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Reference
Endpoint:
adsorption / desorption: screening
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2015
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Generally accepted calculation method on constituents.
Justification for type of information:
QSAR prediction
Qualifier:
no guideline followed
Principles of method if other than guideline:
The Soil Adsorption Coefficient was estimated with the program US EPA EPI Suite (v 4.10), program component KOCWIN (v2.00). The Soil Adsorption Coefficient Program KOCWIN estimates the soil adsorption coefficient (Koc) of organic compounds.  Koc can be defined as "the ratio of the amount of chemical adsorbed per unit weight of organic carbon (oc) in the soil or sediment to the concentration of the chemical in solution at equilibrium".
PCKOCWIN (version 2) estimates Koc with two separate estimation methodologies:
(1) estimation using first-order Molecular Connectivity Index (MCI)
(2) estimation using log Kow (octanol-water partition coefficient)
GLP compliance:
no
Type of method:
other: EPIWIN (v 4.1), KOCWIN (v2.00)
Media:
soil
Computational methods:
Estimation software: KOCWIN v.200 (EpiSuite v.4.11)

PCKOCWIN (version 2) estimates Koc with two separate estimation methodologies:

(1) estimation using first-order Molecular Connectivity Index (MCI)
The equation derived by the non-polar (no correction factor) regression is:

 log Koc  =  0.5213 MCI  +  0.60

    (n = 69, r2 = 0.967, std dev = 0.247, avg dev = 0.199)

Adding in the correction factor regression yields the final MCI equation:

 log Koc  =  0.5213 MCI  +  0.60 + 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.


(2) estimation using log Kow (octanol-water partition coefficient):
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)

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.

Key result
Type:
log Koc
Remarks:
MCI method
Value:
3.992 dimensionless
Remarks on result:
other: Butanedioic acid, 2,3-dihydroxy-[R-(R*,R*)]-, C12 linear alkyl esters
Key result
Type:
log Koc
Remarks:
Kow method
Value:
5.359 dimensionless
Remarks on result:
other: Butanedioic acid, 2,3-dihydroxy-[R-(R*,R*)]-, C12 linear alkyl esters
Key result
Type:
log Koc
Remarks:
MCI method
Value:
3.862 dimensionless
Remarks on result:
other: Butanedioic acid, 2,3-dihydroxy-[R-(R*,R*)]-, C12-branched- alkyl esters
Key result
Type:
log Koc
Remarks:
Kow method
Value:
5.276 dimensionless
Remarks on result:
other: Butanedioic acid, 2,3-dihydroxy-[R-(R*,R*)]-, C12 branched alkyl esters
Key result
Type:
log Koc
Remarks:
MCI method
Value:
4.383 dimensionless
Remarks on result:
other: Butanedioic acid, 2,3-dihydroxy-[R-(R*,R*)]-, C13-branched- alkyl esters
Key result
Type:
log Koc
Remarks:
Kow method
Value:
5.818 dimensionless
Remarks on result:
other: Butanedioic acid, 2,3-dihydroxy-[R-(R*,R*)]-, C13-branched alkyl esters
Statistics:
The KOCWIN model had the following statistics:

#MCI Methodology
---- / Training / Training / Validation
---- / No Corrections / with Corrections / Data set
number / 69 / 447 / 158
r2 corr coef / 0.967/ 0.900 /0.850
std deviation / 0.247 / 0.340 / 0.583
avg deviation / 0.199 / 0.273 / 0.459

#Log Kow Methodology
---- / Training / Training / Validation
---- / No Corrections / with Corrections / Data set
number / 68 / 447 / 150 **
r2 corr coef / 0.877/ 0.855 /0.778
std deviation / 0.478 / 0.396 / 0.679
avg deviation / 0.371 / 0.307 / 0.494


** eight ammonium and metal salt compounds were removed from the Validation dataset

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

a) C12 -linear component

smiles code: CCCCCCCCCCCCOC(=O)C(O)C(O)C(=O)OCCCCCCCCCCCC

Koc Estimate from MCI:

---------------------

First Order Molecular Connectivity Index: 16.540

Non-Corrected Log Koc (0.5213 MCI + 0.60) : 9.2222

Fragment Correction(s):

