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Partition coefficient

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Description of key information

Hydrophilic due to dissociation in body fluids and the environment 

Key value for chemical safety assessment

Log Kow (Log Pow):
at the temperature of:
20 °C

Additional information

The partition coefficient of the submission item Guanidine carbonate was determined using a shake flask method at pH 11.8 (Junghans 2009). The measured value of -1.43 is in an acceptable accordance with the estimate of -1.63 for Guanidine (CAS 113-00-8), calculated by KowWin v1.68 (software form the US EPA EPI Suite 4.10). The submission item exists in body fluids and under environmental conditions solely dissociated in the Guanidinium kation and the (hydro)carbonate species, which were not further regarded as they are non-toxic and omnipresent (see discussion in the section on Environmental fate and pathways). The uncharged guanidine species appears from ca. pH 10 on (estimated using MarvinSketch 5.3.6, calculating pKa to 12.55, and in good accordance with the experimental pKa value ca. 12.5 presented in the section on Dissociation constant) and reaches at pH 11.8 ca. 15 %. Accordingly the measurement of Junghans (2009) should be regarded as Distribution coefficient at pH 11.8 (Log D) and represents a higher value as the actual Log Kow, which should be measured using the uncharged species.

Data from other Guanidine compounds are available. Guanidine hydrochloride (CAS 50-01-1), which is acidic in aquatic solution, is assumed to be nonetheless comparable as it produces the dissociated Guanidine/Guanidinium kation species (see dissociation constant discussion). The experimental value of ≤-1.7 is reported in the IUCLID Dataset 2000 (EC 2000) referring to RCC-NOTOX (1988a). In a study performed by RCC-NOTOX (1988) the partition coefficient (n-octanol/water) for Guanidine Nitrate, which is neutral in watery solution, was determined to be <0.02 at 20 ± 1 °C, which gives a Log Kow of <-1.70. The study was performed according to OECD TG 107 (1981).

In result the submission item Guanidine carbonate is highly hydrophilic and the actual Log Kow is assumed to be lower than the experimental result of <-1.43 reported from Junghans (2009), as the study shows methodological deficiencies. In comparison with more reliable experimental data from other Guanidine compounds a correction to the QSPR calculated Guanidine value of -1.63 for assessment seems justified.

  • EC European Commission ECB European Chemicals Bureau (2000). IUCLID Dataset, Existing Chemical Substance ID: 593–85–1, CAS No. 593–85–1, EINECS Name diguanidinium carbonate, EINECS No. 209–813–7, Molecular Weight 180.17, Molecular Formula CH5N3.1/2CH2O3. Creation date: 18–FEB–2000. CD-ROM edition. 17 p. Available from the Database Query page at: as of May 4, 2012.
  • 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
  • RCC-NOTOX (1988a). Determination of the partition coefficient of Guanidine hydrochloride, Study No. 0917/C608, October 1988
  • RCC-NOTOX (1988b). Determination of the partition coefficient of Guanidine nitrate. RCC NOTOX B.V., Hambakenwetering 7, 5231 DD s-Hertogenbosch, The Netherlands. Study No. 0918/C 609
  • US EPA United States Environmental Protection Agency (2011). Estimation Program Interface (EPI) Suite. Ver.4.10. October, 2011. Available from, as of April 23, 2012:

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