Ammonium glycyrrhizate

Water solubility

Administrative data

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Due to surfactant properties of the test item, the water solubility could not be accurately determinated

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

Due to surfactant properties of the test item, the water solubility could not be accurately determinated

Principles of method if other than guideline:

Litterature references:
- KONDO, M. et al. Physicochemical properties and applications of a-and ß-glycyrrhizins, natural surface active agents in licorice root extract. J. Soc. Cosmet. Chem. 37, 177–189 (1986).
- Wang, Y. G., Dai, X. X., Shi, X. Y. & Qiao, Y. J. The simulation on self-aggregated glycyrrhizin structures. Int. J. Appl. Math. Stat. 50, 272–279 (2013).
- Matsuoka, K., Miyajima, R., Ishida, Y., Karasawa, S. & Yoshimura, T. Aggregate formation of glycyrrhizic acid. Colloids Surf. Physicochem. Eng. Asp. 500, 112–117 (2016).

GLP compliance:

yes

Type of method:

flask method

Test material

Test material information

Constituent 1

Reference substance name:

Ammonium glycyrrhizate

EC Number:

258-887-7

EC Name:

Ammonium glycyrrhizate

Cas Number:

53956-04-0

Molecular formula:

C42H65NO16

IUPAC Name:

ammonium glycyrrhizate

Results and discussion

Water solubility

Water solubility 1

Key result

Water solubility:

5 g/L

Temp.:

30 °C

pH:

>= 3.5 - <= 5

Remarks on result:

completely miscible

Remarks:

Due to surfactant properties of the test item, the water solubility could not be accurately determinated. See justification below.

Water solubility 2

Key result

Water solubility:

>= 0.16 - <= 4.4 g/L

pH:

<= 6

Remarks on result:

other: critical micelle concentrations (CMC) found in the literature, measured from the glycyrrhizic acid; temperature unknown

Any other information on results incl. tables

A preliminary test was carried out as a range finding test prior to the main test. The concentration range obtained gives an an approximate water solubility of 1.0 g/L. During the main test, the test item concentration at the end of the experiment was around 5 g/L, corresponding to the maximum reachable concentration (loading rate). All the introduced test item was therefore solubilized, the systems were not in the presence of an excess of test item anymore. The test item water solubility could not be determined due to the complete solubilisation of the test item.

These results are contradictory with those obtained during the preliminary test. However, an incubation step at 30°C for 24h was carried out during the main test whereas the mixture was shaken for 10 min at ambient temperature during the preliminary test. This longer incubation period may have allowed the formation of aggregates due to the physicochemical properties of the molecule.

Indeed, surfactant properties have been described in the literature for this test item (see section 4.10).

Applicant's summary and conclusion

Conclusions:

The water solubility of the test item could not be accurately determined according to the OECD method 105 due to surface-active properties.
The water solubility of this surfactant test item can be considered as its CMC (critical micelle concentration). Based on both the litterature and the experimental results, the CMC is considered to range 0.16 – 5 g/L depending on the pH of the solution.