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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to solid soil phase is not expected.

Key value for chemical safety assessment

Additional information

The adsorption potential was estimated for 1 -Ethylpiperidine (CAS 766 -09 -6) by determination of the Adsorption Coefficient (Koc) by High Performance Liquid Chromatography (HPLC) Method (BAYER MaterialScience AG 2006/006/06). The substance ionises in aqueous solutions, therefore the adsorption coefficient was calculated according to Franco & Trapp (2008, 2009, 2010) to correct for the charged molecule at pH 5, 7 and 8. The estimation for the uncharged molecules using

the MCI and the Kow methods of the KOCWIN v2.00 module from SRC EPI Suite v4.11 as well as the Koc values for the charged molecules are listed below.

- HPLC Method: Koc = 251; log Koc = 2.4

Charged molecule:

- Franco & Trapp, 2008, 2009 and 2010:

pH 5 to 7: Koc = 1041; log Koc = 3.02

pH 8: Koc = 1039; log Koc = 3.02

Uncharged molecule:

- MCI method: Koc = 102.6; log Koc = 2.01

- Kow method: Koc = 80.4; log Koc = 1.91

However, the measured pKa of 10.45 (REAXYS, 2011) indicates that the 1 -ethylpiperidine will primarily exist as a cation in the environment. Cations generally adsorb stronger to soils containing organic carbon and clay than their neutral counterparts.Regarding the charged molecule, at pH 7 the log Koc was estimated to be 3.02 (Koc = 1041 L/kg) following the method of Franco & Trapp (2008, 2009, 2010) and using the pKa of 10.45 and the calculated log Kow for the uncharged molecule of 1.89. The correction was performed for pH 5, 7, and 8, which represents 98% of the European soils.

Based on the determination of the adsorption coefficient by HPLC method (log Koc = 2.4), an adsorption to the solid soil phase is not expected.