Benzamide, N-[[4-[(cyclopropylamino)carbonyl]phenyl]sulfonyl]-2-methoxy-

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:

14 Jul 2003 - 01 Jul 2004

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: EPA Pesticide Assessment Guidelines, Subdivision N, § 163-1, Leaching and Adsorption/Desorption Studies (Oct 18, 1982)

Qualifier:

according to guideline

Guideline:

other: Environmental Chemistry and Fate Guidelines for Registration of Pesticides in Canada. Agriculture Canada Trade Memorandum T-1-255, Section 6.2.B.1, Adsorption-Desorption Measurements (Jul 15, 1987)

GLP compliance:

yes (incl. QA statement)

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

yes

Test temperature:

20 ± 1 °C

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0.6, 0.2, 0.06, 0.02, and 0.006 mg/L
- Sampling interval: 24 hours for adsorption equilibration (all samples), 24 hours for desorption equilibration (all samples)
and further 2x24 hours consecutive desorption cycles (highest test concentration samples only)
- Sample storage before analysis:

Matrix no.:

#1

Matrix type:

sandy loam

% Clay:

5

% Silt:

22.6

% Sand:

72.4

% Org. carbon:

1.47

pH:

6.3

CEC:

10.3 meq/100 g soil d.w.

Matrix no.:

#2

Matrix type:

silt loam

% Clay:

12

% Silt:

51.1

% Sand:

36.9

% Org. carbon:

0.88

pH:

6.8

CEC:

9.8 meq/100 g soil d.w.

Matrix no.:

#3

Matrix type:

Silt

% Clay:

10.2

% Silt:

81.3

% Sand:

8.5

% Org. carbon:

1.56

pH:

6.2

CEC:

13.9 meq/100 g soil d.w.

Matrix no.:

#4

Matrix type:

silt loam

% Clay:

19

% Silt:

62

% Sand:

19

% Org. carbon:

4.1

pH:

7.4

CEC:

26 meq/100 g soil d.w.

Bulk density (g/cm³):

0.9

Matrix no.:

#5

Matrix type:

silty clay

% Clay:

45.3

% Silt:

51.7

% Sand:

3

% Org. carbon:

1.15

pH:

4.8

CEC:

23.1 meq/100 g soil d.w.

Bulk density (g/cm³):

1.11

Matrix no.:

#6

Matrix type:

loamy sand

% Clay:

7

% Silt:

12

% Sand:

82

% Org. carbon:

1

pH:

5.5

CEC:

4.5 meq/100 g soil d.w.

Bulk density (g/cm³):

1.36

Matrix no.:

#7

Matrix type:

sandy loam

% Clay:

8.5

% Silt:

29.2

% Sand:

62.3

% Org. carbon:

1.02

pH:

6.3

CEC:

10 meq/100 g soil d.w.

Bulk density (g/cm³):

1.34

Details on matrix:

COLLECTION AND STORAGE
- Geographic location: Seven test soils were used in this study:
AXXa (LaacherHof, Field Plot 'AXXa') origin EU
Alll (Laacher Hof, Field Plot'AM') origin EU
HAH (Hoefchen am Hohenseh, Field Plot '4A') origin EU
BBA2.3 (LUFA Speyer, BBA Standard Soil Type 2.3) origin EU
HCB (Horse Camp Bridge) origin US
SSC (Stanley Silty Clay) origin US
PKV (Pikeville Loamy Sand) origin US

- Collection procedures: Field sampled with showel into pot
- Sampling depth (cm): 0 - 20 cm
- Storage conditions: at ca. 5°C, in bucket
- Storage length: differ from soil to soil
- Soil preparation: The soils were sieved to < 2 mm particle size and air-dried at ambient temperature.

SOIL PROPERTIES: see table under "results"

Details on test conditions:

TEST SYSTEM
- Type, size and further details on reaction vessel: Teflon® Centrifuge tubes with plastic screw cap (equipped with a Teflon®-coated rubber septum), volume ca. 43 mL
- Number of reaction vessels/concentration: 2
- Soil/solution ratio: 1:1 w/w for all soils in adsorption step (20 g soil dry matter, 20 g solution) and 1:1.5 w/w for all soils in desorption steps (20 g soil dry matter, 30 g solution)

Duration:

24 h

Initial conc. measured:

>= 0.006 - <= 0.6 other: mg/L

Temp.:

20 °C

Computational methods:

- Freundlich adsorption and desorption coefficients: Calculation according to OECD 106
- Adsorption coefficient per organic carbon (Koc): based on Freundlich Kf-value, the respective Freundlich Koc-value was determined.

