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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02 March 2017 - 28 May 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Version / remarks:
13. April 2004
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Version / remarks:
No 440/2008 of 30 May 2008
Deviations:
no
Principles of method if other than guideline:
NA
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Identification: Ethoxy ethoxy ethyl acrylate CAS No. 7328-17-8
Appearance/Physical state: Clear colorless liquid
Lot: 151210177
Purity: 95.49%
Expiry date: 30 June 2017
Storage conditions: Room temperature, in the dark
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
Analysis of the Sample Solutions
The sample solutions were taken from the water bath at various times and the pH of each solution recorded. The concentration of the sample solutions was determined by gas chromatography (GC).

Samples:
For the initial time point, duplicate aliquots of each test solution were diluted by a factor of 4 using acetonitrile.
For the incubated samples, an aliquot of each sample solution (duplicate vessels A and B being removed at each time point) was diluted by a factor of 4 using acetonitrile.

Standards:
Duplicate standard solutions of test item were prepared in 75:25 v/v acetonitrile:relevant buffer solution at a nominal concentration of 250 mg/L.

Matrix blanks:
75:25 v/v acetonitrile:relevant buffer solution.
Buffers:
Specification of the Buffer Solutions

pH=4
Potassium hydrogen phthalate 0.05 mol/dm3
Citric acid; 0.06 mol/dm3
Sodium chloride; 0.04 mol/dm3
Sodium hydroxide; 0.07 mol/dm3

pH=7
Disodium hydrogen orthophosphate (anhydrous); 0.03 mol/dm3
Potassium dihydrogen orthophosphate; 0.02 mol/dm3
Sodium chloride; 0.02 mol/dm3

pH=9
Disodium tetraborate; 0.01 mol/dm3
Sodium chloride; 0.02 mol/dm3

The buffer solutions were subjected to filtration through 0.2 μm filters, ultrasonication and degassing with nitrogen to minimize dissolved oxygen content.
Details on test conditions:
Preliminary Test (Tier 1):
Sample solutions at pH 4, pH 7 and pH 9 were maintained at 50.0 ± 0.5 °C for the following periods of time: 120 h for the pH 4 samples, 672 h for the pH 7 samples and 22 h for the pH 9 samples.

Duplicate, independently incubated samples were removed for analysis at each time point, for each pH value.

Tier 2:
Results from the Preliminary Test/Tier 1 showed it was necessary to undertake further testing at pH 7 and pH 9. Sample solutions were maintained at 60.0 ± 0.5 °C for the following periods of time: 262 h for the pH 7 samples and 7 h for the pH 9 samples. Sample solutions were also maintained 96.5 h at 70.0 ± 0.5 °C for the pH 7 samples and 46.6 h at 40.0 ± 0.5 °C for the pH 9 samples.

Duplicate, independently incubated samples were removed for analysis at each time point, for both pH values


Test item (0.1007 g) was diluted to 100 mL with methanol. The solution was then diluted by a factor of 2 with methanol to give a concentration of 504 mg/L.
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
1 g/L
Remarks:
tier 1
Duration:
672 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
1 g/L
Remarks:
tier 1
Duration:
22 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
1 g/L
Remarks:
tier 1
Duration:
262 h
pH:
7
Temp.:
60 °C
Initial conc. measured:
1 g/L
Remarks:
tier 2
Duration:
7 h
pH:
9
Temp.:
60 °C
Initial conc. measured:
1 g/L
Remarks:
tier 2
Duration:
96.5 h
pH:
7
Temp.:
70 °C
Initial conc. measured:
1 g/L
Remarks:
tier 2
Duration:
46.6 h
pH:
9
Temp.:
40 °C
Initial conc. measured:
1 g/L
Remarks:
tier 2
Number of replicates:
2
Positive controls:
not specified
Negative controls:
not specified
Statistical methods:
NA
Transformation products:
not measured
Key result
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
7
Temp.:
25 °C
Hydrolysis rate constant:
0 h-1
DT50:
313 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
9
Temp.:
25 °C
Hydrolysis rate constant:
0.006 h-1
DT50:
4.65 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
hydrolytically stable based on preliminary test

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 10 to 300 mg/L in 75:25 v/v acetonitrile:relevant buffer solution. This was satisfactory with a goodness of fit coefficient (r2) of 1.000 being obtained for all three matrices.

In most sequences, the analysis of the matrix blank solutions showed a small peak at the approximate retention time of the test item. The peak decreased significantly or even disappeared in the second injection of the blank solution, suggesting that it was caused by carryover. It has to be noted that this carryover did not exceed 10% of the sample response and affected both standard and sample solutions. It has therefore been considered that its overall effect on the results was negligible.

The kinetics of the study have been determined to be consistent with that of a pseudo-first order reaction, as the graphs of log10 concentration versus time are straight lines.

It has been observed that the rate of hydrolysis increases with an increase in pH, with the test item being hydrolytically stable at pH 4.

Validity criteria fulfilled:
yes
Executive summary:

The hydrolytic stability of Ethoxy ethoxy ethyl acrylate (CAS No. 7328-17-8) was determined using a procedure designed to be compatible with Method C.7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

Duplicate samples (standard, sample and blank solutions) were analyzed by gas chromatography with flame ionization detection (GC-FID).

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 10 to 300 mg/L in 75:25 v/v acetonitrile:relevant buffer

solution. This was satisfactory with a goodness of fit coefficient (r2) of 1.000 being obtained for all three matrices. The kinetics of the study have been determined to be consistent with that of a pseudo-first order reaction, as the graphs of log10 concentration versus time are straight lines.

The estimated rate constants at 25 °C was not applicable (pH 4), 9.22 x 10-5 h-1 (pH 7) and 6.21 x 10-3 h-1 (pH 9). The coresponding half-lives at 25 °C >1 year (pH 4), 313 days (pH 7) and 4.65 days (pH 9). Based on these results, the rate of hydrolysis increases with an increase in pH, with Ethoxy ethoxy ethyl acrylate (CAS No. 7328-17-8) being hydrolytically stable at pH 4.

Description of key information

The estimated rate constants and half-lives at 25 °C of the test item are found at:

pH

Estimated rate constant at 25 °C

Estimated half-life at 25 °C

4

Not applicable

>1 year

7

9.22 x 10-5h-1

313 days

9

6.21 x 10-3h-1

4.65 days

Key value for chemical safety assessment

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

Additional information