4-(2-chlorophenyl)-N-cyclohexyl-N-ethyl-5-oxo-4,5-dihydro-1H-tetrazole-1-carboxamide

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26 Oct - 25 Nov 1999

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)

Version / remarks:

May 12, 1981

Qualifier:

according to guideline

Guideline:

other: EPA: Pesticide Assess. Guidel., Subdivision N, Chemistry: Env. Fate § 163-1, Leaching & Adsorp/Desorp Studies, Oct 18, 1982 & Addend. 6 on Data Reporting, Jan 1988; EPA Pesticide Registration Rejection Rate Analysis – Env. Fate, EPA 738-R-93-010, Sep 1993

GLP compliance:

yes

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

yes

Test temperature:

20 ± 1 °C

Analytical monitoring:

yes

Details on sampling:

See Table 2 under "Any other information on materials and methods incl. tables" below

Matrix no.:

#1

Matrix type:

loamy sand

% Clay:

7.3

% Silt:

12.4

% Sand:

80.3

% Org. carbon:

1.99

pH:

6.2

CEC:

8 meq/100 g soil d.w.

Bulk density (g/cm³):

2.45

Matrix no.:

#2

Matrix type:

silt loam

% Clay:

12

% Silt:

51.1

% Sand:

36.9

% Org. carbon:

0.98

pH:

7.9

CEC:

8 meq/100 g soil d.w.

Bulk density (g/cm³):

2.55

Matrix no.:

#3

Matrix type:

sandy loam

% Clay:

5

% Silt:

22.6

% Sand:

72.4

% Org. carbon:

1.02

pH:

7.2

CEC:

8 meq/100 g soil d.w.

Bulk density (g/cm³):

2.5

Matrix no.:

#4

Matrix type:

silty clay

% Clay:

42.7

% Silt:

42.3

% Sand:

15

% Org. carbon:

1.09

pH:

6.9

Bulk density (g/cm³):

2.08

Details on matrix:

COLLECTION AND STORAGE
- Soil preparation (e.g.: 2 mm sieved; air dried etc.): Before the start of the test the soils were air-dried and screened to a particle size of ≤ 2 µm. The residual moisture was determined by heating aliquots of the soil using an infrared lamp and simultaneous weighing up to constant weights (Satorius Typ 7393). The amount of residual moisture was taken into consideration when weighing the soils. The weighed amount for the test results from the following: BL = BT (1 + F/100); BL = air-dried soil (g); BT = soil dried at 105 °C; F = moisture in %

PROPERTIES
- Soil texture: see "Matrix properties" above
- % sand: see "Matrix properties" above
- % silt: see "Matrix properties" above
- % clay: see "Matrix properties" above
- Soil taxonomic classification: see "Matrix properties" above
- Soil classification system: USDA [Textural analysis based on DIN 19682 is given under "Any other information on materials and methods incl. tables" below]
- pH (CaCl2): #1: 5.4, #2: 6.7, #3: 6.3, #4: 6.8
- Organic carbon (%): #1: 1.99, #2: 0.98, #3: 1.02, #4: 1.09
- Organic matter (%): #1: 3.42, #2: 1.69, #3: 1.75, #4: 1.87
- CEC (meq/100 g): see "Matrix properties" above
- Extractable Cations (Ca, Mg, Na, K, H) (MEQ/100 g):
- Water content referred to weight of air dried soil (%): #1: 1.33, #2: 1.33, #3: 0.87, #4: 3.42
- Bulk density (g/mL): #1: 2.45, #2: 2.55, #3: 2.5, #4: 2.08

Details on test conditions:

TEST CONDITIONS
- pH: pH values of the clear supernatants after establishing the equilibrium of the adsorption test: 5.0 (soil #1 used), 6.3 (soil #2 used), 6.1 (control), 6.1 (soil #3 used), 6.8 (soil #4 used)

