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Environmental fate & pathways

Adsorption / desorption

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Endpoint:
adsorption / desorption: screening
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
[further information is included as attachment to Iuclid section 13]

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the structural similarity between the source and the target substances. Their environmental properties are expected to be similar because of this structural similarity, on common physico-chemical properties and because they are anticipated to follow the same environmental fate.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Refer to the Test material section of the source and target records.

3. ANALOGUE APPROACH JUSTIFICATION
Based on structural similarity, and common physico-chemical properties between the source and target substances, no significant difference is anticipated between isomers for adsorption coefficient. In addition, isomers are non-differentiated in HPLC conditions. Hence, it's considered suitable and scientifically justified to read-across the data between the two substances to fill the adsorption endpoint in the present dossier.

4. DATA MATRIX
See attached document in Iuclid section 13
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Key result
Type:
log Koc
Value:
3.72 dimensionless
Temp.:
30 °C
Key result
Type:
Koc
Value:
5 250 dimensionless
Temp.:
30 °C
Validity criteria fulfilled:
not applicable
Conclusions:
Based on data available on the source substance (Koc = 5250; log Koc = 3.72), the target and the source substances are considered immobile in soils, according to P. J. McCall et al., 1980.
Executive summary:

The adsorption coefficient of the target substance has been determined by a study, performed on the source substance, according to the OECD Guideline No. 121 with GLP statement.

The experimental method uses HPLC for the estimation of the adsorption coefficient Koc in soil and sewage sludge. An analytical column Luna 5 µm was used, with a column temperature at 30°C. The mobile phase was methanol:reverse osmosis water (55:45 v/v), with a pH at 5.7. The test item was diluted with methanol. The dead time was determined by measuring the retention time of formamide, diluted in mobile phase. For the reference standards, Acetanilide and Phenol were prepared in mobile phase and the remaining 10 standards were dissolved in methanol. The test item solution, dead time and reference standards were injected individually two times.

In the present study, the reference items covered the range of log Koc 1.25 to 5.63.

Under the conditions of the test, the retention time of the test item was found at 5.407 min for the first injection and at 5.400 min for the second injection. The corresponding log Koc was 3.720 and 3.717 (mean of 3.72, Koc = 5250). According to this test, the conclusion is that the source and the target substances should be regarded as immobile in soils (according to P. J. McCall et al., 1980).

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 25 October 2011 to 08 November 2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
This study was performed according to OECD Guideline 121 with GLP certificate. 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
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
UK GLP (inspected on 19-21 July 2011 / signed on 31 August 2011)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Specific details on test material used for the study:
No additional information
Radiolabelling:
no
Test temperature:
Column temperature: 30°C
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: HPLC
- Type: Agilent Technologies 1200, incorporating workstation
- Type, material and dimension of analytical (guard) column: Luna 5 µm (150 x 4.6 mm id)
- Detection system: refractive index detector (polarity: positive; temperature: 35°C)

MOBILE PHASES
- Type: methanol:reverse osmosis water (55:45 v/v)
- Experiments with additives carried out on separate columns: no
- pH: 5.7
- Solutes for dissolving test and reference substances: in methanol or in mobile phase

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

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

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: Injection volume = 10 µL
- Quantity of reference substances: Injection volume = 10 µL
- Intervals of calibration: no data

REPETITIONS
- Number of determinations: 2

EVALUATION
- Calculation of capacity factors k': k' = (tr - t0)/ t0, which tr = retention time (min) and t0 = dead time (min)
- Calculation of retention times: with typical chromatograph
- Determination of the log Koc value: log Koc = (log k' - A) / B, which A = intercept of the calibration curve and B = slope of the calibration curve

Remarks: The method guideline states that the measurement of adsorption coefficient should be carried out on substances in their ionised and unionised forms. However, since the test item contained no ionisable functional groups this was not possible and testing was performed at approximately neutral pH.
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:
3.72 dimensionless
Temp.:
30 °C
Key result
Type:
Koc
Value:
5 250 dimensionless
Temp.:
30 °C
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): See calibration curve in "Illustration".
- Graph of regression line attached: yes
- Average retention data for test substance: See table 5.4.1/2 in "Any other information on results incl. tables".
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: Retention times of reference substances used for calibration

