Tetrasodium 4-amino-5-hydroxy-6-[[2-methoxy-5-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]azo]-3-[[4-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]azo]naphthalene-2,7-disulphonate

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Type of information:

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

Adequacy of study:

key study

Study period:

1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

see read across justification in section 13

Reason / purpose for cross-reference:

read-across source

Duration:

19 d

pH:

4

Temp.:

60

Initial conc. measured:

209.8 mg/L

Duration:

168 h

pH:

4

Temp.:

70

Initial conc. measured:

211 mg/L

Duration:

71 h

pH:

4

Temp.:

80

Initial conc. measured:

230 mg/L

Duration:

52 h

pH:

7

Temp.:

25

Initial conc. measured:

221 mg/L

Duration:

60 min

pH:

9

Temp.:

20

Initial conc. measured:

226 mg/L

Preliminary study:

at 50°C after 2.4h the following results were observed: pH4: 1.7% degradation
pH7: 98.9% degradation
pH9: >99% degradation
at 50°C and pH 4 after 5 d a degradation of 10% was obserfed

Transformation products:

yes

No.:

#1

No.:

#2

No.:

#2

No.:

#3

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

#1: retention time in HPLC: 11.2 minutes: after 2.4 h 75% at 50°C and pH7 (Reactive Black 5 bis-vinyl)
#2: retention time in HPLC of both isomers: 8.6 min;
#3: retention time in HPLC: 8.2 min

% Recovery:

33.5

pH:

4

Temp.:

80 °C

Duration:

71.5 h

% Recovery:

42.3

pH:

4

Temp.:

70 °C

Duration:

168 h

% Recovery:

48

pH:

4

Temp.:

60 °C

Duration:

18.98 d

% Recovery:

41.7

pH:

7

Temp.:

25 °C

Duration:

51.9 h

% Recovery:

45.3

pH:

9

Temp.:

20 °C

Duration:

60 min

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

<= 0 d-1

DT50:

258.5 wk

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

<= 0.015 h-1

DT50:

1.9 d

pH:

9

Temp.:

20 °C

Hydrolysis rate constant:

<= 0.015 min-1

DT50:

48 min

Validity criteria fulfilled:

yes

Conclusions:

At environmental conditions, the test substance is hydrolytically unstable at pH 7 and 9 and hydrlotically stable at pH 4

Executive summary:

The structural analogue was tested for abiotic degradation according to OECD 111. In addition to pH 4, 7, 9 as required by the guideline, the substance was also tested at pH 11 (dyeing conditions) and pH 1.2.

At pH 1.2 and 37°C, there was no abiotic degradation within the 5 days observation period. At pH 4, 7, 9, and 11, the test substance was not stable at 50°C. The degration at pH 4, 7, and 9 where hence investiated further.

At pH 4, the half-life at 25°C is ca. 5 years; at pH 7, the half-life at 25°C is ca. 2 days; at pH 9, the half-life at 20°C is ca. 50 minutes.

 

pH	T [°C]	k=<	t1/2
4	25	0.0004 1/d	258.5 weeks
7	25	0.0152 1/d	1.9 days
9	20	0.0146 1/min	48 minutes

 

During degradation of the bis-ester, both isoforms of the mono-vinyl form appear temporarily as degradation product. One main degradation product is the bis-vinyl as the active dye-form which further hydrolyses to the hydroxy form (-OH).

Reference 2

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1989

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)

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Sample storage conditions before analysis: inert gas atmosphere; at the dark; the period from dissolution up to the testing at thermostated temeprature was kept as short as possible

Buffers:

- pH: 4, 7, 9
- Type and final molarity of buffer:
- Composition of buffer:
pH4: potassium hydrogene phthtalate in water; adjustment of the pH by sodium hydroxide
pH7: monopotassium dihydrogene phosphate in water; adjustment of the pH by sodium hydroxide
pH9: boric acid in aqueous potassium chloride solution; adjustment of the pH with sodium hydroxide

Estimation method (if used):

not applicable

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used:
- Sterilisation method:
- Lighting:
- Measures taken to avoid photolytic effects:
- Measures to exclude oxygen:
- Details on test procedure for unstable compounds:
- Details of traps for volatile, if any
- If no traps were used, is the test system closed/open
- Is there any indication of the test material adsorbing to the walls of the test apparatus?
TEST MEDIUM
- Volume used/treatment
- Kind and purity of water:
- Preparation of test medium:
- Renewal of test solution:
- Identity and concentration of co-solvent:
OTHER TEST CONDITIONS
- Adjustment of pH:
- Dissolved oxygen:

