diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

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

Study period:

10 Dec 1991 - 02 Jun 1992

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)

GLP compliance:

yes

Type of method:

batch equilibrium method

Media:

soil

Details on study design: HPLC method:

EQUIPMENT
- Apparatus:

Analytical monitoring:

yes

Details on matrix:

see table below

Details on test conditions:

Test solutions:
Using a stock solution of the test substance (1 g/1 in acetonitrile) the following dilutions in
autoclaved 0.01 M CaCl2-solution were prepared (nom. values): 5 mg/1 for kinetics; 5, 1, 0.2 and
0.05 mg/1 for adsorption/desorption. Confirmation of the content using HPLC: 4.9 mg/1 for kinetics;
5.1, 0.7, 0.15 and 0.05 mg/1 for adsorption/desorption. The dilutions were prepared under laminar
flow conditions.

Computational methods:

- Adsorption and desorption coefficients (Kd):The adsorption and desorption parameters were calculated from measurements by the application of the Freundlich approach.

Type:

Koc

Value:

>= 486 - <= 823

Findings:

The K_OC-values along with key soil parameters are summarized in the table below:

No formation of degradation products was observed in the course of the study. The desorption coefficients were slightly higher than the adsorption coefficients, indicating a hysteresis effect for the adsorption/desorption process with a possibly irreversible binding of the substance to the soil matrix.

 

Summary of adsorption coefficients of AE F107892

Soil	pH	Organic Carbon [%]	Kf, ads [mL/g]	KOC [mL/g]	1/n
Silt Loam (SLH)	6.2	1.10	7.08	644	0.99
Sandy Loam (SLV)	5.8	1.13	6.71	593	1.20
Sand (S2.1)	5.0	1.17	5.68	486	1.20
Loamy Sand (LS2.2)	5.0	2.91	23.96	823	1.23
Loamy Sand (LSN)	7.1	0.89	5.16	580	1.20

 

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

supporting 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)

Qualifier:

according to guideline

Guideline:

other: USEPA (= EPA) Subdiv. N (1982)

Principles of method if other than guideline:

Study design reflects both EPA and OECD (Section 106, 1981;2 proposed Section 1063, 19964) guidelines.

GLP compliance:

yes

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

yes

Analytical monitoring:

yes

Type:

Koc

Value:

>= 678 - <= 738

Findings:

The equilibrium in the soil/water system was established after approx. 8 hours.

AE F107892 was found to be stable under sterile conditions with above 90% of the residue recovered in the soil and water portions after 72 hours identified as AE F107892.

The calculated adsorption constants KF(ads) of the Freundlich isotherm along with the Freundlich exponent 1/n are summarized in the table below:

 

 Summary of adsorption coefficients of AE F107892

Soil	pH	Organic Carbon [%]	Kf, ads [mL/g]	KOC [mL/g]	1/n
Sand (NC, US)	5.0	0.49	3.16	648	0.96
Sandy Clay Loam (ND, US)	7.4	2.70	19.9	738	0.96

 

Conclusion:

The results indicate a medium to well adsorption to all soils. Mefenpyr-diethyl AE F107892 is therefore of low mobility in soil. Consequently, there is a reduced risk of leaching into deeper layers of soil.

 

Description of key information

The Koc (adsorption) at 20 °C was determined to be in the range of 486 to 823 mL/g (batch equilibrium method, OECD 106). 

Key value for chemical safety assessment

Koc at 20 °C:

486

Additional information

The adsorption/desorption behaviour of the substances was tested in a guideline study following OECD guideline 106 (1992). The test was conducted with five different soils (Silt Loam, Sandy Loam, Sand, and two types of Loamy Sand). The Koc values ranged from 486 to 823 depending on soil type.

Comparable results were determined in a supporting study following OECD guideline 106 investigating the adsorption/desorption behaviour in sand and sandy clay loam (1997). The determined Koc values were 648 mL/g in sand and 738 mL/g in sandy clay loam respectively.