A mixture of: 7,9,9-trimethyl-3,14-dioxa-4,13-dioxo-5,12-diazahexadecane-1,16-diylprop-2-enoate; 7,7,9-trimethyl-3,14-dioxa-4,13-dioxo-5,12-diazahexadecan-1,16-diylprop-2-enoate

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July 2008

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

not specified

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling method: not stated
- The sampling time was adapted to the half-life curve. The minimum sampling time is 5 minutes.

Buffers:

- pH (25°c) = 4.01 ± 0.01 ; MERCK, CertiPUR® 1.09406.1000(Potassium hydrogen phthalate)
- pH (25°c) = 7.00 ± 0.01 ; MERCK, CertiPUR® 1.09407.1000(Potassium di hydrogen phosphate/di-sodium hydrogen phosphate)
- pH (25°c) = 9.00 ± 0.01 ; MERCK, CertiPUR® 1.09407.1000(boric acid/potassium Chloride/sodium hydroxide)
- Demineralized water (MilliQ)

Details on test conditions:

• Ultra fast HPLC conditions
Column: VisionHT C18B, 1.5 µm; length: 100 mm ; ID: 2 mm
Flow: 300 µl/min
Injection volume: 0.2 µl
Column Oven: 60°c
Gradient used: (total run 3.5 min)
Time (min) H2O (%) ACN (%) Ammonium Acetate
(25mM)
0.00 65 30 5
0.25 65 30 5
0.50 45 50 5
0.65 45 50 5
1.15 30 65 5
1.85 30 65 5
2.00 20 75 5
2.20 20 75 5

• Mass Spectrometry conditions
Probe: Heated Electrospray in positive ion mode
Tune Method: on test substance-HESI
Full scan: ITMS + c norm o(160.0-800.0 uma)

Number of replicates:

1 solution of each temperature and pH

Transformation products:

yes

No.:

#1

No.:

#2

No.:

#3

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

- Hydrolysis of the test substance at pH 9 leads to the formation of three hydrolysis products:
(i) acrylic acid (MW = 72 g/mol; C3H4O2)
(ii) hydrolysis product 1 (MW = 388 g/mol; C18H32N2O7)
(iii) hydrolysis product 2 (MW = 334 g/mol; C15H30N2O6)

Key result

pH:

7

Temp.:

25 °C

DT50:

1.35 d

- Recovery: not tested

- Results of preliminary test: for 5 days at pH 4, 7, 9 at 50°

	pH 4	pH 7	pH 9
Interim Assessment: IS10% of the test substance hydrolyzed in 5 days (t0.5>1y at 25°C)	Yes No hydrolysis detected	Yes Small hydrolysis detected IS 10%	No Hydrolysis detected IS > 10%

Results of arrhenius equation for hydrolysis of the test substance (-THMDI-) at pH 9.

T	k	Stdev	Half-life
°Celsius	[day]-1	%	days	hours
20	0.282		2.46	59.1
21	0.318		2.18	52.3
22	0.359		1.93	46.3
23	0.405		1.71	41.0
24	0.457		1.52	36.4
25	0.515		1.35	32.3
28	0.732	1.0	0.95	22.7
35	1.620	1.5	0.43	10.3
50	7.915	0.5	0.09	2.1

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, there was no or less than 10% hydrolysis of the test substance, respectively, at pH 4 and 7. Hydrolysis of the test substance at pH 9 led to the formation of three hydrolysis products: acrylic acid, hydrolysis product 1 (MW = 388 g/mol; C18H32N2O7) and hydrolysis product 2 (MW = 334 g/mol; C15H30N2O6).

Executive summary:

A study was conducted to determine the hydrolysis of the test substance according to OECD Guideline 111. Under the study conditions, there was no or less than 10% hydrolysis of the test substance, respectively, at pH 4 and 7. Hydrolysis of the test substance at pH 9 led to the formation of three hydrolysis products: acrylic acid, hydrolysis product 1 (MW = 388 g/mol; C18H32N2O7) and hydrolysis product 2 (MW = 334 g/mol; C15H30N2O6) (Boutreau, 2008).

Reference 2

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From June 26, 2008 to August 19, 2008

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 - at 0, 2, 4 and 120 hours

Buffers:

Acetate buffer pH 4: solution of 16.6% 0.05 M sodium acetate and 83.4% 0.05 M acetic acid.

Phosphate buffer pH 7: solution of 0.05 M potassium dihydrogenphosphate adjusted to pH 7 using 1 N sodium hydroxide.

