Reaction products of 3-aminomethyl-3,5,5-trimethylcyclohexylamine with 2,2'-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 2008-07-15 to 2008-08-29

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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:

Analysis of Samples
The samples were tenfold diluted with the dilution mixture and the content of the test item was determined by the reverse phase HPLC method.

Buffers:

Buffer solution:
Compositions of the buffer solution: pH 9.0: 107 mL 0.2 M Sodium hydroxide and 250 mL 0.2 M Boric acid and Potassium chloride was diluted to 1000 mL with ultra-pure water. The sterile buffer solution was prepared using reagent grade chemicals and ultra-pure, sterile water. The needed amount was prepared according to the above ratios. The pH of the buffer solution was checked with a calibrated pH meter.

Details on test conditions:

Preliminary Test
In the course of the preliminary test (Study Code: 07/523-336AN) the test item proved to be hydrolytically unstable at pH 9. Concentration was decreased by about 21 % after 5 days at 50 °C. Thus, main test was performed at pH 9 only.
Main Test
Test 1: The hydrolysis was examined at pH 9 at 50 °C ± 0.5 °C. The test was carried out in triplicate. The Test 1 was started on 17 July 2008. Based on the results of the Test 1, the reaction is considered to be pseudo-first order, therefore, the study was continued with Test 3.
Test 3: The hydrolysis was examined at pH 9 at two temperatures above 50 °C differing from each other by at least 10 °C (55 °C ± 0.5 °C and 67 °C ± 0.5 °C). The reaction solution was analysed at the start of the test and at least three other time points when the degree of hydrolysis was greater than 30 % (for each temperature). The test was carried out in duplicate. Test 3 was started on 13 August 2008.
Test Solutions
Test solutions were prepared by the dilution of the saturated stock solutions. The stock solutions were diluted with the respective buffer solution. The test item concentration in the buffer solutions: Test 1: in the buffer solution pH 9 131 mg/L (0.19 mM), Test 3: in the buffer solution pH 9 119 mg/L (0.17 mM), 2000 mL sterile solution was prepared. Solution was transferred into ~25 mL stoppered tubes. Additionally, control buffer samples were stored at each temperature. The solution was analysed at the start of the tests and then at appropriate time intervals: Test 1: in order to get at least six other data points in the range of 20 to 70 % hydrolysis. Test 3: at least two other data points when the degree of hydrolysis is greater than 30 %.


The hydrolysis was examined at pH value 9.0 in the dark. Temperature: 50 °C ± 0.5 °C, 55 °C ± 0.5 °C, 67 °C ± 0.5 °C.
Light and oxygen: The hydrolysis reaction was carried out using a dark thermostat to avoid photolytic effects. Nitrogen was bubbled into the water for five minutes before the preparation of the solutions in order to exclude oxygen. All glassware, water and buffer solution were sterilised.

Duration:

6 d

pH:

9

Temp.:

50

Initial conc. measured:

101 mg/L

Duration:

8 d

pH:

9

Temp.:

50

Initial conc. measured:

98 mg/L

Duration:

14 d

pH:

9

Temp.:

50

Initial conc. measured:

83 mg/L

Duration:

15 d

pH:

9

Temp.:

50

Initial conc. measured:

78 mg/L

Duration:

19 d

pH:

9

Temp.:

50

Initial conc. measured:

66 mg/L

Duration:

25 d

pH:

9

Temp.:

50

Initial conc. measured:

50 mg/L

Duration:

144 h

pH:

9

Temp.:

55

Initial conc. measured:

87 mg/L

Duration:

186 h

pH:

9

Temp.:

55

Initial conc. measured:

80 mg/L

Duration:

210 h

pH:

9

Temp.:

55

Initial conc. measured:

66 mg/L

Duration:

356 h

pH:

9

Temp.:

55

Initial conc. measured:

41 mg/L

Number of replicates:

Three replicates.

