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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 29 August 2012 to 02 October 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
This study was performed according to OECD Guideline 121 and EU Method C.19 with GLP statement. This study is well documented and all validity criteria were fulfilled. No deviations were observed.
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))
Deviations:
no
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))
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
UK GLP Compliance Programme (inspected on 10 July 2012 / signed on 30 Nov. 2012)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Test temperature:
30°C (Column temperature)
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: HPLC System
- Type: Agilent Technologies 1100, incorporating autosampler and workstation.
- Type, material and dimension of analytical (guard) column: Column = Xselect HSS cyano 5 µm (150 x 4.6 mm id)
- Detection system: UV detector wavelength (210 nm)

MOBILE PHASES
- Type: Methanol:water (55:45 v/v)
- pH: 5.4
- Solutes for dissolving test and reference substances: The test item and reference standards were prepared in methanol. The dead time solution was diluted in methanol:water (55:45 v/v).

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column (formamide, purity 99.94%)

REFERENCE SUBSTANCES
- Identity: Phenol, Atrazine, Isoproturon, Triadimenol, Linuron, Naphthalene, Endosulfan-diol, Fenthion, alpha-Endosulfan, Phenanthrene, Diclofop-methyl, DDT.

DETERMINATION OF RETENTION TIMES
- Quantity introduced in the column: Injection volume 10 µL; Flow rate 1.0 mL/min.

REPETITIONS
- Number of determinations: The sample, dead time and reference standard solutions were injected in duplicate.

EVALUATION
- Calculation of capacity factors k' = (tr - t0) / t0, which tr = retention time (min) and t0 = dead time (min).
- Determination of the log Koc value = (log k' - A) / B, which A = intercept of the calibration curve and B = slope of the calibration curve.
Details on sampling:
Not applicable
Details on matrix:
Not applicable
Details on test conditions:
Not applicable
Computational methods:
Not applicable
Key result
Type:
log Koc
Value:
> 3.51 - < 3.66 dimensionless
Temp.:
30 °C
Remarks on result:
other: The definitive test was a range based on two values as the test item contained 2 isomeric forms.
Key result
Type:
Koc
Value:
> 3 243 - < 4 603 L/kg
Temp.:
30 °C
Remarks on result:
other: The definitive test was a range based on two values as the test item contained 2 isomeric forms.
Details on results (HPLC method):
- Retention times of reference substances used for calibration: See table 5.4.1/1 in "Any other information on results incl. tables".
- Details of fitted regression line (log k' vs. log Koc): A = -0.489; B = 0.299; r²=0.979.
- Graph of regression line attached: Yes. See in "Illustration"
- Average retention data for test substance: See table 5.4.1/2 in "Any other information on results incl. tables".

The definitive test was a range based on two values as the test item contained 2 isomeric forms. The two peaks at approximately 6 and 8 minutes were considered to be impurities (see typical chromatography in "Attached background material").
Adsorption and desorption constants:
Not applicable
Recovery of test material:
Not applicable
Concentration of test substance at end of adsorption equilibration period:
Not applicable
Concentration of test substance at end of desorption equilibration period:
Not applicable
Transformation products:
not measured
Details on results (Batch equilibrium method):
Not applicable
Statistics:
Not applicable

Table 5.4.1/1: The retention times of the dead time and the reference times, capacity factors and log Koc values for the reference standards

Standard

Retenion time (mins)

Mean retention time (mins)

Capacity factor (k’)

Log k’

