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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:
From 18 March, 2016 to 30 September, 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
The main structure of the read-across substance is the same of the CJ313, only the salt form is different. However, this difference does not influence the toxicity of the CJ313. CJ313 contains Li/Na salt form and the read-across substances contains only Na salt. This will not lead to difference on the toxicity results.
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:
Identification: FAT 40032/G TE
Physical State/Appearance: Black powder
Batch: 43 (India)
Purity: 84.3%
Expiry: 03 February 2020
Storage Conditions: Approximately -20 °C, in the dark
Radiolabelling:
no
Analytical monitoring:
yes
Remarks:
The concentration of the sample solution was determined by high performance liquid chromatography (HPLC).
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:
- Buffer solution pH 4 : Citric acid 0.006 mol dmE-3, Sodium chloride 0.004 mol dmE-3, Sodium hydroxide 0.007 mol dmE-3.
- Buffer solution pH 7 : Disodium hydrogen orthophosphate (anhydrous) 0.003 mol dmE-3, Potassium dihydrogen orthophosphate 0.002 mol dmE-3, Sodium chloride 0.002mol dmE-3.
- Buffer solution pH 9 : Disodium tetraborate 0.001 mol dmE-3, Sodium chloride 0.002 mol dmE-3.
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 1
Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 144 hours.

Tier 2
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.
Duration:
144 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
0.01 g/L
Remarks:
Tier 1 - Preliminary test
Duration:
144 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
0.01 g/L
Remarks:
Tier 1 - Preliminary test
Duration:
144 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.01 g/L
Remarks:
Tier 1 - Preliminary test
Duration:
744 h
pH:
4
Temp.:
70 °C
Initial conc. measured:
0.01 g/L
Remarks:
Tier 2
Duration:
360 h
pH:
4
Temp.:
70 °C
Initial conc. measured:
0.01 g/L
Number of replicates:
two
Positive controls:
no
Negative controls:
no
Statistical methods:
None
Preliminary study:
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.

Preliminary pH 7 Test at 50.0 ± 0.5 ºC
Less than 10% hydrolysis after 5 days at 50 °C, equivalent to a half-life of greater than 1 year at 25 °C.

Preliminary pH 9 Test at 50.0 ± 0.5 ºC
Less than 10% hydrolysis after 5 days at 50 °C, equivalent to a half-life of greater than 1 year at 25 °C.
Test performance:
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 1
Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 144 hours.
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:
pH 4 at 50.0 ± 0.5 ºC
Slope = -5.12 x 10-4 (see Figure 1) kobs = 1.18 x 10-3 hour-1 t½ = 589 hours = 24.5 days
The extent of hydrolysis indicated that a further test (Tier 2) was required to estimate the rate constant and half-life at 25 °C.

pH 4 at 60.0 ± 0.5 ºC
Slope = -1.02 x 10-3 (see Figure 2) kobs = 2.34 x 10-3 hour-1 t½ = 296 hours

pH 4 at 70.0 ± 0.5 ºC
Slope = -2.16 x 10-3 (see Figure 3) kobs = 4.97 x 10-3 hour-1 t½ = 139 hours

pH 4 Arrhenius Data
From the graph of the above data, the rate constant and half-life at 25 °C have been estimated to be as follows:
k = 1.46 x 10-4 hour-1 t½ = 4.75 x 103 hours = 198 days
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 rate constant and estimated half-life at 25 °C of the test item are:
At pH 4 the rate constant was 1.46 x 10-4 h-1 at 25 °C
The estimated half life at pH 4 at 25 °C was 198 days.
The estimated half life at pH 7 at 25 °C was >1 year.
The estimated half life at pH 9 at 25 °C was >1 year.
Executive summary:

Assessment of hydrolytic stability was carried out 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.

The test substance was evaluated at pH 4 for 24h, 120 h, 144 h, 408 h, 552h and 744 h. For pH 7 and 9 the duration was 24h, 120 h and 144h. All tests were carried out at 50 °C. The concentration used was 0.01 g/L.

Based on the findings of the study,

The rate constant and estimated half-life at 25 °C of the test item are:

At pH 4 the rate constant was 1.46 x 10-4 h-1 at 25 °C

The estimated half life at pH 4 at 25 °C was 198 days.

The estimated half life at pH 7 at 25 °C was >1 year.

The estimated half life at pH 9 at 25 °C was >1 year.

Description of key information

FAT 40032/G was determined to be hydrolytically stable.

Key value for chemical safety assessment

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

Additional information

A key assessment of hydrolytic stability was carried out using a procedure designed to be compatible with EU Method C.7 and OECD Guideline 111. Based on the findings of the study, the test substance (FAT 40032/G) was 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 half-life of 198 days.