3-anilino-5-methyl-5-(4-phenoxyphenyl)-1,3-oxazolidine-2,4-dione;famoxadone (ISO)

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: 163-1: Leaching and Adsorption-Desorption Studies

Deviations:

no

GLP compliance:

yes

Type of method:

batch equilibrium method

Media:

soil

Specific details on test material used for the study:

Substance ID: [14C]DPX-JE874
Lot #: 3507-061
Radiochemical purity: 96.0%
Specific activity: 65.44 μCi/mg

Radiolabelling:

yes

Test temperature:

25°C

Analytical monitoring:

yes

Details on sampling:

- Sampling interval: The test vessels were mixed on a shaker (low speed) in an environmental chamber maintained at 25°C, and an individual test vessel for each soil was collected at approximately 2, 4, 6, and 24 hours.
- Sample storage before analysis: The reference standards, test substance stock solution, and the test dosing solutions were all stored at <-20°C. The aqueous and soil phase samples were all stored frozen (<-20°C) after collection.

Matrix no.:

#1

Matrix type:

silty clay loam

% Clay:

28

% Silt:

56

% Sand:

16

% Org. carbon:

3.72

pH:

6.7

CEC:

35.8 other: meq/100 g

Bulk density (g/cm³):

1.2

Details on matrix:

COLLECTION AND STORAGE
- Geographic location: Rochelle, Illinois

PROPERTIES
- % sand: 16
- % silt: 56
- % clay: 28
- Soil taxonomic classification: Silty Clay Loam
- Soil classification system: USDA
- pH: 6.7
- Organic carbon (%): 3.72
- CEC (meq/100 g): 35.8
- Moisture at 1/3 atm (%): 32.9
- Bulk density (g/cm3): 1.2

Details on test conditions:

TEST SYSTEM
- Type, size and further details on reaction vessel: Glass centrifuge tubes, equipped with Teflon-lined screw caps
- Number of reaction vessels/concentration: Experiments were performed in duplicate
- Method of preparation of test solution: A test solution was prepared by transferring required amount of the original radiolabeled stock solution to volumetric flasks. The acetone was evaporated under a gentle stream of nitrogen and the flasks were brought to volume with 0.01 M CaCl2.

Sample No.:

#1

Duration:

24 h

Temp.:

25 - 25.4 °C

Remarks:

The nominal dose solution concentrations were 25, 10, 5.0, and 2.5 ng/mL.

Sample no.:

#1

Duration:

24 h

Temp.:

25 °C

Remarks:

Two desorption cycles were performed on the highest concentration of the test substance

Computational methods:

- Adsorption and desorption coefficients (Kd): Cs adj (soil phase concentration adjusted for degradation of the test substance (*0.713))/Cw adj (aqueous phase concentration adjusted for degradation of the test substance (*0.713))
- Other: Equilibration time was determined from plots of the percent adsorption (A) against time.

Key result

Sample No.:

#1

Type:

Kd

Value:

123 other: mL/g

pH:

6.7

Temp.:

25 °C

Matrix:

Soil

% Org. carbon:

3.72

Sample No.:

#1

Type:

other: Kom

Value:

1 923 other: mL/g

pH:

6.7

Temp.:

25 °C

Matrix:

Soil

% Org. carbon:

3.72

Sample No.:

#1

Type:

Koc

Value:

3 307 other: mL/g

pH:

6.7

Temp.:

25 °C

Matrix:

Soil

% Org. carbon:

3.72

Sample No.:

#1

Type:

other: Kf

Value:

127 dimensionless

pH:

6.7

Temp.:

25 °C

Matrix:

Soil

% Org. carbon:

3.72

Sample No.:

#1

Type:

other: Kfom

Value:

1 977 dimensionless

pH:

6.7

Temp.:

25 °C

Matrix:

Soil

% Org. carbon:

3.72

Sample No.:

#1

Type:

other: Kfoc

Value:

3 401 dimensionless

pH:

6.7

Temp.:

25 °C

Matrix:

Soil

% Org. carbon:

3.72

Sample No.:

#1

Type:

other: 1/n

Value:

1.02 dimensionless

pH:

6.7

Temp.:

25 °C

Matrix:

Soil

% Org. carbon:

3.72

Adsorption and desorption constants:

Percent of test substance desorbed after first desorption interval (D1): 3.49
Percent of test substance desorbed after first desorption interval (D2): 2.77
Total percent of test substance desorbed after both desorption intervals (DT): 6.26

Recovery of test material:

LSC analysis of dose solutions at a nominal concentration of 2.5 and 25 ng/mL prepared in 0.01 M CaCl2 in a glass centrifuge tube after 24 hours resulted in recoveries of 107.1 and 108.0%, respectively. This shows that no significant test substance was lost from the solutions and the test substance did not adsorb to the glass test vessel.

