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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:
From June 29, 2006 to July 07, 2006
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
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
< -7.3
Temp.:
20 °C
Remarks on result:
other: pH not determined
Details on results:
Octanol solubility of the test substance (average of three experiment and without correction of purity): <8.23 µg/L
The saturation concentration of the test substance in water was determined by means of the flask method in project '20060234.02' to 145.8 g/L (without correction for the purity).
From the individual solubilities the log Pow was calculated to be <-7.3.

Preliminary Visual Estimation of the n-Octanol Solubility

An amount of the test substance was stirred with increasing amounts of n-octanol at room temperature.

 

Table: Appearance of the test mixtures 

Amount of the test substance in mg

Total volume in mL

Stirring time (h)

Appearance of mixture

Solubility (mg/L)

11.07

100

0.83

undissolved

 

 

200

1.17

undissolved

 

 

300

0.58

undissolved

 

 

500

0.5

undissolved

 

 

750

0.5

undissolved

 

 

1000

17.42

undissolved

< 11.07

 

The solubility of the test item in n-octanol was below 11.07 mg/L(without correction for the purity).

 

Calculation of the Partition Coefficient log Pow from the preliminary tests

The partition coefficient was calculated as log Pow lower than -4.12. Due to this fact the partition coefficient n-octanol/water of the test substance at ambient temperature had to be estimated by the flask method (individual solubilities).

 

Calculation of the Partition Coefficient log Pow from the individual solubilities

Table: Octanol solubility of the test substance - experiments A to D  

Experiment

 

A

B

C

D (blank)

Amount of test substance (mg)

3.27

2.98

3.69

-

Stirring time at 20°C (h)

24

24

24

24

Aliquot (mL)

10

10

10

10

End volume (mL)

 

2

2

2

2

Measured concentration (µg/L)

 

<41.131

<41.13

<41.131

<41.13

<41.131

<41.13

-

Mean concentration (µg/L)

 

<41.13

<41.13

<41.13

-

Octanol solubility (µg/L)

 

<8.23

<8.23

<8.23

-

  

Average experiments A to C (without correction for the purity): <8.23µg/L

The saturation concentration of the test substance in water was determined by means of the flask method in project '20060234.02' to 145.8 g/L (without correction for the purity).

From the individual solubilities the log Pow was calculated to be <-7.3.

 

Concentrations of standards for recheck

 

Standard

Measured concentration (Mg/L)

%Recovery

Standard J (c=41.13 µg/L)

39.86/139.52

96.5

Standard K (c=122 µg/L)

117.0/115.4

94.6

 

Recoveries of the standards ranged from 94.6% to 96.5%, indicating a good accuracy of the analytical method.

Conclusions:
Under the study conditions, the partition coefficient n-octanol/water of the test substance at room temperature, performed according to the flask method (individual solubilities in water and n-octanol), was determined to be <-7.3.
Executive summary:

The partition coefficient of the test substance was determined according to the flask-shaking method. Samples were prepared in aqueous and n-octanol phases. After sample preparation, the concentration of the test substance was determined by HPLC.

The saturation concentration of the test substance in water was determined to be 145.8 g/L and the octanol solubility (µg/L) was found to be <8.23. Under the study conditions, the partition coefficient n-octanol/water of the test substance at room temperature, performed according to the

flask method (individual solubilities in water and n-octanol), was determined to be <-7.3.

Description of key information

The partition coefficient n-octanol/water of the test substance at room temperature was determined to be <-7.3 (Moller, 2006).

Key value for chemical safety assessment

Log Kow (Log Pow):
-7.3
at the temperature of:
20 °C

Additional information