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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:
2015
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)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
Principles of method if other than guideline:
None
GLP compliance:
no
Type of method:
flask method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: MH-20/2014
Analytical method:
other: UV-VIS
Key result
Type:
log Pow
Partition coefficient:
-4.74
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

1

5

5

60 min

undissolved

1

10

10

60 min

undissolved

1

50

50

60 min

undissolved

 

According to this preliminary test the solubility of the test item in n-octanol is above 20 mg/l (without correction of the purity).

Calculation of the partition coefficient log Pow from the preliminary tests

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

 

P ow = cs octanol /cs water

 

s= saturation

 

With the data obtained from the experiments in chapter 3.5.1 (cs > 20 mg/l) and with water solubility: cs = 257 g/l, the partition coefficient was calculated as log Pow -4.0.Due to the fact, that the estimated log Pow is below -2.0, 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

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

Aliquot of the flasks (ml)

1

1

1

1

End volume (ml)

5

5

5

5

Measured concentration (μg/ml)

18.5

17.7

17.3

--

Solubility (mg/l)

3.7

3.6

3.5

--

 

Table: Concentrations of the standards for recheck:

n-octanol solubility

(average): 80 mg/l Standard

Measured concentration

(μg/ml)

% Recovery

Sample C +

Standard 2 (c= 16.5 μg/ml)

33.9

100.6

Sample C +

Standard 3 (c= 33.0 μg/ml)

50.1

99.4

 

Recovery range from 99.4 % to 100.6 % 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: 3.6 mg/l.

By means of the flask method, the saturation concentration of the test item in water was determined to: 197 g/l

Table: Calculation of the partition coefficient from the individual solubility:

Pow = cs octanol /cs water

P ow

log P ow

3.6 mg/l / 197000 mg/l

1.83*10-5

-4.74


Conclusions:
The partition co-efficient n-octanol/water of FAT 40061/F at 20 °C was determined to be -4.74 (log Pow) (Pow = 0.0000183).
Executive summary:

The partition coefficient n-octanol / water of the test item was assessed in a study conducted according to EU Method A.8 and OECD Guideline 107 as well as OECD Guideline 117. Due to the fact, that the estimated log Pow based on the preliminary determination of n-octanol and water solubility (197 mg/l) is below -2,0, the partition coefficient n-octanol/water has to be estimated from the individual solubility in water and n-octanol. Hence, the solubility of the test item in n-octanol was determined using the flask method.

For the main test three flasks were prepared with about 100 mg and 5 ml n-octanol . The batches were stirred for different times at 30 °C (experiment A for 24 h, experiment B for 48 h, experiment C for 72 h) in tightly closed flasks. After equilibration (further stirring for 24 h at 20 °C), a saturated solution with a precipitate of the test item could be observed. Aliquots were taken and centrifuged (30 minutes with 5000 rpm at 20 °C). Subsequently , the solution was filtered over 0.20 μm microfilters. Another experiment was performed according to the procedure of experiment without the test item (“blank”). The concentration were quantified with absorbance vs concentration.

By means of the flask method, the saturation concentration of the test item in n-octanol was determined to be 3.6 mg/l. This was used with water solubility (197 mg/l) of test item, to arrive at the partition coefficient using the formula = saturation concentration of test item in n-octanol/saturation concentration of test item in water.

Based on the findings of the study, the partition co-efficient n-octanol/water of FAT 40061/F at 20 °C was determined to be -4.74 (log Pow) (Pow = 0.0000183).

Description of key information

The partition co-efficient n-octanol/water of FAT 40061/F at 20 °C was determined to be -4.74 (log Pow) (Pow = 0.0000183).

Key value for chemical safety assessment

Log Kow (Log Pow):
-4.74
at the temperature of:
20 °C

Additional information

The partition coefficient n-octanol / water of the test item was assessed in a study conducted according to EU Method A.8 and OECD Guideline 107 as well as OECD Guideline 117. Due to the fact, that the estimated log Pow based on the preliminary determination of n-octanol and water solubility (197 mg/l) is below -2,0, the partition coefficient n-octanol/water has to be estimated from the individual solubility in water and n-octanol. Hence, the solubility of the test item in n-octanol was determined to be 3.6 mg/l using the flask method. Based on the findings of the study, the partition co-efficient n-octanol/water of FAT 40061/F at 20°C was determined to be -4.74 (log Pow) (Pow = 0.0000183).