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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:
2010-04-21
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 1
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
GLP compliance:
no
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
4.78
Temp.:
25 °C
pH:
>= 7.62 - <= 8.09
Details on results:
Individual Results and Calculations

As test substance is not expected to be ionisable, the test substance is regarded as being analysed in its neutral form in accordance with the test guidelines.

The determined values of the partition coefficient expressed as their common logarithms fall within a range of ± 0.3 log units as noted in the test guidelines and therefore test accuracy is acceptable.


The determined values of the partition coefficient expressed as their common logarithms fall within a range of ± 0.3 log units as noted in the test guidelines and therefore test accuracy is acceptable.

The applicable range for the shake flask method is 2 < log Kow< 4 (EU method A8). When the concentration of the solute in either phase is not more than 0.01 mol/L, this range may be extended to log Kow up to 5. As the concentrations of test substance do not exceed this value in the test, the shake flask method is an appropriate method to determine log Kow of test substance.

Conclusions:
The partition coefficient of the test substance was 4.78 at 25°C.
Executive summary:

Partition Coefficient in accordance with EU A8 Shake Flask Method, SOP 049.02 Issue No. 4 issued September 2008, Expires September 2010 with quantitative measurement by HPLC, SOP 006.61 Issue 1 issued September 2008, Expires September 2010.

Instrument: Agilent 1200 LC LIMS 1887 (PQ Done: June 2009, PQ Due: June 2010). The partition coefficient of the test substance was determined to be 4.78 at 25°C.

The determined values of the partition coefficient expressed as their common logarithms fall within a range of ± 0.3 log units as noted in the test guidelines and therefore test accuracy is acceptable.

 

Description of key information

The partition coefficient of Isopentyl p-methoxycinnamate is 4.78 at 25°C. 

Key value for chemical safety assessment

Log Kow (Log Pow):
4.78
at the temperature of:
25 °C

Additional information

The partition coefficient of the test substance was measured using EU method A8 (shake flask method) with the aid of quantitative HPLC analysis.

Solutions of the test substance (less than 0.01 M) were prepared, in triplicate, in n-octanol presaturated with Milli Q distilled, deionised water. Aliquots of these 3 solutions were mixed with varying ratios of Milli Q distilled, deionised water presaturated with n-octanol. Each of these solutions was prepared in duplicate. Thus, 6 test solutions were obtained. The solutions were placed in a shaking water bath for 2 h at 25.0±1°C. Each test solution was then centrifuged for 10 min at 2,000 rpm and then left to stand for at least 1 h at 25.0°C±1°C. The layers were separated using disposable pipettes into clean vials. Each layer was analysed quantitatively by HPLC.

The partition coefficients obtained with the 6 test solutions ranged from 4.636 to 4.868. An average partition coefficient of 4.78 was calculated from these results.

As the test substance is not expected to be ionisable, the test substance was considered as being analysed in its neutral form in accordance with the test guidelines.

The determined Log Kow fell within a range of ±0.3 log units. Therefore, as noted in the test guidelines, the accuracy of the test was rated acceptable.

The applicable range for the shake flask method is 2 < log Kow< 4 (EU method A8). When the concentration of the solute in either phase is not more than 0.01 mol/L, this range may be extended to log Kow up to 5. As the concentrations of test substance do not exceed this value in the test, the shake flask method is an appropriate method to determine log Kow of test substance.