1-(3-chloropyridin-2-yl)-N-[4-cyano-2-methyl-6-(methylcarbamoyl)phenyl]-3-{[5-(trifluoromethyl)-2H-tetrazol-2-yl]methyl}-1H-pyrazole-5-carboxamide

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

3 February 2011 - 1 April 2011

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)

Qualifier:

according to guideline

Guideline:

other: US EPA Fate, Transport and Transformation Test Guidelines, OPPTS 835.1230, Adsorption/Desorption (Batch Equilibrium) 2008

Qualifier:

according to guideline

Guideline:

other: Canada PMRA, Guidelines for Registration of Pesticides, Environmental Chemistry and Fate, 1987

GLP compliance:

yes

Remarks:

Ministerium für Arbeit, Gesundheit und Soziales des Landes Nordrhein-Westfalen, Düsseldorf, Germany

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

yes

Test temperature:

20 °C

Analytical monitoring:

yes

Details on sampling:

After each adsorption and desorption step the aqueous supernatant was separated from the soil by centrifugation and the amount of test substance in the supernatants was analyzed by liquid scintillation counting (LSC).
In the preliminary parental mass balance test, the soil was additionally extracted three times using acetonitrile. The aqueous supernatant and the combined soil extracts were analyzed by LSC and HPLC/radiodetection to determine the stability of the test item and to establish the parental mass balance. The limit of detection (LOD) and limit of quantitation (LOQ) for HPLC/radiodetection analysis were 0.3 and 0.9%AR, respectively.
The partition of the test item in the adsorption and desorption batch equilibrium experiment was determined based on the radioactivity content in the supernatant only due to the stability of the test item demonstrated by the parental mass balance. After the desorption step, the soil was air-dried and the radioactivity content determined by combustion/LSC to establish the material balance.
- Concentrations: 0.5, 0.15, 0.05, 0.015 and 0.005 mg/L in aqueous 0.01 M CaCl2
- Sampling interval: The equilibration time was 24 hours for adsorption and each desorption step.
- Sample storage before analysis: Samples were analyzed immediately after preparation or sampling.

Matrix no.:

#1

Matrix type:

loamy sand

% Clay:

5

% Silt:

16

% Sand:

79

% Org. carbon:

1.8

pH:

6.2

CEC:

8.4 meq/100 g soil d.w.

Bulk density (g/cm³):

1.21

Matrix no.:

#2

Matrix type:

silt loam

% Clay:

19

% Silt:

56

% Sand:

25

% Org. carbon:

2.7

pH:

6.4

CEC:

12.7 meq/100 g soil d.w.

Bulk density (g/cm³):

1.05

Matrix no.:

#3

Matrix type:

silt loam

% Clay:

15

% Silt:

54

% Sand:

31

% Org. carbon:

2.7

pH:

5.3

CEC:

9.6 meq/100 g soil d.w.

Bulk density (g/cm³):

1.04

Matrix no.:

#4

Matrix type:

loam

% Clay:

25

% Silt:

40

% Sand:

35

% Org. carbon:

5.1

pH:

7.3

CEC:

19.3 meq/100 g soil d.w.

Bulk density (g/cm³):

0.96

Details on matrix:

COLLECTION AND STORAGE
The soils were sampled from the field (upper horizon of 0 to 20 cm), sieved to a particle size of ≤ 2 mm and stored at ambient temperature for approx. 3 months before study start. The soils were air-dried before application. The soils were taken from agricultural areas representing different geographical origins and different soil properties as required by the guidelines.
- Geographic location: Soils 1, 2, 3, 4 Monheim am Rhein, Burscheid, Burscheid and Blankenheim, Germany, respectively
- Collection procedures: with spade and placed in plastic bags
- Sampling depth (cm): 0 - 20 cm
- Storage conditions: sieved to a particle size of ≤ 2 mm and stored at ambient temperature
- Storage length: approx. 3 months before study start
- Soil preparation (e.g.: 2 mm sieved; air dried etc.): 2 mm sieved and air-dried