Positive controls:

no

Negative controls:

yes

Remarks:

control buffer

Statistical methods:

Calculations were carried out using “EXCEL for Windows". The calibration curves were constructed with “STATISTICA for Windows" using weighted linear regression. The factor was 1/concentration.

Preliminary study:

In the course of the preliminary test (Study Code: 07/523-336AN) the test item proved to be hydrolytically unstable at pH 9. Concentration was decreased by about 21 % after 5 days at 50 °C.

Transformation products:

not measured

% Recovery:

78

St. dev.:

101

pH:

9

Temp.:

50 °C

Duration:

6 d

% Recovery:

77

St. dev.:

98

pH:

9

Temp.:

50 °C

Duration:

8 d

% Recovery:

65

St. dev.:

83

pH:

9

Temp.:

50 °C

Duration:

14 d

% Recovery:

61

St. dev.:

78

pH:

9

Temp.:

50 °C

Duration:

15 d

% Recovery:

52

St. dev.:

66

pH:

9

Temp.:

50 °C

Duration:

19 d

% Recovery:

39

St. dev.:

50

pH:

9

Temp.:

50 °C

Duration:

25 d

% Recovery:

73

St. dev.:

87

pH:

9

Temp.:

55 °C

Duration:

144 h

% Recovery:

68

St. dev.:

80

pH:

9

Temp.:

55 °C

Duration:

186 d

% Recovery:

55

St. dev.:

66

pH:

9

Temp.:

55 °C

Duration:

210 d

% Recovery:

35

St. dev.:

41

pH:

9

Temp.:

55 °C

Duration:

356 h

Key result

pH:

9

Temp.:

50 °C

Hydrolysis rate constant:

0.04 h-1

DT50:

19 d

Type:

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

pH:

9

Temp.:

55 °C

Hydrolysis rate constant:

0 h-1

DT50:

10 d

Type:

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

pH:

9

Temp.:

67 °C

Hydrolysis rate constant:

0.01 h-1

DT50:

5 d

Type:

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

Key result

pH:

9

Temp.:

25 °C

Hydrolysis rate constant:

0 h-1

DT50:

140 d

Type:

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

Remarks on result:

other: Arrhenius equation

Total recovery rate of test substance in (%)

Recovery %	St.dev.	pH	Temp.	Duration
60	71 ± 5	9	67	114 hours
49	59 ± 5	9	67	136 hours
45	53 ± 5	9	67	144 hours
33	39 ± 2	9	67	186 hours
36	44 ± 5	9	67	210 hours
19	22 ± 9	9	67	282 hours

Validity criteria fulfilled:

yes

Conclusions:

The following half-lives of the test item were determined:
t 1/2 at 25 °C and pH 9: 140 days
t 1/2 at 50 °C and pH 9: 19 days

Executive summary:

The purpose of this study was to evaluate the hydrolysis of the test item at pH value of 9 according to EU Method C.7.

The calculated half lives of the hydrolysis reactions at pH 9 are given in the following table:

Buffer solution	Temperature	t 1/2
pH 9	25 °C	140 days (3349 hours)
pH 9	50 °C	19 days (450 hours)

Description of key information

The purpose of this study was to evaluate the hydrolysis of the test item at pH value of 9. The calculated half-lives of the hydrolysis reactions are 140 days (3349 hours) at temperature 25 °C and 19 days (450 hours) at temperature 50 °C.

Key value for chemical safety assessment

Half-life for hydrolysis:

3 349 h

at the temperature of:

298.2 K

Additional information

The hydrolysis was examined at pH value 9.0 in the dark at different temperatures of 50 °C (± 0.5), 55 °C (± 0.5) and 67 °C (± 0.5). The hydrolysis reaction was carried out using a dark thermostat to avoid photolytic effects. Nitrogen was bubbled into the water for five minutes before the preparation of the solution in order to exclude oxygen. The calculated half lives of the hydrolysis reactions are 140 days (3349 hours) at temperature 25 °C and 19 days (450 hours) at temperature 50 °C.