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Physical & Chemical properties

Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From August 31st, 2018 to September 7th, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
2.44
Temp.:
20 °C
pH:
>= 7.15 - <= 9.65

Table 1. Calculated values 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

251.87

280.15

348.91

408.35

200.10

225.46

log Pow = Log(C1-octanol/Cwater)

2.40

2.45

2.54

2.61

2.30

2.35

Average log Pow + standard deviation

2.42 ± 0.03

2.58 ± 0.05

2.33 ± 0.04

Average log Pow + standard deviation

2.44 ± 0.13

Table 2. Calibration solution

Weight [mg]

Dilution [ml]

Cw [mg/ml]

 Peak area

Average peak area Aw

f

Average f

13.02

25-1.0-10-0.5-10

0.00259098

279729

278180

278954.5

0.00000929

0.00000939

25-1.0-10-1.0-10

0.00518196

544758

546088

545423

0.00000950

Table 3: Study solution

 

Sample

Weight of the

sample [mg]

 

Dilution [ml]

 

Cp [mg/ml]

 

Peak area

Average peak area

Ap

 

X

[g/kg]

1/w

1003.55

1

1003.55

353724

371135

362429.5

0.0034

2/w

999.86

1

999.86

346762

358338

352550.0

0.0033

3/w

1007.77

1

1007.77

422212

423035

422623.5

0.0039

4/w

1001.30

1

1001.3

345588

349940

347764.0

0.0033

5/w

839.75

1

839.75

308303

325966

317134.5

0.0035

6/w

922.03

1

922.03

296410

306861

301635.5

0.0031

stock

817.64

10-1.0-10

8.1764

5065095

5113041

5089068

5.8472

1/o

812.07

10

81.207

8907191

9037464

8972327.5

1.0380

2/o

820.70

10

82.070

9742444

9836203

9789323.5

1.1206

3/o

811.61

10

81.161

14241398

14257812

14249605

1.6494

4/o

813.54

10

81.354

13765229

14524818

14145024

1.6334

5/o

817.17

10

81.717

7382212

7385229

7383720.5

0.8489

6/o

819.09

10

81.909

7346936

7426651

7386793.5

0.8472

 

Table 4. Results of measurements at 20.0 ± 1.0 ºC

Vial number

1

2

3

4

5

6

Temperature, °C

20.1

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 1-octanol phase/volume of water phase

1:1

1:2

2:1

Tested substance concentration in water phase, g/L

0.0034

0.0033

0.0039

0.0033

0.0035

0.0031

Tested substance concentration in 1- octanol phase, g/kg

1.038

1.1206

1.6494

1.6334

0.8489

0.8472

Tested substance concentration in 1- octanol phase, g/L

0.8564

0.9245

1.3608

1.3476

0.7003

0.6989

Mass of tested substance in water phase

x 10^3, g

0.0170

0.0165

0.0261

0.0221

0.0116

0.0102

Mass of 3 tested substance in 1-octanol phase x 10^3, g

4.2818

4.6225

4.4905

4.4469

4.6923

4.6829

Mass of tested substance in both phases

x 10^3, g

4.2988

4.6390

4.5166

4.4690

4.7039

4.6931

Added mass of tested substance x 10^3, g

4.8239

4.8239

4.8239

4.8239

4.8239

4.8239


 Table 5. Measured pH values of water phase

Vial number

1

2

3

4

5

6

pH before test

6.9

6.9

6.9

6.9

6.9

6.9

pH after test

9.65

9.62

8.71

7.62

7.15

7.15

Conclusions:
The partition coefficient of the test item (logPow) was 2.44 at 20ºC.
Executive summary:

The 1-octanol/water partition coefficient of the test item was determined using the shake flask method and following OECD Guideline 107 and EU method A.8, under GLP conditions. Water and 1-octanol phases were saturated by shaking, at a temperature of 20 ± 1ºC. Three tests were performed using three different ratios of 1-octanol to water (1:1, 1:2, 2:1) and the concentration of the test item in each solution was measured by means of a validated HPLC method. Two replicate measurements per ratio were performed. The average partition coefficient (log Pow) of the test item was 2.44 at 20 ± 0.5ºC

Description of key information

Key study. Method according to OECD 107/ EU A.8, GLP study. The average 1-octanol/water partition coefficient of the test item (log Kow) is 2.44 at 20ºC.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.44
at the temperature of:
20 °C

Additional information