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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The Log Koc for the substance is calculated to be 326 L/kg by weight averaged of constituents value.

Key value for chemical safety assessment

Koc at 20 °C:
160

Additional information

No determination of the adsorption coefficient was possible by the HPLC estimation method because this method is not considered valid for strong acid.

The adsorption coefficient Koc of the two main constituents (97%) of the registered mixture, the monoester and the diester, was calculated with three different QSAR's models:

- An equation based on the correlation between the partition coefficient Kow and the adsorption coefficient Koc.

- Two equations developed in the model KOCWIN (version 2.00, September 2010) based on two separate methodologies. The first is the use of a first-order molecular connectivity index (MCI) to which group contribution factors (correction factors) are added to maximize estimation accuracy. The second method replaces the MCI descriptor with log10Kow.

 -Values of partition coefficient for the unionized, environmentally relevant, forms of the constituents of the registered mixture were obtained from the specialized predictive software KOWWIN, version 1.68, September 2010, © US EPA. 

All models were considered appropriate and valid options for assessing the adsorption coefficient of the monoester and the diester constituents of the registered mixture.  The results generated in each case are summarized in the following table.

Since the different models gave the similar results of Log Koc for both the monoester and the diester, the geometric mean was calculated as Koc for the monester and the diester components.

Methodology

Estimated Value of Adsorption Coefficient as log10Koc

Monoester Component

Diester Component

QSAR

1.78

2.77

KOCWIN (MCI)

1.48

2.82

KOCWIN (from log10Kow)

1.72

2.84

Geometric mean as log10Koc

1.66

2.81

Geometric mean as Koc

45.7

646

Based on the weighted average with the composition rates of its two main components (50.9% and 45.8% w/w for the monoester and the diester, respectively) an adsorption/desorption coefficient of 2.2 (0.87 +1.33) at 20°C was assessed for the registered mixture for chemical risk assessment purpose.

[LogKoc: 2.2]