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Administrative data

Endpoint:
adsorption / desorption
Remarks:
adsorption/desorption
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP, guideline study
Cross-referenceopen allclose all
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: OECD 106 (screening version): (Screening version): "Adsorption/Desorption, adopted May 12, 1981.
Deviations:
no
Remarks:
Not specified in report
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes
Type of method:
batch equilibrium method
Media:
soil

Test material

Constituent 1
Reference substance name:
-
EC Number:
405-430-6
EC Name:
-
Cas Number:
65143-89-7
Molecular formula:
UVCB
IUPAC Name:
2-hexadecyl-4-(2-sulfophenoxy)benzene-1-sulfonic acid 2-hexadecyl-4-(4-sulfophenoxy)benzene-1-sulfonic acid 2-hexadecyl-5-(2-hexadecylphenoxy)benzene-1-sulfonic acid 3-hexadecyl-5-(3-hexadecyl-4-sulfophenoxy)benzene-1-sulfonic acid hexasodium hydride
Details on test material:
DOWFAX 8390-D
Reference: Batch 9401205-50A
Composition: Active ingredient minimal 92%
Appearance: Tan powder
Description: Hexadecyl (sulfophenoxy) benzenesulfonic acid disodium salt + Hexadecyl (hexadecylsulfophenoxy) benzene- sulfonic acid disodium salt
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No data
Radiolabelling:
no

Study design

Test temperature:
20C

HPLC method

Details on study design: HPLC method:
Not applicable



Batch equilibrium or other method

Analytical monitoring:
yes
Details on sampling:
All soil samples were sieved (2 mm size, Emergo B.V., Landsmeer, The Netherlands) and air dried.
Solvent: 0.01 M Calcium Chloride (p.a. Merck, Darmstadt, Germany) in double distilled water.
Each soil was recognized by the international guideline (OECD).

Sample pretreatment
Samples of the supernatant of approximately 10 ml were taken and centrifuged for 5 minutes at 3500 g and 20°C. Each resultant clear supernatant was analysed without further pretreatment.
Details on matrix:
TEST SYSTEM AND RATIONALE
For the study, three different soils differing in pH, clay-content, organic matter content and thus in cation exchange capacity were used:
( classification accordi.ng to NEN 5104, 1989)
Soil I : strong silty sand (Wageningen, The Netherlands)
Soil II : strong sandy loam (Kloosterburen, The Netherlands)
Soil III : weak sandy clay (Fann (near Luzern), Switzerland)

Parameter Soil I Soil II Soil III
Horizon 0-30 cm 0-30 cm 0-20 cm
Clay (<2 um) 6.0% 13.6% 17.8%
Silt (2-50um) 11.1% 39.8% 28.6%
Sand (50-2000 um) 81.3% 41.7% 53.6%
Dry weight content 99.6% 99.9% 98.7%
Organic bound carbon 1.4% 1.8% 1.35%
Carbonate as CaC03 0.2% 3.1% 0.2%
pH 4.0 7.5 6.0
Cation exchange
capacity (meqI100 g) 4.7 10.9 13.2
Extractable cations
(meqI100 g):
Ca 1.33 9.06 8.0
Mg 0.17 1.00 1.1
Na <0.01 0.15 0.1
K 0.23 0.96 0.2
H 5.5 0.6 4.9

All soil samples were sieved (2 mm size, Emergo B.V., Landsmeer, The Netherlands) and air dried.
Solvent: 0.01 M Calcium Chloride (p.a. Merck, Darmstadt, Germany) in double distilled water.
Each soil was recognized by the international guideline (OECD).
Details on test conditions:

VALIDATION OF THE TEST PROCEDURE
The test method as outlined in this report is validated periodially , using 2,4-dichlorophenoxyacetic acid. The results are in accordance with
the NOTOX criteria of the validation.

PERFORMANCE OF THE TEST
Test solution preparation
A 94.4 E-3 g / l solution of DOWFAX 8390-D in 0.01 M CaCl2 was prepared.

Soil equilibration
Prior to the adsorption test, the soils I, II and III were equilibrated with twice their weight of water before use. Therefore, an amount of 2 g
of each soil was weighed into each of three 20 ml glass vials . To each vial , an accurately weighed amount of 4 ml double distilled water was
added. The vials were securely closed and gently tumbled for 76.5 hours at room temperature. Thereafter, the vials were centrifuged for
5 minutes at 170 g and 20°C and most o f the supernatants were removed (and weighed) .

Adsorption screeninq test
For soil I, II and III, an accurately weighed amount of 10 ml of the test solution was added to two of the equilibrated soil samples. An accurately
weighed amount of 10 ml 0.01 M CaCl2 was added to the third equilibrated soil sample. An additional blank test was performed without soil , using
10 ml of the test solution.
All vials were gently tumbled for 16 hours at room temperature. Subsequently, the vials were centrifuged for 5 minutes at 170 g and 20°C.
The supernatants were pipetted off as much as possible and weighed. The supernatant of the blank without soil was not weighed.

