1,3'-Bipyridinium, 5'-[[4-[[4-[(1',2'-dihydro-6'-hydroxy-3,4'-dimethyl-2'-oxo[1,3'-bipyridinium]-5'-yl)azo]benzoyl]amino]phenyl]azo]-1',2'-dihydro-6'-hydroxy-3,4'-dimethyl-2'-oxo-, salt with 2-hydroxypropanoic acid (1:2)

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February from 02nd to 06th, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Reason / purpose for cross-reference:

reference to other study

Remarks:

validated analytical method

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

adopted July 27, 1995

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Water solubility:

229 g/L

Conc. based on:

test mat.

Temp.:

20 °C

pH:

ca. 3.13

Details on results:

The measured concentrations are constant within ± 15 % and thus within the range required by the guidelines.

PRELIMINARY TEST
The water solubility of the test item was estimated to be ~130 g/l in a preliminary test and therefore the shake-flask method was used in the main test.

Results of the determination of test item concentrations

Sampling time	Measured concentration of test item (g/l )			Measured pH
	Test vessels	Mean with the 95% confidence intervals
After 24h	223	225 ± 14.6		3.14
	232			3.12
	222			3.13
After 48h	232	225 ± 13.8		3.13
	222			3.11
	222			3.11
After 72h	234	236 ± 3.7		3.12
	237			3.12
	237			3.12
Solubility of the test item (g/l)		229 ± 15.4	-
RSD%		3	-
pH of ultra-pure water		-	6.41

Conclusions:

Water solubility: 229 ± 15.4 g/l at 20  ± 1 °C and pH ca 3.13

Executive summary:

The water solubility of the test substance was determined by flask method, in accordance with the method and procedures outlined into the OECD guideline 105. The substance concentrations were determined by a previously validated analytical method. The substance was dissolved in water at a temperature somewhat above the test temperature; when saturation was achieved, the mixture was cooled and kept at the test temperature, stirring as long as necessary to reach equilibrium. Subsequently, the mass concentration of the substance in the aqueous solution was determined by HPLC-UV method.

The water solubility of the substance was determined to be 229 ± 15.4 g/l (95 % confidence interval)  at 20  ± 1 °C and pH ca 3.13. The measured concentrations are constant within ± 15 % and thus within the range required by the guidelines.

Conclusion

Water solubility: 229 ± 15.4 g/l at 20  ± 1 °C and pH ca 3.13

Description of key information

Water solubility: 229 ± 15.4 g/l at 20  ± 1 °C and pH ca 3.13

Key value for chemical safety assessment

Water solubility:

100 g/L

at the temperature of:

20 °C

Additional information

OECD 105 - flask method

The value for the chemical safety assessment was set to the maximum accepted value of 100 g/l.