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Reference
Endpoint:
adsorption / desorption: screening
Remarks:
HPLC estimation method
Type of information:
experimental study
Adequacy of study:
key study
Study period:
8 July 2016 to 8 July 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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:
(version 2001)
Deviations:
no
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:
(version 2008)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC estimation method
Radiolabelling:
no
Test temperature:
25 ± 0.5 °C.
Details on study design: HPLC method:
TEST ITEM PREPARATION
20.1 mg test substance were weighed into a 10-mL flask and filled up to 10.05 mL with methanol. 25 μL of the resulting solution with a concentration of 2 g/L, were mixed with 525 μL Methanol and 450 μL water and used for measurement (final concentration 50 mg/L). The pH value of this solution was determined to be 6 - 7 using indicator paper.

TEST SYSTEM
High performance Liquid Chromatography (HPLC)
- Degasser: Agilent G1379A
- Quaternary pump: Agilent G1311A
Autosampler: Agilent G1313A
- Column compartment: Agilent G1316A
- UV Detector: Agilent MWD G1365B
- Software: ChromeleonTM, Version 6.80 SR11d Bulild 3302

HPLC METHOD PARAMETERS
- Eluent isocratic methanol/water 55/45 % (v/v), degassed.
- Flow rate: 0.8 mL/min
- Injection volume: 10 μL
- Column temperature: 25 ± 0.5 °C.
- Wavelenght for evaluation: 210 nm

PERFORMANCE OF THE STUDY
- Pre-test: A solution of the test item in eluent was prepared and injected in order to check detectability and to find an approximate range for log Koc. In the preliminary test, a solution of the test item with a concentration of 50 mg/L was injected in order to check retention time and the signal height. The first injection was run with pump mixed eluent (from pure methanol and pure water) which resulted in unacceptable resolution, most likely caused by air bubbles. For further measurements, pre-mixed eluent was used therefore. The solution gave one very large peak at 3.6 and a smaller one at 3.04 min. Based on this result, a suitable mix of reference items was chosen (with DDT as substance with the highest log Koc and a retention time of approx. 12.2 minutes). The 50 mg/L test item solution was also used for the determination of the log Koc of the test item.
- Determination of the Dead Time: The dead time t0 was measured by using an unretained compound (sodium nitrate) which was included in the mix of the reference items.
- Determination of the Log Koc: One vial was filled with the reference item mix and one vial with the test item solution. The vials were analysed using HPLC with the program described above. Three injections were measured from the reference item mix, three injections from the test item solution and again three injections from the reference item mix. The data was saved, the retention times of the six peaks of the reference item mix and the retention time of the peaks of the test item were used for further calculations.
- Calibration log k’ vs. log Koc: The calibration function was drawn up from the six measurements of the capacity factors of the reference items. By plotting the (known) log Koc values of the reference items against the mean log capacity factors and performing linear regression, a calibration function was obtained.
- Calculation of log Koc: With the calculated capacity factors for the test item, each log Koc from the three determinations was calculated. Finally, mean and standard deviation of the log Koc were calculated.
Key result
Type:
log Koc
Value:
1.83 dimensionless
pH:
7
Temp.:
25 °C
Remarks on result:
other: Peak 1
Key result
Type:
log Koc
Value:
2.36 dimensionless
pH:
7
Temp.:
25 °C
Remarks on result:
other: Peak 2
Details on results (HPLC method):
See 'Any other information on results and tables'.

Table: Retention times (RT) and capacity factors of reference items

Compound

RT mean*

(min)

RT

SD

(min)

RT relative SD

(%)

k’

Log k’

Log Koc

Sodium nitrate

1.050

0.025

2.4

0.0000

-

-

Phenol

2.638

0.002

0.1

1.5118

0.1795

1.32

Methylbenzoate

3.043

0.002

<0.1

1.8969

0.2781

1.80

Naphthalene

40.79

0.002

0.1

2.8836

0.4599

2.75

1,2,3-Trichlorobenzene

4.584

0.002

<0.1

3.3648

0.5270

3.16

Phenanthrene

6.315

0.006

0.1

5.0127

0.7001

4.09

DDT

12.166

0.007

0.1

10.5828

1.0246

5.63

* Determined from six injections

Table: Retention times test item:

Retention times test item

Peak 1

(min)

Peak 2

(min)

Measurement

3.035

3.573

Measurement

3.040

3.573

Measurement

3.045

3.573

Mean

3.040

3.573

SD

0.005

0.000

 

Table: Capacity factor, log capacity factor, and log Koc of the test item:

 

Peak 1

Peak 2

k’

Log k’

Log Koc

k’

Log k’

Log Koc

Measurement

1.8897

0.2764

1.83

2.4016

0.3805

2.36

Measurement

1.8943

0.2775

1.83

2.4018

0.3805

2.36

Measurement

1.8994

0.2786

1.84

2.4019

0.3806

2.36

Mean

-

-

1.83

-

-

2.36

SD

-

-

0.01

-

-

0.00

log Koc was calculated from the capacity factor as follows: log Koc = (log k’ + 0.0774) / 0.1938

Validity criteria fulfilled:
yes
Conclusions:
The log Koc of FRET 11-0571 ranges from 1.83 - 2.36 (two peaks).
Executive summary:

The adsorption potential of FRET 11 -0571 was investigated in a study according to OECD TG 121 (HPLC estimation method) and in compliance with GLP criteria (LAUS, 2016). In this study, six reference substances with known log Koc values and the test substance were analysed by HPLC. The log k’ values of reference substances were plotted against the known log Koc values. The log Koc value for the test substance was calculated by substituting its mean log k’ in the calibration curve. For the test item two peaks were found with log Koc values ranging from 1.83 to 2.36.

Description of key information

The log Koc ranges from 1.83 to 2.36 (two peaks). The mean value of 2.1 is used as key value for assessment.

Key value for chemical safety assessment

Koc at 20 °C:
126

Additional information

[LogKoc: 2.1]