PROPERTIES
- Soil texture #1: Loamy sand; #2 Silt loam; #3 Silt loam; #4 Loam
- % sand: #1: 79; #2 25; #3 31; #4 35
- % silt: #1: 16; #2 56; #3 54; #4 40
- % clay: #1: 5; #2 19; #3 15; #4 25
- Soil taxonomic classification: #1: Sandy, mixed mesic, Typic Cambudolls; #2 Loamy, mixed mesic, Typic Argudalfs; #3 Not applicable; #4 Not applicable
- Soil classification system: USDA
- Soil series: Not applicable
- pH: (0.01 M CaCl2 1/2): #1: 6.2; #2 6.4; #3 5.3; #4 7.3
- Organic carbon (%): #1: 1.8; #2 2.7; #3 2.7; #4 5.1
- CEC (meq/100 g): #1: 8.4; #2 12.7; #3 9.6; #4 19.3
- Moisture at 1/3 atm (%): #1: 11.1; #2 23.1; #3 25.6; #4 33.9
- Bulk density (g/cm3): #1: 1.21; #2 1.05; #3 1.04; #4 0.96

Details on test conditions:

TEST CONDITIONS
- Buffer: 0.01 M CaCl2
- pH: 5.7
- Suspended solids concentration: a soil-to-solution ratio of 1/4 (5 g soil (dry weight equivalents)/20 mL solution) for soils Laacher Hof AXXa, Hoefchen Am Hohenseh 4a and Hanscheiderhof and 1/10 (2 g soil (dry weight equivalents)/20 mL solution) for soil Dollendorf II, respectively.
- other: The adsorption and desorption steps were carried out each for 24 hours in the dark at 20 ± 1 °C under continuous agitation.

TEST SYSTEM
- Type, size and further details on reaction vessel: Teflon® centrifuge tubes (volume 42 mL) closed with screw caps. The experiments were performed in duplicate.
- Water filtered (i.e. yes/no; type of size of filter used, if any): No
- Number of reaction vessels/concentration: duplicates
- Test performed in closed vessels due to significant volatility of test substance: Test vessels closed via screw cap. Test substances and/or metabolites are not volatile.
- Test performed in open system:
- Are the residues from the adsorption phase used for desorption: The desorption phase was performed by supplying pre-adsorbed soil samples with fresh aqueous 0.01 M CaCl2 solution for all test concentrations.

Sample No.:

#1

Duration:

24 h

Initial conc. measured:

>= 0.005 - <= 0.5 other: mg/L

pH:

6.2

Temp.:

ca. 20 °C

Remarks:

Loamy sand

Sample No.:

#2

Duration:

24 h

Initial conc. measured:

>= 0.005 - <= 0.5 other: mg/L

pH:

6.4

Temp.:

ca. 20 °C

Remarks:

Silt loam

Sample No.:

#3

Duration:

24 h

Initial conc. measured:

>= 0.005 - <= 0.5 other: mg/L

pH:

5.3

Temp.:

ca. 20 °C

Remarks:

Silt loam

Sample No.:

#4

Duration:

24 h

Initial conc. measured:

>= 0.005 - <= 0.5 other: mg/L

pH:

7.3

Temp.:

ca. 20 °C

Remarks:

Loam

Sample no.:

#1

Duration:

24 h

Conc. of adsorbed test mat.:

0.879 mg/kg soil d.w.

pH:

6.2

Temp.:

20 °C

Remarks:

Loamy sand at inital concentration of a.i. of 0.55 mg/L

Sample no.:

#2

Duration:

24 h

Conc. of adsorbed test mat.:

1.182 mg/kg soil d.w.

pH:

6.4

Temp.:

20 °C

Remarks:

Silt loam at inital concentration of a.i. of 0.55 mg/L

Sample no.:

#3

Duration:

24 h

Conc. of adsorbed test mat.:

1.013 mg/kg soil d.w.

pH:

5.3

Temp.:

20 °C

Remarks:

Silt loam at inital concentration of a.i. of 0.55 mg/L

Sample no.:

#4

Duration:

24 h

Conc. of adsorbed test mat.:

2.167 mg/kg soil d.w.

pH:

7.3

Temp.:

20 °C

Remarks:

Loam at inital concentration of a.i. of 0.55 mg/L

Computational methods:

