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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 September 2017 to13 September 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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))
Version / remarks:
OECD Guideline for Testing of Chemicals No. 121., “Estimation of the Adsorption Coefficient (KOC) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC)” (Original Guideline, adopted 22 January 2001)
Deviations:
no
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))
Version / remarks:
Commission Regulation (EC) No 440/2008, Part C, C.19 “Estimation of the Adsorption Coefficient (KOC) on Soil and on Sewage Sludge Using High Performance Liquid Chromatography (HPLC)”, Official Journal of the European Union L 142 of 31 May 2008
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC estimation method
Media:
soil
Specific details on test material used for the study:
No further details specified in the study report.
Radiolabelling:
no
Test temperature:
25 °C
Details on study design: HPLC method:
PRINCIPLE OF THE TEST
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
HPLC system: Knauer Azura HPLC-UV
Balance: Sartorius BP221S
Ultrasonic bath: ELMA Elmasonic S300
Water purification system: Millipore, Direct-Q 8 UV
Refrigerator: Zanussi

HPLC Conditions:
Detector: UV at 225 and 254 nm
Column: LiChrospher 100 CN 250 × 4.6 mm, 5μm
Mobil Phase: Acetonitrile : ultrapure water = 6 : 4
Flow: 1 mL/min.
Injection volume: 10 μL
Temperature: 25 °C

REFERENCE SUBSTANCES
Six 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 and test item were dissolved in acetonitrile. Concentration of these stock solutions was about 1 mg/mL. These stock solutions were diluted with eluent resulting about 10 μg/mL solution.
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.
Key result
Type:
log Koc
Value:
> 5.63 dimensionless
Temp.:
25 °C
Remarks on result:
other: pH & % Org. carbon not specified
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 6 reference items.
The capacity factors 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 equation of the curve fitted to the calibration points is as follows:
log k = 0.0759 × log Koc + 0.136 (Rsq = 0.956)

Retention time measured for NAUGARD® XL-1 (6.42 min) is higher than the last eluting standard, DDT (6.34 min). This result shows that log Koc of NAUGARD® XL-1 is beyond the calibrated range.
The estimated log Koc is higher than 5.63.

Measured and calculated data of the reference substances

Chemical name

Log Koc

Retention time (min)

Log k

Log Koc

Repeatability ∆logKoc, log unit

Accuracy log unit

From OECD 121

Calculated

Calculated

Sodium nitrate

-

1.40

For determination of dead time

1.41

1.42

1.41

1.42

1.42

Mean

1.41

CV%

0.6

Acetanilide

1.25

3.61

0.192

0.74

0.03

0.50

3.61

0.192

0.74

3.62

0.193

0.76

3.61

0.192

0.74

3.62

0.193

0.76

3.61

0.192

0.74

Mean

3.61

0.192

0.75

CV%

0.1

-

-

Methyl benzoate

1.80

4.06

0.272

1.80

0.02

0.00

4.06

0.272

1.80

4.06

0.272

1.80

4.06

0.272

1.80

4.06

0.272

1.80

4.05

0.271

1.78

Mean

4.06

0.272

1.80

CV%

0.1

-

-

Triazophos

2.55

4.61

0.354

2.88

0.02

0.34

4.62

0.356

2.90

4.61

0.354

2.88

4.61

0.354

2.88

4.61

0.354

2.88

4.61

0.354

2.88

Mean

4.61

0.355

2.89

CV%

0.1

-

-

Naphthalene

2.75

4.69

0.365

3.03

0.02

0.27

4.69

0.365

3.03

1.68

0.364

3.01

4.69

0.365

3.03

4.69

0.365

3.03

4.68

0.364

3.01

Mean

4.69

0.365

3.02

CV%

0.1

-

-

Fenthion

3.31

4.96

0.400

3.48

0.03

0.17

4.96

0.400

3.48

4.95

0.398

3.46

4.96

0.400

3.48

4.97

0.401

3.50

4.96

0.400

3.48

Mean

4.96

0.400

3.48

CV%

0.1

-

-

DDT

5.63

6.34

0.542

5.36

0.01

0.27

6.34

0.542

5.36

6.34

0.542

5.36

6.34

0.542

5.36

6.34

0.542

5.36

6.34

0.542

5.36

Mean

6.34

0.542

5.36

CV%

0.1

-

-

 

Measured and calculated data of the test item

Test item

 

Retention time (min)

Log k

Log Koc

Repeatability ∆logKoc, log unit

Calculated

Calculated

NAUGARD® XL-1

-

6.41

-

-

-

6.42

-

-

6.42

-

-

6.42

-

-

6.42

-

-

6.42

-

-

Mean

6.42

-

-

CV%

0.14

-

-

Conf. interval

-

-

-

 

Validity criteria fulfilled:
yes
Conclusions:
Retention time measured for NAUGARD® XL-1 (6.42 min) is higher than the last eluting standard, DDT (6.34 min). This result shows that log Koc of NAUGARD® XL-1 is beyond the calibrated range.
The estimated log Koc is higher than 5.63.
Executive summary:

In the course of this study the adsorption coefficient (Koc) of NAUGARD® XL-1 was estimated using high performance liquid chromatography.

The estimated log Koc is higher than 5.63

Description of key information

The estimated log Koc is higher than 5.63

Key value for chemical safety assessment

Koc at 20 °C:
426 580

Additional information

In the course of this study the adsorption coefficient (Koc) of NAUGARD® XL-1 was estimated using high performance liquid chromatography.

The estimated log Koc is higher than 5.63

[LogKoc: 5.63]

[LogKoc: 5.63]

[LogKoc: 5.63]