Sample no.:

#1

Duration:

24 h

% Desorption:

97.3

Remarks on result:

other: average material balance

Transformation products:

yes

Remarks:

IN-JS940, IN-JL856, and IN-H3310

Details on results (Batch equilibrium method):

PRELIMINARY TEST
- Sample purity: 96.0%
- Weighed soil: In order to determine the test substance equilibration time, five test vessels were prepared containing 5 grams (dry weight equivalent) of test soil and 25 mL of 0.01 M CaCl2.
- Volume of CaCl2 solution: Approximately 250-mL
- Initial test substance concentration: 25 ng/mL and 2.5 ng/mL in 0.01 M CaCl2
- Other: At all timepoints, the percent adsorption of the test substance at the 1:5 soil-to-solution ratio was >96%. Mass balance of the test substance at equilibrium was 95.4% of the applied radioactivity.

MAIN TEST: PERFORMANCE
- Test material stability during adsorption/desorption phase: amount of test substance in the soil extract for the 5 and 25 ng/mL concentration levels were 82.4% and 60.1%, respectively. The average percent test substance remaining in the soil as parent was 71.3%. Although the test substance was found to be stable during the equilibration experiments, a longer shaking time of 24 hours resulted in some degradation. The extraction efficiency of the extraction method also decreased from approximately 97% for the 2-hour equilibration sample to 82 and 62% for the 5 and 25 ng/mL level soil extract samples, respectively. This suggests that over time the test substance becomes irreversibly bound, or that the test substance degrades on the soil and its metabolites could not be extracted with the solvent system used.
- Experimental conditions maintained throughout the study: Yes

TRANSFORMATION PRODUCTS
- The three metabolite peaks observed in the soil extract sample were identified as IN-JS940, IN-JL856, and IN-H3310, respectively. The identities were confirmed by HPLC co-injection of the mixed cold standard with the soil extract sample. The percent recovered of each metabolite was approximately 10, 25, and 5% (as determined from the 25 ng/mL sample data) for IN-JS940, IN-JL856, and IN-H3310, respectively.

Validity criteria fulfilled:

yes

Conclusions:

The strong adsorption and weak desorption behavior of the test substance are indicative of compounds with low soil mobility potential.

Executive summary:

The adsorption and desorption properties of the test substance were investigated to assess its potential mobility in soils. The adsorption coefficients Kd, Kom, and Koc and the Freundlich adsorption isotherm parameters KF, KFom, KFoc, and 1/n were calculated on one North American soil.

The adsorption/desorption of the test substance was examined on one soil: a silty clay loam soil from Rochelle, Illinois (designated as Drummer #7). The percent organic matter (Walkley-Black method) of the soil was 6.4%, and the pH in water was 6.7.

One adsorption experiment was performed using the batch equilibration method in soil with four concentrations of the test substance in 0.01 M calcium chloride (CaCl2). Two desorption cycles were performed on the highest concentration of the test substance. The sorption coefficients Kd, Kom, and Koc were calculated at each concentration of the test substance. These coefficients were corrected for degradation of the parent material detected by HPLC analysis of definitive soil extracts. The average adsorption coefficient, Kd, corrected for degradation of the test substance, was 123. The average organic matter normalized adsorption coefficient Kom was calculated to be 1923, while the average organic carbon normalized coefficient Koc value was 3307.

Although >10% adsorption was seen, the values for the Freundlich adsorption isotherm parameter KF, KFom, KFoc, and 1/n were derived from the linear form of the Freundich equation. The value for the Freundlich adsorption isotherm parameter, KF, was 127. The Freundlich adsorption isotherm parameter, KF, was normalized to the organic matter and organic carbon contents for the test soil to calculate the soil sorption coefficients KFom and KFoc. The KFom value was 1977, while the KFoc value was 3401. The value for 1/n was 1.02.

The percent of test substance desorbed from the soil during two desorption intervals (D1 and D2) were calculated and totaled (DT) for the soil at the highest test solution concentration. The test substance was adsorbed extensively by the soil: approximately 95% of the solution concentration was adsorbed. The percent of test substance desorbed from the soil during two desorption intervals (D1 (3.49%) and D2 (2.77%)) were calculated and totaled (DT) for the test soil at the highest test solution concentration. The average DT value was 6.26%.

The strong adsorption and weak desorption behavior of the test substance are indicative of compounds with low soil mobility potential.