- Adsorption and desorption coefficients (Kd): Calculation of the Freundlich Constantand relatedKoc was performed according to the OECD 106. The [14]C contents measured in the supernatants of the adsoption and desorption step at equilibration time was used to calculate adsorption and desorptoion isotherms as well as the organic carbon related distribution coefficients (Koc). THe calculations were made according to the following equations:
Freundlich isotherm: x/m =Kf*C^1/N
where C: concentration of a.i. in solutiom at equlibrium
x/m: adsorbed amount of a.i./weight unit of adsorbent (soil) at equilibrium (µg/g)
Kf: Freundlich constant
n: dimensionless
After Log-transformation the Freundlich equation can be written as:
Log(x/m)=1/n*Log(C)+Log(Kf)
- Freundlich adsorption and desorption coefficients: The adsorption constants KF(ads) of calculated based on the Freundlich isotherms of the four test soils ranged from 3.798 to 10.222 mL/g (mean: 6.527 mL/g).
- Slope of Freundlich adsorption/desorption isotherms: The Freundlich exponents 1/n were in the range of 0.8970 to 0.9125 (mean: 0.9041), indicating that the concentration of the test item affects its adsorption behavior in the examined concentration range.
- Adsorption coefficient per organic carbon (Koc): The corresponding, calculated KF, OC(ads) values varied between 195.3 and 252.3 mL/g (mean: 214.8 mL/g).

Key result

Sample No.:

#1

Type:

Koc

Remarks:

adsorption

Value:

211 L/kg

pH:

6.2

Temp.:

20 °C

Matrix:

Laacher Hof AXXa Loamy sand

% Org. carbon:

1.8

Key result

Sample No.:

#2

Type:

Koc

Remarks:

adsorption

Value:

252.3 L/kg

pH:

6.4

Temp.:

20 °C

Matrix:

Hoefchen Am Hohenseh 4a Silt loam

% Org. carbon:

2.7

Key result

Sample No.:

#3

Type:

Koc

Remarks:

adsorption

Value:

195.3 L/kg

pH:

5.3

Temp.:

20 °C

Matrix:

Hanscheiderhof Silt loam

% Org. carbon:

2.7

Key result

Sample No.:

#4

Type:

Koc

Remarks:

adsorption

Value:

200.4 L/kg

pH:

7.3

Temp.:

20 °C

Matrix:

Dollendorf II Loam

% Org. carbon:

5.1

Adsorption and desorption constants:

The adsorption constants KF(ads) of the test substance calculated based on the Freundlich isotherms of the four test soils ranged from 3.798 to 10.222 mL/g (mean: 6.527 mL/g) and the normalized adsorption constants KF, OC(ads) (normalized to organic carbon content) ranged from 195.3 to 252.3 mL/g (mean: 214.8 mL/g). The Freundlich exponents 1/n were in the range of 0.8970 to 0.9125 (mean: 0.9041), indicating that the concentration of the test item affects its adsorption behavior in the examined concentration range.

Recovery of test material:

At the end of the adsorption phase 53.8 – 65.4%AR was adsorbed to soil Laacher Hof AXXa, 66.6 – 75.5%AR was adsorbed to soil Hoefchen Am Hohenseh 4a, 60.2 – 70.0%AR was adsorbed to soil Hanscheiderhof and 54.7 – 66.1%AR was adsorbed to soil Dollendorf II.

Sample no.:

#1

Duration:

24 h

% Adsorption:

>= 53.8 - <= 65.4

Sample no.:

#2

Duration:

24 h

% Adsorption:

>= 66.6 - <= 75.5

Sample no.:

#3

Duration:

24 h

% Adsorption:

>= 60.2 - <= 70

Sample no.:

#4

Duration:

24 h

% Adsorption:

>= 54.7 - <= 66.1

Sample no.:

#1

Duration:

24 h

% Desorption:

>= 20 - <= 26.6

Sample no.:

#2

Duration:

24 h

% Desorption:

>= 14.7 - <= 19.2

Sample no.:

#3

Duration:

24 h

% Desorption:

>= 18.9 - <= 23.3

Sample no.:

#4

Duration:

24 h

% Desorption:

>= 21.1 - <= 27.8

Transformation products:

not measured

Details on results (Batch equilibrium method):

