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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
30.07.1991 to 27.09.1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: EEC Guideline L 251/C.10 (1984)
Deviations:
no
GLP compliance:
yes
Remarks:
Swiss GLP
Specific details on test material used for the study:
- Name: FAT 40406/A
- Purity: 89.3 %
- Source and lot/batch No. of test material:
SR 6947/14
Radiolabelling:
not specified
Analytical monitoring:
yes
Details on sampling:
Three test solutions are prepared as follows:
0.1 to 0.12 g test substance is accurately weighed, dissolved in and diluted to 250.0 ml with water.
10 ml of this solution are diluted to 100 ml with the buffer solutions pH 4.0, pH 7.0, pH 9.0, respectively. Only brown volumetric flasks are used. The flasks are previously rinsed with nitrogen for 5 minutes.

After the hydrolysis period:
a) 10 ml of the test solution at pH 4 are diluted with 1.37 ml 1 N NaOH and 2.00 ml of pH 7 buffer solution.
b) The test solution at pH 7 is ready for measurement.
c) 10 ml of the test solution at pH 9 are diluted with 0.65 ml 1 N HCl and 2.00 ml of pH 7 buffer solution.
Thus producing three solutions ready for measurement. If the solutions are not immediately measured put the flask in a refrigerator.
Buffers:
pH 4: 0.1 mole acetic acid + 0.1 mole sodium acetate diluted to 1000 mL with water + 60 mL 1N HCl.
pH 7: 0.041 mole di-sodium-hydrogen phosphate+ 0.028 mole potassium di-hydrogen phosphate diluted to 1000 mL with water.
pH 9: 0.043 mole di-sodium tetraborate + 0.017 mole potassium di-hydrogen phosphate diluted to 1000 mL with water.
Estimation method (if used):
Linear regression
Details on test conditions:
Only brown volumetric flasks are used. The flasks are previously rinsed with nitrogen for 5 minutes. The hydrolysis is carried out in a thermostatically controlled water bath.
Duration:
2.4 h
pH:
4
Temp.:
50
Initial conc. measured:
0.047 g/L
Duration:
2.4 h
pH:
7
Temp.:
50
Initial conc. measured:
0.047 g/L
Duration:
2.4 h
pH:
9
Temp.:
50
Initial conc. measured:
0.047 g/L
Duration:
120 h
pH:
4
Temp.:
50
Initial conc. measured:
0.047 g/L
Duration:
120 h
pH:
7
Temp.:
50
Initial conc. measured:
0.047 g/L
Duration:
120 h
pH:
9
Temp.:
50
Initial conc. measured:
0.047 g/L
Duration:
336 h
pH:
4
Temp.:
50
Initial conc. measured:
0.047 g/L
Duration:
144 h
pH:
4
Temp.:
60
Initial conc. measured:
0.046 g/L
Duration:
72 h
pH:
4
Temp.:
70
Initial conc. measured:
0.052 g/L
Number of replicates:
2
Positive controls:
no
Negative controls:
no
Preliminary study:
Hydrolysis of the test substance at 50 °C at pH 4, 7 and 9 for the preliminary test. At 50 °C more than 10 % hydrolysis is observed only at pH 4. Therefore, the hydrolysis was further examined at pH 4. While at pH 7 and 9 the hydrolysis was observed to 0.0 %, and 3.6 %, respectively
Transformation products:
no
% Recovery:
33.4
pH:
4
Temp.:
50 °C
Duration:
336 h
% Recovery:
35.15
pH:
4
Temp.:
60 °C
Duration:
144 h
% Recovery:
32.6
pH:
4
Temp.:
70 °C
Duration:
72 h
pH:
4
Temp.:
50 °C
Hydrolysis rate constant:
0 s-1
DT50:
212.5 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: Regression equation, r² =0.9999
pH:
4
Temp.:
60 °C
Hydrolysis rate constant:
0 s-1
DT50:
95.4 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: Regression equation, r²=0.9999
pH:
4
Temp.:
70 °C
Hydrolysis rate constant:
0 s-1
DT50:
44.8 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: Regression equation, r²=0.9999
pH:
7
Temp.:
50 °C
DT50:
> 1 yr
Type:
not specified
Remarks on result:
hydrolytically stable based on preliminary test
pH:
9
Temp.:
50 °C
DT50:
> 1 yr
Type:
not specified
Remarks on result:
hydrolytically stable based on preliminary test
Other kinetic parameters:
The hydrolysis rate at pH 4 and temperature 25 °C was calculated to be: k = 0.00000009621/s and half life period: t1/2=2000.7 h.
Details on results:
The test substance has a half life period longer than one year at 25 °C and pH 7 and 9.
The test substance has a half life period of 2000.7 h at 25 °C and pH 4.
Validity criteria fulfilled:
yes
Conclusions:
FAT 40406/A has a half-life period at pH 4 and temperature 25 °C of 2000.7 h. Half-life period for pH 7 and 9 at 25 °C is over a year.
Executive summary:

In a GLP-compliant hydrolysis study conducted according to OECD Guideline 111 and EEC Guideline L 251/C.10 (1984), hydrolysis of the test substance was tested at varying temperatures and as a function of pH. A preliminary test was conducted at 50 °C at pH 4, 7 and 9 after 2.4 and 120 hours. Residual test substance was determined by HPLC. In the preliminary test at 50 °C and pH 4, 7, and 9, degradations were 0.5 %, 1.3% and 0.1 % after 2.4 hours and 32.6 %, 0.0 %, and 3.6 % after 120 hours, respectively. Hence, the test substance was considered to be hydrolytically stable at pH 7 and 9.


In the main test half lifes were determined at 50, 60 and 70°C at pH 4.


From the main study the following half-lifes were obtained at pH 4; 212.5, 94.5 and 44.8 at 50 °C, 60 °C and 70 °C respectively. From these results, the half-life at 25°C was calculated to be 2000.7 h at pH 4.

Description of key information

Reactive Red 245 is hydrolytically stable at pH 7 and 9.

Key value for chemical safety assessment

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

Additional information

In a GLP-compliant hydrolysis study conducted according to OECD Guideline 111 and EEC Guideline L 251/C.10 (1984), hydrolysis of the test substance was tested at varying temperatures and as a function of pH. A preliminary test was conducted at 50 °C at pH 4, 7 and 9 after 2.4 and 120 h. Residual test substance was determined by HPLC. In the preliminary test at 50 °C and pH 4, 7, and 9, degradations were 0.5 %, 1.3 % and 0.1 % after 2.4 hours and 32.6 %, 0.0 %, and 3.6 % , respectively. Hence, the test substance was considered to be hydrolytically stable at pH 7 and 9. In the main test half lifes were determined at 50, 60 and 70 °C at pH 4. From the main study the following half-lifes were obtained at pH 4; 212.5, 94.5 and 44.8 at 50 °C, 60 °and 7 0°, respectively. From these results, the half-life at 25 °C was calculated to be 2000.7 h at pH 4.