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Environmental fate & pathways

Adsorption / desorption

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Administrative data

Endpoint:
adsorption / desorption
Remarks:
adsorption
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Accepted calculation method, substance within applicability domain

Data source

Referenceopen allclose all

Reference Type:
other: EPIWin calculation
Title:
Unnamed
Year:
2014
Report Date:
2014
Reference Type:
other: Estimation software
Title:
Estimation Programs Interface Suite for Microsoft Windows, v4.11
Author:
US EPA
Year:
2012
Bibliographic source:
United States Environmental Protection Agency, Washington, DC, USA

Materials and methods

Principles of method if other than guideline:
Calculation using KOCWIN (v2.00) Molecular Connectivity Index (MCI)
GLP compliance:
no
Type of method:
other: QSAR estimation: KOCWIN v2.00: Koc estimate from MCI

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material: 1-Penten-4-yne, 3-(1-ethoxyethoxy)-3-methyl-

Study design

Test temperature:
25 °C

Results and discussion

Adsorption coefficientopen allclose all
Type:
Koc
Value:
57.98
Temp.:
25 °C
Remarks on result:
other: The substance is within the applicability domain of the model.
Type:
log Koc
Value:
1.763
Temp.:
25 °C
Remarks on result:
other: The substance is within the applicability domain of the model.

Any other information on results incl. tables

Koc Estimate from MCI:

First Order Molecular Connectivity Index

5.576

Non-Corrected Log Koc (0.5213 MCI + 0.60)

3.5065

Fragment Correction(s)

 

2 Ether, aliphatic (-C-O-C-)

-1.7432

Corrected Log Koc

1.7633

Estimated Koc

57.98 L/kg

Applicant's summary and conclusion

Executive summary:

QPRF: KOCWIN v2.00 (MCI methodology) (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): MCI methodology

Predicted value (model result)

See “Results and discussion”

Input for prediction

- Chemical structure via CAS number or SMILES

Descriptor values

- MCI (first order molecular connectivity index)

- 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 (168.24 g/mol)

2) 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)

Fulfilled.

3.4

The uncertainty of the prediction
(OECD principle 4)

Statistical accuracy for training dataset:

n = 516, r² = 0.916, std. dev. = 0.330, average dev.= 0.263

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.

MCI methodology: The first-order molecular connectivity index is a measure to describe a variety of properties of chemicals. According to Sabljic (1984; cited in Meylan et al., 1992), the soil sorption potential is highly correlated with the first order MCI. Therefore, it has been used to derive the adsorption coefficient.

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):

Training set: Molecular weights

Training set

Validation set

Minimum

32.04

73.14

Maximum

665.02

504.12

Average

224.4

277.8

Assessment of molecular weight

Molecular weight within range of training set

Training set: Log Kow

Training set

Validation set

Minimum

-2.11

-5.98

Maximum

8.12

8.68

Assessment of log Kow

Log Kow within range of training set

Appendix D. MCI & Log Kow Correction Factors for 447 Compound Training Set

Correction Factor Descriptor

Coefficient for Molecular Connectivity Index (MCI) Regression Methodology

Occurrence

No. of instances

of each bond

found for the

current substance

(new model)

Remark

(number of compounds)

(max per structure)

Ether, aliphatic

(-C-O-C-)

-0.871597

 

20

2

2