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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
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
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. QA statement)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Test temperature:
25 °C (column temperature)
Details on study design: HPLC method:
EQUIPMENT
- Apparatus:
- Type: Agilent 1050 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: Acetonitrile:tetrahydrofuran:buffer solution (30:25:45 v/v/v), where a phosphate buffer solution was employed for the pH 4 test and a borate buffer solution for the pH 9 test
- Experiments with additives carried out on separate columns: no additives used
- pH: 4 and 9
- Solutes for dissolving test and reference substances: Acetonitrile:tetrahydrofuran:buffer solution (10:40:50 v/v/v); although the organic:aqueous ratio approximated to that of the mobile phase, a higher THF:acetonitrile ratio was employed to ensure dissolution of test substance at the test concentration

DETERMINATION OF DEAD TIME
- Method: by inert substances which are 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: 8 µg
- Quantity of reference substances:
Formamide (internal deadtime standard): 1 µg, Acetanilide: 0.05 µg, Nitrobenzene: 0.05 µg, Naphthalene: 0.02 µg, 2-Methylnaphthalene: 0.03 µg, Anthracene: 0.1 µg, DDT: 0.1 µg
- Intervals of calibration: before and after injections of the test substance

REPETITIONS
- Number of determinations: two

EVALUATION
- Determination of the log Koc value: A calibration plot of log10k versus log10Koc was constructed for the reference standards. The logarithms of the capacity factors for the test substance were calculated and the log10Koc values were determined by interpolation or extrapolation, as appropriate.
Key result
Type:
log Koc
Value:
< 2.5
Temp.:
25 °C
Remarks on result:
other: at pH 4
Key result
Type:
log Koc
Value:
< 1.3
Temp.:
25 °C
Remarks on result:
other: at pH 9
Details on results (HPLC method):
- pH 4 test: the majority (approx. 80% by chromatographic area) of the components of the test material were found to have retention times less than approx. 3.9 minutes corresponding to LogKoc values of less than 2.5.
- Retention times of reference substances used for calibration:
acetanilide (3.4 min), nitrobenzene (4.1), naphthalene (4.5), 2-methylnaphthalene (4.6), anthracene (4.9), DDT (6.7)
- Details of fitted regression line: log10Koc = 5.16 log10k + 4.72

- pH 9 test: all major components of the test material were found to have retention times less than that of the lowest reference standard, acetanilide, indicating LogKoc values of less than 1.3.
Validity criteria fulfilled:
not applicable

Description of key information

Log Koc at 25 °C: < 2.5 and < 1.3 at pH 4 and 9, respectively (HPLC method; OECD 121, EU C.19)

Key value for chemical safety assessment

Additional information

Log Koc at 25 °C: < 2.5 (pH 4) and < 1.3 (pH 9)

The test material is a UVCB substance.

At pH 4, approximately 80% (by chromatographic area) of the components of the test material were found to have Log Koc values of less than 2.5.

At pH 9, all components were found to have Log Koc values of less than 1.3.