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Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

other: Expert Statement

Adequacy of study:

key study

Study period:

Not reported

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Deviations:

no

GLP compliance:

not specified

Radiolabelling:

no

Key result

Type:

log Koc

Remarks on result:

not determinable because of methodological limitations

Remarks:

The test material was insoluble in all four organic solvent-water mixes, therefore a determination of the Log Koc is according to guideline technically not possible.

Pre-test without column

- UV detector:

First, UV activity of the test material, at ʎ=230 nm and 254 nm (Eluent methanol / water 75 % / 25 %), was tested.

The wavelengths selected for detection show sufficient absorption both for the test material and for the reference substances.

For this purpose, a 2 g/L test standard solution in methanol, without HPLC column, was tested.

The measurements without column show a strong signal in the UV detector, while the RI detector shows no signal and the ELSD detector shows a weak signal.

 

Pre-test with column

- Phenomenex Luna C18, 3µ, 100 x 4.6 mm (Pre-tests Log Pow):

After this, the test material was attempted to elute first from the column (Phenomenex Luna C18, 3 µ, 100 x 4.6 mm) in guideline conformity with an eluent of 75 % methanol and 25 % water (flow rate 0.8 mL/min; 25 °C) and after 40 minutes an additional rinsing step with 100 % methanol.

A second run with the same conditions detected with ELSD shows also no signal

In a further experiment with the mobile phase 75 % isopropanol / 25 % water (flow rate 0.8 mL/min; 25 °C) and after 40 minutes an additional rinsing step with 100 % isopropanol no signals could be detected.

 

- Reprosil Pur CN, 3µ, 125 x 4.6 mm (Pre-Tests Log Koc):

As with the C18 column the test material was attempted to elute first from the column (Reprosil Pur CN, 3µ, 125 x 4.6 mm) in guideline conformity with an eluent of 55 % methanol and 45 % water (flow rate 0.8 mL/min; 25 °C).

In a further experiment with the mobile phase 55 % isopropanol / 45 % water (flow rate 0.8 mL/min; 25 °C) and after 30 minutes an additional rinsing step with 100 % isopropanol no signals could be detected.

 

Summary and conclusions

The test material is only soluble in pure methanol, moderately UV active (without a column an absorption was detectable) and under the conditions, given by the guideline, probably not or so slowly eluted from the column that it cannot be detected. In addition, determination with RI and ELSD is not possible because no signals could be detected.

Validity criteria fulfilled:

not applicable

Conclusions:

The test material was insoluble in all four organic solvent-water mixes, therefore a determination of the Log Koc is according to guideline technically not possible.

Executive summary:

The test material is a UVCB, therefore the determination of the Log Koc can only be carried out according to OECD guideline 121 and EU Method C19.

According to the guidelines, the test material should be dissolved in mobile phase methanol­water with a water content of at least 25 % for the determination of Log Pow. This is not possible because the test material precipitated in mobile phase methanol-water (75 % / 25 % and 55 % / 45 %). Even with the other solvents provided in the Guideline: acetonitrile, ethanol and isopropanol, no clear solution could be obtained after the addition of at least 25 % resp. 45 % water.

However, a clear solution could be obtained in pure methanol at a maximum concentration of 5 g/L in contrast to the solubility tests in pure acetonitrile in which the test material does not dissolve.

The test material was insoluble in all four organic solvent-water mixes, therefore a determination of the Log Koc is according to guideline technically not possible. Nevertheless, pre-tests with methanol solution in several concentrations were performed. Three different detectors (UV, ELSD and RI) were used, but no signals could be detected.

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Qualifier:

no guideline followed

Principles of method if other than guideline:

The Log soil adsorption coefficient (Log Koc) of the test material was estimated from the KOW.

GLP compliance:

no

Remarks:

No laboratory work was performed in this study. GLP is therefore not required.

