Bis[(3,4-epoxycyclohexyl)methyl] adipate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26 October 2017 to 08 December 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)

Version / remarks:

2004

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:

- For the determination of the concentrations of the test material in the different measuring cylinders at different time intervals, samples were taken under nitrogen atmosphere and measured undiluted by means of HPLC with UV-detection.
- Whenever samples were measured also standard solutions freshly prepared from the test material in acetonitrile and blank buffer solutions were measured for verification of the analytical method

Buffers:

- The buffer solutions used for pH 4, 7 and 9 were:
pH 4: acetic acid (0.05 mol/L) / sodium acetate (0.01 mol/L) 1:1 v/v

pH 7:
Solution A: potassium dihydrogen phosphate (0.07 mol/L).
Solution B: di-potassium hydrogen phosphate (0.07 mol/L).
Buffer solution: 306 mL solution B + 194 mL solution A

pH 9: ammoniac 25 % (14 mol/L) / ammonium chloride (0.05 mol/L) 1:1 v/v (adjusted to the pH with HCl (1 mol/L))

- The pH value of each buffer solution was checked with a calibrated pH meter to a precision of 0.1.

Details on test conditions:

- The study was performed in measuring flasks, which were dried in a drying chamber at 200 °C for 48 hours, under dark and sterile conditions (under inert atmosphere) in temperature controlled water baths.
- The test material was dissolved in acetonitrile and applied into the different buffer solutions under nitrogen atmosphere.
- Preliminary test (Tier 1): The preliminary test was carried out at 50 ± 0.5 °C and pH values of 4.0, 7.0 and 9.0, respectively, in duplicate. The concentration of the test material in the test solutions was 332.4 mg/L. Due to the fact that the test material proved to be unstable at all three pH values further kinetic tests (Tier 2) were carried out.
- Hydrolysis of unstable substances (Tier 2): Due to the fact that the test material was unstable at all three pH values further kinetic tests (Tier 2) were carried out at temperatures of 20, 25 and 30 °C. At each pH-value and each temperature at least two parallel tests (a and b) were performed. Each reaction solution was analysed in time intervals, which were set up to allow at least six data points between 10 and 90 % hydrolysis to be measured.

Duration:

5.8 h

pH:

4

Temp.:

20 °C

Initial conc. measured:

>= 289.1 - <= 308.4 mg/L

Duration:

4.8 h

pH:

4

Temp.:

25 °C

Initial conc. measured:

>= 270.9 - <= 293.9 mg/L

Duration:

4 h

pH:

4

Temp.:

30 °C

Initial conc. measured:

>= 297.6 - <= 307.6 mg/L

Duration:

127.1 h

pH:

7

Temp.:

20 °C

Initial conc. measured:

>= 317.1 - <= 320.3 mg/L

Duration:

78.5 h

pH:

7

Temp.:

25 °C

Initial conc. measured:

>= 299.7 - <= 313.9 mg/L

Duration:

79.3 h

pH:

7

Temp.:

30 °C

Initial conc. measured:

>= 274.6 - <= 286.8 mg/L

Duration:

98.7 h

pH:

9

Temp.:

20 °C

Initial conc. measured:

>= 311.7 - <= 314.6 mg/L

Duration:

23.6 h

pH:

9

Temp.:

25 °C

Initial conc. measured:

>= 288.6 - <= 311.9 mg/L

Duration:

23.1 h

pH:

9

Temp.:

30 °C

Initial conc. measured:

>= 297.1 - <= 306.6 mg/L

Number of replicates:

The test was performed in duplicate

Positive controls:

no

Negative controls:

no

Preliminary study:

TIER 1: The preliminary test at pH 4, 7 and 9 was performed at a temperature of 50 °C. Samples were taken and measured after 5 and 101 hours. The nominal start concentration of the test material was 332.4 mg/L. It was observed, that the test material was hydrolysed by more than 10 % at all three pH values after 5 hours. Thus, Tier 2 was performed for all three pH values.

Test performance:

The HPLC-method was checked several times on every day that samples of the tests were taken and measured. The recovery rates of the standard solutions in acetonitrile range from 91.5 to 109.2 % and show a sufficient accuracy of the analytical method.

