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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:
2012-07-16 to 2012-07-25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Deviations:
no
GLP compliance:
no
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
6.5
Temp.:
20 °C
pH:
7
Details on results:
The logPow was determined to be 6.5.

Preliminary Visual Estimation of the n-Octanol Solubility

Different amounts of the test item and water were stirred at room temperature until the mixture appeared dissolved or the water solubility could be estimated to be below 10 mg/L.

 

Amount of the test item

in mg

Total volume

in mL

Appearance of mixture

9.9

100

undissolved

8.7

500

undissolved

4.6

500

undissolved

 The solubility of the test item in water was below 9.0 mg/L.

 

Preliminary Visual Estimation of the n-Octanol Solubility

Different amounts of the test item were stirred with a defined amount of n-octanol at room temperature and visually checked for any undissolved parts.

 

Amount of the) test
item

in g

Total amount of
the test item

in g

Volume n-octanol
(total volume)

in mL

Stirring
time

in min

Appearance of
mixture

0.016

0.016

5

20

dissolved

0.190

0.206

5

40

dissolved

0.395

0.601

5

55

dissolved

1.336

1.937

5

35

dissolved

 The solubility of the test item in n-octanol is higher than 387 g/L.

 With the data obtained the partition coefficient was calculated as: log Pow > 4.6. Therefore the partition coefficient n-octanol/water of the test item at room temperature was determined by the HPLC-method.

 

 

HPLC-Method

Determination of the Dead Time

 

Dead time
marker

tR in min
1. measurement

tR in min
2. measurement

tR in min
mean

Formamide

2.50

2.50

2.50

 

 

Calibration data (*from OECD guideline 117, adopted 2004)

Calibration
substance

1.lnj. tR
in min

2. Inj. tR
in min

mean tR
in min

k

log k

log Pow

2-Butanone

2.99

2.98

2.98

0.19

-0.71

0.3

Acetanilide

3.16

3.16

3.16

0.26

-0.58

1.0

Cinnamyl alcohol

3.81

3.80

3.81

0.52

-0.28

1.9

2,6-Dicholoro-
benzonitrile

4.86

4.86 1

4.86

0.94

-0.03

2.6

Allyl phenyl ether

7.04

7.04

7.04

1.82

0.26

2.9

Benzophenone

6.35

6.35

6.35

1.54

0.19

3.2

Cumene

13.0

13.1

13.1

4.22

0.63

3.7

Diphenyl ether

11.9

12,0

12.0

3.79

0.58

4.2

l-Fluoranthene

24.4

24.5

24.4

8.77

0.94

5.1

4,4' DDT

61.1

61.3

61.2

23.5

1.37

6.5

Regression: logPow = a + b logk

Parameters: a = 2.48, b = 2.78, r2 = 0.9811

log Pow of the test item

 

1. Inj. tR
in min

2. Inj. tR
in min

mean tR
in min

k

logk

log Pow

Test Item

73.7

73.7

73.7

24.5

1.45

6.5

 

 

Conclusions:
The logPow was determined to be 6.5 using the HPLC method.
Executive summary:

A study was conducted in accordance with OECD TG 117 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test substance using the HPLC method (reference 4.7 -1). Therefore 574 mg of the dead time marker were dissolved in 25 mL methanol and diluted from 0.1 mL to 1 mL with methanol / distilled water 75.25 % (v/v) and injected as single solutions twice. The calibration substances were dissolved in methanol and diluted from 0.1 mL to 1 mL with methanol / distilled water 75:25 % (v/v) and injected as single solutions twice. 8.0 mg of the test item were dissolved in 50 mL methanol and diluted from 0.1 mL to 1.75 mL with methanol / distilled water 40:60 % (v/v) and injected as single solutions twice. Retention times tR were measured and averaged and the decimal logarithms of the capacity factors k were calculated. The linear regression parameters of the relationship log Pow = f(log k) were also calculated from the data obtained with the calibration mixture and, therewith, log Pow of the test substance was determined from its measured capacity factor. The logPow of the test item was determined to be 6.5 at 25 °C.

Description of key information

The logPow was determined to be 6.5 using the HPLC method.

Key value for chemical safety assessment

Log Kow (Log Pow):
6.5
at the temperature of:
20 °C

Additional information

A study was conducted in accordance with OECD TG 117 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test substance using the HPLC method (reference 4.7 -1). Therefore 574 mg of the dead time marker were dissolved in 25 mL methanol and diluted from 0.1 mL to 1 mL with methanol / distilled water 75.25 % (v/v) and injected as single solutions twice. The calibration substances were dissolved in methanol and diluted from 0.1 mL to 1 mL with methanol / distilled water 75:25 % (v/v) and injected as single solutions twice. 8.0 mg of the test item were dissolved in 50 mL methanol and diluted from 0.1 mL to 1.75 mL with methanol / distilled water 40:60 % (v/v) and injected as single solutions twice. Retention times tR were measured and averaged and the decimal logarithms of the capacity factors k were calculated. The linear regression parameters of the relationship log Pow = f(log k) were also calculated from the data obtained with the calibration mixture and, therewith, log Pow of the test substance was determined from its measured capacity factor. The logPow of the test item was determined to be 6.5 at 25 °C.