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Physical & Chemical properties

Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02.09.2011 - 09.11.2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), 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.:
25 °C
pH:
6.1
Remarks on result:
other: estimated values: 9.5
Details on results:
The partition coefficient of the test item was estimated to be 9.5 at 25 °C.

Preliminary Visual Estimation of the n-Octanol Solubility

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

Table 1: Appearance of the test mixtures

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

Solubility in g/L

0.0114

0.0114

1

30

undissolved

-

-

0.0114

11

125

dissolved

> 1.04

0.0188

0.0302

11

60

dissolved

> 2.75

0.1778

0.2080

11

75

dissolved

> 18.9

The solubility of the test item in n-octanol was > 18.9 g/L.

The partition coefficient Pow may be estimated from the saturation concentrations in n-octanol and water by the following equation:

Pow = cs(octanol) / cs(water)

 s = saturation

The preliminary water solubility of the test item was determined to be < 4.0 mg/L. Using this information and the determined solubility of the test item in n-octanol a partition coefficient > 3.7 was estimated. Therefore, the HPLC method was used in the main test.

ln addition the program kowwin (part of Episuite) was used for calculating the log Pow of the test item. The calculated value was 9.7.

HPLC-Method

Table 2: Determination of the Dead Time t0

Dead time marker

tR in min

1. measurement

tR in min

2. measurement

tR in min mean

Formamide

2.41

2.42

2.42

 

Table 3: Calibration data f from OECD guideline 117, adopted 2004)

Calibration substance

1. Inj tR (min)

2. Inj tR (min)

mean tR (min)

k

log k

log Pow

2-Butanone

2.68

2.68

2.68

0.11

-0.96

0.3

Acetanilide

2.70

2.71

2.71

0.12

-0.92

1.0

Cinnamyl alcohol

2.86

2.87

2.87

0.19

-0.73

1.9

2,6-Dicholoro- benzonitrile

3.18

3.19

3.18

0.32

-0.50

2.6

Allyl phenyl ether

3.74

3.74

3.74

0.55

-0.26

2.9

Benzophenone

3.54

3.54

3.54

0.47

-0.33

3.2

Cumene

4.94

4.94

4.94

1.05

0.02

3.7

Diphenyl ether

4.57

4.57

4.57

0.89

-0.05

4.2

Fluoroanthene

6.83

6.84

6.84

1.83

0.26

5.1

4,4’-DDT

8.34

8.35

8.35

2.45

0.39

6.5

Regression: logPow= a + b * logk
Parameters: a = 4.32, b = 3.84, r2 = 0.9501

 

Table 4: log Pow of the test item

1. Inj. tR (min)

2. Inj. tR (min)

meantR (min)

k

logk

log Pow

Test Item

57.3

57.3

57.3

22.7

1.36

>6.5*
(9.5)**

* above the highest log Pow value of calibration substances (DDT)
**via extrapolation

Conclusions:
The partition coefficient of the test item was estimated to be 9.5 at 25 °C.
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. The solubility of the test item in water and n-octanol was preliminary determined and a partition coefficient log Pow > 3.7 was calculated. Using the HPLC method for the main test, the value found for the partition coefficients n-octanol/water was above the highest log Pow values of the calibration curve, therefore, it was determined to be >6.5. After extrapolation the log Pow for the test item was estimated to be 9.5.

Description of key information

The partition coefficient of the test item was estimated to be 9.5 at 25 °C.

Key value for chemical safety assessment

Log Kow (Log Pow):
9.5
at the temperature of:
25 °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. The solubility of the test item in water and n-octanol was preliminary determined and a partition coefficient log Pow > 3.7 was calculated. Using the HPLC method for the main test, the value found for the partition coefficients n-octanol/water was above the highest log Pow values of the calibration curve, therefore, it was determined to be >6.5. After extrapolation the log Pow for the test item was estimated to be 9.5 (reference 4.7-1).