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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Mobile in soil, low adsorption potential acting as kation

Key value for chemical safety assessment

Koc at 20 °C:

Additional information

The relevant part of the submission item Guanidine carbonate is the Guanidine (CAS 113-00-8) as discussed in the section on Environmental fate and pathways above. It is present as the Guanidinium kation (see section Dissociation constant). The carbonate, is considered negligible for the environmental assessment and disregarded in the following discussion

Using a structure estimation method based on molecular connectivity indices (Meylan et al 1992), the Koc of Guanidine can be estimated to be ca. 20 (HSDB 2008). According to classification schemes, this estimated Koc value suggests that Guanidine is expected to have “very high mobility” in soils (McCall et al 1981, Swann et al 1983) or falls into the “Mobile” class (Hollis 1991).

The pKa of Guanidine is 12.5 (O'Neil 2006), indicating that this compound will exist almost entirely as a kation in the environment (HSDB 2008). Kations generally adsorb more strongly to soils containing organic carbon and clay than neutral species (Doucette 2000). Guanidine may thus have greater adsorption and less mobility than its estimated Koc value indicates.

In conclusion the “Mobile” class should be assigned.

  • Doucette WJ (2000). pp. 141-188 In Handbook of Property Estimation Methods for Chemicals. Boethling RS, Mackay D, eds. Boca Raton, FL, U.S.A.: Lewis Publ
  • Hollis JM (1991). Mapping the vulnerability of aquifers and surface waters to pesticide contamination at the national/regional scale. Pesticides in Soils and Water: Current Perspectives (A Walker Ed), BCPC Monograph 47:165-74
  • HSDB Hazardous Substances Databank (2008). GUANIDINE, CASRN: 113-00-8, Number: 7603. Last Revision Date: 2008-08 -26, Last Review Date: Reviewed by SRP 5/8/2008, Update History: Complete Update on 2008 -08-26, 38 fields added/edited/deleted, Created 20071213
  • McCall PJ, Laskowski DA, Swann RL, Dishburger HJ (1981). Measurement of sorption coefficients of organic chemicals and their use, in environmental fate analysis IN Test Protocols for Environmental Fate and Movement of Toxicants. Proceedings of AOAC Symposium, AOAC, Washington DC, U.S.A:94-109
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