N,N'-(methylenedi-p-phenylene)bis(aziridine-1-carboxamide)

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 December 2017 - 14 March 2018

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)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling method:
Tier I: Before the solutions were placed in the incubator, the samples of them were taken out, signed as “Day 0” samples. After 5 days, the next samples were taken from the examined testing solutions (pH 4, 7 and 9, 50 ºC). Duplicate samples were taken at each pH.
Tier II: The test was conducted until 90% hydrolysis was observed (pH 4, 7 and 9, at 20, 30 and 50ºC).
Tier III: In order to identify the hydrolysis products a sampling was performed after 1 hour of hydrolysis (pH 4 at 30 ºC).
- Sampling intervals/times for pH measurements:
Tier I: Duplicate samples at each pH were taken at day 0 and day 5.
Tier II: One sample at 0 hours and 6-8 consecutive samples until 90% hydrolysis were taken depending on rate of hydrolysis.
Tier III: One sample at 1 hour

Buffers:

Buffers solutions from Avantor Performance Materials Poland S.A. at three values: pH 4.0; pH 7.0 and pH 9.0

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks: glass flasks fitted with glass stoppers
- Other equipment used: incubator and magnetic stirrer

TEST MEDIUM
- Preparation of test medium:
Tier I: 1 mL of tested sample was added to 10mL volumetric flask, exactly weighed, next was diluted with methanol and filled with methanol up to the mark.
Tier II: 1 mL of tested sample was added to 5mL volumetric flask, exactly weighed, next was diluted with methanol and filled with methanol up to the mark.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

1.3 mg/L

Remarks:

Tier 1

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

0.8 mg/L

Remarks:

Tier 1

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

2.8 mg/L

Remarks:

Tier 1

Duration:

2 h

pH:

4

Temp.:

20 °C

Initial conc. measured:

2.6 mg/L

Remarks:

Tier 2

Duration:

1.9 h

pH:

4

Temp.:

30 °C

Initial conc. measured:

3.7 mg/L

Remarks:

Tier 2

Duration:

1.3 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

5.1 mg/L

Remarks:

Tier 2

Duration:

23.5 h

pH:

7

Temp.:

20 °C

Initial conc. measured:

11.1 mg/L

Remarks:

Tier 2

Duration:

21 h

pH:

7

Temp.:

30 °C

Initial conc. measured:

8.9 mg/L

Remarks:

Tier 2

Duration:

3.6 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

12.2 mg/L

Remarks:

Tier 2

Duration:

123.5 h

pH:

9

Temp.:

20 °C

Initial conc. measured:

4.9 mg/L

Remarks:

Tier 2

Duration:

51.8 h

pH:

9

Temp.:

30 °C

Initial conc. measured:

4 mg/L

Remarks:

Tier 2

Duration:

3.8 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

5.4 mg/L

Remarks:

Tier 2

Duration:

1 h

pH:

4

Temp.:

30 °C

Remarks:

Tier 3

Number of replicates:

Preliminary test Tier 1: two replicates
Tier 2 and Tier 3: no replicates.

Positive controls:

no

Negative controls:

no

Statistical methods:

The statistical calculations and the graphs were performed using SigmaPlot 9.0 software of SYSTAT Software, Inc., USA purchased from GAMBIT CoiS Ltd, Poland.

Preliminary study:

After 5 days study it was stated that the test item was not hydrolytically stable. Increase in concentration loss was more than 10 % at three pH values: 4.0; 7.0 and 9.0 and further testing was necessary.

Test performance:

Measurement in buffer solution at pH 4.0 and 20ºC: The determined rate constant after 2 hours at 20ºC (calculated by regression analysis) was equal 1.267 h-1 and the half-life period was 0.55 h.
Measurement in buffer solution at pH 4.0 and 30ºC: The determined rate constant after 1.9 hours at 30ºC (calculated by regression analysis) was equal 1.271 h-1 and the half-life period was 0.55 h.
Measurement in buffer solution at pH 4.0 and 50ºC: The determined rate constant after 1.3 hours at 50ºC (calculated by regression analysis) was equal 2.136 h-1 and the half-life period was 0.32 h.
Measurement in buffer solution at pH 7.0 and 20ºC: The determined rate constant after 23.5 hours at 20ºC (calculated by regression analysis) was equal 0.126 h-1 and the half-life period was 5.5 h.
Measurement in buffer solution at pH 7.0 and 30ºC: The determined rate constant after 21 hours at 30ºC (calculated by regression analysis) was equal 0.128 h-1 and the half-life period was 5.41 h.
Measurement in buffer solution at pH 7.0 and 50ºC: The determined rate constant after 3.6 hours at 50ºC (calculated by regression analysis) was equal 0.687 h-1 and the half-life period was 1.01 h.
Measurement in buffer solution at pH 9.0 and 20ºC: The determined rate constant after 123.5 hours at 20ºC (calculated by regression analysis) was equal 0.0164 h-1 and the half-life period was 42.26 h.
Measurement in buffer solution at pH 9.0 and 30ºC: The determined rate constant after 51.8 hours at 30ºC (calculated by regression analysis) was equal 0.0469 h-1 and the half-life period was 14.78 h.
Measurement in buffer solution at pH 9.0 and 50ºC: The determined rate constant after 3.8 hours at 50ºC (calculated by regression analysis) was equal 0.629 h-1 and the half-life period was 1.10 h.

