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Environmental fate & pathways

Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Principles of method if other than guideline:
None
GLP compliance:
yes
Specific details on test material used for the study:
None
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
The sample solutions were taken from the waterbath at various times and the pH of each solution recorded.
The concentration of the sample solution was determined by high performance liquid chromatography (HPLC).
Buffers:
The test system consisted of sterile buffer solutions at pH’s 4, 7 and 9.
Estimation method (if used):
None
Details on test conditions:
Performance of the Test
Preparation of the Test Solutions
Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 100 mg/L in the three buffer solutions.
The test solutions were split into individual vessels for each data point.
The solutions were shielded from light whilst maintained at the test temperature.

Preliminary Test / Tier
Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 144 hours.

Tier
Results from the Preliminary Test / Tier 1 showed it was necessary to undertake further testing at pH 4 with solutions being maintained at 60.0 ± 0.5 °C and 70.0 ± 0.5 °C, and extending the 50 °C test (Tier 1) to 744 hours.

Evaluation of Data
The response factors of the standard peak areas (unit peak area per mg/L) were calculated using the following equation:
Equation 1
STDSTDCR = RF

where:
RF = response factor for the standard solution
RSTD = peak area for the standard solution
CSTD = concentration for the standard solution (mg/L)
Each sample solution concentration (g/L) was calculated using the following equation:
Duration:
144 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
100 mg/L
Remarks:
Tier - 1 - Preliminary test
Duration:
744 h
pH:
4
Temp.:
70 °C
Initial conc. measured:
100 mg/L
Remarks:
Tier 2
Duration:
144 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
100 mg/L
Remarks:
Tier 1 - Preliminary test
Duration:
144 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
100 mg/L
Remarks:
Tier 1 - Preliminary test
Number of replicates:
two
Positive controls:
no
Negative controls:
no
Statistical methods:
None
Preliminary study:
None
Test performance:
None
Transformation products:
not measured
Details on hydrolysis and appearance of transformation product(s):
None
pH:
4
Temp.:
25 °C
Hydrolysis rate constant:
0 h-1
DT50:
198 d
Remarks on result:
other: Standard deviation not available
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: Standard deviation not available
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: Standard deviation not available
Other kinetic parameters:
None
Details on results:
None
Results with reference substance:
None

Tier 2

The mean peak areas relating to the standard and sample solutions are shown in the following tables:

pH 7 - 40.0 ± 0.5 °C Tier 2 Testing

Solution

Mean Peak Area

Standard 102 mg/L

8.6407 x 106

Standard 106 mg/L

9.0462 x 106

Initial Sample A, pH 4

8.5429 x 106

Initial Sample B, pH 4

8.5465 x 106

 Standard 104 mg/L, pH 4  8.7344 X 106
 Standard 104 mg/L, pH 4  8.7569 x 106
 71 hours Sample A, pH 4, 60 °C  7.0521 x 106
  71 hours Sample B, pH 4, 60 °C   7.0509 x 106
  71 hours Sample A, pH 4, 70 °C   5.8135 x 106
  71 hours Sample B, pH 4, 70 °C

 5.7857 x 106 

  Standard 100 mg/L, pH 4

 8.5041 x 106 

  Standard 102 mg/L, pH 4

 8.5285 x 106 

 192 Hours Sample A, pH 4, 60 ºC

 5.8968 x 106 

 192 Hours Sample B, pH 4, 60 ºC

 5.8591 x 106 

 192 Hours Sample A, pH 4, 70 ºC

 4.0395 x 106 

 192 Hours Sample B, pH 4, 70 ºC

 3.9644 x 106 

 Standard 99.8 mg/L, pH 4

8.2926 x 106 

 Standard 103 mg/L, pH 4

8.6209 x 106 

 192 Hours Sample A, pH 4, 60 ºC

5.2178 x 106 

 192 Hours Sample B, pH 4, 60 ºC

 5.2419 x 106 

 192 Hours Sample A, pH 4, 70 ºC

3.2039 x 106 

 192 Hours Sample B, pH 4, 70 ºC

3.1562 x 106 

 Standard 102 mg/L, pH 4

8.9607 x 106 

 Standard 108 mg/L, pH 4

 8.4690 x 106 

 240 Hours Sample A, pH 4, 60 ºC

 4.8335 x 106 

 240 Hours Sample B, pH 4, 60 ºC

 4.7509 x 106 

 240 Hours Sample A, pH 4, 70 ºC

 2.5438 x 106 

 240 Hours Sample B, pH 4, 70 ºC

 2.5137 x 106 

 Standard 102 mg/L, pH 4

 8.5285 x 106 

 Standard 101 mg/L, pH 4

 8.4646 x 106 

 312 Hours Sample A, pH 4, 60 ºC

 4.0104 x 106 

 312 Hours Sample B, pH 4, 60 ºC

 4.0426 x 106 

 312 Hours Sample A, pH 4, 60 ºC

 1.7564 x 106 

 312 Hours Sample B, pH 4, 60 ºC

 1.8029 x 106 

 Standard 101 mg/L, pH 4

 8.4756 x 106

 Standard 103 mg/L, pH 4

 8.7408 x 106

 360 Hours Sample A, pH 4, 60 ºC

 3.6122 x 106

 360 Hours Sample B, pH 4, 60 ºC

 3.6103 x 106

 360 Hours Sample A, pH 4, 60 ºC

 1.4099 x 106 

 360 Hours Sample B, pH 4, 60 ºC

  1.3736 x 106

Validity criteria fulfilled:
yes
Conclusions:
The estimated rate constant and half-lives at 25 °C of the test item are:
At pH 4 the estimated half-life at 25 °C was 198 days with estimated rate constant 0.000146
At pH 7 the estimated half-life at 25 °C was more than a year.
At pH 9 the estimated half-life at 25 °C was more than a year.
Executive summary:

The hydrolysis behaviour as a function of pH of FAT 40032/G has been evaluated according to OECD Guideline 111 and EU Method C.7.

The results are summarized below:

pH

Estimated rate constant (s-1) at 25 °C

Estimated half-life at 25 °C

4

1.46 x 10-6

198

7

-

> 1 year

9

-

> 1 year

 

 

Description of key information

The test substance FAT 40032/G has been determined to be hydrolytically stable, i.e., a half-life of greater than 1 year at 25 °C, at pH 7 and 9, whereas at pH 4 the estimated rate constant was 1.46 X 10 -6 with a half-life of 198 days.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 yr
at the temperature of:
25 °C

Additional information

The hydrolysis behaviour as a function of pH of FAT 40032/G has been evaluated according to OECD Guideline 111 and EU Method C.7.

The results are summarized below:

pH

Estimated rate constant (s-1) at 25 °C

Estimated half-life at 25 °C

4

1.46 x 10-6

198

7

-

> 1 year

9

-

> 1 year