2 Aliphatic Alcohol (-C-OH): -2.6358

2 Ester (-C-CO-O-C-) or (HCO-O-C): -2.5939

Corrected Log Koc: 3.9924

Estimated Koc: 9827 L/kg

Koc Estimate from Log Kow:

-------------------------

Log Kow (Kowwin estimate): 9.74

Non-Corrected Log Koc (0.55313 logKow + 0.9251): 6.3126

Fragment Correction(s):

2 Aliphatic Alcohol (-C-OH): -0.8229

2 Ester (-C-CO-O-C-) or (HCO-O-C): -0.1312

Corrected Log Koc: 5.3585

Estimated Koc: 2.283e+005 L/kg

b) C12 -branched component:

smiles code: CC(C)CCCCCCCCCOC(=O)C(O)C(O)C(=O)OCCCCCCCCC(C)CC

Koc Estimate from MCI:

---------------------

First Order Molecular Connectivity Index: 16.290

Non-Corrected Log Koc (0.5213 MCI + 0.60) : 9.0917

Fragment Correction(s):

2 Aliphatic Alcohol (-C-OH): -2.6358

2 Ester (-C-CO-O-C-) or (HCO-O-C): -2.5939

Corrected Log Koc: 3.8619

Estimated Koc: 7277 L/kg

Koc Estimate from Log Kow:

-------------------------

Log Kow (Kowwin estimate): 9.59

Non-Corrected Log Koc (0.55313 logKow + 0.9251): 6.2296

Fragment Correction(s):

2 Aliphatic Alcohol (-C-OH): -0.8229

2 Ester (-C-CO-O-C-) or (HCO-O-C): -0.1312

Corrected Log Koc: 5.2755

Estimated Koc: 1.886e+005 L/kg

c) C13 -branched component

smiles code: CC(C)CCCCCCCCCCOC(=O)C(O)C(O)C(=O)OCCCCCCCCCC(C)CC

Koc Estimate from MCI:

---------------------

First Order Molecular Connectivity Index: 17.290

Non-Corrected Log Koc (0.5213 MCI + 0.60) : 9.6130

Fragment Correction(s):

2 Aliphatic Alcohol (-C-OH): -2.6358

2 Ester (-C-CO-O-C-) or (HCO-O-C): -2.5939

Corrected Log Koc: 4.3832

Estimated Koc: 2.417e+004 L/kg

Koc Estimate from Log Kow:

-------------------------

Log Kow (Kowwin estimate): 10.57

Non-Corrected Log Koc (0.55313 logKow + 0.9251): 6.7717

Fragment Correction(s):

2 Aliphatic Alcohol (-C-OH): -0.8229

2 Ester (-C-CO-O-C-) or (HCO-O-C): -0.1312

Corrected Log Koc: 5.8176

Estimated Koc: 6.571e+005 L/kg

Validity criteria fulfilled:
yes
Conclusions:
The substances calculated representing the test substance have high log Kocs indicating adsorption in soil and sediment.
Executive summary:

The log Kocs of the test substance were estimated with the program US EPA EPI Suite (v 4.10), program component KOCWIN (v 2.00). Using a correlation based on molecular connectivity index, the log Koc were determined to be 3.8619 - 4.3832.

Using a correlation based on Kow, the log Koc was 5.2755 and 5.8176. The high Koc values indicate a distinct potential of the test substance to adsorb in soil and sediment.

The McCall classification scheme classifies the substances as slightly mobil (KOC 2000 - 5000) to immobile in soil (Koc > 5000).

Description of key information

The log Kocs of the test substance were estimated with the program US EPA EPI Suite (v 4.10), program component KOCWIN (v 2.00). Using a correlation based on molecular connectivity index, the log Koc were determined to be 3.8619 - 4.3832. Using a correlation based on Kow, the log Koc was 5.2755 and 5.8176. The high Koc values indicate a distinct potential of the test substance to accumulate in soil and sediment. The McCall classification scheme classifies the substances as immobile in soil (Koc > 5000).

Key value for chemical safety assessment

Koc at 20 °C:
657 100

Additional information

[LogKoc: 5.82]

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