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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22 May 2018
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:
2001
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
not specified
Test temperature:
25 ± 1 °C
Details on study design: HPLC method:
HPLC CONDITIONS
- Instrument: High-performance liquid chromatograph (No. LC-138) LC-2010CHT (Built-in ultraviolet and visible spectrophotometer) (Shimadzu).
- Differential refractive index detector: RI-104 (SHOWA DENKO).
- Column: Inertsil CN-3 (150 mm x 2.1 mm I.D., particle size 5 μm, GL Sciences)
- Column temperature: 25 °C
- Eluent: Methanol/purified water (1/1 v/v)
- Flow rate: 0.2 mL/min
- Injection volume: 2 µL

REFERENCE SUBSTANCES
- Formamide (for dead time)
- Acetanilide
- Atrazine
- Linuron
- Naphthalene
- Fenthion
- Phenanthrene

TEST PROCEDURES
- Preparation of test material solution: The test material (50.6 mg) was weighed with an electronic analytical balance and then filled up to 10 mL with methanol to prepare 5060 mg/L stock solution of the test material. The stock solution was diluted with the eluent for HPLC analysis to prepare 1010 mg/L test material solution. Methanol (1 mL) was pipetted into a 5-mL volumetric flask and filled up with the eluent to prepare a solvent blank.

- Measurement of retention times for reference materials, and making of regression line: The reference material solution and the formamide solution for dead time were injected twice to the test equipment, and then the retention times of reference materials were measured. The capacity factors (k) of reference materials were calculated by the following equation. A regression line was made by the method of least squares using the adsorption coefficient log Koc) and the logarithmic values of the capacity factors for reference materials. The capacity factor (k), the slope of regression equation (a) and the intercept of regression equation (b) were rounded off to three decimal places.

k = (tR – t0) / t0

tR: Retention time of reference material (min)
to: Dead time (min) (average of two measured values)

log Koc = a x log k + b

a: Slope of regression equation
b: Intercept of regression equation

- Measurement of retention time for test material: The test material solution was injected to the test equipment and the retention time of the test material was measured twice. Two peaks were detected from the test material solution, and those peaks were targeted for analysis. Each peak was named as Peak 1 to Peak 2 in order of the retention time. The solvent blank was injected once to the test equipment. It was confirmed that no peak existed at the peak position of test material by the analysis of solvent blank.

- Injection order: The reference material solution and the formamide solution were injected before and after the injection of test material solution to confirm that the retention times of reference materials do not change.
Injection order:
Reference material solution (first time) → Formamide solution (first time) → Test material solution (first time) → Test material solution (second time) → Solvent blank → Reference material solution (second time) → Formamide solution (second time).

- Calculation of adsorption coefficient: The capacity factor was calculated from the retention time of test material. The adsorption coefficient of test material was then calculated using the regression equation of regression line and was given as the average value of two measured values.

- Treatment of numerical values: The adsorption coefficient was represented as logarithm and rounded off to two decimal places. Values are treated in accordance with Japanese Industrial Standards (JIS) Z 8401: 1999 rule B.
Key result
Sample No.:
#1
Type:
log Koc
Value:
2.2 dimensionless
Temp.:
25 °C
Matrix:
Soil and Sewage Sludge
Remarks on result:
other: Peak 1
Key result
Sample No.:
#2
Type:
log Koc
Value:
2.3 dimensionless
Temp.:
25 °C
Matrix:
Soil and Sewage Sludge
Remarks on result:
other: Peak 2
Details on results (HPLC method):
It is judged that the test results are valid because the difference between two measured values was less than 0.25.

Table 2: Adsorption Coefficient of the Test Material

Peak No.

log Koc

Measured Value

Average

1

2.20

2.20

2.20

2

2.30

2.30

2.30

Table 3: Calculation Table

Material

tR

k

log k

log Koc

log Koc Ave.

Reference Material

Formamide (a)

2.19

t0 = 2.19

Formamide (b)

2.19

Acetanilide (a)

3.21

0.466

-0.332

1.25

 

Acetanilide (b)

3.21

0.466

-0.332

1.25

Atrazine (a)

4.04

0.845

-0.073

1.81

Atrazine (b)

4.03

0.840

-0.076

1.81

Linuron (a)

7.35

2.356

0.372

2.59

Linuron (b)

7.35

2.356

0.372

2.59

Naphthalene (a)

9.98

3557

0.551

2.75

Naphthalene (b)

9.98

3.557

0.551

2.75

Fenthion (a)

13.10

4.982

0.697

3.31

Fenthion (b)

13.08

4.973

0.697

3.31

Phenanthrene (a)

24.14

10.023

1.001

4.09

(Phenanthrene b)

24.11

10.009

1.000

4.09

Test Material

Peak 1 (a)

5.33

1.434

0.156

2.20

2.20

Peak 1 (b)

5.33

1.434

0.156

2.20

Peak 2 (a)

5.70

1.603

0.205

2.30

2.30

Peak 2 (b)

5.70

1.603

0.205

2.30

 

k = (tR – t0) / t0

to: Dead time (min) (average of two measured values)

tR: Retention time (min)

 

log Koc = 2.035 x log k + 1.882

r= 0.990

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of this study, the adsorption coefficients of the test material components at 25 °C were log Koc 2.20 (Peak 1) and log Koc 2.30 (Peak 2).
Executive summary:

The adsorption coefficient of the test material was investigated in accordance with the standardised guideline OECD 121, under GLP conditions.

The adsorption coefficient was determined using the HPLC estimation method. The eluent used was Methanol/purified water (1/1 v/v) and the test was performed at 25 °C.

It is judged that the test results are valid because the difference between two measured values was less than 0.25.

Under the conditions of this study, the adsorption coefficients of the test material components at 25 °C were log Koc 2.20 (Peak 1) and log Koc 2.30 (Peak 2).

Description of key information

Under the conditions of this study, the adsorption coefficients of the test material components at 25 °C were log Koc 2.20 (Peak 1) and log Koc 2.30 (Peak 2).

Key value for chemical safety assessment

Koc at 20 °C:
177.6

Additional information

The adsorption coefficient of the test material was investigated in accordance with the standardised guideline OECD 121, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).


The adsorption coefficient was determined using the HPLC estimation method. The eluent used was Methanol/purified water (1/1 v/v) and the test was performed at 25 °C.


It is judged that the test results are valid because the difference between two measured values was less than 0.25.


Under the conditions of this study, the adsorption coefficients of the test material components at 25 °C were log Koc 2.20 (Peak 1) and log Koc 2.30 (Peak 2).


 


Based on a geomean log koc of 2.25, a koc of 177.6 is calculated.