Farnesol

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Remarks:

adsorption

Type of information:

(Q)SAR

Adequacy of study:

key study

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
EPISuite v4.1 (2012)

2. MODEL (incl. version number)
KOCWIN v2.00

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
CAS number: 4602-84-0
EC number: 225-004-1
Chemical name: 2,6,10-Dodecatrien-1-ol, 3,7,11-trimethyl-
Structural formula: C15H26O
SMILES: OCC=C(CCC=C(CCC=C(C)C)C)C

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: Organic carbon-sorption partition coefficient (organic carbon; Koc)
- Unambiguous algorithm:
a) Molecular Connectivity Index Method Algorithm:
For non-polar substances: Log Koc = 0.5213 MCI + 0.60
For polar substances: Log Koc = 0.5213 MCI + 0.60 + Σ PfN
b) Log Kow Method Algorithm:
For non-polar substances: Log Koc = 0.8679 Log Kow – 0.0004
For polar substances: Log Koc = 0.55313 Log Kow + 0.9251 + Σ PfN
- Defined domain of applicability: The applicability domain of the model is determined by the molecular weight range of the training (min: 32.04, max: 665.02, average 224.4) and validation (min: 73.14, max. 504.12, average: 277.8) datasets, and the structural fragments identified, and their maximum number in any of the 447 training set compounds. Koc estimates are possibly less accurate for compounds outside the MW range of the training set compounds, and/or that have more instances of a given fragment than the maximum for all training set compounds. It is also possible that a compound may have a functional group(s) or other structural features not represented in the training set, and for which no fragment coefficient or correction factor was developed. These points should be taken into consideration when interpreting model results.
- Appropriate measures of goodness-of-fit and robustness and predictivity: The MCI methodology is somewhat more accurate than the Log Kow methodology, although both methods yield good results. If the Training datasets are combined into one dataset of 516 compounds (69 having no corrections plus 447 with corrections), the MCI methodology has an r2, standard deviation and average deviation of 0.916, 0.330 and 0.263, respectively, versus 0.86, 0.429 and 0.321 for the Log Kow methodology.
- Mechanistic interpretation:
a) Molecular Connectivity Index Method: Adsorption is caused by temporary (reversible) or permanent bonding between the substance and a surface. Such bonding can be due to van der Waals interactions, hydrogen bonding to hydroxyl groups, dipole-dipole interactions, ionic interactions, covalent bonding et cetera. The extent to which a substance bonds to a surface thus is dependent on the chemical structure of the substance, and its susceptibility to undergo different types of chemical interactions. The Molecular Connectivity Index Method uses the chemical structure of the substance as the primary starting point, by calculation of the substance-specific MCI value. Subsequently, a distinction is made between nonpolar and polar organics, where for the polar organic molecules an additional correction factor is taken into account for the presence of each structural fragment in the molecule.
b) Log Kow Method: It has been observed that sorption generally increases with increasing hydrophobicity of the substance. As a consequence, a strong linear relationship exists between Koc and Kow. This relationship serves as the basis for the Log Kow Method. Like with the MCI method, a distinction is made between polar and non-polar chemicals, and additional correction factors are taken into account for the presence of the structural fragments in the molecule.

5. APPLICABILITY DOMAIN
- Descriptor domain: The molecular weight of the test substance (222.37 g/mol) falls within the molecular weight domain of the training set (32.04 to 665.02 g/mol) and validation set (73.14 to 504.12 g/mol). The training set is based on 447 compounds and the validation dataset includes 158 compounds.
- Structural and mechanistic domains: Correction factors are available for structural fragments for the MCI method and Log Kow method of Koc estimation. The test substance Koc was calculated by applying the correction factor for an aliphatic alcohol (-C-OH) for each respective estimation method.
- Similarity with analogues in the training set: There are 21 compounds included in the training set for calculation of the aliphatic alcohol correction factor, with a maximum of one occurrence of the hydroxyl group. The test substance contains one hydroxyl group, therefore the use of this structural fragment correction factor is appropriate.
- Other considerations: KOCWIN estimates the soil adsorption coefficient (Koc) of organic compounds. This parameter describes the extent to which a chemical partitions between solid and solution phases in soil and aquatic ecosystems. The Koc is defined as “the ratio of the amount of chemical adsorbed per unit weight of organic carbon in the soil or sediment to the concentration of the chemical in solution at equilibrium”, and is expressed in units of L/kg. Predictions of the Koc are based on the first-order molecular connectivity index (MCI), group contribution factors and experimental values.

