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Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29-10-2013 to 09-12-2013

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Remarks:

The OECD TG 106 guideline study was conducted under GLP ; however no GLP claim is made, as the completion of the full study was determined to be ‘not technically feasible’. Therefore the ‘calculation method’ was adopted using US EPA KOCWIN v2.00, with results justified based on totality of information.

Qualifier:

according to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.18 (Adsorption / Desorption Using a Batch Equilibrium Method)

Deviations:

no

GLP compliance:

not specified

Remarks:

The OECD TG 106 guideline study was conducted under GLP ; however no GLP claim is made, as the completion of the full study was determined to be ‘not technically feasible’.

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

no

Test temperature:

22 ± 2°C typical ; laboratory ambient temperature and, typically, at a constant temperature between 20°C and 25°C

Analytical monitoring:

yes

Remarks:

It was determined: a sufficiently reliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible.

Details on sampling:

- Concentrations:
For the preliminary test : soil samples were conditioned. Samples for adsorption 40 μL of a 200 μg/L spiking solution were added in order to adjust the test concentration of 200 ng/L. Afterwards, the samples were agitated for 2 hours. Samples for analysis were subsequently extracted. For further information see below fields.
- Sampling interval: See above and below.
- Sample storage conditions before analysis: On the autosampler prior to analysis (< 24 hours duration).
- Other: To prove the feasibility of quantification in the aqueous phase, preliminary investigations were performed with the test item in soil LUFA 2.2. Only a low concentration of 200 ng/L could be applied to the soil suspension, based on the low water solubility (from study cited in the study report) of the test item as the applied concentration should be lower than half of the determined water solubility. A lower limit of quantification (LOQ) of 10 ng/L could be implemented for the test item using GC-MS/MS. Concentrations in the aqueous phase are only detectable (above LOQ), if the adsorption to soil is lower than 97.5%. However, the adsorption was higher than this in preliminary tests using a soil / solution ratio of 1:20. Therefore results could only be approximated based on the lowest calibration level of the analytical method. The completion of the full study was determined to be ‘not technically feasible’. In preliminary tests using a soil / solution ratio of 1:20, the measured values for the aqueous phase were below the limit of quantification of the analytical method. Even if the ratio were to be lowered to 1:100 to be able to detect test item concentrations above the LOQ for one concentration level 200 ng/L, determination of Freundlich isotherms would not be possible due to analytical limitations. It was determined: a sufficiently reliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. On this basis the definitive test was not conducted, and the calculation method was used to assess the adsorption coefficient. Concerning investigations of the mass balance, no reproducible extraction method for soil could be implemented. See below for further information.

Matrix no.:

#1

Matrix type:

loamy sand

% Clay:

8.5

% Silt:

11.3

% Sand:

80.2

% Org. carbon:

1.47

pH:

5.4

CEC:

7.6 meq/100 g soil d.w.

Details on matrix:

COLLECTION AND STORAGE
- Geographic location: Not reported. LUFA 2.2 was provided by LUFA (characteristics / analysis sheet provided by LUFA)
- Collection procedures: Not reported.
- Sampling depth (cm): Not reported.
- Storage conditions: Not reported. However, would be in line with soil supplier instructions.
- Storage length: Not reported (although LUFA 2.2 (characteristics / analysis sheet provided by LUFA)
- Soil preparation (e.g.: 2 mm sieved; air dried etc.): 2.0 g LUFA 2.2 was weighed into glass test vessels and soil samples 40 mL of 0.01 M CaCl2-solution was added.
(conditioning) After agitation overnight (12 hours minimum), the samples were used for adsorption experiments (‘preliminary test’).

PROPERTIES
See “Details on Matrix”. Additionally see attached background material.

