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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:
June 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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))
Version / remarks:
2008
Deviations:
no
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))
Version / remarks:
2001
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC estimation method
Specific details on test material used for the study:
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material:
room temperature in the dark, over silica gel
- Stability under test conditions:
substance partially hydrolysed before injection into HPLC column
- Solubility and stability of the test substance in the solvent/vehicle:
Water soluble, filtered fraction after stirring for 24 h at 30 °C at 200 rpm plus 17 3/4 hours non-stirred at 20 °C; filtered through 0.45 µm filter and diluted to 90% using purified water (see below for details)

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
An aliquot (0.0512 g) of test item and 100 mL of purified water were added to a flask and shaken (200 rpm) at 30.0 ± 1.0 °C for 24 hours, followed by static equilibration at 20.0 ± 0.5 °C for 17 ¾ hours. On removal from the 20 °C water bath, the sample was a hazy, translucent solution, containing excess, undissolved test item. The sample was filtered through a Phenex PTFE 0.45μm membrane filter, and after filtration, the sample was a clear, colorless solution free from excess, undissolved test item. The solution was diluted to 90% using purified water.
Radiolabelling:
no
Details on study design: HPLC method:
EQUIPMENT
HPLC System : Agilent Technologies 1200, incorporating workstation and autosampler
Detector type : variable wavelength (VW)
Column: Eclipse XDB-CN 5μ (150 x 4.6 mm id)
Column temperature: 30 °C
VW detector wavelength: 210 nm

MOBILE PHASES
- Type: Acetonitrile: purified water (55:45 v/v)
- Experiments with additives carried out on separate columns: no
- pH: 6.9
- Flow-rate: 1.0 mL/min
- Injection volume: 10 μL-
- Solutes for dissolving test and reference substances:

DETERMINATION OF DEAD TIME
- Method: the dead time was determined by measuring the retention time of formamide (purity 99.6%) of a 588 mg/L solution in acetonitrile: purified water (55:45 v/v)

REFERENCE SUBSTANCES
- Identity: Acetanilide, phenol, atrazine, linuron, naphthalene, endosulfan-diol, fenthion, alpha-endosulfan, phenanthrene, diclofop-methyl and DDT. All substances were of analytical grade with purities of at least 97.5%; solutions of reference substances were prepared in methanol

REPETITIONS
- Number of determinations: 2
Key result
Sample No.:
#1
Type:
Koc
Value:
< 17.8 dimensionless
pH:
6.8
Key result
Sample No.:
#1
Type:
Koc
Value:
> 430 000 dimensionless
pH:
6.8
Details on results (HPLC method):
- Retention times of reference substances used for calibration:
- Details of fitted regression line (log k' vs. log Koc):
- Graph of regression line attached
- Average retention data for test substance:
Transformation products:
not measured
Validity criteria fulfilled:
yes
Conclusions:
The adsorption coefficient of partially hydrolysed test item was determined to be in the range less than 17.8 to greater than 4.3 x 10e5, log10 Koc in the range less than 1.25 to greater than 5.63, using the HPLC screening method. The values indicating a high mobility are consistent with the estimates reported for the hydrolysis product glycoluril.
Executive summary:

The adsorption coefficient of partially hydrolysed test item was determined to be in the range less than 17.8 to greater than 4.3 x 10e5, log10 Koc in the range less than 1.25 to greater than 5.63, using the HPLC screening method, designed to be compatible with Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001. The results would classify the test item as having a range of mobility from very high mobility to immobile.

Description of key information

The water soluble fraction (WSF) was tested in a GLP study using the HPLC screening method in accordance with current OECD and EU guidelines. The adsorption coefficient of partially hydrolysed test item was determined to be in the range of less than 17.8 to greater than 4.3 x 10e5, log10 Koc in the range less than 1.25 to greater than 5.63. The values indicating a high mobility are consistent with the estimates reported for the hydrolysis product glycoluril.

Key value for chemical safety assessment

Additional information