Type of method:

other: calculation method (fragments)

Key result

Type:

Koc

Value:

2 040 000 000 L/kg

Remarks on result:

other: Component 1: N-{2-[(2-{[2-(2-nonadecyl-4,5-dihydro-1H-imidazol-1-yl)ethyl]amino}ethyl)amino]ethyl}octadecanamide

Key result

Type:

Koc

Value:

608 000 L/kg

Remarks on result:

other: Component 2: N-(2-{[2-({2-[N-(2-hydroxyethyl)hexadecanimidamido]ethyl}amino)ethyl]amino}ethyl)octadecanamide

Key result

Type:

Koc

Value:

166 000 000 L/kg

Remarks on result:

other: Component 3: N-{2-[(2-{[2-(2-pentadecyl-4,5-dihydro-1H-imidazol-1-yl)ethyl]amino}ethyl)amino]ethyl}octadecanamide

Key result

Type:

Koc

Value:

127 000 000 L/kg

Remarks on result:

other: Component 4: N-{2-[(2-{[2-(2-pentadecyl-4,5-dihydro-1H-imidazol-1-yl)ethyl]amino}ethyl)amino]ethyl}octadecenamide

Key result

Type:

Koc

Value:

2 040 000 000 L/kg

Remarks on result:

other: Component 5: N-{2-[(2-{[2-(2-heptadecyl-4,5-dihydro-1H-imidazol-1-yl)ethyl]amino}ethyl)amino]ethyl}icosanamide

Key result

Type:

Koc

Value:

109 000 000 000 L/kg

Remarks on result:

other: Component 6: 2-{N-[2-({2-[(2-octadecanamidoethyl)amino]ethyl}amino)ethyl]hexadecanimidamido}ethyl octadecanoate

Key result

Type:

Koc

Value:

30 800 000 000 L/kg

Remarks on result:

other: Component 7: 2-{N-[2-({2-[(2-hexadecanamidoethyl)amino]ethyl}amino)ethyl]hexadecanimidamido}ethyl octadecanoate

Key result

Type:

Koc

Value:

442 000 000 L/kg

Remarks on result:

other: Component 8: N-{2-[(2-{[2-(2-heptadecyl-4,5-dihydro-1H-imidazol-1-yl)ethyl]amino}ethyl)amino]ethyl}octadecenamide

Key result

Type:

Koc

Value:

578 000 000 L/kg

Remarks on result:

other: Component 9: N-{2-[(2-{[2-(2-heptadecyl-4,5-dihydro-1H-imidazol-1-yl)ethyl]amino}ethyl)amino]ethyl}octadecanamide

Key result

Type:

Koc

Value:

166 000 000 L/kg

Remarks on result:

other: Component 10: N-{2-[(2-{[2-(2-heptadecyl-4,5-dihydro-1H-imidazol-1-yl)ethyl]amino}ethyl)amino]ethyl}hexadecanamide

The test material is a UVCB substance composed of 10 main components which have been used to estimate the Koc of the test material.

The Koc for component 1 was estimated to be 2.04E+09 L/kg.

The Koc for component 2 was estimated to be 6.08E+05 L/kg.

The Koc for component 3 was estimated to be 1.66E+08 L/kg.

The Koc for component 4 was estimated to be 1.27E+08 L/kg.

The Koc for component 5 was estimated to be 2.04E+09 L/kg.

The Koc for component 6 was estimated to be 1.09E+11 L/kg.

The Koc for component 7 was estimated to be 3.08E+10 L/kg.

The Koc for component 8 was estimated to be 4.42E+08 L/kg.

The Koc for component 9 was estimated to be 5.78E+08 L/kg.

The Koc for component 10 was estimated to be 1.66E+08 L/kg.

Validity criteria fulfilled:

not applicable

Conclusions:

The test material is a UVCB substance composed of 10 main components which have been used to estimate the Koc of the test material.
The Koc for component 1 was estimated to be 2.04E+09 L/kg.
The Koc for component 2 was estimated to be 6.08E+05 L/kg.
The Koc for component 3 was estimated to be 1.66E+08 L/kg.
The Koc for component 4 was estimated to be 1.27E+08 L/kg.
The Koc for component 5 was estimated to be 2.04E+09 L/kg.
The Koc for component 6 was estimated to be 1.09E+11 L/kg.
The Koc for component 7 was estimated to be 3.08E+10 L/kg.
The Koc for component 8 was estimated to be 4.42E+08 L/kg.
The Koc for component 9 was estimated to be 5.78E+08 L/kg.
The Koc for component 10 was estimated to be 1.66E+08 L/kg.

Executive summary:

The Log soil adsorption coefficient (Log Koc) of the test material was estimated from the KOW. As the substance is a UVCB substance values were estimated on the representative structures of the ten main components of the test material.

The Koc for component 1 was estimated to be 2.04E+09 L/kg.

The Koc for component 2 was estimated to be 6.08E+05 L/kg.

The Koc for component 3 was estimated to be 1.66E+08 L/kg.

The Koc for component 4 was estimated to be 1.27E+08 L/kg.

