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Physical & Chemical properties

Partition coefficient

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Description of key information

Log Pow > 10 (QSAR models: VEGA / ALogP version 1.0.0; EPI Suite / KOWWIN version 1.68, SPARC v4.6)

Key value for chemical safety assessment

Additional information

Explanation of the results

For the three evaluated components of the substance, the Log Pow values as estimated by the VEGA/ALogP, EPI Suite/KOWWIN and SPARC models are reported.

Evaluation of component

VEGA / ALogP

EPI Suite / KOWWIN

SPARC

SU_1RU

11.83

13.55

11.9

SU_3RU

21.61

25.3

19.61

SU_4RU

26.49

31.18

22.87

 

Discussion

Based on the applicability domain (AD) evaluation performed by the VEGA, as well as on the molecular weights and predicted Log Pow values, the three components are not fully compliant with the applicability domain of the VEGA / ALogP model.

A similar situation applies also to the EPI Suite / KOWWIN model: the molecular weights of the evaluated molecules exceed the range defined by the training set and some of the fragments used for calculation exceed the maximum number of instances present in the training set.

The similarity of the most similar substances identified by VEGA is low; the evaluation of the performances of Meylan and ALogP models of these molecules is therefore deemed to be not useful to support the predicted values for the target ones.

SPARC has been designed and parameterized to be applicable to any organic chemical structure. The partition coefficient model validation, performed on a dataset of 698 molecules, proved that the model can be used to provide reliable estimations. It is however not possible to perform a clear evaluation of the model’s applicability domain.

The three target molecules are characterized by very long carbon chains and high molecular weights (> 600). Based on these characteristics high Log Pow values could be expected. The models provided similar estimations for the three components, with Log Pow values always > 10.

 

Conclusion

Considering the results obtained for the representative components, using three different (Q)SAR models, a Log Pow value > 10 can be safely estimated for the target substance.

Consideration on the different grades

The components of the UVCB substance are essentially composed by the same subunits: a "starting unit" and one or more "repeated unit". The two grades of the substance differ by the presence of "bigger" components in Grade Two.

As the Log Pow of the smaller component is estimated to be > 10, the final result is considered as valid for both grades.