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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:
other: According to international guideline(s), GLP-compliant, performed in recognized contract research organization, no restrictions, fully adequate for assessment.
Reference:
Composition 1
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
Media:
soil/sewage sludge
Test material information:
Composition 1
Test temperature:
25 °C (column temperature)
Details on study design: HPLC method:
EQUIPMENT
- Apparatus:
- Type: Merck-Hitachi LaChrom HPLC system
- Type, material and dimension of analytical column: LiChrospher 100 CN 250 × 4 mm, 5µm HPLC Column No.: 540779-1
- Detection system: UV set at 205 nm

MOBILE PHASES
- Type: Acetonitrile:water 6:4, isocratic
- Solutes for dissolving test and reference substances: stock solutions were prepared in acetonitrile and diluted with HPLC mobile phase, except sodium nitrate which was dissolved in HPLC mobile phase

DETERMINATION OF DEAD TIME
- Method: by inert substance which is not retained by the column: sodium nitrate (RT = 1.30 min)

REFERENCE SUBSTANCES
- Identity (known log Koc): acetanilide (1.25), methyl benzoate (1.80), triazophos (2.55), naphthalene (2.75), fenthion (3.31), α-endosulfan (4.09)

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: about 0.46 µg
- Quantity of reference substances: approx. 0.2 µg except for triazophos (approx. 0.46 µg) and sodium nitrate (approx. 2 µg)
- Intervals of calibration: three series of the reference solutions and the test item solution were measured alternately, with two replicate injections

REPETITIONS
- Number of determinations: two

EVALUATION
- Determination of the log Koc value: A calibration plot of log k' versus log Koc was prepared for the reference standards. The calibration equation was determined by linear regression using the least squares method. The capacity factors k' were calculated from the dead time and retention times of the reference substances. The log k' data of the reference substances were plotted against their log Koc values.
Key result
Type:
log Koc
Value:
<= 2.5
Temp.:
25 °C
Details on results (HPLC method):
Approximately 94% (by chromatographic area) of the components of the test material were found to have Log Koc values below 1.25 (mean retention time ≤ 2.43 min). The remaining 6% eluted as one peak with a Log Koc value of 2.5 (mean retention time 3.29 min).
- Retention times of reference substances used for calibration:
sodium nitrate: 1.30, acetanilide: 2.75, methyl benzoate: 3.05, triazophos: 3.42, naphthalene: 3.48, fenthion: 3.67, α-endosulfan: 4.00 minutes
- Details of fitted regression line: log k' = 0.093 log Koc – 0.047 (Rsq = 0.966)
Validity criteria fulfilled:
not applicable

Description of key information

Log Koc at 25 °C: ≤ 2.5  (HPLC method; OECD 121, EU C.19)

Key value for chemical safety assessment

Additional information

Approximately 94% of the components of the test material (by chromatographic area) were found to have Log Koc values of lower than 1.25. The remaining 6% eluted as one peak with a Log Koc value of 2.5.