Desorption screeninq test
The amount of adsorption to soil I, II and III was > 25%. Therefore, the screening test desorption was performed for each o f the soil samples from
the adsorption test. To each soil, 10 ml 0.01 M CaC12 was added. The vials were securely closed and gently tumbled for 16 hours at room temperature. Subsequently, the vials were centrifuged for 5 minutes at 170 g and 20°C and each supernatant was pipetted off . The above mentioned procedure was repeated once, using a fresh CaCl2 solution.
Duration of adsorption equilibrationopen allclose all
Sample No.:
#1
Duration:
16 h
Initial conc. measured:
932.6 other: ug
Temp.:
20 °C
Sample No.:
#2
Duration:
16 h
Initial conc. measured:
930.99 other: ug
Temp.:
20 °C
Sample No.:
#3
Duration:
16 h
Initial conc. measured:
933.86 other: ug
Temp.:
20 °C
Sample No.:
#4
Duration:
16 h
Initial conc. measured:
933.84 other: ug
Temp.:
20 °C
Sample No.:
#5
Duration:
16 h
Initial conc. measured:
932.35 other: ug
Temp.:
20 °C
Sample No.:
#6
Duration:
16 h
Initial conc. measured:
942.41 other: ug
Temp.:
20 °C
Duration of desorption equilibrationopen allclose all
Sample no.:
#1
Duration:
16 h
Conc. of adsorbed test mat.:
98.9 other: %
Temp.:
20 °C
Sample no.:
#2
Duration:
16 h
Conc. of adsorbed test mat.:
99.14 other: %
Temp.:
20 °C
Sample no.:
#3
Duration:
16 h
Conc. of adsorbed test mat.:
99.53 other: %
Temp.:
20 °C
Sample no.:
#4
Duration:
16 h
Conc. of adsorbed test mat.:
99.48 other: %
Temp.:
20 °C
Sample no.:
#5
Duration:
16 h
Conc. of adsorbed test mat.:
99.17 other: %
Temp.:
20 °C
Sample no.:
#6
Duration:
16 h
Conc. of adsorbed test mat.:
99.22 other: %
Temp.:
20 °C
Computational methods:
Adsorption screeninq test :
The percentage o f the test substance adsorbed was calculated as:
A=100 x (G - (Ce x V0)/G = 100x(X/G)
The adsorption coefficient for the determination was calculated as:

K' = (X/M)/Ce

The adsorption coefficient was also calculated as a function of the organic carbon content of the soil :
K'oc = (K'/ % organic carbon) x 100

Desorption screening test :
The percentage of the adsorbed test substance which was desorbed was calculated as:
D = 100 x (( C1 + C2) x V - (V0 - V) x Ce) / X


The percentage of the adsorbed test substance which was not desorbed was calculated as:
R = 100 x (G - (Ce + C 1 + C2) x V) / X

where:
G= quantity of material employed (ug)
Ce= concentration of test substance remaining in the solution after adsorption (ug/ml)
V0= original volume of solution employed (ml)
M= dry weight of soil employed (g)
C1= concentration of test substance in the solution after the first wash (ug/ml)
C2= concentration of test substance in the solution after the second wash (ug/ml)
V= volume of solution obtained after the adsorption step (ml)
X= amount of test substance adsorbed (ug)

Results and discussion

Adsorption coefficientopen allclose all
Type:
Koc
Value:
>= 34 900 - <= 64 300
Type:
log Koc
Value:
>= 4.54 - <= 4.81

Results: HPLC method

Details on results (HPLC method):
Not applicable

Results: Batch equilibrium or other method

Adsorption and desorption constants:
Not determined
Recovery of test material:
Not determined
Concentration of test substance at end of adsorption equilibration period:
3.95E-1 to 9.63E-1
Concentration of test substance at end of desorption equilibration period:
2.76E-1 to 6.89E-1
Transformation products:
not specified
Details on results (Batch equilibrium method):
In the HPLC chromatograms of DOWFAX 8390-D, one large peak at 9.4 minutes and several smaller peaks were observed. The large peak derived from the main component whereas the smaller peaks derived from minor components. The peak at 7.4 minutes was the greatest minor component.
The chromatograms of the blank soils ( test substance omitted) did not show any peak with the same retention as the test substance.

The amount of test substance recovered from the blank without soil was 101%. Because this value was considered to fall within the reproducibility
of the method of chemical analysis, no correction-factor was applied on the quantity of material employed (G).

