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Environmental fate & pathways

Hydrolysis

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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:
other: GLP study report available

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guidelineopen allclose all
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)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
The following procedure was carried out at each of pH 4, 7 and 9:
Duplicate aliquots (10 ml) of a stock solution of substance in purified water (1 g/l)
were added to separate 100 ml Wheaton vials containing buffer solution (90 ml), which had
been purged with nitrogen and pre-equilibrated at test temperature (50°C). The samples, of
nominal concentration 100 mg/l, were placed in a 50°C waterbath in the dark until sampling
was required (after a short incubation period of approximately 5 minutes, and then after
2.4 and 120 hours). 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).
Sample pH and incubation temperature were monitored over the period of the test.
Buffers:
Preparation of buffer solutions
pH 4.0 : Potassium dihydrogen orthophosphate (6.0 g) and disodium hydrogen orthophosphate dodecahydrate (12.8 g) were dissolved in purified
water (1900 ml), and the pH was adjusted to 4.0 ± 0.05 with orthophosphoric acid. The volume was then adjusted to 2000 ml with purified water.

pH 7.0 : Potassium dihydrogen orthophosphate (27.2 g) was dissolved in purified water (3800 ml), 1M sodium hydroxide (120 ml) was added and the pH was adjusted to 7.0 ± 0.05 with 1M hydrochloric acid. The volume was then adjusted to 4000 ml with purified water.

pH 9.0 : Disodium tetraborate decahydrate (66.4 g) and potassium dihydrogen orthophosphate (7.2 g) were dissolved in purified water (3800 ml), andthe pH was adjusted to 9.0 ± 0.05 with 1M hydrochloric acid. The volume was then adjusted to 4000 ml with purified water.
Details on test conditions:
The following procedure was carried out at each of pH 4, 7 and 9:
Duplicate aliquots (10 ml) of a stock solution of VRT-126017 dcha in purified water (1 g/l)
were added to separate 100 ml Wheaton vials containing buffer solution (90 ml), which had
been purged with nitrogen and pre-equilibrated at test temperature (50°C). The samples, of
nominal concentration 100 mg/l, were placed in a 50°C waterbath in the dark until sampling
was required (after a short incubation period of approximately 5 minutes, and then after
2.4 and 120 hours). 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).
Sample pH and incubation temperature were monitored over the period of the test.
Duration of testopen allclose all
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
100 mg/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
100 mg/L
Duration:
120 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
100 mg/L
Number of replicates:
no replicates necessary. Substance is stable under test conditions.
Positive controls:
no
Negative controls:
no
Statistical methods:
Linear regression: y = 48.25x + 3.403
(including x = 0, y = 0), r = 1.0000

Results and discussion

Preliminary study:
Results from the preliminary investigation showed that there was no significant change in the concentration of dcha when incubated
in pH 4, 7 and 9 buffer solutions at 50 ± 0.5 ºC. Less than 10 % hydrolysis had occurred after 120 hours (5 days) under these conditions, equivalent toa half-life of greater than 1 year under environmental conditions (25 °C).
Transformation products:
no
Details on hydrolysis and appearance of transformation product(s):
no transformation produducts observed. Substance is stable under test conditions.
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
DT50:
>= 8 760 h
pH:
7
Temp.:
25 °C
DT50:
>= 8 760 h
pH:
9
Temp.:
25 °C
DT50:
>= 8 760 h

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The test substance was determined to be hydrolytically stable under acidic, neutral and basic conditions.
The half-life time t1/2 for the hydrolytical degradation was detected > 8760 h (pH 7; 25 °C).