Pentasodium 4-amino-6-[[5-[(4-amino-6-chloro-1,3,5-triazin-2-yl)amino]-2-sulphonatophenyl]azo]-3-[(2,5-disulphonatophenyl)azo]-5-hydroxynaphthalene-2,7-disulphonate

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

None

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The analytical standards for the quantification in this study were prepared using the test substance.

Stock Solutions:
17.2 mg of FAT 45168/A were dissolved in 100 ml of a mixture of deion. water / acetonitrile (95/5, v/v) to prepare the first stock solution of 172 µg/ml FAT 45168/A.
15.0 mg of FAT 45168/A were dissolved in 100 ml of a mixture of deion. water / acetonitrile (95/5, v/v) to prepare the second stock solution of 150 µg/ml FAT 45168/A.

Standard Solutions:
Calculated volumes of the stock solution obtained were diluted with a mixture of deion. water / acetonitrile (95/5, v/v) to obtain standard solutions in the range from 22.5 µg/ml to 120 µg/ml FAT 45168/A.

Sample Preparation:
20 µl aliquots of the test solutions were analysed after incubation without dilution by measuring the VIS signal of FAT 45'168/A after HPLC separation of the injected sample solution.

Buffers:

Buffer solutions with the following concentrations were used for experiments:
pH 4.0: 0.40 vol % 0.1 M NaOH
50.00 vol% 0.1 M potassium biphthalate
49.60 vol% double distilled water

pH 7.0: 29.63 vol%0.1 M NaOH
50.00 vol% 0.1 M monopotassium phosphate
20.37 vol% double distilled water

pH 9.0: 21.30 vol% 0.1 M NaOH
50.00 vol% 0.1 M boric acid
28.70 vol% double distilled water
The pH of each buffer solution was checked with a calibrated pH meter at required temperature to a precision of at least ±0.1.

Estimation method (if used):

Not available

Details on test conditions:

PERFORMANCE OF THE TEST
The hydrolysis tests were performed at 50 ± 0.1 °C at pH 4.0, pH 7.0, and pH 9.0, each. Aliquots of each test solution were analysed in time intervals using the analytical method as described later in this report.

Further hydrolysis tests were performed at 60 °C and 70 °C in the buffered test solution at pH 4.0, due to the instability of the test article found in the hydrolysis tests at 50 °C.

Preparation of the Test Solutions
Aliquots of FAT 45168/A (weight ranged from 10.2 mg to 10.5 mg) were dissolved in 100 ml buffer solution pH 4.0, pH 7.0, and pH 9.0, respectively. 50 ml aliquots of this test solutions prepared were used for the performance of the hydrolysis tests in duplicate at 50 ± 0.1 °C. Aliquots of FAT 45168/A (weight ranged from 20.1 mg to 20.2 mg) were dissolved in 200 ml buffer solution pH4.0 respectively. 100 ml aliquots of this test solutions prepared were used for the performance of the hydrolysis tests in duplicate at 60 °C and 70 °C.

Duration:

5 d

Temp.:

50 °C

Number of replicates:

duplicates

Positive controls:

not specified

Negative controls:

not specified

Statistical methods:

Not available

Preliminary study:

Not available

Test performance:

Not available

Transformation products:

not specified

Details on hydrolysis and appearance of transformation product(s):

Not available

Key result

pH:

4

Temp.:

25 °C

DT50:

ca. 100 d

Type:

not specified

Details on results:

HYDROLYSIS AT 50 °C
The hydrolysis test was performed with FAT 45'168/A at 50 ± 0.1 °C at each of pH 4.0, pH 7.0, and pH 9.0, respectively, in duplicate. The FAT 45'168/A test solutions were thermostated to 50 °C and analysed in time intervals.

