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Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

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 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EU Method A.24

Deviations:

no

GLP compliance:

not specified

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

Pow

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 Pow 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.

Conclusions:

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

Executive summary:

The test material is a UVCB, therefore the determination of the Log Pow can only be carried out according to OECD guideline 117 and EU Method A24.

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 Pow 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:

partition coefficient

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 octanol-water partition coefficient (log P) of the test material was estimated using the Log Octanol Water Partition Coefficient Program (KOWWIN version 1.68, US EPA).

GLP compliance:

no

Remarks:

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

Type of method:

calculation method (fragments)

Partition coefficient type:

octanol-water

Key result

Type:

log Pow

Partition coefficient:

15.477

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:

log Pow

Partition coefficient:

9.854

Remarks on result:

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

Key result

Type:

log Pow

Partition coefficient:

13.512

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:

log Pow

Partition coefficient:

13.297

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:

log Pow

Partition coefficient:

15.477

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:

log Pow

Partition coefficient:

18.717

Remarks on result:

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

Key result

Type:

log Pow

Partition coefficient:

17.734

Remarks on result:

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

Key result

Type:

log Pow

Partition coefficient:

14.279

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:

log Pow

Partition coefficient:

14.494

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:

log Pow

Partition coefficient:

13.512

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

Details on results:

As the test material is a UVCB substance composed of 10 main components a range of carbon chain lengths has been used to calculate the log P for the test material.
The log POW for component 1 was estimated to be 15.4766.
The log POW for component 2 was estimated to be 9.8536.
The log POW for component 3 was estimated to be 13.5122.
The log POW for component 4 was estimated to be 13.2972.
The log POW for component 5 was estimated to be 15.4766.
The log POW for component 6 was estimated to be 18.7166.
The log POW for component 7 was estimated to be 17.7344.
The log POW for component 8 was estimated to be 14.2794.
The log POW for component 9 was estimated to be 14.4944.
The log POW for component 10 was estimated to be 13.5122.
A median Log POW of 14 was considered representative for risk assessment purposes.

Conclusions:

As the test material is a UVCB substance composed of 10 main components a range of carbon chain lengths has been used to calculate the log P for the test material.
The log POW for component 1 was estimated to be 15.4766.
The log POW for component 2 was estimated to be 9.8536.
The log POW for component 3 was estimated to be 13.5122.
The log POW for component 4 was estimated to be 13.2972.
The log POW for component 5 was estimated to be 15.4766.
The log POW for component 6 was estimated to be 18.7166.
The log POW for component 7 was estimated to be 17.7344.
The log POW for component 8 was estimated to be 14.2794.
The log POW for component 9 was estimated to be 14.4944.
The log POW for component 10 was estimated to be 13.5122.
A median Log POW of 14 was considered representative for risk assessment purposes.

Executive summary:

The Log octanol-water partition coefficient (log P) of the test material was estimated using the Log Octanol Water Partition Coefficient Program (KOWWIN version 1.68, US EPA).

As the test material is a UVCB substance composed of 10 main components a range of carbon chain lengths has been used to calculate the log P for the test material.

The log POW for component 1 was estimated to be 15.4766.

The log POW for component 2 was estimated to be 9.8536.

The log POW for component 3 was estimated to be 13.5122.

The log POW for component 4 was estimated to be 13.2972.

The log POW for component 5 was estimated to be 15.4766.

The log POW for component 6 was estimated to be 18.7166.

The log POW for component 7 was estimated to be 17.7344.

The log POW for component 8 was estimated to be 14.2794.

The log POW for component 9 was estimated to be 14.4944.

The log POW for component 10 was estimated to be 13.5122.

A median Log POW of 14 was considered representative for risk assessment purposes.

Reference 3

Endpoint:

partition coefficient

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 A.8 (Partition Coefficient - HPLC Method)

Version / remarks:

2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Version / remarks:

2004

Deviations:

no

GLP compliance:

no

Remarks:

Main study not conducted. Feasibility study only.

