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Reference
Endpoint:
adsorption / desorption, other
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
EPIWIN software by US-EPA

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

3. SMILES
CCOc1ccc2NC(C)(C)C=C(C)c2c1

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: log Koc – soil adsorption coefficient of organic compounds
- Unambiguous algorithm: log Koc  =  0.5213 MCI  +  0.60 + ΣPfN  
MCI – molecular connectivity index, ΣPfN - summation of the products of all applicable correction factor coefficients available in the data set multiplied by the number of times (N) that factor is counted for the structure.
- Defined domain of applicability: Currently, there is no universally accepted definition of model domain. The training set of the model contains diverse molecules, so that the fragment library is abundant. It is however possible that a compound has functional groups or other structural features that are not represented in the training set and for which no fragment coefficients were developed. Additionally, there can be more instances of a given fragment than the maximum for all training set compounds. These points should be taken into consideration while interpreting test results.
Molecular weight limits of the training set: 32 - 665 g/mol
Log Kow limits: -2.11-9.10
- Appropriate measures of goodness-of-fit and robustness and predictivity: for the statistics, training data set has been split up into two subsets: the one containing non-polar substances with no fragments subjected to corrections (i.e. those with ΣPfN = 0) and the one containing the remaining ones. For the non-polar set: N = 69 compounds, correlation coefficient R2 = 0.967, standard deviation sd = 0.247 and average deviation ad = 0.199. For the second set: N = 447 compounds, correlation coefficient R2 = 0.9, standard deviation sd = 0.34 and average deviation ad = 0.273. For the external validation data set: N = 158 compounds, correlation coefficient R2 = 0.85, standard deviation sd = 0.583 and average deviation ad = 0.459. For the 516 compounds in the training set, 93% are within 0.6 log units and 100% within 1 log unit.
- Mechanistic interpretation: The methodology and relationship between the forst order molecular connectivity index (MCI) and adsorption coefficient is outlined in the reference paper: Meylan, W., P.H. Howard and R.S. Boethling, "Molecular Topology/Fragment Contribution Method for Predicting Soil Sorption Coefficients", Environ. Sci. Technol. 26: 1560-7 (1992). MCI was initially successfully used to predict soil sorption coefficients for non-polar organics, and the developed new estimation method based on MCIand series of statistically derived fragment contribution factors made it useful also for the polar ones.

5. APPLICABILITY DOMAIN
Molecular weight of ca. 217.31 in molecular weight limits of the training set: 32 - 665 g/mol; log Kow of 3.39 in log Kow limits: -2.11 - 9.10; applicability domain fulfilled

6. ADEQUACY OF THE RESULT
The organic substance Quinoline, 6-ethoxy-1,2-dihydro-2,2,4-trimethyl- lies within the applicability domain with a molecular weight of 217.31 and a log Kow of 3.39; the result seems reasonable and is considered as adequate and acceptable to use this result for risk assessment purposes.
Guideline:
other: REACH guidance on QSARs Chapter R.6
Version / remarks:
May 2008
Principles of method if other than guideline:
Meylan, W., P.H. Howard and R.S. Boethling, "Molecular Topology/Fragment Contribution Method for Predicting Soil Sorption Coefficients", Environ. Sci. Technol. 26: 1560-7 (1992).
GLP compliance:
no
Remarks:
(not applicable)
Type of method:
other: QSAR calculation
Media:
soil
Specific details on test material used for the study:
SMILES: CCOc1ccc2NC(C)(C)C=C(C)c2c1
Computational methods:
Using the computer tool KOCWIN v2.00 by US-EPA (EPIWIN) the organic-normalized sorption coefficient for soil (soil adsorption, Koc) can be estimated. The following two different models are used: Salbjic molecular connectivity method (MCI) and the traditional method, which is based on the logPow value of the substance. In general, the MCI method is taken more seriously into account, due to the fact that it includes improved correction factors.
Key result
Type:
Koc
Value:
1 269 L/kg
Temp.:
25 °C
Remarks on result:
other: MCI based estimate includes improved correction factors - most relevant
Type:
log Koc
Value:
3.1 dimensionless
Temp.:
25 °C
Remarks on result:
other: MCI based estimate includes improved correction factors - most relevant
Type:
Koc
Value:
1 197 L/kg
Temp.:
25 °C
Remarks on result:
other: LogPow-based estimate (traditional method)
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

