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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: - Study generated according to generally valid and/or internationally accepted testing guidelines - Performed according to GLP - Test parameters based on specific testing guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
Version / remarks:
OECD Guideline No. 121 "Estimation of the adsorptiopn Coeffiecient (Koc) on Soil and Sewage Sludge using High Performance Liquid Chromatography (HPLC)" (2001) Method C19 of Commission Diective 2001/59/EC.
Deviations:
no
Principles of method if other than guideline:
EC Directive 2001/59/EC, C. 19, EC publication L 225, August 2001.
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No
Radiolabelling:
not specified
Test temperature:
25°C
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: Varian autosampler 9095
Varian Pump 9012
Varian UV/VIS detector ProStar 310
Jones column oven 7990
- Detection system: Test item: 220 nm
Reference items: 210 nm
Sodium nitrate: 210 nm

MOBILE PHASES
- Type: Water/acetonitrile (45:55; v/v)
- pH: pH 6.4

REFERENCE SUBSTANCES
- Identity:


- Column: LiChrospher 100 CN, particle size 5 pm, 250 mm x 4 mm
- Injection volume: 50 µl
- Flow: 1.0 mI/mm
- Run time: 20 minutes
- Retention times: See Table 1 below


Analytical monitoring:
yes
Details on sampling:
HPLC Method used
Details on matrix:
See Report
Details on test conditions:
See Report
Computational methods:
See Report
Type:
log Koc
Value:
> 5.63
Temp.:
25 °C
Remarks on result:
other: this is equal to a Koc value of > 426580 using the HPLC method.
Details on results (HPLC method):
Test System: This method utilises a high performance liquid chromatograph with UV/VIS detector, reversed phase column and an aqueous mobile phase. Details are given below.

Performance of the Test:
Test Item Solution:
FP-100 (37.92 mg) was dissolved in acetonitrile (100 ml) to prepare a stock solution of 379.2 µg/mI. The stock solution1 (1 ml) was diluted with a solvent mixture of water and acetonitrile (45:55; v/v) to 10 ml to obtain a standard solution of 37.92 µg/mI. The pH value of the test item solution was determined to be 6.9. This test item solution was injected three times.

Reference Solutions:
The reference items were chosen from the list given in the OECD Guideline No. 121 and EC Directive C.19.

Stock solutions of the reference items were prepared as described:
10.74mg of isoproturon, 12.90mg of linuron, 9.90mg of 2,4-DDT, 11.27mg of pyrazophos, 13.34mg of diclofop-methyl and 10.32 mg of acetanilicle were each dissolved in 10 ml of acetonitrile.

A combined reference solution was prepared by transferring 65 µl of the acetanilide stock solution, 45 µl of the isoproturon stock solution, 30 µl of the linuron stock solution, 200 µl of the pyrazophos stock solution, 40 µl of the diclofop-methyl stock solution and 85 µl of the 2,4-DDT stock solution into one volumetric flask and diluting to a volume of 10 ml with a solvent mixture of water and acetonitrile (45:55; v/v). This reference solution was injected six times.

Sodium nitrate (11.94 mg) was dissolved in 20 ml of acetonitrile to obtain a stock solution. The stock solution (20 µl) was diluted to I ml with a solvent mixture of water and acetonitrile (45:55; v/v), This sodium nitrate solution was injected twice for the determination of the dead time of the HPLC system.
- Retention times of reference substances used for calibration:
- Details of fitted regression line (log k' vs. log Koc): see below


- Graph of regression line attached: see below


- Average retention data for test substance: see below

Adsorption and desorption constants:
Log Koc >5.63
Recovery of test material:
N/A
Concentration of test substance at end of adsorption equilibration period:
See Report
Concentration of test substance at end of desorption equilibration period:
See Reprot
Transformation products:
not specified
Statistics:
See Report

- Retention times of reference substances used for calibration:

- Details of fitted regression line (log k' vs. log Koc): see below

 

- Graph of regression line attached: see below

 

- Average retention data for test substance: see below

Validity criteria fulfilled:
yes
Conclusions:
In conclusion, the log of the adsorption coefficient (Koc) of FP-100 was estimated to be log Koc > 5.63 which is equal to a Koc value of > 426580 using the HPLC method. This value indicates that FP-100 is immobile and remains preferably in soil.
Executive summary:

Not provided in the report

Description of key information

In conclusion, the log of the adsorption coefficient (Koc) of FP-100 was estimated to be log Koc > 5.63 which is equal to a Koc value of > 426580 using the HPLC method. This value indicates that FP-100 is immobile and remains preferably in soil.

Key value for chemical safety assessment

Koc at 20 °C:
426 580

Additional information

The test item solution was injected three times and the combined reference solution was injected six times. The log Koc of the test item was calculated using a regression curve (log k vs. log Koc) and was found to be 7.4 (main peak) and 9.2 (second peak), which is equal to a K value of 26588297 (main peak) and 1450231106 (second peak). The retention times of both test item peaks were higher than the retention time of the highest reference item used (2,4-DDT) with log Koc 5.63, which is equal to a Koc 426580. In the present study the reference items covered the range of log Koc 1.25 to log Koc 5.63.

 

The chromatography of the test item resulted in two peaks. The retention times of the peaks were reproducible. The HPLC method was therefore considered to be suitable for the purpose of the study.

The capacity factor (k’) was calculated for each reference item using the retention times. The tabulated values represent rounded mean results, which were obtained by calculation using the exact raw data.

 

In conclusion, the log of the adsorption coefficient (Koc) of FP-100 was estimated to be log Koc > 5.63 which is equal to a Koc value of > 426580 using the HPLC method. This value indicates that FP-100 is immobile and remains preferably in soil.