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

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:

The chromatography showed that for both mobile phases the test material had components that eluted after the retention time of DDT by the methanol gradient. These peaks eluted more quickly with the acidic mobile phase and did not tail which suggested secondary interactions had occurred with the unadjusted mobile phase. Even so, the chromatograms demonstrated that the partition coefficient of the test material would be a range with some of that range being greater than log Pow of 6.5. Definitive results for all the test material components would not be possible using the method guidelines.

Conclusions:

Under the conditions of the study the chromatograms demonstrated that the partition coefficient of the test material would be a range, with some of that range being greater than log Pow of 6.5. Definitive results for all the test material components would not be possible using the method guidelines.

Executive summary:

The partition coefficient of the test material was assessed according to OECD Guideline117 and EU Method A.8. A feasibility study was carried out using the HPLC Method. As the test material was a complex mixture, the HPLC method would be the most appropriate method.

The test system consisted of a high performance liquid chromatograph with appropriate detectors. A reverse phase HPLC column with a very low percentage of polar groups was used and the mobile phase contained at least 25 % aqueous phase. An injection of DDT was performed on the system to determine its retention time (23.2 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 6.2) and the mobile phase adjusted to a pH of 3.0 using trifluoroacetic acid. The reason for using two pHs was because the test material contained amine functional groups which 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.

The chromatography showed that for both mobile phases the test material had components that eluted after the retention time of DDT by the methanol gradient. These peaks eluted more quickly with the acidic mobile phase and did not tail which suggested secondary interactions had occurred with the unadjusted mobile phase. 

Under the conditions of the study the chromatograms demonstrated that the partition coefficient of the test material would be a range, with some of that range being greater than log Pow of 6.5. 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 Log KOW values were estimated with KOWWIN ver. 1.69 for the structures of the UVCB substance for risk assessment purposes whilst further testing is investigated.

A median Log POW of 14.0 was considered representative for risk assessment purposes.

Fox (2019)

Under the conditions of the study the chromatograms demonstrated that the partition coefficient of the test material would be a range, with some of that range being greater than log Pow of 6.5. Definitive results for all the test material components would not be possible using the method guidelines.

Key value for chemical safety assessment

Log Kow (Log Pow):

14

Additional information

Feierabend (2019)

The test material is a UVCB, therefore the determination of the Log Pow can only be carried out according to OECD guideline 117 and EU Method A24.

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 Pow 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 octanol-water partition coefficient (log P) of the test material was estimated using the Log Octanol Water Partition Coefficient Program (KOWWIN version 1.68, US EPA).

As the test material is a UVCB substance composed of 10 main components a range of carbon chain lengths has been used to calculate the log P for the test material.

The log POW for component 1 was estimated to be 15.4766.

The log POW for component 2 was estimated to be 9.8536.

The log POW for component 3 was estimated to be 13.5122.

The log POW for component 4 was estimated to be 13.2972.

The log POW for component 5 was estimated to be 15.4766.

The log POW for component 6 was estimated to be 18.7166.

The log POW for component 7 was estimated to be 17.7344.

The log POW for component 8 was estimated to be 14.2794.

The log POW for component 9 was estimated to be 14.4944.

The log POW for component 10 was estimated to be 13.5122.

A median Log POW of 14.0 was considered representative for risk assessment purposes.

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

Fox (2019)

The partition coefficient of the test material was assessed according to OECD Guideline117 and EU Method A.8. A feasibility study was carried out using the HPLC Method. As the test material was a complex mixture, the HPLC method would be the most appropriate method.

The test system consisted of a high performance liquid chromatograph with appropriate detectors. A reverse phase HPLC column with a very low percentage of polar groups was used and the mobile phase contained at least 25 % aqueous phase. An injection of DDT was performed on the system to determine its retention time (23.2 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 6.2) and the mobile phase adjusted to a pH of 3.0 using trifluoroacetic acid. The reason for using two pHs was because the test material contained amine functional groups which 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.

The chromatography showed that for both mobile phases the test material had components that eluted after the retention time of DDT by the methanol gradient. These peaks eluted more quickly with the acidic mobile phase and did not tail which suggested secondary interactions had occurred with the unadjusted mobile phase. 

Under the conditions of the study the chromatograms demonstrated that the partition coefficient of the test material would be a range, with some of that range being greater than log Pow of 6.5. Definitive results for all the test material components would not be possible using the method guidelines.