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Hydrolysis

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Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
15 March 2012-19 June 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Remarks:
The test procedure was well described in the study report, based on the EC, OECD and OPPTS hydrolysis test guidelines and performed according to GLP principles.
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Version / remarks:
(2008)
Deviations:
yes
Remarks:
a test based on the guideline was performed
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Version / remarks:
(2004)
Deviations:
yes
Remarks:
a test based on the guideline was performed
Qualifier:
according to
Guideline:
EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)
Version / remarks:
(2008)
Deviations:
yes
Remarks:
a test based on the guideline was performed
Principles of method if other than guideline:
Quick hydrolysis of the substance was expected. To confirm this, the following test was performed instead of the tests outlined in the test guidelines. 5 ml of the test substance was mixed with 10 and 25 ml of each buffer (pH 4, 7 and 9) in a glass vessel. Each vessel was inverted 10 times by hand and the phases were allowed to separate. 4 minutes and 1 hour after preparation, a sample was taken from the upper organic phase and analysed. Chromatograms of the pretreated samples were compared with a chromatogram of untreated test substance. The test was performed at room temperature.
GLP compliance:
yes
Radiolabelling:
no
Analytical monitoring:
no
Details on sampling:
All test samples were analysed by single injection.

Buffers:
Acetate buffer pH 4, 0.1 M: solution of 16.7% (v/v) 0.1 M sodium acetate and 83.3% (v/v) 0.1 M acetic acid. The buffer contains 0.0009% (w/v) sodium azide.

Phosphate buffer pH 7, 0.1 M: 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.

Borate buffer pH 9, 0.1 M: 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.

Preliminary study:
Several small and large peaks were observed in the chromatogram of the test substance solution. It was assumed that the large peaks derive from the major components of the test substance, whereas the small peaks derive from impurities. The peak area of the major components with a retention time between 5.5 and 6.5 minutes was used as response in the calculations.

Table  Test substance response at pH 4, pH 7 and pH 9

 

Date of analysis
[dd-mm-yy]

Volume buffer solution

[ml]

pH code

Sampling time

[minutes]

response

[area]

Relative concentration
[%]

 

 

 

 

 

 

15-03-12

10

pH 4

n.a.

5483201

 

 

 

 

4

31017

0.57

 

 

 

60

75758

1.4

 

 

 

 

 

 

21-03-12

10

pH 7

n.a.

187320621

 

 

 

 

4

2522

0.01

 

 

 

60

0

0.00

 

 

 

 

 

 

21-03-12

10

pH 9

n.a.

187320621

 

 

 

 

4

7335141

39

 

 

 

60

11049995

59

 

 

 

 

 

 

15-03-12

25

pH 4

n.a.

5483201

 

 

 

 

4

0

0.00

 

 

 

60

1152

0.02

 

 

 

 

 

 

21-03-12

25

pH 7

n.a.

187320621

 

 

 

 

4

0

0.00

 

 

 

60

0

0.00

 

 

 

 

 

 

21-03-12

25

pH 9

n.a.

187320621

 

 

 

 

4

266090

1.4

 

 

 

60

102510

0.55

 

 

 

 

 

 

n.a.  not applicable; response of untreated test substance

1  average of two measurements; individual peak areas were 17681703 and 19782420

 

Validity criteria fulfilled:
not applicable
Conclusions:
The substance is hydrolytically unstable. The half-life was determined to be < 4 min at pH 4, 7 and 9.


Executive summary:

A screening test based on EC C.7, OECD 111, EPA OPPTS 830.2120 guidelines and performed under GLP, showed that the substance hydrolysis very fast at room temperature and pH 4, 7 and 9 (half-life time < 4 minutes).

