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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:
19.11.2008 - 10.02.2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Deviations:
no
Qualifier:
according to
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:
6.6
Remarks on result:
other: extrapolated value: 9.8
Details on results:
The log Pow was determined to >6.5. It was extrapolated to be 9.8.

Preliminary Visual Estimation of the n-Octanol Solubility

An amount of the test item was stirred with n-octanol at room temperature.

Table 1. Appearance of the test mixture

Amount of the test item (g)

Total volume (mL)

Stirring time (min)

Appearance of mixture

Solubility (g/L)

0.18

10

120

undissolved

< 17.6

20

1005

dissolved

> 8.78

The solubility of the test item in n-octanol is between 8.78 and 17.6 g/L

Calculation of the Partition Coefficient logPow

The water solubility of the test item was estimated to be <7.52 mg/L. The partition coefficient logPow may be estimated from the saturation concentrations in n-octanol and water by the equation:

Pow = cS (octanol) / cS (water), where S = saturation

The partition coefficient was calculated as logPow >3.1.

 

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

2.69

2.69

2.69

 

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

3.04

3.05

3.04

0.13

-0.88

0.3

Acetanilide

3.02

3.03

3.03

0.13

-0.90

1.0

Cinnamyl alcohol

3.21

3.21

3.21

0.20

-0.71

1.9

2,6-Dicholoro- benzonitrile

3.76

3.76

3.76

0.40

-0.40

2.6

Allyl phenyl ether

4.36

4.36

4.36

0.62

-0.21

2.9

Benzophenone

4.12

4.12

4.12

0.53

-0.28

3.2

Cumene

5.75

5.75

5.75

1.14

0.06

3.7

Diphenyl ether

5.36

5.37

5.37

1.00

0.00

4.2

Fluoroanthene

9.97

9.96

9.97

2.71

0.43

5.1

DDT

8.96

8.96

8.96

2.33

0.37

6.5

Regression: logPow= a + b * logk
Parameters: a = 4.08, b = 3.72, r2 = 0.9177

Table 4. log Pow of the test item

 

1. Inj. tR (min)

2. Inj. tR (min)

meantR (min)

k

logk

log Pow

Test Item

96.5

96.9

96.7

35.0

>0.37*

(1.54)**

>6.5*
(9.8)**

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

Conclusions:
The partition coefficient of the test item was estimated to be 9.8 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 > 3.1 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 9.8.

Description of key information

The partition coefficient of the test item was estimated to be 9.8 at 25 °C.

Key value for chemical safety assessment

Log Kow (Log Pow):
9.8
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 > 3.1 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 9.8 (reference 4.7-1).