Sample No.:

#1

Type:

Koc

Value:

12.2 L/kg

pH:

6.3

Temp.:

20 °C

% Org. carbon:

1.47

Remarks on result:

other: soil 1

Remarks:

AXXa

Sample No.:

#2

Type:

Koc

Value:

7.9 L/kg

pH:

6.8

Temp.:

20 °C

% Org. carbon:

0.88

Remarks on result:

other: soil 2

Remarks:

AIII

Sample No.:

#3

Type:

Koc

Value:

9.2 L/kg

pH:

6.2

Temp.:

20 °C

% Org. carbon:

1.56

Remarks on result:

other: soil 3

Remarks:

HAH

Sample No.:

#4

Type:

Koc

Value:

11 L/kg

pH:

7.4

Temp.:

20 °C

% Org. carbon:

4.1

Remarks on result:

other: soil 4

Remarks:

HCB

Sample No.:

#5

Type:

Koc

Value:

75.4 L/kg

pH:

4.8

Temp.:

20 °C

% Org. carbon:

1.15

Remarks on result:

other: soil 5

Remarks:

SSC

Sample No.:

#6

Type:

Koc

Value:

69.7 L/kg

pH:

5.5

Temp.:

20 °C

% Org. carbon:

1

Remarks on result:

other: soil 6

Remarks:

PKV

Sample No.:

#7

Type:

Koc

Value:

20.3 L/kg

pH:

6.3

Temp.:

20 °C

% Org. carbon:

1.02

Remarks on result:

other: soil 7

Remarks:

BBA2.3

Sample No.:

#1

Type:

log Koc

Value:

1.09 L/kg

pH:

6.3

Temp.:

20 °C

% Org. carbon:

1.47

Remarks on result:

other: soil 1,

Remarks:

AXXa

Sample No.:

#2

Type:

log Koc

Value:

0.9 L/kg

pH:

6.8

Temp.:

20 °C

% Org. carbon:

0.88

Remarks on result:

other: soil 2

Remarks:

AIII

Sample No.:

#3

Type:

log Koc

Value:

0.96 L/kg

pH:

6.2

Temp.:

20 °C

% Org. carbon:

1.56

Remarks on result:

other: soil 3

Remarks:

HAH

Sample No.:

#4

Type:

log Koc

Value:

1.04 L/kg

pH:

7.4

Temp.:

20 °C

% Org. carbon:

4.1

Remarks on result:

other: soil 4

Remarks:

HCB

Sample No.:

#5

Type:

log Koc

Value:

1.88 L/kg

pH:

4.8

Temp.:

20 °C

% Org. carbon:

1.15

Remarks on result:

other: soil 5

Remarks:

SSC

Sample No.:

#6

Type:

log Koc

Value:

1.84 L/kg

pH:

5.5

Temp.:

20 °C

% Org. carbon:

1

Remarks on result:

other: soil 6

Remarks:

PKV

Sample No.:

#7

Type:

log Koc

Value:

1.31 L/kg

pH:

6.3

Temp.:

20 °C

% Org. carbon:

1.02

Remarks on result:

other: soil 7

Remarks:

BBA2.3

Recovery of test material:

90 -97%

Referring to the mean values per test soil the recovery of RA* was in the range of 94% - 97% of theoretical applied for the test systems of soils AXXa, AIM, HAH, PKV, and BBA2.3. No signs of systematic losses of radioactivity were observed for these soils. The complete material balance demonstrated that no significant amount of RA dissipated from the test vessels or was lost upon processing.
For soils HCB and SSC, however, the mean material balance was 90% of applied. A trend became apparent for individual vessel deficits eventually exceeding 10% at the test concentrations B to E, whilst for both soils the material balances of the test concentration A samples were well within range (94 / 97% AR). Such effect may be explained by easy microbial mineralisation of the test item to form volatile 14CO2 in aerobic soil, leading to losses during the very slow air-drying process at ambient temperature for these two high clay or high organic matter soils.

