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Environmental fate & pathways

Adsorption / desorption

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Administrative data

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: 1b. Comparable to guideline study.

Data source

Reference
Reference Type:
publication
Title:
Sorption of Nonpolar and Polar Compounds to Soils: Processes, Measurements and Experience with the Applicability of the Modified OECD-Guideline 106
Author:
Von Oepen B., Koerdel W. and Klein W.
Year:
1991
Bibliographic source:
Chemosphere, Vol. 22, Nos 3-4, pp. 285- 3()4. 1991

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Version / remarks:
Older version
Principles of method if other than guideline:
Use of two soils and one sediment instead of five type of soils recommended in the present guideline.
GLP compliance:
no
Type of method:
other: Soil-Column Chromatography & Batch Equilibrium Studies
Media:
other: Two soils and one sediment

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
No further details
Radiolabelling:
no

Study design

Test temperature:
Not specified, but all samples were tested under the same conditions.

HPLC method

Details on study design: HPLC method:
See below.

Batch equilibrium or other method

Analytical monitoring:
yes
Details on sampling:
The soil samples were shaken for 0.5, 1, 1.5, 5, 24 respectively 72 hours. Then an aliquot of 1 ml of the water-phase was removed to determine the
concentration of the substance in the aqueous phase.
Details on matrix:
Soil Corg (%) pH [CaCl2] CEC mval CaCO3 (%) Sand (%) Silt (%) Clay (%)
100 g
Podzol 4.85 2.8 15.1 - 89.2 8.2 2.6
Alfisol 1.25 6.7 12.3 0.4 69.7 14.4 15.9
Sediment 1.58 7.1 13.4 38.9 5.5 58.8 35.7
Details on test conditions:
The sorption coefficients were determined according to the test sequence of the modified version of the OECD-Guidcline 106. The steps of the test-scquence were completely performed without considering the criteria for stopping the test-sequence.
Sorption coefficients independent of the concentration are obtained by fitting the Freundlich equation (Kf):
x/m
Kf = _______
C.e^1/n

kt = Freundlich adsorption constant
1/n = compound dependent constant

Results and discussion

Adsorption coefficientopen allclose all
Type:
Koc
Value:
460
% Org. carbon:
4.85
Remarks on result:
other: Soil type: Podzol; no data on test temperature.
Type:
other: Kf
Value:
22.29
% Org. carbon:
4.85
Remarks on result:
other: Soil type: Podzol; no data on test temperature.
Type:
Koc
Value:
47
% Org. carbon:
1.25
Remarks on result:
other: Soil type: Alfisol; no data on test temperature
Type:
other: Kf
Value:
0.59
% Org. carbon:
1.25
Remarks on result:
other: Soil type: Alfisol; no data on test temperature
Type:
Koc
Value:
71
% Org. carbon:
1.58
Remarks on result:
other: Soil type: Sediment; no data on test temperature
Type:
other: Kf
Value:
1.12
% Org. carbon:
1.58
Remarks on result:
other: Soil type: Sediment; no data on test temperature

Any other information on results incl. tables

Results show that the variation in Kf-values for thc diffcrcnt sorbents is up to two orders of magnitude for acids, one order of magnitude for esters and amides and up to a factor of 20 for the amines. All correlation coefficients obtained were highly significant (about 1). The slopes of the regression equations varied between 0.6 and 1.2.

Table 1: Comparison of the sorption coefficients of N-methylaniline with those of aniline and N,N-Dimethylaniline:

Soil

Kf

Koc

r

1/n

N-methylaniline:

Podzol

22.29

460

1.00

0.89

Alfisol

0.59

47

1.00

0.78

Sediment

1.12

71

0.99

0.77

aniline:

Podzol

6.34

131

1.00

0.76

Alfisol

1.39

111

1.00

0.72

Sediment

1.78

113

1.00

0.65

N,N-dimethylaniline:

Podzol

16.33

337

1.00

0.96

Alfisol

1.21

97

0.99

0.60

Sediment

1.84

116

1.00

0.91

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Conclusions:
Aromatic amines mainly sorb to the organic matter of the soil. The sorption of amino-groups to clay-minerals or pH-dependent sorption of acids plays a key role. A normalization to the organic matter of the soil does not significantly reduce the variation in polar substances' sorption coefficients. For polar compounds like the amines, the calculation of a koc-value is of no use. The variation of the sorption behaviour of a polar substance between two soils impedes the applicability to other soils.