6. ADEQUACY OF THE RESULT
The predicted Koc may be used to assess the environmental exposure of the test substance for regulatory purposes (i.e. REACH).

Principles of method if other than guideline:

- Software tool(s) used including version: EPISuite v4.1 (2012)
- Model(s) used: KOCWIN v2.00
- Model description: see field 'Justification for non-standard information' and 'Attached justification'
- Justification of QSAR prediction: see field 'Justification for type of information' and 'Attached justification'

GLP compliance:

no

Remarks:

QSAR calculation

Type of method:

other: QSAR calculation

Media:

other: QSAR calculation

Key result

Type:

Koc

Value:

>= 1 143 - <= 1 438 L/kg

Remarks on result:

other: Estimated from range of log Kow of 4.60 to 4.78

Key result

Type:

log Koc

Value:

>= 3.058 - <= 3.158 dimensionless

Remarks on result:

other: Estimated from log Kow range of 4.60 to 4.78

Key result

Type:

Koc

Value:

1 332 L/kg

Remarks on result:

other: Estimated from log Kow weighted average of 4.72

Key result

Type:

log Koc

Value:

3.124 dimensionless

Remarks on result:

other: Estimated from log Kow weighted average of 4.72

Key result

Type:

Koc

Value:

1 666 L/kg

Remarks on result:

other: Estimated from molecular connectivity index

Key result

Type:

log Koc

Value:

3.22 dimensionless

Remarks on result:

other: Estimated from molecular connectivity index

Key result

Type:

Koc

Value:

1 499 L/kg

Remarks on result:

other: Mean of results derived from the log Kow and MCI method

Key result

Type:

log Koc

Value:

3.176 dimensionless

Remarks on result:

other: Mean of results derived from the log Kow and MCI method

Validity criteria fulfilled:

not applicable

Remarks:

Calculated value

Conclusions:

Based on a log Kow of 4.72 (weighted average), the Koc was 1332 L/kg and the log Koc was 3.1244. Based on the molecular connectivity index, the Koc was 1666 L/kg and the log Koc was 3.22. Using the mean of the results from the log Kow and MCI method, the Koc was determined to be 1499 L/kg and the log Koc was 3.176.

Executive summary:

The adsorption coefficient has been calculated by QSAR (KOCWIN v2.0) and is considered reliable with restriction (Klimisch 2) for this endpoint as it is within the molecular weight domain and a correction factor is available for a suitable substance structural fragment. Based on a log Kow of 4.72 (weighted average), the Koc was 1332 L/kg and the log Koc was 3.1244. Based on the molecular connectivity index, the Koc was 1666 L/kg and the log Koc was 3.22. Using the mean of the results from the log Kow and MCI method, the Koc was determined to be 1499 L/kg and the log Koc was 3.176.

Description of key information

Based on a log Kow of 4.72 (weighted average), the Koc was 1332 L/kg and the log Koc was 3.1244. Based on the molecular connectivity index, the Koc was 1666 L/kg and the log Koc was 3.22. Using the mean of the results from the log Kow and MCI method, the Koc was determined to be 1499 L/kg and the log Koc was 3.176.

Key value for chemical safety assessment

Koc at 20 °C:

1 499

Additional information

The adsorption coefficient has been calculated by QSAR (KOCWIN v2.0) and is considered reliable with restriction (Klimisch 2) for this endpoint as it is within the molecular weight domain and a correction factor is available for a suitable substance structural fragment. Based on a log Kow of 4.72 (weighted average), the Koc was 1332 L/kg and the log Koc was 3.1244. Based on the molecular connectivity index, the Koc was 1666 L/kg and the log Koc was 3.22. Using the mean of the results from the log Kow and MCI method, the Koc was determined to be 1499 L/kg and the log Koc was 3.176.

[LogKoc: 3.176]

[LogKoc: 3.18]