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Adsorption / desorption

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Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 to 15 August 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: guideline study under GLP
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))
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))
Principles of method if other than guideline:
adsorption coefficient should be carried out on substances in their ionized and unionized forms, where applicable. However, the dissociation constants of certain functional groups found in the test item made it impossible to satisfy this criterion; for some of the test item constituents, testing would be required at pH 12 or greater.
As a consequence of this, for some constituents one of the functional groups will always be present in its ionized form. Therefore, as pH 12 or above is outside the environmentally relevant pH range for this test and also experimentally impractical, testing was carried out at approximately neutral pH.
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC estimation method
Details on study design: HPLC method:
EHPLC System : Agilent Technologies 1200 incorporating workstation
Column : XSelect HSS CN (150 x 4.6 mm id)
Column temperature : 30 ºC
Mobile phase : Methanol:purified water (55:45 v/v)*
pH of mobile phase : 7.0
Flow-rate : 1.0 mL/min
Injection volume : 10 μl
UV detector wavelength : Dead Time and Reference Standards: 210 nm
ELS detector : Sample:
Nebulizer temperature: 70 °C
Evaporator temperature 80 °C
Gas flow: 1 L/min

DETERMINATION OF DEAD TIME
- Method: by inert substance (formamide [purity* 99.94%, 604 mg/L solution in methanol:purified water (55:45 v/v)]) which is not retained by the column
- Dead time: retention 1.978 min

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



Type:
log Koc
Value:
> 5.63
Remarks on result:
other: retention time of all substance peaks > 30 min
Details on results (HPLC method):
- Retention times of reference substances used for calibration: see table
- Details of fitted regression line:
Correlation coefficients (r): 0.921
Slope: 0.344
Intercept: 0.752
- Average retention data for test substance: > 30 min

Standard

Retention Time (mins)

Retention Time (mins) Mean

Capacity Factor (k)

Log10 k

Log10 Koc

 

Injection 1

Injection 2

 

 

 

 

Acetanilide

2.721

2.721

2.721

0.376

-0.425

1.25

Atrazine

3.790

3.790

3.790

0.916

-0.038

1.81

Isoproturon

4.048

4.048

4.048

1.05

0.020

1.86

Aniline

2.551

2.556

2.554

0.291

-0.536

2.07

Triadimenol

5.569

5.569

5.569

1.82

0.259

2.40

Linuron

5.578

5.578

5.578

1.82

0.260

2.59

Naphthalene

4.801

4.806

4.804

1.43

0.155

2.75

Endosulfan-diol

6.876

6.871

6.874

2.48

0.394

3.02

Fenthion

8.397

8.392

8.395

3.24

0.511

3.31

α-Endosulfan

11.822

11.822

11.822

4.98

0.697

4.09

Diclofop-methyl

12.891

12.896

12.894

5.52

0.742

4.20

Phenanthrene

9.106

9.116

9.111

3.61

0.557

4.09

DDT

25.933

25.962

25.948

12.1

1.08

5.63

 

Validity criteria fulfilled:
yes
Conclusions:
The logKoc of the substance is > 5.63
Executive summary:

A determination of the Koc of the substance using the HPLC method gave a value of the logKoc of > 5.63 (the retention time of all peaks was > 30 min). Elution was only possible after increasing the mobile phase to 100% methanol (after elution of DDT)

Endpoint:
adsorption / desorption
Remarks:
other: QSAR
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Standard QSAR used in a worst case approach. Validation information on QSAR available
Justification for type of information:
calculation with KOCWIN (v2.00) performed with representative components
Qualifier:
no guideline followed
Principles of method if other than guideline:
calculation with KOCWIN (v2.00) performed with representative components
GLP compliance:
no
Type:
log Koc
Value:
>= 5.5 - <= 6.7

see attachment

Conclusions:
The calculated logKoc is 5.5-6.7
Executive summary:

The Koc has been calculated by the QSAR based on MCI included in the KOCWIN model (vs 2.00) and is calculated to be between 5.5 and 6.7.

Endpoint:
adsorption / desorption
Remarks:
other: QSAR
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Standard QSAR used in a worst case approach. Validation information on QSAR available
Justification for type of information:
calculation with KOCWIN (v2.00) performed with representative components
Qualifier:
no guideline followed
Principles of method if other than guideline:
calculation with KOCWIN (v2.00) performed with representative components
GLP compliance:
no
Type:
log Koc
Value:
>= 5 - <= 5.7

see attachment

Conclusions:
The calculated logKoc is 5.0-5.7
Executive summary:

The Koc has been calculated by the QSAR based on logPow included in the KOCWIN model (vs 2.00) and is calculated to be between 5.0 and 5.7.

Description of key information

The experimental value for the logKoc is > 5.63. The substance is surface active and QSAR predictions show very high values (>6.7).

Key value for chemical safety assessment

Koc at 20 °C:
1 000 000

Additional information

For risk assessment the Koc will be set to the maximum value (indicated in EUSES) that will lead to reliable exposure assessment. This value is indicated as the key value above.

[LogKoc: 6.0]