Hexamethylene diisocyanate, oligomers, reaction products with 3-methoxypropylamine

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

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

Specific details on test material used for the study:

CAS No.: 162492-07-1; Purity: unknown by lhe sponsor, treated as 100% pure; Appearance: white to off-white solid

Radiolabelling:

no

Analytical monitoring:

yes

Details on test conditions:

Preparation of the test solutions:

Test 1
Prior to the start of the test, the test solutions were freshly prepared. Test substance amounts between the 29.8 and 35.9 mg were weighed into 50.0 mL volumetric flasks. The flasks were filled up to the mark with aqueous solutions buffered at pH 4, pH 7 and pH 9, respectively. The test substance did not dissolve completely. The resultant solutions were filter-sterilised through a 0.2 um membrane filter (FP 30/0.2 CA-S) and transferred into sterile glass vessels. To exclude oxygen, nitrogen gas was bubbled through each solution for 5 minutes. Thereafter, each vessel was tightly sealed with a septum-crimp cap.

Test 2
Prior to the start of the test, the test solutions were freshly prepared. Test substance amounts between the 114 and 115 mg were weighed into 100.0 mL volumetric flasks. The solutions were filter-sterilised through a 0.2 um membrane filter. To exclude oxygen, nitrogen gas was bubbled through each solution for 10 minutes. Thereafter, each vessel was tightly sealed with a septum-crimp cap.


Preliminary study

Test 1
The test solutions at pH 4, pH 7 and pH 9 were placed in a thermostatically controlled water bath at 50.0 ± 0.5 °C in the dark. The concentration of the test substance was determined immediately after preparation (t=0), after 2.4 hours and aftar 5 days of incubation. At each sampling point, a 2.5 mL sample was taken for pretreatment and analysis.

Test 2
The test solutions at pH 4, pH 7 and pH 9 were placed in a thermostatically controlled water bath at 50.0 ± 0.5 °C in the dark. The concentration of the test substance was determined immediately after preparation (t=0) and after 2.4 hours and after 5 days of incubation. At each sampling point, four vessels were taken for pretreatment and analysis.

For each test solution, the pH value of each sample was measured at room temperature.

Preliminary study:

Test 1:
Based on the structure of the test substance, stability was expected. In order to find out whether the results from the preliminary test indicate instability were correct, it was decided to repeat the test using a different vessel for each sampling point.

Transformation products:

no

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

The hydrolysis test 2 was performed at 50.0 ± 0.5°C. No test substance was measured in the blank buffer solutions for pH 9. In the chromatograms of samples from the blank buffer solutions for pH 4 and pH 7 small peaks were observed at the retention lime of the test substance. Contribution to peak areas samples was <11 % and therefore considered negligible. The measured values show a big spread due to the low concentrations measured. Improvement of the analytical method (i.e. increasing sensitivity and accuracy) is considered not possible. Because concentrations cannot be measured sufficiently accurate, it is not possible to determine the half-Iife time at 25°C. Nevertheless, it is expected based on the structural formula that the test substance is hydrolytically stable (half-life time at 25°C> 1 year) in aqueous solutions buffered at pH 4, pH 7 and pH 9.

Key result

pH:

4

Temp.:

25 °C

Remarks on result:

not determinable

Remarks:

based on structural formula the test substance is expected to be hydrolytically stable (half-life: >1yr at 25 °C)

Key result

pH:

7

Temp.:

25 °C

Remarks on result:

not determinable

Remarks:

based on structural formula the test substance is expected to be hydrolytically stable (half-life: >1yr at 25 °C)

Key result

pH:

9

Remarks on result:

not determinable

Remarks:

based on structural formula the test substance is expected to be hydrolytically stable (half-life: >1yr at 25 °C)

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, the half-life time at 25°C could not be determined. Nevertheless, it is expected based on the structural formula that the test substance is hydrolytically stable (half-life at 25°C > 1 year) in aqueous solutions buffered at pH 4, pH 7 and pH 9.

Executive summary:

A study was conducted to determine the hydrolysis behavior of the test substance at pH values normally found in the environment (pH 4- 9) according to EU Method C.7, in compliance with GLP. Two preliminary tests were performed. Analyses were based on the major constituents of the substance but concentrations in the test solutions could not be measured accurately due to the low levels. Under the study conditions, the half-life time at 25°C could not be determined. Nevertheless, it is expected based on the structural formula that the test substance is hydrolytically stable (half-life at 25°C > 1 year) in aqueous solutions buffered at pH 4, pH 7 and pH 9 (Brekelmans, 2003).

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

A study was conducted to determine the hydrolysis behavior of the test substance at pH values normally found in the environment (pH 4- 9) according to EU Method C.7, in compliance with GLP. Two preliminary tests were performed. Analyses were based on the major constituents of the substance but concentrations in the test solutions could not be measured accurately due to the low levels. Under the study conditions, the half-life time at 25°C could not be determined. Nevertheless, it is expected based on the structural formula that the test substance is hydrolytically stable (half-life at 25°C > 1 year) in aqueous solutions buffered at pH 4, pH 7 and pH 9 (Brekelmans, 2003).