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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
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)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
- Name of test material (as cited in study report): Composite Sample No. 7, Anthracene Oil < 50 ppm B[a]P
- Analytical purity: not applicable (UVCB)
- Storage condition of test material: Room temperature (20 ± 5 °C)
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
>= 4.43 - <= 5.2
Temp.:
25 °C
pH:
6 - 7
Remarks on result:
other: 5 major peaks (peak areas > 5%) were observed. Log Pow values reported cover the range from the first to the last of these peaks
Key result
Type:
log Pow
Partition coefficient:
4.614
Temp.:
25 °C
pH:
6 - 7
Remarks on result:
other: weighted average
Key result
Type:
log Pow
Partition coefficient:
4.428
Temp.:
25 °C
pH:
6 - 7
Remarks on result:
other: peak 10 (40.3 %)
Key result
Type:
log Pow
Partition coefficient:
4.579
Temp.:
25 K
pH:
6 - 7
Remarks on result:
other: peak 11 (16.1 %)
Key result
Type:
log Pow
Partition coefficient:
4.971
Temp.:
25 °C
pH:
6 - 7
Remarks on result:
other: peak 14 (6.4 %)
Key result
Type:
log Pow
Partition coefficient:
5.129
Temp.:
25 °C
pH:
6 - 7
Remarks on result:
other: peak 15 (5.5 %)
Key result
Type:
log Pow
Partition coefficient:
5.199
Temp.:
25 °C
pH:
6 - 7
Remarks on result:
other: peak 16 (5.0 %)

Dead time of the HPLC system was 1.379 ± 0.004 min.

Retention times of reference substances were between 3.150 min (benzene) and 35.689 min (benzo[a]pyrene). Standard deviation for the six repeated HPLC runs were calculated to range from 0.0 (benzene) to 0.065 (benzo[a]pyrene). Capacity factors were computed between 1.2843 (benzene) and 24.8803 (benzo[a]pyrene). Regression equation was determined as log K = 0.2957 log Pow - 0.5196 (r² = 0.9827).

The HPLC chromatogram of the test substance showed 25 peaks with retention times between 3.56 and 33.28 min. Five peaks with relative areas > 5 % were used for evaluation. They contribute approx. 79 % of the total HPLC area under test conditions. Capacity factors for these peaks extended from 6.16 (log K 0.79) to 10.41 (log K 1.017). Log Pow values were calculated using the regression equation above.

 

Peak

Parameter

Criterion

Found

Assessment

10

Range of determined log Pow values

< 0.1

0.003

valid

Value within Range of Reference Items

2.10 - 6.35

4.428

valid

11

Range of determined log Pow values

< 0.1

0.003

valid

Value within Range of Reference Items

2.10 - 6.35

4.579

valid

14

Range of determined log Pow values

< 0.1

0.003

valid

Value within Range of Reference Items

2.10 - 6.35

4.971

valid

15

Range of determined log Pow values

< 0.1

0.003

valid

Value within Range of Reference Items

2.10 - 6.35

5.129

valid

16

Range of determined log Pow values

< 0.1

0.003

valid

Value within Range of Reference Items

2.10 - 6.35

5.199

valid

 

As the evaluated peaks/substances contribute to 77.8% of the total area in the test substance chromatogram, these results are estimated to satisfactorily represent the total test substance. The log Pow of the test substance is therefore stated as range of 4.43 - 5.20. Based on their retention times, peaks 5, 10, 14, and 20 were allocated to the substances naphthalene, phenanthrene, fluoranthene, and chrysene.

Note: The GC analysis shows that two of the key constituents (Phenanthrene and Fluoranthene) account for about 32 %, while the total of relevant key components amounts to about 45 – 50 % of the injected sample. The composition confirms the dominant constituents from fluorene to fluoranthene/pyrene cover this Pow range.

Conclusions:
Log Pow for anthracene oil (Anthracene Oil < 50 ppm B[a]P, AOL) was determined by the HPLC method following OECD/EU test guideline 117/A.8. In the chromatogram of the test substance, 25 peaks were separated under test conditions. For five peaks, the relative peak area was greater than 5%, contributing to approx. 79% of the total area in the chromatogram. Retention time evaluation of these peaks according to the procedure of the test guideline resulted in log Pow values from 4.43 to 6.2 (first and last peak)s. This range of log Pow values is assessed to adequatly represent the octanol water partition coefficient of the test substance.
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Studies comparable to guideline studies, based on accepted scientific principles
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Version / remarks:
method used by Miller et al. (reference 1)
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Version / remarks:
method used by de Maagd et al. (reference 2)
Deviations:
yes
Remarks:
Study followed the principles of the slow stirring method (but date of study before publication of TG). Log Pow were measured for several components (PAH) combined in one solution; only single experiments but with two different substance concentrations
GLP compliance:
no
Type of method:
other: flask method (reference 1), slow-stirring method (reference 2)
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
The following PAH as constituents of anthracene oil (composite sample 07) (anthracene oil with < 50 ppm BaP, AOL) are included in the evaluation of log Pow.