Details on test conditions:

TEST CONDITIONS
- Buffer: Not applicable.
- pH: The pH of the supernatants was not determined (full study not conducted).
- Suspended solids concentration: Not applicable.
- other: Experiments were conducted. Different conditions and test systems were used in the determination of each parameter. Described further, as appropriate.
For the preliminary test : soil samples were conditioned. Samples for adsorption 40 μL of a 200 μg/L spiking solution were added in order to adjust the test concentration of 200 ng/L. Afterwards, the samples were agitated for 2 hours. Samples for analysis were subsequently extracted. It was determined: a sufficiently reliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. On this basis the definitive test was not conducted, and the calculation method was used to assess the adsorption coefficient. Concerning investigations of the mass balance, no reproducible extraction method for soil could be implemented. See below for further information.

TEST SYSTEM
- Type, size and further details on reaction vessel: Not reported.
- Water filtered (i.e. yes/no; type of size of filter used, if any): Ultra pure water (produced in house).
- Amount of soil/sediment/sludge and water per treatment (if simulation test): Not applicable.
- Soil/sediment/sludge-water ratio (if simulation test): Not applicable.
- Number of reaction vessels/concentration: See Details on Sampling.
- Measuring equipment: See identification and quantification of the test substance/product and other fields.
- Test performed in closed vessels due to significant volatility of test substance: Closed vessel use is presumed.
- Method of preparation of test solution: See Details on Sampling.
- Are the residues from the adsorption phase used for desorption: Not applicable.
- Other: Not applicable. A full definitive study was not performed. It was determined: a sufficiently reliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. Therefore the ‘calculation method’ was adopted using US EPA KOCWIN v2.00, with results justified based on totality of information.

Computational methods:

- Adsorption and desorption coefficients (Kd): The adsorption coefficients Kd and Koc would typically be obtained from the adsorption kinetics experiment in the definitive test and calculated as follows :
Kd = Cs (eq)/Caq (eq)
and
Koc = Kd x 100 / %OC
- Freundlich adsorption and desorption coefficients: The Freundlich adsorption isotherm parameters (KFads and 1/nads) would be calculated by fitting the Freundlich isotherm to the data.
Cs(eq) = KF ∙ Caq(eq)1/n
- Slope of Freundlich adsorption/desorption isotherms: Not applicable.
- Adsorption coefficient per organic carbon (Koc): See above.
- Regression coefficient of Freundlich equation. See above.
- Other: The completion of the full study was determined to be ‘not technically feasible’. In preliminary tests using a soil / solution ratio of 1:20, the measured values for the aqueous phase were below the limit of quantification of the analytical method. Even if the ratio were to be lowered to 1:100 to be able to detect test item concentrations above the LOQ for one concentration level 200 ng/L, determination of Freundlich isotherms would not be possible due to analytical limitations. It was determined: a sufficiently reliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. Therefore the ‘calculation method’ was adopted using US EPA KOCWIN v2.00, with results justified based on totality of information.

Sample No.:

#1

Type:

log Koc

Value:

> 4.75 dimensionless

pH:

5.4

Temp.:

20 °C

Matrix:

LUFA 2.2 - Loamy sand

% Org. carbon:

1.47

Remarks on result:

other: Koc = > 57178 L/kg

Remarks:

Preliminary test results in LUFA 2.2. : estimates based on observed results (see tables for further information)

Key result

Type:

log Koc

Value:

>= 5.111 - <= 5.34 dimensionless

pH:

7

Temp.:

25 °C

Matrix:

Soil

Remarks on result:

other: Koc : >= 1.21x10^5 - <= 2.189x10^5 L/kg ; Calculated Log Koc from US EPA KOCWIN v2.00

Remarks:

range using MCI and/or Kow methods

Recovery of test material:

Concerning investigations of the mass balance, no reproducible extraction method for soil could
be implemented. If water-miscible solvents (acetonitrile, methanol, acetone) were used, no substance was extracted. Cyclohexane and dichloromethane were also tested, because these solvents worked for extraction of the aqueous phase. But as these solvents are not water miscible, difficulties with handling occurred due to the pore water in the wet soil, which subsequently led to problems with reproducibility. It was determined: a sufficiently reliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible.

