Registration Dossier

Physical & Chemical properties

Partition coefficient

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 24, 2018 to June 19, 2018
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)
Version / remarks:
Solubility in n-octanol by Flask method
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Version / remarks:
Solbility in n-octanol by Flask method
Deviations:
no
GLP compliance:
no
Type of method:
flask method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
-2.3
Temp.:
20 °C
Remarks on result:
other: estimated based on the ratio of their water solubility (according to OECD 105) and their octanol solubility (based on the principle of OECD 105).

Individual Results

Preliminary visual estimation of the n-octanol solubility

Defined amounts of the test item were stirred with increasing volumes of n-octanol at room temperature and visually checked for any undissolved particles.

Table3: Results of the preliminary visual estimation of the n-octanol solubility

Amount of test item

/ mg

Added volume of n-octanol

/ mL

Total volume of n-octanol

/ mL

Stirring time

/ h

Appearance of mixture

12.2

10

10

2

dark blue solution with black precipitate

40

50

1

dark blue solution with black particles

150

200

2

dark blue solution with black particles

According to this preliminary test the solubility of the test item in n-octanol was below 1.2 g/L (without correction for the purity). The dark blue colour of the three mixtures made it difficult to assess the n-octanol solubility visually. Therefore the more diluted mixtures with no apparent precipitate were not taken into account.

Calculation of the log POWfrom the preliminary test

The partition coefficient POWmay be estimated from the saturation concentrations in n-octanol and water.

The estimated partition coefficient was calculated with the water solubility data determined in project 20150018.04rev1 (cS = 92 g/L) and the data obtained in chapter above. It was calculated to be: log POW < -1.9.

The shake flask method was not applicable because the present test item was surface active. The HPLC method was not applicable due to the low estimated log POW. Therefore the partition coefficient was estimated based on the ratio of the solubilities in water and octanol. The octanol solubility was determined using the flask method.

Determination of the solubility in n-octanol: Flask method

The individual saturation solubility of the test item in n-octanol was performed within this study. After that, the partition coefficient was estimated based on the ratio of the test item solubility in n-octanol and water.

The flask method was performed as described above. Only the equilibration time at 20 °C was prolonged into 72 h instead of

After the equilibration time of the flask method aliquots of the mixtures were taken and centrifuged (30 minutes with 15000 rpm at 20 °C). Aliquots of the aqueous phases were sampled and filtered twice over a 0.2 µm HPLC syringe filter. Subsequently the aliquots were diluted from 0.25 mL to 10 mL and again from 0.5 mL to 1.0 mL with the mobile phase.The concentration of the test item was determined by HPLC.

All samples were injected as single solutions twice.

The data for the evaluation are given in Table4. The n-octanol solubility was calculated from the measured and unrounded concentration values and not from the rounded values given in Table4.

Table4: n-Octanol solubility experiments of the test item

Experiment

24 h experiment

48 h experiment

72 h experiment

blank

experiment (72 h)

Amount of test item / mg

601

603

605

--

Amount of octanol / mL

20

20

20

20

Stirring time at 30 °C / h

24

48

72

72

Dilution factor

80

80

80

80

Measured concentration / mg/L

5.47 / 5.47

7.18 / 8.77

6.02 / 6.17

-- / --

Mean concentration / mg/L

5.47

7.98

6.10

--

n-Octanol solubility / g/L

0.44

0.64

0.49

--

 

The n-octanol solubility of the test item at 20 °C was determined to be 0.52 g/L (± 0.1 g/L). According to the OECD Guideline 105, the individual results from each of the three flasks should not differ by more than 15%. The relative standard deviation of the three experiments differed by 20 %. However as the water solubility and the n-octanol solubility of the test item were of different orders of magnitudes the influence of this deviation can be neglected.

Calculation of the partition coefficient log POW from the individual solubilities

In the project PS20180018.04rev1 the water solubility of the test item at 20 °C was determined to be 92 g/L. Within this project the n-octanol solubility of the test item at 20 °C was determined to be 0.52 g/L.

The partition coefficient POWof the test item was determined to be: 

log POW = -2.3  

 

Executive summary:

Final result

The partition coefficient (n-octanol/water) of the test item Basic Blue 45 was estimated based on the ratio of the individual solubilities of the test item in water and n-octanol. The solubilities were determined according to the flask method.The shake flask method was not applicable because the present test item was surface active. The HPLC method was not applicable due to the low estimated log POW.

The log POW was found to be:

 

log POW = -2.3 

 

 

Description of key information

Final result

The partition coefficient (n-octanol/water) of the test item Basic Blue 45 was estimated based on the ratio of the individual solubilities of the test item in water and n-octanol. The solubilities were determined according to the flask method.The shake flask method was not applicable because the present test item was surface active. The HPLC method was not applicable due to the low estimated log POW.

The log POWwas found to be:

 

log POW = -2.3 

 

 

Key value for chemical safety assessment

Log Kow (Log Pow):
-2.3
at the temperature of:
20 °C

Additional information