Transformation products:

not specified

Key result

pH:

4

Temp.:

20 °C

Hydrolysis rate constant:

0.178 h-1

DT50:

3.9 h

Key result

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

0.292 h-1

DT50:

2.4 h

Key result

pH:

4

Temp.:

30 °C

Hydrolysis rate constant:

0.379 h-1

DT50:

1.8 h

Key result

pH:

7

Temp.:

20 °C

Hydrolysis rate constant:

0.01 h-1

DT50:

70.4 h

Key result

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

0.013 h-1

DT50:

52.7 h

Key result

pH:

7

Temp.:

30 °C

Hydrolysis rate constant:

0.018 h-1

DT50:

38.3 h

Key result

pH:

9

Temp.:

20 °C

Hydrolysis rate constant:

0.059 h-1

DT50:

11.9 h

Key result

pH:

9

Temp.:

25 °C

Hydrolysis rate constant:

0.07 h-1

DT50:

10.1 h

Key result

pH:

9

Temp.:

30 °C

Hydrolysis rate constant:

0.069 h-1

DT50:

10 h

Details on results:

TIER 2 (pH 4)
- For the test at pH 4 and 20 °C a nominal concentration of the test material in the buffer solution of 331.8 mg/L was used. The degree of hydrolysis for the tests a and c at the respective sampling times was calculated in comparison to the measured c0-value at t = 0 h. Results can be seen in Table 1. The calculated results of the measurements at pH 4 at 20 °C are:
6a: kobs = 0.168 h^-1, t0.5 = 4.1 h
6b: kobs = 0.187 h^-1, t0.5 = 3.7 h

- For the test at pH 4 and 25 °C a concentration of the test material in the buffer solution of 333.4 mg/L was used. The degree of hydrolysis for the tests a and b at the respective sampling times was calculated in comparison to the measured c0-value at t = 0 h. Results can be seen in Table 2. The results of the measurements at pH 4 at 25 °C are:
14a: kobs = 0.297 h^-1, t0.5 = 2.3 h
14b: kobs = 0.287 h^-1, t0.5 = 2.4 h

- For the test at pH 4 and 30 °C a concentration of the test material in the buffer solution of 333.9 mg/L was used. The degree of hydrolysis for the tests a and b at the respective sampling times was calculated in comparison to the measured c0-value at t = 0 h. Results can be seen in Table 3. The results of the measurements at pH 4 at 30 °C are:
10a: kobs = 0.375 h^-1, t0.5 = 1.8 h
10b: kobs = 0.383 h^-1, t0.5 = 1.8 h

- Calculation of the Arrhenius parameters for pH 4 can be seen in Table 4.

TIER 2 (pH 7)
- For the test at pH 7 and 20 °C a concentration of the test material in the buffer solution of 331.8 mg/L was used. The degree of hydrolysis for the tests a and b at the respective sampling times was calculated in comparison to the measured c0-value at t = 0 h. Results can be seen in Table 5. The results of the measurements at pH 7 at 20 °C are:
7a: kobs = 0.010 h^-1, t0.5 = 69.4 h
7b: kobs = 0.010 h^-1, t0.5 = 71.3 h

- For the test at pH 7 and 25 °C a concentration of the test material in the buffer solution of 333.4 mg/L was used. The degree of hydrolysis for the tests a and b at the respective sampling times was calculated in comparison to the measured c0-value at t = 0 h. Results can be seen in Table 6. The results of the measurements at pH 7 at 25 °C are:
15a: kobs = 0.013 h^-1, t0.5 = 52.9 h
15b: kobs = 0.013 h^-1, t0.5 = 52.5 h

- For the test at pH 7 and 30 °C a concentration of the test material in the buffer solution of 333.9 mg/L was used. The degree of hydrolysis for the tests a and b at the respective sampling times was calculated in comparison to the measured c0-value at t = 0 h. Results can be seen in Table 7. The results of the measurements at pH 7 at 30 °C are:
11a: kobs = 0.018 h^-1, t0.5 = 38.0 h
11b: kobs = 0.018 h^-1, t0.5 = 38.5 h

- Calculation of the Arrhenius parameters for pH 7 can be seen in Table 8.

