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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14th January 1993 to 18th May 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
not applicable
Remarks:
The study pre-dates the inception of the standard testing guideline, but follows the core principles of the test.
Principles of method if other than guideline:
The study pre-dates the introduction of the HPLC method. As the shake flask method
The test method does not conform to OECD 117 or OECD 108 (EU Method A.8) due to the solubility, the relevant analytical methods and the emulsification properties of the test material, which makes it unsuitable for evaluation using the above standard test methods. The study pre-dates the introduction of
Briefly the partition coefficient of the test material was estimated and volume ratios of the two solvents, 1:100, 1:50 and 1:200 octan-1-ol:water were prepared.
A stock solution of the test material in octan-1-ol saturated water was prepared and replicate aliquots of this were used to prepare the test mixtures. Experience with the test material in evaluating the water solubility indicated that the test material formed a stable emulsion. Further evaluations investigating the fat solubility of the test material indicated that in organic media, the test material was found to be miscible. These solutions were slowly stirred for approximately 40 hours at 20 °C and then allowed to separate. After separation, the pH of each aqueous phase was measured and the two component phases of each test mixture were analysed for the test material by derivatisation and HPLC.


GLP compliance:
yes
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
3.69
Temp.:
20 °C
pH:
6.4

Table 1: Results

Sample

Volume ratio

Vw

Vo

Cw

(mg/L)

Co

(mg/L)

Pow

Log Pow

Recovery

(mg)

pH

1

1:100

1000

10

4.900

550

112

2.05*

10.4

6.08

2

1000

10

0.116

583

5013

3.70

5.95

6.25

3

1:200

1000

20

0.073

161

2205

3.34

3.29

6.31

4

1000

20

0.030

220

7261

3.386

4.43

6.42

5

1:50

1000

5

0.072

497

6912

3.84

2.56

6.48

6

1000

5

0.009

388

43596

4.46*

1.95

6.45

Where Vw = Volume of water saturated with octanol

Vo = Volume of octanol saturated with water

Cw = Concentration of test material in water saturated with octanol

Co = Concentration of test material in octanol saturated with water

* Data not used in calculation

Mean Pow at VR = 1:100 = 5013

Mean Pow at VR = 1:200 = 4733

Mean Pow at VR = 1:50 = 6912

Mean Pow: 5348 ± 2316

Mean log Pow 3.69 ± 0.24

 

Conclusions:
The partition coefficent of the test material was determined to be log Pow 3.69 at 20 °C.
Executive summary:

The partition coefficient of the test material was determined in accordance with a method similar to the slow stirring method. Under the conditions of the test, the partition coefficent of the test material was determined to be log Pow 3.69 at 20 °C.

Description of key information

The partition coefficient of the test material was determined in accordance with a method similar to the slow stirring method. Under the conditions of the test, the partition coefficent of the test material was determined to be log Pow 3.69 at 20 °C.

Key value for chemical safety assessment

Log Kow (Log Pow):
3.69
at the temperature of:
20 °C

Additional information