Acetoacetamide

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018

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

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:

About 90 mg were given into a 100 ml volumetric flask. Afterwards the flask was brought to volume with
buffer solution. The concentration of the test item in the test solutions was about 900 mg/L and did not
exceed 0.01 M or the half saturation concentration.

Buffers:

Citrate buffer pH 4 (0.05 M):
Per 1 L ultra-pure water 10.506 g citric acid monohydrate was weighed and 60 ml of sodium hydroxide
solution (1 M) was added to reach pH 4.
The pH value of the buffer solution was determined to be 4.00.
Phosphate buffer pH 7 (0.05 M):
Per 1 L ultra-pure water 6.854 g Potassium dihydrogenphosphate was weighed and 30 ml of sodium
hydroxide solution (1 M) was added to reach pH 7.
The pH value of the buffer solution was determined to be 7.00.
Borate buffer pH 9 (0.05 M):
Per 1 L ultra-pure water 3.097 g boric acid and 3.780 g potassium chloride was weighed and 21 ml of
sodium hydroxide solution (1 M) was added to reach pH 9.
The pH value of the buffer solution was determined to be 9.00.
The pH values of the buffer solutions used during the test were determined with a calibrated pH meter with a
precision of 0.01 pH units.

Details on test conditions:

Photolytic interference was avoided by shaking in the dark.
All suitable precautions were taken to exclude dissolved oxygen (degassing the buffers with argon for at least five minutes and
purging the vessels with argon before preparing the test solution).
Sterile buffer solutions were used.
The temperature was kept and measured with a resolution of ± 0.1 °C.

Duration:

120 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

903 mg/L

Duration:

120 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

936 mg/L

Duration:

120 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

895 mg/L

Number of replicates:

2

Positive controls:

not specified

Negative controls:

yes

Remarks:

Two blank samples of each buffer matrix

Statistical methods:

Not mentioned.

Preliminary study:

A preliminary test was performed at 50± 0.5 oc at three pH values 4, 7 and 9. A sufficient number of measurements were made, in order to be able to
estimate whether for each pH value and at 50 oc, less than 10 % of hydrolysis is observed after 120 hours or not.
Samples were taken at to and after 5 days (tsd) and treated as described in chapter 3. 7. The samples were measured together in one sequence
after sampling at tsd·

Test performance:

No main test was performed because less than 10% of hydrolysis was observed after 5 days at pH 4, 7 and
9. Therefore the test item is considered to be hydrolytically stable.

Transformation products:

not specified

Key result

pH:

7

Temp.:

50 °C

DT50:

> 1 yr

Type:

not specified

Remarks on result:

hydrolytically stable based on preliminary test

Accuracy:

To determine the accuracy of the analytical method recovery experiments for the active ingredient in water were performed. A low spike solution was prepared containing 61.1 mg/L of Acetoacetamide in diluent and a high spike

solution was prepared containing 1221 mg/L in diluent. For each buffer matrix (pH 4, pH 7 and pH 9) two recovery samples for each level were prepared.

Low Recovery:

Concentration in the low recovery samples: 30.5 mg/L (61.1 mg/L regarding a dilution factor of 2) Acetoacetamide: 2.0 ml of the buffer solution and 2.0 ml of the low spike solution were mixed. The samples were directly used for analysis.

This is equal to 7 % of the nominal start concentration used in the preliminary test.

High Recovery:

Concentration in the high recovery samples: 610.5 mg/L (1221 mg/L regarding a dilution factor of 2) Acetoacetamide: 2.0 ml of the buffer solution and 2.0 ml of the high spike solution were mixed. The samples were directly used for analysis.

This is equal to 136 % of the nominal start concentration used in the preliminary test.

Validity criteria fulfilled:

yes

Conclusions:

The hydrolysis of Acetoacetamide is negligible at pH 4, pH 7 and pH 9. The degradation of Acetoacetamide was less than 10% at pH 4, pH 7 and pH 9 at 50°C over a period of 120 hours.
Therefore, the corresponding half-life time can be estimated to be longer than one year at 25 °C.

Executive summary:

The study was performed in year 2018 according to OECD Guideline 111 and EU Method C.7.

The hydrolysis of Acetoacetamide is negligible at pH 4, pH 7 and pH 9. The degradation of Acetoacetamide

was less than 10% at pH 4, pH 7 and pH 9 at 50°C over a period of 120 hours. Therefore, the

corresponding half-life time can be estimated to be longer than one year at 25 °C.

Description of key information

The hydrolysis of Acetoacetamide is negligible at pH 4, pH 7 and pH 9. The degradation of Acetoacetamide

was less than 10% at pH 4, pH 7 and pH 9 at 50 oc over a period of 120 hours. Therefore, the

corresponding half-life time can be estimated to be longer than one year at 25 °C.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C