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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
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:
no
Qualifier:
according to
Guideline:
EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC estimation method
Radiolabelling:
no
Test temperature:
25 °C (column temperature)
Details on study design: HPLC method:
EQUIPMENT
- Apparatus:
- Type: Agilent 1200 Series Liquid Chromatograph
- Type, material and dimension of analytical (guard) column: HyperClone 5µ CN (CPS) (25 cm x 4.6 mm internal diameter)
- Detection system: UV set at 210 nm

MOBILE PHASES
- Type: methanol:water (55:45 v/v)
- Experiments with additives carried out on separate columns: no additives used
- pH: no data
- Solutes for dissolving test substance: methanol (filtrate (0.45 µm, PTFE) of a saturated solution of the test substance in methanol, prepared by mixing the test substance with this solvent for 7 days at 20˚C. Dissolution of the test substance is poor in water-miscible solvents)
- Solutes for dissolving reference substances: HPLC mobile phase

DETERMINATION OF DEAD TIME
- Method: by inert substance which is not retained by the column (formamide)

REFERENCE SUBSTANCES
- Identity: Acetanilide, Nitrobenzene, Naphthalene, 2-Methylnaphthalene, Anthracene, DDT
- Known logKoc values: 1.3, 2.4, 2.8, 3.9, 4.4, 5.6

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: not applicable, since the filtrate of a saturated solution of the test substance in methanol was used
- Quantity of reference substances:
Formamide (internal deadtime standard): 4.0 µg, Acetanilide: 0.2 µg, Nitrobenzene: 0.2 µg, Naphthalene: 0.05 µg, 2-Methylnaphthalene: 0.05 µg, Anthracene: 0.2 µg, DDT: 0.2 µg

EVALUATION
- Qualitative comparison of chromatograms obtained for the test and reference substances.
Key result
Type:
log Koc
Value:
> 5.6
Temp.:
25 °C
Details on results (HPLC method):
- Retention times of reference substances used for calibration: acetanilide (3.6 min), nitrobenzene (4.3), naphthalene (5.3), 2-methylnaphthalene (6.0), anthracene (8.3), DDT (14.9)
- Average retention data for test substance: There were no significant peaks present in the test substance chromatogram before the retention time of DDT, the highest available reference standard with a known log10Koc value of 5.6.
It was thus considered either that the method was inapplicable due to the components of the test substance being too insoluble for detection, or that any soluble components of the test substance eluted after DDT (or did not elute under the conditions of the analysis).
As confirmation, computer modelling (KOCWIN, Version 2.00, U.S. Environmental Protection Agency) was used and indicated log10Koc values between 7 and 8 for representative constituents of the test substance.
Validity criteria fulfilled:
not applicable

Description of key information

Log Koc at 25 °C: >5.6  (HPLC method; OECD 121, EU C.19)

Key value for chemical safety assessment

Additional information

The main components of the test material were found to have LogKoc values greater than 5.6