The hydrolysis reactions of FAT 45168/A at 50±0.1 °C and at pH 7.0 and pH 9.0, respectively were determined to be <10 %. The half-life times of FAT 45168/A at this pH range were estimated to be more than one year at 25 °C. Therefore according to the guidelines no further testing was performed at pH 7.0 and pH 9.0

In conclusion, the half-life time of FAT 45168/A at pH 4.0 was estimated to be shorter than one year and longer than one day at 25 °C. Therefore, according to the guidelines advanced testing of FAT 45'168/A was necessary to determine the rate constant (k25) of the FAT 45'168/A hydrolysis reaction at pH 4.0.
The obtained data was plotted at In q versus t. The linear plots prove that the hydrolysis reaction of FAT 45168/A is pseudo first order in the range from 20 to 70 % hydrolysis at pH 4.0. The reaction rate constant k for pH 4.0 was calculated by regression analysis.
The half-life time of the observed hydrolysis reaction of FAT 45168/A at 50 °C and pH 4.0 was calculated to be 389 hours.

HYDROLYSIS AT PH 4.0 AND DIFFERENT TEMPERATURES
The hydrolysis reaction at pH 4.0 is relative slow. Therefore, the further hydrolysis test at pH 4.0 was performed at 60 and 70 °C in duplicate. Each buffered test solution was analysed in time intervals.
The obtained linear plot of each sample prove that the hydrolysis reaction is pseudo first order at 60 and 70 °C. The reaction rate constant k was calculated by regression analysis.
The half-life time of the observed hydrolysis reaction of FAT 45168/A at 60 °C and pH 4.0 was calculated to be 162 hours.
The half-life time of the observed hydrolysis reaction of FAT 45168/A at 70 °C and pH 4.0 was calculated to be 106 hours.

HALF-LIFE TIME AT 25 °C
The half-life time of the hydrolysis reaction of FAT 45168/A at 25 °C and pH 4.0 was estimated to be about 100 days.

None

Validity criteria fulfilled:

yes

Conclusions:

The hydrolysis reaction of FAT 45168/A at pH 4.0 and 25 °C was estimated to be relative slow (t1/2 (25 °C) = about 100 days).

Executive summary:

The hydrolysis of the test article was performed at 50 ± 0.1 °C at each of pH 4.0, pH 7.0, and pH 9.0.

The results of pH 7.0 and pH 9.0 showed no significant degradation of FAT 45168/A. The percentage of the hydrolysis at pH 7.0 and pH 9.0 respectively was found to be less than 10 % after 5 days incubation at 50 ± 0.1 °C. In conclusion, FAT 45168/A was considered to be hydrolytically stable at pH 7.0 and pH 9.0. Therefore, according to the guidelines no further testing of FAT 45'168/A was performed at pH 7.0 and pH 9.0.

The results at pH 4.0 showed that FAT 45'168/A is not stable at this pH range. The percentage of hydrolysis at pH 4.0 was found to be more than 10 % after 5 days. Therefore, according to the guidelines advanced testing of FAT 45168/A was performed to determine the rate constant (K25) of the FAT 45168/A hydrolysis reaction at pH 4.0. As a result of all observations, it can be stated that the hydrolysis reaction of FAT 45168/A at pH 4.0 and 25 °C was estimated to be relative slow (t1/2(25 °C) = about 100 days).

The activation energy of FAT 45168/A at pH4.0 was estimated to be 60.1 kJ/mol and the reaction rate constant (K) of FAT 45168/A at pH 4.0 was estimated to be 2.9 10(-4) per hour.

Reference 2

Endpoint:

hydrolysis

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For a detailed justification of the read across, please refer to chapter 13.

Reason / purpose for cross-reference:

read-across source

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The analytical standards for the quantification in this study were prepared using the test substance.

Stock Solutions:
17.2 mg of FAT 45'168/A were dissolved in 100 ml of a mixture of deion. water / acetonitrile (95/5, v/v) to prepare the first stock solution of 172 µg/ml FAT 45'168/A.
15.0 mg of FAT 45'168/A were dissolved in 100 ml of a mixture of deion. water / acetonitrile (95/5, v/v) to prepare the second stock solution of 150 µg/ml FAT 45'168/A.

