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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
31 Mar - 04 Jun 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Deviations:
yes
Remarks:
test perfomed with 3 soils instead of 5 soils. The partitioning to soil was not based on a Freundlich isotherm but was evaluated based on only one test concentration.
GLP compliance:
yes (incl. certificate)
Type of method:
batch equilibrium method
Media:
soil
Specific details on test material used for the study:
Appearance of the test material as stated in the report: pale yellow liquid
Radiolabelling:
no
Test temperature:
20 - 25 °C
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 1 g/L
- Sampling interval: 24 hours
- Sample storage before analysis: no
Details on matrix:
LUFA standard soil 2.2
Name: LUFA standard soil 2.2
Location:
Groβer Striet no. 585
Hanhofen
Germany
Sampling date: 29-07-2009
Texture: Loamy sand
pH (0.01M CaCl2) 5.5 ± 0.1
Organic carbon (%): 2.09 ± 0.40
Particle size distribution:
%clay (< 2µm): 6.4 ± 0.9
% silt (2 – 50 µm): 11.6 ± 0.7
% sand (50 – 2000 µm): 82.0 ± 0.7
CEC (meq/100g) 10.0 ± 0.5
Water holding capacity (%) 46.5 ± 6.0

LUFA standard soil 6S
Name: LUFA standard soil 6S
Location:
In der unteren Hohnert no. 2412
Siebeldingen
Germany
Sampling date: 17-08-2009
Texture: Clay
pH (0.01M CaCl2) 7.2 ± 0.1
Organic carbon (%): 1.69 ± 0.17
Particle size distribution:
%clay (< 2µm): 41.7 ± 1.3
% silt (2 – 50 µm): 36.1 ± 2.2
% sand (50 – 2000 µm): 22.2 ± 1.5
CEC (meq/100g) 22.0 ± 6.6
Water holding capacity (%) 39.6 ± 5.0

3Eurosoil no. 4
Name: Eurosoil no.4, certified reference material IRMM 443-4
Location: Data can be obtained from IRMM
Sampling date: Data can be obtained from IRMM
Texture (USDA): Silt
pH (0.01M CaCl2) 6.8 ± 0.6
Organic carbon (%): 1.31
Particle size distribution:
%clay (< 2µm): 20.3
% silt (2 – 50 µm): 75.7
% sand (50 – 2000 µm): 4.1
CEC (meq/100g) 17.3
Water holding capacity (%) Data can be obtained from IRMM
Details on test conditions:
TEST CONDITIONS
- Buffer: 0.01M CaCl2
- pH: 7 - 8

TEST SYSTEM
- Type, size and further details on reaction vessel: Glass centrifuge tube of 40 mL volume closed with teflon cap
- Water filtered (i.e. yes/no; type of size of filter used, if any): no
- Amount of soil/sediment/sludge and water per treatment (if simulation test): 0.4 g of soil and 40 mL of liquid
- Soil/sediment/sludge-water ratio (if simulation test): 1 : 100
- Number of reaction vessels/concentration: 2
- Measuring equipment: pH meter
- Test performed in closed vessels due to significant volatility of test substance: yes
- Test performed in open system: no
- Method of preparation of test solution: stock colution of test substance made in 0.01 M CaCl2
- Are the residues from the adsorption phase used for desorption: yes
- Other:
Sample No.:
#1
Duration:
24 h
Initial conc. measured:
1 000 mg/kg soil d.w.
Temp.:
22 °C
Sample no.:
#1
Duration:
48 h
Temp.:
22 °C
Type:
log Koc
Value:
3.2 dimensionless
Temp.:
22 °C
% Org. carbon:
2.09
Remarks on result:
other: LUFA 2.2
Type:
log Koc
Value:
3.7 dimensionless
Temp.:
22 °C
% Org. carbon:
1.69
Remarks on result:
other: LUFA 6S
Type:
log Koc
Value:
3.6 dimensionless
Temp.:
22 °C
% Org. carbon:
1.31
Remarks on result:
other: Eurosoil 4
Details on results (HPLC method):
- Retention times of reference substances used for calibration: 24 - 28 min
- Details of fitted regression line (log k' vs. log Koc): r2 = 0.9944
- Graph of regression line attached

Description of key information

The substance has a potential for adsorption to soil and suspended matter based on the log Koc of 3.5 (OECD 106)

Key value for chemical safety assessment

Koc at 20 °C:
3 162.28

Additional information

The adsorption/desorption of the substance was investigated in a study conducted according to OECD guideline 106. The tested number of soils deviated from the guideline recommendation. Instead of five soils, the adsorption/desorption potential was tested using three different soils. The used standard soils were LUFA standard soil 2.2 (loamy sand), LUFA standard soil 6S (clay) and Eurosoil 4 (silt). An initial test concentration of 100.2 mg/L was applied to all soil types. The adsorption was determined by analysis of substance concentration in the water phase after 24, 48 and 72 hours. The determined Kd values were 3.2, 8.5 and 5.6 cm³/g for LUFA standard soil 2.2 (loamy sand), LUFA standard soil 6S (clay) and Eurosoil 4, respectively. The log Koc values were 3.2, 3.7 and 3.6 for LUFA standard soil 2.2 (loamy sand), LUFA standard soil 6S (clay) and Eurosoil 4, respectively. The geometric mean log Koc for all three soil types is 3.5.