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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Significant long-term adsorption to solid soil phase is not expected.

Key value for chemical safety assessment

Koc at 20 °C:
84

Additional information

A calculated logKoc of 1.66 refering to the uncharged molecule (pKa value: 11.09) is available (BASF AG, SRC PCKOC v1.66, 2008). The pKa value indicates that the molecule will exist primarily as a cation in the environment and cations generally adsorb stronger to soils containing organic carbon and clay than their neutral counterparts. Hence, the PCKOC-model may underestimate adsorption to organic carbon since it does not consider the ionic structure of the molecule. Under environmental conditions (pH from 5 to 9) the test substance is almost completely present in its charged form (as calculated by the formula % ionised = 100/(1+10(pKa - pH)): 99% at a pH of 9, 100% at lower pH values). In a calculation conducted according to a publication by Franco & Trapp, 2008 using the parameters pKa = 11.09 and log Pow = 0.58 a log Koc value of 1.92 (Koc 84, pH 7.0) was determined.

In accordance with column 2 of REACH Annexes VIII and IX, the study does not need to be conducted if based on the physicochemical properties the substance can be expected to have a low potential for adsorption (e.g. the substance has a low octanol water partition coefficient), or the substance and its relevant degradation products decompose rapidly. Diethylamine (CAS 109-89-7) has a log Kow of 0.58 (weight of evidence, IUCLID Ch. 4.7) and is readily biodegradable according to OECD criteria (MITI, 1992; BASF AG, 1990).