TIER 2 (pH 9)
- For the test at pH 9 and 20 °C a concentration of the test material in the buffer solution of 331.8 mg/L was used. The degree of hydrolysis for the tests a and b at the respective sampling times was calculated in comparison to the measured c0-value at t = 0 h. Results can be seen in Table 9. The results of the measurements at pH 9 at 20 °C are:
8a: kobs = 0.061 h^-1, t0.5 = 11.4 h
8b: kobs = 0.056 h^-1, t0.5 = 12.4 h

- For the test at pH 9 and 25 °C a concentration of the test material in the buffer solution of 333.4 mg/L was used. The degree of hydrolysis for the tests a and b at the respective sampling times was calculated in comparison to the measured c0-value at t = 0 h. Results can be seen in Table 10. The results of the measurements at pH 9 at 25 °C are:
16a: kobs = 0.068 h^-1, t0.5 = 10.3 h
16b: kobs = 0.071 h^-1, t0.5 = 9.8 h

- For the test at pH 9 and 30 °C a concentration of the test material in the buffer solution of 333.9 mg/L was used. The degree of hydrolysis for the tests a and b at the respective sampling times was calculated in comparison to the measured c0-value at t = 0 h. Results can be seen in Table 11. The results of the measurements at pH 9 at 30 °C are:
21c: kobs = 0.070 h^-1, t0.5 = 9.9 h
12d: kobs = 0.068 h^-1, t0.5 = 10.1 h

- Calculation of the Arrhenius parameters for pH 9 can be seen in Table 12.

Table 1: Results of Tier 2 at pH 4 and 20 °C

Sample no.	t[h]	Measuredct[mg/L]	lnc0/ct	Degree of hydrolysis [%]
6a-0	0	289.1	--	--
6a-1	0.8	256.8	0.119	11.2
6a-2	1.6	241.7	0.179	16.4
6a-3	2.8	186.0	0.441	35.7
6a-4	3.5	167.5	0.546	42.1
6a-5	4.1	146.9	0.677	49.2
6a-6	4.7	136.6	0.750	52.8
6a-7	5.3	126.0	0.830	56.4
6a-8	5.8	114.1	0.929	60.5
6b-0	0	308.4	--	--
6b-1	0.7	261.2	0.166	15.3
6b-2	1.5	232.7	0.282	24.5
6b-3	2.7	179.8	0.539	41.7
6b-4	3.3	159.6	0.659	48.3
6b-5	3.9	139.9	0.791	54.6
6b-6	4.5	126.2	0.894	59.1
6b-7	5.1	121.3	0.933	60.7
6b-8	5.7	103.0	1.097	66.6

Table 2: Results of Tier 2 at pH 4 and 25 °C

Sample no.	t[h]	Measuredct[mg/L]	lnc0/ct	Degree of hydrolysis [%]
14a-0	0.0	270.9	--	--
14a-1	0.8	227.0	0.177	16.2
14a-2	1.3	197.7	0.315	27.0
14a-3	1.8	167.6	0.480	38.1
14a-4	2.3	141.1	0.652	47.9
14a-5	2.8	127.0	0.757	53.1
14a-6	3.3	109.2	0.909	59.7
14a-7	4.8	68.8	1.3710	74.6
14b-0	0.0	293.9	--	--
14b-1	0.5	261.9	0.115	10.9
14b-2	1.0	233.7	0.229	20.5
14b-3	1.5	199.6	0.387	32.1
14b-4	2.0	171.4	0.539	41.7
14b-5	2.5	150.1	0.672	48.9
14b-6	3.0	129.6	0.819	55.9
14b-7	4.5	84.0	1.252	71.4