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: US EPA 163-1

Deviations:

no

GLP compliance:

yes

Type of method:

batch equilibrium method

Media:

soil

Specific details on test material used for the study:

Substance ID: [14C]DPX-JE874
Lot #: 2675-268
Radiochemical purity: >97%
Specific activity: 59.63 μCi/mg

Radiolabelling:

yes

Test temperature:

25°C

Analytical monitoring:

yes

Details on sampling:

In addition to the zero-time samples (immediately after mixing), samplings were carried out at intervals of 1, 3, 5, and 24 hours. Duplicate, aqueous samples (1-mL each) were removed for direct LSC radioassay.
Measurements of desorption (the monitoring of the amount of radioactivity in the aqueous phase) were carried out daily with ~50-mL aliquots of fresh, untreated 0.01 M CaCl2 solution for four consecutive days.

Matrix no.:

#1

Matrix type:

sandy loam

% Clay:

12.8

% Silt:

26

% Sand:

61.2

% Org. carbon:

1.34

pH:

6.6

CEC:

8.1 other: mEq/100 g

Matrix no.:

#2

Matrix type:

sandy clay loam

% Clay:

21.6

% Silt:

18

% Sand:

60.4

% Org. carbon:

0.58

pH:

8

CEC:

other: mEq/100 g

Matrix no.:

#3

Matrix type:

sand

% Clay:

2.4

% Silt:

8.4

% Sand:

89.2

% Org. carbon:

2.29

pH:

5.9

CEC:

8.2 other: mEq/100 g

Details on matrix:

Soil Preparation
The moisture content for each of the three soils was obtained by weighing triplicate samples of each soil (previously sieved through a 2-mm sieve) into aluminum trays, then vacuum-drying the soil samples in a vacuum oven at ~100°C until constant weight was achieved. For the study, dry-weight equivalents were used with fresh soil from the same lots as those used to determine the moisture content.

Details on test conditions:

TEST SYSTEM
- Type, size and further details on reaction vessel: Screw-cap amber bottles equipped with Poly-Seal™ inserts were used as test containers.
- Water filtered (i.e. yes/no; type of size of filter used, if any):
- Adsorption was determined by mixing a solution of [14C]test substance with soil at a 5:1 volume/weight ratio. A 50-mL aliquot of the [14C]test substance test solution was added to approximately 10-g oven-dried equivalent weight of test soil.
Desorption experiments were carried out with the same soil samples from the 25-ppb test concentration after the termination of the adsorption phase. Similar experimental procedures were used. Soil samples, after the removal of the aqueous phase, were re-equilibrated with ~50 mL of fresh, untreated 0.01 M CaCl2 solution to bring the samples to their original weights.
- Number of reaction vessels/concentration: Each soil and test concentration were duplicated.
- Method of preparation of test solution: Test solutions at 4 different concentrations for each soil were prepared in duplicate. For the 2.5-ng/mL (ppb) concentration, an 81-μL aliquot of the 10-mg/L (ppm) stock solution was diluted with 325 mL of 0.01 M CaCl2 solution. For the 5.0-ppb concentration, a 163-μL aliquot of the 10-ppm stock solution was diluted with 325 mL of 0.01 M CaCl2 solution. For the 10.0-ppb concentration, a 325-μL aliquot of the 10-ppm stock solution was diluted with 325 mL of 0.01 M CaCl2 solution. For the 25-ppb concentration, a 2.5-mL aliquot of the 10-ppm stock solution was diluted to 1 liter of 0.01 M CaCl2 solution.

Sample No.:

#1

Duration:

24 h

Temp.:

25 °C

Remarks:

The nominal dose solution concentrations were 5.0, 10 and 25 ng/mL.

Sample No.:

#2

Duration:

24 h

Temp.:

25 °C

Remarks:

The nominal dose solution concentrations were 5.0, 10 and 25 ng/mL.

Sample No.:

#3

Duration:

24 h

Temp.:

25 °C

Remarks:

The nominal dose solution concentrations were 5.0, 10 and 25 ng/mL.

Sample no.:

#1

Duration:

24 h

Conc. of adsorbed test mat.:

25 other: ppb (ng/mL)

Temp.:

25 °C

Sample no.:

#2

Duration:

24 h

Conc. of adsorbed test mat.:

25 other: ppb (ng/mL)

Temp.:

25 °C

Sample no.:

#3

Duration:

24 h

Conc. of adsorbed test mat.:

25 other: ppb (ng/mL)

Temp.:

25 °C

Computational methods:

Kd = μg adsorbed/g of soil / μg/mL of solution
Koc =Kd / % organic carbon x 100%
The Freundlich adsorption coefficient Kf was obtained by plotting log x/M versus log Ce to yield a linear curve of slope 1/n.

