Disodium 1-amino-4-[[4-[(2-bromo-1-oxoallyl)amino]-2-sulphonatophenyl]amino]-9,10-dihydro-9,10-dioxoanthracene-2-sulphonate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 Oct 2016 to 19 Jan 2017

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:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Identification: FAT 92349/B TE
- Appearance/Physical state: Blue solid
- Batch: 26/2014 (Thailand)
- Purity: 85.5 %
- Expiry date: 16 December 2019
- Storage conditions: Approximately -20 °C, in the dark.

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The sample solutions were taken from the waterbath at various times and the pH of each solution recorded.

Buffers:

pH 4: Components Concentration (mol d/m3)
Citric acid 0.006
Sodium chloride 0.004
Sodium hydroxide 0.007

pH 7:
Disodium hydrogen orthophosphate (anhydrous) 0.003
Potassium dihydrogen orthophosphate 0.002
Sodium chloride 0.002

pH 9:
Disodium tetraborate 0.001
Sodium chloride 0.002

Duration:

120 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

6 g/L

Remarks:

Preliminary test / Tier 1

Duration:

120 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

6 g/L

Remarks:

Preliminary test / Tier 1

Duration:

120 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

6 g/L

Remarks:

Preliminary test / Tier 1

Duration:

336 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

6 g/L

Remarks:

Tier 2

Duration:

192 h

pH:

4

Temp.:

60 °C

Initial conc. measured:

6 g/L

Remarks:

Tier 2

Duration:

168 h

pH:

4

Temp.:

70 °C

Initial conc. measured:

6 g/L

Remarks:

Tier 2

Duration:

192 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

6 g/L

Remarks:

Tier 2

Duration:

192 h

pH:

7

Temp.:

60 °C

Initial conc. measured:

6 g/L

Remarks:

Tier 2

Duration:

192 h

pH:

7

Temp.:

70 °C

Initial conc. measured:

6 g/L

Remarks:

Tier 2

Duration:

600 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

6 g/L

Remarks:

Tier 2

Duration:

600 h

pH:

9

Temp.:

60 °C

Initial conc. measured:

6 g/L

Remarks:

Tier 2

Duration:

360 h

pH:

9

Temp.:

70 °C

Initial conc. measured:

6 g/L

Remarks:

Tier 2

Preliminary study:

The extent of hydrolysis after 120 hours indicated that further testing (Tier 2) may be required as there was inconsistencies between the concentration calculated and the rate of degradation of the peak area of the samples. Therefore, additional testing was carried out to estimate the rate constant and half-life at 25 °C.

Transformation products:

not measured

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

Usually, hydrolysis products should be identified using LC-MS or GC-MS. However, this procedure implies sufficient separation of the individual components that are present in the incubated test item solution (i.e. parent compound and hydrolysis products).
The chromatography of the incubated test item solution resulted in several peaks that could not be separated sufficiently from each other. Thus, identification of the hydrolysis products was technically not feasible. The chemical structure of the hydrolysis product(s) is most probably quite similar to the one of the parent compound.

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Type:

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

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Type:

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

pH:

9

Temp.:

25 °C

Hydrolysis rate constant:

0 h-1

DT50:

230 d

Type:

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

The Arrhenius plot was constructed using the data shown in the following tables:

pH 4 Arrhenius Data

No data could be extrapolated for an Arrhenius plot due to the lack of hydrolysis.

Half-life at 25 °C has been estimated at >1 year, corresponding to the >1 year results at elevated temperatures.

pH 7 Arrhenius Data

The data corresponding to the Arrhenius plot for pH 7 showed that at 50.0 ± 0.5 °C less than 10 % hydrolysis occurred in 168 hours. Therefore, it can be concluded that the half-life at 25 °C has been estimated at >1 year, corresponding to the >1 year results at this elevated temperatures.

pH 9 Arrhenius Data

T (ºC)	T (K)	1/T (K)	kobs (hr-1)	Ln kobs
50	323.2	3.09 x 10^-3	4.06 x 10^-4	-7.81
60	333.2	3.00 x 10^-3	6.21 x 10^-4	-7.39
70	343.2	2.91 x 10^-3	9.19 x 10^-4	-6.99

From the graph of the above data, the rate constant and half-life at 25 °C have been estimated to be as follows:

k_obs = 1.26 x 10^-4 hour^-1

t_½ = 5.52 x 10³ hours = 230 days

Validation

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 50 to 1100 mg/L under pH 4, 7 and 9 conditions. The results were satisfactory with correlation coefficients (r) of ≥ 0.999 being obtained for all pH’s tested.

Validity criteria fulfilled:

yes

Conclusions:

The dissipation half-life for the test substance was estimated to be >1 year at pH 7 and 25 °C .

Executive summary:

Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with EU Method C.7 and OECD Guideline 111. In the preliminary test (Tier 1), sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 120 hours. The extent of hydrolysis after 120 hours indicated that further testing (Tier 2) was required as there was inconsistencies between the concentration calculated and the rate of degradation of the peak area of the samples. Therefore additional testing was carried out to estimate the rate constant and half-life at 25 °C. Tier 2 consisted testing at pH 4, 7 and 9, with solutions being maintained at 50.0 ± 0.5 °C, 60.0 ± 0.5 °C and 70.0 ± 0.5 °C. At pH 4, no data could be extrapolated for an Arrhenius plot due to the lack of hydrolysis. Half-life at 25 °C has been estimated at > 1 year, corresponding to the >1 year results at elevated temperatures. The data corresponding to the Arrhenius plot for pH 7 showed that at 50.0 ± 0.5 °C less than 10 % hydrolysis occurred in 168 hours. Therefore it can be concluded that the half-life at 25 °C has been estimated at >1 year, corresponding to the >1 year results at this elevated temperatures. From the data corresponding to the Arrhenius plot for pH 9, the rate constant and half-life at 25 °C were estimated to be 1.26 x 10^-4 hour^-1 and 230 days, respectively.

Description of key information

Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with EU Method C.7 and OECD Guideline 111. In the preliminary test (Tier 1), sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 120 hours. The extent of hydrolysis after 120 hours indicated that further testing (Tier 2) was required as there was inconsistencies between the concentration calculated and the rate of degradation of the peak area of the samples. Therefore, additional testing was carried out to estimate the rate constant and half-life at 25 °C. Tier 2 consisted testing at pH 4 pH 7 and pH 9, with solutions being maintained at 50.0 ± 0.5 °C, 60.0 ± 0.5 °C and 70.0 ± 0.5 °C. At pH 4, no data could be extrapolated for an Arrhenius plot due to the lack of hydrolysis. Half-life at 25 °C has been estimated at > 1 year, corresponding to the >1 year results at elevated temperatures. The data corresponding to the Arrhenius plot for pH 7 showed that at 50.0 ± 0.5 °C less than 10 % hydrolysis occurred in 168 hours. Therefore, it can be concluded that the half-life at 25 °C has been estimated at >1 year, corresponding to the >1 year results at this elevated temperatures. From the data corresponding to the Arrhenius plot for pH 9, the rate constant and half-life at 25 °C were estimated to be 1.26 x 10^-4 hour^-1and 230 days, respectively.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C