Transformation products:

yes

No.:

#1

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

The major hydrolysis product of retention time equals 17.6 min was identified as tributyl acetylcitrate.

% Recovery:

7.7

pH:

4

Temp.:

20 °C

Duration:

2 h

% Recovery:

8.1

pH:

4

Temp.:

30 °C

Duration:

1.9 h

% Recovery:

9.8

pH:

4

Temp.:

50 °C

Duration:

1.3 h

% Recovery:

6.3

pH:

7

Temp.:

20 °C

Duration:

23.5 h

% Recovery:

9

pH:

7

Temp.:

30 °C

Duration:

21 h

% Recovery:

7.4

pH:

7

Temp.:

50 °C

Duration:

3.6 h

% Recovery:

10.2

pH:

9

Temp.:

20 °C

Duration:

123.5 h

% Recovery:

10

pH:

9

Temp.:

30 °C

Duration:

51.8 h

% Recovery:

9.3

pH:

9

Temp.:

50 °C

Duration:

3.8 h

Key result

pH:

4

Temp.:

20 °C

Hydrolysis rate constant:

1.267 h-1

DT50:

0.55 h

Type:

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

Key result

pH:

4

Temp.:

30 °C

Hydrolysis rate constant:

1.271 h-1

DT50:

0.55 h

Type:

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

Key result

pH:

4

Temp.:

50 °C

Hydrolysis rate constant:

2.136 h-1

DT50:

0.32 h

Type:

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

Key result

pH:

7

Temp.:

20 °C

Hydrolysis rate constant:

0.126 h-1

DT50:

5.5 h

Type:

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

Key result

pH:

7

Temp.:

30 °C

Hydrolysis rate constant:

0.128 h-1

DT50:

5.41 h

Type:

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

Key result

pH:

7

Temp.:

50 °C

Hydrolysis rate constant:

0.687 h-1

DT50:

1.01 h

Type:

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

Key result

pH:

9

Temp.:

20 °C

Hydrolysis rate constant:

0.016 h-1

DT50:

42.26 h

Type:

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

Key result

pH:

9

Temp.:

30 °C

Hydrolysis rate constant:

0.047 h-1

DT50:

14.78 h

Type:

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

Key result

pH:

9

Temp.:

50 °C

Hydrolysis rate constant:

0.629 h-1

DT50:

1.1 h

Type:

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

Key result

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

1.3 h-1

DT50:

0.53 h

Remarks on result:

other: calculated

Key result

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

0.138 h-1

DT50:

5.023 h

Remarks on result:

other: calculated

Key result

pH:

9

Temp.:

25 °C

Hydrolysis rate constant:

0.029 h-1

DT50:

23.58 h

Remarks on result:

other: calculated

Details on results:

TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes, pH and temperature were set and maintaned at various fixed values.

MAJOR TRANSFORMATION PRODUCTS
- At pH4:1 after 1 hour incubation at 30ºC: tributyl acetylcitrate

Preliminary test (Tier I)

Measurements in buffer solution at pH 4.0 at 50ºC

Time, days		0	5
concentration, [mg/L]	1	1.3	0.1
	2	1.3	0.1
average concentration, [mg/L]		1.3	0.1
concentration loss,  [%]		92.3

Measurements in buffer solution at pH 7.0 at 50ºC

Time, days		0	5
concentration, [mg/L]	1	0.7	0.1
	2	0.9	0.1
average concentration,  [mg/L]		0.8	0.1
concentration loss,  [%]		87.5

Measurements in buffer solution at pH 9.0 at 50ºC

Time, days		0	5
concentration, [mg/L]	1	3.0	0.1
	2	2.5	0.1
average concentration, [mg/L]		2.8	0.1
concentration loss,  [%]		96.4

