2-Butenedioic acid (Z)-, ester with 1,2-propanediol, compd. with 2-(dibutylamino)ethanol

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:

other: According to international guideline(s), GLP-compliant, performed in recognized contract research organization, no restrictions, fully adequate for assessment.

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 intervals: 0 and 5 days
- Sampling method: The hydrolysis experiments were carried out in screw cap vials. For the test material three replicates per pH and sampling date were prepared (i.e. 3x3x2 vials). For control samples one replicate per pH and sampling date was prepared (i.e. 1x3x2 vials). The same test conditions and procedure were applied to all test vials.
- Sampling intervals/times for pH measurements: at start and end of the experiment
- Sample storage conditions before analysis: 4-5 hours (time to ship samples from the Test Facility to the Test Site where NMR analysis was performed. Shipment did not have an any impact on the outcome of the hydrolysis)

Buffers:

- pH: 4
- Type and final molarity of buffer: phtalate buffer 0.05 M
- Composition of buffer: 125 ml of 0.2 M Potassium-hydrogen-phtalate and 1 ml of 0.2 M sodium hydroxide solution were diluted to 500 mL with ultrapure water.

- pH: 7
- Type and final molarity of buffer: phosphate buffer, 0.05 M
- Composition of buffer: 125 ml of 0.2 M Potassium-dihydrogen-phosphate and 73.9 ml of 0.2 M sodium hydroxide solution were diluted to 500 mL with ultrapure water.

- pH: 9
- Type and final molarity of buffer: borate buffer, 0.05 M
- Composition of buffer: 53.5 ml of 0.2 M Sodium hydroxide and 125 ml of 0.2 M Boric acid/Potassium chloride solution were diluted to 500 mL with ultrapure water.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: screw cap vials
- Sterilisation method: all glass and plastic labware was autoclaved. Test solutions were filter-sterilised (0.2 µm membrane filter)
- Lighting: dark
- Measures to exclude oxygen: Nitrogen was bubbled into the water for five minutes before the preparation of the solutions.
- If no traps were used, is the test system closed/open: closed
- Is there any indication of the test material adsorbing to the walls of the test apparatus? no

TEST MEDIUM
- Volume used/treatment. Not indicated
- Kind and purity of water: ultrapure water (ASTM Type I)
- Preparation of test medium: The test material was dissolved in the buffer solutions at a concentration of 10 g/L using a ultrasonic bath. Each solution was filtered through a 0.22 µm membrane filter. Nitrogen was bubbled into the solutions.

Number of replicates:

three

Positive controls:

no

Negative controls:

no

Preliminary study:

The degree of degradation in pH 7 and 9 buffers exceeded 10% of the initial concentration. At pH 4, no degradation was observed.

Transformation products:

not measured

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

At pH 7 and 9, several new peaks were detected in the NMR spectra of the incubated samples. Based on normalised integral values the estimated conversion was larger than 10%. Transformation products could not be identified by the analytical method.

Key result

Type:

not specified

Remarks on result:

not determinable because of methodological limitations

Validity criteria fulfilled:

not applicable

Conclusions:

The data gathered in this study are sufficient for the purpose of this screening test (with clearly >10% hydrolysis at pH 7 and 9).
NMR analysis is the only available analytical method which was found to be able to provided quantitative information on the test item content for this complex UVCB material in aqueous media. NMR is a suitable method for relatively few samples, due to the complexity of the methodology and the complex output. Hence it is considered not to be technically feasible to perform a full kinetic evaluation of the degradation process.The NMR analysis is not suitable for this purpose.
Therefore, the TIER 2 and 3 of the abiotic degradation tests are not technically feasible to perform.

Description of key information

dissipation half-life < 1 year at 25°C (OECD 111, EU C.7)

Additional information

At pH 7 and 9, more than 10% degradation was observed after incubation for 5 days at 50°C, while no degradation was observed at pH 4. Although NMR has been applied in this preliminary study, full kinetic evaluation of the degradation process is regarded as technically not feasible due to the lack of a suitable analytical method for this complex test material (UVCB substance).