Reaction products of 4-amino-5-hydroxynaphthalene-2,7-disulfonic acid, coupled twice with diazotized 2-[(4-aminophenyl)sulfonyl]ethyl hydrogen sulfate, sodium salts

Hydrolysis

Link to relevant study record(s)

Reference

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

Specific details on test material used for the study:

see test material information

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Sample storage conditions before analysis: inert gas atmosphere; in the dark; the period from dissolution up to the testing at thermostated temperature 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:

after 2.4 h at 50 °C the following results were observed: pH 4: 1.7 % degradation
pH 7: 98.9 % degradation
pH 9: >99 % degradation
after 5 days at 50 °C and pH 4 a degradation of 10 % was observed

Transformation products:

yes

No.:

#1

No.:

#2

No.:

#3

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

#1: retention time in HPLC: 11.4 minutes: after 2.4 h 75 % at 50 °C and pH 7
#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:

0.02 d-1

DT50:

> 1 - < 2 d

pH:

9

Temp.:

20 °C

Hydrolysis rate constant:

0.01 min-1

DT50:

48 min

Validity criteria fulfilled:

yes

Conclusions:

not hydrolytically stable at pH 7 and 9; hydrolytically stable at pH 4;

Executive summary:

In a GLP compliant guideline study the test substance is found not to be hydrolytically stable at pH 7 and 9 but hydrolytically stable at pH 4.

Overall results:

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

 

Description of key information

In a GLP-compliant guideline study the test substance was found to be not hydrolytically stable at pH 7 and pH 9, but stable at pH 4.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 d

at the temperature of:

25 °C