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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
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:
For detailed description on the model and its applicability, see attached QMRF and QPRF document.
Principles of method if other than guideline:
Calculation based on KOCWIN v2.00, Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.
GLP compliance:
no
Type of method:
other: calculation
Media:
soil
Type:
log Koc
Value:
3.18 dimensionless
Temp.:
25 °C
Remarks on result:
other: Estimate from MCI
Type:
log Koc
Value:
3.64 dimensionless
Temp.:
25 °C
Remarks on result:
other: Estimate from log Kow
Type:
Koc
Value:
1 500 L/kg
Temp.:
25 °C
Remarks on result:
other: Estimate from MCI
Type:
Koc
Value:
4 409 L/kg
Temp.:
25 °C
Remarks on result:
other: Estimate from log Kow

As no single computational model could be identified which would fit completely to the substance, the log Koc of the substance was calculated as the arithmetic mean of the data generated by two individual QSAR approaches. The QSAR model using the log Kow as input parameter was based on the experimentally determined log Kow of 5.66 (25 °C, pH 5.7, OECD 123).

 

Method

Type

Value

Estimate from MCI

log Koc

3.1762

 

Koc

1500 L/kg

Estimate from log Kow

log Koc

3.6444

 

Koc

4409 L/kg

Arithmetic mean

log Koc

3.4103

 

Koc

2954.5 L/kg

 

The resulting arithmetic mean log Koc was 3.41 with a corresponding Koc of 2954.5 L/kg.

Conclusions:
The substance fits into the applicability domain of the (Q)SAR model. The prediction is valid and can be used for classification and risk assessment. The calculated mean arithmetic mean log Koc was 3.41 (Koc = 2954.5 L/kg).

Description of key information

log Koc = 3.18 (KOCWIN v2.0, MCI method)

log Koc = 3.64 (KOCWIN v2.0, log Kow method)

log Koc = 3.41 (arithmetic mean, KOCWIN v2.0)

Key value for chemical safety assessment

Koc at 20 °C:
2 954.5

Additional information

The log Koc was calculated by the KOCWIN v2.00 model in EPISuite v4.11, using both the Molecular Connectivity Index (MCI) method and the log Kow based method.

The molecular weight and log Kow of the substance fell within the applicability domain of the models and contained no fragments, which were not represented in the model training set. The estimated log Koc values are 3.18 (Koc = 1500 L/kg, MCI estimate) and 3.64 (Koc = 4409 L/kg, log Kow estimate), resulting in an arithmetic mean log Koc of 3.41 (Koc = 2954.5 L/kg). This result indicates that the substance has a potential for sorption to sediment and soil.

[LogKoc: 3.41]

[LogKoc: 3.47]

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