Tetrasodium [2-({4-fluoro-6-[(2-{[4-fluoro-6-({5-(hydroxykappaO)-6-[(2-{[2-(hydroxy-kappaO)-5-sulfophenyl] diazenyl-kappaN1}-4,5-dimethoxyphenyl) diazenyl-kappaN2]-7-sulfo-2-naphthyl} amino)-1,3,5-triazin-2-yl] amino} propyl) amino]-1,3,5-triazin-2-yl} amino) benzene-1,4- disulfonato(6-)] cuprate(4-)

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experiment start date - 09 June 2006; Experiment completion date - 11 August 2006;
Study completion date - 05 December 2006

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)

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)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Before and after incubation, aliquots of the test solutions at each pH value were analysed without dilution by measuring the UVA/IS signal of FAT 40825/A after HPLC separation of the injected sample solution.

Buffers:

Buffer pH 4: Biphthalate, Baker, Art. No. 5657
Buffer pH 7: Phosphate, Baker, Art. No. 5656
Buffer pH 9: Borate, Baker, Art. No. 7145

Estimation method (if used):

no data

Details on test conditions:

no data

Duration:

6.5 h

pH:

4

Temp.:

60 °C

Initial conc. measured:

101.3 mg/L

Duration:

11 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

98 mg/L

Duration:

31 h

pH:

4

Temp.:

40 °C

Initial conc. measured:

89.3 mg/L

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

>= 98.73 - <= 101.64 mg/L

Duration:

11 h

pH:

9

Temp.:

70 °C

Initial conc. measured:

111.9 mg/L

Duration:

31 h

pH:

9

Temp.:

60 °C

Initial conc. measured:

106.5 mg/L

Duration:

141.8 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

120.8 mg/L

Number of replicates:

2 replicates

Positive controls:

not specified

Negative controls:

not specified

Statistical methods:

no data

Preliminary study:

According to the guideline, a preliminary hydrolysis tests was performed at 50.0 °C ± 0.1 °C at pH 4.0, pH 7.0 and pH 9.0, each. Aliquots of each test solution were analysed at the beginning and after 2.4 and 120 hours using the analytical method as described later in this report. Due to the instability of the test item found in the preliminary test at 50.0 °C, further hydrolysis tests were performed at 40 °C, 50 °C and 60 °C in the buffered test solution at pH 4.0 and at 50 °C, 60 °C and 70 °C in the buffered test solution at pH 9.0. At pH 7.0 the test item was found to be stable at 50 °C. Therefore, no further testing was performed at this pH-value.

Test performance:

The test item was dissolved in an aqueous solution at a specific pH-value (pH 4.0, 7.0 and 9.0) and was incubated at a specific temperature with a maximum deviation of ± 0.5 °C and then kept constant within ± 0.1 °C. The concentration of the test item was determined as a function of time, using a suitable analytical method. In case of decreasing concentrations, the logarithms of the concentrations are plotted against time (log10 (ct)). If the plot is a straight line, the reaction is considered to be of (pseudo-) first order. The rate constant and the half-life time is then calculated using the slope. Otherwise, the rate constant can be estimated by the use of the Arrhenius relationship.

Transformation products:

not specified

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

no data

pH:

4

Temp.:

25 °C

DT50:

68 h

Type:

(pseudo-)first order (= half-life)

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

pH:

9

Temp.:

25 °C

DT50:

149 d

Type:

(pseudo-)first order (= half-life)

Other kinetic parameters:

no data

Details on results:

HYDROLYSIS AT 50.0 °C:
pH 7.0:
The results of pH 7.0 showed no significant degradation of FAT 40825/A at 50 °C. According to the EEC Directive 92/69, Section C.7, it can be concluded, that the estimated half-life time is higher than one year under representative environmental conditions (25 °C). Therefore, FAT 40825/A can be considered to be hydrolytically stable at pH 7.0 and no further testing was necessary at this pH-value.

pH 4.0:
The results of the preliminary test show, that FAT 40825/A is not stable at pH 4.0. Therefore the test at 50 °C was repeated in the range of 20 % to 70% degradation. The linear plots prove that the hydrolysis reaction is of pseudo first order in the range from 20 % to 70 % hydrolysis at pH 4.0. The half-life time of FAT 40825/A at 50 °C and pH 4.0 was calculated to be 6 hours.

pH 9.0:
The results of the preliminary test show, that FAT 40825/A is not stable at pH 9.0. Therefore the test at 50 °C was repeated in the range of 20 % to 70% degradation. The linear plots prove that the hydrolysis reaction is of pseudo first order in the range from 20 % to 70 % hydrolysis at pH 9.0. The half-life time of FAT 40825/A at 50 °C and pH 9.0 was calculated to be 81 hours (3 days).

Validity criteria fulfilled:

yes

Conclusions:

FAT 40825/A at pH 4.0 has a half-life time of 68 hours (3 days) at 25 °C.
FAT 40825/A is stable at pH 7.0. Its half-life time is longer than one year at 25 °C.
FAT 40825/A at pH 9.0 has a half-life time of 3576 hours (149 days) at 25 °C.

Executive summary:

The hydrolysis of the test item was performed at 50.0 °C ± 0.1 °C at each of pH 4.0, pH 7.0 and pH 9.0.

FAT 40825/A was found to be stable at pH 7.0 and 50 °C. Therefore, no further testing was performed at this pH-value.

FAT 40825/A was not stable at pH 4.0 and at pH 9.0, further testing was performed at elevated temperatures in order to calculate the rate constant (k25) and the half-life time of the hydrolysis at pH 7.0, pH 9.0 at 25 °C. The results are summarised below:

FAT 40825/A at pH 4.0 has a half-life time of 68 hours (3 days) at 25 °C.

FAT 40825/A is stable at pH 7.0. Its half-life time is longer than one year at 25 °C.

FAT 40825/A at pH 9.0 has a half-life time of 3576 hours (149 days) at 25 °C.

Description of key information

The substance is stable at pH 7 (half-life >1 year), at pH4 the substance was unstable (half-life of 68 hours (3 days) at 25 °C) and at pH 9 a lower degradation rate (3576 hours (149 days) at 25 °C) was found.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

The hydrolysis of the test item was performed at 50.0 °C ± 0.1 °C at each of pH 4.0, pH 7.0 and pH 9.0.

FAT 40825/A was found to be stable at pH 7.0 and 50 °C. Therefore, no further testing was performed at this pH-value.

FAT 40825/A was not stable at pH 4.0 and at pH 9.0, further testing was performed at elevated temperatures in order to calculate the rate constant (k25) and the half-life time of the hydrolysis at pH 7.0, pH 9.0 at 25 °C. The results are summarised below:

FAT 40825/A at pH 4.0 has a half-life time of 68 hours (3 days) at 25 °C.

FAT 40825/A is stable at pH 7.0. Its half-life time is longer than one year at 25 °C.

FAT 40825/A at pH 9.0 has a half-life time of 3576 hours (149 days) at 25 °C.