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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: See remark
Remarks:
Estimates of the adsorption coefficients were calculated using the predictive model KOCWIN, version 2.00 (September 2010) © 2000 - 2008, U.S. Environmental Protection Agency. The model uses a "fragment constant" methodology to predict log P, which is known as the Atom/Fragment Contribution (AFC) method and a series of statistically derived fragment correction factors.
Justification for type of information:
Because of the surfactant properties of the substance, determination of the partition coefficient was not possible using the HPLC method, Method A.8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 117 of the OECD Guidelines for Testing of Chemicals, 17 April 2004. Estimates of the partition coefficients were calculated using the predictive model, KOWWIN, version 1.68 (September 2010) © 2000 - 2008, U.S. Environmental Protection Agency.
Qualifier:
according to
Guideline:
other: ECHA Guidance Chapter R.6: QSARs and grouping of chemicals
Principles of method if other than guideline:
Because of the surfactant properties of the substance, determination of the partition coefficient was not possible using the HPLC method, Method A.8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 117 of the OECD Guidelines for Testing of Chemicals, 17 April 2004. Estimates of the partition coefficients were calculated using the predictive model, KOWWIN, version 1.68 (September 2010) © 2000 - 2008, U.S. Environmental Protection Agency.
GLP compliance:
no
Type of method:
other: Estimates of the partition coefficients using the predictive model KOWWIN.
Partition coefficient type:
octanol-water
Analytical method:
other: not relevant. Calculation made with model KOWWIN v1.68
Type:
log Pow
Partition coefficient:
ca. 15.48
Remarks on result:
other: Estimation made with KOWWIN v1.68
Type:
log Pow
Partition coefficient:
ca. 18.42
Remarks on result:
other: Estimation made with KOWWIN v1.68
Details on results:
The estimated partition coefficient values ranged from log Kow 15.48 to 18.42 for phosphorous acid, tri-C12 alkyl ester and phosphorous acid, tri-C14 alkyl ester, respectively. However, these values are out of the applicability domain of the model (log Kow between ca. -5 and 10) and should be considered with caution.
Conclusions:
The estimated partition coefficient values ranged from log Kow 15.48 to 18.42 for phosphorous acid, tri-C12 alkyl ester and phosphorous acid, tri-C14 alkyl ester, respectively. All fragments are covered in the training dataset and validation dataset of the model. However, the estimated partition coefficients are out of the applicability domain of the model (log Kow between ca. -5 and 8) and should be considered with caution.
Nevertheless, such high partition coefficients (log Kow > 10) indicate a reduced potential for bioaccumulation.
Executive summary:

The test item, which is made of different phosphorous acid alkyl esters, has a surface tension below 60 mN/m indicating surfactant properties. The HPLC method is not suitable for tensio-active substances or organic acids. Therefore, estimates of the partition coefficients were calculated using the predictive model KOWWIN version 1.68 (September 2010) © 2000 - 2008, U.S. Environmental Protection Agency, for the C12 and C14 esters. The estimated partition coefficient values ranged from log Kow 15.48 to 18.42 for phosphorous acid, tri-C12 alkyl ester and phosphorous acid, tri-C14 ester, respectively. These estimated partition coefficients are out of the applicability domain of the model (log Kow between ca. -5 and 8) and should be considered with caution.

Description of key information

The estimated partition coefficient values ranged from log Kow 15.48 to 18.42 for phosphorous acid, tri-C12 alkyl ester and phosphorous acid, tri-C14 ester, respectively. These estimated partition coefficients are out of the applicability domain of the model (log Kow between ca. -5 and 8) and should be considered with caution.

Key value for chemical safety assessment

Additional information