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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
calculation (if not (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, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Principles of method if other than guideline:
Calculation based on KOCWIN v2.00, Estimation Programs Interface Suite™ for Microsoft® Windows v 4.10. US EPA, United States Environmental Protection Agency, Washington, DC, USA.
GLP compliance:
no
Type of method:
other: calculation
Media:
soil
Specific details on test material used for the study:
- Name of test material (as cited in study report): sodium prop-2-enesulphonate
- Molecular formula (if other than submission substance): 144.12
- Molecular weight (if other than submission substance): C3 H5 O3 S1 Na1
- Smiles notation (if other than submission substance): S(=O)(=O)(O([Na]))CC=C
Key result
Type:
Koc
Value:
1.568
Temp.:
25 °C
Remarks on result:
other: based on MCI
Type:
log Koc
Value:
0.195
Temp.:
25 °C
Remarks on result:
other: based on MCI

KOCWIN Program (v2.00) Results:

==============================

SMILES : S(=O)(=O)(O([Na]))CC=C

CHEM  : 2-Propene-1-sulfonic acid, sodium salt

MOL FOR: C3 H5 O3 S1 Na1

Koc may 144.12be sensitive to pH!

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

NOTE: METAL (Na, Li or K) HAS BEEN REMOVED TO ALLOW ESTIMATION via MCI!

Koc Estimate from MCI:

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

First Order Molecular Connectivity Index ........... : 3.061

Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 2.1953

Fragment Correction(s):

1  Sulfonic acid (-S(=O)-OH) ....................... : -2.0000

Corrected Log Koc .................................. : 0.1953

 

Estimated Koc: 1.568 L/kg  <===========

Executive summary:

QPRF: KOCWIN v2.00 (18 Nov. 2013)

 

1.

Substance

See “Test material identity”

2.

General information

 

2.1

Date of QPRF

See “Data Source (Reference)”

2.2

QPRF author and contact details

See “Data Source (Reference)”

3.

Prediction

3.1

Endpoint
(OECD Principle 1)

Endpoint

Adsorption to solid phase of soils etc.

Dependent variable

Organic carbon normalised adsorption coefficient (Koc)

3.2

Algorithm
(OECD Principle 2)

Model or submodel name

KOCWIN

Model version

v. 2.00

Reference to QMRF

QMRF: Estimation of Soil Adsorption Coefficient using KOCWIN v2.00 (EPI Suite v4.11): Estimation using log Kow

Predicted value (model result)

See “Results and discussion”

Input for prediction

- Chemical structure via CAS number or SMILES

- log Kow (for log Kow method; optional)

Descriptor values

- Chemical structure

- Correction factors

3.3

Applicability domain
(OECD principle 3)

Domains:

1) Molecular weight
(range of test data set: 32.04 to 665.02 g/mol; On-Line KOCWIN User’s Guide, Ch. 6.2.4 Domain)

Substance within range (144.12 g/mol)

2) log Kow (range of test data set: -2.11 to 8.12; On-Line KOCWIN User’s Guide, Appendices E & F)

Substance(not) within trainings set but within validation set (-3.68)

3) Correction factors: Number of instances of the identified correction factor does not exceed the maximum number as listed in Appendix D (On-Line KOCWIN User’s Guide)

Not fulfilled.

One correction was applied which is not listed in Appendix D (= Sulfonic acid : -2.0)

3.4

The uncertainty of the prediction
(OECD principle 4)

Nonpolar compounds: n = 68; r2=0.478, average dev. = 0.371

Polar compounds: n = 447, r²=0.855, std. dev. = 0.396, average dev. = 0.307

3.5

The chemical mechanisms according to the model underpinning the predicted result
(OECD principle 5)

Adsorption is caused by temporary (reversible) or permanent bonding between the substance and a surface (e.g. due to van der Waals interactions, hydrogen bonding to hydroxyl groups, ionic interactions, covalent bonding, etc.). The organic carbon normalized adsorption coefficient (Koc) is the ratio of a substance concentration sorbed in the organic matter component of soil or sediment to that in the aqueous phase at equilibrium.

Estimation using log Kow: The model is based on the high correlation of log Kow and the adsorption potential.

 

References

- US EPA (2012). On-Line KOCWIN User’s Guide.

- Meylan, W., P.H. Howard and R.S. Boethling. 1992. Molecular topology/fragment contribution method for predicting soil sorption coefficients. Environ. Sci. Technol. 26: 1560-1567.

 

 

Assessment of estimation domain (molecular weight, fragments, correction factors):

Model:  KOCWIN v2.00 MCI & Log Kow method
Substance:  2-Propene-1-sulfonic acid, sodium salt
CAS-#:  2495-39-8
SMILES:  S(=O)(=O)(O([Na]))CC=C
Molecular weight (g/mol): 144,12
Log Kow (experimental data): -3,68 Reference: EPISUITE - KOWWIN data base match
           
  Molecular weight (g/mol)   log Kow
Minimum Maximum Average   Minimum Maximum
Training set 32,04 665,02 224,4   -2,11 8,12
Validation set 73,14 504,12 277,8   -5,98 8,68
Assessment of molecular weight Molecular weight within range of training and validation set.
 
             
Assessment of log Kow (only relevant for log Kow method) Log Kow within range of validation set, but not within training set. Therefore, the estimate may be less accurate.
             
Appendix D. MCI & Log Kow Correction Factors for 447 Compound Training Set    
Correction Factor Descriptor Coefficient for Molecular Connectivity Index (MCI) Regression Methodology Coefficient for log Kow Regression Methodology Occurrence No. of instances
of each bond
found for the
current substance
(new model)  Remark (number of compounds (max per structure)  
.
(a) Counted up to twice per structure, regardless of number of occurrences. .
(b) Either one or both carbons aromatic; if both carbons aromatic, can not be cyclic. .
(c) Any nitrogen attached to double bond isnotcounted; also, carbonyl and thiocarbonyl arenotcounted as carbons. .
(d) This is theonlyfragment counted, even if other fragments occur. .
(e) Not included in regression derivation; estimated from other carbonyl fragments. .
(f) Counted only once per structure, regardless of number of occurrences. .

 

Description of key information

Adsorption to solid soil phase is not expected.

Key value for chemical safety assessment

Additional information

As calculated using SRC PCKOCWIN v2.00, the Koc of the test substance is 1.56 (log Koc = 0.1953 ) [BASF SE, 2010].