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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:
03 February 2014 06 February 2014.
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:
yes
Remarks:
method not applicable.
Principles of method if other than guideline:
According to the OECD guideline 107 before deciding on what procedure to use, a preliminary estimate of the Pow should be obtained from calculation; according to the Pow calculation method described in the annex of the OECD guideline 117 the preliminary estimated log Pow resulted below -2.26. Therefore, the partition coefficient n-octanol / water was estimated from the individual solubility of the test item in water and n-octanol.
GLP compliance:
no
Type of method:
other: Calculation from the individual solubility.
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
FAT 66042/Z TE
Lot: 0003340600
Analytical method:
other: TLC
Type:
log Pow
Partition coefficient:
-3.39
Temp.:
20 °C
Remarks on result:
other: Determined from the individual solubility in water and n-octanol.

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.

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 50 min undissolved
10 50 50 95 min undissolved
1 10 10 95 min undissolved
0.1 10 10 95 min undissolved

According to this preliminary test the solubility of the test item in n-octanol is below 10 mg/l (without correction of the purity).

Calculation of the partition coefficient log Pow from the preliminary tests

With the data obtained from the experiments above (cs < 10 mg/l) and in the preliminary test (water solubility: cs = 1.83 g/l) the partition coefficient was calculated as log Pow below -2.26. 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 Methods

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) 0.68 0.74 0.87 /
Solubility (mg/l) 0.68 0.74 0.87 /

The values of the measured concentrations of the test item in n-octanol are 0.74 mg/l.

Concentrations of standards for recheck

Standard Measured concentration
(μg/ml)
Recovery rate
Standard 1 (c = 0.92 μg/ml) 0.91 98.90 %
Standard 2 (c = 2.30 μg/ml) 2.32 100.90 %
Standard 4 (c = 9.20 μg/ml) 9.22 100.20 %

Recovery range from 98.9 % to 100.9 % indicates 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: 0.74 mg/l

By means of the flask method, the saturation concentration of the test item in water was determined to: 1.83 g/l

Calculation of the partition coefficient from the individual solubility

Pow = cs octanol / CS water Pow logPow 
0.74 mg/l / 1830 mg/l 4.05 * 10-4 -3.39
Conclusions:
log Kow: - 3.392 at 20 °C
Executive summary:

According to the OECD guideline 107 before deciding on what procedure to use, a preliminary estimate of the Pow should be obtained from calculation; according to the Pow calculation method described in the annex of OECD guideline 117 the preliminary estimated log Pow resulted below -2.26. Therefore, the partition coefficient n-octanol / water was estimated from the individual solubility of the test item in water and n-octanol.

Based on the study results, the partition coefficient n-octanol/water of the test item at 20 °C, from the individual solubility in water and n-octanol, was log Kow: - 3.392

Description of key information

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: log Kow = - 3.392

Key value for chemical safety assessment

Log Kow (Log Pow):
-3.392
at the temperature of:
20 °C

Additional information

According to the OECD guideline 107 before deciding on what procedure to use, a preliminary estimate of the Pow should be obtained from calculation; according to the Pow calculation method described in the annex of OECD guideline 117 the preliminary estimated log Pow resulted below -2.26. Therefore the partition coefficient n-octanol / water was estimated from the individual solubility of the test item in water and n-octanol.

Based on the study results, the partition coefficient n-octanol/water of the test item at 20 °C, from the individual solubility in water and n-octanol, was log Kow: - 3.392