Duration:

19 d

pH:

4

Temp.:

60

Initial conc. measured:

209.8 mg/L

Duration:

168 h

pH:

4

Temp.:

70

Initial conc. measured:

211 mg/L

Duration:

71 h

pH:

4

Temp.:

80

Initial conc. measured:

230 mg/L

Duration:

52 h

pH:

7

Temp.:

25

Initial conc. measured:

221 mg/L

Duration:

60 min

pH:

9

Temp.:

20

Initial conc. measured:

226 mg/L

Positive controls:

no

Negative controls:

no

Preliminary study:

at 50°C after 2.4h the following results were observed: pH4: 1.7% degradation
pH7: 98.9% degradation
pH9: >99% degradation
at 50°C and pH 4 after 5 d a degradation of 10% was obserfed

Transformation products:

yes

No.:

#1

No.:

#2

No.:

#2

No.:

#3

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

#1: retention time in HPLC: 11.2 minutes: after 2.4 h 75% at 50°C and pH7 (Reactive Black 5 bis-vinyl)
#2: retention time in HPLC of both isomers: 8.6 min;
#3: retention time in HPLC: 8.2 min

% Recovery:

33.5

pH:

4

Temp.:

80 °C

Duration:

71.5 h

% Recovery:

42.3

pH:

4

Temp.:

70 °C

Duration:

168 h

% Recovery:

48

pH:

4

Temp.:

60 °C

Duration:

18.98 d

% Recovery:

41.7

pH:

7

Temp.:

25 °C

Duration:

51.9 h

% Recovery:

45.3

pH:

9

Temp.:

20 °C

Duration:

60 min

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

<= 0 d-1

DT50:

258.5 wk

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

<= 0.015 h-1

DT50:

1.9 d

pH:

9

Temp.:

20 °C

Hydrolysis rate constant:

<= 0.015 min-1

DT50:

48 min

Validity criteria fulfilled:

yes

Conclusions:

At environmental conditions, the test substance is hydrolytically unstable at pH 7 and 9 and hydrlotically stable at pH 4

Executive summary:

The structural analogue, Reactive Black 5, was tested for abiotic degradation according to OECD 111. In addition to pH 4, 7, 9 as required by the guideline, the substance was also tested at pH 11 (dyeing conditions) and pH 1.2.

At pH 1.2 and 37°C, there was no abiotic degradation within the 5 days observation period. At pH 4, 7, 9, and 11, the test substance was not stable at 50°C. The degration at pH 4, 7, and 9 where hence investiated further.

At pH 4, the half-life at 25°C is ca. 5 years; at pH 7, the half-life at 25°C is ca. 2 days; at pH 9, the half-life at 20°C is ca. 50 minutes.

pH	T [°C]	k=<	t1/2
4	25	0.0004 1/d	258.5 weeks
7	25	0.0152 1/d	1.9 days
9	20	0.0146 1/min	48 minutes

 

During degradation of the bis-ester, both isoforms of the mono-vinyl form appear temporarily as degradation product. One main degradation product is Reactive Black 5 bis-vinyl as the active dye-form which further hydrolyses to Reactive Black 5-OH.

Description of key information

Substance is not hydrolytically stable at pH 7, 9, and 11 at environmental or use-conditions

Key value for chemical safety assessment

Half-life for hydrolysis:

2 d

at the temperature of:

25 °C

Additional information

The structural analogue, Reactive Black 5, was tested for abiotic degradation according to OECD 111. In addition to pH 4, 7, 9 as required by the guideline, the substance was also tested at pH 11 (dyeing conditions) and pH 1.2.

At pH 1.2 and 37°C, there was no abiotic degradation within the 5 days observation period. At pH 4, 7, 9, and 11, the test substance was not stable at 50°C. The degradation at pH 4, 7, and 9 were hence investigated further.

At pH 4, the half-life at 25°C is ca. 5 years; at pH 7, the half-life at 25°C is ca. 2 days; at pH 9, the half-life at 20°C is ca. 50 minutes.

During degradation of the bis-ester, both isoforms of the mono-vinyl form appear temporarily as degradation product. One main degradation product is Reactive Black 5 bis-vinyl as the active dye-form which further hydrolyses to Reactive Black 5-OH.