2,2'-azobis[2-methylpropionamidine] dihydrochloride

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30.07.-08.08.2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Water solubility:

> 168.05 - < 188.5 g/L

Temp.:

20 °C

pH:

> 5.57 - < 6.55

Remarks on result:

other: based on individual measurements

Key result

Water solubility:

ca. 176.2 g/L

Temp.:

20 °C

Remarks on result:

other: mean

Measurements for Temperature Dependency of Water Solubility

The data which was acquired for temperature dependency of water solubility is presented in the following table:

Flask	Temperature in °C	Test item conc. (diluted sample) in mg/L	Dilution factor	Test item Conc. (original sample) in g/L	Difference to previous sample % / °C
1	20	204.5	1000	204.5
2	5	168.7	1000	168.7	1.2

Because the difference between the measured concentrations of the two flasks was < 3 % / °C (1.2 % / °C), the main study was performed at 20 °C only.

Measurements during Equilibration

the data which was acquired during equilibration time (flask 1) is presented in the following table:

Day	Temperature in °C	pH*	Test item conc. (diluted sample) in mg/L	Dilution factor	Test item conc. (original sample) in g/L	Difference to previous sample %
1	20.3	6 -7	206.61	1000	206.61	--
2	20.1	6-7	187.43	1000	187.43	-9.3
5	20.5	6 -7	191.04	1000	191.04	1.9
6	20.3	6 -7	171.47	1000	171.47	-10.2

After the analysis of the sample of day 10, the plateau was considered as reached.

Measurements at Plateau, Result

The concentrations of test item were determined from the measured values following the equation (y=0.1082*x-0.0478). The following table gives the values which were measured at the plateau. A standard deviation of 7.6 g/L was calculated giving a relative standard deviation of 4.3 %.

Flask	1	2	3	4	5	6
pH	5.57	6.55	6.14	6.28	6.33	6.13
Measured values (Area in mAU*min)	18.5023	17.4944	19.1901	19.3993	18.3957	20.4564
Concentration test item in mg/L (diluted sample)	171.45	168.05	178.50	179.85	170.90	188.50
Dilution factor	1000	1000	1000	1000	1000	1000
Concentration test item in g/L (original sample)	171.45	168.05	178.50	179.85	170.90	188.50

Temperature was measured with 19.5 - 20.3 °C.

Mean at the plateau is 176.2 ± 7.6 g/L

Conclusions:

Interpretation of results (migrated information): very soluble (> 10000 mg/L)
The water solubility of 2,2'-azobis[2-methylpropionamidine] dihydrochloride is determined by the flask method to be 176.2 g/L.

Executive summary:

The solubility of 2,2'-azobis(2 -amidinopropane)dihydrochloride in water was determined from the measured concentrations of test item in the filtrated and diluted test solutions.

In a preliminary study, solubility of the test item in water was estimated as approx. 200 g/L. The flask method was used for the determination of the solubility of the test item in water. In the main study, 50 - 85 g test item were weighed into each of six individual vessels, water was added, and the vessels were shaken at 20.0 ± 0.5 °C.

In several steps, additional volumes of water were added, with total volumes ranging from 100 - 150 mL, because of the high viscosity of the mixtures. The additions resulted in loading rates of 500 - 727 g/L. On days 2, 5, and 6, vessel 1 was taken from the shaking apparatus and storred at 20.0 ± 0.5 °C for equilibration. Samples were taken, filtrated, diluted and analysed using HPLC as shaking of the test vessels was continued.

No differences above 15 % in the concentration of the solution could be determined between the sampling dates 5 and 6, supporting the hypothesis, that the maximum concentration of the test item had been reached. Therefore, on day 6, vessels 2 - 6 were sampled and analysed. Dependency of the solubility on amount of the test item (nominal load) was not perceived.

At the plateau, the concentration of 2,2'-azobis(2 -amidinopropane)dihydrochloride in water had reached 176.2 ± 7.6 g/L at 20.0 ± 0.5 °C.

Description of key information

The water solubility of 2,2'-azobis[2-methylpropionamidine] dihydrochloride is determined by the flask method to be 176.2 g/L.

Key value for chemical safety assessment

Water solubility:

176.2 g/L

at the temperature of:

20 °C