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Environmental fate & pathways

Hydrolysis

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Administrative data

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2000
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)
GLP compliance:
yes
Specific details on test material used for the study:
IR5878 (unlabelled substance)
98.72% pure
Batch number 20398/70/A
IR5878 (radiolabelled)
Radiolabelling:
yes
Analytical monitoring:
yes
Details on sampling:
At chosen sampling times each sample was directly analysed by LSC to establish the radioactivity content and by TLC and HPLC to profile the radiolabelled hydrolysis compounds.
Buffers:
pH4: 0.01M acetate
0.1476g of sodium acetate were weighed into 1L flask and disolved with 500mL CO2 free distilled water. The pH was adjusted to 4.0 with 4.69mL of 1.75N acetic acid.

pH7: 0.01M citrate
1.921g of citric acid dissoled with 250mL of CO2 free distilled water. PH was adjusted to 7 with 285mL of 0.1N sodium hydroxide.

pH9:0.01M borate
0.620g boric acid and 0.746g of potassium chloride dissolved with 500mL CO2 free distilled water. pH was adjusted to 9.0 with 43mL of 0.1N sodium hydroxide.
Details on test conditions:
Sterile conditions
50C
In darkness
Transformation products:
yes
No.:
#1
No.:
#2
No.:
#3
No.:
#4
Details on hydrolysis and appearance of transformation product(s):
The profile of hydrolysis samples at each pH value showed the presence of four compounds name H1, H2, H3 and H4. Compound H3 was unchanged IR5878.
% Recovery:
ca. 0
pH:
4
Temp.:
50 °C
Duration:
ca. 1 d
% Recovery:
ca. 32.91
pH:
7
Temp.:
25 °C
Duration:
ca. 37 d
% Recovery:
ca. 3.12
pH:
7
Temp.:
50 °C
Duration:
ca. 166 h
% Recovery:
ca. 56.19
pH:
9
Temp.:
50 °C
Duration:
ca. 176 d
% Recovery:
ca. 6.85
pH:
9
Temp.:
50 °C
Duration:
ca. 29 d
Key result
pH:
4
Temp.:
50 °C
Hydrolysis rate constant:
ca. 1.602 h-1
DT50:
ca. 0.43 h
Key result
pH:
7
Temp.:
50 °C
Hydrolysis rate constant:
ca. 0.02 h-1
DT50:
ca. 35.36 h
Key result
pH:
9
Temp.:
50 °C
Hydrolysis rate constant:
ca. 0.087 h-1
DT50:
ca. 7.96 d
Key result
pH:
7
Temp.:
25
Hydrolysis rate constant:
ca. 0.028 h-1
DT50:
ca. 24.4 d
Key result
pH:
9
Temp.:
25 °C
Hydrolysis rate constant:
ca. 0.003 h-1
DT50:
ca. 227.96 d

Hydrolysis rate of purified active substance at pH values 4, 7 and 9 under sterile conditions in the absence of light was investigated according to EEC method C7. Rate of hydrolysis and half life were found to be as summarised in the table below:

pH

kobs

DT50

4 at 50C

1.602 h-1

0.43h

7 at 50C

0.0196 h-1

35.36 h

9 at 50C

0.0871 d-1

7.96 d

7 at 25C

0.0284 d-1

24.40 d

9 at 25C

0.00304 d-1

227.96 d

h = hours; d = days

Validity criteria fulfilled:
yes
Conclusions:
Degradation of IR5878 was observed at each pH value. Degradation was faster at pH4 but was also significant at pH 7 and pH9. A pseudo first order kinetic hydrolysis reaction was always defined.

The profile of hydrolysis samples at each pH value showed the presence of four compounds named H1, H2, H3, H4. Compound H3 was idenitified as unchanged IR5878, H1 was DBS acid, H2 was DBS amide and H4 was DB amine.

pH kobs DT50
4 at 50°C 1.602 h-1 0.43 h
7 at 50°C 0.0196 h-1 35.36 h
9 at 50°C 0.0871 d-1 7.96 d
7 at 25°C 0.0284 d-1 24.40 d
9 at 25°C 0.00304 d-1 227.96 d
h = hours; d = days
Executive summary:

Hydrolysis rate of purified active substance at pH values 4, 7 and 9 under sterile conditions in the absence of light was investigated according to EEC method C7. Rate of hydrolysis and half life were found to be as summarised in the table below:

pH

kobs

DT50

4 at 50C

1.602 h-1

0.43h

7 at 50C

0.0196 h-1

35.36 h

9 at 50C

0.0871 d-1

7.96 d

7 at 25C

0.0284 d-1

24.40 d

9 at 25C

0.00304 d-1

227.96 d

h = hours; d = days

Description of key information

Hydrolysis rate of purified active substance at pH values 4, 7 and 9 under sterile conditions in the absence of light was investigated according to EEC method C7. Rate of hydrolysis and half life were found to be as summarised in the table below:

pH

kobs

DT50

4 at 50C

1.602 h-1

0.43h

7 at 50C

0.0196 h-1

35.36 h

9 at 50C

0.0871 d-1

7.96 d

7 at 25C

0.0284 d-1

24.40 d

9 at 25C

0.00304 d-1

227.96 d

h = hours; d = days

Key value for chemical safety assessment

Half-life for hydrolysis:
24.4 d
at the temperature of:
25 °C

Additional information