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The adsorption/desorption behaviour of N-[2-(piperazin-1-yl) ethyl]C18-insaturated-alkylamide on soils was evaluated in a study performed in accordance with OECD testing guideline 106 and GLP requirements. This test was performed for the C18 carbon chain components with 1, 2 and 3 double bonds that represent the main components of the test substance. At the test conditions the adsorption coefficient Kd was found to be in the range of 2300 to 4600 (cm3/g) for the C18:1 component, 1600 to 3300 for the C18:2 component and 1000 to 1900 for the C18:3 component in the different soils tested. Consequently, the test substance is considered to be strongly sorptive to soil/sediment particles.

Due to the cationic surface-active properties will N-[2-(piperazin-1-yl) ethyl]C18-insaturated-alkylamide adsorb strongly onto the solid phase of soil and sediments. The substance can adsorb both onto the organic fraction and, dependent on the chemical composition, onto the surface of the mineral phase, where sodium and potassium ions can be exchanged against the alkyl ammonium ion. The determination of a Koc from log Kow is not opportune, because the common equations for Koc derivation are not valid for both ionic and surface active substances. Therefore not the Koc values should be evaluated but the Kd values. Therefore the Kd values are reported and not the Koc values. Kd values range from 1000 to 4600 L/kg. As for risk assessment purposes only one Kd can be used, the sorption results (Kd) of Eurosoil 4 were used (average here is 2000 L/kg) as a realistic worst-case representative.