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Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report date:
2008

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Remarks:
- The study was conducted according to the test guidelines in effect at the time of study conduct.
Qualifier:
according to guideline
Guideline:
EPA OPPTS 835.2110 (Hydrolysis as a Function of pH)
Deviations:
no
Remarks:
- The study was conducted according to the test guidelines in effect at the time of study conduct.
GLP compliance:
yes

Test material

Constituent 1
Reference substance name:
Reference substance 002
Cas Number:
62037-80-3
Details on test material:
- Purity: 86%

Study design

Analytical monitoring:
yes
Details on sampling:
The hydrolysis potential was evaluated at pH 4 (acetate buffer), 7 (phosephate buffer) and 9 (borate buffer) at 50ºC over a five day period. Samples were collected and analyzed on Days 0 and 5. Autoclaved 8 mL vials were filled in triplicate with the test material. An additional sample was decanted into an autoclaved 20 mL vial for pH measurement after five days incubation at 50ºC. The four secondary vessels were capped, placed into a rack and the rack was placed into a 50 ºC incubator. Day 0 sub-samples from each of the three pH levels were removed from the original preparation volumes and each processed in triplicate and taken for immediate test substance concentration determination to confirm dosing. For each pH level, sub-samples from each to the triplicate incubated samples were processed after incubation for five days at 50 ºC to evaluate the hydrolysis potential of the test substance.

Buffers:
- pH: 4
- Type and final molarity of buffer: Acetate
- Composition of buffer: 4.1015 g of sodium acetate and 16.6910 g of acetic acid in a graduated cylinder with reagent-grade water. The final volume of the solution was adjusted to 1000 mL with reagent grade water. The final pH of the solution was adjusted with an appropriate volume of 0.1M sodium hydroxide solution (4.0016 g NaOH transferred into a 100-mL volumetric flask and brought to final volume with reagent water)
- pH: 7
- Type and final molarity of buffer: Phosphate
- Composition of buffer: Mixed 6.8039 g of potassium dihydrogen phosphate and 1.1871 g of NaOH in a graduated cylinder with reagent-grade water. The final volume of the solution was adjusted to 1000 mL with reagent water.
- pH: 9
- Type and final molarity of buffer: Borate
- Composition of buffer: Mixed 3.7280 g of potassium chloride, 3.0914 g of boric acid and 0.8882 g of NaOH in a volumetric flask with reagent-grade water. The final volume of the solution was adjusted to 1000 mlLwith reagent water.

Each buffer solution was degassed with nitrogen for approximately five minutes to reduce dissolved oxygen concentrations. The pH of each aqueous buffer solution was then measured using a pH meter at room temperature with an accuracy of ±0.01 pH unit. Prior to use, the resulting pH- adjusted aqueous buffer solutions used for testing were vacuum filtered through 0.2 µm filters.
Details on test conditions:
All samples were prepared fortifying 100 mL of the appropriate buffered water with 200 µL of a 5.00 mg/mL stock solution of the test substance in methanol using a positive displacement pipetter. The resultant nominal concentration was 8.60 mg a.s./L in all solutions. The samples were added directly into volumetric flasks containing the appropriate buffered water. After preparation, each aqueous buffer solution was decanted into secondary vessels as follows: autoclaved 8 mL vials were filled in triplicate. An additional sample was decanted into an autoclaved 20 mL vial for pH measurement after five days incubation at 50ºC. The four secondary vessels were capped, placed into a rack and the rack was placed into the 50ºC incubator in darkness. Day 0 sub-samples from each of the three pH levels were removed from the original preparation volumes and each processed in triplicate and taken for the test substance concentration determination to confirm dosing.
Duration of test
Duration:
5 d
Temp.:
50 °C
Initial conc. measured:
8.6 other: mg a.s/L
Number of replicates:
3
Statistical methods:
Reported values were calculated using Analyst®1.4.2.

Results and discussion

Preliminary study:
The hydrolytic stability of the test substance was evaluated at pH 4, 7, and 9, at 50ºC over a five day period. No degradation was evident in triplicate samples prepared in pH 4, 7, and 9 buffer solutions after a five day incubation period at the elevated temperature. Therefore, no further work was done.
Transformation products:
no
Total recovery of test substance (in %)open allclose all
% Recovery:
105
pH:
4
Temp.:
50 °C
Duration:
0 d
% Recovery:
95.5
pH:
4
Temp.:
50 °C
Duration:
5 d
% Recovery:
105
pH:
7
Temp.:
50 °C
Duration:
0 d
% Recovery:
94.5
pH:
7
Temp.:
50 °C
Duration:
5 d
% Recovery:
102
pH:
9
Temp.:
50 °C
Duration:
0 d
% Recovery:
93.5
pH:
9
Temp.:
50 °C
Duration:
5 d
Dissipation DT50 of parent compound
Key result
Remarks on result:
hydrolytically stable based on preliminary test

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
This study and the conclusions which are drawn from it fulfill the quality criteria (validity, reliability, repeatability).
Conclusions:
No degradation was evident in triplicate samples prepared in pH 4, 7, and 9 buffer solutions after a 5-day incubation period at the elevated temperature. The test substance was considered hydrolytically stable over the environmentally relevant pH range with a half-life (t½) greater than 1 year.
Executive summary:

The hydrolysis potential of the test substance was evaluated at pH 4 (acetate buffer), 7 (phosphate buffer) and 9 (borate buffer) at 50ºC over a five-day period. Samples were collected and analyzed on Days 0 and 5. Representative chromatograms of the Day 5 pH 4, 7, and 9 samples were saved. Day 0 samples prepared in pH 4, 7, and 9 aqueous buffer solutions yielded mean measured values of 9.02± 0.262 mg a.s./L, 9.02± 0.215 mg a.s./L, and 8.77± 0.225 mg a.s./L, respectively. The values corresponded to mean percent recoveries of 105%, 105%, and 102% of the nominal concentration. Day 5 samples prepared in pH 4, 7, and 9 aqueous buffer solutions yielded mean measured values of 8.21± 0.167 mg a.s./L, 8.13± 0.165mg a.s./L, and 8.04± 0.164 mg a.s./L, respectively. The values corresponded to mean percent recoveries of 95.5%, 94.5%, and 93.5% of the nominal concentration. The Day 5 mean percent recoveries for the pH 4, 7, and 9 aqueous buffer solutions were 91.0%, 90.0% and 91.7%, respectively, of those obtained on Day 0. On the basis of these findings, the experiment was terminated at the conclusion of the preliminary trial.

No degradation was evident in triplicate samples prepared in pH 4, 7, and 9 buffer solutions after a 5-day incubation period at the elevated temperature. The test substance was considered hydrolytically stable over the environmentally relevant pH range with a half-life (t½) greater than 1 year.