N-(2-ethoxyphenyl)-N'-(4-isododecylphenyl)oxamide

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to OECD guideline and GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products:
For pH 4, 7 and 9, samples were taken at test start (0 h) and at test end (120 h).
n general, the time between test item application and transfer to laboratory incubator/analysis did not exceed 30 minutes, but due to analytical reasons the analysis of the samples at test start had to be reinjected 35 minutes after application.

Buffers:

- pH: 1.2, 4, 7, 9
- Type and final molarity of buffer:
Buffer solution pH 4 45 mL of 0.1 mol/L NaOH were mixed with 250 mL 0.1 mol/L KH2-Citrate and diluted to 500 mL with double distilled water.

Buffer solution pH 7 148.15 mL of 0.1 mol/L NaOH were mixed with 250 mL 0.1 mol/L KH2PO4, diluted to 500 mL with double distilled water.

Buffer solution pH 9 106.5 mL of 0.1 mol/L NaOH were mixed with 250 mL 0.1 mol/L H3BO3 in 0.1 mol/L KCL, diluted to 500 mL with double distilled water.

Buffers were prepared on 2012-01-31, purged with nitrogen for 5 minutes and the pH was checked. The buffer solutions were sterilised by filtration through 0.22 µm.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: Sterile amber HPLC vials, volume: 4 mL
- Measures taken to avoid photolytic effects: Photolytic effects were avoided by exclusion of direct light
- Measures to exclude oxygen: Buffers were purged with nitrogen for 5 min, permanent nitogen flow during incubation
- Is there any indication of the test material adsorbing to the walls of the test apparatus? No
TEST MEDIUM
- Volume used/treatment: 4 mL
- Preparation of test medium: 1.8 mL of the respective sterile buffer were spiked to 1.5 mg/L with the test item stock solution into the test containers, sealed and transferred into the thermostat.
- Renewal of test solution: None

Duration:

120 h

Temp.:

50 °C

Initial conc. measured:

other: 2.78 % degradation at pH 9

Number of replicates:

test item: duplicates
control: single

Positive controls:

no

Negative controls:

yes

Remarks:

buffer solutions (pH 4, 7 and 9)

Test performance:

Chronological Test Description:
- Method validation
- Preparation of the sterile test solutions (experimental starting)
- Thermostatisation of the test solutions
- Analysis of samples
- Evaluation of reaction rate constants and half lives for the test
item

Transformation products:

no

Key result

Type:

not specified

Remarks on result:

not determinable

Remarks:

Reaction rate constants and half lives could not be calculated due to the fact that the test item undergoes no significant hydrolysis

Details on results:

TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes

Hydrolysis Results for the test item at pH 4 and 50 °C

Hydrolysis Time [hours]	Replicate	Concentration [mg/L]	Mean	Degradation [%]
0	1	1.44	1.44	-
	2	1.44
120	1	1.66	1.52	0.00
	2	1.37

Hydrolysis Results for the test item at pH 7 and 50 °C

Hydrolysis Time [hours]	Replicate	Concentration [mg/L]	Mean	Degradation [%]
0	1	1.32	1.41	-
	2	1.50
120	1	1.50	1.48	0.00
	2	1.46

Hydrolysis Results for the test item at pH 9 and 50 °C

Hydrolysis Time [hours]	Replicate	Concentration [mg/L]	Mean	Degradation [%]
0	1	1.49	1.44	-
	2	1.39
120	1	1.41	1.40	2.78
	2	1.39

Validity criteria fulfilled:

yes

Conclusions:

The test item was found to be stable in the preliminary test at pH 4, 7 and 9 at 50 °C (Table 1). Reaction rate constants and half lives could not be calculated due to the fact that the test item undergoes no significant hydrolysis. With regard to the guideline a half life of > 1 year could be assumed.

Executive summary:

Hydrolysis as a function of pH was determined according to OECD Guideline No. 111 and Council Regulation (EC) No. 440/2008, Method C.7 for the test item.

The study was conducted with test item concentrations of 1.5 mg/L in buffer solutions at pH 4, 7 and 9 at a test temperature of 50 °C (preliminary test).

Samples were taken at test start (0 hours) and test end (120 hours) and analysed via LC-MS/MS on a reversed phase column using an external standard. Buffer solutions were analysed at test start and test end and indicated no interference with the test item. The analytical method for determination of the test item was validated and tested with satisfactory results in regard to linearity, accuracy, precision and specificity.

Degradation was calculated as the percentage loss of the test item over the time. In the preliminary test, the test item was found to be stable at pH 4, 7 and 9, respectively. No further testing was deemed necessary as less than 10 % of the applied test item was transformed after 120 hours (5 days) at each of the three pH values (Table 1). Reaction rate constants and half lives could not be calculated because the test item undergoes no significant hydrolysis. With respect to the guidelines a half life of > 1 year could be assumed for ambient temperature conditions.

Table 1:    Degradation [%] of the test item at 50 °C after 120 Hours

Hydrolysis Time [hours]	Degradation [%]
	pH 4	pH 7	pH 9
120	0.00	0.00	2.78

Description of key information

The test item was found to be stable in the preliminary test at pH 4, 7 and 9 at 50 °C (Table 1). Reaction rate constants and half lives could not be calculated due to the fact that the test item undergoes no significant hydrolysis. With regard to the guideline a half life of > 1 year could be assumed.