Registration Dossier
Registration Dossier
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EC number: 931-335-9 | CAS number: 90622-74-5
Adsorption / desorption
Administrative data
Link to relevant study record(s)
- Endpoint:
- adsorption / desorption: screening
- Type of information:
- (Q)SAR
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
- Justification for type of information:
- QSAR prediction from a well-known and acknowledged tool. See below under ''attached background material section' for methodology and QPRF.
- Qualifier:
- according to guideline
- Guideline:
- other: REACH guidance on QSARs: Chapter R.6. QSARs and grouping of chemicals
- Principles of method if other than guideline:
- The Koc of the test substance was calculated using the MCI (Molecular Connectivity Index) and Kow based approaches of the KOCWIN v 2.01 program (EPISuite v 4.11). Since the test substance is an UVCB, the Koc values were estimated for individual constituents using SMILES codes as the input parameter.
- Computational methods:
- The Koc of the test substance was calculated using the MCI (Molecular Connectivity Index) and Kow based approaches of the KOCWIN v 2.01 program (EPISuite v 4.11). Since the test substance is an UVCB, the Koc values were estimated for individual constituents using SMILES codes as the input parameter.
- Key result
- Phase system:
- other: Estimated
- Value:
- 260.8 L/kg
- Remarks on result:
- other: MCI based method (log Koc: 1 to 3.16)
- Key result
- Phase system:
- other: Estimated
- Value:
- 279.21 L/kg
- Remarks on result:
- other: Kow based method (log Koc: 0.56 to 3.28)
- Validity criteria fulfilled:
- not applicable
- Conclusions:
- The weighted average Koc of test substance was estimated using the KOCWIN v 2.01 program (EPISuite v 4.11) to be 260.80 L/kg (log Koc=2.41) with the MCI method and 279.21 L/kg (log koc=2.44) with the Log Kow method.
- Executive summary:
The soil adsorption and desorption potential (Koc) of the test substance, C12-18 and C18-unsatd. DEA, was estimated using both the Molecular Connectivity Index (MCI) and the Log Kow methods of the KOCWIN v 2.01 program (EPISuite v 4.11). Since the test substance is an UVCB, the Koc values were estimated for individual constituents using SMILES codes as the input parameter. The predicted Koc values for all the constituents ranged from 10 to 1448 L/kg (MCI) and 3.66 to 1904 (log Kow) L/kg, respectively. The corresponding log Koc values ranged from 1 to 3.16 (MCI) and 0.56 to 3.28 (Kow) (US EPA, 2019). Given that the constituents are structurally very similar and vary only in the carbon chain length, a weighted average value, which considers the percentage of each constituent in the substance, was calculated to dampen the errors in predictions. The weighted average Koc values were calculated as 260.80 L/kg (log Koc = 2.41) and 279.21 L/kg (log Koc = 2.44), using the MCI and log Kow methods, respectively. Based on the above information, the test substance is expected to have a moderate adsorption potential (US EPA, 2012) to soil and sediment, leading to slow migration to groundwater. Overall, the Koc predictions for the test substance using KOCWIN model of EPI Suite TM can be considered ‘reliable with moderate confidence as not all constituents met the MW and structural fragment molecular descriptor domain criteria as defined in the KOCWIN v 2.01 user guide of EPI Suite TM.
- Endpoint:
- adsorption / desorption, other
- Remarks:
- adsorption/desorption kinetics and adsorption/desorption isotherms
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- supporting study
- Reliability:
- 1 (reliable without restriction)
- Justification for type of information:
- Refer to the section 13 for details on the category justification.
- Reason / purpose for cross-reference:
- read-across source
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
- Version / remarks:
- indirect test
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Type of method:
- batch equilibrium method
- Media:
- soil
- Test temperature:
- All tests were performed at 20°C ± 2°C in a temperature controlled room in the dark.
- Analytical monitoring:
- yes
- Remarks:
- Quantification of the N,N-bis(2-hydroxyethyl)dodecanamide was performed by means of liquid chromatography tandem mass spectrometry (LC-MS/MS).
- Details on sampling:
- 1. Concentrations
Preliminary studies: for the determination of adsorption kinetics and the desorption kinetics a test substance concentration of approx. 400 µg/L was used.
Main test (adsorption isotherm): final nominal target concentrations of the test substance were 55, 274, 548, 2740 and 5479 µg/L (soils IME 03-G, IME 04-A and LUFA 6S), 8, 55, 120, 274 and 548 µg/L (soil IME 02-A) and 8, 60, 120, 300 and 600 µg/L (soil IME 01-A).
2. Adsorption experiments
Adsorption kinetics: For each sample 1 g of sterilized soil was weighed into centrifuge tubes (80 mL) with ground glass stoppers. 14 samples, seven duplicate sample sets, were prepared for each soil. After addition of 45 mL sterilized 0.01 M CaCl2-solution the samples were placed on a horizontal shaker and preequilibrated for approx. 16h (overnight). Then 5 mL of the respective 10fold concentrated sterilized spiking solution (test substance dissolved in 0.01 M CaCl2-solution and sterilized by filtration through a 0.2 µm filter) was added to six duplicate sample sets. The seventh duplicate sample set was incubated as not applied blank. The samples were placed on a horizontal shaker. After agitation times of 2h, 4h, 8h, 16h, 24h and 48h a duplicate of samples was centrifuged at 3000 rpm for 5 min and the aqueous layer were sampled.
Adsorption isotherms: For each sample 2 g of sterilized soil was weighed into centrifuge tubes (250 mL) with ground glass and sterilized. 10 samples, 5 duplicate sample sets, were prepared for each soil. After addition of 90 mL 0.01 M CaCl2-solution the samples were sterilized. After sterilization the amount of 0.01 M CaCl2-solution was readjusted if necessary and the samples were placed on a horizontal shaker and preequilibrated for approx. 22h (overnight). Then 10 mL10fold concentrated spiking solution (test substance dissolved in 0.01 M CaCl2-solution and sterilized by filtration through a 0.2 µm filter) was added to the sample sets. The samples were placed on a horizontal shaker and were shaken for 23-24 h (the agitation times were differing a little depending on the particular samples sets). After completion of agitation the samples were centrifuged and aqueous supernatant and soil were separated.
