3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidine-2,5-dione

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-02-05 to 2016-07-04

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:

/ EC No. 440/2008 Method C.7

Deviations:

no

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products:
For the preliminary test, samples were taken at test start (0 h) and test end (120 h).
For the advanced test, samples were taken at test start (0 h) and at a minimum of 7 spaced points for pH 7 and 9, normally between 10 and 90 % of hydrolysis, at each test temperature. The bath temperature was checked automatically once in an hour and at least once per day manually.

Buffers:

Test system
Preliminary test Sterile buffer solutions with pH values 4, 7 and 9 (50 °C).
Advanced test Sterile buffer solution with pH values 7 and 9 (20, 30 and 50 °C) and non sterile buffer solution with pH value 9 (10, 20 and 30 °C).

Buffers were prepared from chemicals with analytical grade or better quality following the composition guidance given in “KÜSTER-THIEL, Rechentafeln für die Chemische Analytik” and the OECD Guideline No. 111, respectively, by direct weighing of the buffer components. Buffers were purged with nitrogen for 5 min and then the pH was checked to a precision of at least 0.1 at the test temperatures. Buffers were sterilised by filtration through 0.2 µm.

Buffer solution pH 4 0.18 g of NaOH and 5.7555 g of mono potassium citrate were dissolved in 500 mL double distilled water.

Buffer solution pH 7
Preliminary test 0.7358 g of NaOH and 4.3012 g of KH2PO4 were dissolved in 500 mL double distilled water.
Advanced test 3.854 g of ammonium acetate were dissolved in 500 mL double distilled water.

Buffer solution pH 9 0.426 g NaOH, 1.8638 g KCl and 1.5458 g H3BO3 were dissolved in 500 mL double distilled water.

Reason for the selection These buffer systems were selected according to the guidelines. The buffer systems were suitable for their pH values.

Details
Chemical Origin Batch number Purity [%]
NaOH VWR 14G150013 ≥99.7
16B290018 ≥99.7
H3BO3 VWR 13J180014 100.1
KCl ROTH 475237252 ≥ 99.5
Ammonium acetate VWR 13D240001 99.8
KH2PO4 VWR 14I050002 99.8
KH2 Citrate FLUKA BCBH3957V ≥ 98
Double distilled water ROTH 335233316 conductivity: ≤ 2.0 μS/cm
415234632 conductivity: ≤ 2.0 μS/cm
086239961 conductivity: ≤ 2.0 μS/cm

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: HPLC vials, volume 1.5 mL
- Measures taken to avoid photolytic effects:Photolytic effects were avoided by using opaque water baths.
- Measures to exclude oxygen: None
- Is there any indication of the test material adsorbing to the walls of the test apparatus? No

TEST MEDIUM
- Volume used/treatment: 0.7 mL
- Preparation of test medium: The test item was dissolved in acetonitrile. 0.693 mL of buffer solutions were spiked with 0.007 mL test item solution at 4000 µg/L in acetonitrile to a test item concentration of 40 µg/L in the test containers. After the vials were sealed they were transferred into the thermostat. The time between test item application and transfer to thermostat as well as analysis of the start valuesdid not exceed 30 min for all test conditions.

- Incubation:
preliminary test: 2016-02-05 to 2016-02-10 (pH 4, 7 and 9; 50°C)
advanced test: 2016-05-23 to 2016-06-22 (pH 7; 20, 30 and 50°C)
2016-05-23 to 2016-06-22 (pH 9; 20 and 30°C)
2016-06-30 to 2016-07-04 (pH 9; 50°C)

- Temperatures:
Preliminary test: 50 ± 0.5 °C
Advanced test: 20, 30 and 50 ± 0.5 °C

- Sterility:
The sterility of the test solutions was checked by colony forming units (CFU)-determination with Water Plate Count Agar if the test duration was > 120 h. The CFU were determined from additional samples at test end by incubation at 36 ± 1 °C for 48 hours and at 22 ± 1 °C for 72 hours.

