Registration Dossier
Registration Dossier
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EC number: 635-476-4 | CAS number: 88349-88-6
Adsorption / desorption
Administrative data
Link to relevant study record(s)
Description of key information
Two OECD 106 batch equilibrium studies are available for cloquintocet acid. In the first study (Crabtree & Boardman, 2014) the the adsorption and desorption characteristics of [14C]-cloquintocet acid were determined in seven soils using a standard batch equilibrium method, in the dark at 20°C. Concentrations of test substance in the aqueous phase were initially 5, 2, 0.5, 0.2 and 0.05 μg/mL. The adsorption phase was 48 hours and was followed by a single desorption phase. Freundlich adsorption coefficients (KFOC) were in the range 872 to 2562 L/kg for all soils except one (Yolo) which had a KFOC of 6568 L/kg.
A second study (Hill, 1994) investigated the Freundlich adsorption/desorption isotherms of cloquintocet acid in three soils. Four dilutions of cloquintocet acid were prepared in 0.01 M CaCl2 and single aliquots of the respective stock solutions (5 mL) were added to obtain concentrations of 50, 25, 10 and 5 ppm. The equilibrium time for this study was seven hours. Relating the Freundlich adsorption constant (K') to the organic carbon content of the three soils gave respective organic carbon adsorption coefficients (K'oc) of 1261, 1186, and 2870 µg/g (mean value: 1772 µg/g).
The values from Crabtree & Boardman (2014) were considered the key values here, as this study is more recent, is considered to be of a higher quality and has a greater number of soils. From this data, an arithmetic mean value of 2324 L/kg was calculated.
Key value for chemical safety assessment
- Koc at 20 °C:
- 2 324
Additional information
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