Transformation products:

not measured

Details on results (Batch equilibrium method):

PRELIMINARY TEST
- Sample purity: See ‘test material information’
- Weighed soil: Soil : For the preliminary test : 2.0 g LUFA 2.2 was weighed into glass test vessels and soil samples 40 mL of 0.01 M CaCl2-solution was added.
(conditioning) After agitation overnight (12 hours minimum), the samples were used for adsorption experiments. Samples for adsorption 40 μL of a 200 μg/L spiking solution were added in order to adjust the test concentration of 200 ng/L. Afterwards, the samples were agitated for 2 hours. Samples for analysis were subsequently extracted. It was determined: a sufficiently reliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. On this basis the definitive test was not conducted, and the calculation method was used to assess the adsorption coefficient. Concerning investigations of the mass balance, no reproducible extraction method for soil could be implemented. See below for further information.
- Volume of CaCl2 solution: In preliminary test : diluted with 40 mL 0.01M CaCl2 solution
- Initial test substance concentration: In preliminary test : 40 μL of a 200 μg/L spiking solution were added in order to adjust the test concentration of 200 ng/L test item.
- Test substance concentration in final solution: See above.
- Analytical test substance concentration in final solution: Analysed concentrations are reported.
- Other: The completion of the full study was determined to be ‘not technically feasible’. In preliminary tests using a soil / solution ratio of 1:20, the measured values for the aqueous phase were below the limit of quantification of the analytical method. Even if the ratio were to be lowered to 1:100 to be able to detect test item concentrations above the LOQ for one concentration level 200 ng/L, determination of Freundlich isotherms would not be possible due to analytical limitations. It was determined: a sufficiently reliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. Therefore the ‘calculation method’ was adopted using US EPA KOCWIN v2.00, with results justified based on totality of information.

MAIN TEST: PERFORMANCE
- Test material stability during adsorption/desorption phase: Not applicable. Could not be performed.
- Experimental conditions maintained throughout the study: Not applicable.
- Buffer/test substance interactions affecting sorption: Not applicable.
- Further chemical interactions: Not applicable.
- Buffer-catalyzed degradation of test substance: Not applicable.
- Anomalies or problems encountered (if yes): Not applicable.
- Other observations: None.

TRANSFORMATION PRODUCTS
- Range of maximum concentrations in % of the applied amount: Not applicable.

RESIDUES
- Total unidentified radioactivity (range) of applied amount: Not applicable.
- Extractable residues (% of applied amount at end of study period): Not applicable.
- Non-extractable residues (% of applied amount at end of study period): Not applicable.

VOLATILIZATION
- % of the applied radioactivity present as volatile organics at end of study: Not applicable.

RESULTS OF SUPPLEMENTARY EXPERIMENT (if any): Not applicable.

Table 1. Preliminary Test : Adsorption and Mass Balance – LUFA 2.2

Notes: nominal concentration, test item: 200 ng/L; soil / solution ratio 1:20, msoil = 1.86 g, V = 40 mL; sampling point 2 h; OC = 1.47%; n = 2

Adsorption [%] #1	Extraction Solvent	Recovery soil [%] #2	Koc approximate [L/kg] #3	Log Koc approximate #3
> 97.5	Acetone	< 1.25	> 5.7178	> 4.75
> 97.5	Cyclohexane	< 1.25	> 5.7178	> 4.75
> 97.5	Dichloromethane	< 1.25	> 5.7178	> 4.75

#1: determined from the aqueous phase; measured concentration was below lowest calibration level (5 ng/L)

#2: measured concentration was below lowest calibration level (5 ng/L)

#3: calculated with lowest calibration level

 