TEST SYSTEM
- Type, size and further details on reaction vessel: Centrifuge tubes with screw cap. Material: Preliminary tests: Teflon®, volume 43 mL; Definitive study: Borosilicate glass, centrifuge tubes with Teflon® screw caps, volume 45 mL
- Number of reaction vessels/concentration: 2 parallel batches were run
- Method of preparation of test solution:
Stock solution I: An amount of 2.94 g CaCl2 * 2 H2O were weighed into a 2 L volumetric flask (0.01 M CaCl2 solution) and filled up with distilled water.
Stock solution II: The radioactively labeled test substance was dissolved in acetonitrile (0.5 mg/mL). The purity of the a.i. was determined using HPLC, radioactivity was measured by LSC. The solution was stored in the dark and in cool conditions.
Application solutions: According to the guideline, the maximum concentration of the test substance should not exceed 1/2 the water solubility. Therefore the adsorption/desorption measurements were carried out at concentrations of 0.5, 0.1, 0.02, and 0.004 mg/L in 0.01 M CaCl2 solution. 14C-labeled test item was used exclusively.
Application solution A: An amount of radioactivity corresponding to 0.5 mg [14C]-test item was pipetted from the stock solution II into a 1 L volumetric flask. The solvent was evaporated and the volumetric flask was then filled up to 2/3 with stock solution I, ultrasonicated for 15 minutes and then shaken for about 24 hours. Due to adsorption effects acetonitril was not evaporated in the definitive study resulting in approximately 0.1% acetonitrile in the solution. After filling up to the calibration mark, aliquots were removed for radioactivity determination. An aliquot of 20 mL was removed from the solution and centrifuged for 30 minutes (> 10 000 g). The radioactivity content of the supernatant was again determined in the LSC.
Application solution B, C and D: Amounts of 50 mL (application solution B), 10 mL (application solution C) and 2 mL (application solution D) were pipetted from application solution A into 250 mL volumetric flasks by means of bulb pipettes, filled up to the calibration mark with stock solution I and shaken for 5 minutes. Subsequently, aliquots were removed from the application solutions for radioactivity determination in the LSC. Application solutions A - D were stored in the refrigerator (4-6 °C).
- Light: dark
- Mechanical Shaker: Overhead shaker (29 ± 2 rpm)

Sample No.:

#1

Duration:

24 h

Initial conc. measured:

7.52 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

5

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.525 mg/L

Sample No.:

#1

Duration:

24 h

Initial conc. measured:

1.68 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.3

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.114 mg/L

Sample No.:

#1

Duration:

24 h

Initial conc. measured:

0.36 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.1

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.023 mg/L

Sample No.:

#1

Duration:

24 h

Initial conc. measured:

0.07 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.8

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.004 mg/L

Sample No.:

#2

Duration:

24 h

Initial conc. measured:

5.77 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

5

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.525 mg/L

Sample No.:

#2

Duration:

24 h

Initial conc. measured:

1.38 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.3

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.114 mg/L

Sample No.:

#2

Duration:

24 h

Initial conc. measured:

0.31 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.1

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.023 mg/L

Sample No.:

#2

Duration:

24 h

Initial conc. measured:

0.06 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.8

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.004 mg/L

Sample No.:

#3

Duration:

24 h

Initial conc. measured:

5.5 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

5

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.525 mg/L

Sample No.:

#3

Duration:

24 h

Initial conc. measured:

1.34 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.3

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.114 mg/L

Sample No.:

#3

Duration:

24 h

Initial conc. measured:

0.29 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.1

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.023 mg/L

Sample No.:

#3

Duration:

24 h

Initial conc. measured:

0.05 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.8

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.004 mg/L

Sample No.:

#4

Duration:

24 h

Initial conc. measured:

5.73 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

5

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.525 mg/L

Sample No.:

#4

Duration:

24 h

Initial conc. measured:

1.38 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.3

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.114 mg/L

Sample No.:

#4

Duration:

24 h

Initial conc. measured:

0.28 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.1

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.023 mg/L

Sample No.:

#4

Duration:

24 h

Initial conc. measured:

0.05 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.8

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#1

Duration:

24 h

Conc. of adsorbed test mat.:

5 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

5

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#1

Duration:

24 h

Conc. of adsorbed test mat.:

1.14 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.3

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#1

Duration:

24 h

Conc. of adsorbed test mat.:

0.25 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.1

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#1

Duration:

24 h

Conc. of adsorbed test mat.:

0.05 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.8

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#2

Duration:

24 h

Conc. of adsorbed test mat.:

3.04 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

5

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#2

Duration:

24 h

Conc. of adsorbed test mat.:

0.77 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.3

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#2

Duration:

24 h

Conc. of adsorbed test mat.:

0.18 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.1

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#2

Duration:

24 h

Conc. of adsorbed test mat.:

0.04 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.8

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#3

Duration:

24 h

Conc. of adsorbed test mat.:

2.86 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

5

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#3

Duration:

24 h

Conc. of adsorbed test mat.:

0.75 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.3

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#3

Duration:

24 h

Conc. of adsorbed test mat.:

