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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
13 to 14 August 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP, carried out according to recognised guideline
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:
yes
Remarks:
see below
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:
yes
Remarks:
see below
Principles of method if other than guideline:
A minor deviation from the study plan was noted in the methodology as follows:

Concerning: Reference Substances

According to the Study Plan: Recommended reference substances: Acetanilide, Methyl benzoate, Atrazine, Isoproturon, Triazophos, Linuron, Naphthalene, Fenthion, Pyrazophos, α-Endosulfan

Deviation: Reference substances used for calibration: Acetanilide, Methyl benzoate, Atrazine, Linuron, Naphthalene, α-Endosulfan, DDT

Reason for this changes: technical reason

Presumed Effect on the Study: None
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC estimation method
Media:
other: HPLC media
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable.
Radiolabelling:
no
Test temperature:
25 deg C
Details on study design: HPLC method:
The method uses HPLC for estimation of the adsorption coefficient, Koc.
The dual composition of the stationary phase having polar and non-polar sites allows for interaction of polar and non-polar groups of a molecule in a similar way, as in the case for organic matter in soil or sewage sludge matrices. This enables the relationship between the retention time on the column and the adsorption coefficient on organic matter to be established.

APPARATUS
Stationary Phase: LiChrospher 100 CN 250 x 4 mm, 5µm HPLC Column
HPLC system: Merck-Hitachi LaChrom HPLC system:
D-7000 Interface, No.: 0811-181
L-7100 HPLC Pump, No. : 0823-059
L-7200 Autosampler, No.: 0606-021
L-7400 UV Detector, No.: 0928-058
655A-52 Column Oven, No.: 6211-016
L-7612 Degasser, No.: 012-05
Ultrasonic bath: Elmasonic S300H, ELMA, No.: 010890105
Balance: BP221S Sartorius, No.: 11809117
Water purification system: MILLIPORE, DIRECT Q3, FOMNO 7334I

HPLC Conditions:
Detector: UV at 261 nm (test item)
UV at 210 nm (reference substances)
Column: LiChrospher 100 CN 250 x 4 mm, 5µm No.: 540779-1
Mobil Phase: Methanol : Water = 55 : 45
Flow: 1 ml/min.
Injection volume: 20 µl
Temperature: 25 °C

REFERENCE SUBSTANCES
Seven chemicals for which log Koc has been reported were used to calibrate the elution time in units of log Koc.
Dead time, t0 was determined by the injection of sodium nitrate solution.

PERFORMANCE OF THE TEST
Preparation of the Test Solutions:
Reference substances were dissolved in methanol. Concentration of these stock solutions was about 1 mg/ml. These stock solutions were diluted with the mobile phase resulting in about 10 μg/ml solutions.
In case of Sodium nitrate and DDT the stock solutions were diluted with the mobile phase resulting in about 100 μg/ml solutions.
In case of the α-Endosulfan the stock solution was dissolved in eluent and this solution was analysed.
Reofos 65 was also dissolved in methanol. The concentration of this solution was 1 mg/ml. This stock solution was diluted with mobile phase resulting in about 10 μg/ml solutions.

Determination of the retention times:
Three series of the above reference solutions and the test item solution were measured alternately, with two replicate injections.
For the determination of t0 (t0 = retention time of the unretarded component) sodium nitrate solution was injected.
The retention times were determined.
Details on sampling:
Not applicable.
Details on matrix:
Not applicable.
Details on test conditions:
Not applicable.
Computational methods:
Not applicable.
Type:
log Koc
Remarks:
estimated
Value:
3.43
Temp.:
25 °C
Remarks on result:
other: based on peak 1
Type:
Koc
Remarks:
estimated
Value:
2 704
Temp.:
25 °C
Remarks on result:
other: based on peak 1
Type:
log Koc
Remarks:
estimated
Value:
3.93
Temp.:
25 °C
Remarks on result:
other: based on peak 2
Type:
Koc
Remarks:
estimated
Value:
8 569
Temp.:
25 °C
Remarks on result:
other: based on peak 2
Details on results (HPLC method):
The three calibration series and three test item series were measured alternately. The adsorption coefficient Koc was determined based on a calibration curve using 7 reference items.
The capacity factors k’ were calculated from the dead time and retention times of the reference substances. The log k’ data of the reference substances were plotted against their log Koc values. The resulting calibration curve and the respective data are given in Figure 1 (attached) and Table 2 (below), respectively The equation of the curve fitted to the calibration points is as follows:

log k' = 0.204 * log Koc- 0.276    (Rsq= 0.989)

The capacity factors k’ and log Koc for Reofos 65 were calculated based on the calibration data obtained with the reference substances.
The estimated log Koc (based on Peak 1) 3.43
The estimated Koc (based on Peak 1) 2704
The estimated log Koc (based on Peak 2) 3.93
The estimated Koc (based on Peak 2) 8569
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.
Details on results (Batch equilibrium method):
Not applicable.
Statistics:
Not applicable.

The three calibration series and three test item series were measured alternately. The adsorption coefficient Koc was determined based on a calibration curve using 7 reference items.

