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Physical & Chemical properties

Partition coefficient

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Reference
Endpoint:
partition coefficient
Remarks:
Octanol/Water partition as a function of pH (LogD)
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
23 Mar 2017
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Justification for type of information:
1. SOFTWARE
ARChem SPARC. version 4.6

2. MODEL
LogD

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables".

5. APPLICABILITY DOMAIN
See information provided in "Any other information of materials and methods incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Deviations:
not applicable
Principles of method if other than guideline:
Calculation based on SPARC version v4.6, "LogD" model

- Software tool(s) used including version: SPARC v4.6
- Model(s) used: LogD
SPARC calculates the liquid-liquid distribution coefficient as a function of pH. The calculation method conbines the output of two other models: the octanol / water partition coefficient (LogPow) model included in the "Properties" section, and the pKa (dissociation constant) model.
The LogPow is obtained by combining the calculated activities at infinite dilution of the molecular species of interest in each of the liquid phases, as described by Hilal et al. 2004.
For the pka calculation, SPARC breaks the molecule into two type of functional units: the reaction center (with known chemical properties) and the perturber. pKa of the reaction center is adjusted for the molecule in question using the mechanistic perturbation models.
For the complete method's description see field 'Any other information on materials and methods incl. tables'.
The datasets used for the LogPow and pKa models development and for the external validation are described in the field 'Any other information on materials and methods incl. tables'.
- Model description: see field 'Any other information on materials and methods incl. tables'.
- Justification of QSAR prediction: see field 'Justification for type of information' and 'overall remarks'.
GLP compliance:
no
Type of method:
other: Log D using SPARC
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
SMILES code:
[NH4+].FC(F)(C(F)(F)C([O-])=O)C(F)(F)C(F)(F)C(F)(F)F
Key result
Type:
log Pow
Partition coefficient:
2.06
pH:
4
Remarks on result:
other: Log D (pH 4); partition coefficient of partly ionized substance at pH 4 (calculated using SPARC).
Key result
Type:
log Pow
Partition coefficient:
2.047
pH:
7
Remarks on result:
other: Log D (pH 7); partition coefficient of partly ionized substance at pH 7 (calculated using SPARC).
Key result
Type:
log Pow
Partition coefficient:
2.047
pH:
9
Remarks on result:
other: Log D (pH 9); partition coefficient of partly ionized substance at pH 9 (calculated using SPARC).
Details on results:
The reported SPARC results for Log D vs. pH, for the PFHx/PFHxA equilibrium, are summarized separately.

Description of key information

The average of measured log Pow value is 1.5 for the relevant (dissociated form, pH=7.4), using OECD 117 (HPLC Method) at 25 °C.         

Key value for chemical safety assessment

Log Kow (Log Pow):
1.5
at the temperature of:
25 °C

Additional information

Note 1: The key measured value (Log Kow = 1.5) is for the more relevant dissocated form at pH = 7.4. At pH 2.0, the acid form is present and has a Log Kow measured value of 2.1 (at 25 deg C).

Note 2: Supporting data is obtained by SPARC calculations: Log D (pH 7) = 2.05 and Log D (pH 9) = 2.05 values are rounded from 2.047. The distribution coefficient, Log D, was determined at pH 4, 7 and 9 using a SPARC calculation, as summarized below.

Log D (pH 4) = 2.06

Log D (pH 7) = 2.05

Log D (pH 9) = 2.05