3. Desorption experiments
Desorption kinetics: For each sample 1 g of sterilized soil was weighed into centrifuge tubes (80 mL) with ground glass stoppers. 14 samples, seven duplicate sample sets, were prepared for each soil. After addition of 45 mL 0.01 M CaCl2-solution the samples were sterilized. After sterilization the amount of 0.01 M CaCl2-solution was readjusted if necessary and the samples were placed on a horizontal shaker and preequilibrated for approx. 24 h (overnight). Then 5 mL of the respective 10fold concentrated sterilized spiking solution (test substance dissolved in 0.01 M CaCl2-solution and sterilized by filtration through a 0.2 µm filter) was added to six duplicate sample sets. The seventh duplicate sample set was incubated as not applied blank. The samples were placed on a horizontal shaker. After agitation time approx. 23 – 30 h (overnight; The preequilibration time was depending on the sampling time point in the subsequent desorption kinetic.) the samples were centrifuged and the aqueous supernatant removed and replaced by an equal volume of 0.01 M CaCl2 solution. The soil in the samples was suspended and the samples agitated again for 2h, 4h, 8h, 16h, 24h and 48h. At sampling intervals a duplicate of samples was centrifuged and aqueous supernatant and soil were separated.
Desorption isotherms: The desorption isotherm experiment was performed subsequent to the adsorption isotherm experiment as described in section 4.7.2. After the adsorption isotherm experiment the remaining supernatant was removed and replaced by an equal volume of sterilized 0.01 M CaCl2 solution. Samples were agitated again for 24 h. After the agitation the samples were centrifuged and aqueous supernatant and soil were separated. - Matrix no.:
- #1
- Matrix type:
- sandy loam
- % Clay:
- 3.4
- % Silt:
- 26.1
- % Sand:
- 70.5
- % Org. carbon:
- 0.95
- pH:
- 5.38
- CEC:
- 40 other: mmol/kg
- Matrix no.:
- #2
- Matrix type:
- silt loam
- % Clay:
- 16
- % Silt:
- 78.2
- % Sand:
- 5.7
- % Org. carbon:
- 1.06
- pH:
- 6.54
- CEC:
- 118 other: mmol/kg
- Matrix no.:
- #3
- Matrix type:
- silt loam
- % Clay:
- 23.9
- % Silt:
- 60.6
- % Sand:
- 15.5
- % Org. carbon:
- 4.45
- pH:
- 5.71
- CEC:
- 177 other: mmol/kg
- Matrix no.:
- #4
- Matrix type:
- loamy sand
- % Clay:
- 6.5
- % Silt:
- 12.2
- % Sand:
- 81.2
- % Org. carbon:
- 2.89
- pH:
- 5.15
- CEC:
- 102 other: mmol/kg
- Matrix no.:
- #5
- Matrix type:
- clay loam
- % Clay:
- 40.8
- % Silt:
- 34
- % Sand:
- 25.2
- % Org. carbon:
- 1.7
- pH:
- 7.3
- CEC:
- 232 other: mmol/kg
- Details on matrix:
- The Adsorption/Desorption of N,N-bis(2-hydroxyethyl)dodecanamide was performed with five top soils (IME 01-A, IME 02-A IME 03-G, IME 04-A and LUFA 6S). The soils were covering a wide range of properties especially with respect to clay content (soil texture), organic carbon content and pH value.
After air-drying the remaining moisture content of the soils was determined by drying soil samples in an oven at 105°C until a constant weight was reached. Soil parameters (particle size distribution, water holding capacity, pH, organic carbon content, cation exchange capacity) were determined under GLP conditions for the actual soil batches at Fraunhofer IME (soils IME 01-A, IME 02-A IME 03-G and IME 04-A) or LUFA Speyer (soil LUFA 6S). - Details on test conditions:
- Test conditions and sample treatment
All tests were performed at 20°C ± 2°C in a temperature controlled room in the dark. 0.01 M CaCl2 solution was stored in brown glass flasks until sample preparation. The experiments were conducted in sterilized samples. The soils and the 0.01 M CaCl2 solution were either sterilized separately (preliminary soil:solution ratio finding and kinetic experiments) or sterilized as complete samples, after sample preparation (main test isotherms).
