Bis[N-(4-{[4-(diethylamino)phenyl][4-(ethylamino)-1-naphthyl]methylene}cyclohexa-2,5-dien-1-ylidene)-N-ethylethanaminium] [mono and bis(dodecanyl, branched)]-(sulfonatophenoxy) benzenesulfonate

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Measure by spectrophotometry of the test item dissolved in water

GLP compliance:

no

Type of method:

other: spectrophotometry

Water solubility:

ca. 0 mg/L

Conc. based on:

other: basic compound C+

Loading of aqueous phase:

1 other: g

Temp.:

22 °C

Remarks on result:

other: there is no peak of absorbance, i.e. no dissolved test item was detected

Remarks:

1st Filtration (0.45 µm)

Water solubility:

ca. 0.018 mg/L

Conc. based on:

other: basic compound C+

Loading of aqueous phase:

2 other: g

Temp.:

22 °C

Remarks on result:

other: pH not determined

Remarks:

1st Filtration (0.45 µm)

Water solubility:

ca. 0.125 mg/L

Conc. based on:

other: basic compound C+

Loading of aqueous phase:

4 other: g

Temp.:

22 °C

Remarks on result:

other: pH not determined

Remarks:

1st Filtration (0.45 µm)

Key result

Water solubility:

< 0.007 mg/L

Conc. based on:

test mat. (dissolved fraction)

Temp.:

22 °C

Remarks on result:

other: ph not determined

Remarks:

Solubility calculated based on the limit of detection of the method

Details on results:

The key result is the concentration of the substance calculated after the second filtration of the filtrates, and considering the limit of detection of the method, since no BB7 was detected.

Calculated concentrations from standard B using a 0.45 µm filter

		Test 1 g of blue 85-219	Test 2 g of blue 85-219	Test 4 g of blue 85-219
Visual observation of the aqueous filtrate		Slight bluish reflections	Slight blue tint	Light blue
Filtration		0.45 µm porosity	0.45 µm porosity	0.45 µm porosity
Dilution numbers		2	2	2
Measured OD   (Cary 60 AGILENT)	A-	DO 239 nm = 0.0313 u.Abs	DO 239 nm = 0.0616 u.Abs	DO 239 nm = 0.1119 u.Abs
	C+	DO 611 nm = -0.0042u.Abs	DO 611 nm = 0.0016u.Abs	DO 611 nm = 0.0115u.Abs
Concentrations of reference  (Standard B)	A-	0.2245 mg/l
	C+	0.4105 mg/l
OD of reference (Standard B)	A-	DO 239 nm = 0.0189
	C+	DO 611 nm = 0.07124
Calculated concentrations (mass ratio)	A-	CA-= 0.74 mg/l (100%)	CA-= 1.46 mg/l (99%)	CA-= 2.66 mg/l (95%)
	C+	Nul (0%)	CC+ = 0.018 mg/l (1%)	CC+  = 0.13 mg/l (5%)

Calculated concentration from Standard C using a 0.45 µm filter

		Test 1 g of blue 85-219	Test 2 g of blue 85-219	Test 4 g of blue 85-219
Visual observation of the aqueous filtrate		Slight bluish reflections	Slight blue tint	Light blue
Filtration		0.45 µm porosity	0.45 µm porosity	0.45 µm porosity
Dilution numbers		2	2	2
Measured OD   (Cary 60 AGILENT)	A-	DO 239 nm = 0.0313 u.Abs	DO 239 nm = 0.0616 u.Abs	DO 239 nm = 0.1119 u.Abs
	C+	DO 611 nm = -0.0042u.Abs	DO 611 nm = 0.0016u.Abs	DO 611 nm = 0.0115u.Abs
Concentrations of reference  (Standard C)	A-	0.5631 mg/l
	C+	0.0.8434 mg/l
OD of reference (Standard C)	A-	DO 239 nm = 0.0463
	C+	DO 611 nm = 0.1568
Calculated concentrations (mass ratio)	A-	CA-= 0.74 mg/l (100 %)	CA-= 1.46 mg/l (99%)	CA-=  2.66 mg/l (96%)
	C+	Nul (0%)	CC+ = 0.018 mg/l (1%)	CC+ = 0.13 mg/l (4%)

Conclusions:

In the test 1 g of Blue 85-219, the anionic compound A- is the only substance present in the aqueous filtrate.
In the extracts of the tests 2 and 4 g of Blue 85-219, both the anionic compound A- and the basic compound C+ are identified but in proportions different than in Blue 85-219.
In the 3 extracts, the concentration of the anionic compound A- is significantly higher than the one of the basic compound C+.

Therefore, Blue 85-219 batch 900501 used to perform the analyses contains the anionic compound A- as impurity which has been solubilized in water.

Traces of the basic compound found in the aqueous extracts may come from fine particles that have passed through the filter and then solubilized by methanol. Therefore, the filtrates were filtrated a second time with a 0.20 µm filter. At the visual observation of the filters, it was show that the more the substance was added, the more fine particles are found.

After dilution in methanol, the spectrophotometry analysis did not detect the basic compound (no peak of absorbance), meaning that the solubility of the substance is zero.

