(8α,9R,8'''α,9'''R)-1,1'-[(2,3,5,6-tetrafluoro-1,4-phenylene)bis(methylene)]bis(6'-methoxycinchonan-1-ium-9-ol) dibromide

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

Version / remarks:

1995

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

-0.257

Temp.:

20 °C

pH:

5

Key result

Type:

log Pow

Partition coefficient:

-0.277

Temp.:

20 °C

pH:

>= 7 - <= 7.1

Key result

Type:

log Pow

Partition coefficient:

1.14

Temp.:

20 °C

pH:

9.2

Details on results:

The increase in the partition coefficient value at pH 9 was attributed to a shift in hydrophilic / hydrophobic character of the test item following loss of protonation of the quinoline functional groups. The determined partition coefficients of the test item did not correlate entirely as expected from the dissociation constants, with the pH values. It is likely that the partitioning characteristics of the test item have been partially influenced by the necessary presence of other ions in the buffer solutions used to achieve and maintain the required, equilibrium pH values in the aqueous phases, as well as by the degree of dissociation of the acidic and basic functional groups.

Conclusions:

The log Kow of the substance at 20 °C has been found to be -0.257 at pH 5, -0.277 at pH 7 and 1.14 at pH 9.

Executive summary:

The n-octanol/water partition coefficient of the substance was studied under GLP to OECD TG 107, using the Flask Shake method. For the determination at each specified pH condition, citrate, phosphate and borate buffers solutions for pH 5, pH 7 and pH 9 were mutually saturated with n-octanol. Six partitions were performed for each pH value at a temperature ranging from 20.0 to 20.4 °C. In each test, the combined volume of both phases occupied not less than 90% of the total volume of the test vessel. Test substance aliquots of approximately 0.25 g were diluted in 250 mL of n-octanol saturated with the relevant pH buffer solution. The aqueous phase for the specific pH determinations was the relevant octanol-saturated buffer solution.

The required volumes of stock solution and aqueous phase were added to the vessels which were then equilibrated to the test temperature of 20 °C for a minimum of 1 hour before partitioning. The partitioning was performed by inversion of the flasks through approximately 180° over a five minute period. The test temperature was measured and confirmed at the time of partitioning and the flasks then returned to the 20 °C conditions to allow initial phase separation prior to decanting the individual phases for centrifugation.

Individual aliquots of each phase, from each vessel, were taken and phase isolation ensured by centrifugation at 13000 rpm, for 15 minutes. Aliquots of both phases, from each vessel and each stock solution were taken for analysis. The concentration of test item in the sample solutions was determined by high performance liquid chromatography (HPLC). The linearity over the relevant concentration range, specificity, precision and accuracy of the analytical method could be demonstrated.

The log Kow at 20 ± 0.5 °C has been determined to be -0.257 at pH 5, -0.277 at pH 7 and 1.14 at pH 9. The determined partition coefficients of the test item did not correlate entirely as expected from the dissociation constants, with the pH values. It is likely that the partitioning characteristics of the test item have been partially influenced by the necessary presence of other ions in the buffer solutions used to achieve and maintain the required, equilibrium pH values in the aqueous phases, as well as by the degree of dissociation of the acidic and basic functional groups.

Description of key information

log Kow = -0.257 at 20 °C and pH 5

log Kow = -0.277 at 20 °C and pH 7

log Kow = 1.14 at 20 °C and pH 9 (GLP, OECD TG 107)

Key value for chemical safety assessment

Log Kow (Log Pow):

-0.277

at the temperature of:

20 °C

Additional information

The increase in the partition coefficient value at pH 9 was attributed to a shift in hydrophilic / hydrophobic character of the test item following loss of protonation of the quinoline functional groups. The determined partition coefficients of the test item did not correlate entirely as expected from the dissociation constants, with the pH values. It is likely that the partitioning characteristics of the test item have been partially influenced by the necessary presence of other ions in the buffer solutions used to achieve and maintain the required, equilibrium pH values in the aqueous phases, as well as by the degree of dissociation of the acidic and basic functional groups.