Known volumes (5 mL or 10 mL) of solutions of N,N-bis(2-hydroxyethyl)dodecanamide in 0.01 M CaCl2 at known concentrations were added to sterilized soil samples of known dry weight which have been preequilibrated overnight in sterilized (45 mL or 90 mL) 0.01 M CaCl2. The mixtures were agitated for an appropriate time. The soil suspensions were separated by centrifugation at 3000 rpm for 5 min (50 mL samples) or at 2000 rpm for 5 min (100 mL samples). The aqueous supernatant was analyzed by LC-MS/MS for remaining test substance. The amount of the test substance adsorbed to soil was calculated as the difference between the amount of the test substance initially present in solution and the amount remaining at the end of the experiment (indirect method). - Sample No.:
- #1
- Duration:
- 22 h
- pH:
- 7.3
- Temp.:
- 20 °C
- Remarks:
- adsorption isotherms-Soil IME-01A
- Sample No.:
- #2
- Duration:
- 22 h
- pH:
- 6.54
- Temp.:
- 20 °C
- Remarks:
- adsorption isotherms-Soil IME-02A
- Sample No.:
- #3
- Duration:
- 22 h
- pH:
- 5.71
- Temp.:
- 20 °C
- Remarks:
- adsorption isotherms-Soil IME-02A
- Sample No.:
- #4
- Duration:
- 22 h
- pH:
- 5.15
- Temp.:
- 20 °C
- Remarks:
- adsorption isotherms-Soil IME-04A
- Sample No.:
- #5
- Duration:
- 22 h
- pH:
- 7.3
- Temp.:
- 20 °C
- Remarks:
- adsorption isotherms-Soil LUFA 6S
- Sample No.:
- #1
- Duration:
- 16 h
- pH:
- 5.38
- Temp.:
- 20 °C
- Remarks:
- adsorption kinetics-Soil IME-01A
- Sample No.:
- #2
- Duration:
- 16 h
- pH:
- 6.54
- Temp.:
- 20 °C
- Remarks:
- adsorption kinetics-Soil IME-02A
- Sample No.:
- #3
- Duration:
- 16 h
- pH:
- 5.71
- Temp.:
- 20 °C
- Remarks:
- adsorption kinetics-Soil IME-03G
- Sample No.:
- #4
- Duration:
- 16 h
- pH:
- 5.15
- Temp.:
- 20 °C
- Remarks:
- adsorption kinetics-Soil IME-04A
- Sample No.:
- #5
- Duration:
- 16 h
- pH:
- 7.3
- Temp.:
- 20 °C
- Remarks:
- adsorption kinetics-Soil LUFA 6S
- Sample no.:
- #1
- Duration:
- 24 h
- pH:
- 5.38
- Temp.:
- 20 °C
- Remarks:
- desorption kinetics-Soil IME-01A
- Sample no.:
- #2
- Duration:
- 24 h
- pH:
- 6.54
- Temp.:
- 20 °C
- Remarks:
- desorption kinetics-Soil IME-02A
- Sample no.:
- #3
- Duration:
- 24 h
- pH:
- 5.71
- Temp.:
- 20 °C
- Remarks:
- desorption kinetics-Soil IME-03G
- Sample no.:
- #4
- Duration:
- 24 h
- pH:
- 5.15
- Temp.:
- 20 °C
- Remarks:
- desorption kinetics-Soil IME-04A
- Sample no.:
- #5
- Duration:
- 24 h
- pH:
- 7.3
- Temp.:
- 20 °C
- Remarks:
- desorption kinetics-Soil LUFA 6S
- Computational methods:
- Sorption tests with different concentrations of the test substance were evaluated using the Freundlich equation:
logC_S^ads (eq)=K_F^ads+1⁄n×logC_aq^ads (eq)
Caqads(eq) = concentration of N,N-bis(2-hydroxyethyl)dodecanamide in solution (µg/mL) at equilibrium
Csads(eq) = concentration of N,N-bis(2-hydroxyethyl)dodecanamide in soil (µg/g) at equilibrium
1/n = exponential constant or slope
KFads= coefficient of adsorption - Key result
- Sample No.:
- #1
- Type:
- Koc
- Value:
- 386 dimensionless
- pH:
- 5.38
- Temp.:
- 20 °C
- Matrix:
- IME-01A
- % Org. carbon:
- 0.95
- Key result
- Sample No.:
- #2
- Type:
- Koc
- Value:
- 1 085 dimensionless
- pH:
- 6.54
- Temp.:
- 20 °C
- Matrix:
- IME-02A
- % Org. carbon:
- 1.06
- Key result
- Sample No.:
- #3
- Type:
- Koc
- Value:
- 828 dimensionless
- pH:
- 5.71
- Temp.:
- 20 °C
- Matrix:
- IME-03G
- % Org. carbon:
- 4.45
- Key result
- Sample No.:
- #4
- Type:
- Koc
- Value:
- 1 127 dimensionless
- pH:
- 5.15
- Temp.:
- 20 °C
- Matrix:
- IME-04A
- % Org. carbon:
- 2.89
- Key result
- Sample No.:
- #5
- Type:
- Koc
- Value:
- 995 dimensionless
- pH:
- 7.3
- Temp.:
- 20 °C
- Matrix:
- LUFA 6S
- % Org. carbon:
- 1.7
- Adsorption and desorption constants:
- The results of adsorption and desorption tests were summarised in Tables 1 and 2 in the section "Any other information on results incl. tables".
- Recovery of test material:
- See section "Any other information on results incl. tables".
- Sample no.:
- #1
- Duration:
- 48 h
- % Adsorption:
- 94.2
- Remarks on result:
- other: IME-01A(1). vol 50 mL
- Sample no.:
- #2
- Duration:
- 48 h
- % Adsorption:
- 92.6
- Remarks on result:
- other: IME-01A(2). vol 50 mL
- Sample no.:
- #3
- Duration:
- 48 h
- % Adsorption:
- 87
- Remarks on result:
- other: IME-02A(2). vol 50 mL
- Sample no.:
- #4
- Duration:
- 48 h
- % Adsorption:
- 82.3
- Remarks on result:
- other: IME-03G(1). vol 50 mL
- Sample no.:
- #5
- Duration:
- 48 h
- % Adsorption:
- 76.7
- Remarks on result:
- other: IME-03G(2). vol 50 mL
- Sample no.:
- #6
- Duration:
- 48 h
- % Adsorption:
- 85
- Remarks on result:
- other: IME-04A(1). vol 50 mL
- Sample no.:
- #7
- Duration:
- 48 h
- % Adsorption:
- 86
- Remarks on result:
- other: IME-04A(2). vol 50 mL
- Sample no.:
- #8
- Duration:
- 48 h
- % Adsorption:
- 86.1
- Remarks on result:
- other: LUFA 6S(1). vol 50 mL
- Sample no.:
- #9
- Duration:
- 48 h
- % Adsorption:
- 86.6
- Remarks on result:
- other: LUFA 6S(2). vol 50 mL
- Statistics:
- For the validation of the analytical method, the obtained quantification results were processed statistically and compared to requirements of the EU guidance documents.
