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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:
1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
GLP compliance:
yes
Radiolabelling:
yes
Remarks:
with 14C
Analytical monitoring:
yes
Buffers:
- pH 5: The 0.01M soldium acetate (NaOAc) buffer was prepared by combining 35.2 mL of 0.2M NaOAc and 14.8 mL of 0.2M acetic acid (HOAc) and diluting the mixture to a total volume of 1000mL with NANOPure water. The pH measured 5.00.
- pH 7: 25mL of 0.2M tris (hydoxymethyl) aminomethane in water was combined with 22.1mL of 0.2M hydrochloric acid (HCl). THe total volume was adjusted to 1000mL with NANOPure water, which procided a 0.01M solution. The pH was adjusted to a final pH of 7.00 using 0.2 M HCl.
- pH9: The 0.01M boric acid (H3BO3) buffer was made by dissolving 0.3g of boric acid in 500mL of 0.01M potassium chloride (KCl). The solution was transferred to a 1000mL volumetric flask, and approximately 170mL of 0.01M sodium hydroxide (NaOH) was added. The mixture was diultet with NANOPure water. The pH measured 8.98.
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used:
- Sterilisation method:
- Lighting:
- Measures taken to avoid photolytic effects:
- Measures to exclude oxygen:
- Details on test procedure for unstable compounds:
- Details of traps for volatile, if any
- If no traps were used, is the test system closed/open
- Is there any indication of the test material adsorbing to the walls of the test apparatus?
TEST MEDIUM
- Volume used/treatment
- Kind and purity of water:
- Preparation of test medium:
- Renewal of test solution:
- Identity and concentration of co-solvent:
OTHER TEST CONDITIONS
- Adjustment of pH:
- Dissolved oxygen:
Duration:
30 d
pH:
5
Temp.:
25 °C
Duration:
30 d
pH:
7
Temp.:
25 °C
Duration:
30 d
pH:
9
Temp.:
25 °C
Number of replicates:
2
Positive controls:
no
Negative controls:
no
Preliminary study:
Duplicate samples of each pH level were taken at 0, 3 and 7 days post treatment. Duplicate aliquots were taken for LSC, samples were then extracted by solid phase extraction and analyzed by HPLC. Sample recovery after 7 days was around 100%. Half-life was calculated to be between 63 and 188 days.
Transformation products:
no
% Recovery:
102.61
pH:
5
Temp.:
25 °C
Duration:
30 d
% Recovery:
101.56
pH:
7
Temp.:
25 °C
Duration:
30 d
% Recovery:
101.4
pH:
9
Temp.:
25 °C
Duration:
30 d
pH:
5
Temp.:
25 °C
DT50:
4 331 d
Key result
pH:
7
Temp.:
25 °C
DT50:
1 443.75 d
pH:
9
Temp.:
25 °C
DT50:
4 620 d
Details on results:
TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes

INDICATION OF UNSTABLE TRANSFORMATION PRODUCTS: no

The average total 14C-recoveries throughout the incubation period for aqueous solutions buffered at pH 5, 7 and 9 yielded excellent results (101.64%, 101.03% and 101.36%, respectively), indicating no volatile degradates were formed during the hydrolytic process. HPLC analysis of the organic extractable fraction showed no degradation of the test item at all three pH levels. Only one substance (average 0.99 - 1.68%) was observed additional to the test item, which was proved to be not a hydrolytic product but an impurity in the test substance.

Validity criteria fulfilled:
yes
Conclusions:
The half-live of the test item is at least 1444 days.
Executive summary:

Under sterile conditons at 25 °C in the dark, the test item is very stable in buffered aqueous solutions at pH levels of 5, 7 and 9. The observed half-lives of the test item ranged from 1444 to 4620 days. In addition to the parent compound, one other substance was observed during the study. Further investigations using HPLC co-chromatography proved the substance was not a true hydrolytic degradate but an impurity associated with the test chemical. The parent compound was confirmed chromatographically by RP-HPLC and LC/MS.

Description of key information

The half-live of the test item is at least 1444 days.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 444 d
at the temperature of:
25 °C

Additional information

Under sterile conditons at 25 °C in the dark, the test item is very stable in buffered aqueous solutions at pH levels of 5, 7 and 9. The observed half-lives of the test item ranged from 1444 to 4620 days. In addition to the parent compound, one other substance was observed during the study. Further investigations using HPLC co-chromatography proved the substance was not a true hydrolytic degradate but an impurity associated with the test chemical. The parent compound was confirmed chromatographically by RP-HPLC and LC/MS.