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Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July from the 06th to the 12th, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Reason / purpose for cross-reference:

reference to other study

Remarks:

validated analytical method

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Version / remarks:

adopted 13 April 2004

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 (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Concentration of the test item was determined at the start and at the end of incubation period (after 5 days).

Buffers:

Buffer solutions were prepared using reagent grade chemicals and ultrapure, sterile water.
Compositions of the buffer solutions:
pH 4.0: 1 ml 0.2 M Sodium hydroxide and 5.105 g Potassium hydrogen phthalate were diluted to 500 ml with ultrapure water.
pH 7.0: 74 ml 0.2 M Sodium hydroxide and 3.400 g Potassium dihydrogen phosphate were diluted to 500 ml with ultrapure water.
pH 9.0: 53.5 ml 0.2 M Sodium hydroxide and 1.550 g Boric acid and 1.876 g Potassium chloride were diluted to 500 ml with ultrapure water.

Details on test conditions:

SOLUTIONS FOR CALIBRATION
- Stock solution of test item: 1 mg/ml dissolved in ultrapure water.
- Work Solution: 10 µg/ml test item, diluted from Stock Solution with ultrapure water.
- Calibration series: 7 calibration standard solutions were prepared each day of the analytical occasions. The stock solution and work solution were properly diluted with ultrapure water.
- Nominal concentrations: 0.1, 0.2, 0.5, 1, 2, 5, and 10 µg/ml.

TEST PROCEDURES and CONDITIONS
- Sterilisation: all glassware, water and buffer solution were sterilised.
- Test solution: 20.0 mg test item was dissolved in 10 ml Ultrapure Water and spiked in Buffer solutions (pH = 4, 7 and 9) at 20 mg/l concentration level.
- Lighting: dark thermostat was used to avoid photolytic effects.
- Oxygen: nitrogen was bubbled into the water for five minutes before the preparation of the solutions in order to exclude oxygen.
- Storage conditions: samples were stored at a temperature of 50 °C in screw-cap glass tubes with PTFE septa.

MEASUREMENTS
The pH of each buffer solution was checked with a calibrated pH meter at the start and at the end of the test.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

18.2 mg/L

Remarks:

17.9 - 18.6 mg/l

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

19.3 mg/L

Remarks:

18.7 - 19.8 mg/l

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

19.2 mg/L

Remarks:

19.0 - 19.4 mg/l

Number of replicates:

7 samples of ca. 25 ml per buffer solution.

Negative controls:

yes

Remarks:

control buffer

Preliminary study:

Based on the results of the preliminary test, the hydrolysis rate of test item was found to be lower than 10 % at pH 4, at pH 7 and at pH 9 after 5 days at 50 °C, therefore the test item is considered to be hydrolytically stable.

Transformation products:

not measured

Remarks on result:

hydrolytically stable based on preliminary test

Remarks:

hydrolysis rate of test item was found to be lower than 10 % at pH 4, at pH 7 and at pH 9 after 5 days at 50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Measured data at the start and after 5 days in buffer solution pH 4

pH	Sampling time (days)	Concentration of test item (mg/l )		End / Start (%)	Measured pH
		Results of the replicates	Mean
4	Start	Control buffer		-	4.04
		18.0	18.2	-	4.04
		18.2			4.03
		18.5			4.03
		18.6			4.04
		17.9			4.04
	5	Control buffer		-	4.01
		18.1	18.8	103	4.01
		18.5			4.01
		18.9			4.01
		19.0			4.01
		19.4			4.01

Measured data at the start and after 5 days in buffer solution pH 7

pH	Sampling time (days)	Concentration of test item (mg/l )		End / Start (%)	Measured pH
		Results of the replicates	Mean
7	Start	Control buffer		-	7.02
		18.7	19.3	-	7.04
		19.0			7.04
		19.5			7.04
		19.3			7.04
		19.8			7.04
	5	Control buffer		-	6.99
		20.4	20.1	105	7.01
		20.3			7.01
		20.3			7.01
		20.2			7.01
		19.5			7.01

Measured data at the start and after 5 days in buffer solution pH 9

pH	Sampling time (days)	Concentration of test item (mg/l )		End / Start (%)	Measured pH
		Results of the replicates	Mean
9	Start	Control buffer		-	9.03
		19.0	19.2	-	9.05
		19.0			9.05
		19.2			9.05
		19.4			9.06
		19.2			9.05
	5	Control buffer		-	9.03
		20.4	20.5	107	9.03
		20.5			9.04
		20.4			9.03
		20.4			9.03
		20.6			9.03

Conclusions:

Test item is hydrolytically stable.

Executive summary:

The hydrolysis potential of the test item was assayed following the procedures outlined into the OECD guideline 111.

The content of test item in the different pH buffer samples was determined at the beginning and the end of the test period. Five samples were analysed at the start of the study. The samples were measured after dilution (tenfold) with ultrapure water. Two samples were taken from five separate tubes of the hydrolysis test after 5 days storage period and analysed by HPLC. Samples were diluted tenfold with ultrapure water before analysis. Three samples were taken from the control vessels at the start and at the end of the storage and these were measured in the same way as the samples without dilution.

Based on the results of the preliminary test, the hydrolysis rate of test item was found to be lower than 10 % at pH 4, at pH 7 and at pH 9 after 5 days at 50 °C, therefore the test item is considered to be hydrolytically stable.

Conclusion

Test item is hydrolytically stable.

Description of key information

Test item is hydrolytically stable.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

50 °C

Additional information

The hydrolysis potential of the test item was assayed following the procedures outlined into the OECD guideline 111. The content of test item in the different pH buffer (i.e. at pH 4, 7 and 9) samples was determined at the beginning and the end of the test period; the analysis was performed after 5 days of storage under dark conditions and at the temperature of 50 °C. The test item concentrations were determined using suitable HPLC-VIS method, previously validated.

Based on the results of the preliminary test, the hydrolysis rate of test item was found to be lower than 10 % at pH 4, at pH 7 and at pH 9 after 5 days at 50 °C, therefore the test item is considered to be hydrolytically stable.