- Validity criteria fulfilled:
- yes
- Conclusions:
- Under the conditions of the study, the test substance showed fairly high adsorption and low mobility in soils.
- Executive summary:
A study was conducted to determine the adsorption/desorption characteristics of the read across substance, N,N-bis(2-hydroxyethyl)-dodecanamide (abbreviated C12 DEA), according to OECD Guideline 406 (indirect method), in compliance with GLP. The substance was tested in five different soils at 20˚C. Test performance included the determination of: adsorption kinetics, adsorption isotherms (according to Freundlich), desorption kinetics and desorption isotherms (according to Freundlich). Pretests were performed to obtain an optimal soil to solution ratio and to check of the stability of the substance under test conditions (mass balance). Chemical analysis was performed by LC-MS/MS. As initial experiments were performed using unsterile soil conditions and the results indicated a loss of the test substance during the incubation period, subsequent experiments were performed under sterile conditions and a low amount of soil (soil:solution ratio 1:50). The mass balance subsequent to the performance of the adsorption and desorption kinetic experiments was in the range of 80 – 90% for four out of five soils. After an increase of sample size by a factor of 2, mass balance >90% could be established for all 5 soils. Consequently, the isotherm experiments were performed with the scaled-up sample size. The incubation time of 24 h was applied to reach equilibrium conditions. Four (IME-01A, IME-02A, IME-03G and IME-04A) of the five soils were provided. Sorption tests with different concentrations of the test substance were evaluated using the Freundlich equation. The tested concentration ranges were depending on soil and were approximately 55 - 5500 µg/L (soils IME-03G, IME-04A and LUFA 6S) and approximately 8 - 600 µg/L (soil IME-01A and IME-02A). Recovery of test substance from the test system was proved in a separate experiment considering an adsorption time of 23h. For four soils the recoveries were within the range of 90 – 110% and for soil IME-04A a recovery of 89% was determined. The adsorption coefficients (KF) in the adsorption tests varied up to a factor of 10 in a range between 3.7 and 36.8. Normalization to the organic carbon content of the soils results in Koc ads values from 386 to 1127. This indicates that adsorption of the substance depends on the soil organic carbon content, while no dependence on the soil pH was observed. The 1/n values obtained from the adsorption test ranged between 0.73 and 0.79 for four of the five soils. Soil IME-01A showed s lower 1/n value of 0.53. This indicates that the sorption of the substance is mostly linear. Adsorption equilibrium was achieved after 24 h for all soils. The Freundlich adsorption isotherms showed good correlations with correlation coefficients of >0.96 for all soils. Desorption was proven to be almost independent from agitation time for all soils. The correlation coefficients of desorption isotherm are moderate in the range of 0.87 – 0.95. The reason for the moderate R2 values is the low amount of soil applied due to the limited stability of the substance in the test system. 1/n varies in the range of 0.62 to 0.77. Desorption coefficients vary by a factor of 1.5 between 16.7 and 26.8. No correlation between organic carbon content of the soils and desorption could be observed since organic carbon normalized desorption coefficients differ up to a factor of about 4. Also, the soil pH value seemed not to influence the desorption behaviour. Under the conditions of the study, the test substance showed a fairly high adsorptive and low mobility in soils (Hüben, 2022).
Referenceopen allclose all
Predicted value (model result):
The estimated Koc values for the different constituents using MCI and log Kow methods were as follows:
Table 1: KOC predictions: MCI method
Constituents/Carbon chain length* |
Mean/adjusted conc |
Mole fraction Xi = (mi/Mi)/∑ (mi/Mi) |
Log Koc |
Koc (L/kg) |
Koc x Xi |
MCI |
C8 |
1.5 |
1.99E-02 |
1 |
10 |
0.198500796 |
MW (ID), Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C10 |
1.5 |
0.017703525 |
1.075546961 |
11.9 |
0.210671951 |
MW (ID), Structural fragment (Aliphatic Alcohol (-C-OH)) |
C12 |
52.5 |
0.559137624 |
1.596926814 |
39.53 |
22.10271026 |
MW (ID), Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C14 |
20 |
0.194067297 |
2.118264726 |
131.3 |
25.48103615 |
MW (ID), Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C16 |
10 |
0.089111093 |
2.639586087 |
436.1 |
38.86134787 |
MW (ID), Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C18 |
1.5 |
0.012357357 |
3.160768562 |
1448 |
17.8934529 |
MW (ID), Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C18' |
11 |
0.091115906 |
3.160768562 |
1448 |
131.9358322 |
MW (ID), Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C18'' |
2 |
0.016657117 |
3.160768562 |
1448 |
24.11950607 |
MW (ID), Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
|
|
|
|
Koc= |
260.80 |
|
|
|
|
|
Log Koc= |
2.41631268 |
|
ID: in domain, OD: out of domain; MW – molecular weight, Log Kow – partition coefficient, NA–Not applicable
*Glycerol or DEA residues have not been considered for QSAR predictions
Table 2: KOC predictions: Log Kow-based method
Constituents/Carbon chain length* |
Mean/adjusted conc |
Mole fraction Xi = (mi/Mi)/∑ (mi/Mi) |
Log Koc |
Koc (L/kg) |
Koc x Xi |
Log Kow |
C8 |
1.5 |
1.99E-02 |
0.56371834 |
3.662 |
0.072690992 |
MW (ID), log Kow (ID) Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C10 |
1.5 |
0.017703525 |
1.105850674 |
12.76 |
0.225896983 |
MW (ID), log Kow (ID) Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C12 |
52.5 |
0.559137624 |
1.653405491 |
45.02 |
25.17237581 |
MW (ID), log Kow (ID) Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C14 |
20 |
