(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

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

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 105 (Water Solubility)

Version / remarks:

1995

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Key result

Water solubility:

2.42 g/L

Conc. based on:

test mat.

Incubation duration:

>= 24 - <= 72 h

Temp.:

20 °C

pH:

>= 7.5 - <= 7.7

Remarks on result:

other: Unmodified, purified water

Key result

Water solubility:

0.64 g/L

Conc. based on:

test mat.

Incubation duration:

>= 24 - <= 72 h

Temp.:

20 °C

pH:

>= 5 - <= 5.1

Remarks on result:

other: pH 5 buffer solution

Key result

Water solubility:

2.88 g/L

Conc. based on:

test mat.

Incubation duration:

>= 24 - <= 72 h

Temp.:

20 °C

pH:

>= 7.1 - <= 7.2

Remarks on result:

other: pH 7 buffer solution

Key result

Water solubility:

0.924 g/L

Conc. based on:

test mat.

Incubation duration:

>= 24 - <= 72 h

Temp.:

20 K

pH:

9.3

Remarks on result:

other: pH 9 buffer solution

Details on results:

The determined water solubility of the test item did not correlate entirely as expected from the dissociation constants, with the pH values.
It is likely that the solubility of the test item has 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 sample solutions, as well as by the degree of dissociation of the acidic and basic functional groups.

Conclusions:

The solubility of the substance in water was determined to be 2.42 g/L at 20 °C in unmodified, purified water.

Executive summary:

The water solubility of the test substance was determined under GLP to OECD TG 105, using the flask method. The test was conducted using unmodified, purified water and specifically prepared buffer solutions to simulate different pH conditions. The pH 5 buffer solution was composed of 0.029 M sodium citrate and 0.021 M citric acid, the pH 7 buffer solution was composed of 0.03 M disodium hydrogen orthophosphate (anhydrous), 0.02 M potassium dihydrogen orthophosphate and 0.02 M sodium chloride, and the pH 9 buffer solution was composed of 0.01 M disodium tetraborate and 0.02 M sodium chloride. The water solubility was determined in preliminary tests by visual and analytical assessments. Based on these assessments, a definitive test was conducted with sets of three separate flasks with unmodified, purified water, and pH 5, pH 7 and pH 9 buffer solutions. Adequate aliquots of test substance were weighed into test flasks and 50 mL of water or buffer solution were added. Flasks were then shaken at 30 °C for a period of 24, 48 or 72 hours. Each flask was re-equilibrated at 20 °C for a period of 24 hours, with intermittent swirling. The contents wee then centrifuged at 13000 rpm for 15 minutes and supernatants isolated excluding excess, undissolved test substance. Filtration of the unmodified water and pH 7 and pH 9 buffered sample solutions with PES 0.2 μm was also required to eliminate suspended material prior to diluting for analysis. The pH value of each solution was measured. The concentration of the substance in the sample solutions was determined by an appropriate high performance liquid chromatography method. The linearity of the detector response over the relevant concentration range was satisfactory for all standard solutions with a first order correlation coefficient ranging from 0.9991 to 1.0000. The specificity of the analytical method was confirmed as the UV spectra obtained with a diode array detector were consistent between all standard and sample solutions. The precision of the method was addressed from the relative standard deviation from the mean calculated for the three individual samples analysed under each test condition, which were 1.03, 3.25, 0.679 and 2.4% for measurements made for unmodified water and pH 5, pH 7 and pH 9 buffered solutions. The results of each definitive test also satisfied the guideline quality criteria of less than 15% variance between the individual concentrations of the three samples with different initial saturation periods. The accuracy of the test method was not determined as no extraction techniques were required. The solubility of the test substance at 20 °C was determined to be 2.42 g/L in unmodified, purified water and 0.64 g/L at pH 5, 2.88 g/L at pH 7 and 0.924 g/L at pH 9. The determined water solubility of the test item did not correlate entirely as expected from the dissociation constants, with the pH values. It is likely that the solubility of the test item has 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 sample solutions, as well as by the degree of dissociation of the acidic and basic functional groups.

Description of key information

Water solubility = 2.42 g/L at 20 °C (GLP, OECT TG 105)

Key value for chemical safety assessment

Water solubility:

2.42 g/L

at the temperature of:

20 °C

Additional information

The determined water solubility of the test item did not correlate entirely as expected from the dissociation constants, with the pH values. It is likely that the solubility of the test item has 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 sample solutions, as well as by the degree of dissociation of the acidic and basic functional groups.