A mixture of: disodium 6-[3-carboxy-4,5-dihydro-5-oxo-4-sulfonatophenyl)pyrazolin-4-yl-azo]-3-[2-oxido-4-(ethensulfonyl)-5-methoxyphenylazo]-4-oxidonaphthalene-2-sulfonate copper (II) complex; disodium 6-[3-carboxy-4,5-dihydro-5-oxo-4-sulfonatophenyl)pyrazolin-4-yl-azo]-3-[2-oxido-4-(2-hydroxyethylsulfonyl)-5-methoxyphenylazo]-4-oxidonaphthalene-2-sulfonate copper (II) complex

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

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

Reference substance name:

A mixture of: disodium 6-[3-carboxy-4,5-dihydro-5-oxo-4-sulfonatophenyl)pyrazolin-4-yl-azo]-3-[2-oxido-4-(ethensulfonyl)-5-methoxyphenylazo]-4-oxidonaphthalene-2-sulfonate copper (II) complex; disodium 6-[3-carboxy-4,5-dihydro-5-oxo-4-sulfonatophenyl)pyrazolin-4-yl-azo]-3-[2-oxido-4-(2-hydroxyethylsulfonyl)-5-methoxyphenylazo]-4-oxidonaphthalene-2-sulfonate copper (II) complex;

EC Number:

423-940-7

EC Name:

A mixture of: disodium 6-[3-carboxy-4,5-dihydro-5-oxo-4-sulfonatophenyl)pyrazolin-4-yl-azo]-3-[2-oxido-4-(ethensulfonyl)-5-methoxyphenylazo]-4-oxidonaphthalene-2-sulfonate copper (II) complex; disodium 6-[3-carboxy-4,5-dihydro-5-oxo-4-sulfonatophenyl)pyrazolin-4-yl-azo]-3-[2-oxido-4-(2-hydroxyethylsulfonyl)-5-methoxyphenylazo]-4-oxidonaphthalene-2-sulfonate copper (II) complex;

Cas Number:

85585-91-7

IUPAC Name:

4-[2-(7-{2-[4-(ethenesulfonyl)-2-hydroxy-5-methoxyphenyl]diazen-1-yl}-8-hydroxy-6-sulfonaphthalen-2-yl)diazen-1-yl]-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acid 4-[2-(8-hydroxy-7-{2-[2-hydroxy-4-(2-hydroxyethanesulfonyl)-5-methoxyphenyl]diazen-1-yl}-6-sulfonaphthalen-2-yl)diazen-1-yl]-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acid dicopper tetrasodium hydride

Test material form:

solid

Specific details on test material used for the study:

Identification: Pacified Reactive Black 31
Description: Dark blue crystals
Batch: 9T-55
Purity: 89%
Storage: At room temperature in the dark
Stability under storage conditions: Stable

Radiolabelling:

no

Study design

Analytical monitoring:

yes

Details on sampling:

Test 1
Suring the preliminary tests, significant hydrolysis was observed at pH 9. For pH 4 and 7, no conclusions for the rate of hydrolysis could be made. Therefore, Test 1 was carried out at all the pH values in duplicate.

After preparation, the test solutions pH 4, 7 and 9 were placed in a thermostatically controlled waterbbath at 70°C (for pH 4 and 7) and at 60°C for pH 9 in the dark.

The concentration of the test substance at pH 4 was determined immediately after preparation (T=0) and 39.5 and 163 hours after T=0.

The concentration of the test substance at pH 7 was determined immediately after preparation (T=0) and 39.5, 63.0, 70.0, 90.5, 163, 187, 211, 236 and 260 hours after T=0.

The concentration of the test substance at pH 9 was determined immediately after preparation (T=0) and 24.0, 28.0, 34.0, 51.0 and 72.5 hours after T=0.

In addition, the lines from Test 1 for pH's 4, 7 and 9 were also used for the estimation of K 50°C (for pH 4) and K 25°C (for pH's 7 and 9). Therefore, the logarithms of all reactive concentrations were plotted against time for these pH values.


Test 3
Because the resultant line from Test 1 was a straight line for pH's 4, 7 and9, Test 3 was carried out.

Because Test 1 at pH 4 and pH 7 was performed at 70°C, Test 3 was performed at only one temperature >50°C; i.e. 80°C. Because Test 1 at pH 9 was conducted at 60°C, Test 3 was performed at only one temperature >50°C; i.e. 70°C.

After preparation, each test solution was placed in a thermostatically controlled waterbath at the specified temperature, and in the dark.

For pH 4, the concentration of the test substance was determined immediately after preparation (T=0) and 16.0, 39.5, 63.0, 70.0 and 163 hours after T=0.

