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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:
2013
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
GLP compliance:
no
Type of method:
flask method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
FAT 36014/Z
Analytical method:
other: UV/VIS
Key result
Type:
log Pow
Partition coefficient:
2.73
Temp.:
20 °C
Remarks on result:
other: pH not specified

Individual Results:

Preliminary Visual Estimation of the n-octanol solubility

100 mg of the test item were stirred with different amounts of n-octanol at room temperature and visually checked for any undissolved particles.

Table: Appearance of the test mixtures

Amount of test item in mg

Volume in ml

Total volume in ml

Stirring time

Appearance of mixture

10

1

1

60 min

undissolved

10

5

5

60 min

dissolved

10

10

10

60 min

dissolved

10

50

50

60 min

dissolved

According to this preliminary test the solubility of the test item in n-octanol is above 200 mg/L (without correction of the purity).

Calculation of the partition coefficient log Pow from the preliminary tests

The partition coefficient Pow may be estimated from the saturation concentrations in n-octanol and water by the following equation:

Pow = cs octanol /cs water

s = saturation

With the data obtained from the preliminary experiments above (octanol solubility cs >2000 mg/L) and in the preliminary test (water solubility: cs = 5.14 mg/L) the partition coefficient was calculated as log POW >2.6.

Due to the fact, that the water solubility is nearly the LoQ, the partition coefficient n-octanol/water has to be estimated from the individual solubilities in water and n-octanol.

Determination of the solubility in the n-Octanol phase: Flask Methods

Table: Solubility of the test item –experiments A to D

Experiment

A

B

C

D (blank)

Amount of test item (mg)

500

500

500

--

Stirring time at 30 °C (h)

24

48

72

72

Aliquot of the flasks (mL)

0.05

0.05

0.05

0.05

End volume (mL)

10

10

10

10

Measured concentration (μg/mL)

12.79

12.65

13.92

--

Solubility (mg/L)

2557

2530

2785

--

Table: Concentrations of the standards for recheck:

Standard

Measured concentration

(μg/mL)

% Recovery

Standard 2 (c = 5.35 μg/mL)

5.38

100.6

Standard 3 (c = 10.7 μg/mL)

10.85

101.4

Standard 4 (c = 21.4 μg/mL)

21.2

99.1

Recovery range from 99.1 % to 101.4 % indicates a sufficient accuracy of the analytical method.

Calculation of the partition coefficient log Pow from the individual solubilities

By means of the flask method, the saturation concentration of the test item in n-octanol was determined to: 2785 mg/L.

By means of the flask method, the saturation concentration of the test item in water was determined to: 5.14 mg/L.

Conclusions:
The partition coefficient n-octanol/water of the test item at 20 °C, from the individual solubility in water and n-octanol, was determined to be 2.73 (log Pow).
Executive summary:

The partition coefficient n-octanol/water of FAT 36014/Z at 20 °C was determined using shake flask method as described in OECD Guideline 107. According to the shake flask method, the solubility of FAT 36014/Z in n-octanol is 2785 mg/L. The water solubility of FAT 21030/E was determined to be 5.14 mg/L. Hence, the partition coefficient (log Pow) was calculated to be 2.73.

Description of key information

The partition coefficient n-octanol/water of FAT 36014/Z at 20 °C was determined using shake flask method as described in OECD Guideline 107. According to the shake flask method, the solubility of FAT 36014/Z in n-octanol is 2785 mg/L. The water solubility of FAT 21030/E was determined to be 5.72 mg/L. Hence, the partition coefficient (log Pow) was calculated to be 2.69.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.69
at the temperature of:
20 °C

Additional information