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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
ChemProp(TM) Main Module 6.5, Public OSIRIS Edition

2. MODEL (incl. version number)
Franco, Fu & Trapp (Partitioning, soil sorption coefficient, Koc), ionizable substances, acids and bases

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.
Qualifier:
according to guideline
Version / remarks:
REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: ChemProp v6.5
- Model(s) used: Franco, Fu & Trapp
Full reference and details of the used formulas can be found in:
1. Franco A, Fu W, Trapp S 2009. Influence of soil pH on the sorption of ionizable chemicals: Modeling advances. Environ. Toxicol. Chem. 28: 458-464.
2. Franco A, Trapp S 2008. Estimation of the soil-water partition coefficient normalized to organic carbon for ionizable organic chemicals. Environ. Toxicol. Chem. 27: 1995-2004.
- Model description: see field 'attached justification' and 'any other information on material and methods'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'
GLP compliance:
no
Type of method:
other: calculation
Media:
soil
Details on test conditions:
BASIS FOR CALCULATION OF Koc:
- Estimation software: ChemProp v6.5, Franco, Fu and Trapp 2009 model for acids
- Log Kow: 5.7 (OECD 117, HPLC)
- pKa: 3.96 (SPARC v4.6)
- pH: 4, 7, and 9
Type:
log Koc
Value:
4.08 dimensionless
pH:
4
% Org. carbon:
5
Remarks on result:
other: based on eq. 2 (acids)
Type:
Koc
Value:
12 119.48 L/kg
pH:
4
% Org. carbon:
5
Remarks on result:
other: based on eq. 2 (acids)
Type:
log Koc
Value:
2.31 dimensionless
pH:
7
% Org. carbon:
5
Remarks on result:
other: based on eq. 2 (acids)
Type:
Koc
Value:
202.13 L/kg
pH:
7
% Org. carbon:
5
Remarks on result:
other:
Type:
log Koc
Value:
2.17 dimensionless
pH:
9
% Org. carbon:
5
Remarks on result:
other: based on eq. 2 (acids)
Type:
Koc
Value:
147.45 L/kg
pH:
9
% Org. carbon:
5
Remarks on result:
other: based on eq. 2 (acids)

Please refer to the attached reports for detailed information on the results.

Description of key information

log Koc = 4.08 (pH 4, 25 °C, Franco, Fu and Trapp)

log Koc = 2.31 (pH 7, 25 °C, Franco, Fu and Trapp)

log Koc = 2.17 (pH 9, 25 °C, Franco, Fu and Trapp)

Key value for chemical safety assessment

Koc at 20 °C:
202.13

Additional information

No experimental studies are available, in which the adsorption/desorption potential of the Reaction mass of N-(1-oxooctadecyl)sarcosine and N-hexadecanoyl-N-methylglycine (EC 947-850-7) was assessed. Therefore, the log Koc was calculated by QSAR at the environmentally relevant pH values of 4, 7, and 9, using ChemProp v6.5 (Franco, Fu & Trapp, acid model). Since the substance is a multi-constituent the log Koc was calculated for its two main constituents Stearoyl sarcosine (CAS 142-48-3) and Palmitoyl sarcosine (CAS 2421-33-2). The model input parameters are the pH value (4, 7, and 9), the pKa value (3.96 for both molecules, SPARC v4.6) and the log Pn, corresponding to the experimentally determined log Kow of the substance (5.70, OECD 117).

The molecules lie within the applicability domain of the model (pKa and log Kow ranges) and the results were identical for both molecules. The obtained log Koc is 4.08 at pH 4 (Koc = 12119.48 L/kg), 2.31 at pH 7 (Koc = 202.13 L/kg) and 2.17 at pH 9 (Koc = 147.45 L/kg), indicating a moderate potential for adsorption to particles in soil and sediment at environmentally relevant pH of 7 to 9. The log Koc at pH 7 is retained as key value and indicates that the substance is moderately mobile in water at pH 7 and above.