0.194067297 |
2.195346058 |
156.8 |
30.42975223 |
MW (ID), log Kow (ID) Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C16 |
10 |
0.089111093 |
2.737510691 |
546.4 |
48.69030148 |
MW (ID), log Kow (ID) Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C18 |
1.5 |
0.012357357 |
3.279666944 |
1904 |
23.52840768 |
MW (ID), log Kow (ID) Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C18' |
11 |
0.091115906 |
3.163459552 |
1457 |
132.7558754 |
MW (ID), log Kow (ID) Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
C18'' |
2 |
0.016657117 |
3.041787319 |
1101 |
18.33948632 |
MW (ID), log Kow (ID) Structural fragment (OD) - 1 out of 3 fragments (Aliphatic Alcohol (-C-OH)) |
|
|
|
|
Koc= |
279.21 |
|
|
|
|
|
Log Koc= |
2.445938414 |
|
ID: in domain, OD: out of domain; MW – molecular weight, Log Kow – partition coefficient, NA–Not applicable
*Glycerol or DEA residues have not been considered for QSAR predictions
Koc prediction results:
SMILES : CCCCCCCC(=O)N(CCO)CCO
CHEM : C8
MOL FOR: C12 H25 N1 O3
MOL WT : 231.34
--------------------------- KOCWIN v2.01 Results ---------------------------
Koc Estimate from MCI:
---------------------
First Order Molecular Connectivity Index ........... : 7.757
Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 4.6434
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -1.0277
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255
2 Aliphatic Alcohol (-C-OH) ........... : -2.6358
Corrected Log Koc .................................. : 0.5544
Over Correction Adjustment to Lower Limit Log Koc ... : 1.0000
Estimated Koc: 10 L/kg <===========
Koc Estimate from Log Kow:
-------------------------
Log Kow (Kowwin estimate) ......................... : 0.92
Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 1.4340
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -0.0038
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436
2 Aliphatic Alcohol (-C-OH) ........... : -0.8229
Corrected Log Koc .................................. : 0.5637
Estimated Koc: 3.662 L/kg <===========
SMILES : CCCCCCCCCC(=O)N(CCO)CCO
CHEM : C10
MOL FOR: C14 H29 N1 O3
MOL WT : 259.39
--------------------------- KOCWIN v2.01 Results ---------------------------
Koc Estimate from MCI:
---------------------
First Order Molecular Connectivity Index ........... : 8.757
Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 5.1647
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -1.0277
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255
2 Aliphatic Alcohol (-C-OH) ........... : -2.6358
Corrected Log Koc .................................. : 1.0757
Estimated Koc: 11.9 L/kg <===========
Koc Estimate from Log Kow:
-------------------------
Log Kow (Kowwin estimate) ......................... : 1.90
Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 1.9760
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -0.0038
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436
2 Aliphatic Alcohol (-C-OH) ........... : -0.8229
Corrected Log Koc .................................. : 1.1058
Estimated Koc: 12.76 L/kg <===========
SMILES : CCCCCCCCCCCC(=O)N(CCO)CCO
CHEM : C12
MOL FOR: C16 H33 N1 O3
MOL WT : 287.45
--------------------------- KOCWIN v2.01 Results ---------------------------
Koc Estimate from MCI:
---------------------
First Order Molecular Connectivity Index ........... : 9.757
Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 5.6860
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -1.0277
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255
2 Aliphatic Alcohol (-C-OH) ........... : -2.6358
Corrected Log Koc .................................. : 1.5970
Estimated Koc: 39.53 L/kg <===========
Koc Estimate from Log Kow:
-------------------------
Log Kow (Kowwin estimate) ......................... : 2.89
Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 2.5236
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -0.0038
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436
2 Aliphatic Alcohol (-C-OH) ........... : -0.8229
Corrected Log Koc .................................. : 1.6534
Estimated Koc: 45.02 L/kg <===========
SMILES : CCCCCCCCCCCCCC(=O)N(CCO)CCO
CHEM : C14
MOL FOR: C18 H37 N1 O3
MOL WT : 315.50
--------------------------- KOCWIN v2.01 Results ---------------------------
Koc Estimate from MCI:
---------------------
First Order Molecular Connectivity Index ........... : 10.757
Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 6.2073
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -1.0277
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255
2 Aliphatic Alcohol (-C-OH) ........... : -2.6358
Corrected Log Koc .................................. : 2.1183
Estimated Koc: 131.3 L/kg <===========
Koc Estimate from Log Kow:
-------------------------
Log Kow (Kowwin estimate) ......................... : 3.87
Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 3.0657
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -0.0038
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436
2 Aliphatic Alcohol (-C-OH) ........... : -0.8229
Corrected Log Koc .................................. : 2.1955
Estimated Koc: 156.8 L/kg <===========
SMILES : CCCCCCCCCCCCCCCC(=O)N(CCO)CCO
CHEM : C16
MOL FOR: C20 H41 N1 O3
MOL WT : 343.55
--------------------------- KOCWIN v2.01 Results ---------------------------
Koc Estimate from MCI:
---------------------
First Order Molecular Connectivity Index ........... : 11.757
Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 6.7286
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -1.0277
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255
2 Aliphatic Alcohol (-C-OH) ........... : -2.6358
Corrected Log Koc .................................. : 2.6396
Estimated Koc: 436.1 L/kg <===========
Koc Estimate from Log Kow:
-------------------------
Log Kow (Kowwin estimate) ......................... : 4.85
Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 3.6078
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -0.0038
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436
2 Aliphatic Alcohol (-C-OH) ........... : -0.8229
Corrected Log Koc .................................. : 2.7375
Estimated Koc: 546.4 L/kg <===========
SMILES : CCCCCCCCCCCCCCCCCC(=O)N(CCO)CCO
CHEM : C18
MOL FOR: C22 H45 N1 O3
MOL WT : 371.61
--------------------------- KOCWIN v2.01 Results ---------------------------
Koc Estimate from MCI:
---------------------
First Order Molecular Connectivity Index ........... : 12.757
Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 7.2499
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -1.0277
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255
2 Aliphatic Alcohol (-C-OH) ........... : -2.6358
Corrected Log Koc .................................. : 3.1609
Estimated Koc: 1448 L/kg <===========
Koc Estimate from Log Kow:
-------------------------
Log Kow (Kowwin estimate) ......................... : 5.83
Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 4.1498
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -0.0038
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436
2 Aliphatic Alcohol (-C-OH) ........... : -0.8229
Corrected Log Koc .................................. : 3.2796
Estimated Koc: 1904 L/kg <===========
SMILES : CCCCCCCCC=CCCCCCCCC(=O)N(CCO)CCO
CHEM : C18'
MOL FOR: C22 H43 N1 O3
MOL WT : 369.59
--------------------------- KOCWIN v2.01 Results ---------------------------
Koc Estimate from MCI:
---------------------
First Order Molecular Connectivity Index ........... : 12.757
Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 7.2499
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -1.0277
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255
2 Aliphatic Alcohol (-C-OH) ........... : -2.6358
Corrected Log Koc .................................. : 3.1609
Estimated Koc: 1448 L/kg <===========
Koc Estimate from Log Kow:
-------------------------
Log Kow (Kowwin estimate) ......................... : 5.62
Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 4.0337
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -0.0038
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436
2 Aliphatic Alcohol (-C-OH) ........... : -0.8229
Corrected Log Koc .................................. : 3.1634
Estimated Koc: 1457 L/kg <===========
SMILES : CCCCCC=CCC=CCCCCCCCC(=O)N(CCO)CCO
CHEM : C18''
MOL FOR: C22 H41 N1 O3
MOL WT : 367.58
--------------------------- KOCWIN v2.01 Results ---------------------------
Koc Estimate from MCI:
---------------------
First Order Molecular Connectivity Index ........... : 12.757
Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 7.2499
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -1.0277
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255
2 Aliphatic Alcohol (-C-OH) ........... : -2.6358
Corrected Log Koc .................................. : 3.1609
Estimated Koc: 1448 L/kg <===========
Koc Estimate from Log Kow:
-------------------------
Log Kow (Kowwin estimate) ......................... : 5.40
Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 3.9120
Fragment Correction(s):
1 N-CO-C (aliphatic carbon) ............ : -0.0038
2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436
2 Aliphatic Alcohol (-C-OH) ........... : -0.8229
Corrected Log Koc .................................. : 3.0418
Estimated Koc: 1101 L/kg <===========
Table 1. Results of the adsorption tests
|
Soil type* |
Soil pH** |
Adsorption coefficient KFads |
Content of org. carbon Corg |
Normalized adsorp. coeff. Kocads |
Slope (1/n) |
R2 |
Soil |
|
|
|
[%] |
|
|
|
IME-01A |
Sandy loam |
5.38 |
3.6703 |
0.95 |
386 |
0.5337 |
0.9953 |
IME-02A |
Silt loam |
6.54 |
11.5010 |
1.06 |
1085 |
0.7661 |
0.9856 |
IME-03G |
Silt loam |
5.71 |
36.8475 |
4.45 |
828 |
0.7931 |
0.9871 |
IME-04A |
Loamy sand |
5.15 |
32.5662 |
2.89 |
1127 |
0.7569 |
0.9781 |
LUFA 6S |
Clayey loam |
7.3 |
16.9073 |
1.70 |
995 |
0.7299 |
0.9637 |
*according to USDA
**in 0.01 M CaCl2
Table 2. Results of the desorption tests
|
Soil type* |
Soil pH** |
Desorption coefficient KFdes |
Content of org. carbon Corg |
Normalized desorp. coeff. Kocdes |
Slope (1/n) |
R2 |
Soil |
|
|
|
[%] |
|
|
|
IME-01A |
Sandy loam |
5.38 |
No valid data obtained |
||||
IME-02A |
Silt loam |
6.54 |
24.6753 |
1.06 |
2328 |
0.7670 |
0.8671 |
IME-03G |
Silt loam |
5.71 |
26.8220 |
4.45 |
603 |
0.6750 |
0.9467 |
IME-04A |
Loamy sand |
5.15 |
25.4161 |
2.89 |
879 |
0.6593 |
0.9370 |
LUFA 6S |
Clayey loam |
7.3 |
16.6546 |
1.70 |
980 |
0.6186 |
0.8879 |
*according to USDA
**in 0.01 M CaCl2
Recovery of the soil extraction method
Application: 32.2 µg per soil sample
|
N,N-bis(2-hydroxyethyl)-dodecan-amide in aqueous phase in sample with sterilized soil and CaCl2 solution |
||
Sample |
[µg] |
[%] |
[%] |
IME-03G(1) |
31.05 |
90.8 |
92.8 |
IME-03G(2) |
32.42 |
94.8 |
|
IME-04A(1) |
35.79 |
104.6 |
100.6 |
IME-04A(2) |
32.99 |
96.5 |
|
LUFA 6S(1) |
34.14 |
99.8 |
96.7 |
LUFA 6S(2) |
31.99 |
93.5 |
|
Mass balance
Stability at unsterile conditions
Initial soil:solution ratio finding experiment was performed as described in section 4.5 but using non-sterile soils and 0.01 M CaCl2 solution. As independent on the soil amount 100% or nearly 100% adsorption was observed, a degradation of N,N-bis(2-hydroxyethyl)-dodecanamide was assumed at unsterile test conditions. After the incubation the remaining soil from the samples with soil:solution ratio of 1:50 were extracted twice using methanol (2x20mL) and afterwards one replicate per soil with methanol + NH4OH and the other one with methanol + formic acid. Only 3 – 10 % of N,N-bis(2-hydroxyethyl)dodecanamide could be recovered from the samples, clearly indicating that the most of the applied N,N-bis(2-hydroxyethyl)-dodecanamide was degraded during the incubation of the samples.
