Amides, C12-18, N-[3-(dimethylamino)propyl]

Adsorption / desorption

Description of key information

Kd of Amides, C18-unsatd., N-[3-(dimethylamine)propyl] was found to be in the range of 2500 to 4500 L/kg in the different soils tested. Consequently, with an average of 3300 L/kg, the test substance is considered to be strongly sorptive to soil/sediment particles. The experimental results obtained in this test can be taken as representative for N-[3-(dimethylamino)propyl]-C12-18(even numbered)-alkylamide.

The sorption data (Kd values) should be used as such and not normalized to the OC content of the resp. soils used as sorption is mainly based on ionic interaction and to a much lesser extend to hydrophobic interaction. (Droge & Goss, 2013 Development and Evaluation of a New Sorption Model for Organic

Cations in Soil: Contributions from Organic Matter and Clay Minerals)

Key value for chemical safety assessment

Other adsorption coefficients

Type:

log Kp (solids-water in soil)

Value in L/kg:

3.518

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in sediment)

Value in L/kg:

3.518

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in suspended matter)

Value in L/kg:

3.82

at the temperature of:

20 °C

Additional information

The adsorption/desorption behaviour of Amides, C18-unsatd., N-[3-(dimethylamine)propyl] on soils was evaluated in a study performed in accordance with OECD testing guideline 106 and GLP requirements. At the test conditions the adsorption coefficient Kd was found to be in the range of 2500 to 4500 L/kg in the different soils tested. Consequently, with an average of 3300 L/kg, the test substance is considered to be strongly sorptive to soil/sediment particles.

The amines in the test substance will to a large extent be protonated under ambient conditions and will interact with the negative surface of mineral particles or with negative charges of humic substances. The ionic interactions play a more important role than hydrophobic partitioning with organic matter. The log Koc is therefore considered as a poor predictor of the partitioning behaviour of cationic surfactants in the environment. The sorption test results are therefore not expressed in Koc but in their Kd. The adsorption/desorption behaviour of Amides, C18-unsatd., N-[3-(dimethylamine)propyl] on soils was evaluated in a study performed in accordance with OECD TG 106. At the test conditions the adsorption coefficient Kd was found to be in the range of 2500 to 4500 L/kg in the different soils tested. Consequently, with an average of 3300 L/kg, the test substance is considered to be strongly sorptive to soil/sediment particles. Because ionic interactions play a more important role than hydrophobic partitioning with organic matter, the influence of the chain length on the sorption behaviour is expected to be low, and these experimental results can be taken as representative for N-[3-(dimethylamino)propyl]-C12-18(even numbered)-alkylamide. Furthermore is an influence of the double bond in Amides, C18-unsatd., N-[3-(dimethylamine)propyl] onto sorption is not expected. Because there is no principal difference between soil and sediments considering the sorption properties (EU RAR primary alkyl amines, 2008) and because for cationic surfactants the degree of sorption is not related to the organic carbon content, the value for soil will also be used for sediment and suspended particles. For sludge which consists mainly of organic matter the sorption data as observed for soil are not considered to be representative. This is however not a serious problem because the removal by sorption in a waste water treatment plant will be close to what is observed in the waste water treatment simulation test i.e. < 0.02% removal.