Reaction mass of Tetrasodium 2-[{4-[{4-[(4-amino-6-chloro-1,3,5-triazin-2-yl)amino]-5-sulfonatonaphthalen-1-yl}diazenyl]-7-sulfonatonaphthalen-1-yl}diazenyl]benzene-1,4-disulfonate and Tetrasodium 2-[{4-[{4-[(4-amino-6-chloro-1,3,5-triazin-2-yl)amino]-5-sulfonatonaphthalen-1-yl}diazenyl]-6-sulfonatonaphthalen-1-yl}diazenyl]benzene-1,4-disulfonate

Hydrolysis

Link to relevant study record(s)

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 10^6
Standard 106 mg/L	9.0462 x 10^6
Initial Sample A, pH 4	8.5429 x 10^6
Initial Sample B, pH 4	8.5465 x 10^6
Standard 104 mg/L, pH 4	8.7344 X 10^6
Standard 104 mg/L, pH 4	8.7569 x 10^6
71 hours Sample A, pH 4, 60 °C	7.0521 x 10^6
71 hours Sample B, pH 4, 60 °C	7.0509 x 10^6
71 hours Sample A, pH 4, 70 °C	5.8135 x 10^6
71 hours Sample B, pH 4, 70 °C	5.7857 x 10^6
Standard 100 mg/L, pH 4	8.5041 x 10^6
Standard 102 mg/L, pH 4	8.5285 x 10^6
192 Hours Sample A, pH 4, 60 ºC	5.8968 x 10^6
192 Hours Sample B, pH 4, 60 ºC	5.8591 x 10^6
192 Hours Sample A, pH 4, 70 ºC	4.0395 x 10^6
192 Hours Sample B, pH 4, 70 ºC	3.9644 x 10^6
Standard 99.8 mg/L, pH 4	8.2926 x 10^6
Standard 103 mg/L, pH 4	8.6209 x 10^6
192 Hours Sample A, pH 4, 60 ºC	5.2178 x 10^6
192 Hours Sample B, pH 4, 60 ºC	5.2419 x 10^6
192 Hours Sample A, pH 4, 70 ºC	3.2039 x 10^6
192 Hours Sample B, pH 4, 70 ºC	3.1562 x 10^6
Standard 102 mg/L, pH 4	8.9607 x 10^6
Standard 108 mg/L, pH 4	8.4690 x 10^6
240 Hours Sample A, pH 4, 60 ºC	4.8335 x 10^6
240 Hours Sample B, pH 4, 60 ºC	4.7509 x 10^6
240 Hours Sample A, pH 4, 70 ºC	2.5438 x 10^6
240 Hours Sample B, pH 4, 70 ºC	2.5137 x 10^6
Standard 102 mg/L, pH 4	8.5285 x 10^6
Standard 101 mg/L, pH 4	8.4646 x 10^6
312 Hours Sample A, pH 4, 60 ºC	4.0104 x 10^6
312 Hours Sample B, pH 4, 60 ºC	4.0426 x 10^6
312 Hours Sample A, pH 4, 60 ºC	1.7564 x 10^6
312 Hours Sample B, pH 4, 60 ºC	1.8029 x 10^6
Standard 101 mg/L, pH 4	8.4756 x 10^6
Standard 103 mg/L, pH 4	8.7408 x 10^6
360 Hours Sample A, pH 4, 60 ºC	3.6122 x 10^6
360 Hours Sample B, pH 4, 60 ºC	3.6103 x 10^6
360 Hours Sample A, pH 4, 60 ºC	1.4099 x 10^6
360 Hours Sample B, pH 4, 60 ºC	1.3736 x 10^6

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