Ditolyl ether

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014

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

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling time were on day 2014.04.29 and 2014.05.05
- The pH-value of the hydrolysis solution and the temperature during the test were measured and also checked at each test point.
- The calibration was verified at the level of 800 mg/L and 1000 mg/L by using a control calibration solution.
- At each test point the hydrolysis solution was cooled down to room temperature.

Buffers:

- Buffer pH 4 (Fa. Fluka, Citric acid/NaOH/NaCl, Art-Nr.: 33643)
- Buffer pH 7 (Fa. Fluka, KH2PO4/Na2HPO4, Art-Nr.: 33646)
- Buffer pH 9 (Fa. Fluka, Na2B4O7/HCl, Art-Nr.: 33648)

Details on test conditions:

PRE-TEST FOR HYDROLYSIS:
- The test item was applied as an aqueous solution (including 1 % acetonitrile) with a concentration of approx. 1.125 mg/l (0.0000057 mol/l) which fulfills the requirements of OECD TG 111.
- No further solubility test with organic solvent additives > 1% v/v was performed.

PREPARATION OF THE TEST SOLUTIONS:
- For each pH separate stock solutions were prepared by direct application of the test item to the corresponding buffer systems in 200 ml flasks.
- 11.4 mg of the test item Ditolylether were dissolved in 100 ml acetonitrile. This stock solution was 1:100 diluted with buffer solution, leading to a test item concentration of 1.125 mg/l.
- Aliquots of the stock solution were taken to obtain individual vials for every test point. Preparation was carried out under nitrogen as flushing gas, to avoid oxygen.
- The vials were closed and incubated at 50 °C in a heat regulator under dark to avoid any photolytic effects.
- The pH of the blank buffer solution was checked at the beginning of the test.
- The calibration was verified at the level of 800 mg/l and 1000 mg/l by using a control calibration solution.
- Sodium sulfate, potassium hydroxide and an aliquot of the internal standard solution were added to the beaded rim bottles with the sample solution and extracted with 2 ml diethyl ether.
- The organic extract was dried with sodium sulfate and was directly led to the chromatographic measurement.
- The area correction factor of the test item Ditolylether (as sum of isomers) was obtained by calibration measurements using cyclododecane as internal standard.

STERILITY TEST:
- A plate count test was performed at the end of the tests.

Duration:

6 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

1.048 mg/L

Duration:

6 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

1.07 mg/L

Duration:

6 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

1.055 mg/L

Number of replicates:

4 after 6 days of incubation
2 after 0 days of incubation

Preliminary study:

A preliminary study was conducted for 6 days at 50 °C at pH 4, 7 and 9. Ditolylether was found to be stable at 50 °C and, thus, as well as at 25 °C. no half-life times and hydrolysis rates were calculated.

Transformation products:

no

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

If any hydrolysis would occur, cresols are expected as hydrolysis products due to ether cleavage under acidic conditions. Therefore samples at pH 4 were analyzed with the GC twister method to detect cresols. p-Cresol was calibrated as representative substance for the cresols. No cresols were detected.

% Recovery:

93.1

pH:

4

Temp.:

50 °C

Duration:

1 d

% Recovery:

83.6

pH:

4

Temp.:

50 °C

Duration:

6 d

% Recovery:

95.1

pH:

7

Temp.:

50 °C

Duration:

1 d

% Recovery:

82.2

pH:

7

Temp.:

50 °C

Duration:

6 d

% Recovery:

93.4

pH:

9

Temp.:

50 °C

Duration:

1 d

% Recovery:

84.4

pH:

9

Temp.:

50 °C

Duration:

6 d

pH:

4

Temp.:

25 °C

Remarks on result:

hydrolytically stable based on preliminary test

pH:

7

Temp.:

25 °C

Remarks on result:

hydrolytically stable based on preliminary test

pH:

9

Temp.:

25 °C

Remarks on result:

hydrolytically stable based on preliminary test

Details on results:

Ditolylether is assumed to be stable at 50 °C and, thus, as well as at 25 °C, no half-life times and hydrolysis rates were calculated.

The recovery of the test substance was slightly below the criterion of 90 % at pH 7 which would in general be interpreted as hydrolytic degradation. However, if any, hydrolytic degradation would be expected at pH 4 as ether cleavage only occurs under acidic conditions. Cresols would be the hydrolysis products expected at pH 4 but could not be detected using the GC twister method (p-cresol was calibrated as representative substance for the cresols). Thus, it is even more unlikely that abiotic degradation took place at pH 7.

Validity criteria fulfilled:

yes

Remarks:

Recoveries of the test item are in the range from 98.5 % to 101.8 % indicating a satisfying repeatability; the analytical method was sufficiently sensitive to quantify test item concentrations down to 10 % or less of the initial concentration

Conclusions:

No abiotic degradation of the test item was observed. Ditolylether was found to be stable at 50 °C at pH 4, 7 and 9.

Executive summary:

The tests were performed according to OECD Guidelines for Testing of Chemicals, Section 1 – Physical-Chemical Properties, OECD TG 111 (2004). The hydrolysis behaviour of the test item Ditolylether was investigated at 50 °C at pH 4, pH 7 and pH 9 over a period of five days according to OECD TG 111. The stability was monitored after diethyl ether extraction by GC analysis using MS-detection. No abiotic degradation of the test item was observed. Consequently, Ditolylether is assumed to be stable at 50 °C and, thus, as well as at 25 °C, no half-life times and hydrolysis rates were calculated.

According to OECD 111 Guideline sterility tests were conducted at the end of the hydrolysis tests. No microbes (colonies) were found. Therefore biotic degradation can also be excluded.

Description of key information

No abiotic degradation of the test item was observed. Ditolylether was found to be stable at 50 °C and pH 4, 7 and 9. 

Additional information

The recovery of the test substance was slightly below the criterion of 90 % at pH 7 which would in general be interpreted as hydrolytic degradation. However, if any, hydrolytic degradation would be expected at pH 4 as ether cleavage only occurs under acidic conditions. Cresols would be the hydrolysis products expected at pH 4 but could not be detected using the GC twister method (p-cresol was calibrated as representative substance for the cresols). Thus, it is even more unlikely that abiotic degradation took place at pH 7.

Consequently, Ditolylether is assumed to be stable at 50 °C and, thus, as well as at 25 °C, no half-life times and hydrolysis rates were calculated.