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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:
2-11 Mar 2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
GLP compliance:
no
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
> 6.44
Temp.:
25 °C
pH:
>= 5.18 - <= 5.29

The concentration of the test item in the aqueous and 1 -octanol phase was determined after 68, 70, 72 and 74 hours, ensuring that an equilibrium concentration was established in both phases. At each test time, three different test solutions were analysed. The results are given in the table:

Time (h)

Octanol phases, test mixture (mg/g)

Aqueous phases, test mixture (µg/g)

1

2

3

1

2

3

68

32.40

32.21

32.60

< 0.012

 < 0.012

 < 0.012

70

33.32

32.56

33.09

< 0.012

< 0.012

< 0.012

72

33.33

32.69

32.94

< 0.012

< 0.012

< 0.012

74

33.21

32.79

32.71

< 0.012

< 0.012

< 0.012

For each time interval the Pow and log Pow values are calculated for each test mixture. The results are summarized in the table:

Time (h)

Calculated Pow values, test mixture no.

Calculated log Pow values, test mixture no.

1

2

3

1

2

3

68

>2700000

>2684000

>2717000

>6.431

>6.429

>6.434

70

>2777000

>2713000

>2758000

>6.444

>6.434

>6.441

72

>2778000

>2724000

>2745000

>6.444

>6.435

>6.439

74

>2768000

>2733000

>2726000

>6.442

>6.437

>6.435

pH values of aqueous phases were 5.24, 5.29 and 5.18, for mixtures 1, 2 and 3, respectively.

Endpoint:
partition coefficient
Type of information:
mixture rules calculation
Adequacy of study:
supporting study
Study period:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Calculation from experimentally derived Koc data using an equation from the 2003 EU Technical Guidance Document on Risk Assessment Part III, Chapter 4, Section 4.3
Qualifier:
according to guideline
Guideline:
other: 2003 EU Technical Guidance Document on Risk Assessment Part III, Chapter 4, Section 4.3, p. 26
Deviations:
no
Principles of method if other than guideline:
Log Kow was calculated using an equation derived from experimentally determined Koc values for analogue structures using the 2003 TGD equation for predominantly hydrophobic substances.
GLP compliance:
no
Type of method:
other: calculation from log Koc values
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
6.84
Remarks on result:
other: weight-averaged value
Details on results:
Weight-averaged log Koc of the whole substance based on normalized composition: 5.64.
This value was used in the rearranged TDG equation mentioned above resulting in a log Pow value of 6.84.
Endpoint:
partition coefficient
Type of information:
mixture rules calculation
Adequacy of study:
supporting study
Study period:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Justification for type of information:
QSAR prediction with KOWWIN v1.68
Principles of method if other than guideline:
The calculations were performed for the linear free alcohols and ethoxylated alcohols (AE) with ethoxylation degree of 1 and 3, respectively, using KOWWIN v1.68, Estimation Programs Interface Suite™ for Microsoft® Windows v4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.
In order to derive a single value for risk assessment, the various calculated vapour pressure values were weight-averaged using normalized values for composition (linear free alcohols and C18' AE).
GLP compliance:
no
Type of method:
other: QSAR
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
7.11
Remarks on result:
other: weight-averaged value

QSAR result; pH and temperature are not reported. For detailed description of the model and its applicability, see "Any other information on materials and methods incl. tables".

Individual calculated values for log Pow (taken from the EPIsuite v 4.11 report, 2016)

structure

SMILES notation used in calculation

EPI log Pow calc.

Alcohol, C18

CCCCCCCCC=CCCCCCCCCO

7.50

Alcohol ethoxylate, C18, 1 EO

CCCCCCCCC=CCCCCCCCCOCCO

7.23

Alcohol ethoxylate, C18, 3 EO

CCCCCCCCC=CCCCCCCCCOCCOCCOCCO

6.68

 

Mean calculated values for log Pow for each ‘sub’-group

 

Mean log Pow calc.

Free alcohol

7.50

C18-EO (avg of 1EO and 3EO)

6.96

 

Result:

Weight-averaged log Pow of the whole substance based on normalized composition: 7.11

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
method not fully appropriate for this type of substances
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
GLP compliance:
no
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
7.5
Temp.:
25 °C
Remarks on result:
other: no information about pH
Details on results:
The stated result is a weighted average. Refer to table for full range of results.

Experimental results:

  RT [min]1 K log K  log Pow Area [%] log Pow contribute2
 Peak 1  7.65    3.78   0.58   6.85   1.8   0.12
 Peak 2  8.66    4.41   0.64   7.15   7.8   0.56
 Peak 3  9.69    5.05   0.70   7.42  28.5  2.12
 Peak 4 10.65   5.66  0.75  7.65  61.9  4.73
Weighted average log Pow: 7.5 

1 = Average of two injections

2 = Area[%] * log Pow

Conclusions:
Substance: log Pow = 7.5 at 25°C
Executive summary:

The Pow of (Z)-9-Octadecen-1-ol ethoxylated was determined according to OECD 117 method.

The log Pow versus logK of the reference substances was plotted (R² = 0.9792; y = 4.5517x + 0.9792). The resulting equation was used to calculate the log Pow of the test substance: 7.5 at 25°C. pH of the water phase was not determined.

Description of key information

Key study:

log Pow - experimental result: > 6.44 at 25 °C (OECD 123, slow-stirring method)

Supporting studies:

log Pow – experimental value: 7.50 (OECD 117, HPLC method)
log Pow - calculated from weight-averaged log Koc value: 6.84 (calculation based on 2003 EU TGD)
log Pow - calculated using KOWWIN v1.68 (weight-averaged value): 7.11 (EPISuite v4.11)

Key value for chemical safety assessment

Log Kow (Log Pow):
7.15

Additional information

Application of the most appropriate method for this type of substances, i.e. slow-stirring method (OECD Guideline 123) resulted in the log Pow estimation of > 6.44. In order to obtain a precise value for chemical safety assessment, supporting results were taken into account (average of 3 values: experimental 7.5; calculated 6.84 and 7.11). They all are compliant with the key result of > 6.44.

The log Pow of 7.5 for the substance was determined experimentally using the HPLC method according to OECD Guideline 117. This method has only limited validity for this type of compounds.

The following types of calculations were applied:

1. based on weight-averaged log Koc values using the TGD equation for predominantly hydrophobic substances: log Koc = 0.81 log Pow + 0.10 thus log Pow = (log Koc – 0.10)/0.81 (2003 EU Technical Guidance Document on Risk Assessment Part III, Chapter 4, Section 4.3, pp 24 – 27). Result: 6.84.

2. based on EPIsuite v 4.10, KOWWIN v 1.68 log Pow values for (possible) individual constituents of the substance; a weighting based on normalized composition was applied to derive a log Pow value for the whole substance. Result: 7.11.