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Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 February 2011 – 04May 2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study has been performed according to OECD and EC guidelines and in compliance with GLP principles.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011
Report date:
2011

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Version / remarks:
(2004)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Version / remarks:
(Official Journal of the European Union no. L142, May 31, 2008)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): E-BW102
- Description: Reddish brown powder
- Batch: MB-1
- Test substance storage: At room temperature protected from light
- Stability under storage conditions: Stable
- Expiry date: 23 December 2015
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
The concentration of the test substance in the test samples was determined immediately after preparation (t=0) and after 5 days. The samples taken at t=5 days were cooled to room temperature using running tap water. The samples were diluted by a factor of 100 with water to
obtain concentrations into the calibration range and analysed.

Blank buffer solutions were treated similarly as the test samples and analysed at t=0.

The pH of each of the test solutions (except for the blanks) was determined at each sampling time.
Buffers:
- pH: 4
- Type and final molarity of buffer: Acetate buffer, 0.1 M
- Composition of buffer: solution of 16.6% 0.1 M sodium acetate and 83.4% 0.1 M acetic acid. The buffer contains 0.0009% (w/v) sodium azide.

- pH: 7
- Type and final molarity of buffer: Phosphate buffer, 0.1 M
- Composition of buffer: solution of 0.1 M potassium dihydrogenphosphate adjusted to pH 7 using 10 N sodium hydroxide. The buffer contains
0.0009% (w/v) sodium azide.

- pH: 9
- Type and final molarity of buffer: Borate buffer, 0.1 M
- Composition of buffer: solution of 0.1 M boric acid and 0.1 M potassium chloride adjusted to pH 9 using 10 N sodium hydroxide. The buffer
contains 0.0009% (w/v) sodium azide.
Details on test conditions:
All solutions containing the test substance were protected from light.

Test substance solutions were prepared in the buffer solutions at a target concentration of 100 mg/l. Each solution was filter-sterilised through a 0.2 μm FP 30/0.2 CA-S filter (Whatman, Dassel, Germany) and transferred into a sterile vessel. To exclude oxygen, nitrogen gas was purged through the solution for 5 minutes. For each sampling time, duplicate sterile vessels under vacuum were filled with 6 ml test solution and placed in the dark in a temperature controlled environment at 50.0°C +/- 0.2°C.
Duration of testopen allclose all
Duration:
5 d
pH:
4
Initial conc. measured:
130 - 133 mg/L
Duration:
5 d
pH:
7
Initial conc. measured:
147 mg/L
Duration:
5 d
pH:
9
Initial conc. measured:
123 - 124 mg/L
Number of replicates:
2 measurements at each pH (separate vessels)

Results and discussion

Preliminary study:
At pH 4, pH 7 and pH 9 a degree of hydrolysis of < 10% was observed after 5 days. It demonstrated that the half-life time of the test substance at 25°C is > 1 year. According to the guideline, no further tests were required.

No test substance was detected in the blank buffer solutions.
Test performance:
The mean recoveries in buffer solutions at pH 4 and pH 9 fell within the acceptable range for nonlabelled chemicals of 70-110%. It demonstrated that the analytical method was adequate to support the hydrolysis study on the test substance.
The mean recovery in buffer solution pH 7 was slightly higher than the criterion 70-110% (112%). This was still considered acceptable.
Total recovery of test substance (in %)open allclose all
% Recovery:
106 - 108
pH:
4
Temp.:
50 °C
% Recovery:
112 - 113
pH:
7
Temp.:
50 °C
% Recovery:
104 - 105
pH:
9
Temp.:
50 °C

Any other information on results incl. tables

Preliminary test – hydrolysis of the test substance at pH 4, pH 7 and pH 9

pH code

Sampling time

Analysed concentration
[mg/l]

Degree of hydrolysis
[%]

Actual pH

Individual

Mean

 

 

 

 

 

 

pH 4

0 hours

130

 

 

4.0

 

 

133

 

 

4.0

 

5 days

133

- 1.1

- 3.9

4.0

 

 

140

- 6.6

 

4.0

 

 

 

 

 

 

pH 7

0 hours

147

 

 

7.1

 

 

147

 

 

7.1

 

5 days

143

2.7

2.0

7.1

 

 

145

1.3

 

7.1

 

 

 

 

 

 

pH 9

0 hours

123

 

 

9.0

 

 

124

 

 

9.0

 

5 days

133

- 8.0

- 6.3

9.0

 

 

129

- 4.6

 

9.0

 

 

 

 

 

 

Applicant's summary and conclusion

Conclusions:
The preliminary test (Tier 1) was performed for the determination of the rate of hydrolysis of E-BW102 at pH values normally found in the environment (pH 4-9).

At each pH value a degree of hydrolysis of < 10% was observed after 5 days. According to the guideline, performance of the main study (Tier 2) was not required.

From the results it was concluded that the half-life times of E-BW102 at 25°C are > 1 year at pH4, pH7 and pH9.