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Diss Factsheets

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 2002-08-16 to 2002-12-02
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report date:
2003

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
yes
Remarks:
No identification of degradation products
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
2-ethylhexyl mercaptoacetate
EC Number:
231-626-4
EC Name:
2-ethylhexyl mercaptoacetate
Cas Number:
7659-86-1
Molecular formula:
C10H20O2S
IUPAC Name:
2-ethylhexyl 2-sulfanylacetate
Details on test material:
- Physical state: colorless liquid
- Storage condition of test material: at room temperature and protected from light
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent product:
Preliminary test
pH 4.0, 7.0 and 9.0
0 hour, 2.4 hours and 72 hours at 50°C.

Main test
First temperature (50°C)
pH 4.0, 7.0 and 9.0
· 0, 1.17, 1.50, 1.83, 2.17, 2.50 and 2.83 hours (pH 4.0),
· 0, 0.50, 0.83, 1.50, 1.83, 2.17, 2.50 and 2.83 hours (pH 7.0),
· 0, 1.17, 1.50, 1.83, 2.17, 2.50 and 2.83 hours (pH 9.0).

Second temperature (66°C)
pH 4.0 and 7.0
· 0, 0.50, 0.83, 1.17, 1.50, 1.83 and 2.17 hours (pH 4.0),
· 0, 0.50, 0.83, 1.17, 1.50, 1.83 and 2.17 hours (pH 7.0).
pH 9.0
· 0, 0.50, 0.83, 1.17, 1.50, 1.75 and 2.00 hours (pH 9.0).

Third temperature (80°C)
pH 4.0, 7.0 and 9.0
· 0, 0.50, 0.67, 0.83, 1.00, 1.17 and 1.33 hours (pH 4.0),
· 0, 0.33, 0.50, 0.67, 0.83, 1.00, 1.17, 1.33 and 1.50 hours (pH 7.0),
· 0, 0.33, 0.50, 0.67, 0.83, 1.00 and 1.17 hours (pH 9.0).

Repeated temperature (66°C)
pH 4.0, 7.0 and 9.0
· 0, 0.83, 1.17, 1.50, 1.83, 2.17 and 2.50 hours (pH 4.0),
· 0, 0.50, 0.83, 1.17, 1.50, 1.83 and 2.17 hours (pH 7.0),
· 0, 0.50, 0.83, 1.17, 1.50, 1.83 and 2.17 hours (pH 9.0).

Temperature for pH 1.2 (37°C)
pH 4.0, 7.0 and 9.0
· 0, 2.50, 3.00, 3.50, 4.50, 5.50, 6.50 and 7,5 hours.

- Sampling method:
An aliquot of each sample was extracted and analyzed by Gas Liquid Chromatography with Flame Ionization Detection (FID).

- Sampling intervals/times for pH measurements:
Same as "Sampling intervals for the parent product"

- Other observation, if any (e.g.: precipitation, color change etc.):
Colors of the resulting solutions were observed at the end of tests.
Buffers:
An aliquot (mg) of test system was dissolved in a 100-mL volumetric flask. The flask was made to volume with ethylic alcohol (stock solution).
An aliquot of stock solution was introduced in a volumetric flask and each flask was made to volume with respectively buffer
pH 4.0, 7.0 and 9.0. These obtained solutions were transferred in test bottles protected from light.

Preliminary test
pH 4.0, 7.0 and 9.0 at 50°C
Amount of the test item used for preparation of stock solution: 103.1 mg.
Volume of stock solution used for preparation of buffer solution: 0.2 mL.
Volume of volumetric flask used for buffer solution: 100 mL.

Main test
First temperature (50°C)
pH 4.0, 7.0 and 9.0
Amount of the test item used for preparation of stock solution: 51.4 mg.
Volume of stock solution used for preparation of buffer solution: 0.9 mL.
Volume of volumetric flask used for buffer solution: 200 mL.

Second temperature (66°C)
pH 4.0 and 7.0
Amount of the test item used for preparation of stock solution: 50.0 mg.
Volume of mother solution used for preparation of buffer solution: 0.45 mL.
Volume of volumetric flask used for buffer solution: 100 mL.
pH 9.0
Amount of the test item used for preparation of stock solution: 50.6 mg.
Volume of stock solution used for preparation of buffer solution: 0.47 mL.
Volume of volumetric flask used for buffer solution: 100 mL.

Third temperature (80°C)
pH 4.0, 7.0 and 9.0
Amount of the test item used for preparation of stock solution: 53.5 mg.
Volume of stock solution used for preparation of buffer solution: 0.9 mL.
Volume of volumetric flask used for buffer solution: 200 mL.

