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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental Starting Date: 05 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:
> 7.2
Temp.:
35 °C
pH:
7.33
Remarks on result:
other: Log Kow of >7.20 was determined for constituents of the substance

Results

Preliminary estimate

Approximate solubility in n-octanol: greater than 9.99 x 104 mg/L

Approximate solubility in water:       less than 11.4 mg/L

Approximate partition coefficient:    greater than 8.76 x 103 (log Pow > 3.94)

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

1.680

1.680

1.680

 

Table 3.11

 

Standard

Retention Time (min)

Mean Retention Time (min)

Capacity Factor (k)

log10k

log10Pow

Injection 1

Injection 2

Hexane

4.646

4.645

4.646

1.77

0.247

3.90

Heptane

5.314

5.313

5.314

2.16

0.335

4.66

Octane

6.122

6.119

6.121

2.64

0.422

5.18

Nonane

7.114

7.110

7.112

3.23

0.510

5.65

Dodecane

11.559

11.546

11.553

5.88

0.769

6.10

Tetradecane

16.293

16.279

16.286

8.69

0.939

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

16.197

8.64

0.937

> 7.20

> 7.20

> 1.58 x 107

3.03

2

16.194

8.64

0.936

> 7.20

2

1

17.795

9.59

0.982

> 7.20

> 7.20

> 1.58 x 107

6.36

2

18.059

9.75

0.989

> 7.20

3

1

19.304

10.49

1.021

> 7.20

> 7.20

> 1.58 x 107

9.25

2

19.318

10.50

1.021

> 7.20

4

1

20.671

11.30

1.053

> 7.20

> 7.20

> 1.58 x 107

15.9

2

20.696

11.32

1.054

> 7.20

5

1

23.038

12.71

1.104

> 7.20

> 7.20

> 1.58 x 107

15.7

2

23.050

12.72

1.104

> 7.20

6

1

24.655

13.68

1.136

> 7.20

> 7.20

> 1.58 x 107

16.8

2

24.647

13.67

1.136

> 7.20

7

1

27.451

15.34

1.186

> 7.20

> 7.20

> 1.58 x 107

13.5

2

27.428

15.33

1.185

> 7.20

8

1

29.318

16.45

1.216

> 7.20

> 7.20

> 1.58 x 107

14.3

2

29.406

16.50

1.218

> 7.20

9

1

32.619

18.42

1.265

> 7.20

> 7.20

> 1.58 x 107

3.08

2

32.883

18.57

1.269

> 7.20

10

1

35.026

19.85

1.298

> 7.20

> 7.20

> 1.58 x 107

2.16

2

35.469

20.11

1.303

> 7.20

 

Overall log10Pow:        > 7.20

Partition coefficient:  greater than 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 greater than 1.58 x 107(log10 Pow > 7.20).

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
Temp.:
20 °C
Remarks on result:
other: The individual constituents of the substance have predicted log Kow values of 6.58 - >9.0

Table 1: Predicted log Kow for the individual constituents for linear and branched alkanes of C15-C19.

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

2

15

0

CCCCCCCCCCCCCCCCC

8.69

17

3

13

1

CCCCCC(C)CCCCCCCCCC

8.62

17

4

11

2

CCC(CC(C)C)CCCCCCCCCC

8.54

18

2

16

0

CCCCCCCCCCCCCCCCCC

>9

18

3

14

1

CCCCCC(C)CCCCCCCCCCC

>9

18

4

12

2

CCC(CC(C)C)CCCCCCCCCCC

>9

19

2

17

0

CCCCCCCCCCCCCCCCCCC

>9

19

3

15

1

CCCCCC(C)CCCCCCCCCCCC

>9

19

4

13

2

CCC(CC(C)C)CCCCCCCCCCCC

>9

20

2

18

0

CCCCCCCCCCCCCCCCCCCC

>9

20

3

16

1

CCCCCC(C)CCCCCCCCCCCCC

>9

20

4

14

2

CCC(CC(C)C)CCCCCCCCCCCCC

>9

21   3  17  1  CCCCCC(C)CCCCCCCCCCCCCC  >9

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 constituents of the substance have predicted log Kow values of 6.58 - >9.0 using a validated QSAR estimation method. The result is considered to be reliable.

Description of key information

Log Kow (constituents of the substance): >7.2 at 35°C and pH 7.3 (measured).

Log Kow (constituents): 6.58 - >9.0 at 20°C (QSAR).

Key value for chemical safety assessment

Additional information

The substance is a hydrocarbon UVCB. Standard tests for this endpoint are intended for single substances and are not appropriate for this complex substance. However, this endpoint is characterised using quantitative structure property relationships for representative hydrocarbon structures that comprise the hydrocarbon blocks used to assess the environmental risk of this substance with QSAR software (see Section 13).

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 >1.58 x 107 (log10 Pow >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 values for individual constituents of Hydrocarbons, C15-C19, 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 prediction domain covers carbon chain length in the range C1-C18 carbon atom, it is therefore expected that log Kow for longer chain length (i.e. greater than C18) compounds will be greater than the predicted value