The Koc for component 5 was estimated to be 2.04E+09 L/kg.

The Koc for component 6 was estimated to be 1.09E+11 L/kg.

The Koc for component 7 was estimated to be 3.08E+10 L/kg.

The Koc for component 8 was estimated to be 4.42E+08 L/kg.

The Koc for component 9 was estimated to be 5.78E+08 L/kg.

The Koc for component 10 was estimated to be 1.66E+08 L/kg.

Reference 3

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

17 September 2019 to 20 September 2019

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Unsuitable test system

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Version / remarks:

2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Version / remarks:

2001

Deviations:

no

GLP compliance:

no

Remarks:

Main study not conducted. Feasibility study only.

Type of method:

HPLC estimation method

Media:

other: HPLC screening method

Radiolabelling:

no

Test temperature:

30 °C

Details on study design: HPLC method:

The feasibility was carried out using the HPLC screening method.
The test system consisted of a high performance liquid chromatograph with appropriate detectors. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used. An injection of DDT was performed on the system to determine its retention time (24.1 minutes).
A solution of test material was prepared in methanol at 2.64 x 10^4 mg/L and was injected on the test system using unadjusted mobile phase (pH 5.6). Another solution of test material was prepared in methanol at 2.54 x 10^4 mg/L and was injected on the test system using the mobile phase adjusted to a pH of 3.1 using trifluoroacetic acid. The reason for using two pHs was because the test material contained amine functional groups which can form cations; cations are susceptible to secondary interactions with anionic silanol groups on the column. An acidic mobile phase neutralises these silanol groups and essentially prevents the secondary interactions; it also demonstrates if the secondary interactions were occurring in the unadjusted mobile phase giving rise to increased retention time.

The HPLC parameters used are as follow:
HPLC System: Agilent Technologies 1200, incorporating workstation and autosampler
Detector types: Variable wavelength (VW) evaporative light scattering (ELS)
Column: HSS Cyano 5 μ (150 x 4.6 mm id)
Column temperature: 30 °C
Mobile phase: Methanol:purified water (55:45 v/v)
pH of mobile phase: 5.6 and 3.1
Flow-rate: 1.0 mL/min
Injection volume: 10 μL
VW detector wavelength: 210 nm
ELS detector parameters:
nebuliser temperature: 40 °C
evaporator temperature: 80 °C
gas flow: 1.0 L/min
The mobile phase was ramped over 10 minutes to 100 % methanol shortly after the retention time of DDT in order to elute highly retained components of the test material.

Remarks on result:

not determinable

Remarks:

Definitive results for all the test material components would not be possible using the method guidelines.

Details on results (HPLC method):

The chromatography using the acidic mobile phase showed that the test material had components that eluted after the retention time of DDT by the methanol gradient. However, there wasn’t a significant group of peaks on the gradient with the unadjusted mobile phase; it was considered that components were retained beyond the runtime of the injection due to strong secondary interactions with the column. Even so, the chromatograms demonstrated that the adsorption coefficient of the test material would be a range with some of that range being greater than log Koc of 5.63. Definitive results for all the test material components would not be possible using the method guidelines.

Validity criteria fulfilled:

not applicable

Remarks:

Main study not conducted. Feasibility study only.

Conclusions:

Under the conditions of the study the chromatograms demonstrated that the adsorption coefficient of the test material would be a range with some of that range being greater than log Koc of 5.63. Definitive results for all the test material components would not be possible using the method guidelines.

Executive summary:

The adsorption coefficient of the test material was assessed according to OECD Test Guideline 121 and EU Method C.19. A feasibility was carried out using the HPLC screening method.

The test system consisted of a high performance liquid chromatograph with appropriate detectors. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used. An injection of DDT was performed on the system to determine its retention time (24.1 minutes).

A solution of test material was prepared in methanol at 2.64 x 10^4 mg/L and was injected on the test system using unadjusted mobile phase (pH 5.6). Another solution of test material was prepared in methanol at 2.54 x 10^4 mg/L and was injected on the test system using the mobile phase adjusted to a pH of 3.1 using trifluoroacetic acid. The reason for using two pHs was because the test material contained amine functional groups which can form cations; cations are susceptible to secondary interactions with anionic silanol groups on the column. An acidic mobile phase neutralises these silanol groups and essentially prevents the secondary interactions; it also demonstrates if the secondary interactions were occurring in the unadjusted mobile phase giving rise to increased retention time.

