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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:
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
GLP compliance:
yes
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Specific details on test material used for the study:
Clear colourless liquid, purity 96.5%.
Radiolabelling:
no
Test temperature:
35 oC
Details on study design: HPLC method:
A HPLC with a spectrophotometric detector was used. Stationary phase: cyanopropyl chemically bound resin on silica basis. Mobile phase: 40/60 (v/v) methanol/water. A temperature controlled column 35 °C was used. The test was performed at neutral pH based on a computer estimated pKa (ionized <10% pH 5.5-7.5).
• The test was performed in duplicate. References were added as a mixture of 5 in methanol and mixed with the mobile phase. Reference blank: 5/95 (v/v) methanol/mobile phase.
• t0: formamide in methanol 5.1 g/l. blank: 10/90 (v/v) methanol/mobile phase.
• 1.3 g/l pentamethyl-trioxepane in mobile phase =stock. Dilute 10x =test. Blank: mobile phase.
Injection: mobile phase, ref., ref. blank, formamide sol., formamide blank, test (in duplicate), blank, ref., formamide sol.

The solutions were injected in the following sequence: mobile phase, the mixtures of reference substances, the reference blank solution, the formamide solution, the formamide blank solution, the test solution (in duplicate), the corresponding blank solution, the mixtures of reference substances and the formamide solution. The chromatograms of the formamide solution and the corresponding blank were recorded for 5 minutes. All other chromatograms were recorded for 50 minutes.
Key result
Sample No.:
#1
Type:
log Koc
Value:
1.7 dimensionless
pH:
7
Temp.:
35 °C
Key result
Sample No.:
#1
Type:
Koc
Value:
50 L/kg
pH:
7
Temp.:
35 °C
Details on results (HPLC method):
Analytical conditions:
Column: Hypersil BDS-CN; 150 x 4.6 (I.D.) mm; dp= um (Alltech, Deerfield, USA)
Column temperature: 35 oC
Mobile phase: 40/60 (v/v) Methanol/Milli-Q water
FLow: 1 ml/min
Detection: UV at 210 nm
Injection volume: 10 ul

T0=1.975 min (mean 1.976 and 1.973). regression line: log k’ =0.42 log Koc-1.08 (r=0.961, n=9)

Reference substances (log Koc): Phenol (1.32), N,N-dimethylbenzamide (1.52), Methylbenzoate (1.80), 3,5-dinitrobenzamide (2.31), Naphtalene (2.75), Mercaptodimethur (3.10), Fenthion (3.31), Phenantrene (4.09) and 2,4-DDT (5.63). pentamethyl-trioxepane log Koc: 1.70
Validity criteria fulfilled:
yes
Conclusions:
Koc 50 (log Koc 1.70) at 35 °C
Executive summary:

Koc5.0*101 (log Koc1.70) at 35 °C

Description of key information

Koc 50 (log Koc 1.70) at 35 °C

Key value for chemical safety assessment

Koc at 20 °C:
50

Additional information

[LogKoc: 1.7]