Ferbam

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:

1997-09-16 - 1997-09-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

other: no guideline available

Principles of method if other than guideline:

The extent of adsorption of chemical onto sediment or soil is measured by equilibrating chemicals aqueous solutions with different quantities of sediment or soil. After steady-state is reached, the distribution of chemical between the water phase and the solid phase is quantitatively measured by a suitable analytical method.

GLP compliance:

no

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

yes

Test temperature:

25.0 °C

Analytical monitoring:

not specified

Details on sampling:

see 'Any other information on materials and methods incl. tables'

Details on matrix:

see 'Any other information on materials and methods incl. tables'

Details on test conditions:

see 'Any other information on materials and methods incl. tables'

Remarks:

see 'Any other information on materials and methods incl. tables'

Remarks:

see 'Any other information on materials and methods incl. tables'

Computational methods:

see 'Any other information on materials and methods incl. tables'

Sample No.:

#1

Type:

Koc

Value:

53.4 dimensionless

Sample No.:

#2

Type:

Koc

Value:

11.9 dimensionless

Sample No.:

#3

Type:

Koc

Value:

8.3 dimensionless

Adsorption and desorption constants:

see 'Any other information on results incl. tables'

Recovery of test material:

not specified

Concentration of test substance at end of adsorption equilibration period:

not specified

Concentration of test substance at end of desorption equilibration period:

not specified

Sample no.:

#1

% Adsorption:

93

Sample no.:

#2

% Adsorption:

70

Sample no.:

#3

% Adsorption:

60

Transformation products:

not specified

Details on results (Batch equilibrium method):

see 'Any other information on results incl. tables'

Statistics:

see 'Any other information on results incl. tables'

Table 2 shows the results of radioactivity from samples for the adsorption/desorption experiment with GH, LR and LE soils. Table 3 shows average values for the equilibrium concentrations (Ce) in solutions, and Table 4 shows the average values for the total amount of test substance in these soils. Table 5 shows the equations of Freundlich isotherms, coefficients of adsorption (K) and coefficient for soil organic matter (Koc). Table 6 shows the adsorption/desorption classification of chemical, according to MHM/SEMA.

According to the Table 4, the total amount of the test substance ferbam adsorbed on GH soil was about 93%. On LR soil was about 70%, and on LE soil 60%. The coefficients of adsorption and desorption from GH soil were 53.4 and 257.4, from LR soil were 11.9 and 19.7, and from LE soil these coefficients were 8.3 and 42.6, respectively.

Table 2: Results of radioactivity in disintegration per minute (dpm) in the experiment using 5 concentrations of test substance and standard on GH, LR and LE soils (2 replicates).

Solution (ug / mL)	GH		LR		LE		Standard
	Ads.	Des.	Ads.	Des.	Ads.	Des.
0,5	2859	1057	10385	3040	15980	4845	62238
	2887	977	9395	2436	15988	4711
1,0	2903	1011	8402	2479	14625	4610	58055
	2931	1046	8548	2520	14726	4604
5,0	2895	1181	10084	2333	17438	3501	56301
	2906	1564	11400	2333	18021	3773
10,0	3441	1394	26963	2930	29339	4535	56958
	3202	1321	25788	2994	29371	4579
20,0	8187	1744	35584	5553	40386	5583	57128
	7524	1497	35396	5576	38911	5744

Table 3: Equilibrium concentration in the solution (Ce) using 5 concentrations of test substance in GH, LR and LE soil (2 replicates)

Solution (ug / mL)	GH		Ce (ug /mL) LR		LE
	Ads	Des	Ads	Des	Ads	Des
0,5	0,023	0,006	0,079	0,013	0,128	0,027
1,0	0,050	0,011	0,146	0,026	0,253	0,057
5,0	0,258	0,088	0,954	0,100	1,575	0,198
10,0	0,583	0,162	4,631	0,002	5,154	0,375
20,0	2,750	0,240	12,425	0,538	13,881	0,860

Table 4: Total amount of test substance adsorbed and desorbed on GH, LR and LE soils (means of 2 replicates) using 5 concentrations of test substance.

Concentration Solution (ug / mL)	(ug / g)
	GH		LR		LE
	Ads.	Des.	Ads.	Des.	Ads.	Des.
0,5	2,38	0,03	2,10	0,06	1,86	0,13
1,0	4,75	0,06	4,27	0,13	3,74	0,29
5,0	23,71	0,44	20,23	0,50	17,13	0,99
10,0	47,08	0,81	26,85	0,01	24,23	1,87
20,0	86,25	1,20	37,88	2,69	30,60	4,30

Table 5: Freundlich isotherm equations and K values for GH, LR and LE soils

Equations				K (ug / g)	Koc	R2*
	GH soil
Adsorption	log x / m = log	53,43 + 0,784	log Ce	53,4	1094	97,0
Desorption	log x / m = log	257,4 + 0,909	log Ce	257,4		99,1
	LR soil
Adsorption	log x / m = log	11,89 + 0,558	log Ce	11,9	672	92,4
Desorption	log x / m = log	19,74 + 0,171	log Ce	19,7		85,3
	LE soil
Adsorption	log x / m = log	8,33 + 0,608	log Ce	8,3	678	94,2
Desorption	log x / m = log	42,55 + 0,846	log Ce	42,6		94,2
* Correlation coefficient