Borate buffer pH 9: solution of 0.05 M boric acid and 0.05 M potassium chloride adjusted to pH 9 using 1 N sodium hydroxide.

Details on test conditions:

Preliminary test
Test substance solutions were prepared in the buffer solutions at a nominal concentration of approximately 85 mg/l. The solutions were filter-sterilised through a 0.2 µm membrane filter and transferred into sterile glass vessels. To exclude oxygen, nitrogen gas was purged through the solutions for 5 minutes. Each vessel was sealed and placed in a thermostatically controlled water bath at 50.1°C +/- 0.1°C.
The concentration of the test substance in the test samples was determined immediately after preparation (t=0), after 2.4 hours and after 5 days. The samples taken at t > 0 were cooled to room temperature using running tap water. The samples were diluted in a 1:1 (v:v) ratio with acetonitrile and analysed.
Blank buffer solutions were treated similarly as the test samples and analysed at t=120.
The pH of each of the test solutions (except for the blanks) was determined at each sampling time.

Stock solutions
Stock solutions of the test substance were prepared in acetonitrile at concentrations in the range 203 - 448 mg/l.

Calibration solutions
During the preliminary test, calibration solutions in the concentration range 0.0400 – 12.0 mg/l were prepared from two stock solutions. The end solution of the calibration solutions was 50/50 (v/v) acetonitrile/water.

Calibration solutions were injected in duplicate. Test samples were analysed by single injection.

Calibration curves were constructed using four concentrations.

Duration:

5 d

Temp.:

25 °C

Number of replicates:

Test samples were analysed by single injection.
Calibration solutions were injected in duplicate.

Negative controls:

yes

Remarks:

Blank buffers

Statistical methods:

not applicable

Preliminary study:

At pH 4, a decrease in concentration < 10% was observed after 5 days. It demonstrates that the half-life time of the test substance at 25°C > 1 year. According to the guideline, no further tests were required.

At pH 7 and pH 9, a decrease in concentration < 50% after 2.4 hours and > 10% after 5 days was observed. According to the guideline, a main test was required to determine the half-life time of the test substance.

The solubility of the test substance in the buffer solutions is much lower than the water solubility (224 mg/l). The analysed concentration at pH 7 and pH 9 is very low and close to the LOQ of the method (0.1 mg/l), therefore it is not possible to perform an accurate main test.

Transformation products:

not measured

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

- Formation and decline of each transformation product during test: not determined

Key result

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Key result

pH:

7

Temp.:

25 °C

Remarks on result:

other: could not be determined

Key result

pH:

9

Temp.:

25 °C

Remarks on result:

other: could not be determined

Details on results:

At pH 7 and 9, the observed water solubility is very close to the limit of quatification (LOQ, 0.1 mg/l) of the analytical method. During the hydrolysis study the aim is to accurately measure concentrations of the test substance down to at least 10% of the starting concentration. This is not possible at pH 7 and 9. The observed decrease in concentration is most likely due to adsorption of test substance to the sample container and not due to hydrolysis. In conclusion, the hydrolysis of test substance at pH 7 and 9 cannot be determined.

At pH 4, a decrease in concentration < 10% was observed after 5 days. This demonstrates that the half-life time of the test substance at 25°C > 1 year. According to the guideline, no further tests were required.

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, the half-life time of the test substance at 25°C and pH 4 is > 1 year, at pH 7: t½ could not be determined and at pH 9: t½ could not be determined.

Executive summary:

The study was conducted to determine the hydrolysis of the test substance according to OECD Guideline 111 and EU Method C.7. Under the study conditions, the half-life at 25°C and pH 4 was > 1 year, at pH 7: t½ could not be determined and at pH 9: t½ could not be determined (Baltussen, 2008).

Key value for chemical safety assessment

Half-life for hydrolysis:

32.3 h

at the temperature of:

25 °C

Additional information

Study 1:

A study was conducted to determine the hydrolysis of the test substance according to OECD Guideline 111. Under the study conditions, there was no or less than 10% hydrolysis of the test substance, respectively, at pH 4 and 7. Hydrolysis of the test substance at pH 9 led to the formation of three hydrolysis products: acrylic acid, hydrolysis product 1 (MW = 388 g/mol; C18H32N2O7) and hydrolysis product 2 (MW = 334 g/mol; C15H30N2O6)

Study 2:

A study was conducted to determine the hydrolysis of the test substance according to OECD Guideline 111 and EU Method C.7. Under the study conditions, the half-life at 25°C and pH 4 was > 1 year, at pH 7: t½ could not be determined and at pH 9: t½ could not be determined (Baltussen, 2008).