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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:
18 April 2016 - 21 April 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
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
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 (incl. QA statement)
Type of method:
HPLC estimation method
Media:
soil
Details on study design: HPLC method:
The mobile phase was not buffered. In the absence of any relevant dissociating functional groups, no specific manipulation of the mobile phase pH was necessary to achieve an unionized form of the test item.

HPLC CONDITIONS
- HPLC System: Agilent Technologies 1100 series, incorporating autosampler and workstation
- Column: Waters XSelect CN 5 μm (150 x 4.6 mm id)
- Column temperature: 40°C
- Mobile phase: 55/45 (v/v) methanol/water
- pH of mobile phase: 6.4
- Flow-rate: 1.0 mL/min
- Injection volume: 10 μL
- UV detection (deadtime and references): 210 nm
- UV detection (test item): 290 nm

UNRETAINED SUBSTANCE
- Formamide; dissolved in 55/45 (v/v) methanol/water (648 mg/L)

REFERENCE SUBSTANCES
- 13 Reference substances in the log Koc range of 1.26 - 5.63: see the table in the result section.
- Stock solutions of the reference substances at concentrations of 100 - 163 mg/L in methanol were used.

TEST SUBSTANCE
An amount of 0.2574 g was diluted to 100 mL with methanol to give a concentration of 2.57E03 mg/L.

PERFORMANCE OF THE TEST
Solutions of the unretained substance, the reference substances and the test substance were injected in duplicate.

DATA HANDLING
- Dead time (t0) was the mean retention time of the unretained substance (n=2).
- Using the mean retention time, the capacity factor (k') was calculated for each reference substance: k'= (tr-t0)/t0
where tr = mean retention time and t0=mean dead time
- Log k’ values of the references substances were plotted against the log Koc values (see table below).
- Linear regression analysis was used to calculate the regression line.
- Regression line: log k’ = 0.3316 x log Koc– 0.7347 (r^2=0.9315, n=13)
- The capacity factors (k') of the test substance were calculated from the retention times (tr) and the mean dead time (t0): k'= (tr-t0)/t0
- Log Koc of the test substance was estimated by substituting the log k’ in the regression line
- The values of log Koc calculated from the individual test substance retention times were within a range of ± 0.25 log unit.
Key result
Type:
log Koc
Value:
3.76 dimensionless
Temp.:
20 °C
Remarks on result:
other: Koc=5.78E03 L/kg
Details on results (HPLC method):
In the HPLC chromatogram of the test substance solution, one test substance peak was observed.

Table: Results HPLC method for adsorption coefficient

Substance

Retention time (mins)

Mean retention time (mins)

Capacity factor (k’)

Log k’

Log Koc*

Injection 1

Injection 2

Formamide

1.895

1.890

1.893

 

 

 

 

 

 

 

 

 

 

Acetanilide

2.551

2.551

2.551

0.348

-0.459

1.25

Phenol

2.459

2.459

2.459

0.299

-0.524

1.32

Atrazine

3.479

3.479

3.479

0.838

-7.66 x 10-2

1.81

Isoproturon

3.698

3.698

3.698

0.954

-2.05 x 10-2

1.86

Triadimenol

4.927

4.932

4.930

1.605

0.205

2.40

Linuron

5.049

5.053

5.051

1.669

0.222

2.59

Naphthalene

4.422

4.427

4.424

1.338

0.126

2.75

Endosulfan-diol

6.268

6.268

6.268

2.312

0.364

3.02

Fenthion

7.250

7.259

7.255

2.833

0.452

3.31

α-Endosulfan

10.457

10.432

10.445

4.519

0.655

4.09

Phenanthrene

8.047

8.052

8.049

3.253

0.512

4.09

Diclofop-methyl

11.045

11.054

11.050

4.838

0.685

4.20

DDT

21.482

21.487

21.484

10.352

1.02

5.63

 

 

 

 

 

 

 

Fleuramone

8.056

8.056

0.326

0.326

0.513

0.513

3.76

3.76

*Log Koc values of the reference substances according to OECD 121 are based on soil adsorption data.

Validity criteria fulfilled:
yes
Remarks:
(the log Koc values derived from the individual measurements are within a range of 0.25 log unit)
Conclusions:
Using the HPLC method and soil-adsorption-reference data, the log Koc of the substance was estimated to be 3.76.
Executive summary:

The HPLC estimation method was applied for the determination of the adsorption coefficient (Koc) of the substance. The study was performed according to EC C.19 and OECD 121 and GLP. The mobile phase was 55/45 (v/v) methanol/water. In the HPLC chromatogram of the test substance solution, at 290 nm one test substance peak was observed. Using soil-adsorption-reference data, the log Koc value for the substance was estimated to be 3.76 (Koc= 5.78E03).

Description of key information

The HPLC estimation method was applied for the determination of the adsorption coefficient (Koc) of the substance. The study was performed according to EC C.19 and OECD 121 and GLP. The mobile phase was 55/45 (v/v) methanol/water. In the HPLC chromatogram of the test substance solution, at 290 nm one test substance peak was observed. Using soil-adsorption-reference data, the log Koc value for the substance was estimated to be 3.76 (Koc= 5.78E03).

Key value for chemical safety assessment

Koc at 20 °C:
5 780

Additional information

[LogKoc: 3.76]

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