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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
April 04, 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
Deviations:
yes
Remarks:
see 'Principles of method if other than guideline'
Principles of method if other than guideline:
The draft guideline states that the measurement of adsorption coefficient should be carried out on substances in their ionised and unionised forms. However, the dissociation constants of certain functional groups found in the test substance 70 % made it impossible to satisfy these criteria. Testing would be required at pH 2.7 or below for the acidic functional group. Therefore, as pH 2.7 or below is outside the environmental pH range for this test, testing was carried out at approximately neutral pH with the functional group ionised.
GLP compliance:
yes
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Details on study design: HPLC method:
The sample, formamide and reference standard solutions were injected in duplicate using the following HPLC parameters:

HPLC system: Hewlett-Packard 1050, incorporating autosampler and workstation
Column: Luna 5µ CN (250 mm x 4.6 mm id)
Column temperature: 30 °C
Mobile phase: methanol:water (55:45 v/v)
pH of mobile phase: 7.1, obtained using 1.0 M sodium hydroxide
Flow rate: 1 ml/min
UV detector wavelength: dead time and reference standards: 210 nm sample: 205 nm
Injection volume: 10 µL
Details on test conditions:
Preparation of sample solution:

Test substance (0.0312 g) was diluted to 50 mL with methanol.

Preparation of reference solutions:

The dead time was determined by measuring the retention time of formamide (purity 99.5%, 1.10 x 103 mg/L solution in methanol). Solutions of reference standards were prepared in methanol (Acetanilide, Phenol, Atrazine, lsoproturon, Aniline, Linuron, Naphthalene, Fenthion, α EndosuIfan, Diclofop-methyl, Phenanthrene, DDT).
Key result
Sample No.:
#1
Type:
log Koc
Value:
> 1.25 dimensionless
pH:
7
Temp.:
30 °C
Key result
Sample No.:
#2
Type:
log Koc
Value:
> 1.25 dimensionless
pH:
7
Temp.:
30 °C
Details on results (HPLC method):
The draft guideline states that the measurement of adsorption coefficient should be carried out on substances in their ionised and unionised forms. However, the dissociation constants of certain functional groups found in the test substance 70 % made it impossible to satisfy this criteria. Testing would be required at pH 2.7 or below for the acidic functional group. Therefore, as pH 2.7 or below is outside the environmental pH range for this test, testing was carried out at approximately neutral pH with the functional group ionised.
Validity criteria fulfilled:
yes
Conclusions:
Under the study conditions, the estimated adsorption coefficient (Koc) of the test substance on soil and on sewage sludge was less than 17.8, log Koc <1.25.
Executive summary:

A study was conducted to determine the adsorption coefficient of the test substance (Ammonium 2-mercaptopropionate) on soil and on sewage sludge according to OECD Guideline 121 (HPLC method). Testing was carried out at approximately neutral pH with the functional group ionised. Under the study conditions, the estimated adsorption coefficient (Koc) of the test substance on soil and on sewage sludge was less than 17.8, log Koc <1.25 (O'Connor, 2000).

Description of key information

Key value for chemical safety assessment

Koc at 20 °C:
17.8

Additional information

A study was conducted to determine the adsorption coefficient of the test substance (Ammonium 2-mercaptopropionate) on soil and on sewage sludge according to OECD Guideline 121 (HPLC method). Testing was carried out at approximately neutral pH with the functional group ionised. Under the study conditions, the estimated adsorption coefficient (Koc) of the test substance on soil and on sewage sludge was less than 17.8, log Koc <1.25 (O'Connor, 2000).