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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:
March 15, 2019
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)
Version / remarks:
2004
Deviations:
no
GLP compliance:
yes
Remarks:
Swiss Federal Office of Public Health, Consumer protection directorate, Notification authority for chemicals, Bern, Switzerland
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
>= 4.57 - <= 4.79
Temp.:
20 °C
pH:
7.39
Remarks on result:
other: based on four peaks representing >95% of the test item (area %)

Results of the calibration

The R² fit of the calibration curve used was 0.9956. The deviations of calculated log Pow-values from actual log Pow-values were 2.5 % at maximum. This reflects the linear correlation between the logarithms of the capacity factors of the HPLC system and the log Pow-values of the reference items in the applied range of 3.0 to 6.5.

Results of the partition coefficient determination for the test item

The test item showed a chromatographic profile consisting of several peaks. It could be verified that the four peaks with retention times between 8.3 and 9.7 minutes are representing more than 95 % of the test item (area %). The evaluation was based on these peaks.The log Pow-values for the compounds relating to these peaks were found to be 4.57 (Peak 1), 4.62 (Peak 2), 4.69 (Peak 3) and 4.79 (Peak 4). The data are given in the following table.

Peak Number

Solution

Run

Retention Time

[min]

 

Thiourea (dead time)

Solution 1

1strun

1.073

 

2ndrun

1.073

 

Solution 2

1strun

1.067

 

2ndrun

1.067

 

Peak Number

Solution

Run

Retention Time

[min]

log k'

Log Pow

Mean

Standard Deviation

Test Item
Peak 1

Solution 1

1strun

8.380

0.833

4.57

4.57

±0.01

2ndrun

8.380

0.833

4.57

Solution 2

1strun

8.373

0.836

4.58

2ndrun

8.373

0.836

4.58

Test Item
Peak 2

Solution 1

1strun

8.620

0.847

4.61

4.62

±0.00

2ndrun

8.627

0.848

4.61

Solution 2

1strun

8.613

0.850

4.62

2ndrun

8.613

0.850

4.62

Test Item
Peak 3

Solution 1

1strun

9.080

0.873

4.69

4.69

±0.00

2ndrun

9.087

0.873

4.69

Solution 2

1strun

9.073

0.875

4.70

2ndrun

9.073

0.875

4.70

Test Item
Peak 4

Solution 1

1strun

9.700

0.905

4.79

4.79

±0.00

2ndrun

9.707

0.906

4.79

Solution 2

1strun

9.693

0.908

4.80

2ndrun

9.693

0.908

4.80

Conclusions:
The partition coefficient (n-octanol/water) of the test item was determined using the HPLC method. The log Pow-values based on four peaks representing more than 95 % of the test item (area %) ranged from 4.57 to 4.79.

Description of key information

Log Pow range: 4.57 to 4.79 at 20°C (OECD 117, HPLC Method)

Key value for chemical safety assessment

Log Kow (Log Pow):
4.79
at the temperature of:
20 °C

Additional information

The partition coefficient (n-octanol/water) of the test item was determined using the HPLC method. Since the test item is a mixture of several constituents, the log Pow-values of the compounds assigned to each peak were evaluated. The peaks with retention times in a range of 16.7 to 20.8 minutes are representing more than 95 % of the test item (area %). The evaluation was based on these peaks and the log Pow-values ranged from 4.57 to 4.79.