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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15.08.2016-24.08.2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Buffers:
The hydrolysis of test substance was examined at buffered solutions of selected pH value: 4, 7 and 9. The actual pH value at given temperature was measured using a calibrated pH meter. All prepared buffer solutions were sterilized in a pressure cooker for 50 min and purged by nitrogen. -Buffer pH 4.0-pH 4.04, (24.1°C)-Buffer pH 7.0-pH 6.94 (24.1°C)-Buffer pH 9.0-pH 8.92 (24.1°C)Preparation of mobile phases:A: Approximately 0.39 g of CH3COONH4 was dissolved in 1L of deionized H2O. B: 50 mL of deionized H2O and 950 mL of MeOH were mixed.
Details on test conditions:
TTEST SYSTEM- Type, material and volume of test flasks, other equipment used: volumetric flask wrapped with an aluminum foil and tightly closed with a stopper.- Sterilisation method: All glassware, reagent-grade water and buffer solutions were sterilized in an autoclave (121 °C, 50 min).TEST MEDIUM- Kind and purity of water: deonized waterCALIBRATION SOLUTIONSStock Solution (SS, 10 000 mg/L): ): Approximately 50 mg of Direct Blue 78 was weighed into a 50 mL volumetric flask, dissolved in and diluted to volume with deionized H2O.SAMPLE SOLUTIONS4.19 mL of (1000 mg/L) standard solution were pipetted into a 50mL volumetric flask and diluted with a buffered solution of certain pH (4, 7, or 9) – in duplicate. A nominal concentration of 80 mg/L Direct Blue 78 was prepared. Each buffered sample solution was bubbled with nitrogen for at least 5 min. The sample solutions in volumetric flasks were wrapped with an aluminum foil and tightly closed with a stopper. During the experimental part of hydrolysis, the volumetric flasks were placed in the thermostatic bath kept at a given temperature. At certain period of time, a portion of sample solution was transferred into a vial followed by a quick cooling to room temperature.
Duration:
5.05 d
pH:
3.95
Temp.:
50 °C
Duration:
5.05 d
pH:
6.97
Temp.:
50 °C
Duration:
5.05 d
pH:
8.95
Temp.:
50 °C
Number of replicates:
2
Positive controls:
no
Negative controls:
no
Preliminary study:
The preliminary test was performed at 50 °C over the period of 5 days. All glassware, reagent-grade water and buffer solutions were sterilized in a pressure cooker for 50 min. The actual pH value of each buffered solution is given in Table 2. There was no observation of degradation greater than 10 % in all buffered solutions over period of 5 days. Test substance was considered to be stable at all tested pH values (Table 3).
Transformation products:
no
% Recovery:
-1.3
pH:
3.95
Temp.:
50 °C
Duration:
5.05 d
Remarks on result:
hydrolytically stable based on preliminary test
% Recovery:
-4.7
pH:
6.97
Temp.:
50 °C
Duration:
5.05 d
Remarks on result:
hydrolytically stable based on preliminary test
% Recovery:
-4.8
pH:
8.92
Temp.:
50 °C
Duration:
5.05 d
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
3.95
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
6.97
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
8.92
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
hydrolytically stable based on preliminary test

Table2:pH values of buffersolutions

pH at room temperature

pH at 50 °C

4.04

3.95

6.94

6.97

8.92

8.95

Table3:Results of preliminary test

pH 3.95 at 50 °C

pH 6.97 at 50 °C

pH 8.95 at 50 °C

Days

Hydrolysis

(%)

Days

Hydrolysis

(%)

Days

Hydrolysis

(%)

0.00

0.0

0.00

0.0

0.00

0.0

3.11

-0.6

3.11

-1.7

3.11

-1.7

4.19

-1.0

4.19

-2.9

4.19

-2.7

5.05

-1.3

5.05

-4.7

5.05

-4.8

Validity criteria fulfilled:
yes
Conclusions:
The preliminary test has shown that the test substance was not hydrolyzed by more than 10% in period of 5 days at pH 4, 7 and 9. Therefore the test substance was considered to be hydrolytically stable at above pHs. It can be assumed that the half-time at 25 °C would be > 1 year.
Executive summary:

The procedure was performed according to: Method C.7 – Degradation – Abiotic Degradation: Hydrolysis as a Function of pH, Council regulation (EC) No 440/2008. Published in OJ No L 142/518 May 2008 and OECD Test Guidline No.111, Hydrolysis as a function of pH, Adopted April 13, 2004.

 

The preliminary test has shown that the test substance was not hydrolyzed by more than 10% in period of 5 days at pH 4, 7 and 9. Therefore the test substance was considered to be hydrolytically stable at above pHs. It can be assumed that the half-time at 25 °C would be > 1 year.

Description of key information

Test was performed according to the Method C.7 – Degradation – Abiotic Degradation: Hydrolysis as a Function of pH, Council regulation (EC) No 440/2008. Published in OJ No L 142/518 May 2008 and OECD Test Guidline No.111, Hydrolysis as a function of pH, Adopted April 13, 2004.

Only one study is available.

GLP study.

Klimish score 1.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 yr
at the temperature of:
25 °C

Additional information