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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.-27.01.2012
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.:
25 °C
Remarks on result:
other: pH not known
Key result
Type:
log Pow
Partition coefficient:
7.7
Temp.:
25 °C
Remarks on result:
other: via extrapolation

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

16.4

100

undissolved

7.4

500

undissolved

1.2

500

undissolved

 The solubility of the test item in water was below 2.4 mg/L (without correction of the purity).

 

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

0.1031

0.1031

10

30

undissolved

-

0.1031

50

30

undissolved

-

0.1031

100

1000

undissolved

0.0071

0.0071

10

40

undissolved

-

0.0071

20

86

dissolved

 

 The solubility of the test item in n-octanol is is between 0.36 g/L and 0.71 g/L (without correction of the pruity).

 With the data obtained the partition coefficient was calculated as: log Pow > 1.6. 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

0.98

0.98

0.98

 

 

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

1.09

1.09

1.09

0.11

-0.96

0.3

Acetanilide

1.09

1.09

1.09

0.12

-0.93

1.0

Cinnamyl alcohol

1.16

1.16

1.16

0.18

-0.74

1.9

2,6-Dicholoro-
benzonitrile

1.28

1.28

1.28

0.31

-0.51

2.6

Allyl phenyl ether

1.50

1.50

1.50

0.53

-0.27

2.9

Benzophenone

1.43

1.43

1.43

0.46

-0.34

3.2

Cumene

1.97

1.97

1.97

1.01

0.00

3.7

Diphenyl ether

1.82

1.82

1.82

0.86

-0.07

4.2

Fluoranthene

2.70

2.70

2.70

1.76

0.25

5.1

4,4' DDT

3.23

3.23

3.23

2.30

0.36

6.5

Regression: logPow = a + b logk

Parameters: a = 4.39, b = 3.8, r2 = 0.9479

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

8.05

8.05

8.05

7.23

0.86

> 6.5

(7.7)*

 * via extrapolation

 

Conclusions:
The logPow of the test item was greater than 6.5 at 25 °C (above the highest log Pow value of calibration substance DDT). The logPow value was determined to be 7.7 via extrapolation.
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. Therefore, 577 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 90:10 % (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 90:10 % (v/v)  and injected as single solutions twice. 14.0 mg of the test item were dissolved in 25 mL methanol and diluted from 0.1 mL to 1.0 mL with methanol / distilled water 90:10 % (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 greater than 6.5 at 25 °C (above the highest log Pow value of calibration substance DDT). The logPow value was determined to be 7.7 via extrapolation.

Description of key information

The logPow of the test item was greater than 6.5 at 25 °C (above the highest log Pow value of calibration substance DDT). The logPow value was determined to be 7.7 via extrapolation.

Key value for chemical safety assessment

Log Kow (Log Pow):
7.7
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. Therefore,577 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 90:10 % (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 90:10 % (v/v)  and injected as single solutions twice. 14.0 mg of the test item were dissolved in 25 mL methanol and diluted from 0.1 mL to 1.0 mL with methanol / distilled water 90:10 % (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 greater than 6.5 at 25 °C (above the highest log Pow value of calibration substance DDT). The logPow value was determined to be 7.7 via extrapolation.