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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption of the test item to the solid soil phase is not expected.

Key value for chemical safety assessment

Additional information

The Koc was estimated using both models of KOCWIN v2.00 of EPI Suite v4.10. Using the Molecular Connectivity Index (MCI) which is regarded as more reliable compared to the log Kow method, the log Koc for the uncharged molecule was estimated to be 1.25 (Koc = 18 L/kg). Based on the measured log Pow of 0.83 (BASF AG, 1989, report no. BRU 89.099), the log Koc was estimated at 1.03 (Koc = 11 L/kg) using the log Kow method. Both estimates refer to the uncharged molecule (BASF SE, 2013).

However, the measured pKa of 10.39 (calculated; SPARC v4.6 database) indicates that cyclopentylamine (CAS 1003 -03 -8) 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 2.17 (Koc = 149 L/kg) following the method of Franco & Trapp (2008, 2009, 2010) and using the pKa of 10.39 and the measured log Kow for the uncharged molecule of 0.83. 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.

In conclusion, the log Koc of the charged molecule is expected to be < 3 (pH 7, 25 °C). Therefore, significant adsorption of the substance to the solid soil phase is unlikely.