JAUNE REACTIF 181

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 November 1990 to 18 January 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

other: EEC Guideline L 251/C.10 (1984) based on OECD guideline 111

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Product designation: Monoazo Yellow BG 3247
Identification: FAT 40'400/A BG 3247/TV 6

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

SAMPLING:
For each solution of different pH and temperature, i.e. solutions of pH=4 and temp. of 50, 60 and 70 °C, solutions of pH=7 and 9 and temp. of 50°C two runs are performed and aliquots after 24 and 120 hrs were taken for the preliminary test and througout the test for the main test.

Buffers:

- pH 4: 0.1 mole acetic acid + 0.1 mole sodium acetat diluted to 1000 mL with water + 60 mL 1N HCl.
- pH 7: 0.041 mole di-sodium-hydrogen phosphate+ 0.028 mole potassium di-hydrogen phosphate diluted to 1000 mL with water.
- pH 9: 0.043 mole di-sodium tetraborate + 0.017 mole potassium di-hydrogen phosphate diluted to 1000 mL with water.

Estimation method (if used):

Linear regression and Arrhenius equation.

Details on test conditions:

Three test solutions are prepared as follows: 0.05000 to 0.06000 g test substance is accurately weighed, dissolved in and diluted to 250.0 mL with water. 10.00 mL of this solution are diluted to 100.0 mL with the buffer solutions pH 4.0, pH 7.0, pH 9.0 respectively. Only brown volumetric flasks are used. The flasks are previously rinsed with nitrogen for 5 minutes. After the hydrolysis period: a) 10.00 mL of the test solution at pH 4 are diluted with 1.37 mL 1 N NaOH and 2.00 ml of pH 7 buffer solution. b) The test solution at pH 7 is ready for measurement. c) 10.00 ml of the test solution at pH 9 are diluted with 0.65 mL 1 N HCl and 2.00 mL of pH 7 buffer solution. Thus producing three solutions ready for measurement. If the solutions are not immediately measured put the flask in a refrigerator.

REAGENTS AND SOLVENTS
- Kind of water: Distilled water.
- Acetonitrile
- tetrabutylammoniumbromide, puriss = TBAB
- 1 N NaOH
- 1 N HCl

Duration:

2.4 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

0.023 g/L

Duration:

120 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

0.023 g/L

Duration:

456 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

0.022 g/L

Duration:

193 h

pH:

4

Temp.:

60 °C

Initial conc. measured:

0.023 g/L

Duration:

80 h

pH:

4

Temp.:

70 °C

Initial conc. measured:

0.023 g/L

Duration:

2.4 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

0.023 g/L

Duration:

120 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

0.023 g/L

Duration:

2.4 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

0.023 g/L

Duration:

120 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

0.023 g/L

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Preliminary study:

Preliminary tests of solutions of pH 4, 7 and 9 at the temperature of 50 °C showed that the test substance is stable at pH 7 and 9 at 50 °C with calculated half-life periods of >1 year at these pH values. At 50 °C and pH 4, the test substance was hydrolized more than 10 %. Hence, hydrolysis at this pH was further examined at 60 and 70 °C.

Transformation products:

no

% Recovery:

38

pH:

4

Temp.:

50 °C

Duration:

456 h

% Recovery:

38

pH:

4

Temp.:

60 °C

Duration:

193 h

% Recovery:

38.15

pH:

4

Temp.:

70 °C

Duration:

80 h

pH:

4

Temp.:

50 °C

Hydrolysis rate constant:

0 s-1

DT50:

327.6 h

Type:

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

Remarks on result:

other: Regression equation, r^2=0.9977

pH:

4

Temp.:

60 °C

Hydrolysis rate constant:

0 s-1

DT50:

136.2 h

Type:

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

Remarks on result:

other: Regression equation, r^2=0.99985

pH:

4

Temp.:

70 °C

Hydrolysis rate constant:

0 s-1

DT50:

58.6 h

Type:

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

Remarks on result:

other: Regression equation, r^2=0.9991

Other kinetic parameters:

none

Details on results:

The hydrolysis rate at pH 4 and temperature 25 °C has been calculated: k = 0.00000004924 s^(-1) and half life period: t1/2=3909.6 hours.

