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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
key study
Study period:
Testing was conducted between 31 August 2005 and 18 October 2005.
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Qualifier:
no guideline required
Principles of method if other than guideline:
Sewage Treatment plants usually operate between pH 5.5 and 7.5. For this reason, testing is usually carried out within this pH range. However, at this pH, the quaternary amine group present in the test material would be in its ionised form. Experience has shown that positively charged nitrogens can interact with the stationary phase of the column by forces other than partitioning. This was to be the case for this material in method development investigations, The test material could not be eluted from the analytical colurnn.

More importantly, the test material was shown to be significantly surface active in the partition coefficient test. The determination of Adsorption coefficient by HPLC estimation is not suitable for surface active materials.

Quantitive Structure Activity Relationships (QSAR'S), detailed in the Technical Guidance Document (TGD), can be unreliable for cationic amines and derivatives of these and therefore were not used in the estimation of adsorption coefficient. Although correction factors can be applied, it has been demonstrated through experience that they can significantly under estimate the adsorption coefficient of cationic substances.
Therefore, due to the above, the adsorption coefficient of the test material was estimated using specialist chemical estimation software.
Using fragment constant methodology, the adsorption coefficient of the test material has been estimated to be 2.84 x 10^3, log10Koc 3.45.
GLP compliance:
yes (incl. certificate)
Key result
Type:
log Koc
Value:
3.43 dimensionless
Conclusions:
Using fragment constant methodology, the adsorption coefficient of the test material has been estimated to be 2.84 x 103, log10Koc 3.45.
Executive summary:

Adsorption Coefficient. For the following reasons, no determination of Adsorption Coefficient was possible by Method C19 of Commission Directive 2001/59/EC (which constitutes Annex V of Council Directive 67/548/EEC).

Sewage Treatment plants usually operate between pH 5.5 and 7.5. For this reason, testing is usually carried out within this pH range. However, at this pH, the quaternary amine group present in the test material would be in its ionised form. Experience has shown that positively charged nitrogens can interact with the stationary phase of the column by forces other than partitioning. This was to be the case for this material in method development investigations, The test material could not be eluted from the analytical colurnn.

More importantly, the test material was shown to be significantly surface active in the partition coefficient test. The determination of Adsorption coefficient by HPLC estimation is not suitable for surface active materials.

Quantitive Structure Activity Relationships (QSAR'S), detailed in the Technical Guidance Document (TGD), can be unreliable for cationic amines and derivatives of these and therefore were not used in the estimation of adsorption coefficient. Although correction factors can be applied, it has been demonstrated through experience that they can significantly under estimate the adsorption coefficient of cationic substances.

Therefore, due to the above, the adsorption coefficient of the test material was estimated using specialist chemical estimation software.

Using fragment constant methodology, the adsorption coefficient of the test material has been estimated to be 2.84 x 103, log10Koc 3.45.

Description of key information

Using fragment constant methodology, the adsorption coefficient of the test material has been estimated to be 2.84 x 103, log10Koc 3.45.

Key value for chemical safety assessment

Koc at 20 °C:
2 818

Additional information

[LogKoc: 3.45]