A reliable and sensitive analytical method for the test item in the aqueous phase during the experiments is mandatory for the calculation of the study endpoints for the batch equilibrium method of assessing adsorption/desorption (OECD TG 106). In preliminary tests using a soil / solution ratio of 1:20, the measured values for the aqueous phase were below the limit of quantification of the analytical method. Even if the ratio would be lowered to 1:100 to be able to detect test item concentrations above the LOQ for one concentration level 200 ng/L, a determination of Freundlich isotherms would not be possible due to analytical limitations. As the test item was considered to be highly adsorptive, determination of the fraction adsorbed to the solid phase is essential. As described above, no reproducible extraction method for soil could be implemented. In conclusion, it was technically unfeasible to carry out the batch equilibrium method (OECD TG 106) with the test item.

 

Therefore the ‘calculation method’ was adopted using US EPA KOCWIN v2.00, with results justified based on totality of information. The output of the calculation are provided below.

 

Figure 1. : Output of US EPA KOCWIN v2.0

SMILES : CCCCCCCCCC(C)=COCCc1ccccc1

CHEM  :

MOL FOR: C20 H32 O1

MOL WT : 288.48

--------------------------- KOCWIN v2.00 Results ---------------------------

 Koc Estimate from MCI:

 ---------------------

        First Order Molecular Connectivity Index ........... : 10.326

        Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 5.9826

        Fragment Correction(s):

                 1  Ether, aliphatic (-C-O-C-) .......... : -0.8716

        Corrected Log Koc .................................. : 5.1110

                        Estimated Koc: 1.291e+005 L/kg  <===========

 

 Koc Estimate from Log Kow:

 -------------------------

        Log Kow (User entered  ) ......................... : 8.15

        Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 5.4309

        Fragment Correction(s):

                 1  Ether, aliphatic (-C-O-C-) .......... : -0.0906

        Corrected Log Koc .................................. : 5.3403

                        Estimated Koc: 2.189e+005 L/kg  <===========

Validity criteria fulfilled:

yes

Conclusions:

The test item adsorption coefficient (log Koc) for three different soils according to OECD Guideline 106 was Speyer 2.2 (loamy sand): 3.06, Speyer 2.3 (sandy loam): 3.3 and Speyer 6S (clay): 3.03 at 20 ± 2°C.

Executive summary:

The test item adsorption coefficient (log Koc) for soil according to OECD TG 106 was attempted to be determined. In a preliminary test using LUFA 2.2 (sandy loam), 2.0 g LUFA 2.2 was weighed into glass test vessels and soil samples 40 mL of 0.01 M CaCl2-solution was added for soil conditioning. After agitation overnight (12 hours minimum), the samples were used for adsorption experimentation. Samples for adsorption 40 μL of a 200 μg/L spiking solution were added in order to adjust the test concentration of 200 ng/L. Afterwards, the samples were agitated for 2 hours. Samples for analysis were subsequently extracted. The soil suspensions were centrifuged at the end of the adsorption experiment for 5 minutes at 2000 rpm to separate the phases, followed by analysing the concentration of the test item in the aqueous phase. For analysis of the soil, the aqueous phase was decanted and the soil was extracted. Specifically, for the aqueous phase: 15 mL sample was filled into a separate vial. Afterwards, 1.5 mL cyclohexane and approx. 1.5 g sodium chloride were added. The vial was sealed and shaken for 2 min. After drying with sodium sulphate, the samples were analysed directly by the GC-MS method described below. For the solid phase: after removal of as much aqueous phase as possible, the soil replicates were extracted for 30 min with 8 mL Acetone. The supernatant was filled into a measuring flask and the soil was extracted for two additional cycles (30 minutes and overnight) with extraction media a) acetone, b) cyclohexane or c) dichloromethane to compare the different extraction solvents. The collected and combined extracts per replicate were evaporated to approx. 0.5 mL residue, filled to a 2 mL measuring flask and filled up to the mark with blank extract. An aliquot of 100 μL was spiked by the analytical system into 10 mL ultrapure water containing 10 g sodium chloride and measured by the GC-MS method that had previously been validated.It was determined: a sufficientlyreliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. Concerning investigations of the mass balance, no reproducible extraction method for soil could be implemented. Using a soil / solution ratio of 1:20, the measured values for the aqueous phase were below the limit of quantification of the analytical method. Even if the ratio were to be lowered to 1:100 to be able to detect test item concentrations above the LOQ for one concentration level 200 ng/L, determination of Freundlich isotherms would not be possible due to analytical limitations.It was determined: a sufficientlyreliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. Therefore the ‘calculation method’ was adopted using US EPA KOCWIN v2.00, with results justified based on totality of information.A predicted log Koc between 5.111 (MCI method) and 5.340 (KOW method) was calculated which is in-line with the results obtained from preliminary tests (log Koc > 4.75) using LUFA 2.2 (sandy loam). It was therefore considered the conclusion was reliable.

