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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
In accordance with of ECHA’s endpoint specific guidance (R 7a) (dated July 2017), it states 'When no experimental data of high quality are available, or if experimental methods are known to be unreliable, valid (Q)SARs for log Kow may be used e.g. in a weight-of-evidence approach'. Full details on the partition coefficient predictions are provided in the attached QPRF and associated QMRFs.
Principles of method if other than guideline:
- Software tool(s) used including version: EPISuite v.4.11, SPARC v6.0, ALOGPS
- Model(s) used: KOWWIN v1.68, SPARC v6.0 and ALOGPS 2.1
- Model description: see fields 'Justification for non-standard information' and 'Attached justification'
- Justification of QSAR prediction: see field 'Justification for non-standard information' and 'Attached justification'
Type of method:
other: QSAR
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
>= 7.16 - <= 11.97
Temp.:
25 °C
Remarks on result:
not determinable because of methodological limitations
Remarks:
QSAR predictions reported
Details on results:
The substance is of uncertain and variable composition which cannot be measured directly due to dispersion in a base oil medium. The constituents present are assumed based on the reactants, and detected analytically only when isolated from the base oil. Example structures for such constituents are illustrated below. The Log Kow for the test item was determined for each identifiable structure using 3 QSAR models and the range of Log Kows was 7.16 to 11.97.

Table 1: Log octanol-water partition coefficient (Log KOW)

Chemical Formula

SMILES

Model

Sub-Model

Log Kow

C34H58N4O2

CCCCCCCCCC=CCCCCCCCCNC(=O)Nc2ccc(C)c(NC(=O)NC1CCCCC1)c2

EPISuite v4.11

KOWWIN v.1.67

11.24

SPARC v6.0

-

10.43

ALOGPS 2.1

ALOGPS

8.01

C47H74N8O4

CCCCCCCCCC=CCCCCCCNC(=O)Nc4ccc(C)c(NC(=O)NC1CCCCC1NC(=O)Nc3cccc(NC(=O)NC2CCCCC2)c3C)c4

EPISuite v4.11

KOWWIN v.1.67

11.97

SPARC v6.0

-

10.97

ALOGPS 2.1

ALOGPS

7.16

Log Kow  =  7.16 – 11.97

Conclusions:
The partition coefficient, Log Kow, of the test item was determined using the SPARC (v6.0), ALOGPS and KOWWIN (v1.68) QSAR models to be in the range of 7.16 – 11.97 at 25 °C.
Executive summary:

The partition coefficient, Log Kow, of the test item was determined using the SPARC (v6.0), ALOGPS and KOWWIN (v1.68) QSAR models. The substance is of uncertain and variable composition which cannot be measured directly due to dispersion in a base oil medium. The constituents present are assumed based on the reactants, and detected analytically only when isolated from the base oil and the Log Kow was determined to be in the range of 7.16 – 11.97 at 25 °C.

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
24 November 2009 - 26 November 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Version / remarks:
Adopted April 2004
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Version / remarks:
May 2008
Deviations:
no
GLP compliance:
yes (incl. certificate)
Other quality assurance:
other: Chemikaliengesetz ('Chemicals Act') der Bundesrepublik Deutschland (ChemG), Anhang 1 ('Annex 1'), 2008 and Directive 2004/10/EC of 11 February 2004 (Official Journal No. L 50/44)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
>= 2.6 - <= 2.9
Temp.:
25 °C
Details on results:
The test item is a UVCB; in the obtained chromatographic data two test item related signals were detected. Therefore two Log Pow valueswere determined for the test item under the chromatographic conditions. As the test item contains more than two components, other components probably do not elute with the used chromatographic conditions. The other components are expected to have different Log Pows.

The difference between the three measurements of the reference mixture was less than 0.1 log unit, and therefore the study is considered valid.