PRELIMINARY TEST
- Weighed soil: 5 or 2 g dwt
- Volume of CaCl2 solution: 20 mL
- Test substance concentration in final solution: 0.5 mg/L

MAIN TEST: PERFORMANCE
- Test material stability during adsorption/desorption phase: The overall material balance for all concentrations was in the range of 90.2 to 98.8% (mean: 95.0%) of the applied radioactivity.
- Experimental conditions maintained throughout the study: Yes
- Buffer/test substance interactions affecting sorption: No
- Further chemical interactions: No
- Buffer-catalyzed degradation of test substance: No

Statistics:

Arithmetic means were used for all LSC measurements, standard deviation was calculated for the values as follows:
Square Root of (Sum((x - x(hat)^2)/n

Percentage of adsorbed and desorbed Test Substancen soils(mean values)

	Test Concentration [mg/L]
	Adsorption^1					Desorption^2
Soil	0.55	0.165	0.05	0.016	0.005	0.55	0.165	0.05	0.016	0.005
Laacher Hof AXXa	54.0	53.8	57.4	61.4	65.4	25.9	26.6	24.5	22.9	20.0
Hoefchen Am Hohenseh 4a	66.6	68.5	72.3	73.9	75.5	19.2	18.8	16.7	15.2	14.7
Hanscheiderhof	60.2	62.3	66.1	67.0	70.0	23.3	21.6	20.3	19.2	18.9
Dollendorf II	54.7	56.2	60.5	63.2	66.1	27.8	26.9	25.0	23.8	21.1
^1 end of adsorption phase, mean values expressed as percentage of applied radioactivity
^2 end of first desorption phase, mean values expressed as percentage of the initially adsorbed amount Adsorption/desorption constants and correlation coefficients of Test Substance in soil at 20 °C     Adsorption Desorption Soil pH^1 OC KF 1/n R² KF, OC KF 1/n R² KF, OC     [%] [mL/g]     [mL/g] [mL/g]     [mL/g] Laacher Hof AXXa 6.2 1.8 3.798 0.8970 0.9985 211.0 8.829 0.9256 0.9983 490.5 Hoefchen Am Hohenseh 4a 6.4 2.7 6.813 0.9083 0.9998 252.3 13.537 0.9256 0.9990 501.4 Hanscheiderhof 5.3 2.7 5.274 0.9125 0.9995 195.3 11.560 0.9422 0.9997 428.2 Dollendorf II 7.3 5.1 10.222 0.8985 0.9994 200.4 20.869 0.9235 0.9992 409.2 Mean 6.527 0.9041 0.9993 214.8 13.699 0.9292 0.9990 457.3   ^1 pH in 0.01 M CaCl2

Description of key information

Mean measured Koc (OECD 106) = 214.75 (log Koc = 2.33) , M-427580-01-1

Key value for chemical safety assessment

Koc at 20 °C:

214.75

Additional information

The adsorption/desorption behavior was studied in four soils in the dark in the laboratory at 20 ± 1 °C using the batch equilibrium method according to OECD guidance 106 (M-427580-01-1). The test substance was applied at nominal concentrations of 0.5, 0.15, 0.05, 0.015 and 0.005 mg/L in aqueous 0.01 M CaCl2 solution. The overall mass balances were determined by LSC of the adsorption and desorption supernatants, soil extracts and combustion of the remaining soils. The recovery of the applied radioactivity for all concentrations and soils was in the range of 90.2 to 98.8% (mean: 95.0%). The complete material balances found for all soils and concentrations demonstrated that there was no significant loss of radioactivity dissipated from the test systems or during sample processing.

The calculated adsorption constants KF(ads) of the Freundlich isotherms for the four test soils ranged from 3.798 mL/g to 10.222 mL/g (mean: 6.527 mL/g). The Freundlich exponents 1/n were in the range of 0.8970 to 0.9125 (mean: 0.9041), indicating that the concentration of the test item affected the adsorption behavior in the examined concentration range. The corresponding, calculated KF, OC(ads) values varied between 195.3 and 252.3 mL/g (mean: 214.8 mL/g).

The desorption KF(des) and the normalized Koc(des) values were significantly higher (about two times higher) than those obtained for the adsorption phase, indicating that the test item once adsorbed to soil is not readily desorbed.

[LogKoc: 2.33]