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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
Study period:
2014
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 (incl. QA statement)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Test temperature:
In order to ensure a stable performance of the HPLC column, the column temperature was set to 40°C. The reference Koc-values in
the OECD guideline presumably refer to 25°C.
Details on study design: HPLC method:
- Equipment: HPLC Agilent 1100
- Column type: length: 250 mm, inner diameter: 4 mm
- Stationary Phase: LiChrospher 100 CN, 5 μm particle size
- Supplier: Fa. Merck
- Mobile Phase: A: 835 ml demineralized water (Millipore) + 165 ml buffer pH 6 (Fluka, Art. No.: 33545);
B: Acetonitrile (Merck, LiChrosolve, Art. No.: 1.00030)
- Solvent program: 60 % A and 40 % B
- Flow: 1 ml/min
- Column temperature: 40 °C
- Injection volume: 3 μL
- Detector: UV, 220

The test is performed at pH 6 (e.g. by adding citrate buffer to the mobile phase)
Type:
log Koc
Value:
4
Temp.:
25 °C
Remarks on result:
other: pH: 6.2
Type:
Koc
Value:
10 000
Temp.:
25 °C
Remarks on result:
other: pH: 6.2
Type:
log Koc
Value:
3.7
Temp.:
25 °C
Remarks on result:
other: calculated for the isomeric structures of the test item with the software KOCWIN v2.00 (U.S. EPA)
Details on results (HPLC method):
The HPLC chromatogram of the test item ditolylether showed one signal for all ditolylether isomers, which all eluting at 8.9 minutes. Even though the column temperature was 40°C, this temperature has no influence on the result of the determination. Therefore the Koc -value of the test item determined within this study also refers to 25 °C.

In order to comply with the guideline OECD 121 and considering environmental relevance, pH 6 was chosen as pH value for the buffer.

In case more than 10 % of the test item is dissociated at pH 6, a second test has to be performed at a pH where test item is undissociated.

No pKa value of the test item ditolylether could be calculated because no ionizable centers are available (calculated with the software ACD/pKa v 7.0 at the structure of the test item).Therefore the undissociated form of the test item ditolylether exist between pH values of 0–14.

Validity criteria fulfilled:
not specified
Conclusions:
An adsorption coefficient (log Koc) of 4 was determined at pH 6.2. The result can be expected to be equal at 25 °C.
Executive summary:

For ditolyl ether the adsorption coefficient was estimated by the HPLC-method according to OECD TG 121. The test was performed at pH 6.2 (environmental relevant). An adsorption coefficient (log Koc) of 4.0 was determined. Even though the column temperature was 40°C, this temperature has no influence on the result of the determination. Therefore the logKoc-values of ditolyl ether determined within this study also refers to 25 °C.

Description of key information

An adsorption coefficient (log Koc) 4.0 was determined at pH 6. The result can be expected to be equal at 25 °C.

Key value for chemical safety assessment

Koc at 20 °C:
10 000

Additional information

Even though the column temperature was 40°C, this temperature has no influence on the result of the determination. Therefore the

logKoc-values of the test item determined within this study also refers to 25 °C and respectively to 20 °C.

[LogKoc: 4.0]

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