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

Endpoint summary

Description of key information

Biodegradation

The ready biodegradability of the test item was determined with a non adapted activated sludge over a test period of 28 days in the Modified Sturm Test according to OECD 301 B.The test item was tested at a concentration of15mg/L in duplicates, corresponding to a total organic carbon content (TOC) of11.0mg C/L in the test vessels. The biodegradation of the test item was followed by titrimetric analysis of the quantity of CO₂produced by the respiration of bacteria. The degradation was stopped on day 28 by acidification of the test solutions. The last titration was made on day 29, after residual CO₂had been purged from the test solutions over a period of 24 hours. The percentage CO₂production was calculated in relation to the theoretical CO₂production (ThCO₂) of the test item. The biodegradation was calculated for each titration time.

To check the activity of the test system, sodium benzoate was used asfunctional control. The percentage degradation of the functional control reached the pass level of 60 % after 6 days and a biodegradation of 102 % after 28 days.

In the toxicity control containing both test and reference item a biodegradation of 37 % was determined within 14 days and it came to 40% after 28 days.The biodegradation of the reference item was not inhibited by the test item in the toxicity control.

The biodegradation of the the 1^st test item replicate reached the 10 % level (beginning of biodegradation) after 28 days with a biodegradation of 11 %. The 2^ndtest item m replicate did not reach the 10 % level. (8%)

The test item is classified as not readily biodegradable in the 10-d-window and after 28 days.

Hydrolysis

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. Reaction rate constants and half lives could not be calculated because the test item undergoes no significant hydrolysis.

Adsorption/desorption screening

The adsorption coefficient (K_OC) on soil and on sewage sludge was estimated using high performance liquid chromatography (HPLC) according to OECD 121 and Council Regulation (EC) No. 440/2008, Method C.19 for the test item.

The test was performed temperature controlled (19.5 – 19.7 °C) with mobile phase of 50 % acetonitrile and 50 % HPLC water. A 50 mg/L sample of the test itemHostavin 3206(impoverished of xylene)were analysed threefold via HPLC on a cyanopropyl (CN-) column with DAD-detection. Results are summarized below. Calibration was performed using six reference items for soil and six for sewage sludge with known values of log K_OC, each with a nominal concentration of 2 mg/L. Analysis of the reference items were performed once before and after analysis of test item, respectively. Dead time of the HPLC-system was determined threefold using 2 mg/L sodium nitrate.

The estimated values oflogK_OCandK_OCfor the test item:

	Soil		Sewage Sludge
Component	logKOC, soil	KOC, soil	logKOC, sewage sludge	KOC, sewage sludge
1	3.01	1.02×10^3	3.02	1.04×10^3
2	4.38	2.40×10^4	4.40^(1)	2.53×10^4^(1)
3^(1)	5.74	5.44×10^5	5.77	5.91×10^5
4^(1)	5.99	9.70×10^5	6.03	1.06×10^6
5^(1)	6.04	1.10×10^6	6.08	1.20×10^6
6^(1)	6.28	1.89×10^6	6.32	2.09×10^6
7^(1)	6.52	3.28×10^6	6.56	3.64×10^6
8^(1)	6.57	3.71×10^6	6.61	4.11×10^6
9^(1)	6.77	5.87×10^6	6.82	6.55×10^6
10^(1)	7.06	1.16×10^7	7.12	1.30×10^7

            ⁽¹⁾ Values for log K_OCand correspondingK_OCobtained here by extrapolation of calibration

According to the Mc Call classification scheme the test item with its componentsis classified aslow mobile to immobilein soil (K_OC500-2000 to >5000).