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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:
April 06, 2018 - April 19, 2018
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
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:
1
Temp.:
25 °C
pH:
5

Preliminary visual estimation of the n-octanol solubility

Different amounts of the test item were stirred with increasing volumes of n-octanol at room temperature and visually checked for any undissolved parts.

Table2: Results of the preliminary visual estimation of the n-octanol solubility

Added amount of test item

/ mg

Total amount of test item / mg

Total volume of n-octanol

/ ml

Stirring time

/ min

Appearance of mixture

13.4

13.4

10

10

dissolved

116.8

116.8

2.5

20

dissolved

48.0

164.8

2.5

30

dissolved

54.4

219.2

2.5

35

dissolved

153.9

373.1

2.5

60

dissolved

198.7

571.8

2.5

3 d

Not dissolved

According to this preliminary test the solubility of the test item in n-octanol was within the range 149 – 229 g/L (without correction for the purity).

Calculation of the partition coefficient log POW from the preliminary test

The partition coefficient POWmay be estimated from the saturation concentrations in n-octanol and water. The estimated partition coefficient was calculated with the water solubility data determined in project 20170187.05 (cS = 21 g/L) and the data obtained above. It was calculated to be: log POW < 1. 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 results from the HPLC method are summarized inTable3to Table 7.

Table3: Determination of the dead time t0

Dead time marker

tR / min

1st injection

tR / min

2st injection

tR / min
mean

Formamide

1.22

1.22

1.22

 


 

Table4: Calibration data 1st injection

Calibration substance

tR / min

k

log k

log POW 1)

2-Butanone

1.41

0.15

-0.83

0.3

Cinnamyl alcohol

1.73

0.41

-0.38

1.9

2,6-Dichlorobenzonitrile

2.14

0.75

-0.12

2.6

Allyl phenyl ether

3.00

1.46

0.16

2.9

Benzophenone

2.72

1.22

0.09

3.2

Cumene

5.43

3.44

0.54

4.2

Diphenyl ether

4.99

3.08

0.49

4.2

1)OECD guideline 117, adopted 2004

Regression:        

                           Parameters:        a = 2.7085

                                                        b = 2.592

                                                        r2= 0.9513

Table5: log POWof the test item – 1stinjection

Test item

tR/ min

k

log k

log POW

Basic Yellow 21 Chloride

1.49

0.22

-0.66

1.0

 

Table6: Calibration data 2ndinjection

Calibration substance

tR / min

k

log k

log POW 4)

2-Butanone

1.41

0.15

-0.82

0.3

Cinnamyl alcohol

1.73

0.41

-0.38

1.9

2,6-Dichlorobenzonitrile

2.14

0.75

-0.12

2.6

Allyl phenyl ether

3.01

1.46

0.16

2.9

Benzophenone

2.72

1.22

0.09

3.2

Cumene

5.43

3.44

0.54

4.2

Diphenyl ether

5.00

3.08

0.49

4.2

4)OECD guideline 117, adopted 2004

Regression:        

                           Parameters:        a = 2.7051

                                                        b = 2.596

                                                        r2= 0.9512


 

Table7: log POWof the test item – 2nd injection

Test item

tR/ min

k

log k

log POW

Basic Yellow 21 Chloride

1.49

0.22

-0.66

1.0

The partition coefficient POW of the test item at pH 5 was determined to be:

log POW= 1.0

Executive summary:

The partition coefficient n-octanol/water of the test item at pH 5 was determined according to the HPLC method.

It was found to be:

log POW = 1.0

Description of key information

The partition coefficient n-octanol/water of the test item at pH 5 was determined according to the HPLC method.

It was found to be:

log POW = 1.0

Key value for chemical safety assessment

Log Kow (Log Pow):
1
at the temperature of:
25 °C

Additional information