Reaction products of m-phenylenebis(methylamine) 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 2008-07-14 to 2008-08-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP and guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Deviations:

no

Remarks:

Deviation Concerning: Result Evaluation (Data Handling) According to the Study Plan: kobs = -slope * 2.303 t1/2 = 0.693/kobs Deviation: kobs = –slope (eq. 3) t1/2 = ln2/kobs (ln2=0.693)

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Buffers:

Compositions of the buffer solutions:
pH 4.0: 2 mL 0.2 M Sodium hydroxide and 250 mL 0.2 M Potassium hydrogen phthalate was diluted to 1000 mL with ultra-pure water
pH 9.0: 107.0 mL 0.2 M Sodium hydroxide and 250 mL 0.2 M Boric acid and Potassium chloride were diluted to 1000 mL with ultra-pure water
These sterile buffer solutions were 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 solutions was checked with a calibrated pH meter.

Details on test conditions:

The hydrolysis was examined at the two different pH values 4.0 and 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:

2 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

105 mg/L

Duration:

4 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

95 mg/L

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

95 mg/L

Duration:

6 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

89 mg/L

Duration:

9 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

73 mg/L

Duration:

12 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

59 mg/L

Duration:

15 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

53 mg/L

Duration:

19 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

44 mg/L

Duration:

1 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

113 mg/L

Duration:

2 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

93 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, the test item proved to be hydrolytically unstable at pH 4 and pH 9. Concentration was decreased by about 48 % after 5 days at 50 °C. Thus main test was performed at pH 4 and pH 9 only.

Transformation products:

not measured

% Recovery:

85

St. dev.:

4

pH:

4

Temp.:

50 °C

Duration:

2 d

% Recovery:

76

St. dev.:

7

pH:

4

Temp.:

50 °C

Duration:

4 d

% Recovery:

76

St. dev.:

8

pH:

4

Temp.:

50 °C

Duration:

5 d

% Recovery:

71

St. dev.:

4

pH:

4

Temp.:

50 °C

Duration:

6 d

% Recovery:

51

St. dev.:

3

pH:

4

Temp.:

50 °C

Duration:

9 d

% Recovery:

47

St. dev.:

3

pH:

4

Temp.:

50 °C

Duration:

12 d

% Recovery:

43

St. dev.:

8

pH:

4

Temp.:

50 °C

Duration:

15 d

% Recovery:

36

St. dev.:

1

pH:

4

Temp.:

50 °C

Duration:

19 d

% Recovery:

75

St. dev.:

22

pH:

9

Temp.:

50 °C

Duration:

2 d

% Recovery:

72

St. dev.:

24

pH:

9

Temp.:

50 °C

Duration:

4 d

Key result

pH:

4

Temp.:

25 °C

DT50:

236 d

Type:

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

Key result

pH:

9

Temp.:

25 °C

DT50:

54 d

Type:

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

Key result

pH:

4

Temp.:

50 °C

Hydrolysis rate constant:

0.06 d-1

DT50:

13 d

Type:

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

Key result

pH:

9

Temp.:

50 °C

Hydrolysis rate constant:

0.14 d-1

DT50:

5 d

Type:

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

pH:

4

Temp.:

55 °C

Hydrolysis rate constant:

0 h-1

DT50:

137 h

Type:

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

pH:

9

Temp.:

55 °C

Hydrolysis rate constant:

0.02 h-1

DT50:

48 h

Type:

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

pH:

4

Temp.:

67 °C

Hydrolysis rate constant:

0.02 h-1

DT50:

47 h

Type:

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

pH:

9

Temp.:

67 °C

Hydrolysis rate constant:

0.03 h-1

DT50:

24 h

Type:

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

Measured data at a temperature of 50 °C at pH 9

Recovery, %	St.dev.	pH	Temp.	Duration, days
55	1	9	50	5
45	3	9	50	6
39	2	9	50	7
33	1	9	50	8

Measured data at a temperature of 55 °C at pH 4

Recovery, %	St.dev.	pH	Temp.	Duration, hours
64	1	4	55	70
52	1	4	55	114
46	1	4	55	144
39	1	4	55	186

Measured data at a temperature of 67 °C at pH 4

Recovery, %	St.dev.	pH	Tem.	Duration, hours
63	2	4	67	40
38	1	4	67	68
34	1	4	67	74

Measured data at a temperature of 55 °C at pH 9

Recovery, %	St.dev.	pH	Tem.	Duration, hours
61	4	9	55	40
41	1	9	55	64
35	2	9	55	72

Measured data at a temperature of 67 °C at pH 9

Recovery, %	St. dev.	pH	Temp.	Duration, hours
67	2	9	67	20
50	3	9	67	30
36	5	9	67	40
25	1	9	67	46

Rate constants and half-lives calculated at 25°C

Temperature, °C	pH	kobs	t 1/2
25	4	0.0001	5659 hours (236 days)
25	9	0.0005	1299 (54 days)

Validity criteria fulfilled:

yes

Conclusions:

The following half-lives of the test item were determined:
t 1/2 at 25 °C and pH 4: 236 days
t 1/2 at 50 °C and pH 4: 13 days
t 1/2 at 25 °C and pH 9: 54 days
t 1/2 at 50 °C and pH 9: 5 days

Executive summary:

The purpose of this study was to evaluate the hydrolysis of the test item at pH values of 4 and 9.

The calculated half lives of the test item hydrolysis reactions at pH 4 and pH 9 are given in the following table:

Buffer solution	Temperature	t 1/2
pH 4	25 °C	236 days
pH 4	50 °C	13 days
pH 9	25 °C	54 days
pH 9	50 °C	5 days

Description of key information

The purpose of this study was to evaluate the hydrolysis of the test item at pH values of 4 and 9. The calculated half-lives of the hydrolysis are, 236 days (5659 hours) at temperature 25 °C and pH 4.0, 13 days (305 hours) at temperature 50 °C and pH 4.0. 54 days (1299 hours) at temperature 25 °C and pH 9.0 and 5 days (122 hours) at temperature 50 °C and pH 9.0.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 299 h

at the temperature of:

25 °C

Additional information

The hydrolysis was examined at the two different pH values 4.0 and 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 solutions in order to exclude oxygen. The calculated half-lives of the hydrolysis are, 236 days (5659 hours) at temperature 25 °C and pH 4.0, 13 days (305 hours) at temperature 50 °C and pH 4.0. 54 days (1299 hours) at temperature 25 °C and pH 9.0 and 5 days (122 hours) at temperature 50 °C and pH 9.0.