4-hydroxycoumarin

Partition coefficient

Link to relevant study record(s)

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 P_ow: 206

log₁₀ P_ow:2.31

P_ow 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.