0.16 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.1

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#3

Duration:

24 h

Conc. of adsorbed test mat.:

0.03 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.8

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#4

Duration:

24 h

Conc. of adsorbed test mat.:

2.87 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

5

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#4

Duration:

24 h

Conc. of adsorbed test mat.:

0.71 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.3

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#4

Duration:

24 h

Conc. of adsorbed test mat.:

0.16 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.1

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#4

Duration:

24 h

Conc. of adsorbed test mat.:

0.03 other: a.i. adsorbed on soil at equilibrium [µg/1 g]

pH:

6.8

Temp.:

20 °C

Remarks:

based on applied radioactivity / application solution: 0.004 mg/L

Computational methods:

The calculations were made according the following equations:

FREUNDLICH isotherm: x/m = Kd * C^1/n
with C: concentration of a.i. in solution at equilibrium, x/m: adsorbed amount of a.i. per weight unit of adsorbent (soil) at equilibrium (μg/g), Kd, n: constants (dimensionless)

After log-transformation the FREUNDLICH equation can be written as: log x/m = (1/n) * log C + log Kd

This equation describes a linear function with the term Kd describing the cross point of the linear graph and the ordinate. Based on the Kd-value the respective Koc-value is determined according to the following equation:

Koc = (Kd * 100) / %Corg
with Corg: portion of organic carbon in soil in % of weight

Sample No.:

#1

Type:

Kd

Remarks:

adsorption

Value:

47.35 L/kg

Temp.:

20 °C

Matrix:

Loamy sand

% Org. carbon:

1.99

Remarks on result:

other: 1/n = 0.9436

Sample No.:

#2

Type:

Kd

Remarks:

adsorption

Value:

11.65 L/kg

Temp.:

20 °C

Matrix:

Silt loam

% Org. carbon:

0.98

Remarks on result:

other: 1/n = 0.9083

Sample No.:

#3

Type:

Kd

Remarks:

adsorption

Value:

20.88 L/kg

Temp.:

20 °C

Matrix:

Sandy loam

% Org. carbon:

1.02

Remarks on result:

other: 1/n = 0.9105

Sample No.:

#4

Type:

Kd

Remarks:

adsorption

Value:

13.27 L/kg

Temp.:

20 °C

Matrix:

Silty clay

% Org. carbon:

1.09

Remarks on result:

other: 1/n = 0.9647

Sample No.:

#1

Type:

Koc

Remarks:

adsorption

Value:

2 380 L/kg

Temp.:

20 °C

Matrix:

Loamy sand

% Org. carbon:

1.99

Remarks on result:

other: 1/n = 0.9436

Key result

Sample No.:

#2

Type:

Koc

Remarks:

adsorption

Value:

1 189 L/kg

Temp.:

20 °C

Matrix:

Silt loam

% Org. carbon:

0.98

Remarks on result:

other: 1/n = 0.9083

Sample No.:

#3

Type:

Koc

Remarks:

adsorption

Value:

2 047 L/kg

Temp.:

20 °C

Matrix:

Sandy loam

% Org. carbon:

1.02

Remarks on result:

other: 1/n = 0.9105

Sample No.:

#4

Type:

Koc

Remarks:

adsorption

Value:

1 218 L/kg

Temp.:

20 °C

Matrix:

Silty clay

% Org. carbon:

1.09

Remarks on result:

other: 1/n = 0.9647

Sample No.:

#1

Type:

Kd

Remarks:

desorption

Value:

52.91 L/kg

Temp.:

20 °C

Matrix:

Loamy sand

% Org. carbon:

1.99

Remarks on result:

other: 1/n = 0.9316

Sample No.:

#2

Type:

Kd

Remarks:

desorption

Value:

13.61 L/kg

Temp.:

20 °C

Matrix:

Silt loam

% Org. carbon:

0.98

Remarks on result:

other: 1/n = 0.8895

Sample No.:

#3

Type:

Kd

Remarks:

desorption

Value:

27.89 L/kg

Temp.:

20 °C

Matrix:

Sandy loam

% Org. carbon:

1.02

Remarks on result:

other: 1/n = 0.9236

Sample No.:

#4

Type:

Kd

Remarks:

desorption

Value:

13.98 L/kg

Temp.:

20 °C

Matrix:

Silty clay

% Org. carbon:

1.09

Remarks on result:

other: 1/n = 0.9236

Sample No.:

#1

Type:

Koc

Remarks:

desorption

Value:

2 659 L/kg

Temp.:

