Potassium 3-sulphopropyl methacrylate

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

(Q)SAR

Adequacy of study:

supporting 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

Remarks:

organic salt

Justification for type of information:

1. SOFTWARE
EPIWIN software by US-EPA

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

3. SMILES
C(=C)(C)C(=O)OCCCS(=O)(=O)OK

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 first 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. 247.3 in molecular weight limits of the training set: 32 - 665 g/mol; log Kow of -3.1 below log Kow limits: -2.11-9.10; not (completely) falling into its applicability domain

6. ADEQUACY OF THE RESULT
The organic substance potassium 3-sulphopropyl methacrylate lies not completely within the applicability domain with a molecular weight of 247.3 and a log Kow of -3.1; anyway, this QSAR has been entered as supporting study in addition to a data waiver as due to the very low logPow the result seems reasonable and no adsorption potential has to be expected.

Data source

Reference

Title:

EPI Suite Version 4.10

Year:

2012

Bibliographic source:

KOCWIN - Meylan and Howard (1992)

Materials and methods

Test guideline

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

Type of method:

other: QSAR calculation

Media:

soil

Test material

Test material information

Constituent 1

Reference substance name:

Potassium 3-sulphopropyl methacrylate

EC Number:

250-466-6

EC Name:

Potassium 3-sulphopropyl methacrylate

Cas Number:

31098-21-2

Molecular formula:

C7H12O5S.K

IUPAC Name:

potassium 3-(methacryloyloxy)propane-1-sulfonate

Study design

Batch equilibrium or other method

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.

Results and discussion

Adsorption coefficient

Adsorption coefficient 1

Key result

Type:

Koc

Value:

10 L/kg

Temp.:

25 °C

Remarks on result:

other: MCI method, includes improved correction factors - most relevant

Adsorption coefficient 2

Key result

Type:

log Koc

Value:

1 dimensionless

Temp.:

25 °C

Remarks on result:

other: MCI method, includes improved correction factors - most relevant

Adsorption coefficient 3

Type:

Koc

Value:

0.14 L/kg

Temp.:

25 °C

Remarks on result:

other: LogPow-based estimate (traditional method)

Adsorption coefficient 4

Type:

log Koc

Value:

-0.855 dimensionless

Temp.:

25 °C

Remarks on result:

other: LogPow-based estimate (traditional method)

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

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 = 10 L/kg; log Koc = 1) is adequate for the regulatory purpose although the organic substance potassium 3-sulphopropyl methacrylate lies not completely within the applicability domain with a molecular weight of 247.3 and a log Kow of -3.1; anyway, this QSAR has been entered as supporting study in addition to a data waiver as due to the very low logPow the result seems reasonable and no adsorption potential has to be expected.
Koc = 10 L/kg

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 10 L/kg. The traditional method gives a value of 0.1396 L/kg. Potassium has been removed to allow estimation via MCI. It is noted that these results represent a best-fit to the majority of experimental values, due to the fact that the Koc of this structure may be sensitive to the surrounding pH.