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Conducted with the hydrolysis product MPKO.
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
not specified
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
not specified
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
The test substance was spiked to each of the buffer solutions at a nominal concentration of approximately 50 mg/L using a spike solution in water. For the test at pH 4, the peak areas of the test substance were determined immediately after preparation (t = 0) and at several sampling points after t = 0. The pH of the test samples was determined at the beginning and the end of the test. For the test at pH 7, the samples were prepared and placed in water baths at the end of the working day. The pH of the test samples was determined at the beginning and the end of the test.
Buffers:
Buffers: Acetate buffer pH 4: solution of 16.6 % 0.05 M sodium acetate and 83.4% 0.05 M acetic acid Phosphate buffer pH 7: solution of 0.05 M potassium di-hydrogenphosphate adjusted to pH 7 using 1 N sodium hydroxide Borate buffer pH 9: solution of 0.05 M boric acid and 0.05 M potassium chloride adjusted to pH 9 using 1 N sodium hydroxide
Duration:
120 h
pH:
7
Duration:
120 h
pH:
4
Preliminary study:
At pH 9, a decrease in concentration < 10% was observed after 120 hours. It demonstrate that the half-life time of the substance at 25 ºC > 1 year. According to the guideline, no further tests were required. At pH 4 and pH 7, a decrease in concentration > 10% after 120 hours was observed, and the main test was required. In order to determined reaction rate at 50 ºC, additional samples were taken at t= 261, 264 and 268 hours. After 268 hours of testing at 50 ºC, the relative concentration was still above 50%.
Key result
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Key result
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Key result
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Details on results:
At the end of the tests, concentrations became stable at 50-60% of the initial concentration. This shows that equilibrium if formed and that this is not hydrolysis. The test substance was determined to be hydrolytically stable (i.e. half-life time of > 1 year at 35 ºC) at pH 4, 7 and 9.
Validity criteria fulfilled:
yes
Conclusions:
MPKO is considered hydrolytically stable (i.e. half-life time of > 1 year at 25°C) at pH 4, pH 7 and pH 9.
Executive summary:

The hydrolysis test was performed in accordance with OECD Guideline 111 and EU Method C.7. In all tests performed, a decrease in concentration was observed. At the end of the main tests, concentrations became stable at 50 -60% of the initial concentration. This indicates that equilibrium is formed and that this is not hydrolysis. MPKO is therefore considered hydrolytically stable (i.e. half-life time of > 1 year at 25°C) at pH 4, pH 7 and pH 9.

Endpoint:
hydrolysis
Data waiving:
study technically not feasible
Justification for data waiving:
other:
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
Considering the extremely short lifetime of the test substance in aqueous solutions (half-life times < 4 minutes at room temperature and pH 4, 7 and 9 were measured: see supporting study), it is analytically not feasible to determine an accurate value for the half-lifetime. In accordance with REACH Annex XI, hydrolysis testing may be omitted if it is technically not possible to conduct the study.
Reason / purpose:
data waiving: supporting information

Description of key information

The half-life time of the test substance at room temperature were determined to be < 4 minutes at pH 4, 7 and 9.

A hydrolysis test was also performed on MPKO, the hydrolytic product of OS2600. MPKO was considered to be hydrolytically stable (i.e. half-life time of > 1 year at 25°C) at pH 4, pH 7 and pH 9.

Key value for chemical safety assessment

Half-life for hydrolysis:
4 min
at the temperature of:
20 °C

Additional information

Data waiving: Considering the extremely short lifetime of the test substance in aqueous solutions (half-life times < 4 minutes at room temperature and pH 4, 7 and 9 were measured: see supporting study), it is analytically not feasible to determine an accurate value for the half-lifetime. In accordance with REACH Annex XI, hydrolysis testing may be omitted if it is technically not possible to conduct the study.

Supporting study: A screening test based on EC C.7, OECD 111, EPA OPPTS 830.2120 guidelines and performed under GLP, showed that the substance hydrolysis very fast at room temperature and pH 4, 7 and 9 (half-life time < 4 minutes).

Supporting study: The hydrolysis test was performed with the analogue substance MPKO in accordance with OECD Guideline 111 and EU Method C.7 (GLP study). In all tests performed, a decrease in concentration was observed. At the end of the main tests, concentrations became stable at 50 -60% of the initial concentration. This indicates that equilibrium is formed and that this is not hydrolysis. MPKO is therefore considered hydrolytically stable (i.e. half-life time of > 1 year at 25°C) at pH 4, pH 7 and pH 9.