Log Koc

Injection 1

Injection 2

Formamide*

1.895

1.890

1.893

-

-

-

Phenol**

2.541

2.541

2.541

0.343

-0.465

1.32

Atrazine

3.756

3.756

3.756

0.985

-6.71 x 10-3

1.81

Isoproturon

4.067

4.067

4.067

1.149

6.03 x 10-2

1.86

Triadimenol

5.646

5.651

5.649

1.985

0.298

2.40

Linuron

5.816

5.821

5.819

2.075

0.317

2.59

Naphthalene

4.951

4.951

4.951

1.616

0.208

2.75

Endosulfan-diol

7.483

7.483

7.483

2.954

0.470

3.02

Fenthion

8.97

8.965

8.968

3.738

0.573

3.31

Apha-endosulfan

13.275

13.275

13.275

6.015

0.779

4.09

Diclofop-methyl

14.179

14.169

14.174

6.490

0.812

4.20

Phenanthrene

9.752

9.752

9.752

4.153

0.618

4.09

DDT

29.956

29.956

29.956

14.829

1.171

5.63

* Dead time

** Phenol was not used in the calibration curve, and hence to calculate the sample result, as it was considered to have poor correlation with respect to the other reference standards.

Table 5.4.1/2: The retention times, capacity factor and log Koc values determined for the sample

Peak

Injection number

Retention time (mins)

Capacity factor (k’)

Log k’

Log Koc

Mean log Koc

Adsorption coefficient

1

1

8.761

3.629

0.560

3.511

3.511

3243

2

8.761

3.629

0.560

3.511

2

1

9.519

4.030

0.605

3.663

3.663

4603

2

9.524

4.032

0.606

3.664

Percentage area normalization:

Peak 1 = 26.3 % (corresponding to cis isomer)

Peak 2 = 70.0 % (corresponding to trans isomer)

Total of 96.3%

Validity criteria fulfilled:
yes
Conclusions:
The adsorption coefficient (Koc) of the test substance has been determined to be in the range of 3 243 (log Koc = 3.51) to 4 603 (log Koc = 3.66), corresponding to cis and trans isomers respectively. The result indicates that the test item is environmentally slightly mobile in soils (according to P.J. McCall et al., 1980).
Executive summary:

This study was performed according to OECD Guideline 121 and EU Method C.19 with GLP statement, to assess the adsorption coefficient of the test substance. The test utilized a high performance liquid chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

As the slope of the calibration curve for the reference standards showed good first order correlation and as the retention times between duplicate injections for each solution was consistent, the HPLC method was considered valid for the determination of adsorption coefficient. Based on the chromatographic data, the test item was considered to be stable during the test procedure.

All validity criteria were fulfilled.

The adsorption coefficient (Koc) of the test substance has been determined to be in the range of 3 243 (log Koc = 3.51) to 4 603 (log Koc = 3.66), corresponding to cis and trans isomers. The two peaks at approximately 6 and 8 minutes were considered to be impurities.

The result indicates that the test item is environmentally slightly mobile in soils (according to P.J. McCall et al., 1980).

Description of key information

OECD Guideline 121, EU Method C.19, GLP, key study, validity 1:

Koc = 3 243 to 4 603 (mean of 3 923)

log Koc = 3.51 to 3.66 (mean of 3.59)

Slightly mobile in soils (according to P.J. McCall et al., 1980).

Key value for chemical safety assessment

Koc at 20 °C:
3 923

Additional information

One valid key study is available to assess the adsorption coefficient of the registered substance. This study was performed according to OECD Guideline 121 and EU Method C.19 with GLP statement. The test utilized a high performance liquid chromatograph (HPLC). A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

As the slope of the calibration curve for the reference standards showed good first order correlation and as the retention times between duplicate injections for each solution was consistent, the HPLC method was considered valid for the determination of adsorption coefficient. Based on the chromatographic data, the test item was considered to be stable during the test procedure.

All validity criteria were fulfilled.

The adsorption coefficient of the registered substance has been determined to be in the range of 3 243 to 4 603, corresponding to a log Koc comprised between 3.51 to 3.66, for 96.3% of the test item by percentage area normalization. The definitive result was a range based on two values as the test item contained two isomeric forms.

The result indicates that the substance is environmentally slightly mobile in soils (according to P.J. McCall et al., 1980).

[LogKoc: 3.59]