The concentration in some of the pretreated samples from the desorption test was below the limit of detection (0.276E-3 g/l) .
The individual measurements of the main component of each soil sample from both the adsorption and desorption (screening) test are summarized i n Table 1.
Table 1 Individual measurements of the main component of the adsorption/desorption screening test of DOWFAX 8390-D at room temperature.
........................................................................
IA IB IIA IIB IIIA IIIB
G [ug] 932.60 930.99 933.86 933.84 932.35 942.41
Ce [ug/ml] 9.63e-01 7.51e-01 3.95e-01 4.39e-01 6.87e-01 6.48e-01
VO [ ml ] 10.63 10.64 11.16 11.16 11.23 11.35
M [g] 1.962 2.028 2.034 1.984 2.008 2.048
A [%] 98.90 99.14 99.53 99.48 99.17 99.22
K ' 4.88e+02 6.09e+02 1.16e+03 1.07e+03 6.71e+02 7.05e+02
K'oc 3.49e+04 4.35e+04 6.43e+04 5.93e+04 4.97e+04 5.22e+04
v [ml] 9.83 9.80 9.86 9.83 9.65 9.77
C 1 [ug/ml] 6.59e-01 5.86e-01 2.76e-01 2.76e-01 4.57e-01 4.25e-01
C2 [ug/ml] 6.89e-01 5.29e-01 2.76e-01 2.76e-01 4.71e-01 4.18e-01
D [%] 1.35 1.12 0.53 0.52 0.85 0.77
R [%] 98.65 98.88 99.47 99.48 99.15 99.23


G = Quantity of material employed (ug)
Ce = Concentration of test substance remaining in the solution after adsorption (ug/ml)
Vo = Original volume of solution employed (ml)
M = Dry weight of soil employed (g)
A = Adsorption (%)
K ' = Adsorption coefficient
K'oc = K ' as function of organic carbon content .
V = Volume of solution obtained after the adsorption step (ml)
C1= Concentration of test substance in the solution after the first wash (ug/ml)
C2 = Concentration of test substance in the solution after the second wash (ug/ml)
D = Desorption (%)
R = Not desorbed (%)

The average values of A, D, R, K' and K'oc of the main component are shown in Table 2.
Table 2 Results of the adsorption/desorption (screening) test of the main-component of DOWFAX 83904 at room temperature.

Soil I Soil II Soil III
A [% ] 99.0 99.5 99.2
D [%] 1.2 0.5 0.8
R [%] 98.8 99.5 99.2
K' 548 1112 688
K'oc 392 E2 618 E2 509 E2
Statistics:
No data

Any other information on results incl. tables

None

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
The results can be summarized as follows: The test material DOWFAX* 8390-D surfactant attained 99.0, 99.5 and 99.2 % adsorption to soil I, II and Ill, respectively; the corresponding desorption values have been determined to be 1.2, 0.5 and 0.8 %. These data correpond to the K'oc values (adsorption coefficients as a function of the organic carbon content of the soils) of 392E2 , 618E2 and 509E2 for soil type I, II and Ill, respectively.
Executive summary:

DOWFAX* 8390-D surfactant is the dry form of a diphenyloxide based anionic surfactant which consists of disodium di- and monohexadecyldiphenyloxide disulfonate. The material was assayed for soil adsorption/desorption using a screening test according to OECD Guideline Number 106 (adopted May 12, 1981).

For the investigation of the adsorption behaviour three different soils were used: strong silty sand (pH 4.0, 6.0 % clay, 1.4 % organic matter), strong sandy loam (pH 7.5, 13.6 % clay, 1.8 % organic matter) and weak sandy clay (pH 6.0, 17.8 % clay, 1.35 % organic matter). The soils were first equilibrated with water. To 2 g of each equilibrated soil 10 ml of an aqueous solution of the test material (94.4 mg/l in 0.01 M CaCl2) was added. The following two controls were included: CaCl2, solution without test compound and test solution without soil. Incubation took place at room temperature with gentle tumbling over a period of 16 hours. Subsequently, the

vials were centrifuged (5 min., 170 x g) and the supernatants pipetted off. The amount of residual test material still present in the supernatant after incubation (adsorption test) was analyzed with the help of High Performance Liquid, Chromatography (HPLC). To follow the desorption of the test material 10 ml of 0.01 M CaCl2, solution was added to the treated soil samples. The vials were again tumbled for 16 hours at room temperature followed by centrifugation (5 min., 170 x g) and HPLC analysis of the supernatants.

The results can be summarized as follows: The test material DOWFAX* 8390-D surfactant attained 99.0, 99.5 and 99.2 % adsorption to soil I, II and Ill, respectively; the corresponding desorption values have been determined to be 1.2, 0.5 and 0.8 %. These data correpond to the K'oc values (adsorption coefficients as a function of the organic carbon content of the soils) of 392E2 , 618E2 and 509E2 for soil type I, II and Ill, respectively.

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