Estr-4-ene-3,17-dione

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

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

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- pH of the blank buffer solution: checked at the beginning of the test
- pH of the hydrolysis solution: measured at each test point
- Temperature during the experiment: checked at each test point
- The repeatability of the peak areas of the investigated components was checked by analyzing an independent control solution of the test item
- Suitability of the HPLC system during the hydrolysis study: verified on every day of application
- Calibration: verified at each day of analysis at the level of 90.22 mg/L by using a control calibration solution

Buffers:

BUFFERS:
- Buffer pH 4: Citric acid/NaOH/NaCl (Fluka, Order no.: 33643)
- Buffer pH 7: KH2PO4/Na2HPO4 (Fluka, Order no.: 33646)
- Buffer pH 9: Na2B4O7/HCl (Fluka, Order no.: 33648)

Details on test conditions:

TEST DESIGN:
- 230.8 mg of the test item was weighed in a 25 mL measuring flask which was then filled to the mark with acetonitrile, resulting in a final concentration of approx. 9.21 g/L
- For each pH separate hydrolysis test solutions were prepared by dilution of 1 mL of the test item stock solution with 100 mL of the corresponding buffer systems
- Solubility and test concentration: aqueous solution (including 1 % acetonitrile) with a concentration of approx. 95 mg/L (WSL: 191 mg/L)
- Test item concentration: 92.14 mg/L
- Preparation was carried out under nitrogen as flushing gas
- The vials were closed and incubated at 50 °C in a water bath under dark
- At each test point the hydrolysis solution was directly led to the chromatographic measurement
- pH determination: pH-meter equipped with a calibrated single-rod glass electrode

Duration:

5 d

pH:

4

Temp.:

50

Initial conc. measured:

92.213 mg/L

Duration:

5 d

pH:

7

Temp.:

50

Initial conc. measured:

91.579 mg/L

Duration:

5 d

pH:

9

Temp.:

50

Initial conc. measured:

92.409 mg/L

Number of replicates:

None

Transformation products:

no

% Recovery:

97.8

pH:

4

Temp.:

50 °C

Duration:

5 d

% Recovery:

98.3

pH:

7

Temp.:

50 °C

Duration:

5 d

% Recovery:

95.6

pH:

9

Temp.:

50 °C

Duration:

5 d

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: estimated (see "Details for result")

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: estimated (see "Details for result")

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: estimated (see "Details for result")

Details on results:

The overall degradation of the test item observed at 50 °C after 5 days at pH 4, 7 and 9 was less than 10 %. The test item is therefore considered to be stable at 50 °C. Therefore the substance can be considered hydrolytically stable, i.e. ty, > 1 year at 25 °C. Because no degradation was observed, no sterility test was performed in this case. No further tests at other temperatures are required for pH 4, 7 and 9.

Validity criteria fulfilled:

yes

Conclusions:

The substance can be considered to be hydrolytically stable at pH 4, 7 and 9 at 25 °C.

Executive summary:

The test was performed according to OECD Guidelines for Testing of Chemicals, Section 1 "Physical-Chemical Properties, OECD TG 111, Council Regulation (EC) No 440/2008, Guideline Part C" Methods for the Determination of Ecotoxicity, C.7. "Abiotic Degradation: Hydrolysis as a Function of pH" The hydrolysis behaviour of the test item 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 by HPLC analysis using UV-detection. After 5 days no abiotic degradation of the test item was observed. The substance was found to be stable at 50 °C at all three pH-values. Therefore it can be assumed that the test item is also stable at 25 °C and no half-life times and hydrolysis rates were calculated.

Description of key information

The substance is hydrolytically stable at pH 4, pH 7 and pH 9 (25°C).

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

"Should read: > 1 year at 25 °C"

No hydrolytic degradation was observed within 5 days at pH 4, 7 and 9 at 50 °C. Therefore no further testing was required and the substance can be considered to be hydrolytically stable at pH 4, 7 and 9 and 25 °C.

This notion is also experimentally supported by the results of a hydrolysis study with estr-4 -ene-3,17 -dione which is structurally similar. Estr-4-ene-3,17-dione was found to be hydrolytically stable in the pH region 4 - 9 and 25 °C.