3,10-diamino-6,13-dichloro-2-((6-(((4-(1,1-dimethylethyl)phenyl)sulfonyl)amino)-2-naphthalenyl)sulfonyl)-4,11-triphenodioxazinedisulfonic acid, lithium potassium sodium salt

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

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)

Version / remarks:

adopted May 12, 1981

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

December 1992

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Not relevant as not performed (because no test item was detectable in the sample solutions).

Buffers:

- pH: 4.0, 7.0 & 9.0
- Composition of buffer:
Buffer pH 4, Biphthalate (Art. 5657 - Baker)
Buffer pH 7, Phosphate (Art. 5656 - Baker)
Buffer pH 9, Borate (Art. 7145 - Baker)
The buffer solutions were sterilized for 25 minutes in an autoclave prior to first use. Nitrogen was passed through the buffer solutions for 5 minutes except when freshly sterilized.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: All glassware, which must be inert in the pH range applied, were rinsed with sterile buffer. The hydrolysis was carried out in flasks which were stoppered or sealed with an inert material (e.g. PTFE).
- Sterilisation method: The buffer solutions were sterilized for 25 minutes in an autoclave prior to first use. Nitrogen was passed through the buffer solutions for 5 minutes except when freshly sterilized.

TEST MEDIUM
- Volume used/treatment
- Kind and purity of water:
- Preparation of test medium: The test item was dissolved in the buffer solutions and incubated at 50 °C with the water bath kept constant at ± 0.1 °C, usually. The concentration of the test item was determined as a function of time at each pH.

Preparation of the Test Solution pH 4.0
A 13.43 mg sample of BLUE GS 5664.80 were dissolved in 2 ml dimethylformamide. This mixture was made up to 100 ml with buffer solution (pH 4.0). The solution was ultrasonified for 10 minutes and submitted to a 0.2 μm filtration. To obtain a test solution of not more than half the water solubility, the solution was diluted 1 :1 with the respective buffer and again submitted to a 0.45 μm and 0.2 μm filtration. Two aliquots of this test solution of approximately 50 ml each were transferred into 50 ml Erlenmeyer flasks in order to perform a duplicate test.

Preparation of the Test Solution pH 7.0
A 11.87 mg sample of BLUE GS 5664.80 were dissolved in 2 ml dimethylformamide. This mixture was made up to 100 ml with buffer solution (pH 7.0). The solution was ultrasonified for 1 O minutes and submitted to a 0.2 μm filtration. To obtain a test solution of not more than half the water solubility, the solution was diluted 1 :1 with the respective buffer and again submitted to a 0.45 μm and 0.2 μm filtration. Two aliquots of this test solution of approximately 50 ml each were transferred into 50 ml Erlenmeyer flasks in order to perform a duplicate test.

Preparation of the Test Solution pH 9.0
A 13.87 mg sample of BLUE GS 5664.80 were dissolved in 2 ml dimethylformamide. This mixture was made up to 100 ml with buffer solution (pH 9.0). The solution was ultrasonified for 10 minutes and submitted to a 0.2 μm filtration. To obtain a test solution of not more than half the water solubility, the solution was diluted 1 :1 with the respective buffer and again submitted to a 0.45 μm and 0.2 μm filtration. Two aliquots of this test solution of approximately 50 ml each were transferred into 50 ml Erlenmeyer flasks in order to perform a duplicate test.

pH:

4

Temp.:

50 °C

Remarks:

No test item was detectable in the sample solutions because its solubility was very low (peaks obtained were too small to allow quantification)

pH:

7

Temp.:

50 °C

Remarks:

No test item was detectable in the sample solutions because its solubility was very low (peaks obtained were too small to allow quantification)

pH:

9

Temp.:

50 °C

Remarks:

No test item was detectable in the sample solutions because its solubility was very low (peaks obtained were too small to allow quantification)

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Statistical methods:

Not used

Transformation products:

not measured

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Details on results:

The solubility of BLUE GS 5664.80 in the buffer solutions pH 4.0, pH 7.0 and pH 9.0 was very low. It was not possible to increase the solubility of the test item with the use of dimethylformamide as solubilizer. Peaks obtained, if any, were too small to allow
quantification or even to follow a degradation curve.
The test item shows no significant solubility in the different solvent systems. Therefore, no further testing could be performed with BLUE GS 5664.80 at pH 4.0, pH 7.0 and pH 9.0.

Results with reference substance:

none

Validity criteria fulfilled:

yes

Conclusions:

Based on results of the preliminary test, BLUE GS 5664.80 is considered hydrolytically stable with DT50 at 25°C > 1 year.

Executive summary:

The hydrolysis determination of BLUE GS 5664.80 at different pH values was based on the OECD Guideline No. 111, "Hydrolysis as a Function of pH"; adopted May 12, 1981 and on the EEC Directive 92/69, Section C.7, "Abiotic Degradation: Hydrolysis as a Function of pH", L383 A, December 1992.

The solubility of BLUE GS 5664.80 in the buffer solutions pH 4.0, pH 7.0 and pH 9.0 was very low. It was not possible to increase the solubility of the test item with the use of dimethylformamide as solubilizer. Peaks obtained, if any, were too small to allow quantification or even to follow a degradation curve.

The test item shows no significant solubility in the different solvent systems. Therefore, no further testing could be performed with BLUE GS 5664.80 at pH 4.0, pH 7.0 and pH 9.0.

The linearity of the analytical method was proved in the concentration range from 0.12792 μg/ml to 63.96 μg/ml.

As detailed in OECD TG 111: "the preliminary test is performed at 50 ± 0.5°C and pH 4.0, 7.0 and 9.0. If less than 10% of hydrolysis is observed after 5 days (t1/2 at 25°C > 1 year), the test substance is considered hydrolytically stable and, normally, no additional testing is required. The analytical method must be sufficiently precise and sensitive to detect a reduction of 10 per cent in the initial concentration."

Based on results of the preliminary test, BLUE GS 5664.80 is therefore considered hydrolytically stable with DT50 at 25°C > 1 year.

Description of key information

As detailed in OECD TG 111: "the preliminary test is performed at 50 ± 0.5°C and pH 4.0, 7.0 and 9.0. If less than 10% of hydrolysis is observed after 5 days (t1/2 at 25°C > 1 year), the test substance is considered hydrolytically stable and, normally, no additional testing is required. The analytical method must be sufficiently precise and sensitive to detect a reduction of 10 per cent in the initial concentration."

Based on results of the preliminary test (OECD TG 111 and GLP), BLUE GS 5664.80 is therefore considered hydrolytically stable with DT50 at 25°C > 1 year.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C