Tributylethylammonium ethyl sulphate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 15 February 2017 to 14 July 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Version / remarks:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

PREPARATION OF THE SAMPLES
- Test item was spiked to the buffers. Target concentration: 400 µg/L.
- For each sampling time, duplicate vessels under vacuum were filled with 6 mL test solution.
- The vessels were placed in a temperature controlled environment (50.3°C ± 0.1°C).
- Blank buffers were treated similarly as the test samples.

SAMPLING DETAILS
- Samples for analysis were taken immediately after preparation (t=0).
- Samples for analysis (except for the blanks) were taken at t= 5 days.
- The samples taken at t= 5 days were cooled to room temperature using running tap water.

pH MEASUREMENTS
The pH of the test solutions (except for the blanks) was determined at each sampling point.

Buffers:

Buffer pH 4: 16.7% 0.01 M sodium acetate and 83.3% 0.01 M acetic acid in water.

Buffer pH 7: 0.01 M potassium di-hydrogenphosphate in water adjusted to pH 7 using 1 N sodium hydroxide.

Buffer pH 9: 0.01 M boric acid and 0.01 M potassium chloride in water adjusted to pH 9 using 1 N sodium hydroxide.

Details:
- Sodium azide content in each buffer: 0.0009% (w/v)
- Kind of water: tap water purified by a purification system (Milli-Q, Millipore)

Details on test conditions:

TEST SYSTEM
- Sterilisation method: Each buffer was filter-sterilised through a 0.2 µm FP 30/0.2 CA-S filter (Whatman) and transferred into a sterile vessel.
- Measures to exclude oxygen: nitrogen gas was purged through the sterile buffers for 5 minutes prior to preparation of the blank and test solutions.
- Measures taken to avoid photolytic effects: the test vessels were kept in the dark.

TEST MEDIUM
- Identity and concentration of co-solvent: a spiking solution in 50/50 (v/v) acetonitrile/water was used. The spiking volume was < 1% of the sample volume. Nominal concentrations were not corrected for the spiking volume.

Duration:

5 d

pH:

4.1

Temp.:

50 °C

Initial conc. measured:

342 µg/L

Remarks:

Mean (n=2) conc. Based on the anion.

Duration:

5 d

pH:

4.1

Temp.:

50 °C

Initial conc. measured:

437 µg/L

Remarks:

Mean (n=2) conc. Based on the cation.

Duration:

5 d

pH:

7.1

Temp.:

50 °C

Initial conc. measured:

408 µg/L

Remarks:

Mean (n=2) conc. Based on the anion.

Duration:

5 d

pH:

7.1

Temp.:

50 °C

Initial conc. measured:

461 µg/L

Remarks:

Mean (n=2) conc. Based on the cation.

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

404 µg/L

Remarks:

Mean (n=2) conc. Based on the anion.

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

442 µg/L

Remarks:

Mean (n=2) conc. Based on the cation.

Number of replicates:

Two

Positive controls:

no

Negative controls:

no

Preliminary study:

At pH 4, 7 and pH 9, a degree of hydrolysis < 10% was observed after 5 days at 50°C (half-life time at 25°C is > 1 year). No further tests were required.

Test performance:

RECOVERIES
- Recovery is the concentration analysed at t=0 relative to the nominal concentration.
- The mean (n=2) recovery at each pH was calculated (see table below).

- The mean recovery of the test item (based on cation) at pH 7 fell slightly outside the acceptable range of 70-110% for non-labelled chemicals. The mean recoveries (based on anion) at all pH’s and cation (pH 4 and 9) fell within the acceptable range of 70-110%. It demonstrated that the analytical method was adequate to support the hydrolysis study on the test item.

- The concentrations analysed in the test samples were not corrected for recovery.

Transformation products:

no

% Recovery:

85

pH:

4.1

Temp.:

50 °C

Duration:

0 h

Remarks on result:

other: Mean (n=2) recovery, based on the anion.

% Recovery:

109

pH:

4.1

Temp.:

50 °C

Duration:

0 h

Remarks on result:

other: Mean (n=2) recovery, based on the cation.

% Recovery:

102

pH:

7.1

Temp.:

50 °C

Duration:

0 h

Remarks on result:

other: Mean (n=2) recovery, based on the anion.

% Recovery:

115

pH:

7.1

Temp.:

50 °C

Duration:

0 h

Remarks on result:

other: Mean (n=2) recovery, based on the cation.

% Recovery:

101

pH:

9

Temp.:

50 °C

Duration:

0 h

Remarks on result:

other: Mean (n=2) recovery, based on the anion.

% Recovery:

110

pH:

9

Temp.:

50 °C

Duration:

0 h

Remarks on result:

other: Mean (n=2) recovery, based on the cation.

Key result

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Conclusions:

The substance is hydrolytically stable at pH 4, 7 and 9 (half-life time at 25°C is > 1 year).

Executive summary:

The rate of hydrolysis of the substance at pH values normally found in the environment (pH 4, 7 and 9) was determined in a GLP-compliant study according to EC C.7, OECD 111 and EPA OPPTS 835.2120. A degree of < 10% of hydrolysis was observed at pH 4, 7 and 9 after 5 days at 50°C (Tier 1). This corresponds with a half-life time at 25°C of > 1 year. The substance is hydrolytically stable at pH 4, 7 and 9.

Description of key information

Hydrolytically stable at pH 4, 7 and 9 (half-life time at 25°C: > 1 year).

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

The rate of hydrolysis of the substance at pH values normally found in the environment (pH 4, 7 and 9) was determined in a GLP-compliant study according to EC C.7, OECD 111 and EPA OPPTS 835.2120. A degree of < 10% of hydrolysis was observed at pH 4, 7 and 9 after 5 days at 50°C (Tier 1). This corresponds with a half-life time at 25°C of > 1 year. The substance is hydrolytically stable at pH 4, 7 and 9.