The chromatography using the acidic mobile phase showed that the test material had components that eluted after the retention time of DDT by the methanol gradient. However, there wasn’t a significant group of peaks on the gradient with the unadjusted mobile phase; it was considered that components were retained beyond the runtime of the injection due to strong secondary interactions with the column.

Under the conditions of the study the chromatograms demonstrated that the adsorption coefficient of the test material would be a range with some of that range being greater than log Koc of 5.63. Definitive results for all the test material components would not be possible using the method guidelines.

Description of key information

The test material was insoluble in all four organic solvent-water mixes, therefore the Log Koc of the test material was estimated from the Kow for risk assessment purposes whilst further testing is investigated.

As the substance is a UVCB substance values were estimated on the representatives tructures of the ten main components of the test material.

Fox (2019)

Under the conditions of the study the chromatograms demonstrated that the adsorption coefficient of the test material would be a range with some of that range being greater than log Koc of 5.63. Definitive results for all the test material components would not be possible using the method guidelines.

Additional information

Feierabend (2019)

The test material is a UVCB, therefore the determination of the Log Koc can only be carried out according to OECD guideline 121 and EU Method C19.

According to the guidelines, the test material should be dissolved in mobile phase methanol­water with a water content of at least 25 % for the determination of Log Pow. This is not possible because the test material precipitated in mobile phase methanol-water (75 % / 25 % and 55 % / 45 %). Even with the other solvents provided in the Guideline: acetonitrile, ethanol and isopropanol, no clear solution could be obtained after the addition of at least 25 % resp. 45 % water.

However, a clear solution could be obtained in pure methanol at a maximum concentration of 5 g/L in contrast to the solubility tests in pure acetonitrile in which the test material does not dissolve.

The test material was insoluble in all four organic solvent-water mixes, therefore a determination of the Log Koc is according to guideline technically not possible. Nevertheless, pre-tests with methanol solution in several concentrations were performed. Three different detectors (UV, ELSD and RI) were used, but no signals could be detected.

Weber and Jarvis (2019)

The Log soil adsorption coefficient (Log Koc) of the test material was estimated from the KOW.As the substance is a UVCB substance values were estimated on the representative structures of the ten main components of the test material.

The Koc for component 1 was estimated to be 2.04E+09 L/kg.

The Koc for component 2 was estimated to be 6.08E+05 L/kg.

The Koc for component 3 was estimated to be 1.66E+08 L/kg.

The Koc for component 4 was estimated to be 1.27E+08 L/kg.

The Koc for component 5 was estimated to be 2.04E+09 L/kg.

The Koc for component 6 was estimated to be 1.09E+11 L/kg.

The Koc for component 7 was estimated to be 3.08E+10 L/kg.

The Koc for component 8 was estimated to be 4.42E+08 L/kg.

The Koc for component 9 was estimated to be 5.78E+08 L/kg.

The Koc for component 10 was estimated to be 1.66E+08 L/kg.

Further testing will be undertaken to refine the values from the current estimates.

Fox (2019)

The adsorption coefficient of the test material was assessed according to OECD Test Guideline 121 and EU Method C. 19. A feasibility was carried out using the HPLC screening method.

The test system consisted of a high performance liquid chromatograph with appropriate detectors. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used. An injection of DDT was performed on the system to determine its retention time (24.1 minutes).

A solution of test material was prepared in methanol at 2.64 x 10^4 mg/L and was injected on the test system using unadjusted mobile phase (pH 5.6). Another solution of test material was prepared in methanol at 2.54 x 10^4 mg/L and was injected on the test system using the mobile phase adjusted to a pH of 3.1 using trifluoroacetic acid. The reason for using two pHs was because the test material contained amine functional groups which can form cations; cations are susceptible to secondary interactions with anionic silanol groups on the column. An acidic mobile phase neutralises these silanol groups and essentially prevents the secondary interactions; it also demonstrates if the secondary interactions were occurring in the unadjusted mobile phase giving rise to increased retention time.

The chromatography using the acidic mobile phase showed that the test material had components that eluted after the retention time of DDT by the methanol gradient. However, there wasn’t a significant group of peaks on the gradient with the unadjusted mobile phase; it was considered that components were retained beyond the runtime of the injection due to strong secondary interactions with the column.

Under the conditions of the study the chromatograms demonstrated that the adsorption coefficient of the test material would be a range with some of that range being greater than log Koc of 5.63. Definitive results for all the test material components would not be possible using the method guidelines.