The linearity of the analytical method was confirmed in the log Pow range from 0.9 to 5.1;

Calibration Curve: y = 0.3540x - 0.4651; r2 = 0.976

Table 1: Capacity Factor (k') and log Pow of the 1st Test item response

 Retention Time (min)  Capacity Factor*  log k'*  log Pow2
 Test item  2.232  2.91  0.46  2.6
 Test item  2.237  2.92  0.47  2.6
 Test item  2.238  2.92  0.47  2.6
 Mean value1  2.236  2.92  0.47  2.6

* values represent rounded results calculated from the exact raw data

1 Mean value of three measurements

2 Calculated from regression data

Table 2: Capacity factor (k') and log Pow of the 2nd test item related response

 Retention Time (min)  Capacity Factor*  log k'*  log Pow2
 Test item  2.609  3.57  0.55  2.9
 Test item  2.604  3.56  0.55  2.9
 Test item  2.607  3.56  0.55  2.9
 Mean value1  2.607  3.56  0.55  2.9

* values represent rounded results calculated from the exact raw data

1Mean value of three measurements

2Calculated from regression data

Table 3: Capacity factor (k') and log Pow of the Reference Items

Item   Replicate of analysis  Retention Time1 (min)  Capacity Factor2  log k'2  Log Pow3
 Sodium Nitrate  3  0.571  n.a.  n.a.  n.a.
 Reference Items
 Aniline  3  1.084  0.9  -0.047  0.9
 Acetophenone  3  1.323  1.3  0.119  1.7
 Ally phenyl ether  3  2.481  3.3  0.524  2.9
 Benzophenone  3  2.481  3.3  0.524  3.2
 Isopropylbenzene  3  4.332  6.6  0.818  3.7
 Phenanthrene  3  9.303  15.3  1.184  4.5
 Fluoranthene  3  15.240  25.7  1.409  5.1

1Mean value of three measurements

2Values represent round results calculated from the exact raw data

3Log Pow values given in OECD Guideline No. 117

Conclusions:
The Log Pow values of the test item were determined to be 2.6 and 2.9 using the HPLC method at 25 ± 1 °C.
Executive summary:

The partition coefficient of the test item was determined in an OECD 117 and EC A.8 guideline study using a HPLC method with DAD detection. The test item was tested in a solution of 50 % methanol and 50 % pure water. The partition coefficients were calculated based on a calibration curve using 7 reference items and the test item was analysed in triplicate. Pre-tests were performed to confirm the suitability of the HPLC conditions and the reference items.

In the obtained chromatographic data two test item related signals were detected. Therefore two Log Pow were determined for the test item under the chromatographic conditions and these were 2.6 and 2.9 at 25 ± 1 °C. The test item is a UVCB and contains more than two components therefore it is likely that other components do not elute with the used chromatographic conditions. The other components are expected to have different Log Pows.

The study is a GLP compliant, guideline experimental study and is deemed reliable without restrictions for assessment of this endpoint.

Description of key information

The partition coefficient, Log Kow, of the test item was determined using the SPARC (v6.0), ALOGPS and KOWWIN (v1.68) QSAR models to be in the range of 7.16 – 11.97 at 25 °C.

Key value for chemical safety assessment

Additional information

The partition coefficient, Log Kow, of the test item was determined using the SPARC (v6.0), ALOGPS and KOWWIN (v1.68) QSAR models. The substance is of uncertain and variable composition which cannot be measured directly due to dispersion in a base oil medium. The constituents present are assumed based on the reactants, and detected analytically only when isolated from the base oil and the Log Kow was determined to be in the range of 7.16 – 11.97 at 25 °C.

In a supporting study the Log Pow was determined to be 2.6 and 2.9 at 25 ± 1 °C (Mollandin 2009). However, the structures associated with the peaks were not identified. The test item is a UVCB and contains more than two components, other components probably do not elute with the used chromatographic conditions. The other components are expected to have different Log Pows. This study is therefore used as supporting data.