20 °C

Matrix:

Loamy sand

% Org. carbon:

1.99

Remarks on result:

other: 1/n = 0.9316

Sample No.:

#2

Type:

Koc

Remarks:

desorption

Value:

1 389 L/kg

Temp.:

20 °C

Matrix:

Silt loam

% Org. carbon:

0.98

Remarks on result:

other: 1/n = 0.8895

Sample No.:

#3

Type:

Koc

Remarks:

desorption

Value:

2 734 L/kg

Temp.:

20 °C

Matrix:

Sandy loam

% Org. carbon:

1.02

Remarks on result:

other: 1/n = 0.9236

Sample No.:

#4

Type:

Koc

Remarks:

desorption

Value:

1 282 L/kg

Temp.:

20 °C

Matrix:

Silty clay

% Org. carbon:

1.09

Remarks on result:

other: 1/n = 0.9236

Adsorption and desorption constants:

For details see tables under "Any other information on result incl. tables" below

Recovery of test material:

For details see tables under "Any other information on result incl. tables" below

Concentration of test substance at end of adsorption equilibration period:

For details see tables under "Any other information on result incl. tables" below

Concentration of test substance at end of desorption equilibration period:

For details see tables under "Any other information on result incl. tables" below

Sample no.:

#1

Duration:

24 h

% Adsorption:

71.66

Remarks on result:

other: based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#1

Duration:

24 h

% Adsorption:

73.89

Remarks on result:

other: based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#1

Duration:

24 h

% Adsorption:

76.18

Remarks on result:

other: based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#1

Duration:

24 h

% Adsorption:

76.91

Remarks on result:

other: based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#2

Duration:

24 h

% Adsorption:

55.02

Remarks on result:

other: based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#2

Duration:

24 h

% Adsorption:

60.75

Remarks on result:

other: based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#2

Duration:

24 h

% Adsorption:

66.85

Remarks on result:

other: based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#2

Duration:

24 h

% Adsorption:

65.28

Remarks on result:

other: based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#3

Duration:

24 h

% Adsorption:

52.41

Remarks on result:

other: based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#3

Duration:

24 h

% Adsorption:

58.82

Remarks on result:

other: based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#3

Duration:

24 h

% Adsorption:

62.17

Remarks on result:

other: based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#3

Duration:

24 h

% Adsorption:

63.56

Remarks on result:

other: based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#4

Duration:

24 h

% Adsorption:

54.63

Remarks on result:

other: based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#4

Duration:

24 h

% Adsorption:

60.46

Remarks on result:

other: based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#4

Duration:

24 h

% Adsorption:

60.48

Remarks on result:

other: based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#4

Duration:

24 h

% Adsorption:

59.34

Remarks on result:

other: based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#1

Duration:

24 h

% Desorption:

24.39

Remarks on result:

other: based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#1

Duration:

24 h

% Desorption:

23.08

Remarks on result:

other: based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#1

Duration:

24 h

% Desorption:

20.62

Remarks on result:

other: based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#1

Duration:

24 h

% Desorption:

18.85

Remarks on result:

other: based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#2

Duration:

24 h

% Desorption:

36.82

Remarks on result:

other: based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#2

Duration:

24 h

% Desorption:

33.07

Remarks on result:

other: based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#2

Duration:

24 h

% Desorption:

27.49

Remarks on result:

other: based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#2

Duration:

24 h

% Desorption:

25.76

Remarks on result:

other: based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#3

Duration:

24 h

% Desorption:

38.5

Remarks on result:

other: based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#3

Duration:

24 h

% Desorption:

33.98

Remarks on result:

other: based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#3

Duration:

24 h

% Desorption:

32.29

Remarks on result:

other: based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#3

Duration:

24 h

% Desorption:

29.76

Remarks on result:

other: based on applied radioactivity / application solution: 0.004 mg/L

Sample no.:

#4

Duration:

24 h

% Desorption:

39.16

Remarks on result:

other: based on applied radioactivity / application solution: 0.525 mg/L

Sample no.:

#4

Duration:

24 h

% Desorption:

35.87

Remarks on result:

other: based on applied radioactivity / application solution: 0.114 mg/L

Sample no.:

#4

Duration:

24 h

% Desorption:

33.24

Remarks on result:

other: based on applied radioactivity / application solution: 0.023 mg/L

Sample no.:

#4

Duration:

24 h

% Desorption:

30.69

Remarks on result:

other: based on applied radioactivity / application solution: 0.004 mg/L

Transformation products:

not measured

Details on results (Batch equilibrium method):

