1-O-β-(2 ,3-di-O-alka(e)noyl-6 -O-acetyl-D-mannopyranosyl)-D-erythritol

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 June 2019 to 07 June 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD Guideline 115: Surface Tension of Aqueous Solutions

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

other: EU Method A.5 Surface Tension

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of Inspection: 21 August 2018 Date of Issue: 19 November 2018

Type of method:

other: critical micelle concentration (CMC)

Remarks:

CMC is being used as a surrogate water solubility value as the test item is surface active

Key result

Water solubility:

5.15 mg/L

Conc. based on:

test mat.

Temp.:

20 °C

pH:

>= 4.7 - <= 6.1

Table 1

 

Concentration (mg/L)	Age of Solution (min)	Reading (mN/m)	Temperature (°C)
1.09 x 10^3	70	31.0	20.0
	73	31.0	20.0
	76	31.0	20.0
327	87	32.0	20.0
	91	31.5	20.0
	94	31.5	20.0
109	105	31.5	20.0
	108	32.0	20.0
	111	32.0	20.0
32.7	123	32.5	20.0
	126	32.0	20.0
	130	32.5	20.0
10.9	141	34.0	20.0
	144	33.5	20.0
	147	33.5	20.0
3.27	158	38.5	20.0
	161	38.0	20.0
	165	38.0	20.0
1.09	203	47.0	20.0
	207	47.5	20.0
	212	50.5	20.0
	216	53.0	20.0
	220	54.5	20.0
	223	56.0	20.0
	245	62.0	20.0
	249	62.0	20.0
	252	62.0	20.0
0.327	264	65.0	20.0
	267	64.5	20.0
	271	65.0	20.0
0.109	370	73.0	20.0
	373	72.5	20.0
	376	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

Concentration (mg/L)	Log10Concentration	Mean Surface Tension (mN/m)	Solution pH
1.09 x 10^3	3.04	31.0	4.7
327	2.51	31.7	5.7
109	2.04	31.8	6.1
32.7	1.51	32.3	6.0
10.9	1.04	33.7	5.9
3.27	0.514	38.2	5.6
1.09	0.037	62.0	5.6
0.327	-0.486	64.8	5.5
0.109	-0.963	72.7	5.6

The plot of log10[concentration(mg/L)] versus surface tension (mN/m) is shown in Figure 1, attached as an Illustration.

Line 1 (red) was generated from linear regression of 2 sample solution concentrations for which surface tension was shown to be concentration dependent and Line 2 (green) was generated from the linear regression of 4 sample solution concentrations for which the surface tension was observed to be essentially independent of concentration.

The intersection of these two lines gave the critical micelle concentration and was calculated by solving the two equations:

Line 1 equation: y = -26.6x + 51.873

Line 2 equation: y = -0.796x + 33.511

The sample solution at 10.9 mg/L was not used in generating the two lines. At this concentration the surface tension appeared to be transitioning to Line 2 at a shallower gradient than Line 1.

The sample solution at 0.109 mg/L was not used in generating the two lines. At this concentration the surface tension was only slightly affected and was approaching that of purified water.

It was decided to not use the 1.09 mg/L sample result in creating the concentration dependent line. Using all three results from the 3.27, 1.09 and 0.327 mg/L samples didn’t product a line with a satisfactory looking fit. Additionally, the 1.09 mg/L was the only sample that didn’t give consistent values in three measurements, requiring nine; this is an effect that is frequently seen when the surface tension becomes concentration dependent. Concentrations towards the ends of the concentration dependent line typical generate more consistent measurements. For these reason, the results from the 3.27 and 0.327 mg/L samples were considered more reliable.

The CMC was determined to be 5.15 mg/L.

Conclusions:

The critical micelle concentration of the test item was determined to be 5.15 mg/L at 20.0 ± 0.5°C.

Executive summary:

The critical micelle concentration of the test item has been determined to be 5.15 mg/L at 20.0 ± 0.5 °C, by determining the surface tension of a range of aqueous sample solutions of differing concentration, using a procedure based on Method A.5 Surface Tension of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 115 of the OECD Guidelines for Testing of Chemicals, 27 July 1995. As the surface tension test confirmed that the substance is a surfactant, traditional water solubility tests are not applicable. For surfactants, critical micelle concentration is considered an effective surrogate value for water solubility

Description of key information

Critical micelle concentration: 5.15 mg/L at 20°C; OECD 115; Fox, J. M. (2019)

Key value for chemical safety assessment

Water solubility:

5.15 mg/L

at the temperature of:

20 °C