- Renewal of test solution: None

Duration:

720 h

pH:

7

Temp.:

20 °C

Initial conc. measured:

40.5 µg/L

Duration:

720 h

pH:

7

Temp.:

30 °C

Initial conc. measured:

40.5 µg/L

Duration:

719 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

40.5 µg/L

Duration:

720 h

pH:

9

Temp.:

20 °C

Initial conc. measured:

40.1 µg/L

Duration:

720 h

pH:

9

Temp.:

30 °C

Initial conc. measured:

40.1 µg/L

Duration:

94.2 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

42.1 µg/L

Number of replicates:

One sampling at test start and a minimum of 7 spaced points (actual 7 for pH 7 and 20 °C, 8 for pH 7 30 and 50 °C and pH 9 20 °C as well as 9 for pH 9 and 30 and 50 °C).

Positive controls:

no

Negative controls:

yes

Remarks:

buffer solutions (pH 4, 7 and 9)

Preliminary study:

In the preliminary test more than 10% of the test item degraded after 120 hours at pH 7 and 9.

Degradation [%] at 50 °C after 120 Hours
 
Hydrolysis Time Degradation [%]
[hours] pH 4 pH 7 pH 9
120 0.00 28.1 65.8

Test performance:

CHRONOLOGICAL TEST DESCRIPTION
- Method validation
- Preparation of the test solutions (experimental starting)
- Thermostatisation of the test solutions
- Analysis of samples
- Calculation of reaction rate constants and half-lives for the test item

Transformation products:

no

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

No significant hydrolysis was observed at pH 4 and 7. Therefore the test item was considered as hydrolytically stable under this condition and a half-life of > 1 year could be assumed for environmental typical temperatures.

Key result

pH:

7

Temp.:

20 °C

DT50:

> 1 yr

Remarks on result:

other: For pH 7 no hydrolysis was observed and therefore a half-life of > 1 year could be assumed for environmental typical temperature.

Key result

pH:

9

Temp.:

20 °C

DT50:

> 30 d

Remarks on result:

other: The test item showed a slow hydrolysis rate

Details on results:

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

Hydrolysis Results for Hostavin 3055

Hydrolysis Results forthe Test Itemat pH 7 and 20 °C

Hydrolysis Time [h]	Concentration [µg/L]	Ln Concentration
0.00	40.5	3.70
24.9	40.7	3.71
51.8	43.0	3.76
99.0	39.3	3.67
221	41.3	3.72
266	37.3	3.62
362	41.7	3.73
720	42.9	3.76

Hydrolysis Results forthe Test Itemat pH 7 and 30 °C

Hydrolysis Time [h]	Concentration [µg/L]	Ln Concentration
0.00	40.5	3.70
8.48	40.2	3.69
24.8	41.1	3.72
51.7	38.8	3.66
98.7	39.0	3.66
221	40.3	3.70
266	39.0	3.66
361	42.1	3.74
720	43.1	3.76

Hydrolysis Results forthe Test Itemat pH 7 and 50 °C

Hydrolysis Time [h]	Concentration [µg/L]	Ln Concentration
0.00	40.5	3.70
7.37	40.0	3.69
24.3	38.9	3.66
51.2	35.1	3.56
98.4	37.1	3.61
221	51.6	3.94
265	33.3	3.51
361	43.1	3.76
719	32.7	3.49

Hydrolysis Results forthe Test Itemat pH 9 and 20 °C 

Hydrolysis Time [h]	Concentration [µg/L]	Ln Concentration
0.00	40.1	3.69
23.0	34.3	3.54
27.9	34.2	3.53
29.9	35.0	3.55
49.7	37.5	3.62
74.9	34.6	3.54
264	33.9	3.52
361	28.9	3.37
720	22.7	3.12

 

Hydrolysis Results forthe Test Itemat pH 9 and 30 °C 

Hydrolysis Time [h]	Concentration [µg/L]	Ln Concentration
0.00	40.1	3.69
8.30	33.8	3.52
22.4	27.4	3.31
27.1	22.5	3.12
29.5	28.0	3.33
49.4	30.4	3.41
74.5	25.5	3.24
97.2	24.8	3.21
263	17.4	2.86
720	8.21	2.11

Hydrolysis Results forthe Test Itemat pH 9 and 50 °C

Hydrolysis Time [h]	Concentration [µg/L]	Ln Concentration
0.00	42.1	3.74
0.917	28.7	3.36
2.45	17.6	2.87
3.75	17.2	2.84
4.47	17.4	2.86
5.62	17.1	2.84
7.85	18.1	2.90
24.1	14.6	2.68
26.8	12.8	2.55
94.2	10.2	2.32

 

 Kinetic Considerations

 

For the test conditions at pH 7 theln concentrationvs.timeplots have no regression graphs with slopes significantly non zero. Therefore reaction kinetics could not be applied for data computation.

