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Reference
Endpoint:
adsorption / desorption
Remarks:
adsorption
Type of information:
(Q)SAR
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Justification for type of information:
Estimation Using Log Kow

A traditional method of estimating soil adsorption Koc involves correlations developed with log octanol-water partition coefficient (log Kow) (Doucette, 2000).  Since an expanded experimental Koc database was available from the new MCI regression, it was decided to develop a log Kow estimation methodology that was potentially more accurate than existing log Kow QSARs for diverse structure datasets. 

Effectively, the new log Kow methodology simply replaces the MCI descriptor with log Kow and derives similar equations.  The derivation uses the same training and validation data sets.  The training set is divided into the same non-polar (no correction factors) and correction factor sets.  The same correction factors are also used. 

Separate equations correlating log Koc with log Kow were derived for nonpolar and polar compounds because it was statistically more accurate to do so than to use the approach taken with the MCI-based method.  The equation derived by the non-polar (no correction factor) regression is:


 log Koc  =  0.8679 Log Kow  -  0.0004

    (n = 68, r2 = 0.877, std dev = 0.478, avg dev = 0.371)

One non-polar compound was removed from the regression (hexabromobiphenyl) because it was the only compound without a recommended experimental log Kow and the accuracy of its estimated log Kow (9.10) is suspect.  This equation is used for any compound having no correction factors.
 

For the multiple-linear regression using correction factors, log Kow was included as an individual descriptor.  For compounds having correction factors, the equation is:

  log Koc  =  0.55313 Log Kow  +  0.9251 + ΣPfN  

where ΣPfN is the summation of the products of all applicable correction factor coefficients from Appendix D multiplied by the number of times (N) that factor is counted for the structure.

 
Guideline:
other: REACH guidance on QSARs R.6 May/July 2008
Principles of method if other than guideline:
EPI Suite v4.11, Kocwin v2.20 KOW method
GLP compliance:
no
Type of method:
other: estimation
Specific details on test material used for the study:
CCCCOCCOCCOC(=O)C(C)=C
Key result
Type:
log Koc
Value:
2.393
Remarks on result:
other: estimation based on log Pow 3.10
Conclusions:
Log Koc of Butyldigylcol methacrylate was estimated with EpiSuite v4.1 (KOCWIN (v2.00). Based on a measured log Pow the log Koc was estimated to be 2.393
Executive summary:

Log Koc of Butyldigylcol methacrylate was estimated with EpiSuite v4.11 (KOCWIN (v2.00). Based on a measured log Pow the log Koc was estimated to be 2.393

Description of key information

Estimated Log Koc at 20 °C = 2.393 based  on log Pow = 3.1

Key value for chemical safety assessment

Koc at 20 °C:
247

Additional information

Log Koc of Butyldigylcol methacrylate was estimated with EpiSuite v4.1 (KOCWIN (v2.00). Based on a measured log Pow the log Koc was estimated to be 2.393. The substance is non-ionising and readily biodegradable.Therefore testing of adsorption/desorption is not required.