Table 3: Results of Tier 2 at pH 4 and 30 °C

Sample no.	t[h]	Measuredct[mg/L]	lnc0/ct	Degree of hydrolysis [%]
10a-0	0.0	297.6	--	--
10a-1	0.7	207.2	0.362	30.4
10a-2	1.4	160.0	0.621	46.2
10a-3	1.9	139.8	0.755	53.0
10a-4	2.3	122.6	0.886	58.8
10a-5	2.5	108.6	1.008	63.5
10a-6	2.8	95.3	1.139	68.0
10a-7	3.2	84.6	1.257	71.6
10a-8	4.0	56.7	1.657	80.9
10b-0	0.0	307.6	--	--
10b-1	0.5	209.0	0.387	32.1
10b-2	1.2	163.5	0.632	46.9
10b-3	1.7	140.9	0.781	54.2
10b-4	2.1	128.0	0.877	58.4
10b-5	2.3	107.0	1.056	65.2
10b-6	2.6	97.5	1.149	68.3
10b-7	3.0	84.7	1.290	72.5
10b-8	4.0	55.8	1.707	81.9

Table 4: Calculation of the Arrhenius Parameters for pH 4

T[°C]	T[K]	1/T[1/K]	kobs[h^-1]	lnkobs
20	293.15	0.00341	0.168	-1.786
20	293.15	0.00341	0.187	-1.679
25	298.15	0.00335	0.297	-1.213
25	298.15	0.00335	0.287	-1.248
30	303.15	0.00330	0.375	-0.981
30	303.15	0.00330	0.383	-0.961
lnA	21.4		A[h^-1]	2 x 10^9
-EA/R	-6774.1		EA[kJ/mol]	56.3

Table 5: Results of Tier 2 at pH 7 and 20 °C

Sample no.	t[h]	Measuredct[mg/L]	lnc0/ct	Degree of hydrolysis [%]
7a-0	0.0	317.1	--	--
7a-1*	1.0	307.0	0.032	3.2
7a-2*	2.0	304.8	0.040	3.9
7a-3*	3.0	299.8	0.056	5.5
7a-4*	7.0	298.1	0.062	6.0
7a-5	24.8	261.2	0.194	17.7
7a-6	27.1	252.7	0.227	20.3
7a-7	31.1	246.4	0.253	22.3
7a-8	47.3	189.3	0.516	40.3
7a-9	51.1	180.7	0.562	43.0
7a-10	54.4	168.6	0.562	46.9
7a-11	122.1	95.2	1.203	70.0
7a-12	127.1	92.3	1.234	70.9
7b-0	0.0	320.3	--	--
7b-1*	0.6	309.0	0.036	3.5
7b-2*	1.6	303.1	0.055	5.4
7b-3*	2.6	302.3	0.058	5.6
7b-4*	--	--	--	--
7b-5	24.3	263.2	0.196	17.8
7b-6	26.7	250.4	0.246	21.8
7b-7	30.7	249.7	0.249	22.1
7b-8	46.8	189.9	0.523	40.7
7b-9	50.7	173.7	0.602	45.2
7b-10	54.0	169.4	0.602	46.6
7b-11	121.7	96.3	1.192	69.6
7b-12	126.7	94.6	1.210	70.2

Table 6: Results of Tier 2 at pH 7 and 25 °C

Sample no.	t[h]	Measuredct[mg/L]	lnc0/ct	Degree of hydrolysis* [%]
15a-0	0.0	299.7	--	--
15a-1	23.3	251.3	0.176	16.2
15a-2	27.7	241.3	0.217	19.5
15a-3	31.5	224.8	0.288	25.0
15a-4	47.3	190.5	0.453	36.4
15a-5	51.5	179.9	0.511	40.0
15a-6	55.5	170.1	0.567	43.3
15a-7	71.3	138.0	0.776	54.0
15a-8	75.5	127.3	0.857	57.5
15a-9	78.5	120.2	0.913	59.9
15b-0	0.0	313.9	--	--
15b-1	23.1	250.7	0.225	20.1
15b-2	27.6	239.9	0.269	23.6
15b-3	31.4	225.7	0.330	28.1
15b-4	47.2	185.3	0.527	41.0
15b-5	51.4	177.0	0.573	43.6
15b-6	55.4	167.3	0.629	46.7
15b-7	71.2	133.8	0.853	57.4
15b-8	75.4	127.8	0.899	59.3
15b-9	78.4	120.2	0.960	61.7

