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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
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:
Estimation of Kow was made using REACH guidance recommended (R.7.1-24) softwares such as KOWWIN, SPARC and ACD.
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6, May/July 2008
Principles of method if other than guideline:
As an experimental determination of the partition coefficient n-octanol/water using OECD 107 or 117 was not applicable due to limits of the analytical detection method, the paltition coefficient noctanol/water was assessed by estimation. It was estimated through KOWWIN, SPARC and ACD computational methods recommended in chapter R.7a, in: Guidance on information requirements and chemical safety assessment (table R.7.1-24).
Type of method:
other: computational methods using programs KOWWIN and SPARC as stated in table R.7.1-24 of the REACH guidance document
Partition coefficient type:
octanol-water
Analytical method:
other: not applicable
Key result
Type:
log Pow
Partition coefficient:
ca. 3.05 - ca. 8.23
Remarks on result:
other: Mean value of logPow estimated using KOWWIN, SPARC and/or ACD/LogP for octanoic acid, stearic acid and oleic acid, representing free fatty acids (substance class)
Key result
Type:
log Pow
Partition coefficient:
ca. 9.3 - ca. 24.2
Remarks on result:
other: Mean value of logPow estimated using KOWWIN, SPARC and/or ACD/LogP for the triglyceride of octanoic acid, stearic acid and oleic acid representing glycerides of fatty acids (substance class)
Key result
Type:
log Pow
Partition coefficient:
ca. 3.05 - ca. 24.2
Remarks on result:
other: Mean value of logPow for the individual constituents estimated using KOWWIN, SPARC and/or ACD LogP
Key result
Type:
log Pow
Partition coefficient:
> 6
Remarks on result:
other: Mean value of LogPow for ≥90% of the individual constituents of the test substance
Details on results:
See below Table for the estimations of the range of log Kow values for the individual substances of ‘soaps, stocks, vegetable oil, acidulated’ as well as the attachment under the 'attached background material' for the details of the estimated results from EPISuite.

As per this table, the different QSAR models resulted in similar estimation values. The lower and upper limit of the average Log Kow values for individual constituents were:
Fatty acids: Estimations ranged from 3.05-8.23
Glycerides: Estimations ranged from 9.3-24.2
Based on the above estimations, the lower and upper limit of the Log Kow values for the test substance was considered to be 3 and 24. However, considering ≥90 % of the individual constituents of the test substance, the overall log Kow of the test substance is considered to approximately exceed 6 and thus is considered to partition more into the lipophilic phase (represented by octanol).

See the PDF under 'attached background material' for the details of the estimated results from EPISuite:

The ACD/LogP estimations for the individual constituents can be retrieved through ChemSpider (http://www.chemspider.com/) or via the below specific webpages:
Octanoic acid: http://www.chemspider.com/Chemical-Structure.370.html?rid=26453fc3-0805-4fdd-8a4f-f781654f3f38
Stearic acid: http://www.chemspider.com/Chemical-Structure.5091.html?rid=c2801bfa-cf09-4078-9ecb-0840ca926f37
Oleic acid: http://www.chemspider.com/Chemical-Structure.393217.html?rid=80b792b4-b392-45b5-9eae-bddbe6ff4b75
Trioctanoin: http://www.chemspider.com/Chemical-Structure.10393.html?rid=26d83678-56e8-4306-8d84-2d885fabe6b9
Tristearin: http://www.chemspider.com/Chemical-Structure.10673.html?rid=a1968044-641c-49fa-89c9-eed205a883f8
Triolein: http://www.chemspider.com/Chemical-Structure.4593733.html?rid=83eb9bd2-2928-4c53-b08a-5b4c78e703d4

As the test substance is composed of a number of different substances from different classes, a further statistical evaluation or the calculation of a weighted log Kow value is not considered meaningful.

Summary of the results from different QSAR models:

Substance

Measured or Experimental

KOWWIN v.168

SPARC

ACD/LogP (via ChemSpider)

Average

Log Kow ranges

C8 fatty acid

3.05

3.03

 

2.9

3.0

3.05-5-8.23

C18 fatty acid

8.23

7.94

7.96

8.22

8.0

C18-unsatd. fatty acid (oleic acid)

7.64

7.73

 

7.7

7.7

C8 triglyceride

 

9.20

 

9.33

9.3

9.3-24.2

C18 triglyceride

 

23.94

23.37

25.27

24.2

C18-unsatd. Triglyceride (triolein)

 

23.29

 

23.71

23.5

Conclusions:
Based on the modelling results for >90 % of the individual constituents of the test substance, the overall log Kow of the test substance is considered to exceed 6 and thus is considered to partition more into the lipophilic phase (represented by octanol).
Executive summary:

The partition coefficient of ‘soaps, stocks, vegetable oil, acidulated’ was estimated through computational methods recommended in chapter R.7a, in: Guidance on information requirements and chemical safety assessment. The estimations were performed with the programs KOWWIN, SPARC and/or ACD as stated in table R.7.1-24 of the REACH guidance document.

As the test substance is a mixture of different constituents (i.e. glycerides of fatty acids and, fatty acids) the log Kow was determined for representative substances of each class present >10% to represent the lower and upperlimit of the test substance. Hence, the log Kow estimations were carried out for octanoic acid, stearic acid and oleic acid representing fatty acids and trioctanoin, tristearin and triolein representing glycerides of fatty acids.

Since the estimated values via the different QSAR models did not show large variations, an average log Kow was determined for the individual constituents. The average estimated log Kow values using the different QSAR models ranged between 3.05-8.23 for the fatty acids and between 9.3 -24.2 for the glycerides of fatty acids. The values for the fatty acids were based on actual experimental values. Therefore, the lower and upper limit of log Kow of the individual constituents was estimated to be approx. 3 and 24 respectively.

Overall, based on the modelling results for ≥90% of the individual constituents of the test substance, the overall log Kow of the test substance is considered to approximately exceed 6 and thus is considered to partition more into the lipophilic phase (represented by octanol).

Description of key information

The partition coefficient of ‘Soaps, stocks, vegetable oil, acidulated’ was estimated through computational methods recommended in chapter R.7a, in: Guidance on information requirements and chemical safety assessment. The estimations were performed with the programs KOWWIN, SPARC and/or ACD as stated in table R.7.1 -24 of the REACH guidance document.

Key value for chemical safety assessment

Log Kow (Log Pow):
6
at the temperature of:
25 °C

Additional information

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