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Environmental fate & pathways

Adsorption / desorption

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Description of key information

As the determination of adsorption coefficient was not possible by using standard HPLC methods (OECD guideline N°121), the adsoption coefficient was determined by modelling. A Sewage treatment plants usally operate at pH values  between 5.5 and 7.5, testing for the adsorption coefficient is usually conducted at approximately this pH range. However, at this range, the amine groups of the test item would be in their ionized form. Experience has shown that positively charged nitrogen species can interact with the column stationary phase by forces other than partitioning. This was found to be the case with this test article as it was found to be fully retained by the CN column. This retention was considered to be due to interactions with the stationary phase by forces other than partitioning. Therefore, due to the unsuitability of the HPLC method, an estimate of the adsorption coefficient was performed using specialist chemical estimation software.
Log Koc estimated by the molecular conductivity index method using software program KOCWIN v2.00 (US EPA, February, 2009) gave a value of 4.47.
Log Koc estimated from the Log Kow using the same program gave a value of 4.0572. The Koc retained for chemical safety assessement was 4.06.

Key value for chemical safety assessment

Koc at 20 °C:
11 481.54

Additional information