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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1994-04-20 to 1994-06-02
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
The study was conducted according to an internationally recognised method. Purity is specified, however batch number is not identified, so the isomers composition could not be retrieved from the notifier. Moreover, the result is slightly above the recommended range. Therefore full validation cannot apply.
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
GLP compliance:
yes (incl. certificate)
Remarks:
UK GLP compliance programme (inspected on 31 January 1994 / signed on 16 March 1994)
Type of method:
flask method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
Storage condition of test material: metal canister at 4°C in the dark.
Analytical method:
gas chromatography
Type:
Pow
Partition coefficient:
47 500
Temp.:
22.5 °C
pH:
>= 6.5 - <= 7.3
Key result
Type:
log Pow
Partition coefficient:
4.68
Temp.:
22.5 °C
pH:
>= 6.5 - <= 7.3

The preliminary assessment determined the partition coefficient to be greater than 2500 (log Kow > 3.4).

The peak height of the standard and sample solutions in organic and aqueous phases are detailed in the experimental report.

Sample number Volume of n-octanol (mL) Volume of water (mL) Total weight (mg) n-octanol phase Water phase
Analysed concentration (mg/L) Total weight (mg) Analysed concentration (mg/L) Total weight (mg) pH
1 25 200 62.3 2.57 x 103 64.2 4.38 x 10-2 8.76 x 10-3 7.3
2 25 200 62.3 2.51 x 103 62.6 5.58 x 10-2 1.12 x 10-2 7.0
3 50 200 125 2.54 x 103 127 4.81 x 10-2 9.62 x 10-3 6.7
4 50 200 125 2.58 x 103 129 6.49 x 10-2 1.30 x 10-2 6.6
5 100 200 249 2.46 x 103 246 5.67 x 10-2 1.14 x 10-2 6.6
6 100 200 249 2.49 x 103 249 5.49 x 10-2 1.10 x 10-2 6.5

Temperature = 22.5 +/-0.5°C

pH of n-octanol saturated water = 7.4

Calculations

Sample number n-octanol / water volume ratio Partition coefficient Log10 Kow Mean partition coefficient
1 1:8 5.86 x 104 4.77 5.18 x 104
2 1:8 4.49 x 104 4.65
3 1:4 5.29 x 104 4.72 4.63 x 104
4 1:4 3.98 x 104 4.60
5 1:2 4.33 x 104 4.64 4.44 x 104
6 1:2 4.54 x 104 4.66

Mean = 4.75 x 104, Log10Kow = 4.68, standard deviation = 6.93 x 103

Conclusions:
The substance has potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow >4).
It shall also be taken into account for PBT assessment (log Kow >4.5).
Executive summary:

The partition coefficient of the test substance was measured according to the EU A8 guideline, flask method.

Three ratio were prepared in duplicate, and each phase was analysed by GC. The sample chromatographed with 4 peaks, but only two were integrated for the aqueous phase. The mean result from the 6 samples was retained.

The partition coefficient (log Kow) of the test substance has been determined to be 4.68 (at 22.5°C and pH ca 7).

Endpoint:
partition coefficient
Type of information:
experimental study
Remarks:
Experimental result on the transformation product (C6 isomers) of the registered substance.
Adequacy of study:
supporting study
Study period:
2008-10-21
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Remarks:
The study was conducted according to an internationally recognised method. Substance identification is sufficient for purpose. However some minor restrictions apply due to missing informations.
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
GLP compliance:
no
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
- Storage condition of test material: Refrigerator (between 0 and 10°C under nitrogen)
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
4.33
Temp.:
30 °C
pH:
5.5
Remarks on result:
other: extrapolated

Preliminary estimate: log Kow = 4.01

Standards

 Component  Retention time (min)  log Kow
 injection peak (dead time = t0)  3.08  ---
 Anisole  6.17  2.1
 Ethyl benzoate  7.24  2.6
 Toluene  8.32  2.7
 Ethyl benzene  10.71  3.2
 Isopropylbenzene  13.51  3.7
 Biphenyl  15.99  4.0

slope = 3.0886

intercept = 2.0860

correlation coefficient (r) = 0.9914

Sample

 Component  Retention time (min)  log Kow
 injection peak (dead time = t0)  3.08  ---
 Test substance 19.50  4.33
Conclusions:
The substance has potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow >4).
No difference between isomers.
Executive summary:

The partition coefficient of the test substance was measured according to the OECD 117/EU A8 guideline, HPLC method.

The system was calibrated with 6 reference substances, and the result for the sample was extrapolated from the linear regression.

LogKow of C6 transformation product = 4.33

Endpoint:
partition coefficient
Type of information:
(Q)SAR
Remarks:
QSAR result on the transformation product (C7 isomers) of the registered substance.
Adequacy of study:
supporting study
Study period:
2016-04-01 to 2016-04-04
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
Calculation method using QSAR value. The substance falls into applicability domains of the QSAR model used.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
not applicable
Remarks:
QSAR model
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
not applicable
Remarks:
QSAR model
Principles of method if other than guideline:
A Quantitative Structure-Property Relationship (QSPR) model was used to calculate the n-octanol/water partition coefficient of the test item. This QSPR model has been validated as a QSAR model to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following Guideline for Testing of Chemicals No. 107, "Partition Coeficient (n-octanol/water): Shake Flask Method" and No. 123 "Partition Coeficient (n-octanol/water): Slow Stirring Method”.
See attached QMRF and QPRF.
GLP compliance:
no
Type of method:
calculation method (fragments)
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
4.4

All the required fragment contribution values were available from the iSafeRat® log Kow module. Since no missing fragments were identified, the test substance is within the structural fragment domain of the model.

Conclusions:
The substance has potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow >4).
Executive summary:

A QSAR prediction was performed to assess the partition coefficient of the test item.

This model has been validated to be compliant with the OECD recommendations for QSAR modelling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following Guideline for Testing of Chemicals No. 107, "Partition Coeficient (n-octanol/water): Shake Flask Method" and No. 123 "Partition Coeficient (n-octanol/water): Slow Stirring Method”. The criterion predicted was the log Kow (also known as log Pow).

The determination was performed using a fragment based approach in which the molecule is divided into large and small fragments and each fragment is related to a specific log Kow which may be positive or negative. The final log Kow is determined by simple addition of the fragments.

Calculation was performed from the input SMILES. The substance falls within the applicability domain of the model as demonstrated in the QPRF.

The log Kow of C7 transformation product was determined to be 4.4.

Description of key information

Partition coefficient (log Kow) = 4.68 (experimental) for all isomers.

For the transformation product, log Kow = 4.33 (exp) for the C6 isomers, and 4.4 for C7 (calc).

The log Kow indicates a preliminary alert that substance may have potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow >4).

It shall also be taken into account for PBT assessment.

Key value for chemical safety assessment

Log Kow (Log Pow):
4.68
at the temperature of:
22.5 °C

Additional information

A reliable experimental study, conducted according to a recognized EC method and under GLP, is available. Despite restrictions due to substance identification (isomers composition unknown), it is considered as a key study.

Moreover, as the parent substance is likely to degrade, supporting information is provided also on the log Kow of the transformation products, which are the relevant species for the environmental risk assessment.

The worst-case value, i.e. parent substance, is retained as key data for purpose of CSA.