For pH 7, the concentration of the test substance was determined immediately after preparation (T=0) and 16.0, 39.5, 43.5, 51.5, 63.0, 70.0, 90.0 and 163 hours after T=0.

For pH 9, the concentration of the test substance was determined immediately after preparation (T=0) and 13.3, 24.0 and 28.0 hours after T=0.

The logarithms of all relative concentrations wre plotted against time for these pH values.

Details on test conditions:

Preparation of the test solutions
Prior to the performance of each test, the test solutions were freshly prepared. Therefore, an accurately weighed amount of approximately 276 - 316 mg test substance was added to 50.0 ml buffer solution at pH 4, pH 7 or pH 9. The resultant solutions were filter sterilized through a 0.2 µm membrane filter and transferred into sterilised glass vessels.

To exclude oxygen, nitrogen gas was bubbled through each solution for approximately 5 minutes. Thereafter, each vessel was tightly sealed with a septum-crimcap.

Preliminary test
After preparation, the test solutions at pH 4, 7 and 9 were placed in a thermostatically controlled waterbath at 50°C in the dark. The concentration of the test substance was determined immediately after preparation (T=0), after 2.4 hours and after 5 days.

The repeatability of the chromatograhoic method might have been insufficient to be able to determine changes in the test substance concentration of a few percent relative, to nominal. Therefore, it could not be assured that the decrease in concentration at pH 4 and 7 after 120 hours was really >10%. for this reason, the preliminary test for pH 4 and pH 7 was performed a second time.

Duration of test

Duration of test 1

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

>= 3.98 - <= 5.2 g/L

Remarks:

Preliminary test

Duration of test 2

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

ca. 6.23 - <= 6.78 g/L

Remarks:

Preliminary test

Duration of test 3

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

6.86 g/L

Remarks:

Preliminary test

Duration of test 4

Duration:

163 h

pH:

4

Temp.:

70 °C

Initial conc. measured:

>= 5.08 - <= 6.1 g/L

Remarks:

Test 1

Duration of test 5

Duration:

260 h

pH:

7

Temp.:

70 °C

Initial conc. measured:

>= 5.77 - <= 6.12 g/L

Remarks:

Test 1

Duration of test 6

Duration:

72.5 h

pH:

9

Temp.:

60 °C

Initial conc. measured:

>= 5.52 - <= 5.97 g/L

Remarks:

Test 1

Duration of test 7

Duration:

163 h

pH:

4

Temp.:

80 °C

Initial conc. measured:

6.33 g/L

Remarks:

Test 3

Duration of test 8

Duration:

163 h

pH:

7

Temp.:

80 °C

Initial conc. measured:

5.75 g/L

Remarks:

Test 3

Duration of test 9

Duration:

28 h

pH:

9

Temp.:

70 °C

Initial conc. measured:

>= 5.87 - <= 6.21 g/L

Remarks:

Test 3

Number of replicates:

Upto three

Positive controls:

no

Negative controls:

no

Results and discussion

Preliminary study:

For pH 4 and pH 7, no conclusions for the rate of hydrolysis could be made. At pH 9, a decrease in concentration <50% after 2.4 hours and a decrease in concentration >10% after 5 days was observed,

Therefore, Test 1 had to be performed at pH 4, 7 and 9.

Transformation products:

no

Dissipation DT50 of parent compound

Dissipation DT50 of parent compound 1

Key result

pH:

7

Temp.:

25 °C

DT50:

120 000 h

Type:

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

Dissipation DT50 of parent compound 2

Key result

pH:

9

Temp.:

25 °C

DT50:

10 000 h

Type:

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

Details on results:

The half-life times were 3.3E+02 hours at 70°C, 1.1E+02 hours at 80°C at pH7 and 58 hours (60°C), 16 hours (70°C) at pH 9.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Pacified Reactive Black 31 is hydrolytically stable at pH 4, and hydrolytically unsable at pH 7 and 9, under the conditions of the test.

Executive summary:

The determination of the hydrolysis as a function of pH was based on the EEC-Directive 92/69 EEC, Part C, Metjods for the determination of Ecotoxicity, C.7: "Abiotic degradation: Hydrolysis as a function of pH".

Pacified Reactive Black was determined to be hydrolytically stable at pH4, and hydrolytically unstable at pH 7 and 9, under the conditions of the test.

The half-life times were 3.3E+02 hours at 70°C, 1.1E+02 hours at 80°C at pH7 and 58 hours (60°C), 16 hours (70°C) at pH 9.

From these values the half-life times at 25°C were estimated: 1.2E+05 hours at pH 7 and 1.0E+04 hours at pH 9.