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Diss Factsheets

Environmental fate & pathways

Hydrolysis

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Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
24/06/1999 - 29/06/1999
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study was performed under GLP according to the Guideline
Cross-referenceopen allclose all
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Report date:
1999

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
Principles of method if other than guideline:
Not relevant
GLP compliance:
yes (incl. QA statement)
Remarks:
Statement of compliance

Test material

Constituent 1
Chemical structure
Reference substance name:
(±)-dihydro-3-hydroxy-4,4-dimethylfuran-2(3H)-one
EC Number:
201-210-7
EC Name:
(±)-dihydro-3-hydroxy-4,4-dimethylfuran-2(3H)-one
Cas Number:
79-50-5
Molecular formula:
C6H10O3
IUPAC Name:
(±)-dihydro-3-hydroxy-4,4-dimethylfuran-2(3H)-one
Details on test material:
- Name of test material (as cited in study report): DL-Lactone
- Physical state: white cristalline mass
- Stability under test conditions: stable
- Storage condition of test material: at room temperature in the dark
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not relevant
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
To prepare DL-LACTONE stock solutions, scrapings of the white crystalline mass were
accurately weighed into suitable volumetric flasks and thereafter dissolved in Milli-Q water. In
order to dissolve the test substance completely, the solutions were sonicated for 5 minutes
On each day of analysis, two calibration solutions in mobile phase were made up from two stock
solutions (0.72 g/l and 1.3 g/l). As internal standard, 4-hydroxy-6-methyl-2-pyrone was added to
a final concentration of 2.04 mg/l. 2 ml samples were taken and cooled to room temperature.
Buffers:
A sterile 0.05 M acetate buffer pH 4: sodium acetatelacetic acid/Milli-Q water.
A sterile 0.05 M phosphate buffer pH 7: potassium dihydrogen phosphate/ sodium hydroxide1Milli-Q water.
A sterile 0.05 M borate buffer pH 9: boric acid/potassium chloride/sodium hydroxidelMilli-Q water.
A sterile 0.5 M borate buffer pH 9: boric acid/potassium chloride/sodium hydroxide1Milli-Q water.
Estimation method (if used):
Not used.
Details on test conditions:
Preparation of the test solutions:
Scrapings of the white crystalline test substance mass were used to prepare DL-LACTONE
solutions. An accurately weighed amount between 63 and 66 mg test substance was added to 50.0 ml
buffer solution pH 4, pH 7 and pH 9 (0.05 M and 0.5 M). After sonication for 5 minutes, the
resultant solutions were filter-sterilized through a 0.2 pm membrane filter and transferred into sterile glass vessels.
To exclude oxygen, nitrogen gas was bubbled through each solution for 5 minutes. Thereafter, each vessel was
tightly sealed with a septum-crimpcap.

Test procedure (preliminary test according to EEC Guideline C.7.):
After preparation, the test solutions at pH 4, pH 7 and pH 9 (0.05 M and 0.5 M) were placed in a
thermostatically controlled waterbath at 50.0 2 0.5"C in the dark. The concentration of the test
substance was determined immediately after preparation (t=O), after 2.4 hours and after 5 days.
pH measurements:
For each test solution, the pH value at room temperature was determined for each sample taken.
Duration of testopen allclose all
Duration:
5 d
pH:
4
Temp.:
50
Initial conc. measured:
1 361 mg/L
Duration:
5 d
pH:
7
Temp.:
50
Initial conc. measured:
1 202 mg/L
Duration:
5 d
pH:
9
Temp.:
50
Initial conc. measured:
81.4 mg/L
Number of replicates:
One incubation per pH point.
Concentration measurements: duplicate analysis
Positive controls:
no
Negative controls:
yes
Remarks:
blank buffers
Statistical methods:
Mean values of duplicate analysis.

Results and discussion

Preliminary study:
Only preliminary study was performed
Test performance:
Not relevant
Transformation products:
not measured
Details on hydrolysis and appearance of transformation product(s):
Not relevant
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
50 °C
DT50:
> 1 yr
Type:
not specified
pH:
7
Temp.:
50 °C
DT50:
> 1 d
Type:
not specified
pH:
9
Temp.:
50 °C
DT50:
> 1 d
Type:
not specified
Other kinetic parameters:
Not relevant
Details on results:
The nominal concentration was 1300 mg/l and 1306 mg/l for the pH 9 (0.05 M) solution and the
pH 9 (0.5 M) solution, respectively. Relative to nominal concentrations of 26% and 6% were
analyzed at t=O for these solutions. Possibly D,L-LACTONE transforms at pH > 8 or the
solubility of D,L-LACTONE is significantly lower at pH >8.
At pH 4, a decrease in concentration <10% was observed after 5 days. Hence it was concluded
that D,L-LACTONE is hydrolytically stable at pH 4 (half-life time at 25°C > 1 year), under the
conditions of the test.
At pH 7 and pH 9, a decrease in concentration < 50% after 2.4 hours but > 10% after 5 days
was observed. Hence it was concluded that at both pH 7 and pH 9, the half-life time at 25°C is
between 1 day and 1 year, under the conditions of the test.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
For pH 4, the half-life at 25°C of DL-Lactone is > 1 year; for pH 7, and 9 between 1 day and 1 year.
Executive summary:

The determination of the hydrolysis as a function of pH was based on the EEC-Directive 92/69

EEC, Part C, Methods for the determination of Ecotoxicity, C.7: "Abiotic degradation: Hydrolysis

as a function of pH".

DL-LACTONE was determined to be hydrolytically stable at pH 4 (half-life time at 25°C > 1

year), under the conditions of the test.

At both pH 7 and pH 9, the half-life time at 25°C was determined to be between 1 day and

1 year.