Sophorolipids: fermentation products of glucose and rapeseed-oil fatty acids methyl esters with yeast Candida Bombicola

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Deviations:

no

GLP compliance:

no

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Type:

log Pow

Partition coefficient:

>= 2 - <= 4.6

Remarks on result:

other: see details on results section

Details on results:

The octanol/water partitions coefficients (log Pow) of Sopholiance S are :
- Log P = 2.0 for product D (mean of two determinations)
- Log P = 2.9 for product C (mean of two determinations)
- Log P = 3.4 for product B (mean of two determinations)
- Log P = 3.8 for product A’(mean of two determinations)
- Log P = 4.6 for product A (mean of two determinations)

Test item n-octanol/water partition coefficient results for first run

 

Test item	Retention Time(min)	Value of the Capacity factor k	Value of log k	Value of log P
Product D	8.007	0.639	-0.194	2.0
Product C	10.237	1.096	0.040	2.9
Product B	12.200	1.497	0.175	3.4
Product A’	14.357	1.939	0.288	3.8
Product A	19.500	2.992	0.476	4.6

Test item n-octanol/water partition coefficient results for second run

 

Test item	Retention Time(min)	Value of the Capacity factor k	Value of log k	Value of log P
Product D	8.014	0.641	-0.193	2.0
Product C	10.290	1.106	0.044	2.9
Product B	12.274	1.513	0.180	3.4
Product A’	14.454	1.959	0.292	3.8
Product A	19.647	3.022	0.480	4.6

Conclusions:

The octanol/water partitions coefficients (log Pow) of Sopholiance S are :
- Log P = 2.0 for product D (mean of two determinations)
- Log P = 2.9 for product C (mean of two determinations)
- Log P = 3.4 for product B (mean of two determinations)
- Log P = 3.8 for product A’(mean of two determinations)
- Log P = 4.6 for product A (mean of two determinations)

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

>= 3.9 - <= 5.4

Temp.:

25 °C

Remarks on result:

other: pH not measured

Details on results:

In the conditions of the test, the chromatograms of the test item show six peaks with relative peak areas of 11.1%, 4.2%, 13.3%, 54.1%, 5.5% and 11.8%. These peaks correspond respectively to partition coefficients (Log Pow) of 3.9, 4.0, 4.4, 4.6, 4.7 and 5.4. The determination was performed at 25 °C (temperature of the column) but the values obtained can be considered to represent the values at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log Kow values were determined. Log Kow values of the test and reference substances are assumed to vary with temperature in the same way.

The log Kow values are reported correctly in the first paragraph of section 5 and in appendix 1 of the report, e.g. 3.9, 4.0, 4.4, 4.6, 4.7 and 5.4.

However, in other parts of the report the log Kow value of 4.0 corresponind to the second peak has been incorrectly typed as 4.2. 

Conclusions:

In the conditions of the test, the chromatograms of Freeze dried Sopholiance show six peaks at average retention times of: 7.89 minutes (11.1% relative peak area), corresponding to a partition coefficient (log value) of 3.9, 8.49 minutes (4.2% relative peak area), corresponding to a partition coefficient (log value) of 4.0, 10.49 minutes (13.3% relative peak area), corresponding to a partition coefficient (log value) of 4.4, 11.92 minutes (54.1% relative peak area), corresponding to a partition coefficient (log value) of 4.6, 12.77 minutes (5.5% relative peak area), corresponding to a partition coefficient (log value) of 4.7 and 18.89 minutes (11.8% relative peak area), corresponding to a partition coefficient (log value) of 5.4.
Therefore: Partition coefficients n-octanol/water of the constituents of Freeze dried Sopholiance:
log Pow = 3.9, 4.0, 4.4, 4.6, 4.7 and 5.4

Description of key information

The partition coefficient n-octanol/water of the registered substance was determined by the reverse phase HPLC method according to OECD Guidelines, Method 117. This method is appropriate for UVCB or multi-component substance as individual constituents / groups of constituents may be resolved / partially resolved into separate peaks. Two studies are available, Processium 2012 (supporting study) and Dutriez 2019 (key study), which resulted in log Kow ranges of 2.0-4.6 and 3.9-5.4 respectively.

The first study (Processium 2012) is a supporting study because it was not performed under GLP and the report does not included copies of the HPLC chromatograms.

In contrast, the Dutriez 2019 study was performed according to GLP, includes copies of the HLPC chromatograms and gives measured log Kow values that are closer to those predicted by Kowwin (v1.68) for the four main constituents of the registered substance (predicted values = 4.93, 5.33, 5.47 and 5.61). In the conditions of the test, the chromatograms of the test item show six peaks with relative peak areas of 11.1%, 4.2%, 13.3%, 54.1%, 5.5% and 11.8%. These peaks correspond respectively to partition coefficients (Log Pow) of 3.9, 4.0, 4.4, 4.6, 4.7 and 5.4. The determination was performed at 25 °C (temperature of the column) but the values obtained can be considered to represent the values at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log Kow values were determined. Log Kow values of the test and reference substances are assumed to vary with temperature in the same way.

For the purpose of the environmental risk assessment, a whole substance approach is being used. A log Kow value of 4.6 has been selected as the key value because it corresponds both to the weighted average [e.g. 3.9(*0.11) + 4.0(*0.042) + 4.4(*0.133) + 4.6(*0.541) + 4.7(*0.055) + 5.4(*0.118) = 4.57] and the value of the most abundant peak in the key study (Dutriez, 2019).

Key value for chemical safety assessment

Log Kow (Log Pow):

4.6

Additional information

For the purposes of classification and labelling, the substance is considered to have bioaccumulative potential since ~ 89% w/w of the substance has a log Kow ≥ 4. For the purpose of the PBT assessment, the substance is considered to contain some constituents that are potential B based on three peaks in the logKow determination being >4.5.