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Reference
Endpoint:
adsorption / desorption, other
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1991 (publication date)
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Version / remarks:
The sorption coefficients were determined according to the test sequence of the modified version of
the OECD-Guidcline 106 (von Oepen et al., 1989, 1990).

Oepen, B. von, Kördel, W., Klein, W. (1989), Soil Preparation for the estimation of adsorption coefficents (koc) of organic chemicals, Chemosphere 18, 1495-1511.
Oepen, B. von (1990), Sorption organischer Chemikalien an Böden, Dissertation, Universität Duisburg, Verlag Maraun.
Deviations:
not applicable
Principles of method if other than guideline:
Comparative study including 50 chemicals
GLP compliance:
no
Type of method:
batch equilibrium method
Media:
other: 2 soils, one sediment
Radiolabelling:
no
Analytical monitoring:
yes
Remarks:
Supernatant concentrations were determined by GC, HPLC or szintillation measurements as outlined in von Oepen (1990). Oepen, B. von (1990), Sorption organischer Chemikalien an Böden, Dissertation, Universität Duisburg, Verlag Maraun.
Details on sampling:
- Concentrations: 0.15, 0.5, 5, and 15 mg/L
- Sampling interval: 0.5, 1, 1.5, 5, 24, and 72 h
- Freundlich isotherm determined after 16 h (sorption eqiuilibrium)
Matrix no.:
#1
Matrix type:
Podzol
% Clay:
2.6
% Silt:
8.2
% Sand:
89.2
% Org. carbon:
4.85
pH:
2.8
CEC:
15.1 other: mval (100g)
Matrix no.:
#2
Matrix type:
Alfisol
% Clay:
15.9
% Silt:
14.4
% Sand:
69.7
% Org. carbon:
1.25
pH:
6.7
CEC:
12.3 other: mval (100g)
Matrix no.:
#3
Matrix type:
other: sediment lake Constance (sublimnic soil)
% Clay:
35.7
% Silt:
58.8
% Sand:
5.5
% Org. carbon:
1.58
pH:
7.1
CEC:
13.4 other: mval (100g)
Details on matrix:
Three types of soil examined:
Podsol (acidic forest soil, pH 2.8); Alfisol (a neutral agricultural soil, pH 6.7); sublimnic soil (sediment from Lake Constance, pH 7.1)
Details on test conditions:
Please see IUCLID section "Any other information on materials and methods incl. tables".
Sample No.:
#1
Duration:
16 h
Temp.:
>= 20 - <= 25 °C
Remarks:
Equilibration for 0.5, 1, 1.5, 5, 24, and 72 hours - sorption equilibrium was reached within 16 hours for all substances investigated.
Sample no.:
#1
Duration:
16 h
Temp.:
22.5 °C
Remarks:
Performed according to OECD 106 (temperature range 20 to 25 °C); supernatant concentrations were determined after 8 and 16 hours equilibration. Sorption was reversible to a great extent for all substances under study.
Sample No.:
#1
Type:
Koc
Remarks:
Podzol
Value:
36.4 L/kg
pH:
2.8
Temp.:
22.5 °C
Matrix:
Soil
% Org. carbon:
4.85
Remarks on result:
other: Calculated from Kd based on default for OC content given in R.16 guidance document
Sample No.:
#2
Type:
Koc
Remarks:
Alfisol
Value:
65.6 L/kg
pH:
6.7
Temp.:
22.5 °C
Matrix:
Soil
% Org. carbon:
1.25
Remarks on result:
other: Calculated from Kd based on default for OC content given in R.16 guidance document
Sample No.:
#3
Type:
Koc
Remarks:
LakeLake Constance sublimnic soil (sediment)
Value:
33.8 L/kg
pH:
7.1
Temp.:
22.5 °C
Matrix:
Sediment
% Org. carbon:
1.58
Remarks on result:
other: Calculated from Kd based on default for OC content given in R.16 guidance document
Key result
Type:
Koc
Value:
43.2 L/kg
Temp.:
22.5 °C
Matrix:
geometric mean value over all three matrices analyzed (2 soils, one sediment)
Remarks on result:
other: very similar (low) values for Koc in all three matrices analyzed justify derivation of a geometric mean value generally applicable in environmental risk assessment
Sample No.:
#1
Type:
Kd
Remarks:
Podzol
Value:
0.73 L/kg
pH:
2.8
Temp.:
22.5 °C
Matrix:
Soil
% Org. carbon:
4.85
Sample No.:
#2
Type:
Kd
Remarks:
Alfisol
Value:
1.31 L/kg
pH:
6.7
Temp.:
22.5 °C
Matrix:
Soil
% Org. carbon:
1.25
Sample No.:
#3
Type:
Kd
Remarks:
Lake Constance sublimnic soil
Value:
1.69
pH:
7.1
Temp.:
22.5 °C
Matrix:
Sediment
% Org. carbon:
1.58
Adsorption and desorption constants:
Please see IUCLID section "Any other information on results incl. tables" below.
Recovery of test material:
Please see IUCLID section "Any other information on results incl. tables" below.
Concentration of test substance at end of adsorption equilibration period:
Not reported
Concentration of test substance at end of desorption equilibration period:
Not reported
Transformation products:
not specified
Details on results (Batch equilibrium method):
Please see IUCLID section "Any other information on results incl. tables" below.
Statistics:
Not reported

For all test substances the sorption equilibrium was reached within 16 h.