CAS-No. Concentration [%w/w]*
====================================================
Acenaphthene 83-32-9 3.5 - 4 (reference 1)
Fluorene 86-73-7 6.5 - 8 (reference 1)
Phenanthrene 85-01-8 26 - 31 (reference 1 and reference 2)
Anthracene 120-12-7 6 - 7 (reference 1 and reference 2)
Fluoranthene 206-44-0 6 – 7.5 (reference 2)
Pyrene 129-00-0 ~ 3 (reference 1)
Chrysene 218-01-9 -- (reference 2)
====================================================
* Concentrations in anthracene oil CS 07 (GC analysis)

Reference 1: Test materials were obtained from Aldrich, K & K Rare and Fine Chemicals, and from Eastman Kodak Co. They were of the highest available commercial quality.
Reference 2: Test materials were obtained from Sigma Chemical Company, St. Louis, MO, USA and had a purity ≥ 95 % or from Aldrich Chemical Company, Steinheim, Germany (fluoranthene, purity 98 %).
Analytical method:
gas chromatography
other: GLP liquid chromatography coupled to UV-absorbance/fluorescence detection system
Key result
Type:
log Pow
Partition coefficient:
ca. 4 - ca. 5.2
Temp.:
25 °C
pH:
ca. 7 - ca. 7.5
Key result
Type:
log Pow
Partition coefficient:
4.18
Temp.:
25 °C
Remarks on result:
other: test substance fluorene - reference 1
Key result
Type:
log Pow
Partition coefficient:
4.57
Temp.:
25 °C
Remarks on result:
other: test substance phenanthrene - reference 1 and reference 2
Key result
Type:
log Pow
Partition coefficient:
4.54
Temp.:
25 °C
Remarks on result:
other: test substance anthracene - reference 1; reference 2: log Pow = 4.68
Key result
Type:
log Pow
Partition coefficient:
5.23
Temp.:
25 °C
Remarks on result:
other: test substance fluoranthene - reference 2
Details on results:
The range of approx. 60 % of components of anthracene oil (< 50 ppm BaP) is between log Pow of approx. 4 and 5.2 with the estimated average of 4.5 - 4.6, best represented by phenanthrene.

Summary of n-octanol-water partition coefficients (as log Pow) for a range of PAH covering key components of anthracene oil (< 50 ppm BaP)

 

Substance

CAS-No.

log Pow

Source

Acenaphthene

83-32-9

3.92

Miller et al. 1985

Fluorene

86-73-7

4.18

Miller et al. 1985

Phenanthrene

85-01-8

4.57

Miller et al. 1985
de Maagd et al. 1998

Anthracene

120-12-7

4.54
4.68

Miller et al. 1985
de Maagd et al. 1998

Fluoranthene

206-44-0

5.23

de Maagd et al. 1998

Pyrene

129-00-0

5.18

Miller et al. 1985

Chrysene

218-01-9

5.81

de Maagd et al. 1998

 

The substances labelled grey are relevant constituents present in anthracene oil. Their log Pow characterise the log Pow of anthracene oil and cover a range from ca. 4.2 to ca. 5.2.

 

Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH

The source test materials are individual polycyclic aromatic hydrocarbons (PAH). Depending on size/molecular weight and state of condensation, physico-chemical and environmental properties can be different.
The target substance anthracene oil (< 50 ppm BaP, AOL) is composed of a broad range of PAH differing in size and degree of condensation. Physico-chemical and environmental properties of AOL will be characterised by the range of PAH that are components of AOL.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source chemicals are individual PAH. The specific analytical purity of individual chemicals is only specified for some of them (≥ 95 %). But all test materials are obtained from commercial sources and, if the analytical purity is not specified, they are described as being of the highest available commercial quality. Hence, the results reported are unambiguously related to the individual test substances.
The target material anthracene oil is a UVCB substance obtained from the distillation of coal tar having an approximate distillation range of 300 °C to 400 °C. It consists of a complex mixture of polycyclic aromatic hydrocarbons ranging in size from three- to four-ring fused aromatic systems. Major constituents are phenanthrene, anthracene, and fluoranthene amounting to approx. 40 - 60 % with carbazole as minor constituent (typical concentration ca. 4 %). Fraction of the 16 EPA PAH in GC analysis is ca. 50 to 60 % with benzo[a]pyrene < 50 ppm.

