2-amino-6-methyl-4-propyl-1,2,4-triazolo[1,5-a]pyrimidin-5(4H)-one

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP, available as unpublished report, minor restrictions in design and/or reporting but otherwise adequate for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

The hydrolysis of the test substance was investigated in sterile deionised glass-distilled water at concentrations of 5 and 50 ppm, in the dark at pH 5, 7, and 9 at 25 °C.

GLP compliance:

no

Radiolabelling:

yes

Analytical monitoring:

yes

Details on sampling:

Sub-samples (15mL) were withdrawn from all flasks at the time of application. Further samples were withdrawn from one flask of each type at 1, 3, 7, 14, and 26 days after application. These subsamples were stored at -15°C until required.

Details on test conditions:

STOCK SOLUTION:
A stock solution was prepared containing 3.65 µg/µL of the C14-radioactive labeled test substance.

TEST SOLUTIONS:
pH 7 and 9 solution were made from E.I.L. buffer powders. A pH 5 solution was made with a citrate buffer. Aliquots of these solutions (100mL) were transferred to conical flasks and they were sterilized in a Griffin and George autoclave.
After cooling to room temperature, aliquots of a test substance stock solution were added to the flask to make the solution. Duplicates of each solution were used. For the approximately 5 ppm solutions, 137 µL of the radiochemical stock solution was added to 100 mL in each flask. For the approximately 50 ppm solutions, 1274 µL of the radiochemical stock solution plus 100 µL of unlabelled stock solution (containing 96.7 mg of the unlabelled substance in 2.5 mL methanol) was added to 100 mL in each each flask. The flasks were stoppered, sealed with ‘parafilm’ and swirled at 25 °C in the dark.

DESCRIPTION OF SOLUTIONS USED FOR PH HYDROLYSIS STUDY:
- 1A & 1B: pH 5 solution containing 5 ppm test substance
- 2A & 2B: pH 5 solution containing 50 ppm test substance
- 3A & 3B: pH 7 solution containing 5 ppm test substance
- 4A & 4B: pH 9 solution containing 5 ppm test substance
- 5A & 5B: pH 9 solution containing 50 ppm test substance
- 6A & 6B: pH 9 solution containing 5 ppm test substance + 10000 ppm of “Gramoxone U.K.”

Duration:

26 d

pH:

9

Temp.:

25

Initial conc. measured:

50 other: ppm

Duration:

26 d

pH:

9

Temp.:

25

Initial conc. measured:

5 other: ppm

Duration:

26 d

pH:

7

Temp.:

25

Initial conc. measured:

5 other: ppm

Duration:

26 d

pH:

5

Temp.:

25

Initial conc. measured:

50 other: ppm

Duration:

26 d

pH:

5

Temp.:

25

Initial conc. measured:

5 other: ppm

Positive controls:

no

Negative controls:

no

Transformation products:

no

Remarks on result:

other: see "Details on results"

Details on results:

The calculated quantity of radioactivity present in the approximately 5 ppm solution was 2.34E+05 dpm/mL; in the 50 ppm solution the value was 4.68E+05 dpm/mL. Measurement of radioactivity during the experiment showed that there was no loss of radioactivity during a ca. 4 week period.

The autoradiograms of chromagrams showed that there was no significant degradation in any of the solutions 2A, 3A, 5A, and 6B after 7 and 26 days, and the radioactivity was counted as described previously.

Approximately 90% of the radioactivity applied to the plate was recovered and, of this approximately 95% was due to the C14-radioactive labeled test substance. These figures were similar for the 7 and 26 day chromatograms.

The results show that the test substance is stable to hydrolysis at room temperature between pH 5 and 9. This range includes all likely natural water pH’s and so purely chemical breakdown is unlikely under natural conditions.

The radioactivity present in the pH Hydrolysis studies expressed as a percentage of the calculated applied activity:

Solution	pH	Description	% of calculated activity at time after its addition (days)
			0	3	7	14	26
1A	5	5 ppm test substance	104	105	-	104	-
1B			105	-	109	-	110
2A	5	50 ppm test substance	105	-	104	-	106
2B			106	105	-	107	-
3A	7	5 ppm test substance	102	-	100	-	101
3B			145*	145.0	-	145	-
4A	9	5 ppm test substance	101	102	-	103	-
4B			105	-	104	-	104
5A	9	50 ppm test substance	104	-	101	-	106
5B			104	104	-	105	-
6A	9	5 ppm test substance plus 10,000 ppm ‘Gramoxone’	105.0	103	-	106	-
6B			104	-	102	-	102

* erroneous application.

Validity criteria fulfilled:

not applicable

Conclusions:

The results show that the test substance is stable to hydrolysis at room temperature between pH 5 and 9. This range includes all likely natural water pH’s and so purely chemical breakdown is unlikely under natural conditions.

Executive summary:

The hydrolysis of the test substance was investigated in sterile deionised glassdistilled water at concentations of 5 and 50 ppm, in the dark at pH 5, 7, and 9 at 25 °C. The calculated quantity of radioactivity present in the approximately 5 ppm solution was 2.34 E5 dpm/mL; in the 50 ppm solution the value was 4.68 E5 dpm/mL. Measurement of radioactivity during the experiment showed that there was no loss of radioactivity during a 4 week period. The autoradiograms of chromagrams showed that there was no significant degradation in any of the solutions after 7 and 26 days. Approximately 90% of the radioactivity applied to the plate was recovered and, of this approximately 95% was due to the C14-radioactive labeled test substance. These figures were similar for the 7 and 26 day chromatograms. The results show that the test substance is stable to hydrolysis at room temperature between pH 5 and 9. This range includes all likely natural water pH’s and so purely chemical breakdown is unlikely under natural conditions.

Description of key information

The substance is considered to be hydrolytically stable.

Additional information

The hydrolysis of the test substance was investigated in sterile deionised glass-distilled water at concentrations of 5 and 50 ppm, in the dark at pH 5, 7, and 9 at 25 °C. The calculated quantity of radioactivity present in the approximately 5 ppm solution was 2.34 E5 dpm/mL; in the 50 ppm solution the value was 4.68 E5 dpm/mL. Measurement of radioactivity during the experiment showed that there was no loss of radioactivity during a 4 week period. The autoradiograms of chromatograms showed that there was no significant degradation in any of the solutions after 7 and 26 days. Approximately 90% of the radioactivity applied to the plate was recovered and, of this approximately 95% was due to the C14-radioactive labelled test substance. These figures were similar for the 7 and 26 day chromatograms. The results show that the test substance is stable to hydrolysis at room temperature between pH 5 and 9. This range includes all likely natural water pH’s and so purely chemical breakdown is unlikely under natural conditions.