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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
01 March - 21 July 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Reliability 1 is assigned because the study was conducted according to OECD TG 121 in compliance with GLP, without deviations that influence the quality of the results.
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
Specific details on test material used for the study:
Identification: FRET 11-0078
Appearance/physical state: clear, colorless liquid
Storage conditions: approximately 4 °C, in the dark
Radiolabelling:
no
Test temperature:
30°C
Details on study design: HPLC method:
The test system utilized a high performance liquid chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

Preparation of sample solution
Test item (0.1037 g) was diluted to 200 mL with acetonitrile to give a concentration of 519 mg/L

Preparation of dead time solution
The dead time was determined by measuring the retention time of formamide (purity 99.94%, 615 mg/L solution in methanol).

Determination of retention time
The sample, dead time and reference standard solutions were injected in duplicate using the following HPLC parameters:
HPLC System: Agilent Technologies 1200 Series, incorporating autosampler and workstation
Detector type: ultraviolet (UV) at 210 nm
Column: Xselect HSS Cyano 5 µm (150 x 4.6 mm id)
Column temperature: 30 ºC
Mobile phase: methanol: water (55:45 v/v)
pH of mobile phase: 5.8
Flow-rate: 1.0 mL/min
Injection volume: 10 µL

Calculation
Construction of calibration curve
A calibration curve was constructed from the retention time data of the dead time and reference standard solutions. The capacity factors (k') for the reference standards were calculated.

Adsorption coefficient of sample
The capacity factor was calculated using the equation below and the log10 Koc value determined with reference to the calibration curve.

Capacity factor
The capacity factor was determined using the equation below.
k' = (tr-t0)/t0
where:
k'= capacity factor
tr= retention time (min)
t0= dead time (min)
A correlation of log k' versus log Koc of the calibration standards was plotted using linear regression.

Adsorption Coefficient
The adsorption coefficient was calculated using the following equation.
Log10 Koc = (Log10 k' - A)/B

where:
Koc= adsorption coefficient
k'= capacity factor
A= intercept of the calibration curve
B= slope of the calibration curve

Key result
Type:
log Koc
Remarks:
Mean log Koc of injection #1 and #2
Value:
2.96 dimensionless
pH:
5.8
Temp.:
30 °C
Details on results (HPLC method):
Adsorption coefficient:
Overall log10 Koc: 2.96
Adsorption coefficient: 906

The method guidelines state that the measurement of adsorption coefficient should be carried out on substances in their ionized and unionized forms (where appropriate). However, the absence of any relevant dissociation constants negates this requirement for this test item and therefore a single determination was performed, at an approximately neutral pH, with the test item in an unionized form.

 Calibration

The retention times of the dead time and the retention times, capacity factors (k') and log10 Kocvalues for the reference standards are shown in the two following tables:

Dead time

Retention time (mins)

Mean retention time (mins)

Injection 1

Injection 2

Formamide

1.963

1.963

1.963

 

Standard

Retention time (mins)

Mean retention time (mins)

Capacity factor (k')

Log10k'

Log10Koc

Injection 1

Injection 2

Acetanilide

2.647

2.644

2.646

0.348

-0.458

1.25

Phenol

2.523

2.521

2.522

0.285

-0.545

1.32

Atrazine

3.615

3.610

3.612

0.841

-7.54 x 10-2

1.81

Isoproturon

3.831

3.831

3.831

0.952

-2.15 x 10-2

1.86

Triadimenol

5.041

5.046

5.044

1.570

0.196

2.40

Linuron

5.153

5.153

5.153

1.625

0.211

2.59

Naphthalene

4.495

4.493

4.494

1.290

0.111

2.75

Endosulfan-diol

6.271

6.262

6.266

2.193

0.341

3.02

Fenthion

7.523

7.535

7.529

2.836

0.453

3.31

a-Endosulfan

10.429

10.451

10.440

4.320

0.635

4.09

Diclofop-methyl

11.334

11.329

11.332

4.774

0.679

4.20

Phenanthrene

8.166

8.154

8.160

3.158

0.499

4.09

DDT

21.786

21.759

21.772

10.093

1.004

5.63

The retention times, capacity factor and log10Kocvalue determined for the sample are shown in the following table:

Injection

Retention time (mins)

Capacity factor (k')

Log10k'

Log10Koc

Mean
log10Koc

Adsorption Coefficient

1

5.342

1.72

0.236

2.96

2.96

906

2

5.342

1.72

0.236

2.96

Overall log10Koc: 2.96

Adsorption coefficient: 906

Validity criteria fulfilled:
yes
Conclusions:
Based on 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 log Koc for FRET 11-0078 was determined to be 2.96 (Koc = 906).

Executive summary:

The HPLC screening method was applied for the determination of the adsorption coefficient (Koc) of FRET 11 -0078. The mobile phase was 55/45 (v/v) methanol/water. The column temperature was 30°C. The log Koc value of the test substance was 2.96 (Koc = 906). The study was performed in accordance with EC C.19 and OECD 121 and according to the principles of GLP.

Description of key information

The HPLC screening method was applied for the determination of the adsorption coefficient (Koc) of FRET 11 -0078.The mobile phase was 55/45 (v/v) methanol/water. The column temperature was 30°C. The log Koc value of the test substance was 2.96 (Koc = 906).The study was performed in accordance with EC C.19 and OECD 121 and according to the principles of GLP.

Key value for chemical safety assessment

Koc at 20 °C:
906

Additional information

[LogKoc: 2.96]