Branched and linear octadecanoic acid, esters with glycerol oligomers

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

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

unsuitable test system

Remarks:

Test system not suitable for determination of water solubility of surface active substances.

Principles of method if other than guideline:

Development of an analytical method for quantitative determination of test material from HPLC water to support solubility measurement.

GLP compliance:

no

Type of method:

other: Determination of solubility based on visual inspection.

Remarks:

1000 and 100 mg/L concentration solutions were prepared with direct weighting of the test item. The 10, 1 and 0.1 mg/L solutions were prepared by serial dilutions. All concentration solutions were visually investigated and compared.

Key result

Remarks on result:

other: Test system not suitable for determination of water solubility of surface active substances.

Results of solubility tests

250 mg/L solutions prepared with sonication. The resulted milky solution contained micelles but no residual test item was observed. The micelles were stable, no sedimentation was observed after 2 days

The formed micelles solubilized the test item, so the saturated solution is not achievable. The concentration of the test item in the colloid solution highly depends on the way of agitation and the contact time.

Results of partition experiment

Detection of the Test Item Compounds

Based on the structure of the test item high retention was expected on the reserved phase.

The test item was eluted with very high methanol content gradient (from 80% to 98% in 2 minutes and kept for 10 minutes, 0.5 mL/min flow rate).

The polyglycerol fraction eluted without retention, there was no difference in the retention times.

The higher the grade of the glycerol oligomerization degree the lower retention times were observed and the intensities were decreasing in the same order.

With low intensity two members of the triglycerol fractions were detected. Based on the results above, the fractions of the test item were detectable in Scan mode.

The 4,4’-DDT as the highest applicable log P_OW reference material was run with water:methanol 25:75 ratio (the highest methanol concentration applicable according to the OECD 117).

The 10 μg/mL concentration test item solution was injected to generate the characteristic base peak chromatograms (UV detection).

All the monoester components were eluted after the 4,4’-DDT so the expected log P_OW are higher than 6.5.

Conclusion

The test item is soluble in HPLC water and ISO media but forms micelles (as a non-ionic surfactant creates real colloid system). The saturated solution is not achievable so the determination of the water solubility is not applicable.

The components of the test item are detectable in the HPLC-MS system.

The observed retention properties of the test item fractions are in the two ends of the partition scale. The free polyglycerol fraction migrates in without retention in the column but the mono-, di- and triester fractions are over the 6.5 reference material.

Reference 2

Endpoint:

water solubility

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Accepted calculation method

Principles of method if other than guideline:

Calculation based on WSKOWWIN v1.42, Estimation Programs Interface Suite™ for Microsoft® Windows v4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.

GLP compliance:

no

Type of method:

other: QSAR

Water solubility:

0.03 mg/L

Temp.:

25 °C

Remarks on result:

other: No information on pH

Remarks:

OC(COCC(O)COC(=O)CCCCCCCCCCCCCCC(C)C)CO

Water solubility:

0.138 mg/L

Temp.:

25 °C

Remarks on result:

other: No information on pH

Remarks:

OC(COCC(O)COCC(O)CO)COC(=O)CCCCCCCCCCCCCCC(C)C

Water solubility:

0 mg/L

Temp.:

25 °C

Remarks on result:

other: No information on pH

Remarks:

OC(COCC(O)COC(=O)CCCCCCCCCCCCCCC(C)C)COC(=O)CCCCCCCCCCCCCCC(C)C

QSAR result; pH is not reported. For detailed description of the model and its applicability, see "Any other information on materials and methods incl. tables”.

Description of key information

Weight of Evidence (WoE)

Additional information

Weight of Evidence (WoE) approach

Experimental study (RL 3):

Method development for water solubility of substance, but test system not suitable for determination of water solubility of surface active substances.

+ QSAR (RL 2):

(KOWWIN v1.68) of three representatives contained in substance (please see constituents 1,2 and 4 as described in section 1.2)

Constituent 1

Water solubility (estimated): 0.03034 mg/L

Constituent 2

Water solubility (estimated): 0.138 mg/L

Part of constituent 3

Water solubility (estimated): 3.854E-11 mg/L

The calculation of the water solubility in these cases is based on an estimated Log Pow (calclulated with KOWWIN v.1.68, please see endpoint Partition coefficient) as no experimental melting point is available. Therefore, it has to be taken into account, if this Log Pow calculation is valid or not to evaluate the validity of the estimated results for water solubility.

Based on the results of endpoint Partition coefficient, only the first representative constituent fits completely in the applicability domain of the model regarding the calculated Log Pow. Therefore, only for this compound the prediction of water solubility could be valid and could be used for classification and risk assessment, if the compound also fits in the applicability domain of the model used to calculate the water solubility (WSKOWWIN v.1.42 in this case).

Taken this consideration into account, the first representative constituents does fit in both applicability domains of both models (KOWWIN v.1.68 + WSKOWWIN v.1.42). Therefore, this prediction of water solubility is valid and can be used for classification and risk assessment.

As the two other representatives do not fit completely in at least one applicability domain of one model, the water solubility predictions of those compounds is not valid and can not be used for classification and risk assessment.

But as the main differences compared to the first compound are a higher molecular weight and a higher number of non-polar, aliphatic CH2 -groups, presumably leading to a lower water solubility, a range for the complete substance can be estimated based on the valid prediction of the first compound:

Water solubility (estimated) < 0.03034 mg/L