Disodium 6-hydroxy-5-[[4-[[4-(phenylamino)-3-sulphonatophenyl]azo]naphthyl]azo]naphthalene-2-sulphonate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09.08.2016 - 15.08.2016

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)

Version / remarks:

Council regulation (EC) No 440/2008. Published in OJ No L 142/518 May 2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Version / remarks:

Adopted April 13, 2004

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: 4.0, 7.0 and 9.0. The actual pH value at given temperature was measured using a calibrated pH meter. All prepared buffer solutions were sterilized in an autoclave (121°C, 50 min) and purged by nitrogen. Buffer pH 4: 500mL 0.1 M potassium hydrogen phthalate + 4.0 mL 0.1 M NaOH / 1000 mL UPWpH 4.03 at 25.4°CBuffer pH 7: 296 mL 0.1M NaOH + 500 mL 0.1 M potassium dihydrogen phosphate/ 1000 mL UPWpH 7.02 at 25.4°C Buffer pH 9: 213 mL 0.1 M NaOH + 500 mL 0.1 M KCl in 0,1 M H3BO3 / 1000 mL UPW.pH 8.96 at 25.4°C

Details on test conditions:

TEST SYSTEM - Type, material and volume of test flasks, other equipment used: volumetric flask, the body of each flask was wrapped in an aluminium foil and tightly closed - Sterilisation method: all glassware, reagent-grade water and buffer solutions were sterilised by autoclave (121°C, 50 min) - Measures to exclude oxygen: oxygen is removed from a solution by purging with nitrogen TEST MEDIUM - Kind and purity of water: Ultrapure Water (UPW) – prepared in house by water purification system; Water purification system IWA 20iol, Watek CALIBRATION SOLUTIONApproximately 1.6 g of Acid Black 26 was weighed into a 100 mL volumetric flask, 1mL of methanol was added and then dissolved with UPW in an ultrasonic bath for 5 minutes and diluted to volume (stock solution - SS). This stock solution was diluted to four more concentrations (calibration solutions - CS) in this manner:CS No.1: 0.3 mL SS/100mL, nominal concentration of AB26 - 50 mg/LCS No.2: 0.4 mL SS/100mL, nominal concentration of AB26 - 64 mg/LCS No.3: 0.5 mL SS/100mL, nominal concentration of AB26 - 80 mg/LCS No.4: 0.6 mL SS/100mL, nominal concentration of AB26 - 100 mg/L SAMPLE SOLUTION0.4 mL of SS was pipetted into a 100 mL volumetric flask and replenished to the volume with a buffered solution of certain pH (4.0, 7.0, or 9.0) – in duplicate. A nominal concentration of 64 mg/L was prepared for preliminary test (Tier 1).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.OTHER TEST CONDITIONS - Adjustment of pH: The actual pH value of each buffer was measured. The pH-meter calibrated to buffer solutions CertiPUR was used.

Duration:

5.97 d

pH:

4.06

Temp.:

50 °C

Duration:

5.97 d

pH:

6.98

Temp.:

50 °C

Duration:

5.97 d

pH:

8.84

Temp.:

50 °C

Number of replicates:

2 replicates

Positive controls:

no

Negative controls:

no

Preliminary study:

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.

Transformation products:

no

% Recovery:

> -7.2 - < -6.5

pH:

4.06

Temp.:

50 °C

Duration:

5.97 d

% Recovery:

> -4.4 - < -0.7

pH:

6.98

Temp.:

50 °C

Duration:

5.97 d

% Recovery:

> -9.8 - < -1.4

pH:

8.84

Temp.:

50 °C

Duration:

5.97 d

Key result

pH:

4.06

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

6.98

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

8.84

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Details on results:

TEST CONDITIONS - pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes

Table 1: Summary of results - Tier 1

Date	Day	pH 4.06 at 50°C		pH 6.98 at 50°C		pH 8.84 at 50°C
		1	2	1	2	1	2
9.8.2016	0 – start	0.0%	0.0%	0.0%	0.0%	0.0%	0.0%
10.8.2016	0.8	-8.2%	-7.1%	-1.5%	-3.5%	-8.5%	1.1%
11.8.2016	1.92	-6.0%	-6.0%	1.5%	-2.6%	-7.9%	2.4%
12.8.2016	2.78	-3.3%	-5.9%	0.4%	-3.7%	-9.2%	3.1%
14.8.2016	4.96	-7.0%	-5.2%	1.0%	-2.8%	-8.2%	1.2%
15.8.2016	5.97	-6.5%	-7.2%	-0.7%	-4.4%	-9.8%	-1.4%

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 (see Table 1), 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

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.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C