Based on desorption kinetics (supernatant concentrations determined after 8 and 16 hours equilibration), adsorption was reversible to a great extent for all substances studied, i.e. including n-butylamine.

Performed mass balancing resulted in a recovery of > 80 % for all compounds assessed in the study.

Results for n-butylamine:

The table below summarizes results for n-butlyamine as given by von Oepen et al. (1991), i.e. resulting Kf, the corresponding correlation coefficient and slope of Freundlich-isotherm. Further, von Oepen reported Koc calcuated from Kd and OC content of each soil/sediment. Other data were added ex post, as outlined in the text below.

Soil type Kf % OC in soil Koc (according to von Oepen) Kd from Koc and %OC Koc from Kd based on default OC concentration according to ECHA guidance R.16 (2% for soil; 5% for sediment)  r 1/n
Podzol 0.73 4.85 15 0.728 36.375 1.00 0.98
Alfisol 1.32 1.25 105 1.313 65.625 1.00 0.96
Sediment 1.69 1.58 107 1.691 33.812 1.00 0.90

Kf was calculated based on 4 test item concentrations (15, 5, 0.5, and 0.15 mg/L). Kd was not reported by von Oepen et al. (1991). Based on the relationship Koc = Kd/(weight fraction OC), Kd was calculated ex post from Koc and the OC content of the respective soil / sediment. Because 1/n is approximately 1, Kf approximates Kd (according to the relationship Cs = Kf*Cw^(1/n); Kd = Cs/Cw; Cs and Cw being the concentration in solids and water, respectively, at equilibrium). It is well known and confirmed by the authors, that especially for species ionized under environmental conditions (which is the case for n-butylamine based on a pKa of 10.8) adsorption does not correlate with OC content and thus normalization of adsorption to the OC content is not meaningful. For environmental exposure estimation, adsorption to soil is estimated based on Koc and default assumptions for compartmental OC. For environmental RA it is therefore reasonable to either use only Kd-values or calculate Koc based on default OC content as given according to ECHA guidance R.16 for soil and sediment. This approach is e.g. proposed by Gustafon (1989). Accordingly, from Kd values indicative Koc-values were calculated based on defaults for OC content as given in R.16. These values are regarded to be of higher relevance than Koc values originally reported by von Oepen et al. (1991).

Gustafson, D.I. (1989)

Groundwater ubiquity score: A simple method for assessing pesticide leachability

Environmental Toxicology and Chemistry, 8, 339-357

Validity criteria fulfilled:
not applicable
Conclusions:
In a study performed according to a modified version of OECD 106 (batch equilibrium approach), the submission substance was determined to have a very low potential for adsorption in three very different media with regard to pH, organic carbon content, sand, silt and clay content.
Overall result: Koc (geometric mean over three matrices) = 43.2 L/kg
Executive summary:

The adsorption potential for n-butylamine and other compounds was determined in a study performed according to a modified version of OECD 106 (batch equilibrium approach; von Oepen et al., 1991).

For all test substances the sorption equilibrium was reached within 16 h.

Based on desorption kinetics (supernatant concentrations determined after 8 and 16 hours equilibration), adsorption was reversible to a great extent for all substances studied, i.e. including n-butylamine.

Performed mass balancing resulted in a recovery of > 80 % for all compounds assessed in the study.

The table below summarizes characteristics on soils used as well as results for n-butylamine as given by von Oepen et al. (1991), i.e. resulting Kf (calculated based on 4 test item concentrations), the slope of Freundlich-isotherm as well as calculated Koc (from Kd and OC content of each soil/sediment). Other data were added ex post:

Kd was not reported by von Oepen et al. (1991). Based on the relationship Koc = Kd/(weight fraction OC), Kd was calculated from Koc and the OC content of the respective soil / sediment.

Because 1/n is approximately 1, Kf approximates Kd (according to the relationship Cs = Kf*Cw^(1/n); Kd = Cs/Cw; Cs and Cw being the concentration in solids and water, respectively, at equilibrium).

It is well known and confirmed by the authors, that especially for substances ionized under environmental conditions (which is the case for n-butylamine based on a pKa of 10.8) adsorption does not correlate with OC content and thus normalization of adsorption to the OC content is not meaningful. For environmental exposure estimation under REACH, adsorption to solids is estimated based on Koc and default assumptions for compartmental OC. For environmental RA it is therefore reasonable to either use only Kd-values or calculate Koc based on default OC content as given according to ECHA guidance R.16 for soil and sediment. This approach is proposed e.g. by Gustafson (1989). Accordingly, from Kd values indicative Koc-values were calculated based on defaults for OC content as given in ECHA guidance document R.16. The resulting values are regarded to be of higher relevance than Koc values originally reported by von Oepen et al. (1991).

