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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:
10-02-2015 to 03-03-2015
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:
-0.1
Temp.:
25 °C
pH:
3.3
Remarks on result:
other: trans-isomer
Key result
Type:
log Pow
Partition coefficient:
1.1
Temp.:
25 °C
pH:
3.3
Remarks on result:
other: cis-isomer

Calculation of the partition coefficient log Pow

The program KOWWIN (part of EPI Suite) was used for calculating the log Pow of the test item. The calculated value was 1.2. Therefore, according to the guidelines the partition coefficient n-octanol/water of the test item at room temperature was determined by the HPLC-method.

HPLC method

The test item consists of the two following isomers: cis-isomer (95 %) and trans-isomer (5 %). Therefore, the test item showed two HPLC signals with different retention times.

In the water solubility test the percentages of the two isomers in the present batch of the test item were determined by analysing the area% of the two isomers in the HPLC chromatograms of 5 different standard solutions (twofold injection) and by the calculation of the mean values. According to this area% HPLC analysis the cis- and trans- isomer of the present batch of the test item wereassigned to: cis-isomer (92.7 %) Peak 2 and trans-isomer (7.3 %) Peak 1.

Table 1: Determination of the dead time t0

Dead time
marker

tR / min
1. measurement

tR / min
2. measurement

tR / min
mean

Formamide

2.45

2.44

2.45

Dead time:   t0 = 2.45 min

Table 2: Calibration data 1st injection

Calibration substance

tR / min

k

log k

log Pow*

2-Butanone

2.90

0.19

-0.73

0.3

Acetanilide

3.07

0.26

-0.59

1.0

Cinnamyl alcohol

3.68

0.50

-0.30

1.9

2,6-Dichlorobenzonitrile

4.66

0.91

-0.04

2.6

Allyl phenyl ether

6.66

1.72

0.24

2.9

Benzophenone

6.02

1.46

0.17

3.2

Cumene

12.19

3.99

0.60

3.7

Diphenyl ether

11.19

3.58

0.55

4.2

Fluoranthene

22.46

8.19

0.91

5.1

4,4'-DDT

56.09

21.94

1.34

6.5

* OECD guideline 117, adopted 2004

Regression:      log Pow = a + b.log k

Parameters: a = 2.538
b = 2.800
r2 = 0.9814

Table 3: log Pow of the test item1st injection

Test item

tR / min

k

log k

log Pow

Peak 1 at 2.7 min
(trans-isomer, 5 %)

2.73

0.11

-0.94

<0.3*

(-0.1)**

Peak 2 at 3.2 min
(cis-isomer, 95 %)

3.20

0.31

-0.51

1.1

* below the lowest log Pow value of calibration substance (2-butanone)

** via extrapolation

Table 3: log Pow of the test item1st injection

Test item

tR / min

k

log k

log Pow

Peak 1 at 2.7 min
(trans-isomer, 5 %)

2.73

0.11

-0.94

<0.3*

(-0.1)**

Peak 2 at 3.2 min
(cis-isomer, 95 %)

3.20

0.31

-0.51

1.1

* below the lowest log Pow value of calibration substance (2-butanone)

** via extrapolation

Table 4: Calibration data 2nd injection

Calibration substance

tR / min

k

log k

log Pow*

2-Butanone

2.90

0.19

-0.73

0.3

Acetanilide

3.08

0.26

-0.59

1.0

Cinnamyl alcohol

3.68

0.51

-0.30

1.9

2,6-Dichlorobenzonitrile

4.67

0.91

-0.04

2.6

Allyl phenyl ether

6.69

1.74

0.24

2.9

Benzophenone

6.05

1.47

0.17

3.2

Cumene

12.28

4.02

0.60

3.7

Diphenyl ether

11.29

3.62

0.56

4.2

Fluoranthene

22.76

8.31

0.92

5.1

4,4'-DDT

55.85

21.85

1.34

6.5

* OECD guideline 117, adopted 2004

Regression:      log Pow = a + b.log k

Parameters: a = 2.531
b = 2.799
r2 = 0.9812

Table 5: log Pow of the test item2nd injection

Test item

tR / min

k

log k

log Pow

Peak 1 at 2.7 min
(trens-isomer, 5 %)

2.73

0.11

-0.94

<0.3*

(-0.1)**

Peak 2 at 3.2 min
(cis-isomer, 95 %)

3.21

0.31

-0.51

1.1

* below the lowest log Pow value of calibration substance (2-butanone)

** via extrapolation

Conclusions:
The test item consists of cis- and trans-isomer. The log Pow of the cis-isomer was determined to be 1.1 at 25 °C. The log Pow of the trans-isomer was determined to be <0.3 at 25 °C and extrapolated to be -0.1, as it was below the calibration curve.
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. After equilibration of the HPLC system, the calibration mixture was injected first, followed by the test chemical solution, the calibration mixture again and a second injection of the test item. The test item consists of the two following isomers: cis-isomer (95 %) and trans-isomer (5 %). Therefore, the test item showed two HPLC signals with different retention times. The log Pow of the cis-isomer was determined to be 1.1 at 25 °C. The log Pow of the trans-isomer was determined to be <0.3 at 25 °C and extrapolated to be -0.1, as it was below the calibration curve.

Description of key information

The test item consists of cis- and trans-isomer. The log Pow of the cis-isomer was determined to be 1.1 at 25 °C. The log Pow of the trans-isomer was extrapolated -0.1 at 25 °C.

Key value for chemical safety assessment

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. After equilibration of the HPLC system, the calibration mixture was injected first, followed by the test chemical solution, the calibration mixture again and a second injection of the test item. The test item consists of the two following isomers: cis-isomer (95 %) and trans-isomer (5 %). Therefore, the test item showed two HPLC signals with different retention times. The log Pow of the cis-isomer was determined to be 1.1 at 25 °C. The log Pow of the trans-isomer was determined to be <0.3 at 25 °C and extrapolated to be -0.1, as it was below the calibration curve (reference 4.7-1).