Standard

Retention time (mins)

Mean retention time (mins)

Capacity factor (k)

Log k

Log Koc

Injection 1

Injection 2

Formamide (dead time)

2.311

2.304

2.308

0

N/A

N/A

Acetanilide

2.750

2.743

2.747

0.190

-0.721

1.25

Phenol

2.700

2.693

2.696

0.168

-0.773

1.32

Isoproturon

3.204

3.197

3.200

0.387

-0.412

1.86

Triadimenol

3.377

3.370

3.373

0.462

-0.336

2.40

Linuron

3.679

3.686

3.683

0.596

-0.225

2.59

Naphthalene

4.363

4.349

4.356

0.888

-0.0518

2.75

Endosulfan-diol

3.701

3.708

3.704

0.605

-0.218

3.02

Fenthion

5.256

5.263

5.260

1.28

0.107

3.31

Alpha-endosulfan

6.070

6.034

6.052

1.62

0.210

4.09

Diclofop-methyl

6.516

6.509

6.512

1.82

0.261

4.20

Phenanthrene

6.487

6.487

6.487

1.81

0.258

4.09

DDT

14.890

14.904

14.897

5.46

0.737

5.63

Table 5.4.1/2: Retention data for test substance

Retention time (mins)

Mean retention time (mins)

Capacity factor (k)

Log k

Log Koc

Injection 1

Injection 2

5.407

5.400

5.404

1.34

0.128

3.72

Validity criteria fulfilled:
yes
Conclusions:
Koc = 5250; log Koc = 3.72.
This result indicates that the test item is environmentally immobile in soils (according to P. J. McCall et al., 1980).
Executive summary:

The determination of the adsorption coefficient of the test material was performed according to the OECD Guideline No. 121 with GLP statement.

The experimental method uses HPLC for the estimation of the adsorption coefficient Koc in soil and sewage sludge. An analytical column Luna 5 µm was used, with a column temperature at 30°C. The mobile phase was methanol:reverse osmosis water (55:45 v/v), with a pH at 5.7. The test item was diluted with methanol. The dead time was determined by measuring the retention time of formamide, diluted in mobile phase. For the reference standards, Acetanilide and Phenol were prepared in mobile phase and the remaining 10 standards were dissolved in methanol. The test item solution, dead time and reference standards were injected individually two times.

In the present study, the reference items covered the range of log Koc 1.25 to 5.63.

Under the conditions of the test, the retention time of the test item was found at 5.407 min for the first injection and at 5.400 min for the second injection. The corresponding log Koc was 3.720 and 3.717 (mean of 3.72, Koc = 5250). This result indicates that the test item is environmentally immobile in soils (according to P. J. McCall et al., 1980).

Description of key information

Read-across, OECD Guideline 121, GLP, key study, validity 1:

Log Koc = 3.72; Koc = 5250.

The substance is environmentally immobile in soils, according to P. J. McCall et al., 1980.

Key value for chemical safety assessment

Koc at 20 °C:
5 250

Additional information

To assess adsorption coefficient of the registered substance, (-)-(3aR,5aS,9aS,9bR)-3a,6,6,9a-Tetramethyldodecahydronaphtho[2,1 -b]furan, one key study is available.

This study (Harlan, 2012) was performed on a source substance, (±)-(3aR*,5aS*,9aS*,9bR*)-3a,6,6,9a-Tetramethyldodecahydronaphtho[2,1 -b]furan, according to OECD Guideline 121 with GLP statement. This substance is the racemic form of the registered/target substance, non-differentiated in HPLC conditions. Based on structural similarity and common physico-chemical properties between these isomers, this source substance is considered adequate for read-across purposes (see IUCLID section 13 for justification).

The experimental method uses HPLC for the estimation of the adsorption coefficient Koc in soil and sewage sludge. Under the conditions of the test, the retention time of the test substance was found at 5.407 min for the first injection and at 5.400 min for the second injection. The corresponding log Koc was 3.720 and 3.717 (mean of 3.72, Koc = 5250). According to this test, the conclusion is that the source and the target substances should be regarded as immobile in soils (according to P. J. McCall et al., 1980).

[LogKoc: 3.72]