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Environmental fate & pathways

Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From September 6 to 12, 2005
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
This study was performed according to OECD Guideline 111 and EU Method C.7 with GLP statement. All validity criteria were fulfilled.
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
UK GLP Compliance Programme (inspected on April 12, 2005 / signed on June 1, 2005)
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sampling method: At each sampling time, an aliquot (1 mL) was diluted to volume (10 mL) with mobile phase for analysis by high performance liquid chromatography (HPLC).
- Sampling time: 5 mins, 2.4 hours and 120 hours
- Sample pH and incubation temperature were monitored over the period of the test.
Buffers:
- pH: 4.0
- Composition of buffer: Potassium dihydrogen orthophosphate, disodium hydrogen orthophosphate dodecahydrate, water. pH adjusted with orthophosphoric acid.

- pH: 7.0
- Composition of buffer: Potassium dihydrogen orthophosphate, water, 1M sodium hydroxide. pH adjusted with1M hydrochloric acid

- pH: 9.0
- Composition of buffer: Disodium tetraborate decahydrate, potassium dihydrogen orthophosphate, water. pH adjusted with 1M hydrochloric acid
Estimation method (if used):
Not applicable
Details on test conditions:
Duplicate aliquots (1 ml) of a stock solution of the tested substance in methanol (20 g/L) were measured into separate 100 mL Wheaton vials containing buffer solution (100 mL), which had been purged with nitrogen and pre-equilibrated at test temperature (50 °C). The samples, of nominal concentration 200 mg/L, were placed in a 50 °C water bath in the dark until sampling.
Duration:
5 d
pH:
4
Temp.:
50 °C
Initial conc. measured:
200 mg/L
Duration:
5 d
pH:
7
Temp.:
50 °C
Initial conc. measured:
200 mg/L
Duration:
5 d
pH:
9
Temp.:
50 °C
Initial conc. measured:
200 mg/L
Number of replicates:
Duplicate
Positive controls:
no
Negative controls:
no
Statistical methods:
No data available
Preliminary study:
See below
Test performance:
No data
Transformation products:
not measured
Details on hydrolysis and appearance of transformation product(s):
No data
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
Other kinetic parameters:
No data
Details on results:
There was no significant change in the concentration of tested substance when incubated in pH 4, 7 and 9 buffer solutions at 50 ± 0.5 °C. Less than 10% hydrolysis had occurred after 120 hours (5 days) under these conditions, equivalent to a half-life of greater than 1 year under environmental conditions (25 °C).
There were no significant changes in pH with time.

Table 5.1.2/1: Preliminary investigation results for hydrolysis of test item

pH

Ct (mg/L)

t0h

t2.4h

t120h

Measured

Mean

Measured

Mean

Measured

Mean

4

207, 206

207

205, 204

205

205, 207

206

7

210, 198

204

205, 205

205

209, 206

207

9

204, 205

205

205, 206

206

207, 209

208

 

where Ct is the concentration of test item in solution at time th (in hours)

Validity criteria fulfilled:
yes
Conclusions:
Test item was determined to be hydrolytically stable under acidic, neutral and basic conditions.
Executive summary:

A study was performed according to OECD 111/ EU Method C.7 with GLP compliance to determine the rate of hydrolysis of test item as a function of pH.

The preliminary study showed that at pH 4, 7 and 9 and 50 ± 0.5 °C, less than 10% hydrolysis had occurred after 120 hours (5 days), equivalent to a half-life of greater than 1 year under environmental conditions (25 °C). There were no significant changes in pH with time.

Test item was determined to be hydrolytically stable under acidic, neutral and basic conditions.

Description of key information

OECD Guideline 111, GLP, key study, validity 1:

Half-life for hydrolysis (25°C) >1 year

Key value for chemical safety assessment

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

Additional information

A study was performed according to OECD 111/ EU Method C.7 with GLP compliance to determine the rate of hydrolysis of test item as a function of pH.

The preliminary study showed that at pH 4, 7 and 9 and 50 ± 0.5 °C, less than 10% hydrolysis had occurred after 120 hours (5 days), equivalent to a half-life of greater than 1 year under environmental conditions (25 °C). There were no significant changes in pH with time.

Test item was determined to be hydrolytically stable under acidic, neutral and basic conditions.