At 50, 60 and 70 °C and pH 4, at 25 °C the test substance is calculated to have a half-life of 3910 hours (i.e. < ½ year). From the preliminary test, calculated half-life periods at 25 °C at pH 7 and 9 at 25 °C are >1 year.

Validity criteria fulfilled:

yes

Conclusions:

The test substance is hydrolitically stable at pH 7 and 9. At pH 4 the half-life time at 25 °C is calculated to be 3910 hrs.

Executive summary:

In a GLP-compliant hydrolysis study according to EEC guideline L 251/C.1 0.(1 984) based on OECD guideline 111, hydrolysis of the test substance was tested at varying temperatures and as a function of pH. In a preliminary test hydrolysis was measured at 50 °C at pH 4, 7 and 9. In the main test half lifes were determined at 50, 60 and 70 °C at pH 4. Residual test substance was determined by HPLC. In the preliminary test at 50 °C and pH 4, 7, and 9, degradations were 1.2 %, -1.3 % and 1.3 % after 2.4 hours and 24.0 %, -0.1 %, and 4.8 % after 120 hours, respectively. From the main study the following half-lifes were obtained: pH 4; 327.6, 136.2 and 58.6 and 50 °C, 60 °C and 70 °C, respectively. From these results, the half-life at 25 °C was calculated to be 3910 hours at pH 4 and more than a year at pH 7, and 9. It can be concluded that the test substance is hydrolitically stable at pH 7 and 9.

Description of key information

The test substance is hydrolytically stable at pH 7 and 9. At pH 4 the half-life time at 25 °C is calculated to be 3910 hrs.

Key value for chemical safety assessment

Half-life for hydrolysis:

3 910 h

at the temperature of:

25 °C

Additional information

In a GLP-compliant study according to EEC guideline L 251/C.1 0.(1 984) based on OECD guideline 111, hydrolysis of the test substance was tested at varying temperatures and as a function of pH (CG, 1991). Based on the results obtained at the various experimental temperatures at a set pH (pH 4, 6 and 9), half-life periods of the test substance at 25 °C were calculated by means of the Arrhenius equation. In a preliminary test it was determined that the test substance is stable towards hydrolysis at 50 °C at pH 7 and pH9 (percentage hydrolysis of <10 % after 5 days incubation). Half-life times at these pH values and 25 °C were calculated to be >1 year. At pH4 and 50 °C the percentage hydrolysis was found to be >10 % after 5 days incubation. Therefore, at this pH additional testing was performed at 60 and 70 °C. Based on the finding at 50, 60 and 70 °C, the half-life time of the test substance at pH 4 and 25 °C was calculated to be 3909.6 hours (~0.45 year). In a GLP-compliant study according to OECD guideline 111, hydrolysis of the test substance was tested at varying temperatures and as a function of pH (CG, 1991). Based on the results obtained at the various experimental temperatures at a set pH (pH 4, 6 and 9), half-life periods of the test substance at 25 °C were calculated by means of the Arrhenius equation. In a preliminary test it was determined that the test substance is stable towards hydrolysis at 50 °C at pH 7 and pH9 (percentage hydrolysis of <10 % after 5 days incubation). Half-life times at these pH values and 25 °C were calculated to be >1 year. At pH4 and 50 °C the percentage hydrolysis was found to be >10 % after 5 days incubation. Therefore, at this pH additional testing was performed at 60 and 70 °C. Based on the finding at 50, 60 and 70 °C, the half-life time of the test substance at pH 4 and 25 °C was calculated to be 3909.6 hours (~0.45 year). It can be concluded that the test substance is hydrolytically stable at pH 7 and 9.