Table 6: Adsorption/Desorption classification of test substance according to MHM/SEMA, 1990

Ka values		Adsorption
0 - 5		low
> 5 - 15		medium
> 15 - 80		high
> 80		very high

Validity criteria fulfilled:

not specified

Conclusions:

The total amount of the test substance ferbam adsorbed on GH soil was about 93%. On LR soil was about 70%, and on LE soil 60%. The coefficients of adsorption and desorption from GH soil were 53.4 and 257.4, from LR soil were 11.9 and 19.7, and from LE soil these coefficients were 8.3 and 42.6, respectively.

Executive summary:

This study was conducted to determine the adsorption and desorption characteristics of ferbam on LE {Typic Hapludox), GH {Cumulic Humaquept) and LR (Rhodic Hapludox) soils.

The extent of adsorption of chemical onto sediment or soil is measured by equilibrating chemicals aqueous solutions with différents quantities of sediment or soil. After steady-state is reached, the distribution of chemical between the water phase and the solid phase is quantitatively measured by a suitable analytical method.

The following concentrations of active ingredient were used: 0.5, 1.0, 5.0, 10.0 and 20.0 ug of ferbam/mL and 0.01 uCi/mL of radioactivity. The assay was carried out with two replicates in centrifuge tubes containing 1.0g of soil and 5.0 mL of treating solutions, that were agitated and centrifuged. Aliquots of the supernatant were pipetted and analyzed using the Liquid Scintillation Analyzer to quantify the amount of test compound remaining in the solution. The amount of adsorbed product was then calculated. To quantify the desorbed product, the supernatant solution was completely drained, and 5.0 mL of 0.01M CaCl2 was added. The tubes were agitated, centrifuged, sampled and analyzed as above mentioned.

According to the results, the coefficients of adsorption from GH, LR and LE soils were 53.4, 11.9 and 8.3, respectively.

Description of key information

Test procedure was conducted in accordance with generally accepted scientific standards and described in sufficient detail. The extent of adsorption of chemical onto sediment or soil is measured by equilibrating chemicals aqueous solutions with differents quantities of sediment or soil. After steady-state is reached, the distribution of chemical between the water phase and the solid phase is quantitatively measured by a suitable analytical method.

The total amount of the test substance ferbam adsorbed on GH soil was about 93%. On LR soil was about 70%, and on LE soil 60%. The coefficients of adsorption and desorption from GH soil were 53.4 and 257.4, from LR soil were 11.9 and 19.7, and from LE soil these coefficients were 8.3 and 42.6, respectively.

Key value for chemical safety assessment

Koc at 20 °C:

1 094

Additional information

Key: da Silva, 1997

This study was conducted to determine the adsorption and desorption characteristics of ferbam on LE {Typic Hapludox), GH {Cumulic Humaquept) and LR (Rhodic Hapludox) soils.

The extent of adsorption of chemical onto sediment or soil is measured by equilibrating chemicals aqueous solutions with différents quantities of sediment or soil. After steady-state is reached, the distribution of chemical between the water phase and the solid phase is quantitatively measured by a suitable analytical method.

The following concentrations of active ingredient were used: 0.5, 1.0, 5.0, 10.0 and 20.0 ug of ferbam/mL and 0.01 uCi/mL of radioactivity. The assay was carried out with two replicates in centrifuge tubes containing 1.0g of soil and 5.0 mL of treating solutions, that were agitated and centrifuged. Aliquots of the supernatant were pipetted and analyzed using the Liquid Scintillation Analyzer to quantify the amount of test compound remaining in the solution. The amount of adsorbed product was then calculated. To quantify the desorbed product, the supernatant solution was completely drained, and 5.0 mL of 0.01M CaCl2 was added. The tubes were agitated, centrifuged, sampled and analyzed as above mentioned.

According to the results, the coefficients of adsorption from GH, LR and LE soils were 53.4, 11.9 and 8.3, respectively.

Supporting information: Warren, 1987

Aqueous solutions of 14C-Ferbam were equilibrated with four soil types and the adsorption coefficients and adsorptions constants were determined. Liquid scintillation counting analysis was employed to measure test material concentrations in the aqueous phase.

The results are summarized below:

Soil Type	% Organic Carbon	Adsorption		Desorption
		Kd	Koc	Kc	Koc
#1 Ahapulgus Sandy loam	0.826	3.57	432	20.40	2470
#2 Leon Sand	0.913	20.15	2207	98.87	10829
#3 Crittendon Silt Loam	1.30	14.9	1146	39.00	3000
#4 Clay Loam	2.43	22.9	942	53.26	2192