In an additional experiment, the effects of sterilization on the stability of N,N-bis(2-hydroxyethyl)dodecanamide were tested. Two soils were used, IME 03-G and LUFA 6S, and only one soil:solution ratio of 1:50. One duplicate of samples per soil was incubated with sterilized soil, the other duplicate of samples per soil with sterilized soil and sterilized 0.01 M CaCl2 solution. Addionally control samples (0.01 M CaCl2 solution, no soil) were applied. The samples were incubated for 72 h. After incubation only the aqueous phase was analysed (no extraction of the soil residue). The results are summarized in annex A.3.2. No N,N-bis(2-hydroxyethyl)dodecanamide was recovered from the samples containing sterilized soil but non-sterilized CaCl2 solution and the recovery in the corresponding control samples was approx. 80%. In contrast 50-60% (soil IME-03G), approx. 75.0% (soil LUFA 6S) and 100-110% were recovered from the corresponding control samples. According to the obtained results the sterilization of both, soil and CaCl2 solution was necessary to reduce the degradation of N,N-bis(2-hydroxyethyl)dodecanamide during the incubation to an acceptable level. Consequently, subsequent experiments were performed with sterilized soils and sterilized CaCl2 solution.
Mass balance at sterile conditions
Mass balance with standard sample volume (50 mL)
Due to the poor recoveries obtained at unsterile incubation conditions the further experiments of this study were performed with sterilized soils. In order to prove the stability and recovery of the test substance under these conditions a mass balance was performed.
First mass balance experiment was performed subsequent to the determination of the adsorption kinetics performed with the standard sample volume of 50 mL 0.01 M CaCl2 solution. After incubation for 48 h in the adsorption step the phases were separated and the soils were extracted. The results are presented in Table 3.
Table 3: Mass balance after adsorption kinetic experiment performed with sterile soils and standard sample volume of 50 mL.
|
N,N-bis(2-hydroxyethyl)-dodecanamide in aqueous phase after adsorption experiment |
N,N-bis(2-hydroxyethyl)-dodecan-amide in soil extracts |
Total recovery of N,N-bis(2-hydroxyethyl)-dodecanamide |
|||
Sample |
[µg] |
[%] |
[µg] |
[%] |
[µg] |
[%] |
IME-01A(1) |
15.72 |
79.7 |
2.86 |
14.5 |
18.59 |
94.2 |
IME-01A(2) |
15.29 |
77.5 |
2.98 |
15.1 |
18.28 |
92.6 |
IME-02A(1)* |
|
|
* |
|
|
|
IME-02A(2) |
14.66 |
74.3 |
2.50 |
12.7 |
17.16 |
87.0 |
IME-03G(1) |
9.44 |
47.8 |
6.81 |
34.5 |
16.25 |
82.3 |
IME-03G(2) |
8.70 |
44.1 |
6.44 |
32.7 |
15.14 |
76.7 |
IME-04A(1) |
8.69 |
44.1 |
8.08 |
41.0 |
16.78 |
85.0 |
IME-04A(2) |
10.36 |
52.5 |
6.62 |
33.5 |
16.98 |
86.0 |
LUFA 6S(1) |
12.75 |
64.6 |
4.25 |
21.5 |
17.00 |
86.1 |
LUFA 6S(2) |
12.50 |
63.4 |
4.59 |
23.2 |
17.09 |
86.6 |
* sample lost during centrifugation
The recoveries of N,N-bis(2-hydroxyethyl)dodecanamide after adsorption kinetic experiment was sufficient in case of soil IME-01A and nearly sufficient for the other soils. However, especially the recovery from soil IME-03A was only between 76% and 82%. Although the results of the corresponding kinetic experiment were acceptable with respect to the determination of the incubation time to establish an equilibrium, further optimization of the incubation conditions was tested in order to increase the recoveries of N,N-bis(2-hydroxyethyl)dodecanamide.
Mass balance with increased sample volume (100 mL)
The final mass balance was performed in a separate experiment as described in section 4.6. The reason for the loss of N,N-bis(2-hydroxyethyl)dodecanamide described in section 5.2.2.2.1 was not clear, especially because sterile conditions were given. However, scaling up the experiment may also result in better recoveries. To test this possibility the final mass balance was performed with sample of double size (100 mL 0.01 M CaCl2 solution). Furthermore the incubation was limited to 24h, the time needed to needed to establish an equilibrium according to the adsorption kinetic experiment (see section 5.4). After the incubation, the phases were separated and the remaining soils were extracted. The mass balance results are shown in Table 5.
Table 5: Mass balance after adsorption kinetic experiment performed with sterile soils and increased sample volume of 100 mL.
|
N,N-bis(2-hydroxyethyl)-dodecanamide in aqueous phase after adsorption experiment |
N,N-bis(2-hydroxyethyl)-dodecan-amide in soil extracts |
Total recovery of N,N-bis(2-hydroxyethyl)-dodecanamide |
Mean total recovery of N,N-bis(2-hydroxyethyl)-dodecanamide |
|||
Sample |
[µg] |
[%] |
[µg] |
[%] |
[µg] |
[%] |
[%] |
IME-01A(1) |
30.77 |
84.2 |
5.74 |
15.7 |
36.50 |
99.9 |
93.3 |
IME-01A(2) |
26.13 |
71.5 |
5.61 |
15.3 |
31.74 |
86.8 |
|
IME-02A(1) |
29.87 |
81.7 |
3.92 |
10.7 |
33.79 |
92.4 |
92.4* |
IME-02A(2) |
23.79 |
65.1 |
3.54 |
9.7 |
27.33 |
74.8 |
|
IME-03G(1) |
21.72 |
59.4 |
13.15 |
36.0 |
34.87 |
95.4 |
91.7 |
IME-03G(2) |
18.20 |
49.8 |
13.98 |
38.2 |
32.18 |
88.0 |
|
IME-04A(1) |
20.04 |
54.8 |
14.37 |
39.3 |
34.41 |
94.1 |
89.4 |
IME-04A(2) |
18.24 |
49.9 |
12.67 |
34.7 |
30.91 |
84.6 |
|
LUFA 6S(1) |
29.30 |
80.2 |
7.23 |
19.8 |
36.54 |
100 |
97.6 |
LUFA 6S(2) |
27.78 |
76.0 |
7.07 |
19.3 |
34.84 |
95.3 |
|
* replicate IME-02A(2) not considered
The recoveries of N,N-bis(2-hydroxyethyl)dodecanamide were > 90% or nearly 90% for the most samples. The only exception was the sample IME-02-A(2) with 74.8% recovery. As the recovery for this sample is significantly differing from the other samples, an experimental error, most probably an application error, is assumed in this case. The mean recovery values for all soils are > 89% and confirm the stability of N,N-bis(2-hydroxyethyl)dodecan-amide within the experimental incubation time.