Based on a worst case scenario, the solubility of the substance was calculated considering the limit of detection of the method.

Reference 2

Endpoint:

water solubility

Remarks:

Shake flask method

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 2021-02-26 to 2021-04-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Key result

Water solubility:

ca. 7.27 µg/L

Conc. based on:

test mat.

Incubation duration:

ca. 72 h

Temp.:

20 °C

pH:

ca. 7

Water solubility:

ca. 5.78 µg/L

Conc. based on:

test mat.

Incubation duration:

ca. 72 h

Temp.:

40 °C

pH:

ca. 7

Water solubility:

ca. 460 µg/L

Conc. based on:

test mat.

Incubation duration:

ca. 72 h

Temp.:

20 °C

pH:

ca. 3

Water solubility:

ca. 983 µg/L

Conc. based on:

test mat.

Incubation duration:

ca. 72 h

Temp.:

40 °C

pH:

ca. 3

Water solubility:

ca. 2.54 µg/L

Conc. based on:

test mat.

Incubation duration:

ca. 72 h

Temp.:

20 °C

pH:

ca. 10

Water solubility:

ca. 7.25 µg/L

Conc. based on:

test mat.

Incubation duration:

ca. 72 h

Temp.:

40 °C

pH:

ca. 10

Details on results:

The results, obtained from this study, showed relatively high deviations between samplings and replicates, but are assumed to be the best obtainable outcome for this test item and are therefore accepted.
This is confirmed by the inconsistent solubility trials performed before. As the values for higher incubation times between the respective replicates do not show more homogenous results compared to lower times, it can be assumed that even a longer incubation time would not lead to more reliable results.

The solubility of the test item was determined a based on the two test item compounds C+ (cationic) and A- (anionic).
The validity criterion regarding the repeatability could only be met for pH 7 and 10 at 40 °C for C+ and for pH 3 at 40 °C for A-.

The solubility tendency was higher for higher temperatures, the cationic compound (C+) showed a higher solubility in acidic medium (buffer pH 3) and the acidic compound (A-) a higher solubility in basic medium (pH 10).
Nevertheless, the observed concentrations of the anionic coumpound A- demonstrate, that this component was leached from the test item, indicating that the anionic compound A- is present in excess.

In order to estimate the solubility of the test item, a stoichiometric calculation was performed on basis of the cationic coumpond C+ as the relevant analyte.
Due to the excess of the anionic coumpound A- within the test item, this component was not taken into account for this calculation.

Conclusions:

The water solubility of the test item (calculated from the measured concentration of the cationic compound of the test item) are the following:
- pH 3 - 20°C = 460 µg/L
- pH 3 - 40°C = 983 µg/L
- pH 7 - 20°C = 7.27 µg/L
- pH 7 - 40°C = 5.78 µg/L
- pH 10 - 20°C = 2.54 µg/L
- pH 10 - 40°C = 7.25 µg/L

Executive summary:

The water solubility of the Test Item in dependence of the pH and temperature was determined according to OECD guideline 105 (1995) and Council Regulation (EC) No. 260/2014, Method A.6 from 2021-02-26 to 2021-04-28 at the test facility.

 

In forefront to this study, multiple preliminary tests and inconsistent solubility trials were performed. Within these experiments, it was observed that the test item has a complex and difficult to predict solubility behaviour.

The main observation was, that the test item has a high tendency to form stable colloidal dispersions, even in buffer solutions and pure water. This dispersions were also eluted from a column elution setup, making this test design infeasible. Finally, the only way to remove the colloidal dispersed material was to filtrate the samples through 0.2 µm PTFE membrane filters. As adsorption to this filter material was checked negative, this procedure was deemed acceptable.

The results, obtained from this study, showed relatively high deviations between samplings and replicates, but are assumed to be the best obtainable outcome for this test item and therefore accepted.

 

The solubility of the test item was determined using the flask method at 20 ± 0.5 °C with pre-incubation at 30 ± 0.5 °C and at 40 ± 0.5 °C with pre-incubation at 50 ± 0.5 °C for pH values of 3, 7 and 10, respectively.

The analytical methods (LC-MS/MS and HPLC-DAD, external standard calibration) for the determination of the 2 test item components were validated and tested with satisfactory results in regard to linearity, accuracy, precision and specificity for each test system and each component / analytical standard, respectively.

 

The summarized results of the water solubility in mg/L of the test item and of its two test item components are given below:

 

	Test Item (based on the basic compound C+)
	pH 3	pH 7	pH 10
20°C	0.460	0.00727	0.00254
40°C	0.983	0.00578	0.00725
	Cationic compound of the Test Item (C+)
	pH 3	pH 7	pH 10
20°C	0.159	0.00252	0.000879*
40°C	0.340	0.00200	0.00251
	Anionic compound of the Test Item (A-)
	pH 3	pH 7	pH 10
20°C	3.20*	0.855*	3.91*
40°C	2.20*	4.05*	24.2

* Value below the respective LOQ

Description of key information

Water solubility of the Substance at 20°C, pH 7 according to the test performed according to the guideline OECD 105

Key value for chemical safety assessment

Water solubility:

0.007 mg/L

at the temperature of:

20 °C