Registration Dossier
Registration Dossier
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EC number: 223-786-9 | CAS number: 4073-98-7
Adsorption / desorption
Administrative data
Link to relevant study record(s)
Description of key information
Adsorption to solid soil phase cannot be excluded at pH 5 - 8 (logKoc > 3.0).
Key value for chemical safety assessment
Additional information
The adsorption potential was estimated for 4,4'-methylenebis(2,6-xylidine) (CAS 4073 -98 -7) using the MCI and the Kow methods of the KOCWIN v2.00 module from SRC EPI Suite v4.10. These estimates are representative for uncharged molecules. Based on a calculated macroscopic pKa of 4.87, at environmentally relevant conditions the molecule is expected to be predominantly uncharged (55% at pH 5 and 99% at pH 7). The adsorption coefficient was calculated according to Franco & Trapp (2008) to correct for the charged molecule at pH 5. The Koc values are listed below.
Uncharged molecule:
- MCI method: Koc = 15270; log Koc = 4.1839 (referring to pH conditions of > 7)
- Kow method: Koc = 1991; log Koc = 3.2991
Charged molecule:
- Franco & Trapp, 2008:
pH 5: Koc = 1459; log Koc = 3.16
Based on these results and the corrections for the charged molecule at pH 5, adsorption to the solid soil phase cannot be excluded at pH 5 - 8 (logKoc > 3.0). These findings are supported by the results of the Zahn-Wellens-Test (BASF, 1981). In this test a rapid decline (> 90% DOC-removal after 3 h) was found which was mainly due to adsorption to the solid phase.
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