Orientating tests details
- Stability of the test item in test solution: The stability with and without soil in 0.01 M calcium chloride solution was confirmed within the orientating test performed to determine the equilibration time.
- Soil/solution ratio: Using ratios of 1g soil and 20 mL solution (BBA 2.2 and Laacher Hof AXXa) and 2 g soil and 20 mL solution (Laacher Hof A III and LUFA Speyer) the percent of radioactivity adsorbed to the soils was found to be within the recommended range resp. from 27.9% to 47.8%. This was the justification to use these soil/solution ratios for the definitive test.
- Equilibration time: Equilibrium was reached after shaking for 24 h. The changes in concentrations in the supernatant were less than 5% from 24 h to 48 h as recommended. In the control samples approximately 20% of the test item was adsorbed to the wall of the Teflon vessels. Degradation of test item depending on the equilibration time was determined by HPLC. After 24 h no significant degradation products could be detected in the supernatant. Thus the definitive test was performed using a shaking period of 24 h.
- Adsorption to test vessels: Approximately 20% of the test item was again adsorbed to the Teflon® wall within 10 minutes. Using glass vessels no significant absorption was measured.

Definitive study details:
- As result of the preliminary studies the definitive study was performed using glass vessels and an equilibration time of 24 h for adsorption and 24 h for desorption. For the definitive study fresh application solutions were prepared from the stock solutions. Samples were shaken in the dark at room temperature (approximately 20 °C). Before the test purity of the application solutions and radioactivity were determined using thin-layer chromatography and LSC.
- Adsorption measurements: The adsorption behaviour of the test item in the concentration range of two orders of magnitude from 0.004 mg/L to 0.525 mg/L is accurately described for all soils with the FREUNDLICH equation. The correlation coefficients of the individual isotherms are r ≥ 0.9988. The sequence of the adsorption isotherms and the distances between each other reflect the graduation of the soils with regard to their adsorption potential for the test item.
The adsorption constants Kd(ads) of the FREUNDLICH isotherms for the four test soils range from 11.65 mL/g to 47.35 mL/g. The FREUNDLICH exponents 1/n are close below 1. This means that the percentage of adsorbed test substance barely decreases with increasing applied concentrations. In general the organic matter in soil, determined as organic carbon, is the most important part to bind organic chemicals. Therefore the adsorption coefficients Kd(ads) are correlated with the organic carbon content of the soil for a better comparability of the adsorption behaviour in different soils. In case of the test item the calculated Koc(ads)-values vary between 1,189 mL/g and 2,380 mL/g. This result indicates that the adsorption behaviour of the test item is mainly determined by the humus content.
Between 52.4% and 76.9% of the applied test item were adsorbed to soil. Using thin-layer chromatography the purity of the application solutions A – B was determined to be ≥ 98.3% before application to the soils. The thin-layer chromatographic examination of the clear supernatants of samples after establishing of equilibration showed that more than 91.3% of the radioactivity in solution could be assigned to the unchanged test substance.
- Desorption measurements: The desorption constants Kd(des) range from 13.61 mL/g of the soil Laacher Hof A III to 52.91 mL/g of the soil BBA 2.2. The Koc(des) values of the soils are in a range from 1,389 mL/g to 2,659 mL/g with a range of 1/n values from 0.8895 to 0.9316. The Koc(des) values are in the same range compared to the corresponding Koc(ads)-values derived from the adsorption measurements. A single desorption step using 0.01 M calcium chloride solution results in the liberation a portion of between 18.85 % (BBA 2.2) and 39.16 % (LUFA Speyer) of the adsorbed radioactivity.
- Conclusion: The adsorption constants Kd(ads) calculated for the test item from the FREUNDLICH isotherms for the four test soils range from 11.65 mL/g to 47.35 mL/g. The respective Koc(ads)-values range from 1,189 mL/g to 2,380 mL/g. Based on classifications of McCall et al. (Measurement of sortion coefficients of organic chemicals and their use in environmental fate analysis, Test protocols for environmental fate and movement of toxicants, AOAC, 94th Annual Meeting, October 21-22, 1980) for the estimation of the mobility of plant protectants in soil based on Kd and/or Koc-values, the test item is to be classified as a substance with low to slight mobility.

