4-[(1-amino-9,10-dihydro-4-hydroxy-9,10-dioxo-2-anthryl)oxy]-N-(3-ethoxypropyl)benzenesulphonamide

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

6 September 2016 and 31 January 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)

Remarks:

OECD GLP

Specific details on test material used for the study:

Identification: FAT 40444/B TE
Appearance/Physical state: Dark red powder
Batch:PCR92X140707 (China)
Purity: 95.4 %
Expiry date: 14 October 2019
Storage conditions: Approximately 4 °C, in the dark

Test item was stored at room temperature between 14th and 18th March 2016, before transferring to 4 °C on sponsor’s authority. No impact to test item.

Radiolabelling:

not specified

Analytical monitoring:

yes

Details on sampling:

The sample solutions were taken from the waterbath at various times and the pH of each solution recorded.
The concentration of the sample solution was determined by high performance liquid chromatography (HPLC).

Samples
Duplicate aliquots (A and B) of each sample solution were diluted by a factor of 10 using acetonitrile.

Standards
Duplicate standard solutions of test item were prepared in relevant buffer: acetonitrile (1:9 v/v) at a nominal concentration of 0.35 mg/L.

Matrix blanks
Relevant buffer: acetonitrile (1:9 v/v)

Buffers:

The test system consisted of sterile buffer solutions at pH’s 4, 7 and 9.

Buffer solution (pH) Components Concentration (mol dm-3)
4 Citric acid 0.006
Sodium chloride 0.004
Sodium hydroxide 0.007
7 Disodium hydrogen orthophosphate (anhydrous) 0.003
Potassium dihydrogen orthophosphate 0.002
Sodium chloride 0.002
9 Disodium tetraborate 0.001
Sodium chloride 0.002

These solutions were subjected to ultrasonication and degassing with nitrogen to minimize dissolved oxygen content.

Details on test conditions:

Preparation of the Test Solutions
Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 3.5 mg/L in the three buffer solutions. A 1% co-solvent of acetonitrile was used to aid solubility.
The test solutions were split into individual vessels for each data point.
The solutions were shielded from light whilst maintained at the test temperature.

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 or more hours.

Tier 2
Results from the Preliminary test/Tier 1 showed it was necessary to undertake further 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 for a periods outlined in the following table.
Additional testing was also carried out at pH 4, 7 and 9, with solutions being maintained at 25.0 ± 0.5 °C for approximately 30 days, using silanised glassware.

Test pH Test Temperature Sample Timings
4 50.0 ± 0.5 °C Initial to 360 hours
4 60.0 ± 0.5 °C Initial to 168 hours
4 70.0 ± 0.5 °C Initial to 240 hours
7 50.0 ± 0.5 °C Initial to 240 hours
7 60.0 ± 0.5 °C Initial to 120 hours
7 70.0 ± 0.5 °C Initial to 72 hours
9 50.0 ± 0.5 °C Initial to 696 hours
9 60.0 ± 0.5 °C Initial to 360 hours
9 70.0 ± 0.5 °C Initial to 144 hours

Duration:

360 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

3.5 mg/L

Duration:

168 h

pH:

4

Temp.:

60 °C

Initial conc. measured:

3.5 mg/L

Duration:

240 h

pH:

4

Temp.:

70 °C

Initial conc. measured:

3.5 mg/L

Duration:

240 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

3.5 mg/L

Duration:

120 h

pH:

7

Temp.:

60 °C

Initial conc. measured:

3.5 mg/L

Duration:

72 h

pH:

7

Temp.:

70 °C

Initial conc. measured:

3.5 mg/L

Duration:

696 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

3.5 mg/L

Duration:

360 h

pH:

9

Temp.:

60 °C

Initial conc. measured:

3.5 mg/L

Duration:

144 h

pH:

9

Temp.:

70 °C

Initial conc. measured:

3.5 mg/L

Duration:

30 d

pH:

4

Temp.:

25 °C

Initial conc. measured:

3.5 mg/L

Duration:

30 d

pH:

7

Temp.:

25 °C

Initial conc. measured:

3.5 mg/L

Duration:

30 d

pH:

9

Temp.:

25 °C

Initial conc. measured:

3.5 mg/L

Positive controls:

not specified

Negative controls:

not specified

Preliminary study:

The extent of hydrolysis after 120 h at pH 4 indicated that a further test (Tier 2) was required to estimate the rate constant and half-life at 25 °C.
The extent of hydrolysis after 120 h at pH 7 indicated that a further test (Tier 2) was required to estimate the rate constant and half-life at 25 °C.
The extent of hydrolysis after 216 h at pH 9 indicated that a further test (Tier 2) was required to estimate the rate constant and half-life at 25 °C.

Test performance:

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0.03 to 1.0 mg/L for pH 4, 7 and 9. The results were satisfactory with correlation coefficients (r) of ≥0.999 being obtained for all pH’s.

Transformation products:

not specified

Remarks on result:

not determinable

Remarks:

Pseudo first order kinetics were not observed during testing at elevated temperatures or directly at 25 °C. There was no clear signs of consistent hydrolysis. Therefore, it can be concluded that any losses in test item were due to a mechanism other than hydrolysis. Due to this no hydrolysis rate could be determined.

Details on results:

No significant peaks were observed at the approximate retention time of the test item on analysis of any matrix blank solutions. The hydrolysis was carried out at elevated temperatures (50, 60 and 70 °C). Due to the inconsistencies with the hydrolysis with temperature and pH, additional testing was carried out directly at 25 °C, for one month, as recommended by the guidelines, in silanized glassware. In addition to this, hydrolysis testing was also carried out at 25 °C for all pH’s using a single vessel, sampling at each time point. The half-life data from the duplicate vessel analysis and the single vessel analysis were consistent. Pseudo first order kinetics were not observed due to high variability in analysis results, this also produced poor correlation in Arrhenius plots.
During all the testing there was no clear signs of consistent hydrolysis. Therefore, it can be concluded that any losses in test item were due to a mechanism other than hydrolysis.
Due to this no hydrolysis rate could be determined. The amount remaining after 30 days at 25 °C is shown in the table below, however, the results are not considered to be due to hydrolysis.

pH % remaining after 29 days % remaining after 32 days
4 67.7 18.1
7 45.7 61.3
9 85.5 61.8

Validity criteria fulfilled:

not applicable

Conclusions:

Pseudo first order kinetics were not observed during testing at elevated temperatures or directly at 25 °C. There was no clear signs of consistent hydrolysis. Therefore, it can be concluded that any losses in test item were due to a mechanism other than hydrolysis. Due to this no hydrolysis rate could be determined.

Executive summary:

The assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C.7 and OECD Guideline 111. Pseudo first order kinetics were not observed during testing at elevated temperatures or directly at 25 °C. There was no clear signs of consistent hydrolysis. Therefore it can be concluded that any losses in test item were due to a mechanism other than hydrolysis. Due to this no hydrolysis rate could be determined. Adsorption Coefficient. 4.27 x 10⁵, log₁₀, Koc >5.63, using the HPLC screening method.

Description of key information

The assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C.7 and OECD Guideline 111. Pseudo first order kinetics were not observed during testing at elevated temperatures or directly at 25 °C. There was no clear signs of consistent hydrolysis. Therefore, it can be concluded that any losses in test item were due to a mechanism other than hydrolysis. Due to this no hydrolysis rate could be determined. Adsorption Coefficient. 4.27 x 10⁵, log₁₀ Koc >5.63, using the HPLC screening method.