Sophorolipids: fermentation products of glucose and fatty acids, C18 (unsaturated), glycerol esters with yeast Candida Bombicola, partially hydrolysed

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

in March 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

For the cmc measurement no guideline could be identified. Yet for the actual study, measurement is documented with raw data (including diagrams), identification of equipment, description of measurement process, summary, identification of test substance. As a consequence the study and its documentation is sufficiently trustworthy to be used for risk assessment.

Qualifier:

equivalent or similar to guideline

Guideline:

other: accepted scientific principle

Principles of method if other than guideline:

The critical micelle concentration (cmc) was examined using tensiometry which represents an accepted scientific method. The surface tension of a surfactant solution does no longer change at the onset of cmc formation.

GLP compliance:

no

Type of method:

other: The cmc was determined using a tensiometer by plotting surface tension (mN/m) against concentration of the test item in solution (%). The cmc is regarded the relevant parameter for water solubility of surfactants.

Key result

Water solubility:

>= 0.2 - <= 0.4 g/L

Conc. based on:

act. ingr.

Remarks on result:

other: critical micelle concentration

Remarks:

Temperature and pH not reported

Details on results:

The cmc of Sophorlipids is 0.02 – 0.04 % (active matter). Based on the assumption the density of the solution is 1 kg/L, this leads to a maximum solubility of Sophorolipids in water of 0.2 – 0.4 g/L.

Surface tension of test item solutions at different concentrations
Concentration (% active matter)	Surface tension (mN/m)
0.002	48
0.004	45
0.01	40
0.02	39
0.04	38
0.2	38
0.4	38
0.5	37

Conclusions:

The critical micelle concentration (CMC) of the test item was determined to be 0.2 to 0.4 g/L.

Executive summary:

In this study, the critical micelle concentration (cmc) of Sophorolipids: fermentation products of glucose and fatty acids, C18 (unsaturated), glycerol esters with yeast Candida, partially hydrolysed, was determined with a tensiometer by plotting surface tension (mN/m) against concentration of the test item in solution (%).

As a surfactant, the maximum solubility of Sophorolipids in water is derived from the critical micellar concentration. The cmc of Sophorolipids is 0.02 – 0.04 % (active matter). Based on the assumption the density of the solution is 1 kg/L, this leads to a maximum solubility of Sophorolipids in water of 0.2 – 0.4 g/L.

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

unknown

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

adopted on 27 July 1995

Deviations:

yes

Remarks:

Guideline study with modifications.

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

Guideline study with modifications.

GLP compliance:

no

Type of method:

flask method

Key result

Water solubility:

>= 147 g/L

Temp.:

23 °C

pH:

5.3

Sample no.	Amount of sample [g]	Amount of test item [g]	Filled up with water to [mL]	Test concentration [g/L]	Visual observations	pH value^1
1	2.017	0.734	5	147	clear sample	5.3

¹: The original sample had a pH value of 5.4

Conclusions:

The test item remained clear when diluted with water. Consequently a water solubility of the test item can be defined as ≥ 147 g/L.

Executive summary:

The solubility of the filtrated substance in water was determined according to OECD guidline 105 (adopted on 27 July 1995) with the flask method (modified) at 23 °C. The water solubility was checked visually. A value of >= 147 g/L was determined. It could be concluded that under the conditions of the test the substance was completely miscible with water.

Reference 3

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2015-03-09 to 2015-03-17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

adopted on 27 July 1995

Deviations:

yes

Remarks:

Guideline study with modifications.

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

30 May 2008

Deviations:

yes

Remarks:

Guideline study with modifications.

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Remarks:

modified

Conc. based on:

test mat.

Temp.:

24.7 °C

pH:

ca. 5.2

Remarks on result:

not determinable

Remarks:

The unfiltrated test substance is not completely miscible with water under the given conditions.

