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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption
Remarks:
adsorption/desorption
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
key study
Study period:
06th February 2013
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was not conducted because the Guideline states that the test is not appropriate for strong acids. The Koc value was instead calculated via two accepted QSPR methods. the study therefore can be assessed as reliable with restrictions.
Qualifier:
according to
Guideline:
other:
Version / remarks:
Using KOCWIN, version 2.00, © 2000-2008 U.S. Environmental Protection Agency, the adsorption coefficient of the test item was estimated (MCI method and Kow method).
Qualifier:
according to
Guideline:
other:
Version / remarks:
P. J. McCall, D. A. Laskowski, R. L. Swann and H. J. Dishburger “Measurement of Sorption Coefficients of Organic Chemicals and Their Use in Environmental Fate Analysis”; 1981; Assoc. of Off. Anal. Chem., Arlington, VA; p 89 – 109.
Principles of method if other than guideline:
The adsorption coefficient of Methyl phosphonic acid 70 % was estimated using a computer-based atom fragment contribution method, KOCWIN, version 2.00, © 2000-2008 U.S. Environmental Protection Agency.
GLP compliance:
no
Type of method:
other: QSAR
Test temperature:
not reported
Details on study design: HPLC method:
n/a
Details on sampling:
n/a
Details on matrix:
n/a
Details on test conditions:
n/a
Computational methods:
Using KOCWIN, version 2.00, © 2000-2008 U.S. Environmental Protection Agency, the adsorption coefficient of the test item was estimated (MCI method and Kow method).
Type:
Koc
Value:
1.41
Remarks on result:
other: Calculation (MCI method)
Type:
log Koc
Value:
0.148
Remarks on result:
other: Calculation (MCI method)
Type:
Koc
Value:
7.53
Remarks on result:
other: Calculation (Kow method)
Type:
log Koc
Value:
-0.1
Remarks on result:
other: Calculation (Kow method)
Details on results (HPLC method):
n/a
Adsorption and desorption constants:
n/a
Recovery of test material:
n/a
Concentration of test substance at end of adsorption equilibration period:
n/a
Concentration of test substance at end of desorption equilibration period:
n/a
Details on results (Batch equilibrium method):
n/a
Statistics:
n/a
Validity criteria fulfilled:
yes
Conclusions:
Using KOCWIN, version 2.00, © 2000-2008 U.S. Environmental Protection Agency, the adsorption coefficient of the test item was estimated to be 1.41 (MCI method) and 7.53 x 10-2 (Kow method), log10 Koc 0.148 (MCI method) and -1.12 (Kow method). These values indicate that the test item will have a very high environmental mobility.
However, it is anticipated that partitioning forces with the organic carbon content of soils and sediments may not be the dominant force controlling the mobility of the test item in the environment. Strong ionic interaction with clay particles, for example, will also influence the fate of the test item in the environment.
Executive summary:

Practical testing according to Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001 was not possible due to the strong acidity of the test item. Test guidance indicates that OECD 121 is not applicable to strong acids. Therefore, the adsorption coefficient of Methyl phosphonic acid 70 % was estimated using a computer-based atom fragment contribution method, KOCWIN, version 2.00, © 2000-2008 U.S. Environmental Protection Agency. Using KOCWIN, version 2.00, © 2000-2008 U.S. Environmental Protection Agency, the adsorption coefficient (Koc) was estimated to be 1.41 (MCI method) and 7.53 x 10-2 (Kow method), log10 Koc 0.148 (MCI method) and -1.12 (Kow method). The test item was evaluated as the mono-sodium salt, to ensure that it was evaluated at an environmentally relevant pH. These calculated values indicate that the test item will have a very high environmental mobility *. However, it is anticipated that partitioning forces with the organic carbon content of soils and sediments may not be the dominant force controlling the mobility of the test item in the environment. Strong ionic interaction with clay particles, for example, will also influence the fate of the test item in the environment.

* According to P. J. McCall, D. A. Laskowski, R. L. Swann and H. J. Dishburger “Measurement of Sorption Coefficients of Organic Chemicals and Their Use in Environmental Fate Analysis”; 1981; Assoc. of Off. Anal. Chem., Arlington, VA; p 89 – 109.

Description of key information

Using KOCWIN the adsorption coefficient of the test item was estimated to be 1.41 (MCI method) and 7.53 x 10-2 (Kow method). These values indicate that the test item will have a very high environmental mobility. However, it is anticipated that partitioning forces with the organic carbon content of soils and sediments may not be the dominant force controlling the mobility of the test item in the environment. Strong ionic interaction with clay particles, for example, will also influence the fate of the test item in the environment.

Key value for chemical safety assessment

Koc at 20 °C:
1.41

Additional information

Practical testing according to Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001 was not possible due to the strong acidity of the test item. Therefore, the adsorption coefficient of Methyl phosphonic acid 70 % was estimated using a computer-based atom fragment contribution method, KOCWIN, version 2.00, © 2000-2008 U.S. Environmental Protection Agency. The adsorption coefficient (Koc) was estimated to be 1.41 (MCI method) and 7.53 x 10-2 (Kow method), log10 Koc 0.148 (MCI method) and -1.12 (Kow method). These calculated values indicate that the test item will have a very high environmental mobility (McCall 1981). However, it is anticipated that partitioning forces with the organic carbon content of soils and sediments may not be the dominant force controlling the mobility of the test item in the environment. Strong ionic interaction with clay particles, for example, will also influence the fate of the test item in the environment.

* P. J. McCall, D. A. Laskowski, R. L. Swann and H. J. Dishburger “Measurement of Sorption Coefficients of Organic Chemicals and Their Use in Environmental Fate Analysis”; 1981; Assoc. of Off. Anal. Chem., Arlington, VA; p 89 – 109.

[LogKoc: 0.148]