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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
supporting 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:
See attached QMRF/QPRF
Principles of method if other than guideline:
The model is the existing SRC model KOWWIN v 1.68, which is a component of the EPI Suite v4.11 (EPIWIN 2012 and Meylan 1995). It is based on fragment values. That is, the chemical structure is broken down into its constituent functional groups, and the contribution of each group toward the overall octanol-water partition coefficient is calculated.
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
>= 6.58 - <= 9.11
Temp.:
20 °C
Remarks on result:
other: The individual constituents of the substance have predicted log Kow values of 6.58 - 9.11

Table 1: Predicted log Kowfor the individual constituents for linear and branched alkanes of C14-C16.

Carbon

Number

CH3

CH2

branched

 

SMILEs1

log Kow2

13

2

11

0

CCCCCCCCCCCCC

6.73

13

3

9

1

CCCCCC(C)CCCCCC

6.65

13

4

7

2

CCC(CC(C)C)CCCCCC

6.58

14

2

12

0

CCCCCCCCCCCCCC

7.22

14

3

10

1

CCCCCC(C)CCCCCCC

7.14

14

4

8

2

CCC(CC(C)C)CCCCCCC

7.07

15

2

13

0

CCCCCCCCCCCCCCC

7.71

15

3

11

1

CCCCCC(C)CCCCCCCC

7.63

15

4

9

2

CCC(CC(C)C)CCCCCCCC

7.56

16

2

14

0

CCCCCCCCCCCCCCCC

8.20

16

3

12

1

CCCCCC(C)CCCCCCCCC

8.13

16

4

10

2

CCC(CC(C)C)CCCCCCCCC

8.05

17

4

11

2

CCC(CC(C)C)CCCCCCCCCC

8.54

17

3

13

1

CCCCCC(C)CCCCCCCCCC

8.62

17

4

11

2

CCC(CC(C)C)CCCCCCCCCC

8.54

 18  3  14  1  CCCCCC(C)CCCCCCCCCCC  9.11

 

1Only a single possible isomer is represented for branched compounds

2The log Kow is not dependent of the location of any branch point in the molecule

Conclusions:
The individual constituent of the substance has a predicted log Kow of 6.58 - 9.11 using a validated QSAR estimation method. The result is considered to be reliable.
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental Starting Date: 04 December 2013 Experimental Completion Date: 11 March 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
6.85 - 7.2
Temp.:
35 °C
pH:
7.33
Remarks on result:
other: 6.85 to >7.2

 

Results

Preliminary estimate

Approximate solubility in n-octanol: greater than 1.00 x 105 mg/L

Approximate solubility in water:       less than 9.90 mg/L

Approximate partition coefficient:    greater than 1.01 x 104 (log Pow > 4.01)

Definitive Test

Please see Attachment 2 for the Typical Chromatography.

Calibration

 

The dead time and the retention times, capacity factors (k′) and log10Pow values for the reference standards are shown in the following tables:

 

Table 3.10

 

Dead Time

Retention Time (min)

Mean Retention Time (min)

Injection 1

Injection 2

Formamide

1.684

1.684

1.684

 

Table 3.11

 

Standard

Retention Time (min)

Mean Retention Time (min)

Capacity Factor (k′)

log10k

log10Pow

Injection 1

Injection 2

Hexane

4.655

4.657

4.656

1.76

0.247

3.90

Heptane

5.325

5.328

5.327

2.16

0.335

4.66

Octane

6.134

6.139

6.137

2.64

0.422

5.18

Nonane

7.132

7.135

7.134

3.24

0.510

5.65

Dodecane

11.594

11.599

11.597

5.89

0.770

6.10

Tetradecane

16.349

16.358

16.354

8.71

0.940

7.20

Partition coefficient of sample

 

The retention times, capacity factors and log10Pow values determined for the sample are shown in the following table:

 

Table 3.12

 

Peak

Injection

Retention Time (mins)

Capacity Factor (k′)

log10k′

log10Pow

Mean log10Pow

Pow

Mean Area%

1

1

13.710

7.14

0.854

6.85

6.85

7.14 x 106

9.94

2

13.715

7.14

0.854

6.85

2

1

14.987

7.90

0.898

7.05

7.04

1.11 x 107

18.2

2

14.929

7.87

0.896

7.04

3

1

16.319

8.69

0.939

>7.20

>7.20

>1.58 x 107

26.3

2

16.333

8.70

0.939

>7.20

4

1

17.445

9.36

0.971

>7.20

>7.20

>1.58 x 107

26.9

2

17.451

9.36

0.971

>7.20

5

1

19.408

10.52

1.022

>7.20

>7.20

>1.58 x 107

14.6

2

19.418

10.53

1.022

>7.20

6

1

20.647

11.26

1.052

>7.20

>7.20

>1.58 x 107

4.15

2

20.661

11.27

1.052

>7.20

 

Overall log10Pow:        6.85 to > 7.20

Partition coefficient:  7.14 x 106 to > 1.58 x 107

 

Conclusions:
Please see the Executive Summary for the Conclusion.
Executive summary:

The determination was carried out using the HPLC Method designed to be compatible with Method A8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

 

The test system consisted of a high performance liquid chromatograph with a suitable detector. A reverse phase HPLC column with a very low percentage of polar groups was used (e.g. C8, C18). The mobile phase contained at least 25% aqueous phase.

Conclusion

The partition coefficient of the test item has been determined to be in the range 7.14 x 106 to greater than 1.58 x 107 (log10 Pow  6.85 to > 7.20).

 

Description of key information

log Kow (constituents of the substance): 6.85 to >7.2 at 35°C and pH 7.3 (measured)
log Kow (constituents): 6.58 - >9 at 20°C (QSAR)

Key value for chemical safety assessment

Additional information

The log Kow of the constituents of the substance have been measured using the HPLC method in accordance with OECD 117 Test Method and in compliance with GLP. The n-octanol/water partition coefficients of the constituents were determined to be in the range 7.14 x 106 to >1.58 x 107 (log10 Pow  6.85 to >7.2) at 35°C and pH 7.3. The study was considered to be reliable but the results are not useful for chemical safety assessment.

As supporting information, log Kow for individual constituents of Hydrocarbons, C14-C16, n-alkanes, isoalkanes, <2% aromatics have been predicted using a separately validated QSAR estimation method. The prediction method uses a fragment method and log Kow increases with increasing carbon number. The individual constituents of the substance have predicted log Kow values in the range 6.58 - >9 at 20°C.