Furthermore, the recoveries observed with the increased sample size were better compared to the experiments with the standard sample size. Consequently, the determination of the adsorption and desorption isotherm was performed with the increased sample size.
Description of key information
Key value for chemical safety assessment
- Koc at 20 °C:
- 260.8
Additional information
The soil adsorption and desorption potential (Koc) of the test substance, C12-18 and C18-unsatd. DEA, was estimated using both the Molecular Connectivity Index (MCI) and the Log Kow methods of the KOCWIN v 2.01 program (EPISuite v 4.11). Since the test substance is an UVCB, the Koc values were estimated for individual constituents using SMILES codes as the input parameter. The predicted Koc values for all the constituents ranged from 10 to 1448 L/kg (MCI) and 3.66 to 1904 (log Kow) L/kg, respectively. The corresponding log Koc values ranged from 1 to 3.16 (MCI) and 0.56 to 3.28 (Kow) (US EPA, 2019). Given that the constituents are structurally very similar and vary only in the carbon chain length, a weighted average value, which considers the percentage of each constituent in the substance, was calculated to dampen the errors in predictions. The weighted average Koc values were calculated as 260.80 L/kg (log Koc = 2.41) and 279.21 L/kg (log Koc = 2.44), using the MCI and log Kow methods, respectively. Based on the above information, the test substance is expected to have a moderate adsorption potential (US EPA, 2012) to soil and sediment, leading to slow migration to groundwater. Overall, the Koc predictions for the test substance using KOCWIN model of EPI Suite TM can be considered ‘reliable with moderate confidence as not all constituents met the MW and structural fragment molecular descriptor domain criteria as defined in the KOCWIN v 2.01 user guide of EPI Suite TM.
The MCI value (Koc = 260.80 L/kg, log Koc = 2.41) was selected as key for risk assessment purposes since this method is more appropriate for surface active substances.
A supporting study was conducted to determine the adsorption/desorption characteristics of the read across substance, N,N-bis(2-hydroxyethyl)-dodecanamide (abbreviated C12 DEA), according to OECD Guideline 406 (indirect method), in compliance with GLP. The substance was tested in five different soils at 20˚C. Test performance included the determination of: adsorption kinetics, adsorption isotherms (according to Freundlich), desorption kinetics and desorption isotherms (according to Freundlich). Pretests were performed to obtain an optimal soil to solution ratio and to check of the stability of the substance under test conditions (mass balance). Chemical analysis was performed by LC-MS/MS. As initial experiments were performed using unsterile soil conditions and the results indicated a loss of the test substance during the incubation period, subsequent experiments were performed under sterile conditions and a low amount of soil (soil:solution ratio 1:50). The mass balance subsequent to the performance of the adsorption and desorption kinetic experiments was in the range of 80 – 90% for four out of five soils. After an increase of sample size by a factor of 2, mass balance >90% could be established for all 5 soils. Consequently, the isotherm experiments were performed with the scaled-up sample size. The incubation time of 24 h was applied to reach equilibrium conditions. Four (IME-01A, IME-02A, IME-03G and IME-04A) of the five soils were provided. Sorption tests with different concentrations of the test substance were evaluated using the Freundlich equation. The tested concentration ranges were depending on soil and were approximately 55 - 5500 µg/L (soils IME-03G, IME-04A and LUFA 6S) and approximately 8 - 600 µg/L (soil IME-01A and IME-02A). Recovery of test substance from the test system was proved in a separate experiment considering an adsorption time of 23h. For four soils the recoveries were within the range of 90 – 110% and for soil IME-04A a recovery of 89% was determined. The adsorption coefficients (KF) in the adsorption tests varied up to a factor of 10 in a range between 3.7 and 36.8. Normalization to the organic carbon content of the soils results in Koc ads values from 386 to 1127. This indicates that adsorption of the substance depends on the soil organic carbon content, while no dependence on the soil pH was observed. The 1/n values obtained from the adsorption test ranged between 0.73 and 0.79 for four of the five soils. Soil IME-01A showed s lower 1/n value of 0.53. This indicates that the sorption of the substance is mostly linear. Adsorption equilibrium was achieved after 24 h for all soils. The Freundlich adsorption isotherms showed good correlations with correlation coefficients of >0.96 for all soils. Desorption was proven to be almost independent from agitation time for all soils. The correlation coefficients of desorption isotherm are moderate in the range of 0.87 – 0.95. The reason for the moderate R2 values is the low amount of soil applied due to the limited stability of the substance in the test system. 1/n varies in the range of 0.62 to 0.77. Desorption coefficients vary by a factor of 1.5 between 16.7 and 26.8. No correlation between organic carbon content of the soils and desorption could be observed since organic carbon normalized desorption coefficients differ up to a factor of about 4. Also, the soil pH value seemed not to influence the desorption behaviour. Under the conditions of the study, the test substance showed fairly high adsorption and low mobility in soils (Hüben, 2022).
The results of the testing are in line with those obtained from modeling with the KOCWIN v 2.01 program of EPISuite v 4.11.
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