SMILES : O(c(ccc(NC(C=C1C)(C)C)c12)c2)CC

CHEM   : Quinoline, 6-ethoxy-1,2-dihydro-2,2,4-trimethyl-

MOL FOR: C14 H19 N1 O1

MOL WT : 217.31

---------------------------  KOCWIN v2.00 Results  ---------------------------

 Koc Estimate from MCI:

 ---------------------

        First Order Molecular Connectivity Index  ........... :  7.516

        Non-Corrected Log Koc (0.5213 MCI + 0.60)  .......... :  4.5179

        Fragment Correction(s):

                 1   Nitrogen to non-fused aromatic ring ...  : -0.5225

                 1   Ether, aromatic  (-C-O-C-)  ...........  : -0.6791

                 1   Nitrogen to Carbon (aliphatic) (-N-C)..  : -0.2127

        Corrected Log Koc  .................................. :  3.1035

                        Estimated Koc:  1269  L/kg   <===========

 Koc Estimate from Log Kow:

 -------------------------

        Log Kow  (Kowwin estimate)  ......................... :  3.87

        Non-Corrected Log Koc (0.55313 logKow + 0.9251)  .... :  3.0657

        Fragment Correction(s):

                 1   Nitrogen to non-fused aromatic ring ...  : -0.0216

                 1   Ether, aromatic  (-C-O-C-)  ...........  :  0.0559

                 1   Nitrogen to Carbon (aliphatic) (-N-C)..  : -0.0218

        Corrected Log Koc  .................................. :  3.0782

                        Estimated Koc:  1197  L/kg   <===========

Validity criteria fulfilled:
yes
Remarks:
(Scientifically accepted calculation method.)
Conclusions:
The study report describes a scientifically accepted calculation method for the soil absorption characteristics using the US-EPA software KOCWIN v2.00. No GLP criteria are applicable for the usage of this tool and the QSAR estimation is easily repeatable. The result (Koc = 1269 L/kg; log Koc = 3.1) is adequate for the regulatory purpose.
Executive summary:

The prediction for soil adsorption property of the test substance was determined by the computer program KOCWIN v2.00 (EPIWIN software) by US-EPA .The program estimates the organic-normalized sorption coefficient for soil, which is designated as Koc. The following two models are used: the Salbjic molecular connectivity (MCI) method as well as the traditional method which is based on the logPow value of the substance.

The MCI method is taken more seriously into account, due to the fact that is includes improved correction factors, resulting in a Koc value of 1269 L/kg (corrected log Koc = 3.104).The traditional method gives a value of 1197 L/kg (corrected log Koc = 3.078).

Description of key information

Calculation with KOCWIN v2.00 (EPIWIN software by US-EPA), organic-normalized sorption coefficient (Koc): 1269 L/kg (MCI method estimation)

Key value for chemical safety assessment

Koc at 20 °C:
1 269

Additional information

The key value was determined by QSAR estimation [with KOCWIN v2.00 (EPIWIN software by US-EPA)]. The program estimates the organic-normalized sorption coefficient for soil, which is designated as Koc. The following two models are used: the Salbjic molecular connectivity (MCI) method as well as the traditional method which is based on the logPow value of the substance. The traditional method gives a value of 1197 L/kg. The MCI method is taken more seriously into account, due to the fact that it includes improved correction factors, resulting in a Koc value of 1269 L/kg (corrected log Koc = 3.1). According to these results, the substance has a potential for sorption onto soil organic matter.

[LogKoc: 3.1]

[LogKoc: 3.1]