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Diss Factsheets

Administrative data

partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 2005
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
EU Method A.8 (Partition Coefficient)
, see "Principles of method if other than guideline"
Principles of method if other than guideline:
The test material was known to primarily be a complex mixture of alkanes and therefore a majority of the components were not anticipated to absorb in the ultraviolet region. The test material was therefore initially investigated using a refractive index (RI) detector. However, no test material components were observed to elute prior to the retention time of DDT. Additionally as no components were successfully eluted from the HPLC column using isocratic conditions maintaining a minimum of 25% water in the mobile phase as required by EEC Method A.8, it was necessary to introduce a gradient increase in the solvent content on the mobile phase to 100% methanol. This requirement eliminated the viability of the RI detection method as the detector baseline is adversely affected by the continuing shift in the refractive index of the mobile phase caused by the gradient. Therefore the sample was monitored in the far UV region and the elution of the test material confirmed by fraction collection and subsequent GC analysis. The retention time limit value used for the calculation of the sample partition coefficient result represents the start of the amended 100% methanol mobile phase. All components of the test material were demonstrated to elute after this time and shared a common partition coefficient value, that of greater than the highest calibration standard.
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC method
Partition coefficient type:

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
main general molecular formula: CnH(2n+2)
2,2,3,4,4,5,6-heptamethylheptane; 2,2,8-trimethyltetradecane; 2,2-dimethyldodecane; 2,2-dimethyltetradecane; 2-methyltetradecane; 3,5,7-triethyldecane; 4-ethyldodecane; 4-propyldodecane; 5,5-dipropylnonane; 5,7-dimethyl-4-propylundecane; 5-butyl-5-propyldecane; 5-butyl-5-propylnonane; 5-ethyl-5-propylnonane; 5-ethyl-7-methyl-4-propylundecane; 5-propyltridecane; 6-butyl-6-methyldodecane; 6-butyldodecane; 6-butylundecane; 7-methyl-4-propylundecane; 8-methyl-5-propyltridecane; 9-butyl-6-propylhexadecane; heptadecane; hexacosane; hexadecane; octane; pentadecane; tetradecane
Details on test material:
- Name of test material (as cited in study report): Distillates (Fischer-Tropsch), C8-26 branched and linear
- Substance type: Organic
- Physical state: Clear colorless liquid
- Analytical purity: 100%
- Impurities (identity and concentrations): Information not available
- Composition of test material, percentage of components: Information not available
- Isomers composition: Information not available
- Purity test date: Information not available
- Lot/batch No.: Information not available
- Expiration date of the lot/batch: Information not available
- Stability under test conditions: Stable under normal temperature and pressure
- Storage condition of test material: Room temperature, in the dark

Study design

Analytical method:
gas chromatography
high-performance liquid chromatography

Results and discussion

Partition coefficient
log Pow
Partition coefficient:
> 6.5
40 °C
ca. 7
Details on results:
The limit value of 6.5 is based on the retention time of the reference substance (DDT).

Any other information on results incl. tables


1) Preliminary estimate

The preliminary estimate of the partition coefficient was calculated using the following equation:

POWestimate = solubility of the test material in n-octanol / solubility of the test material in water (Equation 1)

2) Capacity factor

The capacity factor was determined using the following equation:

k = (tr-t0)/t0 (Equation 2)


k = capacity factor

tr= retention time (min)

t0= dead time (min)


1) Preliminary estimate

- approximate solubility in n-octanol: >65.4% (w/w)

- approximate solubility in water: <5.32 x 10-3% (w/w)

- approximate Pow: >1.23 x 104

- log10POW>4.09

2) Definitive test

a) Calibration

The retention times of thiourea and the retention times, capacity factors (k) and log10POWvalues for the reference standards are shown in the following two tables:
Dead Time Retention Time (min) Mean Retention Time (min)
Injection 1 Injection 2
Thiourea 1.851 1.854 1.853

Standard Retention Time (min) Mean Retention Time (min) Capacity factor (k) Log10k Log10POW
Injection 1 Injection 2
Benzene 3.085 3.087 3.086 0.666 -0.177 2.1
Toluene 3.696 3.697 3.697 0.995 -2.00 x 10-3 2.7
Naphthalene 4.033 4.035 4.034 1.178 7.10 x 10-2 3.6
Phenanthrene 5.567 5.564 5.566 2.004 0.302 4.5
Triphenylamine 11.005 11.034 11.020 4.984 0.694 5.7
DDT 15.544 15.509 15.527 7.381 0.868 6.5

A calibration curve was constructed from the retention time data of the thiourea and reference standard solutions. The capacity factors (k) for the reference standards were calculated using equation 2 (see above).

Logic POW-values of the reference standards are those quoted in Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

b) Partition coefficient of sample

The retention times, capacity factors and log10POW-values determined for the sample are shown in the following table:
Injection Retention Time (min) Capacity factor (k) log10k log10POW
1 >17.5 >8.447 >0.927 >6.50
2 >17.5 >8.447 >0.927 >6.50

The capacity factor was calculated using Equation 2 (see above) and the log10POW-value determined with reference to the calibration curve.

3) Summary

- Mean log10POW: >6.50

- Partition coefficient: >3.16 x 106

Applicant's summary and conclusion

partition coefficient: log10Pow > 6.50 (at 40°C and pH 7)
Executive summary:

According to EU Method A.8 the partition coefficient was determined using the HPLC method. To allow detection of the test material, fractions of eluent were collected from the HPLC instrument for analysis by gas chromatography (GC). The partition coefficient of the test material has been determined to be greater than 3.16 x 106, log10POW >6.50 (arithmetic mean of two determinations at 40°C and pH7). The limit value of 6.5 is based on the retention time of the reference substance (DDT).