Benzenesulfonic acid, 2-[2-[5-(aminocarbonyl)-1-ethyl-1,6-dihydro-2-hydroxy-4-methyl-6-oxo-3-pyridinyl]diazenyl]-4-[[4-chloro-6-[[4-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]amino]-1,3,5-triazin-2-yl]amino]-, sodium salt (1:2)

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07 April 1993 to 20 April 1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to EU test guidance in compliance with GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Details on test material:

See below

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not applicable.

Radiolabelling:

no

Study design

Analytical monitoring:

yes

Details on sampling:

Sample Preparation
Direct injection of the test solutions was possible

Buffers:

pH 4 buffer solution (citric acid - monohydrate)
pH 7 buffer solution (potassiumdihydrogen phosphate)

Details on test conditions:

Choice of Concentration
The optimal concentration of test substance required for the HPLC analysis is about 200 mg/l. This value is less than the solubility in water (217 g/l) and thus satisfies the requirements of the guidelines.

Preparation of Test Samples
Solutions of the test substance were prepared by weighing ca. 20 mg of the test substance in a 100 ml volumetric flasks and dissolving in the relevant buffer.
The time between dissolution of the test sample and placing it into the thermostatic water bath (thermostated at the required hydrolysis temperature) was kept as short as possible.

Hydrolysis Test Procedure
The flask containing the hydrolysis mixture was placed in a water bath set thermostatically at the prescribed temperature for the time specified. Thereafter it was cooled immediately. A sample was taken and HPLC analysis of the unhydrolysed test substance (main compound) performed without delay.

Duration of test

Duration of test 1

Duration:

5 d

pH:

4

Temp.:

50

Initial conc. measured:

195.5 mg/L

Duration of test 2

Duration:

5 d

pH:

7

Temp.:

50

Initial conc. measured:

206.7 mg/L

Duration of test 3

Duration:

22.67 h

pH:

7

Temp.:

50

Initial conc. measured:

188.46 mg/L

Duration of test 4

Duration:

5.03 h

pH:

7

Temp.:

60

Initial conc. measured:

202.48 mg/L

Duration of test 5

Duration:

1.97 h

pH:

7

Temp.:

70

Initial conc. measured:

197.42 mg/L

Number of replicates:

2

Positive controls:

not specified

Negative controls:

not specified

Statistical methods:

The calculation standards used in the tests were freshly prepared solutions of the test substance in the relevant buffer.
The initial concentrations (c(0)) of the test substance were calculated from the sample weights.
c(t) =
The concentrations during the test process (c(t)) were calculated from the HPLC peak areas of the main component using the formula:
c(t) = c(Standard) * Peak Area(Sample) / Peak Area (Standard)

Results and discussion

Preliminary study:

The decomposition at pH 4 is less than 10 % after 5 days, thus making further tests unnecessary. The test substance may be considered hydrolytically stable at pH 4 according to the guideline. Therefore the half-life period, at 25 °C, may be estimated as greater than one year. The preliminary tests at pH 7 indicate that an examination of the linearity of the hydrolysis kinetics.

Test performance:

The test performed within the expected parameters. See below for results table. The substance is stable to hydrolysis at pH4, hydrolyses slowly at pH7 and rapidly at pH9.

Transformation products:

not measured

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

Not measured

Dissipation DT50 of parent compound

Dissipation DT50 of parent compound 1

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

other: prelimary test

Dissipation DT50 of parent compound 2

pH:

7

Temp.:

25 °C

DT50:

10.4 d

Remarks on result:

other: extrapolated from the results of test 1 and 3

Dissipation DT50 of parent compound 3

pH:

9

Temp.:

25 °C

DT50:

< 1 d

Remarks on result:

other: derived from hydrolysis investigations with substances of the same class

Details on results:

Test 1 showed an approximately linear relationship between log(c(t)/c(0)) and t. As a consequence the analyses in the guidelines described as Test 3 were performed using test temperatures of 60 °C and 70 °C.
The reaction rate constant and the resulting half-life period at 25 °C and pH 7 are determined by extrapolating the results of tests 1 and 3 using the Arrhenius equation.

Any other information on results incl. tables

Results of Analyses performed at pH 7

Temp. (⁰C)	Kobs(h^-1)	t½(h)	t½(d)
70	0.5728	1.2	0.1
60	0.1840	3.8	0.2
50	0.0651	10.7	0.4
25	0.0028	249.4	10.4

 

Applicant's summary and conclusion

Conclusions:

The half-life periods at 25 °C of Reaktiv-Gelb F-66923 FW are:
> 1 year at pH 4 (preliminary test)
10.4 d at pH 7 (extrapolated from the results of test 1 and 3)
< 1 d at pH 9 (derived from hydrolysis investigations with substances of the same class)

Executive summary:

The objective of this study was the determination of the abiotic degradation of the test substance (the main compound), i.e. the determination of the hydrolysis rate as a function of the pH-value according to 84/449/EWG. Study conducted in compliance with GLP.

 

The decomposition at pH 4 is less than 10% after 5 days, thus making further tests unnecessary. The test substance may be considered hydrolytically stable at pH 4 according to the guideline. Therefore the half-life period, at 25°C, may be estimated as greater than one year. The preliminary testsat pH 7 indicate that an examination of the linearity of the hydrolysis kinetics

 

The half-life periods at 25 °Cof Reaktiv-Gelb F-66923 FW are:

>1year at pH4 (preliminary test)

10.4d at pH7 (extrapolated from the results of test 1 and 3)

<1d at pH9 (derived from hydrolysis investigations with substances of the same class)