Tier II

Measurements in buffer solution at pH 4.0 and 20ºC

Time, hours	0	0.5	1.0	1.2	1.4	1.7	2.0
concentration, [mg/mL]	2.6	1.6	0.6	0.5	0.4	0.4	0.2
concentration loss,  [%]	0	0.4	76.9	80.8	84.6	84.6	92.3

 

Measurements in buffer solution at pH 4.0 and 30ºC

Time, hours	0	0.4	0.6	0.9	1.3	1.9
concentration, [mg/mL]	3.7	2.0	1.3	1.3	0.9	0.3
concentration loss,  [%]		46.0	64.9	64.9	75.7	91.9

Measurements in buffer solution at pH 4.0 and 50ºC

Time, hours	0	0.7	0.8	0.9	1.0	1.3
concentration, [mg/mL]	5.1	0.9	0.7	0.6	0.6	0.5
concentration loss,  [%]		82.4	86.3	88.2	88.2	90.2

Measurements in buffer solution at pH 7.0 and 20ºC

Time, hours	0	3.2	3.9	4.7	5.7	6.4	23.5
concentration, [mg/mL]	11.1	6.3	6.1	6.0	4.7	4.3	0.7
concentration loss,  [%]		43.2	45.1	46.0	57.7	61.3	93.7

Measurements in buffer solution at pH 7.0 and 30ºC

Time, hours	0	1.9	2.9	4.9	5.8	7.5	21
concentration, [mg/mL]	8.9	5.4	4.6	3.2	3.1	3.0	0.8
concentration loss,  [%]		39.3	48.3	64.0	65.2	66.3	91.0

Measurements in buffer solution at pH 7.0 and 50ºC

Time, hours	0	1.0	1.8	2.3	2.8	3.2	3.6
concentration, [mg/mL]	12.2	5.2	4.6	2.8	2.2	1.1	0.9
concentration loss,  [%]		57.4	62.3	77.1	82.0	91.0	92.6

Measurements in buffer solution at pH 9.0 and 20ºC

Time, hours	0	5.8	7.3	8.5	9.5	20.8	26.2	96.5	123.5
concentration, [mg/mL]	4.9	3.8	3.4	2.8	2.7	2.7	2.4	1.8	0.5
concentration loss,  [%]		22.5	30.6	42.9	44.9	44.9	51.0	63.3	89.8

Measurements in buffer solution at pH 9.0 and 30ºC

Time, hours	0	1.0	21.8	25.2	27.3	45.8	51.8
concentration, [mg/mL]	4.0	3.8	1.2	1.1	1.0	0.5	0.4
concentration loss,  [%]		5.0	70.0	72.5	75.0	87.5	90.0

Measurements in buffer solution at pH 9.0 and 50ºC

Time, hours	0	0.8	1.7	2.2	2.7	3.4	3.8
concentration, [mg/mL]	5.4	4.0	1.9	1.5	0.9	0.6	0.5
concentration loss, [%]		25.9	64.8	72.2	83.3	88.9	90.7

Hydrolysis rate constant k, half-live period t0.5 and activation energy E values

	pH 4	pH 7	pH 9
20^oC (experimental)	kobs= 1.267 h^-1 t0.5= 0.55 h	kobs= 0.126 h^-1 t0.5= 5.5 h	kobs= 0.0164 h^-1 t0.5= 42.26 h
25^oC (calculated)	kcalc= 1.30 h^-1	kcalc= 0.138	kcalc= 0.0294
30^oC (experimental)	kobs =1.271 h^-1 t0.5= 0.55 h	kobs =0.128h^-1 t0.5= 5.41 h	kobs =0.0469 h^-1 t0.5= 14.78 h
50^oC (experimental)	kobs =2.136 h^-1 t0.5= 0.32 h	kobs =0.687 h^-1 t0.5= 1.01 h	kobs =0.629 h^-1 t0.5= 1.10 h
Activation energy E, kJ/mol	14.596 kJ/mol	47.372	96.844

Validity criteria fulfilled:

yes

Remarks:

Selectivity: no other peaks interfering with the substance peak; linearity: R2 > 0.99; precision RSD 0.32% (approval criteria < 4.48%) and RSD for repeatibility was 1.19% (approval criteria < 1.34%)

Conclusions:

The substance was found to be hydrolitically unstable at pH 4.0 (20-50ºC), pH 7.0 (20-50ºC) and pH 9.0 (50ºC) with half-life <6h, being more stable at ph 9.0 (20 and 30ºC) with half-life >12h. The major hydrolysis product was identified as tributyl acetylcitrate.