Standard Solutions:
Calculated volumes of the stock solution obtained were diluted with a mixture of deion. water / acetonitrile (95/5, v/v) to obtain standard solutions in the range from 22.5 µg/ml to 120 µg/ml FAT 45'168/A.

Sample Preparation:
20 µl aliquots of the test solutions were analysed after incubation without dilution by measuring the VIS signal of FAT 45'168/A after HPLC separation of the injected sample solution.

Buffers:

Buffer solutions with the following concentrations were used for experiments:
pH 4.0: 0.40 vol % 0.1 M NaOH
50.00 vol% 0.1 M potassium biphthalate
49.60 vol% double distilled water

pH 7.0: 29.63 vol%0.1 M NaOH
50.00 vol% 0.1 M monopotassium phosphate
20.37 vol% double distilled water

pH 9.0: 21.30 vol% 0.1 M NaOH
50.00 vol% 0.1 M boric acid
28.70 vol% double distilled water
The pH of each buffer solution was checked with a calibrated pH meter at required temperature to a precision of at least ±0.1.

Details on test conditions:

PERFORMANCE OF THE TEST
The hydrolysis tests were performed at 50 ± 0.1 °C at pH 4.0, pH 7.0, and pH 9.0, each. Aliquots of each test solution were analysed in time intervals using the analytical method as described later in this report.

Further hydrolysis tests were performed at 60 °C and 70 °C in the buffered test solution at pH 4.0, due to the instability of the test article found in the hydrolysis tests at 50 °C.

Preparation of the Test Solutions
Aliquots of FAT 45'168/A (weight ranged from 10.2 mg to 10.5 mg) were dissolved in 100 ml buffer solution pH 4.0, pH 7.0, and pH 9.0, respectively. 50 ml aliquots of this test solutions prepared were used for the performance of the hydrolysis tests in duplicate at 50 °C ± 0.1 °C. Aliquots of FAT 45'168/A (weight ranged from 20.1 mg to 20.2 mg) were dissolved in 200 ml buffer solution pH4.0 respectively. 100 ml aliquots of this test solutions prepared were used for the performance of the hydrolysis tests in duplicate at 60 °C and 70 °C.

Duration:

5 d

Temp.:

50 °C

Number of replicates:

duplicates

Positive controls:

not specified

Negative controls:

not specified

Statistical methods:

Not available

Preliminary study:

Not available

Test performance:

Not available

Transformation products:

not specified

Details on hydrolysis and appearance of transformation product(s):

Not available

Key result

pH:

4

Temp.:

25 °C

DT50:

ca. 100 d

Type:

not specified

Details on results:

HYDROLYSIS AT 50 °C
The hydrolysis test was performed with FAT 45'168/A at 50 ± 0.1 °C at each of pH 4.0, pH 7.0, and pH 9.0, respectively, in duplicate. The FAT 45'168/A test solutions were thermostated to 50 °C and analysed in time intervals.

The hydrolysis reactions of FAT 45'168/A at 50 ± 0.1 °C and at pH 7.0 and pH 9.0, respectively were determined to be <10 %. The half-life times of FAT 45'168/A at this pH range were estimated to be more than one year at 25 °C. Therefore according to the guidelines no further testing was performed at pH 7.0 and pH 9.0

In conclusion, the half-life time of FAT 45'168/A at pH 4.0 was estimated to be shorter than one year and longer than one day at 25 °C. Therefore, according to the guidelines advanced testing of FAT 45'168/A was necessary to determine the rate constant (k25) of the FAT 45'168/A hydrolysis reaction at pH 4.0.
The obtained data was plotted at In q versus t. The linear plots prove that the hydrolysis reaction of FAT 45'168/A is pseudo first order in the range from 20 to 70 % hydrolysis at pH 4.0. The reaction rate constant k for pH 4.0 was calculated by regression analysis.
The half-life time of the observed hydrolysis reaction of FAT 45'168/A at 50 °C and pH 4.0 was calculated to be 389 hours.

