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Environmental fate & pathways

Adsorption / desorption

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Description of key information

log Koc of 3.2 at 20 °C

Key value for chemical safety assessment

Koc at 20 °C:
1 585

Additional information

The adsorption/desorption behavior of 14C-labelled test substance was investigated on five different US soils and one European soil (BASF, 2015). The study was carried out according to the OECD Guideline No.106. The six soils covered a range of pH from 5.5 to 7.8, a range of organic carbon content from 0.81% to 1.22% and four different USDA textural classes: Silt Loam, Loam, Loamy Sand and Sandy Loam. For the determination of the adsorption isotherm, five different concentrations (nominal 2.00, 1.00, 0.20, 0.10 and 0.02 µg/mL) in 0.01 mol/L CaCl2 solutions of test item were used. The ratio of soil versus test solution was 1/10. The tests were performed at a temperature of 20 ± 2 °C and at the adsorption equilibrium time of 48 hours for all six soils. The concentrations of the test item in the adsorption/desorption solutions and soils extracts were determined by liquid scintillation counting. The stability of 14C-labelled test substance in the test system was confirmed by Radio-HPLC analysis of the sample solutions at different phases. The following adsorption (all soils) and desorption parameters (Louisiana and Lufa 5M soils only) were measured for the 14C-labelled test substance: distribution coefficients Kd and Koc at five concentration levels, the Freundlich coefficient KF, the Freundlich exponent 1/n, and the corresponding KFoc values. The mass balance of 14C-labelled test substance for the test soils ranged from 99.2 % (Indiana soil) to 107.8 % (North Carolina soil) of the total applied radioactivity (TAR), respectively.

Based on the results a mean Koc value of 1490 L/kg was determined.

[LogKoc: 3.2]