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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Studies on adsorption could not be conducted for this substance due to issues with technical feasibility. However, a QSAR has been conducted to estimate the adsorption coefficient for the purpose of the risk assessment. The estimated log Koc ranges from 4.9344 to 11.6046.

Key value for chemical safety assessment

Koc at 20 °C:
1 000 000

Additional information

Due to the UVCB nature of the substance and the fact that accurate analytical methods were not available for the material, the standard tests for adsorption/desorption were not technically feasible. As such, it was considered that a QSAR was necessary to provide the information on adsorption for the risk assessment.

The QSARs were conducted for a component of the material that was considered to be representative. The adsorption coefficient was estimated for this component using KOCWIN v2.00, with estimates based on both molecular connectivity index and an estimated log Kow value. The estimated log Koc from the MCI method was 11.6046 (Koc =>1x1010L/kg) for the linear form of the molecule, and 9.9094 (Koc = 8.117 x107 L/kg) for the cyclic form of the molecule. The estimated log Koc from the octanol:water partition coefficient was 5.3867 (2.436x105L/kg) for the linear form of the molecule, and 4.9344 (8.597x104 L/kg) for the cyclic form of the molecule.

It is likely that these Koc values are underestimates as the material is known to have ionic and cationic properties which would increase the adsorption coefficient. As such, the higher estimated log Koc of 11.6046 is likely to be a more representative value.

All available evidence strongly indicates that the substance will have a very high adsorption coefficient. For the purposes of the risk assessment the Koc has been set to 1x106L/kg. This is the maximum recommended value for the models which have been used for the risk assessment, and as the majority of values calculated by QSAR are close to or in excess of this, it is considered to be the most appropriate value for modelling purposes.

[LogKoc: 6.0]