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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:
03 July 2017 to 04 July 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Version / remarks:
2004
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
5.59
Temp.:
20 °C
Remarks on result:
other: ± 0.01
Key result
Type:
Pow
Partition coefficient:
389 477
Temp.:
20 °C
Remarks on result:
other: ± 2749
Details on results:
PRELIMINARY TEST
- The preliminary test at room temperature showed, that the octanol solubility of the test material was between 24.0 and 43.2 g/L. The observations of the preliminary test are summarised in Table 2.
- With the water solubility of < 9.54 mg/L (determined in the preliminary test of another study) and the solubility in octanol of 24.0 to 43.2 g/L, determined from this preliminary test, the partition coefficient can be estimated to be between 3.4 and 3.7.
- For the determination of the log Pow at this value the HPLC method is recommended and carried out.

MAIN TEST
- After the measurements of the retention times tR the log k values of the reference materials were plotted as a function of their log Pow values. The partition coefficient of the test material was obtained by interpolation of the calculated capacity factor on the calibration graph of the reference materials.
- The first measurement and the linear regression of the calibration graph leads to an equation for the log Pow of: log Pow = 4.486 · log k + 3.604
Correlation coefficient r = 0.9897
- The second measurement and the linear regression of the calibration graph leads to an equation for the log Pow of: log Pow = 4.435 · log k + 3.621
Correlation coefficient r = 0.9889
- With the determined regression coefficients a and b, the log Pow of the test material can be calculated for both measurements.
- The test material has a partition coefficient at 20 °C of log Pow = 5.59 ± < 0.01

Table 2: Retention times of the test material

Test material

tR

k

log k

log Pow

Pow

1st measurement

8.340

2.775

0.443

5.59

391421

2nd measurement

8.345

2.777

0.444

5.59

387534

mean value

5.59

389477

standard deviation

< 0.01

2749

Conclusions:
Under the conditions of this study the test material has a partition coefficient at 20 °C of log Pow = 5.59 ± < 0.01 (Pow = 389477).
Executive summary:

The partition coefficient of the test material was assessed in accordance with the standardised guidelines OECD 117 and EU Method A.8 under GLP conditions.

The partition coefficient of the test material was estimated by performance of preliminary tests and using the equation:

Pow = (cn–octanol) / cwater.

The preliminary test at room temperature showed, that the octanol solubility of the test material was between 24.0 and 43.2 g/L. With the water solubility of < 9.54 mg/L (determined in the preliminary test of another study) and the solubility in octanol of 24.0 to 43.2 g/L, determined from this preliminary test, the partition coefficient can be estimated to be between 3.4 and 3.7. For the determination of the log Pow at this value the HPLC method is recommended and was therefore carried out. The main test was performed by isocratic elution with acetonitrile/water in a ratio of 75: 25 %.

After the measurements of the retention times tR the log k values of the reference materials were plotted as a function of their log Pow values. The partition coefficient of the test material was obtained by interpolation of the calculated capacity factor on the calibration graph of the reference materials.

Under the conditions of this study the test material has a partition coefficient at 20 °C of log Pow = 5.59 ± < 0.01 (Pow = 389477).

Description of key information

Under the conditions of this study the test material has a partition coefficient at 20 °C of log Pow = 5.59 ± < 0.01 (Pow = 389477).

Key value for chemical safety assessment

Log Kow (Log Pow):
5.59
at the temperature of:
20 °C

Additional information

The partition coefficient of the test material was assessed in accordance with the standardised guidelines OECD 117 and EU Method A.8 under GLP conditions.

The partition coefficient of the test material was estimated by performance of preliminary tests and using the equation:

Pow = (cn–octanol) / cwater.

The preliminary test at room temperature showed, that the octanol solubility of the test material was between 24.0 and 43.2 g/L. With the water solubility of < 9.54 mg/L (determined in the preliminary test of another study) and the solubility in octanol of 24.0 to 43.2 g/L, determined from this preliminary test, the partition coefficient can be estimated to be between 3.4 and 3.7. For the determination of the log Pow at this value the HPLC method is recommended and was therefore carried out. The main test was performed by isocratic elution with acetonitrile/water in a ratio of 75: 25 %.

After the measurements of the retention times tR the log k values of the reference materials were plotted as a function of their log Pow values. The partition coefficient of the test material was obtained by interpolation of the calculated capacity factor on the calibration graph of the reference materials.

Under the conditions of this study the test material has a partition coefficient at 20 °C of log Pow = 5.59 ± < 0.01 (Pow = 389477).