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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
March 22 2017
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
Justification for type of information:
iSafeRat® High-Accuracy-Quantitative Structure-Activity Relationship (HA-QSAR) based on a holistic approach for predicting physicochemical and ecotoxicological endpoints: Octanol-water partition coefficient

1. SOFTWARE
iSafeRat® HA-QSAR toolbox v2.3

2. MODEL (incl. version number)
iSafeRat® holistic HA-QSAR v1.7

3. IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES code (see attached QPRF of each constituent)

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF

5. APPLICABILITY DOMAIN
See attached QPRF

6. ADEQUACY OF THE RESULT
See attached QPRF
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Version / remarks:
QSAR
Deviations:
not applicable
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Version / remarks:
QSAR
Deviations:
not applicable
Principles of method if other than guideline:
A Quantitative Structure-Property Relationship (QSPR) model was used to calculate the n-octanol/water partition coefficients 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 the 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 contribution which may be positive or negative. The final log KOW is determined by simple addition of the fragments. The predicted log KOW values have been validated against high quality experimental studies generally using the shake-flask method but slow-stir values have been used when available. The results are considered to be as accurate as those from a good quality OECD 107 or 123 study.
GLP compliance:
no
Type of method:
other: QSAR
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
4.8
Temp.:
25 °C
pH:
>= 0 - <= 14

No pH-dependency anticipated from structure (hydrocarbon, no ionisable feature).

Conclusions:
The log KOW of test item was predicted as 4.8 at 25°C.
The substance has potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow >4).
Executive summary:

A Quantitative Structure-Property Relationship (QSPR) model was used to calculate the noctanol/water partition coefficients 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 the 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 test item is within the applicability domain (MW, descriptors).

Finally the logKOW of test item has been determined to be between 4.8 at 25°C.

Description of key information

The log KOW of test item was predicted as 4.8 at 25°C. (estimated by QSAR)

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

Key value for chemical safety assessment

Log Kow (Log Pow):
4.8
at the temperature of:
25 °C

Additional information

No study was conducted on the test item itself.

The partition coefficient of the test item was estimated using the recommended QSAR model iSafeRat®, based on Regression Fragment-based Approach’(RFA) method and are used in a Weight of Evidence approach. The substance is within the applicability domain (MW, descriptors).

The log KOW of test item was predicted as follows: 4.8 at 25°C.