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adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12 Sep 2013 - 20 Jan 2014
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP - Guideline study
according to guideline
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
GLP compliance:
Type of method:
HPLC estimation method
soil/sewage sludge
Test temperature:
Column temperature: 40 °C
Details on study design: HPLC method:
- Apparatus: UPLC (Waters Acquity H-class/PDA e^λ Detection)
- Type, material and dimension of analytical (guard) column: Waters HSS Cyano ( 2.1 x 50 mm, 1.7 µm); flow rate: 0.2 mL/min
- Detective wave: 210-400 nm scan

- Type: water-acetonitrile (35 : 65)
- Solutes for dissolving test and reference substances: methanol for reference substances and acetonitrile for the test substance (the test substance and reference substances were weighed and dissolved in 10 mL solvent to get stock solutions. Then the stock solutions were diluted with mobile phase to get the working solutions)

- Identity: Thiourea, Acetanilide, Linuron, Naphthalene, 1 ,2,3-Trichloro-benzene, Diclofop-methyl, DDT

- Quantity of test substance introduced in the column: 10 µL
- Quantity of reference substances: 7

- Number of determinations: 2

- Calculation of retention times: 4.95 min and 4.94 min for two injections
- Determination of the log Koc value: based on the regression line, log Koc of the test substance was extrapolated to be 8.10 (according to guideline, at least one reference substance with a log Koc value over that of the test substance should be used. However, the test substance had a very strong retention on the column and its log Koc was over the highest log Koc 5.63 of the reference substance acetanilide. Subsequently, the adsorption of the test substance is strong and the log Koc is considered to be higher than 5.63).
log Koc
8.1 dimensionless
Remarks on result:
other: value was extrapolated from the linear equation resulted from the reference substances
Details on results (HPLC method):
The test substance revealed a very strong retention on the column and its log Koc was even higher than that of the reference substance DDT with the highest log Koc of 5.63. Therefore, the log Koc of the test substance is considered to be more than 5.63.

Transformation products:

Table 1: Results of the reference substance under acidic conditions.

Reference substance mean tr (min)  k lgk logKoc
Thiourea  0.662 - - -
Acetanilide  0.779 0.177 -0.752 1.25
Linuron 0.977 0.476 -0 .322 2.59
Naphthalene 1.03 0.556 -0.255 2.75
1,2,3-Trichlorobenzene 1.11 0.677 -0.169 3.16
Diclofop-methyl  1.27 0.918 -0.0372 4.2
DDT 1.66 1.51 0.17 5.63

Linear equation obtained from the reference substances: log Koc=4.6570 1og K + 4.3230 (R^2 = 0.9293)

Description of key information

Log Koc = 8.10 (extrapolated) (OECD 121)

Key value for chemical safety assessment

Additional information

The adsorption coefficient Koc of the test substance was determined according to the OECD 121 and GLP (Jing, 2014). None of the tested reference substances had a log Koc above the tested item as required by the guideline, due to the very high retention of the tested substance on the column. The highest log Koc of the reference substances used was that of DDT with 5.63. The linear equation obtained from the reference substances was log Koc = 4.6570 log K + 4.3230 (R^2 = 0.9293). On this basis, the log Koc of the test substance was extrapolated and calculated to be 8.10.