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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to the solid soil phase is not expected.

Key value for chemical safety assessment

Additional information

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. 2-[2-(3-aminopropoxy)ethoxy]ethanol (CAS 112-33-4) has a log Kow of -1.47 (measured; BASF SE, 2013).

The adsorption potential was estimated for 2 -[2 -(3 -aminopropoxy)ethoxy]ethanol (CAS 112 -33 -4) using the MCI and the Kow methods of the PCKOCWIN v2.00 module from SRC EPI Suite v4.10. These estimates are representative for uncharged molecules. The substance ionises in aqueous solutions, therefore the adsorption coefficient was calculated according to Franco & Trapp (2008), Franco et al. (2009) and Franco (2010) to correct for the charged molecule at pH 5, 7 and 8. The Koc values are listed below.

 

Uncharged molecule:

- MCI method: Koc = 10; log Koc = 0.15

- Kow method: Koc = 0.24; log Koc = -0.6

Charged molecule:

- Franco & Trapp, (2008, 2009, 2010):

pH 5 to 8: Koc = 12; log Koc = 1.07

The pKa of 10.2 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 KOCWIN 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 8) the test substance is almost completely present in its charged form (as calculated by the formula% ionised = 100/(1+10(pKa - pH)): 100% at pH 5 to 8).Regarding the charged molecule, at pH 7 the log Koc was estimated to be 1.07 (Koc = 12 L/kg) following the method of Franco & Trapp (2008, 2009, 2010) and using the pKa of 10.2 and the measured log Kow for the uncharged molecule of -1.47. The correction was performed for pH 5, 7, and 8, which represents 98% of the European soils. The value at pH 7 will be used as key value, i.e. for PEC and PNEC calculations.

Adsorption to the solid soil phase is not expected.