3. ANALOGUE APPROACH JUSTIFICATION
Properties of the target substance anthracene oil relevant for environmental fate and distribution will be determined by the properties of the PAH that are constituents of AOL. Under environmental conditions or during processing of the target substance, environmentally available or volatile components of AOL can be released. These will be PAH (see above). Distribution properties of these PAH will be specific for the environmental behaviour of AOL. Therefore, it is justified to use data determined for individual PAH that are constituents of AOL to characterise the environmental behaviour of anthracene oil itself.
Reason / purpose for cross-reference:
read-across source
Principles of method if other than guideline:
Read-across to preceding entry:
Source test material: polycyclic aromatic hydrocarbons (PAH), generic mixture;
Reference: Miller et al. 1985, de Maagd et al. 1998
Key result
Type:
log Pow
Partition coefficient:
ca. 4 - ca. 5.2
Temp.:
25 °C
pH:
ca. 7 - ca. 7.5
Remarks on result:
other: the test results of the source substances are adopted as weight of evidence for the target substance anthracene oil
Key result
Type:
log Pow
Partition coefficient:
4.18
Temp.:
25 °C
Remarks on result:
other: test substance fluorene
Remarks:
the test result of the source substance is adopted as weight of evidence for the target substance anthracene oil
Key result
Type:
log Pow
Partition coefficient:
4.57
Temp.:
25 °C
Remarks on result:
other: test substance phenanthrene
Remarks:
the test result of the source substance is adopted as weight of evidence for the target substance anthracene oil
Key result
Type:
log Pow
Partition coefficient:
4.54
Temp.:
25 °C
Remarks on result:
other: test substance anthracene; supplementary value: log Pow = 4.68
Remarks:
the test result of the source substance is adopted as weight of evidence for the target substance anthracene oil
Key result
Type:
log Pow
Partition coefficient:
5.23
Temp.:
25 °C
Remarks on result:
other: test substance fluoranthene
Remarks:
the test result of the source substance is adopted as weight of evidence for the target substance anthracene oil
Details on results:
The range of approx. 60 % of components of anthracene oil (< 50 ppm BaP) is between log Pow of approx. 4 and 5.2 with the estimated average of 4.5 - 4.6, best represented by phenanthrene.
Conclusions:
Log Pow values of anthracene oil constituents extent from ca. 4 to ca. 5.2. This range of log Pow values characterises the environmental distribution properties of anthracene oil. The log Pow value of the marker substance phenanthrene (5.47) is considered to represent adequately the mean partition properties of the UVCB anthracene oil.

Description of key information

A chemical analytical study (OECD 117) with anthracene oil (CCSG composite sample 07, CAS No. 90640-80-5) (anthracene oil with < 50 ppm BaP, AOL) confirms the result from a previous literature search: Relevant log Pow values range from ca. 4.4 to ca. 5.2, based on HPLC analysis.

Key value for chemical safety assessment

Log Kow (Log Pow):
4.57
at the temperature of:
25 °C

Additional information

In a standard study using the HPLC method (OECD 117), anthracene oil (CCSG composite sample 07, CAS No. 90640 -80 -5) was poorly soluble in the common solvent mixture (methanol/water, here: 75+25) and had to be dissolved in tetrahydrofuran (THF) before analysis. Five peaks with relative areas > 5 % were used for evaluation (peak 10, 11, 14, 15, 16). They contribute 77.3 % of the total HPLC area under test conditions. Log Pow values were determined to extend from ca. 4.43 to ca. 5.2. Therefore, the log Pow of the test substance is stated as range of 4.43 - 5.2. The weighted average value was 4.61.

Based on their retention times, peaks 5, 10, 14, and 20 were allocated to the substances naphthalene, phenanthrene, fluoranthene, and chrysene.

Note: The GC analysis shows that two of the key constituents (phenanthrene and fluoranthene) account for about 32 %, while the total of both substances amounts to about 47 % (peak area) in the HPLC analysis.

When evaluating independently determined log Pow values of PAH components of AOL, the range of log Pow values was found to coincide with the log Pow range determined in the HPLC analysis (from ca. 4.2 for fluorene to ca. 5.2 for fluoranthene and chrysene, Miller et al. 1985/de Maagd et al. 1998). The analysis confirms that the dominant constituents of AOL from fluorene to fluoranthene/pyrene cover the log Pow range observed in the HPLC study.

The log Pow value of 4.57, related to the marker substance phenanthrene (Miller et al. 1985/de Maagd et al. 1998), is considered to sufficiently represent the mean partition properties of the UVCB substance anthracene oil and is used for the chemical safety assessment.