HYDROLYSIS AT PH 4.0 AND DIFFERENT TEMPERATURES
The hydrolysis reaction at pH 4.0 is relative slow. Therefore, the further hydrolysis test at pH 4.0 was performed at 60 and 70 °C in duplicate. Each buffered test solution was analysed in time intervals.
The obtained linear plot of each sample prove that the hydrolysis reaction is pseudo first order at 60 and 70 °C. The reaction rate constant k was calculated by regression analysis.
The half-life time of the observed hydrolysis reaction of FAT 45'168/A at 60 °C and pH 4.0 was calculated to be 162 hours.
The half-life time of the observed hydrolysis reaction of FAT 45'168/A at 70 °C and pH 4.0 was calculated to be 106 hours.

HALF-LIFE TIME AT 25 °C
The half-life time of the hydrolysis reaction of FAT 45'168/A at 25 °C and pH 4.0 was estimated to be about 100 days.

None

Validity criteria fulfilled:

yes

Conclusions:

The hydrolysis reaction of source chemical, FAT 45168/A at pH 4.0 and 25 °C was estimated to be relative slow (t1/2 (25 °C) = about 100 days).

Executive summary:

The hydrolysis assessment of the source chemical, FAT 45168/A was performed at 50 ± 0.1 °C at each of pH 4.0, pH 7.0, and pH 9.0.

The results of pH 7.0 and pH 9.0 showed no significant degradation of FAT 45168/A. The percentage of the hydrolysis at pH 7.0 and pH 9.0 respectively was found to be less than 10 % after 5 days incubation at 50 ± 0.1 °C. In conclusion, FAT 45168/A was considered to be hydrolytically stable at pH 7.0 and pH 9.0. Therefore, according to the guidelines no further testing of FAT 45168/A was performed at pH 7.0 and pH 9.0.

The results at pH 4.0 showed that FAT 45168/A is not stable at this pH range. The percentage of hydrolysis at pH 4.0 was found to be more than 10 % after 5 days. Therefore, according to the guidelines advanced testing of FAT 45168/A was performed to determine the rate constant (K25) of the FAT 45168/A hydrolysis reaction at pH 4.0. As a result of all observations, it can be stated that the hydrolysis reaction of FAT 45168/A at pH 4.0 and 25 °C was estimated to be relative slow (t1/2(25 °C) = about 100 days).

The activation energy of FAT 45168/A at pH4.0 was estimated to be 60.1 kJ/mol and the reaction rate constant (K) of FAT 45168/A at pH 4.0 was estimated to be 2.9 10(-4) per hour.

Description of key information

A study was performed to measure the hydrolysis of the source chemical FAT 45168/A according to OECD guideline 111 at 50 ± 0.1 °C at each of pH 4.0, pH 7.0, and pH 9.0. The results of pH 7.0 and pH 9.0 showed no significant degradation of FAT 45168/A. The percentage of the hydrolysis at pH 7.0 and pH 9.0 respectively was found to be less than 10 % after 5 days incubation at 50 ± 0.1 °C. In conclusion, FAT 45168/A was considered to be hydrolytically stable at pH 7.0 and pH 9.0. Therefore, according to the guidelines no further testing of FAT 45168/A was performed at pH 7.0 and pH 9.0. The results at pH 4.0 showed that FAT 45168/A is not stable at this pH range. The percentage of hydrolysis at pH 4.0 was found to be more than 10 % after 5 days. Therefore, according to the guidelines advanced testing of FAT 45168/A was performed to determine the rate constant (K25) of the FAT 45168/A hydrolysis reaction at pH 4.0. As a result of all observations, it can be stated that the hydrolysis reaction of FAT 45168/A at pH 4.0 and 25 °C was estimated to be relative slow (t1/2 (25 °C) = about 100 days). The activation energy of FAT 45168/A at pH 4.0 was estimated to be 60.1 kJ/mol and the reaction rate constant (K) of FAT 45168/A at pH 4.0 was estimated to be 2.9 10E-4 per hour.

Key value for chemical safety assessment

Half-life for hydrolysis:

100 d

at the temperature of:

25 °C