Table 7: Results of Tier 2 at pH 7 and 30 °C

Sample no.	t[h]	Measuredct[mg/L]	lnc0/ct	Degree of hydrolysis* [%]
11a-0	0.0	274.6	--	--
11a-1*	2.4	280.1	-0.020	-2.0
11a-2*	7.3	277.5	-0.011	-1.1
11a-3	24.3	211.8	0.260	22.9
11a-4	27.4	196.7	0.333	28.4
11a-5	31.7	182.9	0.406	33.4
11a-6	48.2	143.6	0.648	47.7
11a-7	52.7	127.3	0.769	53.6
11a-8	56.3	121.9	0.813	55.6
11a-9	73.7	86.0	1.160	68.7
11a-10	79.3	75.8	1.287	72.4
11b-0	0.0	286.8	--	--
11b-1*	2.2	466.2	-0.486	-62.6
11b-2*	7.1	277.4	0.033	3.3
11b-3	24.0	218.5	0.272	23.8
11b-4	27.2	203.2	0.345	29.2
11b-5	31.4	189.0	0.417	34.1
11b-6	47.9	146.5	0.672	48.9
11b-7	52.4	134.6	0.756	53.1
11b-8	56.1	125.3	0.828	56.3
11b-9	73.4	90.3	1.156	68.5
11b-10	79.0	79.0	1.290	72.5

*Since the degree of hydrolysis of these samples was below 10 %, the values were not used for further calculations.

Table 8: Calculation of the Arrhenius Parameters for pH 7

T[°C]	T[K]	1/T[1/K]	kobs[h^-1]	lnkobs
20	293.15	0.00341	0.010	-4.61
20	293.15	0.00341	0.010	-4.63
25	298.15	0.00335	0.013	-4.33
25	298.15	0.00335	0.013	-4.33
30	303.15	0.00330	0.018	-4.00
30	303.15	0.00330	0.018	-4.02
lnA	13.8		A[h^-1]	10 x 10^5
-EA/R	-5406.1		EA[kJ/mol]	44.9

Table 9: Results of Tier 2 at pH 9 and 20 °C

Sample no.	t[h]	Measuredct[mg/L]	lnc0/ct	Degree of hydrolysis* [%]
8a-0	0.0	314.6	--	--
8a-1	3.7	257.3	0.201	18.2
8a-2	6.0	241.3	0.265	23.3
8a-3	7.7	222.3	0.347	29.3
8a-4	23.8	74.2	1.444	76.4
8a-5	25.8	67.3	1.542	78.6
8a-6	27.7	60.7	1.644	80.7
8a-7	31.0	56.1	1.724	82.2
8a-8*	98.7	0.0	--	100.0
8b-0	0.0	311.7	--	--
8b-1	3.2	258.5	0.187	17.1
8b-2	5.5	246.0	0.237	21.1
8b-3	7.2	224.1	0.330	28.1
8b-4	23.3	80.9	1.348	74.0
8b-5	25.3	76.3	1.408	75.5
8b-6	27.2	71.1	1.477	77.2
8b-7	30.5	62.9	1.600	79.8
8b-8*	98.2	0.0	--	100.0

*Since the degree of hydrolysis of these samples was at 100 %, the values were not used for further calculations.

Table 10: Results of Tier 2 at pH 9 and 25 °C

Sample no.	t[h]	Measuredct[mg/L]	lnc0/ct	Degree of hydrolysis* [%]
16a-0	0.0	288.6	--	--
16a-1	2.8	239.8	0.185	16.9
16a-2	3.8	220.4	0.270	23.6
16a-3	4.8	209.8	0.319	27.3
16a-4	5.6	196.8	0.383	31.8
16a-5	6.3	186.4	0.437	35.4
16a-6	7.1	177.6	0.486	38.5
16a-7	7.8	167.1	0.546	42.1
16a-8	23.6	58.6	1.594	79.7
16b-0	0.0	311.9	--	--
16b-1	2.7	252.5	0.211	19.0
16b-2	3.7	239.1	0.266	23.3
16b-3	4.7	220.7	0.346	29.2
16b-4	5.4	205.2	0.419	34.2
16b-5	6.2	200.7	0.441	35.7
16b-6	6.9	191.3	0.489	38.7
16b-7	7.7	179.5	0.552	42.4
16b-8	23.4	58.3	1.677	81.3