Table 1: Weights of soils used in adsorption/desorption experiments

Soil	1	2	3	4
Name	BBA 2.2	Laacher Hof AIII	Laacher Hof AXXa	LUFA Speyer
Type	Loamy sand	Silt loam	Sandy loam	Silty clay
org. C (%)	1.99	0.98	1.02	1.09
Soil dry weight [g]	0.9867	1.973	0.9913	1.932
Solution volumes [mL]*	20.27	20.27	20.17	20.68

*Corrected by soil water content

Table 2: Applied radioactivity / Concentrations of the test item used in adsorption/desorption experiments

Application solution	Aliquot [mL]	Single values [Bq/aliquot]			RA appl. [Bq/20mL]
A: 0.525 mg/L	0.5	1,110	1,148	1,133	45,214
B: 0.114 mg/L	0.5	243.7	243.8	247.8	9,803
C: 0.023 mg/L	0.5	50.29	50.32	51.00	2,021
D: 0.004 mg/L	0.5	8.98	9.12	9.22	364.3

 

Table 3: Calculation of adsorption experiments for the test item on the four soils used

	[μg/20 mL] applied a.i.	a.i. in solution at equilibrium [μg/20 mL]	a.i. in solution at equilibrium [μg/20 mL]	a.i. adsorbed in % of applied	ln (x/m) [μg/g]	ln (C) [μg/mL]
Soil #1: BBA 2.2
A: 0.525 mg/L	10.49	2.97 ± 0.08	7.52 ± 0.08	71.66	2.03	-1.92
B: 0.114 mg/L	2.27	0.59 ± 0.00	1.68 ± 0.00	73.89	0.53	-3.53
C: 0.023 mg/L	0.47	0.11 ± 0.00	0.36 ± 0.00	76.18	-1.02	-5.20
D: 0.004 mg/L	0.08	0.02 ± 0.00	0.07 ± 0.00	76.91	-2.72	-6.95
Soil #2: Laacher Hof A III
A: 0.525 mg/L	10.49	4.72 ± 0.02	5.77 ± 0.02	55.02	1.07	-1.46
B: 0.114 mg/L	2.27	0.89 ± 0.00	1.38 ± 0.00	60.75	-0.36	-3.12
C: 0.023 mg/L	0.47	0.16 ± 0.01	0.31 ± 0.01	66.85	-1.84	-4.87
D: 0.004 mg/L	0.08	0.03 ± 0.00	0.06 ± 0.00	65.28	-3.58	-6.54
Soil #3: Laacher Hof AXXa
A: 0.525 mg/L	10.49	4.99 ± 0.13	5.50 ± 0.13	52.41	1.71	-1.40
B: 0.114 mg/L	2.27	0.94 ± 0.01	1.34 ± 0.01	58.82	0.30	-3.07
C: 0.023 mg/L	0.47	0.18 ± 0.00	0.29 ± 0.00	62.17	-1.22	-4.73
D: 0.004 mg/L	0.08	0.03 ± 0.00	0.05 ± 0.00	63.56	-2.92	-6.48
Soil #4: Lufa Speyer
A: 0.525 mg/L	10.49	4.76 ± 0.01	5.73 ± 0.01	54.63	1.09	-1.47
B: 0.114 mg/L	2.27	0.90 ± 0.05	1.38 ± 0.05	60.46	-0.34	-3.14
C: 0.023 mg/L	0.47	0.19 ± 0.00	0.28 ± 0.00	60.48	-1.92	-4.71
D: 0.004 mg/L	0.08	0.03 ± 0.00	0.05 ± 0.00	59.34	-3.65	-6.40

 

Table 4: Calculation of desorption experiments for the test item on the four soils used