The capacity factors k’ were calculated from the dead time and retention times of the reference substances. The log k’ data of the reference substances were plotted against their log Koc values. The resulting calibration curve and the respective data are given in Figure 1 (attached) and Table 2 (below), respectively

The equation of the curve fitted to the calibration points is as follows:

log k' = 0.204 * log Koc- 0.276    (Rsq= 0.989)

Table 2:      Measured and calculated data of the reference substances and test item

Chemical name

log KOC

Retention time (min)

log k'

log Koc

Accuracy
log unit

Repeatability
DlogKOC, log unit

from OECD 121

Calculated

Calculated

Sodium nitrate

-

1.54

for determination of dead time

1.54

1.55

1.55

1.55

1.56

Mean

1.55

CV%

0

Acetanilide

1.25

3.03

-0.019

1.26

0.03

0.04

3.03

-0.019

1.26

3.04

-0.016

1.28

3.05

-0.013

1.29

3.06

-0.010

1.31

3.06

-0.010

1.31

Mean

3.05

-0.015

1.28

CV%

0.5

-

-

Methyl-benzoate

1.80

3.41

0.080

1.75

0.03

0.05

3.42

0.082

1.76

3.43

0.085

1.77

3.43

0.085

1.77

3.45

0.089

1.80

3.45

0.089

1.80

Mean

3.43

0.085

1.77

CV%

0.5

-

-

Atrazine

1.81

3.26

0.044

1.57

0.23

0.01

3.26

0.044

1.57

3.26

0.044

1.57

3.27

0.046

1.58

3.27

0.046

1.58

3.27

0.046

1.58

Mean

3.27

0.045

1.58

CV%

0.2

-

-

Table 2:      Measured and calculated data of the reference substances and test item (continued)

Chemical name

log KOC

Retention time (min)

log k'

log Koc

Accuracy
log unit

Repeatability
DlogKOC, log unit

from OECD 121

Calculated

Calculated

Linuron

2.59

4.44

0.271

2.69

0.13

0.06

4.44

0.271

2.69

4.48

0.277

2.72

4.48

0.277

2.72

4.51

0.282

2.74

4.52

0.283

2.75

Mean

4.48

0.277

2.72

CV%

0.8

-

-

Naphthalene

2.75

4.82

0.325

2.95

0.24

0.06

4.82

0.325

2.95

4.88

0.333

2.99

4.88

0.333

2.99

4.92

0.338

3.02

4.92

0.338

3.02

Mean

4.87

0.332

2.99

CV%

0.9

-

-

α-Endosulfan

4.09

6.67

0.520

3.91

0.15

0.07

6.67

0.520

3.91

6.76

0.527

3.94

6.77

0.528

3.95

6.83

0.533

3.97

6.83

0.533

3.97

Mean

6.76

0.527

3.94

CV%

1

-

-

DDT

5.63

12.79

0.861

5.58

0.01

0.10

12.80

0.861

5.58

13.14

0.874

5.65

13.15

0.875

5.65

13.34

0.882

5.68

13.35

0.882

5.69

Mean

13.10

0.873

5.64

CV%

2

-

-

Reofos 65

Peak 1

-

5.56

0.413

3.39

-

0.08

5.57

0.415

3.39

5.65

0.423

3.43

5.67

0.425

3.44

5.71

0.429

3.46

5.71

0.429

3.46

Mean

5.65

0.423

3.43

CV%

1

-

-

Reofos 65

Peak 2

-

6.62

0.515

3.89

-

0.08

6.62

0.515

3.89

6.74

0.525

3.94

6.76

0.527

3.94

6.82

0.532

3.97

6.82

0.532

3.97

Mean

6.73

0.525

3.93

CV%

1

-

-

The capacity factors k’ and logKocfor Reofos 65 were calculated based on the calibration data obtained with the reference substances.

The estimated log Koc (based on Peak 1) 3.43

The estimated Koc (based on Peak 1) 2704

The estimated log Koc (based on Peak 2) 3.93

The estimated Koc (based on Peak 2) 8569

Validity criteria fulfilled:
yes
Conclusions:
The capacity factors k’ and log Koc for Reofos 65 were calculated based on the calibration data obtained with the reference substances.

The estimated log Koc (based on Peak 1) 3.43
The estimated Koc (based on Peak 1) 2704
The estimated log Koc (based on Peak 2) 3.93
The estimated Koc (based on Peak 2) 8569
Executive summary:

In the course of this study the estimated adsorption coefficient (Koc) of Reofos 65 was determined using high performance liquid chromatography. The Log Koc value is considered to be within the range of 3.43 to 3.93. Based on these values the test substance is deemed to offer a moderate potential to adsorb to soil / sediment environmental compartments.

Description of key information

Potential for soil adsorption.

Key value for chemical safety assessment

Koc at 20 °C:
8 511

Additional information

In the course of this study the estimated adsorption coefficient (Koc) of Reofos 65 was determined using high performance liquid chromatography. The Log Koc value is considered to be within the range of 3.43 to 3.93. Based on these values the test substance is deemed to offer a moderate potential to adsorb to soil / sediment environmental compartments.

.

[LogKoc: 3.93]