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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption
Remarks:
other: Adsorption modeling
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2017
Reliability:
2 (reliable with restrictions)
Justification for type of information:
Acceptable calculation method. Meets generally accepted scientific standards, well documented and acceptable for assessment.
Qualifier:
according to guideline
Guideline:
other: Guidance on information requirements and chemical safety assessment, Chapter R.6: QSARs and grouping of chemicals, ECHA, 2008
Deviations:
not applicable
Principles of method if other than guideline:
For calculation of the soil adsorption coefficient (koc) of 1,4-Naphthoquinone the EPI (Estimation Programs Interface) Suite™, a Windows®-based suite of physical/chemical property and environmental fate estimation programs developed by the EPA’s Office of Pollution Prevention Toxics and Syracuse Research Corporation (SRC), was used.
The included program KOCWIN estimates the koc using two different estimation methodologies:
1. the Sabljic molecular connectivity method with improved correction factors
2. the traditional method based on log KOW

The Sabljic molecular connectivity method is solely based on the Molecular Connectivity Index (MCI) which is a method that runs directly from structure to activity. Molecular Connectivity Indices are representation of molecular structure. The molecule is regarded as a sum of the bonds connecting pairs of atoms which are encoded by the cardinal number (delta) and represents the count of all bonded atoms other than hydrogen. The molecule is than splitted into fragments which are encoded by the corresponding delta values. The delta value of each atom forming a bond pair designate a bond value and these values are then summed over all the bonds to calculate the molecular connectivity index.

The traditional method using measured Kow values uses correlations between the log Kow and the Koc. For polar and non-polar compunds separate regression equations are used.
For non-polar compounds: log Koc = 0.8679 log Kow - 0.0004
For polar compounds correction factors are implemented.
Type of method:
other: Adsorption modeling
Media:
other: not applicable
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not applicable
Test temperature:
not applicable
Details on study design: HPLC method:
not applicable
Details on sampling:
not applicable
Details on matrix:
not applicable
Details on test conditions:
not applicable
Computational methods:
See "Principles of method if other than guideline"
Type:
Koc
Value:
ca. 454.4 L/kg
Remarks on result:
other: MCI method
Type:
Koc
Value:
ca. 589.9 L/kg
Remarks on result:
other: Kow method
Details on results (HPLC method):
not applicable
Adsorption and desorption constants:
not applicable
Recovery of test material:
not applicable
Concentration of test substance at end of adsorption equilibration period:
not applicable
Concentration of test substance at end of desorption equilibration period:
not applicable
Details on results (Batch equilibrium method):
not applicable
Statistics:
not applicable

Soil Adsorption Coefficient (KOCWIN v2.00):

Koc : 454.4 L/kg (MCI method)

Log Koc: 2.657 (MCI method)

Koc : 589.9 L/kg (Kow method)

Log Koc: 2.771 (Kow method)

Validity criteria fulfilled:
not applicable
Conclusions:
It can be concluded that 1,4-naphthoquinone has a Koc = 454.4 - 589.6 L/kg. The KOC values derived with EPISuite™, based on the MCI-model and the Kow method, can be considered reliable for both modelling and environmental fate assessments.
Executive summary:

The adsorption coeffcient Koc = 454.4 L/kg (MCI method) or 589.9 L/kg (Kow method) of was determined by a non-experimental calculation method (QSAR).

The KOC values derived with EPISuite™, based on the MCI-model and the Kow method, can be considered reliable for both modelling and environmental fate assessments.

Description of key information

Calculation of log Koc:
For calculation of the soil adsorption coefficient (koc) of 1,4-naphthoquinone the EPI (Estimation Programs Interface) Suite™, a Windows®-based suite of physical/chemical property and environmental fate estimation programs developed by the EPA’s Office of Pollution Prevention Toxics and Syracuse Research Corporation (SRC), was used.
Results log Koc:
Soil Adsorption Coefficient (KOCWIN v2.00):
Koc    :  454.4  L/kg (MCI method)
Log Koc:  2.657       (MCI method)
Koc    :  589.9  L/kg (Kow method)
Log Koc:  2.771       (Kow method)

Key value for chemical safety assessment

Koc at 20 °C:
454.4

Additional information

The adsorption coeffcient log Koc of 1,4-naphthoquinone was determined by a non-experimental calculation reliable QSAR method.

According to the EPI SUITE User's Guide, the MCI methodology is somewhat more accurate than the Log Kow methodology, although both methods yield good results.

No further testing is required.

[LogKoc: 2.657]