Reference 2

Endpoint:

adsorption / desorption: screening

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
In accordance with REACH Regulation (EC) No. 1907/2006 Annex IX, section 9.3.3 and Annex XI section 2, further testing does not need to be conducted if it is technically not feasible to conduct the test. The test item adsorption coefficient (log Koc) for to soil according to OECD TG 106 batch equilibrium method, was attempted to be determined. However, it was found no validated analytical method of sufficient reliability and sensitivity could be provided with which to conduct the full OECD TG 106 batch equilibrium method study. On this basis the ‘calculation method’ was adopted using US EPA KOCWIN v2.00, with results justified based on totality of information, and in accordance with Annex VIII, section 9.3.1, and related sections: sufficient information being already available for environmental risk assessment. The conclusion is the substance has a Log Koc, soil : ≥ 5.111 and ≤ 5.340 at 25 °C; ca. pH 7, which can be used as suitable limit values. The substance lacks relevant basic or acid moieties and/or potential for significant dissociation (i.e. greater than 10% within the pH range of 5.5 to 7.5). The substance presents a neutral molecular form over the whole of the environmentally relevant pH range. Additionally, there is evidence that the substance ‘rapidly degrades’ in available studies (OECD TG 301F neat and with silicone oil emulsifier). According to ECHA Guidance on Information Requirements and Chemical Safety Assessment (Chapter R.7a: Endpoint Specific Guidance, R.7.1.15, July 2017) further testing does not need to be conducted.

Reason / purpose for cross-reference:

data waiving: supporting information

Reason / purpose for cross-reference:

reference to other study

Reason / purpose for cross-reference:

reference to other study

Reason / purpose for cross-reference:

reference to other study

Description of key information

Conclusion: Log Koc, soil : ≥ 5.111 and ≤ 5.340 at 25 °C; ca. pH 7

 

1. log Koc = > 4.75 (Koc: > 57178 L/kg): LUFA 2.2 sandy loam: pH 5.4 at 22 ± 2°C and 1 atm, preliminary test OECD TG 106, 2020

2. It was determined: a sufficiently reliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. Therefore the ‘calculation method’ was adopted using US EPA KOCWIN v2.00, with results justified based on totality of information.

3. Log Koc, soil : ≥ 5.111 (MCI method) and ≤ 5.340 (KoW method) at 25 °C; ca. pH 7, Calculation – US EPA KOCWIN v2.00, 2020

Supporting information:

The substance lacks relevant basic or acid moieties and/or potential significant dissociation (i.e. greater than 10% within the pH range of 5.5 to 7.5). The substance presents a neutral molecular form over the whole of the environmentally relevant pH range.

