Oxazolidine, 3-butyl-2-(1-ethylpentyl)-

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 2005-04-07 to 2005-04-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted 31.07.1992

Deviations:

yes

Remarks:

A modified version of Method C7 was performed, as the test material degraded almost instantly in aqueous media.

Principles of method if other than guideline:

A modified version of Method C7 was performed, as the test material degraded almost instantly in aqueous media. The test was designed to illustrate the instability of the test material, whilst utilising a test temperature at which the rate of reaction was slow enough to observe some test material in the initial samples.

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

An aliquot (200 mL) of each sample was extracted with three portions (2 x 25 mL) of dichloromethane, each extract being filtered through anhydrous sodium sulphate. The combined extracts were evaporated to dryness and the residue re-dissolved in methanol (2 mL). This was performed in duplicate for each time-point taken.
Aliquots of the sample solutions were taken initially and after 4 hours, and the pH of each solution recorded.

Buffers:

Buffer solutions
- pH: 4
- Composition and molarity: Potassium hydrogen phthalate, 12.5 mmol

- pH: 7
- Composition and molarity: Disodium hydrogen orthophosphate (anhydrous) 7.5 mmol; Potassium dihydrogen orthophosphate 5.0 mmol; Sodium chloride 5.0 mmol

- pH: 9
- Composition and molarity: Disodium tetraborate 2.5; Sodium chloride 5.0 mmol

Details on test conditions:

Preparation of the buffer solutions
The buffer solutions were filtered through a 0.2 µm membrane filters to ensure they were sterile before commencement of the test. Also these solutions were subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen content.

Preparation of samples
Sample solutions were prepared at a nominal concentration of 20 mg/L in the three buffer solutions and split into separate glass flasks for each time-point. A 1 % co-solvent of acetonitrile was used to aid solubility. A nitrogen headspace was used to prevent volatilisation.
The solutions were shielded from light whilst maintained at the test temperature.

Test 1
Sample solutions at pH 4, 7 and 9 were maintained at 10.0 ± 0.5 °C for a period of 4 hours.

Analysis of sample solutions
Aliquots of the sample solutions were taken initially and after 4 hours, and the pH of each solution recorded. The concentration of the sample solution was determined by gas chromatography.

Number of replicates:

2 (duplicates)

Transformation products:

no

% Recovery:

8.89

pH:

4

Temp.:

10 °C

Duration:

0 h

% Recovery:

< 1.17

pH:

4

Temp.:

10 °C

Duration:

4 h

% Recovery:

3.14

pH:

7

Temp.:

10 °C

Duration:

0 h

% Recovery:

< 0.71

pH:

7

Temp.:

10 °C

Duration:

4 h

% Recovery:

1.84

pH:

9

Temp.:

10 °C

Duration:

0 h

% Recovery:

0.978

pH:

9

Temp.:

10 °C

Duration:

4 h

Key result

pH:

4

Temp.:

10 °C

DT50:

< 4 h

Type:

not specified

Key result

pH:

7

Temp.:

10 °C

DT50:

< 4 h

Type:

not specified

Key result

pH:

9

Temp.:

10 °C

DT50:

< 4 h

Type:

not specified

Validity criteria fulfilled:

yes

Conclusions:

The test material was shown to hydrolyse on contact with aqueous media. The respective half-lives of the test item in the prepared buffer solutions (pH 4, pH 7, pH 9) at 10°C were below 4 hours.

Executive summary:

An assessment of the hydrolytic stability of the test material was performed in accordance with EU method C.7. The test item was prepared at a nominal concentration of 20 mg/L in three buffer solutions with varying pH values (pH 4, pH 7 and pH 9). The solutions were maintained at 10 °C for a period of 4 hours. To determine the hydrolytic stability, aliquots of the sample solutions were taken initially and after 4 hours and the residual concentration of the test item was determined by gas chromatography.

The following results were obtained:

- At a pH of 4 less than 1.17 % of the test material was remaining after 4 hours.

- At a pH of 7 less than 0.710 % of the test material was remaining after 4 hours.

- At a pH of 9 less than 0.978 % of the test material was remaining after 4 hours.

In conclusion, all the respective half-lives of the test item in the prepared buffer solutions were below 4 hours. Therefore, the test material was shown to hydrolyse on contact with aqueous media.

Description of key information

The test material was shown to hydrolyse on contact with aqueous media. The respective half-lives of the test item in the prepared buffer solutions (pH 4, pH 7, pH 9) at 10 °C were below 4 hours.

Key value for chemical safety assessment

Half-life for hydrolysis:

4 h

at the temperature of:

10 °C

Additional information

An assessment of the hydrolytic stability of the test material was performed in accordance with EU method C.7. The test item was prepared at a nominal concentration of 20 mg/L in three buffer solutions with varying pH values (pH 4, pH 7 and pH 9). The solutions were maintained at 10 °C for a period of 4 hours. To determine the hydrolytic stability, aliquots of the sample solutions were taken initially and after 4 hours and the residual concentration of the test item was determined by gas chromatography.

The following results were obtained:

- At a pH of 4 less than 1.17 % of the test material was remaining after 4 hours.

- At a pH of 7 less than 0.71 % of the test material was remaining after 4 hours.

- At a pH of 9 less than 0.978 % of the test material was remaining after 4 hours.

In conclusion, all the respective half-lives of the test item in the prepared buffer solution were below 4 hours. Therefore, the test material was shown to hydrolyse on contact with aqueous media.

The key value for the chemical safety assessment was set at a hydrolysis half-life of 4 h in order to obtain a numerical figure to allow for CSA calculations. However, it must be highlighted that this value is based on a very worst case scenario and does not truly reflect the results obtained from this study where the actual half-life determined was considerably less than 4 h.