For the test conditions at pH 9 theln concentrationvs.timeplots have regression graphs with slopes significantly non zero. Therefore first order reaction kinetics was applied for data computation. A confirmation of pseudo first order reaction kinetics with coefficients of determination > 0.8 could be obtained for pH 9 at 20 and 30 °C. For pH 9 at 50 °C the coefficient of determination was < 0.8. Nevertheless, due to the acceptable linearization to higher hydrolysis times, also for this condition a first order reaction kinetics was applied.

 

Reaction Rate Constants and Half-Lives of Hostavin 3055 at pH 9 

	pH 9
	20 °C	30 °C	50 °C
Slope of regression graph	-6.52 · 10^-4	-1.89 · 10^-3	-9.26 · 10^-3
Correlation factor [r^2]	0.886	0.900	0.445
Reaction rate constantkobs[1/s]	1.81 · 10^-7	5.24 · 10^-7	2.57 · 10^-6
Half-lifeT½[h]	1063	367	74.8
Confidence interval of half-lifeT½[h]	840 to 1483	295 to 476	41.6 to 627
Half-lifeT½[d]	44.3	15.3	3.12
Confidence interval of half-lifeT½[d]	35.0 to 61.8	12.3 to 19.8	1.73 to 26.1

 

pH-Value of the Test Systems

measured before start of hydrolysis

Test	Intended pH-value	Measured pH-value at 20 °C	Measured pH-value at 30 °C	Measured pH-value at 50 °C
Preliminary	4.0 ± 0.1	n.a.		4.022
	7.0 ± 0.1			6.993
	9.0 ± 0.1			9.003
Advanced	7.0 ± 0.1	7.035	6.997	7.017
	9.0 ± 0.1	9.049	9.052	8.994

 n.a.: not applicable, only tested at 50 °C in preliminary testing

Temperature of the Test System

measured every hour

Test	pH value	Intended Temperature	Measured Temperature
			Mean ± SD	Min. / Max.
Preliminary	4, 7, 9	50.0 ± 0.5	50.0 ± 0.0	49.9 / 50.0
Advanced	7	20.0 ± 0.5	20.0 ± 0.04	20.0 / 20.2
		30.0 ± 0.5	30.0 ± 0.03	29.9 / 30.0
		50.0 ± 0.5	50.0 ± 0.04	49.9 / 50.1
	9	10.0 ± 0.5	20.0 ± 0.06	20.0 / 20.2
		20.0 ± 0.5	30.0 ± 0.03	29.9 / 30.0
		30.0 ± 0.5	49.9 ± 0.2	49.0 / 50.0^1

              SD = Standard deviation

                   1   = Temperature out of range for 4 hours (4% of total runtime)

              

Validity criteria fulfilled:

yes

Conclusions:

The test item showed a slow hydrolysis rate (t1/2 > 30 d) for pH 9 at 20 °C, and a moderate hydrolysis rate (2.4 h ≤ t1/2 ≤ 30 d) for pH 9 at 30 and 50 °C. For pH 7 no hydrolysis was observed.
At pH 4 no significant reduction of the test item concentration was observed within the preliminary test and therefore the test item was considered as hydrolytically stable under this condition and a half-life > 1 year could be assumed for environmental typical temperatures.

Executive summary:

Hydrolysis as a function of pH was determined according to OECD Guideline No. 111 and Council Regulation (EC) No. 440/2008, Method C.7 for the test item Hostavin3055 (batch number: DEF2101115) from 2016 -02 -05 to 2016 -07 -04 at Noack Laboratorien, Sarstedt, Germany.

 

Analyses of the test item Hostavin3055 were performed via LC-MS/MS on a reversed phase analytical column using the test item as external standard. The analytical method was validated with satisfactory results with regard to linearity, accuracy, precision and specificity.