Sample No.:

#1

Type:

Kd

Value:

44.2 dimensionless

Temp.:

25 °C

Matrix:

Speyer Loam soil

% Org. carbon:

1.34

Sample No.:

#2

Type:

Kd

Value:

23.4 dimensionless

Temp.:

25 °C

Matrix:

Donna Clay Loam soil

% Org. carbon:

0.58

Sample No.:

#3

Type:

Kd

Value:

89.1 dimensionless

Temp.:

25 °C

Matrix:

Speyer Sand

% Org. carbon:

2.29

Sample No.:

#1

Type:

other: Kf

Value:

7.4 dimensionless

Temp.:

25 °C

Matrix:

Speyer Loam soil

% Org. carbon:

1.34

Sample No.:

#2

Type:

other: Kf

Value:

4.5 dimensionless

Temp.:

25 °C

Matrix:

Donna Clay Loam soil

% Org. carbon:

0.58

Sample No.:

#3

Type:

other: Kf

Value:

25 dimensionless

Temp.:

25 °C

Matrix:

Speyer Sand

% Org. carbon:

2.29

Sample No.:

#1

Type:

Koc

Value:

3 300 dimensionless

Temp.:

25 °C

Matrix:

Speyer Loam soil

% Org. carbon:

1.34

Sample No.:

#2

Type:

Koc

Value:

4 030 dimensionless

Temp.:

25 °C

Matrix:

Donna Clay Loam soil

% Org. carbon:

0.58

Sample No.:

#3

Type:

Koc

Value:

3 890 dimensionless

Temp.:

25 °C

Matrix:

Speyer Sand

% Org. carbon:

2.29

Adsorption and desorption constants:

The test substance was found to be adsorbed extensively by soil matter, ranging from approximately 80 to 95% of the solution concentration. Soil/water distribution coefficients (Kd) and Freundlich adsorption isotherms (Kf) were calculated (Kd ranging from 17 to 98; Kf ranging from 4.5 to 25). The mean Koc value was found to be 3740. There was a direct correlation between adsorption and soil organic matter content.
Desorption of the adsorbed test substance was minimal (<20%).

Recovery of test material:

Approximately 14-21% of the total adsorbed material was recovered after 4 consecutive days

Sample no.:

#1

Duration:

24 h

% Desorption:

>= 15.4 - <= 16.1

Remarks on result:

other: total adsorbed material recovery

Sample no.:

#2

Duration:

24 h

% Desorption:

>= 20.6 - <= 20.8

Remarks on result:

other: total adsorbed material recovery

Sample no.:

#3

Duration:

24 h

% Desorption:

>= 13.9 - <= 14.5

Remarks on result:

other: total adsorbed material recovery

Details on results (Batch equilibrium method):

Adsorption was immediate, and it reached equilibrium within 3 hours. The test substance was found to be adsorbed extensively by soil matter, ranging from approximately 80 to 95% of the solution concentration.
Desorption of the adsorbed test substance was minimal (<20%).

Conclusions:

The strong adsorption and weak desorption behaviors of the test substance are indicative of compounds with low soil mobility potential.

Executive summary:

The adsorption and desorption behaviors of [4-phenoxyphenyl-14C]test substance were studied in three test soils of different soil properties. The soil organic carbon content of the Speyer sandy loam, Donna clay loam, and Speyer sand ranged from 0.58 to 2.3%. Due to low water solubility of the test substance (~50 ppb), soil adsorption studies were conducted at the nominal concentrations of 5, 10, and 25 ppb with a soil/solution ratio of 1/5.

Adsorption was immediate, and it reached equilibrium within 3 hours. The test substance was found to be adsorbed extensively by soil matter, ranging from approximately 80 to 95% of the solution concentration. Soil/water distribution coefficients (Kd) and Freundlich adsorption isotherms (Kf) were calculated (Kd ranging from 17 to 98; Kf ranging from 4.5 to 25). The mean Koc value was found to be 3740. There was a direct correlation between adsorption and soil organic matter content.

Desorption of the adsorbed test substance was minimal (<20%). The strong adsorption and weak desorption behaviors of the test substance are indicative of compounds with low soil mobility potential.

Description of key information

Study Type	Study Details	Value	Guideline	Reliability
Adsorption/desorption screening study	Batch Equilibrium (Adsorption/Desorption) in Silty clay loam soil	Kd: 123 mL/g Koc: 3307 mL/g	OECD 106; US EPA 163-1	1
Adsorption/desorption screening study	Batch Equilibrium (Adsorption/Desorption) in Sandy loam and Sandy clay loam soil	Kd: 17-98 Koc: 3740	OECD 106; US EPA 163-1	1

Key value for chemical safety assessment

Koc at 20 °C:

3 307