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Adsorption / desorption

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Description of key information

The adsorption desorption coefficients of MAPDA-ABS salt  was calculated by US EPAs software EPIWIN. The results indicates the log Koc to be 2.01 for the ionized species and 4.09 for the unionized species. 

Key value for chemical safety assessment

Koc at 20 °C:

Additional information

The calculated estimates should be treated with some caution and may be prone to error. Quantitative Structure Activity Relationships (QSAR'S) detailed in the Technical Guidance Document (TGD) may be unreliable and therefore were not used in the estimation of adsorption coefficient. Although correction factors can be applied, it has been shown that QSAR models can significantly underestimate the adsorption coefficient of cationic substances. However, PCKOCWIN does use the experimentally determined partition coefficient value for validation of the program so for the anionic component, the estimate is considered to be more reliable. Due to the caveats involved with the program used, the calculation was performed for the ionised and unionised species of both components.

The test item is a salt and as such the components of the test item will always be present in their ionised forms. As a consequence of this, the overall result quoted will be that of the ionised species.