3β-hydroxyandrost-5-en-17-one acetate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-06-14 to 2017-08-24

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

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: M16GB2547
- Expiration date of the lot/batch: 2018-07-01 (retest date)
- Purity test date: 2016-08-28 (certificate of analysis release date)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature
- Stability under test conditions: no data

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products:
* Tier 1: at the beginning and after 5 days.
* Tier 2: at the beginning and at several sampling points after t=0.

- Sampling method:
* Tier 1: Concentration of the test item in the test sample was determined immediately after preparation. The samples taken at t=5 days were cooled to room temperature using running tap water. The samples were diluted in a 1:1 (v:v) ratio with acetonitrile and analysed.

Buffers:

- pH:
* Tier 1: 4.0, 7.0 and 9.0
* Tier 2: 4.0, 7.0 and 9.0

- Type, final molarity and composition of buffer:
* buffer pH 4: solution of 16.7% 0.1 M sodium acetate in water and 83.3% 0.1 M acetic acid in water. The buffer contains 0.0009% (w/v) sodium azide.
* buffer pH 7: solution of 0.1 M potassium di-hydrogen-phosphate in water adjusted to pH 7 using 10N sodium hydroxide. The buffer contains 0.0009% (w/v) sodium azide.
* buffer pH 9: solution of 0.1 M boric acid in water and 0.1 M potassium chloride in water adjusted to pH 9 using 10N sodium hydroxide. The buffer contains 0.0009% (w/v) sodium azide.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: sterile vessel
- Sterilisation method: buffer solutions were filter-sterilised through a 0.2 µm FP 30/0.2 CA-S filter (Wathman, Dassel, Germany) and transferred into a sterile vessel.
- Lighting: in the dark
- Measures taken to avoid photolytic effects: vessels placed in the dark
- Measures to exclude oxygen: nitrogen gas was purged through the solution for 5 minutes
- Details on test procedure for unstable compounds: no data
- Details of traps for volatile, if any: not applicable
- If no traps were used, is the test system closed/open: under vacuum
- Is there any indication of the test material adsorbing to the walls of the test apparatus? no

TEST MEDIUM
- Volume used/treatment: 6 mL
- Kind and purity of water: Milli-Q
- Preparation of test medium: The test item was spiked to the solutions at a target concentration of 0.300 mg/L using a spiking solution in methanol.
- Renewal of test solution: not applicable
- Identity and concentration of co-solvent: not applicable

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Dissolved oxygen: no data

Duration:

5 d

pH:

4

Temp.:

49 °C

Initial conc. measured:

> 0.223 - < 0.236 mg/L

Duration:

5 d

pH:

7

Temp.:

49 °C

Initial conc. measured:

> 0.228 - < 0.259 mg/L

Duration:

5 d

pH:

9

Temp.:

49 °C

Initial conc. measured:

> 0.227 - < 0.229 mg/L

Duration:

763.35 h

pH:

4

Temp.:

20 °C

Initial conc. measured:

> 0.271 - < 0.288 mg/L

Duration:

763.5 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

> 0.244 - < 0.246 mg/L

Duration:

741.03 h

pH:

4

Temp.:

60 °C

Initial conc. measured:

> 0.261 - < 0.269 mg/L

Duration:

791.4 h

pH:

7

Temp.:

20 °C

Initial conc. measured:

> 0.26 - < 0.265 mg/L

Duration:

791.58 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

> 0.264 - < 0.268 mg/L

Duration:

741.25 h

pH:

7

Temp.:

60 °C

Initial conc. measured:

> 0.226 - < 0.238 mg/L

Duration:

813.95 h

pH:

9

Temp.:

20 °C

Initial conc. measured:

> 0.217 - < 0.236 mg/L

Duration:

147.07 h

pH:

9

Temp.:

40 °C

Initial conc. measured:

> 0.21 - < 0.213 mg/L

Duration:

47.88 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

> 0.245 - < 0.273 mg/L

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Statistical methods:

For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% were plotted against time. At all temperatures linear relationships were obtained. The half-life times of the test item were determined according to the model for pseudo-first order reactions. All logarithms of the relative concentrations were correlated with time using linear regression analysis.
The rate constant (kobs) and half-life time of the test item at each temperature was obtained and the Arrhenius equation was used to determine the rate constant and half-life time at 25°C.

Preliminary study:

At pH 4, pH 7 and pH 9, the test item concentration decreased ≥ 10% within 5 days. According to the guideline, the higher Tier test was required to determine the half-life time of the test item.

Transformation products:

no

% Recovery:

25

pH:

4

Temp.:

50 °C

Duration:

5 d

% Recovery:

46

pH:

7

Temp.:

50 °C

Duration:

5 d

% Recovery:

> 90 - < 96

pH:

4

Temp.:

20 °C

Duration:

763.35 h

% Recovery:

> 81 - < 82

pH:

4

Temp.:

50 °C

Duration:

763.5 h

% Recovery:

> 87 - < 90

pH:

4

Temp.:

60 °C

Duration:

741.03 h

% Recovery:

> 87 - < 88

pH:

7

Temp.:

20 °C

Duration:

791.4 h

% Recovery:

> 88 - < 89

pH:

7

Temp.:

50 °C

Duration:

791.58 h

% Recovery:

> 75 - < 79

pH:

7

Temp.:

60 °C

Duration:

741.25 h

% Recovery:

> 72 - < 79

pH:

9

Temp.:

20 °C

Duration:

813.95 h

% Recovery:

> 70 - < 71

pH:

9

Temp.:

40 °C

Duration:

147.07 h

% Recovery:

> 82 - < 91

pH:

9

Temp.:

50 °C

Duration:

47.88 h

pH:

4

Temp.:

25 °C

DT50:

218 d

Type:

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

Key result

pH:

7

Temp.:

25 °C

DT50:

122 d

Type:

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

pH:

9

Temp.:

25 °C

DT50:

8.3 d

Type:

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

Validity criteria fulfilled:

yes

Remarks:

No test item was detected in the blank buffer solutions. The mean recoveries of the buffer solutions fell within the criterion range of 70-110%. It demonstrated that the analytical method was adequate to support the hydrolysis study on the test item.

Conclusions:

The preliminary test (Tier 1) and main study (Tier 2) were performed for the determination of the rate of hydrolysis of T008506 at pH values normally found in the environment (ph 4-9) (OECD 111). The half-life times of T008506 at 25°C were 218 days, 122 days and 8.3 days at pH 4, 7 and 9 respectively. The results of the study can be considered reliable without restriction.

Description of key information

One study (Ciric, 2017) was performed according to OECD guideline 111 and regarded as a key study (Klimisch score of 1).

A preliminary test was performed at 50°C at pH 4.0, 7.0 and 9.0. As the test item was found to be not stable according to the criteria given in the guideline, a main test was performed.

A half-life time of 122 days at 25 °C and pH 7 was determined for T008506.

Key value for chemical safety assessment

Half-life for hydrolysis:

122 d

at the temperature of:

25 °C