	a.i. adsorbed on soil at equilibrium [μg/1 g]	a.i. in solution at equilibrium [μg/20 mL]	a.i. adsorbed on after desorption [μg/1 g]	a.i. desorbed in % of adsorbed	ln (x/m) [μg/g]	ln (C) [μg/mL]
Soil #1: BBA 2.2
A: 0.525 mg/L	6.61 ± 0.06	1.61 ± 0.07	5.00 ± 0.07	24.39	1.62	-2.53
B: 0.114 mg/L	1.48 ± 0.01	0.34 ± 0.01	1.14 ± 0.01	23.08	0.14	-4.08
C: 0.023 mg/L	0.31 ± 0.00	0.06 ± 0.00	0.25 ± 0.00	20.62	-1.39	-5.76
D: 0.004 mg/L	0.06 ± 0.00	0.01 ± 0.00	0.05 ± 0.00	18.85	-3.00	-7.48
Soil #2: Laacher Hof A III
A: 0.525 mg/L	4.82 ± 0.02	1.77 ± 0.02	3.04 ± 0.02	36.82	0.43	-2.44
B: 0.114 mg/L	1.16 ± 0.00	0.38 ± 0.01	0.77 ± 0.01	33.07	-0.94	-3.97
C: 0.023 mg/L	0.25 ± 0.00	0.07 ± 0.00	0.18 ± 0.00	27.49	-2.37	-5.67
D: 0.004 mg/L	0.05 ± 0.00	0.01 ± 0.00	0.04 ± 0.00	25.76	-3.96	-7.35
Soil #3: Laacher Hof AXXa
A: 0.525 mg/L	4.65 ± 0.18	1.79 ± 0.17	2.86 ± 0.17	38.50	1.06	-2.42
B: 0.114 mg/L	1.14 ± 0.02	0.39 ± 0.02	0.75 ± 0.02	33.98	-0.27	-3.95
C: 0.023 mg/L	0.23 ± 0.00	0.08 ± 0.00	0.16 ± 0.00	32.29	-1.84	-5.59
D: 0.004 mg/L	0.05 ± 0.00	0.01 ± 0.00	0.03 ± 0.00	29.76	-3.42	-7.30
Soil #4: Lufa Speyer
A: 0.525 mg/L	4.72 ± 0.11	1.85 ± 0.10	2.87 ± 0.10	39.16	0.40	-2.41
B: 0.114 mg/L	1.11 ± 0.01	0.40 ± 0.00	0.71 ± 0.00	35.87	-1.00	-3.95
C: 0.023 mg/L	0.24 ± 0.00	0.08 ± 0.00	0.16 ± 0.00	33.24	-2.51	-5.58
D: 0.004 mg/L	0.05 ± 0.00	0.01 ± 0.00	0.03 ± 0.00	30.69	-4.09	-7.27

 

Table 5: Distribution of radioactivity for the test item on the four soils used (Balance in % of the applied radioactivity; Mean and difference of the individual values calculated from two test batches)

	adsorption solution [%]	desorption solution [%]	soil combustion [%]	Recovery [%]
Soil #1: BBA 2.2
A: 0.525 mg/L	27.03 ± 0.72	16.06 ± 0.01	48.23 ± 0.48	91.32 ± 0.23
B: 0.114 mg/L	24.93 ± 0.06	15.44 ± 0.18	50.74 ± 0.49	91.10 ± 0.24
C: 0.023 mg/L	22.67 ± 0.84	14.06 ± 0.35	53.09 ± 0.97	89.82 ± 0.22
D: 0.004 mg/L	22.00 ± 0.68	13.88 ± 0.05	58.76 ± 0.59	94.64 ± 0.14
Soil #2: Laacher Hof A III
A: 0.525 mg/L	41.96 ± 0.01	18.90 ± 0.07	30.05 ± 0.26	90.90 ± 0.33
B: 0.114 mg/L	36.76 ± 0.31	17.91 ± 0.21	35.39 ± 0.25	90.06 ± 0.28
C: 0.023 mg/L	30.78 ± 0.98	16.13 ± 0.46	40.58 ± 0.89	87.49 ± 0.56
D: 0.004 mg/L	32.41 ± 0.52	16.45 ± 0.20	45.58 ± 0.08	94.43 ± 0.63
Soil #3: Laacher Hof AXXa
A: 0.525 mg/L	45.70 ± 1.20	18.17 ± 0.00	28.01 ± 1.66	91.88 ± 0.47
B: 0.114 mg/L	39.57 ± 0.34	17.86 ± 0.01	33.99 ± 0.84	91.42 ± 0.52
C: 0.023 mg/L	36.37 ± 0.69	16.74 ± 0.10	34.44 ± 0.66	87.55 ± 1.26
D: 0.004 mg/L	35.03 ± 0.19	16.74 ± 0.10	39.10 ± 1.00	90.87 ± 0.90
Soil #4: Lufa Speyer
A: 0.525 mg/L	40.48 ± 0.07	20.01 ± 0.16	29.91 ± 0.90	90.39 ± 1.13
B: 0.114 mg/L	35.24 ± 2.13	19.67 ± 0.05	33.60 ± 0.08	88.50 ± 2.00
C: 0.023 mg/L	35.16 ± 0.26	18.81 ± 0.04	35.76 ± 0.22	89.74 ± 0.52
D: 0.004 mg/L	36.12 ± 0.51	19.07 ± 0.02	40.81 ± 1.41	96.00 ± 0.92

