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Physical & Chemical properties

Water solubility

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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:
OECD Guideline 105 (Water Solubility)
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
GLP compliance:
yes (incl. certificate)
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   
 2 168.7  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
 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

Additional information