Alcohols, C16-18 and ethoxylated C16-18 , phosphates (20 moles ethoxylation)

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 November 03, 2017 to February 09, 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 115: Surface Tension of Aqueous Solutions

Version / remarks:

27 July 1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EU Method A5: Surface tension

Version / remarks:

30 May 2008

Deviations:

no

Principles of method if other than guideline:

Below the CMC, a surfactant is considered to be thermodynamically soluble in the water; whereas above the CMC, the solubility of a surfactant in water has been exceeded and the excess surfactant aggregates to form micelles. These micelles have significantly less effect on the surface tension of a solution and are considered not to be in solution. Thus, the water solubility of a surfactant may be expressed in terms of the CMC.

GLP compliance:

no

Remarks:

The study was conducted in a facility which operates in accordance with Good Laboratory Practice principles; however no claim of GLP compliance was intended nor is made for this study

Type of method:

other: by determining the surface tension of a range of aqueous sample solutions of differing concentration

Key result

Water solubility:

< 1.7 mg/L

Conc. based on:

test mat.

Incubation duration:

ca. 15.75 h

Temp.:

20 °C

pH:

ca. 5.505

Remarks on result:

other: CMC - water solubility equivalent for surfactants; value rounded off to 7 mg/L

Details on results:

Please see below table.

Results

The readings and temperatures for the sample solutions are shown in the following table:

Table1: Surface tension values

Concentration (mg/L)	Reading (mN/m)	Temperature (°C)
1.068 x 10^3	40.5	20.0
	40.5	20.0
	40.5	20.0
320.4	41.5	20.0
	41.5	20.0
	41.5	20.0
106.8	43.5	20.0
	45.0	20.0
	45.5	20.0
	46.0	20.0
	46.0	20.0
	47.0	20.0
	47.0	20.0
	47.0	20.0
32.04	50.5	20.0
	50.5	20.0
	50.5	20.0
10.68	52.5	20.0
	52.5	20.0
	52.5	20.0
3.204	54.0	20.0
	55.5	20.0
	56.5	20.0
	57.0	20.0
	57.0	20.0
	58.0	20.0
	58.5	20.0
	58.5	20.0
	58.5	20.0
1.068	60.0	20.0
	60.0	20.0
	60.0	20.0
0.3204	70.0	20.0
	70.0	20.0
	70.0	20.0
0.1068	72.5	20.0
	72.5	20.0
	72.5	20.0

Mean surface tension values were based on the last three readings for a particular concentration which were considered to be constant.

The concentration (mg/L), log₁₀ [concentration (mg/L)] and mean surface tension values for the sample solutions are shown in the following table:

 

Table 2: The concentration (mg/L), log₁₀ [concentration (mg/L)] and mean surface tension values

Concentration (mg/L)	Log10Concentration	Mean Surface Tension (mN/m)	Solution pH
1.068 x 10^3	3.029	40.5	3.56
320.4	2.506	41.5	3.99
106.8	2.029	47.0	4.37
32.04	1.506	50.5	4.80
10.68	1.029	52.5	5.13
3.204	0.506	58.5	5.36
1.068	0.029	60.0	5.49
03204	-0.494	70.0	5.52
0.1068	-0.971	72.5	5.56

The plot of log₁₀ [concentration (mg/L)] versus surface tension (mN/m) was drafted. For graph, kindly refer the attached background material section.

The green line was generated from linear regression of 7 sample solution concentrations. The red line was not allocated any samples as there was no definitive CMC. However, there was a possibly event between 0.3 and 1.0 mg/L where the surface tension jumps by 10 mN/m and the largest step in half a log unit.

Considering this, the CMC was determined to be less than 1.07 mg/L.

Conclusions:

Under the study conditions, the the CMC or water solubility of the test substance was determined to be <1.7 mg/L at 20.0 ± 0.5°C.

Executive summary:

A study was conducted to determined the water solubility of the test substance based on critical micelle concentration (CMC), according to OECD Guideline 115 and EU Method A.5, in compliance with GLP. Due to the surface activity of the test substance, the CMC value was considered as a water soluibility equivalent in accordance with the ECHA R.7a Guidance.Under study conditions, the CMC of the test substance was determined to be <1.7 mg/L at 20.0 ± 0.5°C (Envigo, 2018).

Description of key information

The water solubility of the test substance was determined based on critical micelle concentration (a water solubility equivalent of surfactant), according to OECD Guideline 115 and EU Method A.5 (Envigo, 2018).

Key value for chemical safety assessment

Water solubility:

1.7 mg/L

at the temperature of:

20 °C

Additional information

(<1.7 mg/L, based on CMC)