7
Temp.:
50 °C
Duration:
120 h
% Recovery:
97.5 - 98
pH:
9
Temp.:
50 °C
Duration:
168 h
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Type:
not specified
Other kinetic parameters:
no data available
Details on results:
See 'Preliminary study' above.

Any other information on results incl. tables

Duplicate standard solutions of test material were prepared in the respective buffer solution at a nominal concentration of 500 mg/l. the initial concentrations are given as a range as the testing is done in duplicate.

The test material concentrations at the given time points are shown in the following tables:

pH 4

Time (Hours) Concentration (g/l) Log10 [concentration (g/l)]

% of mean initial

concentration

A B A B A B
 
0 0.5 0.506 -0.301 -0.296 99.4 101
24* 0.425 0.426 -0.372 -0.37 84.4 84.7
48 0.503 0.509 -0.299 -0.293 99.9 101
120 0.508 0.51 -0.294 -0.292 101 101

Result:            Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-lifegreater than 1 year at 25°C.

pH 7

Time (Hours) Concentration (g/l) Log10 [concentration (g/l)] % of mean initial concentration
A B A B A B
 
0 0.498 0.494 -0.302 -0.306 100 99.6
24 0.482 0.478 -0.317 -0.321 97.2 96.2
120 0.486 0.479 -0.314 -0.32 97.8 96.5

Results:  Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-lifegreater than 1 year at 25°C.

pH 9

Time (Hours) Concentration (g/l) Log10 [concentration (g/l)] % of mean initial concentration
A B A B A B
 
0 0.51 0.518 -0.293 -0.286 99.2 101
24* 0.441 0.444 -0.355 -0.353 85.9 86.4
120 0.49 0.49 -0.31 -0.31 95.3 95.3
168 0.501 0.504 -0.3 -0.298 97.5 98

Results:  Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.

* considered to be an outlier, as out of agreement with other timepoint samples

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 1.00 x 10^3 mg/l. These were satisfactory with correlation coefficients of ≥ 0.992 being obtained
Conclusions:
The half-life of the test material was considerd to be > 1 year at pHs 4, 7 and 9.
Executive summary:

In a determination of general physico-chemical properties study (Harlan project number: 0959/0224) the test material is estimated to have a half life of greater than 1 year at pHs of 4, 7 and 9 at 25°C.

The determination was carried out using Method C7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008.

The mean total peak area of each standard was corrected to nominal concentration and the mean value taken.

The concentration of the sample solutions (g/l) was calculated using the following equation:

Cspl= (Pspl/Pstd) x Cstdx D x 1/1000

where:

Cspl= sample concentration (g/l)

Pspl= mean peak area of sample solution

Pstd= mean peak area of standard solution, corrected to nominal standard concentration

Cstd= nominal standard concentration (500 mg/l)

D = sample dilution factor (1)

The estimated half-lives at 25°C of the test material are shown in the following table:

4 >1 year

7 >1 year

9 >1 year