 

Table 6: FREUNDLICH constants

Adsorption
Soil Designition	Soil Type	ln Kd	Kd [mL/g]	1/n	Koc [mL/g]	r
BBA 2.2	Loamy sand	3.8576	47.35	0.9436	2,380	0.9999
Laacher Hof AIII	Silt loam	2.4555	11.65	0.9083	1,189	0.9988
Laacher Hof AXXa	Sandy loam	3.0386	20.88	0.9105	2,047	0.9995
LUFA Speyer	Silty clay	2.5857	13.27	0.9647	1,218	0.9991
Desorption
BBA 2.2	Loamy sand	3.9687	52.91	0.9316	2,659	1.0000
Laacher Hof AIII	Silt loam	2.6107	13.61	0.8895	1,389	0.9997
Laacher Hof AXXa	Sandy loam	3.3282	27.89	0.9236	2,734	0.9998
LUFA Speyer	Silty clay	2.6376	13.98	0.9236	1,282	1.0000

 

Validity criteria fulfilled:

not applicable

Description of key information

The Koc (adsorption) at 20 °C was determined to be in the range of 1189 to 2380 L/kg (batch equilibrium method, OECD 106).

Additional information

One study is available testing the adsorption / desorption behaviour of the test substance using the batch equilibrium method (1999). The test conducted according to OECD guideline 106 and under GLP standards. Four different soils were used and the test item was 14C-labeled. As result of the preliminary studies the definitive study was performed using glass vessels and an equilibration time of 24 h for adsorption and 24 h for desorption. Samples were shaken in the dark at room temperature (approximately 20 °C). Before the test, purity of the application solutions and radioactivity were determined using thin-layer chromatography and LSC.

For the test substance the adsorption process in the concentration range studied (0.004-0.5 mg a.i./L 0.01 M CaCl2) can be described with high accuracy (r ≥ 0.9988) by the FREUNDLICH equation for all four test soils. The percentage of adsorption of parent compound varied between 52.4% and 76.9% of applied a.i. depending on soil type and concentration. The soil/solvent ratios were 1/20 and 1/10.

Depending on the test soil the following FREUNDLICH constants (Kd(ads), 1/n) as well as the Koc(ads)-values were determined for the adsorption measurements:

Adsorption
Soil Designition	Soil Type	Organic carbon (%)	ln Kd	Kd [L/kg]	1/n	Koc [L/kg]	r
#1: BBA 2.2	Loamy sand	1.99	3.8576	47.35	0.9436	2380	0.9999
#2: Laacher Hof AIII	Silt loam	0.98	2.4555	11.65	0.9083	1189	0.9988
#3: Laacher Hof AXXa	Sandy loam	1.02	3.0386	20.88	0.9105	2047	0.9995
#4: LUFA Speyer	Silty clay	1.09	2.5857	13.27	0.9647	1218	0.9991

The values close to 1 determined for 1/n indicate that for the total range of concentrations tested the concentration of active ingredient had no influence on the distribution between dissolved and adsorbed test item.

With a single desorption step using 0.01 M calcium chloride solution, 18.8% to 39.1% of adsorbed a.i. could again be desorbed. The parameters for the FREUNDLICH desorption isotherms as well as the resulting Koc(des)-values are as follows:

Desorption
Soil Designition	Soil Type	Organic carbon (%)	ln Kd	Kd [L/kg]	1/n	Koc [L/kg]	r
#1: BBA 2.2	Loamy sand	1.99	3.9687	52.91	0.9316	2659	1.0000
#2: Laacher Hof AIII	Silt loam	0.98	2.6107	13.61	0.8895	1389	0.9997
#3: Laacher Hof AXXa	Sandy loam	1.02	3.3282	27.89	0.9236	2734	0.9998
#4: LUFA Speyer	Silty clay	1.09	2.6376	13.98	0.9236	1282	1.0000

Thus, the test item can be classified as a substance with low to slight mobility.

In addition further data on adsorption are available from a short summary (1997). The limited data provided therein is not sufficient enough to be considered for assessment purposes. However, in order to provide all available data, the information is shortly summarised here. The study was conducted according to OECD guideline 106. Adsorption in four types of standard soils was studied with the radiolabeled compound. Organic carbon content (OC%) of the four soils were 3.18%, 1.22%, 2.60%, and 1.56%. Adsorption coefficients (K) were 22.1, 40.8, 13.0 and 12. Koc (K/(OC%/100)) were 695, 3344, 500 and 782, respectively.