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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:
26 Sep - 12 Nov 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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
GLP compliance:
yes (incl. certificate)
Remarks:
Staatliche Gewerbeaufsicht Hildesheim, Germany
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products: at test start (0 h) and test end (127 h)
- Sample storage conditions before analysis: Samples were analysed immediately (if possible, less than 30 min until start of analyses, but at least not more than 2.5% of the total study time).
Buffers:
- pH: 4, 7, 9
- Composition of buffer: pH 4 (0.18 g (nominal) of NaOH and 5.7555 g (nominal) of mono potassium citrate were dissolved in 500 mL double distilled water), pH 7 (0.7358 g (nominal) of NaOH and 4.3012 g (nominal) of KH2PO4 were dissolved in 500 mL double distilled water), pH 9 (0.426 g (nominal) NaOH, 1.8638 g (nominal) KCl and 1.5458 g (nominal) H3BO3 were dissolved in 500 mL double distilled water)
- Preparation of buffer solutions: Buffer solutions were prepared by direct weighing of the buffer components. Buffers were purged with nitrogen for 5 min and then the pH was checked to a precision of at least 0.1 at the test temperature. Buffers were sterilized by filtration through 0.2 µm. Analytical grade chemicals were used.
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: HPLC vials, 4 mL volume
- Sterilisation method: Filtration through 0.2 µm
- Lighting: opaque water baths to avoid photolytic effects
- Is there any indication of the test material adsorbing to the walls of the test apparatus? no

TEST MEDIUM
- Volume used/treatment: 4 mL
- Kind and purity of water: double distilled water
- Preparation of test medium: The test solution was prepared at test start via test item stock solution in acetonitrile (25 g/L). Sterile buffer solutions were spiked with the stock solution and filled into the test containers
- Identity and concentration of co-solvent: acetonitrile, ≤ 1% (v/v)

OTHER TEST CONDITIONS
- Adjustment of pH: no
Duration:
127 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
48 mg/L
Duration:
127 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
49.4 mg/L
Duration:
127 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
48.4 mg/L
Number of replicates:
Duplicate samples
Positive controls:
no
Negative controls:
no
Preliminary study:
The preliminary study indicated that the substance is not subject to hydrolysis. No further testing was deemed necessary as less than 10% of the applied test item was transformed after 127 h (5 d) at a temperature of 50 °C and each of the three pH values.
Transformation products:
not measured
% Recovery:
99.58
pH:
4
Temp.:
50 °C
Duration:
127 h
% Recovery:
99.8
pH:
7
Temp.:
50 °C
Duration:
127 h
% Recovery:
99.59
pH:
9
Temp.:
50 °C
Duration:
127 h
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: extrapolation from 50 °C to 25 °C according to OECD 111
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: extrapolation from 50 °C to 25 °C according to OECD 111
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: extrapolation from 50 °C to 25 °C according to OECD 111
Details on results:
TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes
Validity criteria fulfilled:
yes
Conclusions:
The hydrolysis test resulted in hydrolysis < 10% after 5 d at pH 4, 7 and 9 and 50 °C. Thus, a DT50 > 1 yr at pH 4, 7 and 9 and 25 °C was extrapolated in accordance with the guideline (OECD 111, GLP). Thus, the substance is hydrolytically stable.
Executive summary:

One experimental study is available investigating the hydrolytic properties of the test substance (2015). The study was performed according to OECD 111 (GLP). A preliminary test with a concentration of approx. 48 mg/L was performed at 3 different pH values and 50 °C. The result from HPLC-DAD analysis indicated that the test substance is hydrolytically stable. After 5 d, < 10% hydrolysis was observed at pH 4, 7 and 9 and 50 °C. Thus, in accordance with the guideline no main test was considered necessary and the results from the preliminary test were extrapolated to 25 °C. At 25 °C the DT50 of the test substance was estimated to be > 1 yr at pH 4, 7 and 9.

Description of key information

The hydrolysis test resulted in hydrolysis < 10% after 5 d at pH 4, 7 and 9 and 50 °C. Thus, a DT50 > 1 yr at pH 4, 7 and 9 and 25 °C was extrapolated in accordance with the guideline (OECD 111, GLP). Thus, the substance is hydrolytically stable.

Key value for chemical safety assessment

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

Additional information

One experimental study is available investigating the hydrolytic properties of the test substance (2015). The study was performed according to OECD 111 (GLP). A preliminary test with a concentration of approx. 48 mg/L was performed at 3 different pH values and 50 °C. The result from HPLC-DAD analysis indicated that the test substance is hydrolytically stable. After 5 d, < 10% hydrolysis was observed at pH 4, 7 and 9 and 50 °C. Thus, in accordance with the guideline no main test was considered necessary and the results from the preliminary test were extrapolated to 25 °C. At 25 °C the DT50 of the test substance was estimated to be > 1 yr at pH 4, 7 and 9.