* For this study the applied radioactivity (AR = 100% of RA) was defined as the amount of radioactivity contained in 2 ml of the respective application solutions.

Transformation products:

not measured

Details on results (Batch equilibrium method):

MAIN TEST: PERFORMANCE
- Test material stability during adsorption/desorption phase: stable
- Experimental conditions maintained throughout the study: Yes
- Buffer/test substance interactions affecting sorption: No

Conclusions:

The adsorption coefficients KFof AE 0001789 on the seven test soils ranged from 0.07 mL/g to 0.87 mL/g, as derived from FREUNDLICH isotherm evaluation. The corresponding organic carbon normalised adsorption coefficients (KFoc values) were12.2 mL/g, 7.9 mL/g, 9.2 mL/g, 11.0 mL/g, 75.4 mL/g, 69.7 mL/g, and 20.3 mL/g.

With respect to the soil physico-chemical properties, a trend of higher adsorption of AE 0001789 on soils of acidic pH became apparent. Such behavior is inline with the acidic nature of the test item.

Results:

The percentage of adsorption of AE 0001789 on soils in the Definitive Test varied between 6.6% and 69.6% of the applied amount, whilst blank controls without soil proved absence of significant adsorption on the test vessel inner surfaces. Chromatography analysis of supernatant solutions from all soils demonstrated >90% parent stability after adsorption and desorption. Total radioactive recovery ranged from 90% to 97% of the applied radioactivity (mean values per soil).

Soil				AXXa				AIM				HAH					HCB					SSC	PKV	BBA2.3
texture(USDA criteria)				sandy loam				silt loam				silt					silt loam					silty clay	loamy sand	sandy loam
clay[%]				5				12				10					19					45	7	9
pH(in CaCI2)				6.3				6.8				6.2					7.4					4.8	5.5	6.3
CEC[meq/100g]				10.3				9.8				13.9					26.0					23.1	4.5	10.0
org. C[%]				1.5				0.9				1.6					4.1					1.2	1.0	1.0
FREUNDLICH parameters of AE 0001789 adsorption on soil:
KF			0.18						0.07		0.14					0.45					0.87		0.70	0.21
Kp,oc			12.2						7.9		9.2					11.0					75.4		69.7	20.3
1/n			0.92						0.84		0.86					0.83					0.84		0.86	0.90
FREUNDLICH parameters of AE 0001789 desorption from soil:
KF		1.90					1.16			2.25			3.99							1.90			1.96	2.02
KF,OC		129			132					144				97				165					196	198
1/n	0.98					0.87				0.95					0.92				0.82				0.86	0.93

The organic carbon normalised adsorption coefficients (KF,oc values), as derived from a FREUNDLICH evaluation, varied between 7.9 - 75.4 mL/g for adsorption, or between 97.2 - 198.3 mL/g for desorption (see Table above). Comparison of KF,oc

calculated for the adsorption and the desorption steps revealed a significant difference in value. This suggests, that the test item once adsorbed to soil is not readily desorbed.

For the set of tested soils, an increase in KF,oc of AE 0001789 at lower soil pH became apparent. This is in-line with the acidic nature of the test item. FREUNDLICH exponents (1/n) smaller 1.0 indicated a slight concentration dependency, with favored soil adsorption of AE 0001789 at lower concentrations. On the basis of this study, the soil mobility class (according to BRIGGS) of

AE 0001789 is 'mobile' to 'intermediate' in case of adsorption, or 'intermediate' to 'low' in case of desorption.

Validity criteria fulfilled:

not applicable

Description of key information

 Koc: 7.9 - 75.4 mL/g (OECD 106) 

Key value for chemical safety assessment

Koc at 20 °C:

75.4

Additional information

The potential for mobility of Cyprosulfamide in soil can be indicated on the basis of their sorption constants. One GLP study was conducted using the batch equilibrium method according to OECD Guideline 106 (M-123114-01-2). Freundlich adsorption constants normalized to the organic carbon (OC) content KF,OC were determined for the test substance in seven soils with values ranging from 7.9 to 75.4 mL/g (log Koc = 0.9 - 1.88 mL/g). The data indicated a correlation with the soil pH, i.e. the lower the soil pH the higher the sorption constant.