Additional information

Key study : attempted OECD TG 106 / calculated KOC from US EPA KOCWIN v2.00 , 2020 : The test item adsorption coefficient (log Koc) for soil according to OECD TG 106 was attempted to be determined. In a preliminary test using LUFA 2.2 (sandy loam), 2.0 g LUFA 2.2 was weighed into glass test vessels and soil samples 40 mL of 0.01 M CaCl2-solution was added for soil conditioning. After agitation overnight (12 hours minimum), the samples were used for adsorption experimentation. Samples for adsorption 40 μL of a 200 μg/L spiking solution were added in order to adjust the test concentration of 200 ng/L. Afterwards, the samples were agitated for 2 hours. Samples for analysis were subsequently extracted. The soil suspensions were centrifuged at the end of the adsorption experiment for 5 minutes at 2000 rpm to separate the phases, followed by analysing the concentration of the test item in the aqueous phase. For analysis of the soil, the aqueous phase was decanted and the soil was extracted. Specifically, for the aqueous phase: 15 mL sample was filled into a separate vial. Afterwards, 1.5 mL cyclohexane and approx. 1.5 g sodium chloride were added. The vial was sealed and shaken for 2 min. After drying with sodium sulphate, the samples were analysed directly by the GC-MS method described below. For the solid phase: after removal of as much aqueous phase as possible, the soil replicates were extracted for 30 min with 8 mL Acetone. The supernatant was filled into a measuring flask and the soil was extracted for two additional cycles (30 minutes and overnight) with extraction media a) acetone, b) cyclohexane or c) dichloromethane to compare the different extraction solvents. The collected and combined extracts per replicate were evaporated to approx. 0.5 mL residue, filled to a 2 mL measuring flask and filled up to the mark with blank extract. An aliquot of 100 μL was spiked by the analytical system into 10 mL ultrapure water containing 10 g sodium chloride and measured by the GC-MS method that had previously been validated.It was determined: a sufficientlyreliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. Concerning investigations of the mass balance, no reproducible extraction method for soil could be implemented. Using a soil / solution ratio of 1:20, the measured values for the aqueous phase were below the limit of quantification of the analytical method. Even if the ratio were to be lowered to 1:100 to be able to detect test item concentrations above the LOQ for one concentration level 200 ng/L, determination of Freundlich isotherms would not be possible due to analytical limitations.It was determined: a sufficientlyreliable and sensitive analytical method for the test item in the aqueous phase was not technically feasible. Therefore the ‘calculation method’ was adopted using US EPA KOCWIN v2.00, with results justified based on totality of information.A predicted log Koc between 5.111 (MCI method) and 5.340 (KOW method) was calculated which is in-line with the results obtained from preliminary tests (log Koc > 4.75) using LUFA 2.2 (sandy loam). It was therefore considered the conclusion was reliable.

Supporting information:

In accordance with REACH Regulation (EC) No. 1907/2006 Annex IX, section 9.3.3 and Annex XI section 2, further testing does not need to be conducted if it is technically not feasible to conduct the test. The test item adsorption coefficient (log Koc) for to soil according to OECD TG 106 batch equilibrium method, was attempted to be determined. However, it was found no validated analytical method of sufficient reliability and sensitivity could be provided with which to conduct the full OECD TG 106 batch equilibrium method study. On this basis the ‘calculation method’ was adopted using US EPA KOCWIN v2.00, with results justified based on totality of information, and in accordance with Annex VIII, section 9.3.1, and related sections: sufficient information being already available for environmental risk assessment. The conclusion is the substance has a Log Koc, soil : ≥ 5.111 and ≤ 5.340 at 25 °C; ca. pH 7, which can be used as suitable limit values. The substance lacks relevant basic or acid moieties and/or potential for significant dissociation (i.e. greater than 10% within the pH range of 5.5 to 7.5). The substance presents a neutral molecular form over the whole of the environmentally relevant pH range. Additionally, there is evidence that the substance ‘rapidly degrades’ in available studies (OECD TG 301F neat and with silicone oil emulsifier). According to ECHA Guidance on Information Requirements and Chemical Safety Assessment (Chapter R.7a: Endpoint Specific Guidance, R.7.1.15, July 2017) further testing does not need to be conducted.