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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:
2002
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
GLP compliance:
yes
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 62630012
- Expiration date of the lot/batch: 01.11.2002
- Purity: 94.0 %

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature in the dark
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
> 6.2
Temp.:
22 °C
pH:
10.5
Conclusions:
The results of the Calculation method and the HPLC method were not in agreement. Since the HPLC method is a more accurate method than the Calculation method, the result of the HPLC method is reported as the partition coefficient (n-octanol/water), Pow, of Phytosphingosine. The partition coefficient (n-octanol/water), Pow, of Phytosphingosine is >1.6 x 10^6 (log Pow > 6.2).
Executive summary:

Main test

The mobile phase was 60/40 (v/v) acetonitrile/Milli-Q water, and a refractive index detector was used. The column oven temperature was set to 22.0°C during the test. HPLC chromatograms of the Phytosphingosine test solution, the test substance blank solution (methanol) and the 2,4-DDT reference solution are provided. In the chromatograms of the 1840 mg/L Phytosphingosine test solution, which were recorded for 90 minutes, no test substance peak was observed. Under the same chromatographic conditions, the retention time of 2,4-DDT (log P. = 6.2) was 57.2 minutes. It was assumed that Phytosphingosine elutes after the reference substance 2,4 -DDT. The column oven temperature was set to 22.0°C during the test.

Additional test

In order to show that the test substance can be passed through the HPLC column and can be detected using a refractive index detector, a second mobile phase (60/40/0.05 (v/v/v) acetonitrile/Milli-Q water/trifluoracetic acid) was used. Methanol, the 2,4 -DDT solution, the test solution (in duplicate), the 2,4-DDT solution and methanol were injected using this mobile phase. One large test substance peak at a retention time of 3.49 minutes was observed in the chromatograms of the 1836 mg/L Phytosphingosine test solution. Therefore, it was concluded that at neutral pH, Phytosphingosine elutes

after the reference substance with known log P of 6.2. Hence, the log Pow of Phytosphingosine is > 6.2 (P > 1.6 x 10^6). Under the conditions used, a non-ionised substance will elute later than an ionised one.

Because Phytosphingosine is ionised at neutral pH and non-ionised at pH 10.5, it was concluded that the test substance will not elute before the reference substance and that log Pow of Phytosphingosine is also > 6.2 (P ow > 1.6 x 10^6) at pH 10.5.

Description of key information

The results of the Calculation method and the HPLC method were not in agreement. Since the HPLC method is a more accurate method than the Calculation method, the result of the HPLC method is reported as the partition coefficient (n-octanol/water), Pow, of Phytosphingosine. The partition coefficient (n-octanol/water), Pow, of Phytosphingosine is >1.6 x 10^6 (log Pow > 6.2).

Key value for chemical safety assessment

Log Kow (Log Pow):
6.2
at the temperature of:
22 °C

Additional information