Pentasodium 2,2'-((2,4-diamino-5-(4-methoxy-2-sulfophenylazo)-1,3-phenylene)bis(azo))bis(5-(2-(sulfonatooxyethyl)sulfonyl)benzenesulfonate

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From June 19, 2006 to June 26, 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Key result

Water solubility:

66.3 g/L

Conc. based on:

act. ingr.

Loading of aqueous phase:

10 000 g/L

Incubation duration:

24 h

Temp.:

20 °C

Remarks on result:

other: pH not determined

Water solubility:

145.8 g/L

Conc. based on:

test mat.

Loading of aqueous phase:

10 000 g/L

Incubation duration:

24 h

Temp.:

20 °C

Remarks on result:

other: pH not determined

Preliminary Visual Estimation of the Water Solubility and stirring test

Increasing water amounts were added stepwise to about 98 mg of the test substance.

Table: Appearance of the test mixtures

Amount of the test substance in mg	Total volume in mL	Appearance of mixture
98.4	0.1	Undissolved
	0.5	Dissolved

 

The preliminary visual experiments showed that the water solubility of the test substance was between 196.8 and 984 g/L.Therefore, the water solubility was determined by the "flask-method".

 

Table: Stirring test

 

Amount of the test substance in g	Total volume in mL	Appearance of mixture
3.01	10	could be stirred
4.01	10	could be stirred
5.02	10	could be stirred
5.99	10	could be stirred
7.99	10	could be stirred
10.03	10	could be stirred, clear solid fraction
12.04	10	could not be stirred
13.79	10	could not be stirred
16.01	10	could not be stirred

 

The stirring tests showed that up to 1000 g/L test substance can be used for the flask method.

 

Flask-Method

 

Table: Water solubility of the test item - experiments A to D

 

Experiment	A	B	C	D (blank)
Amount of test substance (g)	10.05	10.01	10.22	-
Stirring time at 30°C (h)	24	48	72	72
pH at 27°C	4.7	4.7	4.7	6.9
Aliquot of the flasks (g)	0.61	0.61	0.61	0.5 mL
End weight (g)	50.16	50.28	50.27	50
Aliquot of the dilutions (mL)	0.25	0.25	0.25	0.25
End volume (mL)	1	1	1	1
Measured concentration (mg/L)	442.3    1437.0	437.3    1439.5	453.0   1454.7	-
Mean concentration (mg/L)	439.6	438.4	453.9	-
Water solubility (g/L)	144.5	144.6	148.4	-

 

Average experiments A to C (without correction for the purity): 145.8 g/L

Standard deviation: 2.3 g/L

Relative standard deviation: 1.5%

 

Concentrations of standards for recheck

 

Standard	Measured concentration (g/L)	% Recovery
Standard E (c=1.09 g/L)	1.08/1.09	99.8
Standard F (c=0.53g/L)	0.52/0.52	97.4

 

Recoveries of the 'Recheck sample' ranged from 97.4% to 99.8%, indicating a good accuracy of the analytical method.

Conclusions:

Very soluble (> 10000 mg/L)
Under the study conditions, the water solubility of the test substance at a temperature of 20°C was determined to be 145.8 g/L (RSD 1.5%, without correction for the purity).

Executive summary:

A study was conducted to determine the water solubility of the test substance, according to the OECD Guideline 105 and EU Method A.6, in compliance with GLP.

 

Preliminary visual estimation of water solubility was performed with increasing water amounts. Because of the high water solubility of the test substance, additional stirring tests were performed at 20°C with different amounts of the test substance and 10 mL distilled water. For the main test, three flasks were prepared with about 10 g of the homogenised test substance and 10 mL distilled water. The batches were stirred for different times at 30°C (experiment C for 72 h, experiment B for 48 h, experiment A for 24 h) in tightly closed flasks. After equilibration for 24 h at 20°C, aliquots of the saturated aqueous phase were taken and centrifuged (30 minutes, 20°C, 15000 rpm). Aliquots of the aqueous phases were filtered through two 0.2 µm membrane filters and diluted with eluent at the start of elution:

Dilution of flask A: 0.61 g (flask A) + 49.55 g eluent,

Dilution of flask B: 0.61 g (flask B) + 49.67 g eluent,

Dilution of flask C: 0.61 g (flask C) + 49.66 g eluent.

The concentration of the test substance was determined by HPLC. Another experiment was performed according to this procedure but without test substance ("blank"= D)

 

Under the study conditions, the water solubility of the test substance at a temperature of 20°C was determined to be 145.8 g/L (RSD 1.5%, without correction for the purity).

Description of key information

The water solubility of the test substance at a temperature of 20°C was determined to be 145.8 g/L (RSD 1.5%, without correction for the purity).

This calculates to 66.3 g/L for the active ingredient.

Key value for chemical safety assessment

Water solubility:

66.3 g/L

at the temperature of:

20 °C