6-amino-1,3-dimethyluracil

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-07-01 - 2002-08-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

under GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Version / remarks:

OECD Guideline for Testing of Chemicals No. 111, "Hydrolysis as a Function of pH"; adopted May 12, 1981. (only at pH 4.0, pH 7.0 and pH 9.0)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

EEC Directive 92/69, Section C.7, "Abiotic Degradation: Hydrolysis as a Function of pH", L383 A, December 1992.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature (at about 20 °C)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

After incubation 20 µl aliquots of the test solutions at each pH value were analysed without dilution by measuring the UV/VIS signal of 1,3-Dimethyl-4-aminouracil after HPLC separation of the injected sample solution.

Buffers:

- pH: 4, 7, 9
- Type and final molarity of buffer:
Buffer pH 4, Biphthalate, Baker, Art. No. 5657
Buffer pH 7, Phosphate, Baker, Art. No. 5656
Buffer pH 9, Borate, Baker, Art. No. 7145

The buffer solutions were sterilized for 25 minutes in an autoclave prior to first use. Nitrogen was passed through the buffer solutions for 3 minutes except when freshly sterilized.

Details on test conditions:

TEST SYSTEM
- Sterilisation method: All glassware, which must be inert in the pH range applied, was rinsed with sterile buffer. The hydrolysis was carried out in flasks, which were stoppered or sealed with an inert material (e. g. PTFE).

TEST DESIGN

Method
The study was conducted as described in the guidelines.
The test item was dissolved in the buffer solutions and incubated at 50 °C with the water bath kept constant at 土 0.1 °C, usually. The concentration of the test item was determined as a function of time at each pH.

Performance of the Test
A preliminary test was performed at 50 °C ±0.1 °C at each of pH 4.0, pH 7.0 and pH 9.0. Aliquots of each test solution were analysed in time intervals using the analytical method as described later in this report. Analysis was performed before incubation, after 2.4 hours, 24 hours, 48 hours and after 120 hours.

Preparation of the Test Solutions
pH 4.0
A 10.95 mg sample of 1,3-Dimethyl-4-aminouracil was dissolved in 100 ml buffer solution (pH 4.0) to prepare a test solution of 109.5 µg/ml 1,3-Dimethyl-4-aminouracil. This mixture was ultrasonificated for 3 minutes and submitted to a 0.45 µm filtration. Two aliquots of this test solution of approximately 50 ml each were transferred into 50 ml Erlenmeyer flasks in order to perform a duplicate test.
pH 7.0
A 13.48 mg sample of 1,3-Dimethyl-4-aminouracil was dissolved in 100 ml buffer solution (pH 7.0) to prepare a test solution of 134.8 µg/ml 1,3-Dimethyl-4-aminouracil. This mixture was ultrasonificated for 3 minutes and submitted to a 0.45 µm filtration. Two aliquots of this test solution of approximately 50 ml each were transferred into 50 ml Erlenmeyer flasks in order to perform a duplicate test.
pH 9.0
A 11.17 mg sample of 1,3-Dimethyl-4-aminouracil was dissolved in 100 ml buffer solution (pH 9.0) to prepare a test solution of 111.7 µg/ml 1,3-Dimethyl-4-aminouracil. This mixture was ultrasonificated for 3 minutes and submitted to a 0.45 µm filtration. Two aliquots of this test solution of approximately 50 ml each were transferred into 50 ml Erlenmeyer flasks in order to perform a duplicate test.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

>= 111.6 - <= 116.5 mg/L

Remarks:

duplicate determination

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

>= 131.3 - <= 140.1 mg/L

Remarks:

duplicate determination

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

>= 140.8 - <= 141.5 mg/L

Remarks:

duplicate determination

Number of replicates:

duplicate determination

Positive controls:

no

Negative controls:

no

Preliminary study:

The results of pH 4.0, pH 7.0 and pH 9.0 showed no significant degradation of 1,3-Dimethyl-4-aminouracil at 50 °C after 5 days.

Transformation products:

no

Key result

pH:

4

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

7

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

9

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Validity criteria fulfilled:

not specified

Conclusions:

The study was conducted according to OECD 111 under GLP and is well documented. Hence, the results can be considered as sufficiently reliable to asses the susceptibility towards hydrolysis of 1,3-Dimethyl-4-aminouracil. The results of pH 4.0, pH 7.0 and pH 9.0 showed no significant degradation of 1,3-Dimethyl-4-aminouracil at 50 °C. The degradation of 1,3-Dimethyl-4-aminouracil was less than 10 % after 5 days. According to the EEC Directive 92/69, Section C.7, it can be concluded, that the estimated half-life time is higher than one year under representative environmental conditions (25°C). Therefore, 1,3-Dimethyl-4-aminouracil was considered to be hydrolytically stable, and no further testing was necessary.

Executive summary:

The hydrolysis determination of 1,3-Dimethyl-4-aminouracil under GLP at different pH values was based on the OECD Guideline No. 111,"Hydrolysis as a Function of pH"; adopted May 12, 1981 and on the EEC Directive 92/69, Section C.7, "Abiotic Degradation: Hydrolysis as a Function of pH",L383 A, December 1992.

The results of pH 4.0, pH 7.0 and pH 9.0 showed no significant degradation of 1,3-Dimethyl-4-aminouracil at 50 °C. The degradation of 1,3-Dimethyl-4-aminouracil was less than 10 % after 5 days. These results were summarised in the table below.

 

pH	Hydrolysis after 5 days, 50 °C [%]
4.0	< 10
7.0	< 10
9.0	< 10

 

According to the EEC Directive 92/69, Section C.7 it can be concluded, that the estimated half-life time is higher than one year under representative environmental conditions (25°C). Therefore, 1,3-Dimethyl-4-aminouracil was considered to be hydrolytically stable, and no further testing was necessary.

Description of key information

Hydrolysis: hydrolytically stable, at pH 4.0, pH 7.0 and pH 9.0 at 50°C no significant degradation observed after 5 days (OECD 111, GLP)