Tetrasodium 2-[[4-[[4-[[1-hydroxy-6-(phenylamino)-3-sulphonato-2-naphthyl]azo]-1-naphthyl]azo]-6-sulphonato-1-naphthyl]azo]benzene-1,4-disulphonate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15.08.2016-24.08.2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Buffers:

The hydrolysis of test substance was examined at buffered solutions of selected pH value: 4, 7 and 9. The actual pH value at given temperature was measured using a calibrated pH meter. All prepared buffer solutions were sterilized in a pressure cooker for 50 min and purged by nitrogen. -Buffer pH 4.0-pH 4.04, (24.1°C)-Buffer pH 7.0-pH 6.94 (24.1°C)-Buffer pH 9.0-pH 8.92 (24.1°C)Preparation of mobile phases:A: Approximately 0.39 g of CH3COONH4 was dissolved in 1L of deionized H2O. B: 50 mL of deionized H2O and 950 mL of MeOH were mixed.

Details on test conditions:

TTEST SYSTEM- Type, material and volume of test flasks, other equipment used: volumetric flask wrapped with an aluminum foil and tightly closed with a stopper.- Sterilisation method: All glassware, reagent-grade water and buffer solutions were sterilized in an autoclave (121 °C, 50 min).TEST MEDIUM- Kind and purity of water: deonized waterCALIBRATION SOLUTIONSStock Solution (SS, 10 000 mg/L): ): Approximately 50 mg of Direct Blue 78 was weighed into a 50 mL volumetric flask, dissolved in and diluted to volume with deionized H2O.SAMPLE SOLUTIONS4.19 mL of (1000 mg/L) standard solution were pipetted into a 50mL volumetric flask and diluted with a buffered solution of certain pH (4, 7, or 9) – in duplicate. A nominal concentration of 80 mg/L Direct Blue 78 was prepared. Each buffered sample solution was bubbled with nitrogen for at least 5 min. The sample solutions in volumetric flasks were wrapped with an aluminum foil and tightly closed with a stopper. During the experimental part of hydrolysis, the volumetric flasks were placed in the thermostatic bath kept at a given temperature. At certain period of time, a portion of sample solution was transferred into a vial followed by a quick cooling to room temperature.

Duration:

5.05 d

pH:

3.95

Temp.:

50 °C

Duration:

5.05 d

pH:

6.97

Temp.:

50 °C

Duration:

5.05 d

pH:

8.95

Temp.:

50 °C

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Preliminary study:

The preliminary test was performed at 50 °C over the period of 5 days. All glassware, reagent-grade water and buffer solutions were sterilized in a pressure cooker for 50 min. The actual pH value of each buffered solution is given in Table 2. There was no observation of degradation greater than 10 % in all buffered solutions over period of 5 days. Test substance was considered to be stable at all tested pH values (Table 3).

Transformation products:

no

% Recovery:

-1.3

pH:

3.95

Temp.:

50 °C

Duration:

5.05 d

Remarks on result:

hydrolytically stable based on preliminary test

% Recovery:

-4.7

pH:

6.97

Temp.:

50 °C

Duration:

5.05 d

Remarks on result:

hydrolytically stable based on preliminary test

% Recovery:

-4.8

pH:

8.92

Temp.:

50 °C

Duration:

5.05 d

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

3.95

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

6.97

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

8.92

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Table2:pH values of buffersolutions

pH at room temperature	pH at 50 °C
4.04	3.95
6.94	6.97
8.92	8.95

Table3:Results of preliminary test

pH 3.95 at 50 °C		pH 6.97 at 50 °C		pH 8.95 at 50 °C
Days	Hydrolysis (%)	Days	Hydrolysis (%)	Days	Hydrolysis (%)
0.00	0.0	0.00	0.0	0.00	0.0
3.11	-0.6	3.11	-1.7	3.11	-1.7
4.19	-1.0	4.19	-2.9	4.19	-2.7
5.05	-1.3	5.05	-4.7	5.05	-4.8

Validity criteria fulfilled:

yes

Conclusions:

The preliminary test has shown that the test substance was not hydrolyzed by more than 10% in period of 5 days at pH 4, 7 and 9. Therefore the test substance was considered to be hydrolytically stable at above pHs. It can be assumed that the half-time at 25 °C would be > 1 year.

Executive summary:

The procedure was performed according to: Method C.7 – Degradation – Abiotic Degradation: Hydrolysis as a Function of pH, Council regulation (EC) No 440/2008. Published in OJ No L 142/518 May 2008 and OECD Test Guidline No.111, Hydrolysis as a function of pH, Adopted April 13, 2004.

 

The preliminary test has shown that the test substance was not hydrolyzed by more than 10% in period of 5 days at pH 4, 7 and 9. Therefore the test substance was considered to be hydrolytically stable at above pHs. It can be assumed that the half-time at 25 °C would be > 1 year.

Description of key information

Test was performed according to the Method C.7 – Degradation – Abiotic Degradation: Hydrolysis as a Function of pH, Council regulation (EC) No 440/2008. Published in OJ No L 142/518 May 2008 and OECD Test Guidline No.111, Hydrolysis as a function of pH, Adopted April 13, 2004.

Only one study is available.

GLP study.

Klimish score 1.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C