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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Experimental test result performed using standard test guidelines
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))
GLP compliance:
no
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Test temperature:
25°C
Details on study design: HPLC method:
HPLC Procedure:
The solutions of the test chemical and reference substances were prepared in acetonitrile. Each of the reference substances and test chemical were analysed by HPLC. The column was saturated with solvent (mobile phase) in isocratic mode on above chromatographic conditions mentioned. After 20 min of column saturation with mobile phase, sequential analysis of urea (for dead time: t0), reference substances and test chemical was performed on HPLC. All the HPLC runs were performed in duplicates. Retention time tR was measured to calculate the capacity factors k (mentioned in below equation), it was then converted in log to obtain log k. A standard curve between log k versus log Koc was plotted to obtain the value of log Koc of test chemical.
K= tR -t0
t0
where
k= capacity factor,
tR= retention time of test substance and reference substance.
t0=retention time of Urea.

Operating Conditions:
HPLC Model No. : Agilent Technologies,1260 Infinity
Flow Rate : 1.0ml/min
Column : ZORBAX Eclipse Plus C18, 4.6×100mm, 3.5 μm
Mobile phase : ACN : water (55:45)
Temperature : 25°C
Detector : Diode Array Detector @210nm
Injector : Autosampler
Injector volume : 20μl
Data Acquisition software : ChemStationOpen lab Control Panel
Analytical monitoring:
not specified
Key result
Sample No.:
#1
Type:
log Koc
Value:
2.787 dimensionless
pH:
7.4
Temp.:
25 °C
Remarks on result:
other: logKoc was reported to be 2.787±0.001
Details on results (HPLC method):
The Adsorption coefficient (KOC) on soil and on sewage sludge of the test chemical was determined to be 2.787±0.001 at 25°C
Transformation products:
not specified

Result:

Table: List of reference substances

Reference Substance

Tr1

Tr2

Mean tR± S.D.

K

Log K

Log Koc

Urea

2.087

2.087

2.087±0.000

NA

NA

NA

p-Toluamide

3.132

3.133

3.133±0.001

0.501

-0.3

1.8

Aniline

3.831

3.834

3.833±0.002

0.836

-0.078

2.1

N-methylaniline

4.438

4.452

4.445±0.010

1.13

0.053

2.2

4-Chloroaniline

4.044

4.047

4.046±0.002

0.938

-0.028

2.1

phenanthrene

6.05

6.06

6.055±0.007

1.901

0.279

2.5

Naphthalene

5.044

5.048

5.046±0.003

1.418

0.152

2.4

DDT

9.846

9.863

9.855±0.012

3.722

0.571

2.9

Table: Adsorption coefficient (logKoc) value of test chemical.

Test substance

K

Log k

Log Koc

 

Mean of Log Koc ± S.D.

 

Rt1

8.144

2.902

0.463

2.787

2.787±0.001

 

Rt2

8.159

2.909

0.464

2.788

 

Validity criteria fulfilled:
yes
Conclusions:
The Adsorption Coefficient of test chemiical was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was determined to be 2.787±0.001 at 25°C. Thus based on the result it is concluded that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.
Executive summary:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. The sample of test chemical was prepared by adding 10 mg in acetonitrile to prepare 1000 mg/L test solution, sonicated for 1 mins and filtered through 0.22 μm nylon syringe filter. pH of the resulting solution was 7.4. The analysis was performed at constant recommended conditions such as temperature 25°C (solvent: water) ratio 55:45 at the flow rate of 1 mL/min at 210 nm. The reference substances were chosen according to estimated Koc range of the test substance and generalize calibration graph was prepared. Selected reference substances and test chemical were prepared in acetonitrile with concentration of 400 mg/L. Both were analyzed on HPLC considering the similar conditions. After analyzing on above conditions calibration curve of selected reference substances was prepared to obtain log Koc value. The reference substances were p-Toluamide, Aniline, N-methylaniline, 4-Chloroaniline, phenanthrene, Naphthalene, DDT, having Koc value

ranging from 1.8 to 2.9. The Log Koc value was test chemical was determined to be 2.787±0.001 at 25°C. Thus, based on the result it is concluded that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

Description of key information

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals (Experimental study report, 2019). The solutions of the test substance and reference substances were prepared in appropriate solvents. The sample of test chemical was prepared by adding 10 mg in acetonitrile to prepare 1000 mg/L test solution, sonicated for 1 mins and filtered through 0.22 μm nylon syringe filter. pH of the resulting solution was 7.4. The analysis was performed at constant recommended conditions such as temperature 25°C (solvent: water) ratio 55:45 at the flow rate of 1 mL/min at 210 nm. The reference substances were chosen according to estimated Koc range of the test substance and generalize calibration graph was prepared. Selected reference substances and test chemical were prepared in acetonitrile with concentration of 400 mg/L. Both were analyzed on HPLC considering the similar conditions. After analyzing on above conditions calibration curve of selected reference substances was prepared to obtain log Koc value. The reference substances were p-Toluamide, Aniline, N-methylaniline, 4-Chloroaniline, phenanthrene, Naphthalene, DDT, having Koc value ranging from 1.8 to 2.9. The Log Koc value was test chemical was determined to be 2.787±0.001 at 25°C. Thus, based on the result it is concluded that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

Key value for chemical safety assessment

Koc at 20 °C:
612.35

Additional information

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals (Experimental study report, 2019). The solutions of the test substance and reference substances were prepared in appropriate solvents. The sample of test chemical was prepared by adding 10 mg in acetonitrile to prepare 1000 mg/L test solution, sonicated for 1 mins and filtered through 0.22 μm nylon syringe filter. pH of the resulting solution was 7.4. The analysis was performed at constant recommended conditions such as temperature 25°C (solvent: water) ratio 55:45 at the flow rate of 1 mL/min at 210 nm. The reference substances were chosen according to estimated Koc range of the test substance and generalize calibration graph was prepared. Selected reference substances and test chemical were prepared in acetonitrile with concentration of 400 mg/L. Both were analyzed on HPLC considering the similar conditions. After analyzing on above conditions calibration curve of selected reference substances was prepared to obtain log Koc value. The reference substances were p-Toluamide, Aniline, N-methylaniline, 4-Chloroaniline, phenanthrene, Naphthalene, DDT, having Koc value ranging from 1.8 to 2.9. The Log Koc value was test chemical was determined to be 2.787±0.001 at 25°C. Thus, based on the result it is concluded that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.