Phosphoric acid, mono- and di-isotridecyl esters, compd. with 2,2'-iminobis[ethanol]

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 January 12, 2016 to February 11, 2016 and April 4, 2016 to April 29, 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

Principles of method if other than guideline:

As it was not possible to determine the water solubility of the test substance according to OECD 105, as an additional property to describe the solubility of the test substance in aqueous solution, the critical micelle concentration (cmc) of the test substance is determined in this study. The CMC was determined by concentration dependent measurement of the surface tension. Additionally, NMR spectrocsopic investigations were also carried out.

GLP compliance:

not specified

Type of method:

flask method

Specific details on test material used for the study:

Batch no.: RE 10-7
Appearance: paste-like

Key result

Water solubility:

ca. 402 000 mg/L

Conc. based on:

test mat.

Incubation duration:

24 h

Temp.:

22.4 °C

pH:

7.5

Remarks on result:

other: due to the formation of a gel, the investigation was stopped and the water solubility was approximated to 402000 mg/L. It was possible to create a gel with even higher concentrations of the test substance

Details on results:

With 6.7207 g of test substance being mixed into 10g of water, a gel with a total weight of 16.7207g was formed. This was equivalent to 40.2% (w/w) of test substance in solution/gel. Due to the fact that the density of the gel is not known and that the formation of the gel is a continuous process and no discrete point can be identified at which dissolution in water switches to gelling, the water solubility can only be approximated to 402000 mg/L. The pH value of a 10% solution of the test substance in water was 7.5 and the experiments were performed at 22.4°C.

Table 1: Amounts of test substance added to water

Experiment	Water [g]	Weighed sample [g]	Result
A	10.0	0.2615	slight cloudy
B	10.0	0.5564	moderately cloudy
c	10.0	1.0732	cloudy
D	10.0	2.6037	cloudy, viscous
E	10.0	3.6723	cloudy, viscous
F	10.0	5.0806	cloudy, viscous
G	10.0	6.7207	white gel

While being added to the water, solutions with increasing viscosity were being formed , finally resulting in a gel.

Conclusions:

Under the study conditions, the water solubility of the substance was determined to be 600 mg/L at 20°C.

Executive summary:

A study was conducted to determine the water solubility of the substance initially according to OECD Guideline 105 and later through critical micelle concentration measurements. As it was not possible to determine the water solubility of the test substance according to OECD 105 due to undissolved components, as an additional property to describe the solubility of the test substance in aqueous solution, the critical micelle concentration (CMC) of the test substance is determined in this study. The CMC was determined by concentration dependent measurement of the surface tension. Additionally, NMR spectrocsopic investigations were also carried out. From the concentration profile determined by surface tension measurements, it can be estimated that the CMC is reached at concentrations between 0.1 g/L to 1 g/L (for a more accurate evaluation plenty of more surface tensions at different concentrations are necessary). In order to obtain a more accurate estimation of the cmc, additional NMR relaxation measurements were carried out in the concentration range 0.1 -2.0 g/L. The NMR relaxation measurements indicate a CMC of 600 mg/L, this is consistent with the range estimated by the surface tension measurements. Under the study conditions, the water solubility of the substance was determined to be 600 mg/L at 20°C( Schwarzkopf, 2016 and Seiler, 2016).

Description of key information

The water solubility was determined initially according to OECD Guideline 107 and subsequently through determination of the critical micelle concentration (Schwarzkopf, 2016; Seiler, 2016). 

Key value for chemical safety assessment

Water solubility:

600 mg/L

at the temperature of:

20 °C