Table 11: Results of Tier 2 at pH 9 and 30 °C

Sample no.	t[h]	Measuredct[mg/L]	lnc0/ct	Degree of hydrolysis* [%]
12c-0	0.0	297.1	--	--
12c-1	2.5	254.8	0.154	14.3
12c-2	3.8	235.3	0.233	20.8
12c-3	4.6	228.8	0.261	23.0
12c-4	5.1	211.5	0.340	28.8
12c-5	5.6	199.3	0.399	32.9
12c-6	6.1	197.2	0.410	33.6
12c-7	6.8	187.3	0.461	37.0
12c-8	23.1	60.5	1.591	79.6
12d-0	0.0	306.6	--	--
12d-1	2.3	257.8	0.173	15.9
12d-2	3.6	243.7	0.230	20.5
12d-3	4.4	227.2	0.300	25.9
12d-4	4.9	214.1	0.359	30.2
12d-5	5.4	205.3	0.401	33.1
12d-6	5.9	198.2	0.436	35.3
12d-7	6.6	192.3	0.467	37.3
12d-8	22.9	63.3	1.578	79.4

Table 12: Calculation of the Arrhenius Parameters for pH 9

T[°C]	T[K]	1/T[1/K]	kobs[h^-1]	lnkobs
20	293.15	0.00341	0.061	-2.80
20	293.15	0.00341	0.0558	-2.89
25	298.15	0.00335	0.068	-2.70
25	298.15	0.00335	0.071	-2.64
30	303.15	0.00330	0.070	-2.66
30	303.15	0.00330	0.068	-2.68
lnA	7.47		A[h^-1]	1761.9
-EA/R	-3024.4		EA[kJ/mol]	25.1

Validity criteria fulfilled:

yes

Conclusions:

At pH 4 average half-lives were 3.9, 2.4 and 1.8 hours at 20, 25 and 30 °C, respectively. At pH 7 average half-lives were 70.4, 52.7 and 38.3 hours at 20, 25 and 30 °C, respectively. At pH 9 average half-lives were 11.9, 10.1 and 10 hours at 20, 25 and 30 °C, respectively.

Executive summary:

The hydrolysis of the test material as a function of pH was investigated in accordance with the standardised guidelines OECD 111 and EU Method C.7 under GLP conditions.

The preliminary test at pH 4, 7 and 9 was performed at a temperature of 50 °C. Samples were taken and measured after 5 and 101 hours. The nominal start concentration of the test material was 332.4 mg/L. It was observed, that the test material was hydrolysed by more than 10 % at all three pH values after 5 hours. Thus, Tier 2 was performed for all three pH values.

The half-life values of the test material were determined at pH 4, 7 and 9 at 20, 25 and 30 °C using HPLC. The test was performed in duplicate

At pH 4 average half-lives were 3.9, 2.4 and 1.8 hours at 20, 25 and 30 °C, respectively. At pH 7 average half-lives were 70.4, 52.7 and 38.3 hours at 20, 25 and 30 °C, respectively. At pH 9 average half-lives were 11.9, 10.1 and 10 hours at 20, 25 and 30 °C, respectively.

Description of key information

The hydrolysis of the test material as a function of pH was investigated in accordance with the standardised guidelines OECD 111 and EU Method C.7 under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

 

The preliminary test at pH 4, 7 and 9 was performed at a temperature of 50 °C. Samples were taken and measured after 5 and 101 hours. The nominal start concentration of the test material was 332.4 mg/L. It was observed that the test material was hydrolysed by more than 10 % at all three pH values after 5 hours. Thus, Tier 2 was performed for all three pH values.

 

At pH 4 average half-lives were 3.9, 2.4 and 1.8 hours at 20, 25 and 30 °C, respectively. At pH 7 average half-lives were 70.4, 52.7 and 38.3 hours at 20, 25 and 30 °C, respectively. At pH 9 average half-lives were 11.9, 10.1 and 10 hours at 20, 25 and 30 °C, respectively.

 

Key value for chemical safety assessment

Half-life for hydrolysis:

52.7 h

at the temperature of:

25 °C