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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:
2014
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
GLP compliance:
no
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
-5.33
Temp.:
20 °C
Remarks on result:
other: pH not specified

Individual Results:

Preliminary Visual Estimation of the n-octanol solubility

Different amounts 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

100

10

10

60 min

undissolved

100

50

50

60 min

undissolved

10

10

10

60 min

undissolved

10

50

50

95 min

undissolved

 10  100  100  95 min  undissolved

According to this preliminary test the solubility of the test item in n-octanol is below 100 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 < 100 mg/L) and in the preliminary test (water solubility: cs = 376 g/L) the partition coefficient was calculated as log Pow below -3.6.

Due to the fact that the log Pow is below -2, the partition coefficient n-octanol/water has to be estimated from the individual solubility in water and n-octanol.

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

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

Experiment

A

B

C

D (blank)

Amount of test item (mg)

100

100

100

--

Stirring time at 30 °C (h)

24

48

72

72

End volume (mL)

5

5

5

5

Measured concentration (μg/mL)

1.73

2.01

1.66

--

Solubility (mg/L)

1.73

2.01

1.66

--

The values of the measured concentrations of the test item in n-octanol is 1.75 mg/L.

Table: Concentrations of the standards for recheck:

Standard

Measured concentration

(μg/mL)

% Recovery

Standard 1 (c: 1.37 μg/ml)

1.38

100.7

 Standard 2 (c: 6.85 μg/ml)

 6.92

 101.0

 Standard 4 (c: 27.4 μg/ml)

 27.2

 99.3

Recovery ranged from 99.3 to 101 % indicating a sufficient accuracy of the analytical method.

Calculation of the partition coefficient log Pow from the individual solubility

By means of the flask method, the saturation concentration of the test item in n-octanol was determined to: 1.75 mg/l

By means of the flask method, the saturation concentration of the test item in water was determined to: 376.0 g/l

Based on the above values, Pow was calculated as 1.75/376000 equaling 4.65E-6 and log Pow equal to -5.33.

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 -5.33 (log Pow).
Executive summary:

The n-octanol/water partition coefficient of FAT 40045/Z TE was determined in a study conducted according to OECD Guideline 107 and 117. The flask method was used for the purpose. Based on the individual solubility of the test item in n-octanol and water, the partition coefficient n-octanol/water of the test item at 20 °C, was determined to be -5.33 (log Pow).

Description of key information

The n-octanol/water partition coefficient of FAT 40045/Z TE was determined in a study conducted according to OECD Guideline 107 and 117. The flask method was used for the purpose. Based on the individual solubility of the test item in n-octanol and water, the partition coefficient n-octanol/water of the test item at 20 °C was determined to be -5.33 (log Pow).


Key value for chemical safety assessment

Log Kow (Log Pow):
-5.33
at the temperature of:
20 °C

Additional information