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Physical & Chemical properties

Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experiment start date - 06 November 2020; Experiment end date - 22 January 2021.
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 - Shake Flask Method)
Deviations:
no
GLP compliance:
yes
Type of method:
flask method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
Identification: 4-Hydroxycoumarin
CAS Number: 1076-38-6
Appearance/Physical State: Beige powder
Batch Number: HCN20002
Purity: > 99%
Expiry Date: 26 September 2022
Storage Conditions: Room temperature, in the dark
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
2.31
Temp.:
21.2 °C
pH:
1.4
Details on results:
Preliminary Estimate: The log Pow was calculated to be 0.63.

The partition coefficient determined for each flask is shown in the following table:

Flask

Organic/Aqueous Volume Ratio

Partition

Coefficient

Log10 Pow

Mean

Partition Coefficient

1

 

1:1

209

2.32

 

202

2

196

2.29

3

 

1:2

205

2.31

 

200

4

195

2.29

5

 

2:1

201

2.30

 

215

6

230

2.36

Mean Pow: 206

log10 Pow:2.31

Pow standard deviation :12.8

Validation

Organic phase: The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 5 to 15 mg/L. The results were satisfactory with a correlation coefficient (r) of 0.9999 being obtained.

Aqueous phase: The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 1.0 to 3.0 mg/L. The results were satisfactory with a correlation coefficient (r) of 0.9986 being obtained.

Conclusions:
The partition coefficient of the test item at pH 1.4 has been determined to be 206 at 21.2 ± 0.5 °C, log10 Pow 2.31. The corrected partition coefficient (Dow) of the test item has been calculated to be 0.210, log10 Dow -0.677 at pH 7.
Executive summary:

The determination was carried out by the shake-flask method, using a procedure designed to be compatible with Method A.8 Partition Coefficient of Commission Regulation (EC) No. 440/2008 of 30 May 2008 and Method 107 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.

The concentration of test item in the sample solutions was determined by high performance liquid chromatography (HPLC). The determination of partition coefficient was performed using the shake-flask method. This was due to the expected log10 Pow obtained in the preliminary assessment, but also because testing using the HPLC-method at a pH below 2 would be impractical due to the corrosive effect of the strongly, acidic pH on the stationary phase of the column packing and also on the metal column itself.

The n-octanol saturated water was adjusted to pH < 2, to ensure the test item was partitioned in its non-ionized form, as requested by the EU and OECD guidelines.

The partition coefficient of the test item at pH 1.4 has been determined to be 206 at 21.2 ± 0.5 °C, log10 Pow 2.31. The corrected partition coefficient (Dow) of the test item has been calculated to be 0.210, log10 Dow -0.677 at pH 7.

Description of key information

The partition coefficient of the test item at pH 1.4 has been determined to be 206 at 21.2 ± 0.5 °C, log10 Pow 2.31. The corrected partition coefficient (Dow) of the test item has been calculated to be 0.210, log10 Dow -0.677 at pH 7.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.31
at the temperature of:
21.2 °C

Additional information

The determination was carried out by the shake-flask method, using a procedure designed to be compatible with Method A.8 Partition Coefficient of Commission Regulation (EC) No. 440/2008 of 30 May 2008 and Method 107 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.

The concentration of test item in the sample solutions was determined by high performance liquid chromatography (HPLC). The determination of partition coefficient was performed using the shake-flask method. This was due to the expected log10 Pow obtained in the preliminary assessment, but also because testing using the HPLC-method at a pH below 2 would be impractical due to the corrosive effect of the strongly, acidic pH on the stationary phase of the column packing and also on the metal column itself.

The n-octanol saturated water was adjusted to pH < 2, to ensure the test item was partitioned in its non-ionized form, as requested by the EU and OECD guidelines.

The partition coefficient of the test item at pH 1.4 has been determined to be 206 at 21.2 ± 0.5 °C, log10 Pow 2.31. The corrected partition coefficient (Dow) of the test item has been calculated to be 0.210, log10 Dow -0.677 at pH 7.