6-ethyl-5-fluoro-4(3H)-pyrimidone

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 1998-11-11 to 1998-11-18

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

Specific details on test material used for the study:

Batch No.: 960509
Purity: 92.3%

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling method:
After the test solution prepared, an aliquot (ca 30 mL) of each solution was poured into a stoppered bottle and placed in the 20°C water bath for approximately 5 minutes prior to analysis.
After 2.4 hours and 5 days, an aliquot (ca 30 mL) of each solution was taken and cooled to 20°C prior to analysis.

- Sampling intervals/times for pH measurements: At the end of the five day test period, the pH of the remainder of each test solution was measured at 50°C.

Buffers:

- pH: 4, 7 & 9

PREPARATION OF BUFFER SOLUTIONS
- pH 4 buffer:
0.1M potassium hydrogen phthalate solution was adjusted to pH 4.0 with 1M hydrochloric acid, with the temperature of the buffer solution at 50°C ± 0.5°C.
- pH 7 buffer:
0.1M potassium dihydrogen orthophosphate solution was adjusted to pH 7.0 with 1M sodium hydroxide, with the temperature of the buffer solution at 50°C ± 0.5°C.
- pH 9 buffer:
0.1M solution of potassium chloride and boric acid was adjusted to pH 9.0 with 1M sodium hydroxide, with the temperature of the buffer solution at 50°C ± 0.5°C.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 100 mL volumetric flasks
- Sterilisation method: Prior to the test, the volumetric flasks were rinsed with ethanol and allowed to drip dry
- Measures taken to avoid photolytic effects: flasks were covered in aluminium foil to exclude light
- If no traps were used, is the test system: closed

TEST MEDIUM
- Volume used/treatment: 100 mL
- Preparation of test medium: The buffer solutions were autoclaved at 122°C for 17 minutes and then purged with nitrogen for 10 minutes prior to use.
- Renewal of test solution: not renewed

OTHER TEST CONDITIONS
- Adjustment of pH: no

Number of replicates:

2

Negative controls:

yes

Remarks:

Flasks containing buffer solution only (one at each pH) were treated in the same manner as with the test solutions.

Preliminary study:

No hydrolysis was observed under the test conditions at any pH.
0.3, 0.5, 0.9% hydrolysis occurring in 5 days at 50°C at pH 4, 7, 9, respectively.
0.2, 0, 0% hydrolysis occurring in 2.4 hours at 50°C at pH 4, 7, 9, respectively.

Transformation products:

not measured

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Type:

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

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Type:

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

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Type:

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

Validity criteria fulfilled:

yes

Conclusions:

The test item possesses half-life times of greater than 1 year at pH 4, 7 and 9 at 25°C.

Executive summary:

The study was performed to obtain estimates of the rate of hydrolysis of the test item under pH conditions relevant to the environment. The test was performed in accordance with the preliminary test as described in the OECD Method 111.

After a period of 5 days at 50°C, the test item underwent no significant hydrolysis at pH 4, 7 and 9.

The results indicate that at 25°C, the test item will possess half-life times of greater than 1 year at pH 4, 7 and 9.

Description of key information

The study was performed to obtain estimates of the rate of hydrolysis of the test item under pH conditions relevant to the environment. The test was performed in accordance with the preliminary test as described in the OECD Method 111.

After a period of 5 days at 50°C, the test item underwent no significant hydrolysis at pH 4, 7 and 9.

The results indicate that at 25°C, the test item will possess half-life times of greater than 1 year at pH 4, 7 and 9.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C