Executive summary:

An Hydrolysis study was conducted on the test substance, according to OECD TG 111 (Hydrolysis as a function of pH), GLP Study. A validated HPLC method was used for determining the content of the test substance in the samples. This method was based on the separation of the individual components in the sample and the determination of their contents by comparison with the external calibration. A preliminary test (Tier 1) was conducted at pH 4.0, 7.0 and 9.0 at 50ºC, which showed that about 90% of the substance was hydrolyzed after 5 days at every pH, so further testing was necessary. At pH=4, the hydrolysis rate constants were found to be 1.267 h-1(20ºC), 1.271 h-1(30ºC) and 2.136 h-1 (50ºC) and the half-lives 0.55 h(20ºC), 0.55h (30ºC) and 0.32 h (50ºC). At pH=7, the hydrolysis rate constants were found to be 0.126 h-1(20ºC), 0.128 h-1(30ºC) and 0.687 h-1 (50ºC) and the half-lives 5.5 h(20ºC), 5.41h (30ºC) and 1.01 h (50ºC). At pH=9, the hydrolysis rate constants were found to be 0.0164 h-1(20ºC), 0.0469 h-1(30ºC) and 0.629 h-1 (50ºC) and the half-lives 42.26 h(20ºC), 14.78h (30ºC) and 1.10 h (50ºC). The calculated rate constants at 25ºC were found to be 1.30 h-1 at pH=4, 0.138 h-1 at pH=7 and 0.0294 at pH=9. A third assay was made for identifying the major hydrolysis product by coupling selective mass detector to a chromatograph. The major hydrolysis product was identified as tributyl acetylcitrate. On the basis of these results, the substance was considered hydrolitically unstable at pH 4.0 (20-50ºC), pH 7.0 (20-50ºC) and pH 9.0 (50ºC) with half-life <6h, being more stable at ph 9.0 (20 and 30ºC) with half-life >12h.

Description of key information

Key study. Method according to OECD 111, GLP Study. The substance is hydrolitically unstable at pH 4.0 (20-50ºC), pH 7.0 (20-50ºC) and pH 9.0 (50ºC) with half-life <6h, being more stable at ph 9.0 (20 and 30ºC) with half-life >12h. The hydrolysis rate constants at 25ºC were found to be 1.30 h-1 at pH=4, 0.138 h-1 at pH=7 and 0.0294 at pH=9 and the related half-lives were calculated to be 0.53 h at pH=4, 5.023 h at pH=7 and 23.58 h at pH=9. The major hydrolysis product was identified as tributyl acetylcitrate.

Key value for chemical safety assessment

Half-life for hydrolysis:

23.58 h

at the temperature of:

25 °C

Additional information

An Hydrolysis study was conducted on the test substance, according to OECD TG 111 (Hydrolysis as a function of pH), GLP Study. A validated HPLC method was used for determining the content of the test substance in the samples. This method was based on the separation of the individual components in the sample and the determination of their contents by comparison with the external calibration. A preliminary test (Tier 1) was conducted at pH 4.0, 7.0 and 9.0 at 50ºC, which showed that about 90% of the substance was hydrolyzed after 5 days at every pH, so further testing was necessary. At pH=4, the hydrolysis rate constants were found to be 1.267 h-1(20ºC), 1.271 h-1(30ºC) and 2.136 h-1 (50ºC) and the half-lives 0.55 h(20ºC), 0.55h (30ºC) and 0.32 h (50ºC). At pH=7, the hydrolysis rate constants were found to be 0.126 h-1(20ºC), 0.128 h-1(30ºC) and 0.687 h-1 (50ºC) and the half-lives 5.5 h(20ºC), 5.41h (30ºC) and 1.01 h (50ºC). At pH=9, the hydrolysis rate constants were found to be 0.0164 h-1(20ºC), 0.0469 h-1(30ºC) and 0.629 h-1 (50ºC) and the half-lives 42.26 h(20ºC), 14.78h (30ºC) and 1.10 h (50ºC). The calculated rate constants at 25ºC were found to be 1.30 h-1 at pH=4, 0.138 h-1 at pH=7 and 0.0294 at pH=9. A third assay was made for identifying the major hydrolysis product by coupling selective mass detector to a chromatograph. The major hydrolysis product was identified as tributyl acetylcitrate. On the basis of these results, the substance was considered hydrolitically unstable at pH 4.0 (20-50ºC), pH 7.0 (20-50ºC) and pH 9.0 (50ºC) with half-life <6h, being more stable at ph 9.0 (20 and 30ºC) with half-life >12h.