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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:
from 2017-08-18 to 2017-09-06
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 830.7550 (Partition Coefficient, n-octanol / H2O, Shake Flask Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
flask method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
Pow
Partition coefficient:
0.008
Temp.:
20 °C
pH:
>= 2.28 - <= 2.69
Key result
Type:
log Pow
Partition coefficient:
-2.13
Temp.:
20 °C
pH:
>= 2.28 - <= 2.69
Details on results:
The calibration solutions were prepared in 0.5 – 100 μg/mL range. The calibration samples were analysed by HPLC-UV method with three replicate injections from each. The concentration of the test item was calculated with the help of the calibration equation.

Table 1. Measured concentrations

Ratio of solvents
(n-Octanol: Water)

Measured concentration in
n-octanol phase
(µg/mL)

Measured concentration in
aqueous phase
(µg/mL)

pH

4:1

4.72

621

2.50

4.71

618

2.49

4.56

622

2.49

Mean

4.66

620

2.49

RSD%

2

0

-

Meas. test item (Mo; Mw)

168 µg

5581 µg

-

Total nominal quantity of test item (Ms)

5773 µg

Total quantity of test item (Mo+ Mw) in the two-phase system:

5749 µg

Recovery:

100 %

Ratio of solvents
(n-Octanol: Water)

Measured concentration in
n-octanol phase
(µg/mL)

Measured concentration in
aqueous phase
(µg/mL)

pH

2:1

2.28

395

2.69

2.29

386

2.68

2.35

395

2.68

Mean

2.31

392

2.69

RSD%

2

1

-

Meas. test item (Mo; Mw)

69.3 µg

5874 µg

-

Total nominal quantity of test item (Ms)

5773 µg

Total quantity of test item (Mo+ Mw) in the two-phase system:

5943 µg

Recovery:

103%

8:1

10.3

1063

2.28

10.4

1102

2.28

9.77

1091

2.28

Mean

10.2

1085

2.28

RSD%

3

2

-

Meas. test item (Mo; Mw)

406 µg

5427 µg

-

Total nominal quantity of test item (Ms)

5773 µg

Total quantity of test item (Mo+ Mw) in the two-phase system:

5833 µg

Recovery:

101%

Table 2. Calculated partition coefficient (Pow) and log Pow

Ratio of solvents
(n-Octanol: Water)

Partition coefficient

Log Partition coefficient

Pow

Log Pow

4:1

0.0075

-2.12

2:1

0.0059

-2.23

8:1

0.0094

-2.03

Mean all

0.0076

-2.13

Conclusions:
The partition coefficient (log Pow) of the test item was determined to be -2.13 using the shake flask method. The result is also applicable for the anhydrous form of the test item.
Executive summary:

A study was conducted in accordance with OECD TG 107, Regulation (EC) No 440/2008 method A.8 and OPPTS 830.7550 to determine the partition coefficient of the test substance using the shake flask method. A stock solution of the test substance was prepared in n-octanol presaturated with water. The samples in the octanol phase were extracted with water. The water phase was diluted and analysed using HPLC. Test vessels with octanol/water mixture in different ratios were shaked for 5 minutes by hand. Separation of the two phases was achieved by centrifugation at 20 °C (5 min, 4000 rpm). Then the two phases were analysed using HPLC. The partition coefficient (log Pow) of the test item in its hydrated form was determined to be -2.13 at 20 °C. The partition coefficient for the anhydrous form is considered to be the same, as it is relevant for the organic part of the substance.

Description of key information

The partition coefficient (log Pow) of the test item was determined to be -2.13 using the shake flask method. The result is also applicable for the anhydrous form of the test item.

Key value for chemical safety assessment

Log Kow (Log Pow):
-2.13
at the temperature of:
20 °C

Additional information

A study (reference 4.7-1) was conducted in accordance with OECD TG 107, Regulation (EC) No 440/2008 method A.8 and OPPTS 830.7550 to determine the partition coefficient of the test substance using the shake flask method. A stock solution of the test substance was prepared in n-octanol presaturated with water. The samples in the octanol phase were extracted with water. The water phase was diluted and analysed using HPLC. Test vessels with octanol/water mixture in different ratios were shaked for 5 minutes by hand. Separation of the two phases was achieved by centrifugation at 20 °C (5 min, 4000 rpm). Then the two phases were analysed using HPLC. The partition coefficient (log Pow) of the test item in its hydrated form was determined to be -2.13 at 20 °C. The partition coefficient for the anhydrous form is considered to be the same, as it is relevant for the organic part of the substance.