Repeated temperature (66°C)
pH 4.0, 7.0 and 9.0
Amount of the test item used for preparation of stock solution: 43.8 mg.
Volume of stock solution used for preparation of buffer solution: 0.9 mL.
Volume of volumetric flask used for buffer solution: 100 mL.

Temperature for pH 1.2 (37°C)
pH 4.0, 7.0 and 9.0
Amount of the test item used for preparation of stock solution: 99.4 mg.
Volume of stock solution used for preparation of buffer solution: 0.6 mL
Volume of volumetric flask used for buffer solution: 250 mL
Duration of testopen allclose all
Duration:
2.83 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
1.93 mg/L
Duration:
2.83 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
2 mg/L
Duration:
2.83 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
2.02 mg/L
Duration:
2.17 h
pH:
4
Temp.:
66 °C
Initial conc. measured:
1.78 mg/L
Duration:
2.17 h
pH:
7
Temp.:
66 °C
Initial conc. measured:
1.8 mg/L
Duration:
2 h
pH:
9
Temp.:
66 °C
Initial conc. measured:
2.03 mg/L
Duration:
1.33 h
pH:
4
Temp.:
80 °C
Initial conc. measured:
1.77 mg/L
Duration:
1.5 h
pH:
7
Temp.:
80 °C
Initial conc. measured:
1.7 mg/L
Duration:
1.17 h
pH:
9
Temp.:
80 °C
Initial conc. measured:
1.77 mg/L
Duration:
7.5 h
pH:
1.2
Temp.:
38 °C
Initial conc. measured:
1.59 mg/L
Number of replicates:
2 replicates per assay (temperature and pH) were measured.
At 66°C, tests were repeated. Therefore, at 66°C and all tested pH, 4 replicates were measured.
Positive controls:
no
Negative controls:
no
Statistical methods:
The concentrations of 2-EHTG were determined from a calibration curve obtained by linear regression analysis of respective ratio test item peak area/Internal Standard peak area versus concentration of standard solutions ranging from 0.5 to 50 mg/L.

Results and discussion

Preliminary study:
During the preliminary test, the degradation of 2-EHTG, at each pH value, indicated an hydrolysis lower than 50% after 2.4 hours and higher than 10% after 3 days. 2-EHTG was considered as hydrolytically unstable. The hydrolysis rate was then determined at three different temperatures (50°C, 66°C (twice) and 80°C) for each buffer and one temperature (37°C) for pH = 1.2. The determination was performed to cover approximately 20-70% hydrolysis.
Transformation products:
not measured
Total recovery of test substance (in %)open allclose all
% Recovery:
54
pH:
4
Temp.:
50 °C
Duration:
2.83 h
% Recovery:
51
pH:
7
Temp.:
50 °C
Duration:
2.83 h
% Recovery:
55
pH:
9
Temp.:
50 °C
Duration:
2.83 h
% Recovery:
32
pH:
4
Temp.:
66 °C
Duration:
2.17 h
% Recovery:
31
pH:
7
Temp.:
66 °C
Duration:
2.17 h
% Recovery:
35
pH:
9
Temp.:
66 °C
Duration:
2 h
% Recovery:
35
pH:
4
Temp.:
80 °C
Duration:
1.33 h
% Recovery:
31
pH:
7
Temp.:
80 °C
Duration:
1.5 h
% Recovery:
30
pH:
9
Temp.:
80 °C
Duration:
1.17 h
% Recovery:
45
pH:
1.2
Temp.:
38 °C
Duration:
7.5 h
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
DT50:
ca. 12 h
pH:
7
Temp.:
25 °C
DT50:
ca. 12 h
pH:
9
Temp.:
25 °C
DT50:
ca. 16 h
pH:
1.2
Temp.:
37 °C
DT50:
ca. 6.8 h
Details on results:
The values of the t½ at 25°C for each pH were obtained by extrapolation, as no test was conducted at this temperature.
For total recovery of test substance, mean results for n=2 are reported at all temperatures except at 66°C, where mean results are reported for n = 4.

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
The substance was found to be hydrolytically unstable at 25°C, with estimated half-lives ranging from 12 to 16 hours at pH from 4 to 9, respectively.
Executive summary:

The hydrolysis rate was determined according to the test OECD Guideline 111. The substance was found to be hydrolytically unstable at 25°C, with estimated half-lives ranging from 12 to 16 hours at pH from 4 to 9, respectively. Half-life was 6.8 at 37°C and pH 1.2.

Advanced tests results were the following:

Kobs = 0.0580 h-1 and t½ = 12 h at 25°C for pH 4.0 (estimation),

Kobs = 0.0594 h-1 and t½ = 12 h at 25°C for pH 7.0 (estimation),

Kobs = 0.0422 h-1 and t½ = 16 h at 25°C for pH 9.0 (estimation),

Kobs = 0.102 h-1 and t½ = 6.8 h at 37°C for pH 1.2.