Soil type % OC in soil pH CEC [mval/100 g] Sand/Silt/Clay [%] Kf KOC (according to von Oepen) Kd from Koc and %OC Koc from Kd based on default OC concentration accordint to ECHA guidance R.16 (2% for soil; 5% for sediment)  1/n
Podzol 4.85 2.8 15.1 89.2/8.2/2.6 0.73 15 0.73 36.4 0.98
Alfisol 1.25 6.7 12.3 69.7/14.4/15.9 1.32 105 1.31 65.6 0.96
Sediment 1.58 7.1 13.4 5.5/58.8/35.7 1.69 107 1.69 33.8 0.90

Based on the very similar (low) values for Koc in all three matrices analysed it is justified to derive a geometric mean value of Koc over all three matrices, generally applicable in environmental risk assessment:

Koc (geometric mean over 2 soils and one sediment) = 43.2 L/kg.

Overall, according to these data the adsorption potential for n-Butylamine to the solids fraction of soils and sediment is very low.

Description of key information

In a study performed according to a modified version of OECD 106 (batch equilibrium approach) performed with n-butylamine and read-across for isopropylamine, a very low potential for adsorption was determined from three very different soils (2 soils, one sediment) with regard to pH, organic carbon content, sand, silt and clay content.

Overall result: Koc (geometric mean over three matrices) = 43.2 L/kg

Key value for chemical safety assessment

Koc at 20 °C:
43.2

Additional information

In the valid key study (publication) the adsorption potential for n-butylamine and other compounds (but not isopropylamine) was determined according to a modified version of OECD 106 (batch equilibrium approach; von Oepen et al., 1991). Data for n-butylamine were assessed to be appropriate as source data (without adaption) for read-across to the target substance isopropylamine (see read-across report in IUCLID section 13).

For all test substances including the source chemical n-butylamine, the sorption equilibrium was reached within 16 h.

Based on desorption kinetics (supernatant concentrations determined after 8 and 16 hours equilibration), adsorption was reversible to a great extent for all substances studied, i.e. including n-butylamine.

Performed mass balancing resulted in a recovery of > 80 % for all compounds assessed in the study.

The table below summarizes characteristics on soils used as well as results for n-butylamine as given by von Oepen et al. (1991), i.e. resulting Kf (calculated based on 4 test item concentrations), the slope of Freundlich-isotherm as well as calculated Koc (from Kd and OC content of each soil/sediment). Other data were added ex post:

Kd was not reported by von Oepen et al. (1991). Based on the relationship Koc = Kd/(weight fraction OC), Kd was calculated from Koc and the OC content of the respective soil / sediment.

Because 1/n is approximately 1, Kf approximates Kd (according to the relationship Cs = Kf*Cw^(1/n); Kd = Cs/Cw; Cs and Cw being the concentration in solids and water, respectively, at equilibrium).

It is well known and confirmed by the authors, that especially for substances ionized under environmental conditions (which is the case for n-butylamine based on a pKa of 10.8) adsorption does not correlate with OC content and thus normalization of adsorption to the OC content is not meaningful. For environmental exposure estimation under REACH, adsorption to solids is estimated based on Koc and default assumptions for compartmental OC. For environmental RA it is therefore reasonable to either use only Kd-values or calculate Koc based on default OC content as given according to ECHA guidance R.16 for soil and sediment. This approach is proposed e.g. by Gustafson (1989). Accordingly, from Kd values indicative Koc-values were calculated based on defaults for OC content as given in ECHA guidance document R.16. The resulting values are regarded to be of higher relevance than Koc values originally reported by von Oepen et al. (1991).

Soil type % OC in soil pH CEC [mval/100 g] Sand/Silt/Clay [%] Kf KOC (according to von Oepen) Kd from Koc and %OC Koc from Kd based on default OC concentration accordint to ECHA guidance R.16 (2% for soil; 5% for sediment)  1/n
Podzol 4.85 2.8 15.1 89.2/8.2/2.6 0.73 15 0.73 36.4 0.98
Alfisol 1.25 6.7 12.3 69.7/14.4/15.9 1.32 105 1.31 65.6 0.96
Sediment 1.58 7.1 13.4 5.5/58.8/35.7 1.69 107 1.69 33.8 0.90

Based on the very similar (low) values for Koc in all three matrices analysed it is justified to derive a geometric mean value of Koc over all three matrices, generally applicable in environmental risk assessment:

Koc (geometric mean over 2 soils and one sediment) = 43.2 L/kg.

Overall, according to these data the adsorption potential for the source chemical n-Butylamine to the solids fraction of soils and sediment is very low. This result is directly applicable to the target substance isopropylamine (see read-across report in IUCLID section 13).

Reference:

Gustafson, D.I. (1989)

Groundwater ubiquity score: A simple method for assessing pesticide leachability

Environmental Toxicology and Chemistry, 8, 339-357