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

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

October 4 to November 18 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

conducted under GLP conditions

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Version / remarks:

2008

Deviations:

yes

Remarks:

see principles of method if other than guideline section

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Version / remarks:

2001

Deviations:

yes

Remarks:

see principles of method if other than guideline section

Principles of method if other than guideline:

Deviations:
Due to a technical failure on the chromatograph the solutions prepared on October 31 could not be injected as foreseen. The analysis was repeated on November 08, 2019. Only the results of this second, successful analysis are reported here in detail.
The calibration mixture was not prepared as foreseen in the study plan by mixing of individual solutions of the reference substances, but by directly adding exactly weighed portions of the reference substances to one flask containing the eluent. The validity of the study is not adversely affected.

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Test temperature:

25°C

Details on study design: HPLC method:

A solution of the test substance was prepared (10.0 mg in 10.0 ml methanol/water 55/45 v/v).
After equilibration of the HPLC system, the calibration mixture was injected first, followed by the test chemical solution twice and the calibration mixture again.
Retention times tr were measured and averaged and the decimal logarithms of the capacity factors k were calculated.
The linear regression parameters of the relationship log Koc = f(log k) were also calculated from the data obtained with the calibration mixture and, therewith, log Koc of the test substance was determined from its measured capacity factor.

Type:

log Koc

Value:

>= 3.9 - <= 4.5 dimensionless

Temp.:

25 °C

Remarks on result:

other: pH not specified

Details on results (HPLC method):

The chromatograms of Freeze dried Sopholiance show six peaks at average retention times of 9.985 minutes, corresponding to an adsorption coefficient (log value) of 3.9 (around 3.4% relative peak area), 10.838 minutes, corresponding to an adsorption coefficient (log value) of 4.0 (around 5.5% relative peak area), 12.235 minutes, corresponding to an adsorption coefficient (log value) of 4.2 (around 17.5% relative peak area), 13.155 minutes, corresponding to an adsorption coefficient (log value) of 4.3 (around 6.1% relative peak area), 13.802 minutes, corresponding to an adsorption coefficient (log value) of 4.4 (around 15.3% relative peak area) and 15.143 minutes, corresponding to an adsorption coefficient (log value) of 4.5 (around 52.1% relative peak area).

N.B.: The determination was performed at 35 °C (temperature of the column), but the value obtained above can be considered to represent the value at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log KOC values were determined. Adsorption coefficients of the test and reference substances are assumed to vary with temperature in the same way.

Validity criteria fulfilled:

yes

Conclusions:

The chromatograms of Freeze dried Sopholiance show six peaks at average retention times of 9.985 minutes, corresponding to an adsorption coefficient (log value) of 3.9 (around 3.4% relative peak area), 10.838 minutes, corresponding to an adsorption coefficient (log value) of 4.0 (around 5.5% relative peak area), 12.235 minutes, corresponding to an adsorption coefficient (log value) of 4.2 (around 17.5% relative peak area), 13.155 minutes, corresponding to an adsorption coefficient (log value) of 4.3 (around 6.1% relative peak area), 13.802 minutes, corresponding to an adsorption coefficient (log value) of 4.4 (around 15.3% relative peak area) and 15.143 minutes, corresponding to an adsorption coefficient (log value) of 4.5 (around 52.1% relative peak area).

Therefore: Adsorption coefficients (Koc) of Freeze dried Sopholiance:
log Koc = 3.9, 4.0, 4.2, 4.3, 4.4 and 4.5

Executive summary:

The adsorption coefficient (Koc) on soild and on sewage sludge of Freeze dried Sopholiance was determined by the Reverse Phase High Performance Liquid Chromatographic Method according to the OECD Guidelines for testing of chemicals Method No. 121.

The result is:

Adsorption coefficients (Koc) of Freeze dried Sopholiance:

log Koc = 3.9, 4.0, 4.2, 4.3, 4.4 and 4.5

Description of key information

The adsorption coefficient (Koc) on soil and on sewage sludge of Freeze dried Sopholiance was determined by the Reverse Phase High Performance Liquid Chromatographic Method according to the OECD Guidelines for Testing of Chemicals, Method No 121. The determination was performed at 25 °C (temperature of the column) but the value obtained can be considered to represent the value at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log Koc values were determined. Adsorption coefficients of the test and reference substances are assumed to vary with temperature in the same way.

The chromatograms of Freeze dried Sopholiance show six peaks, corresponding to an adsorption coefficient (log value) of 3.9 (~3.4% relative peak area), 4.0 (~5.5% relative peak area), 4.2 (~17.5% relative peak area), 4.3 (~6.1% relative peak area), 4.4 (~15.3% relative peak area) and 4.5 (~52.1% relative peak area). The Log Koc of the major peak (4.5) has been chosen as the key value for chemical safety assessment. This corresponds to a value of 31623.

Key value for chemical safety assessment

Koc at 20 °C:

31 623