Trisodium 2,4-diamino-3,5-bis-[4-(2-sulfonatoethoxy)sulfonyl)phenylazo]benzenesulfonate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Nov. 08, 1996 to Feb. 20, 1997

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:

other: EC Guideline C.7 (Official Journal of the European Communities L 383 A), 1992

GLP compliance:

yes (incl. QA statement)

Remarks:

Swiss GLP

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: WP 2/96
- Expiration date of the lot/batch: November, 2004

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: The test substance can be stored at room temperature

Radiolabelling:

not specified

Analytical monitoring:

yes

Buffers:

pH 4.0: Ciba-Geigy Code No. P07: 0.1 mole acetic add + 0.1 mole sodium acetate diluted to 1000 ml with water + 60.0 ml 1.0 N HCI.
pH 7.0: Ciba-Geigy Code No, P10: 0.041 mole disodium hydrogen phosphate + 0.028 mole potassium dihydrogen phosphate diluted to 1000 ml with water,
pH 9.0: Ciba-Geigy Code No, P12: 0,043 mole disodium tetraborate + 0.017 mole potassium dihydrogen phosphate diluted to 1000 ml with water.

Details on test conditions:

300.0 to 330.0 mg test substance were dissolved and diluted to 100.0 ml with water. 10.0 ml of this solution were pipetted into a 100 ml measuring flask, which was then filled up to the mark with the respective buffer solution.
Calibration solutions: Three different calibration solutions were prepared (immediately before use), which had approximately the same concentrations of acid and alkali, respectively, and buffer as the corresponding test solutions.

Duration:

59.6 h

pH:

4

Temp.:

80 °C

Duration:

113.4 h

pH:

7

Temp.:

25 °C

Duration:

160.2 h

pH:

4

Temp.:

70 °C

Duration:

41.1 h

pH:

4

Temp.:

80 °C

Number of replicates:

2 replicates

Positive controls:

not specified

Negative controls:

not specified

Statistical methods:

no data

Preliminary study:

This test was performed with the test solutions at pH 4, 7 and 9 at 50 °C for 2.4 hours and 5 days respectively.
The results of this test permit an estimate as to whether the half-life period (t1/2) less than 2.4 h (case I) or lower than 10 % of hydrolysis after 5 days (case II). The corresponding estimates for conditions more representative of the environment (25 °C) are: case I: t1/2 < 1 day; case II: t1/2 > 1 year.
For all cases between those mentioned above, test 1 must be carried out for the individual pH- levels.
Result: The test substance is unstable at pH 9 at 50 °C; it has a half-life period shorter than one day at 25 °C and pH 9.
Test 1 must be carried out at pH 4 and pH 7.

Test performance:

The test substance is dissolved in aqueous buffer solution, the temperature and the pH are checked at pH 4, 7 and 9 respectively.
The decrease of the concentration with time is determined by HPLC, In case of hydrolysis, the logarithms of the concentration are plotted as a function of time, and if the result is a straight line, the reaction is considered to be of (pseudo-) first order. The rate constant and the half-life period are calculated using the slope of the line. When it is not practical to determine a rate constant directly at 25 °C, the half-life period can usually be estimated using the Arrhenius equation.

Transformation products:

not specified

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

0.002 s-1

DT50:

12 233.9 h

Type:

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

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

0.227 s-1

DT50:

84.8 h

Type:

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

pH:

9

Temp.:

25 °C

DT50:

< 1 d

Remarks on result:

other:

Remarks:

Results of preliminary test

Other kinetic parameters:

no data

Validity criteria fulfilled:

yes

Conclusions:

Half-life period of FAT 45176/A at pH 4 and pH 7 were 12233.9 h (about 1.4 years) and 84.8 h (about 3.5 days) at 25 °C respectively.

Executive summary:

Hydrolysis as a function of pH was performed with FAT 45176/A under GLP compliance according to OECD 111and EU C.7 guideline. Based on the study results, test substance at pH 4 has a half-life period of 12233.9 h (about 1.4 years) at 25 °C, at pH 7 has a half-life period of 84.8 h (about 3.5 days) at 25 °C, and is unstable at pH 9 with a half-life period of shorter than one day at 25 °C.

Description of key information

Half-life period of Reactive Orange 136 at pH 4 and pH 7 were 12233.9 h (about 1.4 years) and 84.8 h (about 3.5 days) at 25 °C respectively.

Key value for chemical safety assessment

Half-life for hydrolysis:

3.5 d

at the temperature of:

25 °C

Additional information

Hydrolysis as a function of pH was performed with FAT 45176/A under GLP compliance according to OECD 111and EU C.7 guideline. Based on the study results, test substance at pH 4 has a half-life period of 12233.9 h (about 1.4 years) at 25 °C, at pH 7 has a half-life period of 84.8 h (about 3.5 days) at 25 °C, and is unstable at pH 9 with a half-life period of shorter than one day at 25 °C.