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Solubility in organic solvents / fat solubility

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Reference
Endpoint:
solubility in organic solvents / fat solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
in March 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Qualifier:
according to
Guideline:
other: OECD Guideline 105, Method A6 of Commission Regulation (EC) No. 440/2008
Version / remarks:
2008
Deviations:
yes
Remarks:
Due to lack of an official guideline for determination of octanol solubility, the procedure for the test was performed according to the procedure described in the guideline OECD 105, which is applied for determination of water solubility.
GLP compliance:
no
Key result
Medium:
n-octanol
Solubility:
ca. 4.8 g/L
Remarks on result:
other: determined at room temperature
Test substance stable:
not determined
Details on results:
- Temperature effects: not reported
- Examination of different polarities: not applicable
- Information on chemical stability: not described
- for raw data, please see section "any other information on results incl. tables".

Due to the lack of reference substances a direct quantitative evaluation of the components in the HPLC/CAD analysis was not possible.

In order to provide an estimation of the acidic and lactonic SL content, an alternative approach was chosen by “evaluated as” calculations where all components are quantified applying the calibration function of one available reference compound. Thus, all identified acidic Sophorolipids components were quantified against a calibration function established for an acidic SL-reference material specifically synthesized, purified and characterized by NMR and HPLC.

A similar reference substance was prepared for the lactonic form, which was characterized for its SL-Lactone content by NMR and HPLC and which was used as calibration standard for all lactonic components.

The approach of quantifying the component groups against one typical representative can provide a reasonable quantitative estimation as it is our experience that the response of surfactant products at the CAD detection is mainly determined by the molecular structure but not primarily by chain length of the fatty acid.

Analytical results

Results of solubility of the test item in 1-octanol:

 SL-acid [g/L]  SL-Lactone [g/L]  Sum [g/L]
 2.3  2.9  5.2
 1.7  2.4  4.1
 2.2  2.9  5.1
 Average: 2.1  Average: 2.7  Average: 4.8

The composition of the obtained results does not reflect the composition of the original sample because lactonic Sophorolipids are better soluble in octanol than acidic Sophorplipids. Besides, it was observed the formation of a mixed phase in which the lactonic SLs contribute to the solubilization of acidic SLs in octanol. Therefore, the octanol solubility of Sophorolipids is influenced by the composition of the active content in the sample used for test procedure.

Conclusions:
The solubility of the test item in n-octanol was determined to be 4.8 g/L.
Executive summary:

In this study, the solubility of Sophorolipids: fermentation products of glucose and fatty acids, C18 (unsaturated), glycerol esters with yeast Candida, partially hydrolysed, in n-octanol was determined. Due to lack of an official guideline for determination of octanol solubility, the procedure for the test was performed according to the procedure described in guideline OECD Guideline 105, Method A6 of Commission Regulation (EC) No. 440/2008, which is applied for determination of water solubility.

The test item was stirred in n-octanol for 72 hours and then let equilibrate for 24 hours at room temperature before HPLC analysis was performed. A mixed phase in which the lactonic SLs contribute to the solubilization of acidic SLs in octanol was observed. Therefore, the octanol solubility of Sophorolipids is influenced by the composition of the active content in the sample used for test procedure.

The solubility of the test item in n-octanol was determined to be 4.8 g/L.

Description of key information

The solubility of the test item in n-octanol was determined to be 4.8 g/L.

Key value for chemical safety assessment

Solubility in organic solvents at 20°C:
4.8 g/L

Additional information

The solubility of Sophorolipids: fermentation products of glucose and fatty acids, C18 (unsaturated), glycerol esters with yeast Candida, partially hydrolysed, in n-octanol was determined. Due to lack of an official guideline for determination of octanol solubility, the procedure for the test was performed according to the procedure described in guideline OECD Guideline 105, Method A6 of Commission Regulation (EC) No. 440/2008, which is applied for determination of water solubility.

The test item was stirred in n-octanol for 72 hours and then let equilibrate for 24 hours at room temperature before HPLC analysis was performed. A mixed phase in which the lactonic SLs contribute to the solubilization of acidic SLs in octanol was observed. Therefore, the octanol solubility of Sophorolipids is influenced by the composition of the active content in the sample used for test procedure.

The solubility of the test item in n-octanol was determined to be 4.8 g/L.