Details on results:

At the two tested concentrations of 94.2 g/L and 188.4 g/L, opalescent floating particles could be observed. They could be separated by filtration (syringe filter, nylon (PA), 0.20 µm; light blue). The resulting solutions were completely clear. It could be assumed that the test item contains insoluble as well as good water-soluble components. The results showed that the test item was in the tested concentrations and under the conditions of the test not completely miscible with water. For details please see table 1 in section “any other details on results incl. tables”.

Table 1: Results

Sample No.	Amount of test item [mL]	Filled up with water to [mL]	Test concentration [g/L]	Visual observations	pH value (1)
1	2	10	94,2	Sample not clear; opalescent floating particles	5.23
2	4	10	188.4	Sample not clear; opalescent floating particles	5.22

(1) The purified water used for the tests had a pH value of 7.27, the original test item pH 5.31. Calculated with the density of the test item (determined by weighing of defined volumes): 471 mg/mL (in relation to water-free substance)

In both samples opalescent floating particles could be observed. They could be separated by filtration (syringe filter, nylon (PA), 0.20 um; light blue). The resulting solutions were completely clear.

Conclusions:

Under the given conditions, the unfiltrated test substance was not completely miscible with water.

Executive summary:

The water solubility of the test item was determined according to OECD Guideline 105 [adopted on 27 July 1995] and EU test method A.6 [Council Regulation (EC) No 440/2008] with the modified flask method. The test item was not filtrated before the assay.

The unfiltrated test item is under the conditions of the test and in the tested concentration not completely miscible with water. Opalescent floating particles could be observed. It was assumed that the test item contains insoluble as well as good water-soluble components.

Water solubility (at 24.7 °C): not determinable.

Description of key information

In a first study, the unfiltrated test substance was not completely miscible with water. Therefore, in a subsequent study, the filtrated test substance was used and a solubility of ≥ 147 g/L was determined. The filtrated test substance was reported to be completely miscible with water. No turbidity was reported, but that the solution had remained clear.

As the test substance is a surfactant (surface tension was tested to be 37.3 nM/m), the critical micelle concentration (cmc) was determined since this is regarded the most relevant parameter for water solubility of substances with surface activity. The critical micelle concentration (cmc) of Sophorolipids: fermentation products of glucose and fatty acids, C18 (unsaturated), glycerol esters with yeast Candida, partially hydrolysed, was determined with a tensiometer by plotting surface tension (mN/m) against concentration of the test item in solution (%).

The cmc of Sophorolipids is 0.02 – 0.04 % (active matter). Based on the assumption the density of the solution is 1 kg/L, this leads to a maximum solubility of Sophorolipids in water of 0.2 – 0.4 g/L.

Key value for chemical safety assessment

Water solubility:

0.4 g/L

at the temperature of:

20 °C

Additional information

As the test substance is a surfactant (surface tension was tested to be 37.3 nM/m), the critical micelle concentration (cmc) was determined since this is regarded the most relevant parameter for water solubility of substances with surface activity. The critical micelle concentration (cmc) of Sophorolipids: fermentation products of glucose and fatty acids, C18 (unsaturated), glycerol esters with yeast Candida, partially hydrolysed, was determined with a tensiometer by plotting surface tension (mN/m) against concentration of the test item in solution (%). The cmc of Sophorolipids is 0.02 – 0.04 % (active matter). Based on the assumption the density of the solution is 1 kg/L, this leads to a maximum solubility of Sophorolipids in water of 0.2 – 0.4 g/L.

The solubility of the filtrated substance in water was determined according to OECD guidline 105 (adopted on 27 July 1995) with the flask method (modified) at 23 °C. The water solubility was checked visually. A value of >= 147 g/L was determined. It could be concluded that under the conditions of the test the substance was completely miscible with water.

As the test substance is surface active (surface tension was tested to be 37.3 nM/m), the critical micelle concentration (cmc) was determined in a preliminary study since this is regarded to be the most relevant parameter for water solubility of substances with surface activity.