Registration Dossier

Environmental fate & pathways

Adsorption / desorption

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
adsorption / desorption: screening
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, but not (completely) 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.
Reference:
Composition 0
Qualifier:
according to
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
Test material information:
Composition 1
Details on test conditions:
BASIS FOR CALCULATION OF Koc:
- Estimation software: ChemProp v6.5, Franco, Fu and Trapp 2009 model for acids
- Log Kow: -4.9 at 20 °C (OECD 105, Flask method)
- pKa: 0.95 / 4.78 / 6.26
- pH: 4, 7, 9
Type:
log Koc
Value:
0.77 dimensionless
pH:
7
% Org. carbon:
5
Remarks on result:
other:
Remarks:
based on eq. 2 (acids)
Type:
Koc
Value:
5.88 L/kg
pH:
7
% Org. carbon:
5
Remarks on result:
other:
Remarks:
based on eq. 2 (acids)

For detailed information on the results please refer to the attached report.

Description of key information

log Koc = 0.77 (pH 7, pKa 6.22, ChemProp v6.5, acid model)

Koc = 5.88 (pH 7, pKa 6.22, ChemProp v6.5, acid model)

Key value for chemical safety assessment

Koc at 20 °C:
5.88

Additional information

There is no experimental study available, in which the log Koc of the target substance 2-[3-[(4-Amino-2-methylpyrimidin-5-yl)methyl]-4-methyl-1,3-thiazoniol-5-yl]ethyl dihydrogen diphosphate (CAS 136-09-4) was assessed. Therefore, the log Koc was calculated by ChemProp v6.5 using the acid model at the environmentally relevant pH values of 4, 7, and 9 at which two different charged species of the parent compound predominate. The required input parameters for the calculations using ChemProp are the pKa (4.78 at pH 4 and 6.25 at pH 7 and 9) as well as the log Kow (-4.9 at 20 °C, OECD 105, Flask method).

The calculated log Koc values are -0.37 at pH 4, 0.77 at pH 7 and 1.00 at pH 9, indicating that the substance has a low potential for sorption to sediment and soil. The value obtained at pH 7 is retained as key value.

[LogKoc: 0.769]