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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 October 24th to October 26th, 2016.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
flask method
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Analytical method:
photometric method
Key result
Type:
log Pow
Partition coefficient:
0.67
Temp.:
20 °C
pH:
> 6.2 - < 6.7

Table 1. Results of measurements at 20.0 ºC.

Vial number

1

2

3

4

5

6

Temperature, ºC

20.0

20.0

19.9

 19.9

 20.1

 20.1

Volume of added stock solution, mL

1

1

1

1

1

1

Volume of water, mL

5

5

6.7

6.7

3.3

3.3

Volume of 1-octanol, mL

4

4

2.3

2.3

5.7

5.7

Volume of 1-octanol phase /volume
of water phase

1:1

1:1

 1:2

1:2

 2:1

 2:1

Neohesperidin Dihydrochalcone
concentration
in water phase, g/L

0.086

0.085

0.107

0.108

0.068

0.068

Neohesperidin Dihydrochalcone
concentration
in 1-octanol phase, g/kg

0.471

0.463

0.600

0.603

0.393

0.380

Neohesperidin Dihydrochalcone
concentration
in 1-octanol phase, g/L

0.389

0.382

0.495

0.497

0.324

0.314

Mass of Neohesperidin
Dihydrochalcone
in water phase (x1E3), g

0.430

0.425

0.717

0.724

0.224

0.224

Mass of Neohesperidin
Dihydrochalcone
in 1-octanol phase (x1E3), g

1.945

1.910

1.634

1.640

2.171

2.104

Mass of Neohesperidin
Dihydrochalcone
in both phases (x1E3), g

2.375

2.335

2.351

2.364

2.395

2.328

Added mass of
test item (x1E3), g

2.495

2.495

2.495

2.495

2.495

2.495


Table 2. Measured pH values of the water phase.

Vial number

1

2

3

4

5

6

pH before test

6.25

6.24

6.15

6.16

6.69

6.69

pH after test

6.25

6.25

6.16

6.15

6.70

6.69

Table 3. Determination of test item content in water phase and 1-octanol phase.

Sample

Weight
of the
sample
[mg]

Dilution
[mL]

Cp
[mg/mL]

Average peak
area
Ap

X
[g/kg]

1/w

1481.

5

296.32

0.933

0.086

2/w

1490.85

5

298.17

0.935

0.085

3/w

1501.45

5

300.29

1.181

0.107

4/w

1509.15

5

301.83

1.198

0.108

5/w

1506.35

5

301.27

0.762

0.068

6/w

1513.05

5

302.61

0.764

0.068

stock

329.95

10-1-5

6.60

0.738

3.024

1/o

329.55

10

32.96

0.578

0.471

2/o

317.25

10

31.73

0.548

0.463

3/o

336.9

10

33.69

0.747

0.600

4/o

325.2

10

32.52

0.726

0.603

5/o

315.8

10

31.58

0.466

0.393

6/o

336.6

10

33.66

0.479

0.380


Table 4. Calculated values logarithm to base 10 of partition coefficient 1-octanol/water.

Vial number

1

2

3

4

5

6

volume 1-octanol phase/volume
of water phase

1:1

1:2

2:1

Pow = C1-octanol/Cwater

4.52

4.49

4.63

4.60

4.76

4.62

log Pow = log(C1-octanol/Cwater)

0.66

0.65

0.67

0.66

0.68

0.66

Average log Pow + standard
deviation

0.66 ± 0.01

0.67 ± 0.01

0.67 ± 0.01

Average log Pow + standard
deviation

0.67 ± 0.01



Conclusions:
The value of log Kow of the test item at 20ºC is 0.67 ± 0.01 (pH 6.2 - 6.7).
Executive summary:

The determination of the test substance's partition coefficient 1-octanol/water was carried out according to OECD TG 107 and EU A.8, shake flask method, under GLP conditions. Water and 1 -octanol phases were mutually saturated and the amount of test item in each phase was determined by UV-VIS spectrophotometry. Taking into account the solubility of the test substance in water and its solubility in 1-octanol, the partition coefficient was calculated. The partition coefficient 1-octanol/water (log Pow) at 20.0 °C of the test item is 0.67 ± 0.01 (pH 6.2 - 6.7).

Description of key information

Key study. Method according to OECD 107 / EU Method A.8 (shake flask method), GLP study. The partition coefficient 1-octanol/water (log Pow) at 20.0 °C of the test item is 0.67 ± 0.01 (pH 6.2 - 6.7).

Key value for chemical safety assessment

Log Kow (Log Pow):
0.67
at the temperature of:
20 °C

Additional information

The determination of the test substance's partition coefficient 1-octanol/water was carried out according to OECD TG 107 and EU A.8, shake flask method, under GLP conditions. Water and 1 -octanol phases were mutually saturated and the amount of test item in each phase was determined by UV-VIS spectrophotometry. Taking into account the solubility of the test substance in water and its solubility in 1-octanol, the partition coefficient was calculated. The partition coefficient 1-octanol/water (log Pow) at 20.0 °C of the test item is 0.67 ± 0.01 (pH 6.2 - 6.7).