 

The preliminary test was conducted with a test item concentration of 40 µg/L in buffer solutions at pH 4, 7 and 9 and 50 °C. For the pH‑values pH 7 and 9 the advanced test was performed, as a significant reduction (> 10%) of the test item concentration was observed in the preliminary test. At pH 4 no significant reduction of the test item concentration was observed and therefore the test item was considered as hydrolytically stable under this condition and a half-life of > 1 year could be assumed for environmental typical temperatures.

 

The advanced test was conducted with a test item concentration of 40 µg /Lin buffer solution of pH 7 and 9 at temperatures of 20, 30 and 50 °C, respectively. Samples were taken at test start (0 h) and at 7 to 9 spaced points until test end. Pure test systems were analysed at test start and test end and there was no analytical interference with the test item.

 

Reaction rate constants and half-lives were calculated for pH 9 from the analysed samples based on a first order reaction kinetics model. For pH 7 no calculations could be performed, because the slopes of the regression graphs were not significantly non zero.

 

The test item showed a slow hydrolysis rate (t_1/2> 30 d) for pH 9 at 20 °C, and a moderate hydrolysis rate (2.4 h ≤ t_1/2≤ 30 d) for pH 9 at 30 and 50 °C. For pH 7 no hydrolysis was observed and therefore a half-life of > 1 year could be assumed for environmental typical temperature.

Reaction Rate Constants and Half-Lives at pH9 

	pH 9
	20 °C	30 °C	50 °C	25 °C^1)
Reaction rate constantkobs[1/s]	1.81 · 10^-7	5.24 · 10^-7	2.57 · 10^-6	3.06 · 10^-7
Half-lifeT½[h]	1063	367	74.8	629
Half-lifeT½[d]	44.3	15.3	3.12	26.2
Number of data points	9	10	10	EA= 6.91 · 10^4J * mol^-1
Slope of regression graph	significantly non zero

1)     = values calculated via Arrhenius equation

E_A    = activation energy

Description of key information

The test item showed a slow hydrolysis rate  (t1/2 = 44.3 d) for pH 9 at 20 °C, and a moderate hydrolysis rate  (2.4 h ≤ t1/2 ≤ 30 d) for pH 9 at 30 and 50 °C. For pH 7 no hydrolysis was observed and therefore a half-life of > 1 year could be assumed for environmentally typical temperatures.

At pH 4 no significant reduction of the test item concentration was observed within the preliminary test and therefore the test item was considered as hydrolytically stable under this condition and a half-life > 1 year could be assumed for environmentally typical temperatures.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

20 °C

Additional information

Hydrolysis as a function of pH was determined according to OECD Guideline No. 111 and Council Regulation (EC) No. 440/2008, Method C.7 for the test item from 2016 -02 -05 to 2016 -07 -04 at Noack Laboratorien, Sarstedt, Germany.

 

Analyses of the test item were performed via LC-MS/MS on a reversed phase analytical column using the test item as external standard. The analytical method was validated with satisfactory results with regard to linearity, accuracy, precision and specificity.

 

The preliminary test was conducted with a test item concentration of 40 µg/L in buffer solutions at pH 4, 7 and 9 and 50 °C. For the pH‑values pH 7 and 9 the advanced test was performed, as a significant reduction (> 10%) of the test item concentration was observed in the preliminary test. At pH 4 no significant reduction of the test item concentration was observed and therefore the test item was considered as hydrolytically stable under this condition and a half-life of > 1 year could be assumed for environmental typical temperatures.

 

The advanced test was conducted with a test item concentration of 40 µg /Lin buffer solution of pH 7 and 9 at temperatures of 20, 30 and 50 °C, respectively. Samples were taken at test start (0 h) and at 7 to 9 spaced points until test end. Pure test systems were analysed at test start and test end and there was no analytical interference with the test item.

 

Reaction rate constants and half-lives were calculated for pH 9 from the analysed samples based on a first order reaction kinetics model. For pH 7 no calculations could be performed, because the slopes of the regression graphs were not significantly non zero.

 

The test item showed a slow hydrolysis rate (t1/2> 30 d) for pH 9 at 20 °C, and a moderate hydrolysis rate (2.4 h ≤ t1/2≤ 30 d) for pH 9 at 30 and 50 °C. For pH 7 no hydrolysis was observed and therefore a half-life of > 1 year could be assumed for environmentally typical temperatures.