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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
Study period:
30-03-2006 - 08-05-2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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:
Guideline 67/548/EEC
Deviations:
no
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))
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC estimation method
Media:
other: calibration of HPLC column using standards
Radiolabelling:
no
Test temperature:
The HPLC column is tempered at 25 °C.
Details on study design: HPLC method:
For the calibration the retention times of a series of substances with known adsorption coefficients were measured and a calibration graph was established. The adsorption coefficient of the test item was derived from its retention time and the calibration graph. Two series were injected. Each series included the calibration substances and the test item. The test item was injected in-between the series of the calibration substances.
Except for the detection wavelength the chromatographic conditions were the same for the determination of t0, the establishment of the calibration graph and the measurement of the test item.
The dead time marker was dissolved in methanol and diluted 0.1 to 1 in the mobile phase and injected as single standards twice. The calibration substances were dissolved in methanol and diluted 0.1 to 1 in the mobile phase and injected as single standards twice. The item was dissolved in methanol and diluted 0.75 to 1 with distilled water and injected as single sample twice.
Key result
Type:
log Koc
Value:
> 4.2 dimensionless
Temp.:
25 °C
Type:
Koc
Value:
> 15 849 L/kg
Temp.:
25 °C
Type:
log Koc
Remarks:
extrapolated value
Value:
7.36 dimensionless
Temp.:
25 °C
Type:
Koc
Remarks:
extrapolated value
Value:
22 908 676.5 L/kg
Temp.:
25 °C
Details on results (HPLC method):
The retention time of the test item was compared with a calibration/regression curve obtained by the measurement of 7 standard chemicals. The retention time of the test item was 3.1 min. Comparing with the regression, a log Koc of 7.36 was calculated. However, this log Koc was above the highest standard chemical which had a log Koc of 4.2. Therefore, a log Koc of > 4.2 is considered for the test item.

The adsorption coefficient of the test item was found to be: log Koc >4.20

Table 1: Determination of the Dead Time to

Dead time
marker

tR in min
1st Measurement

tR in min
2nd Measurement

tR in min
Mean

Formamide

3.109

3.109

3.109

Dead time: t0 = 3.109 min

Table 2: Calibration Data – 1st Measurement
(*from OECD guideline 121, adopted January 2001)

Calibration substance

1st lnj. tR
in min

k

log k

log Koc*

Acetanilide

3.441

0.11

-0.97

1.25

Atrazin

3.517

0.13

-0.88

1.81

Monuron

3.637

0.17

-0.77

1.99

Triadimenol

3.684

0.18

-0.73

2.40

Linuron

3.913

0.26

-0.59

2.59

Pyrazophos

4.317

0.39

-0.41

3.65

Diclofop-methyl

4.399

0.41

-0.38

4.20

Regression: log Koc = a + b x log k

Parameters: a = 5.60
b = 4.50
r2 = 0.9523

Table 3: log Koc of the Test Item – 1st Measurement

Test Item

1st Inj. tR in min

k

Log k

log Koc

Test item

10.839

2.49

0.40

7.38
>4.20*

* beyond log Koc value of the highest calibration substance (Diclofop-methyl)

Table 4: Calibration Data – 2nd Measurement

(* from OECD guideline 121, adopted January 2001)

Calibration substance

2nd Inj. tR
in min

k

log k

log Koc*

Acetanilide

3.443

0.11

-0.97

1.25

Atrazin

3.516

0.13

-0.88

1.81

Monuron

3.637

0.17

-0.77

1.99

Triadimenol

3.684

0.18

-0.73

2.40

Linuron

3.916

0.26

-0.59

2.59

Pyrazophos

4.317

0.39

-0.41

3.65

Diclofop-methyl

4.399

0.41

-0.38

4.20

Regression: log Koc = a + b x log k

Parameters: a = 5.60
b = 4.50
r2 = 0.9513

Table 5: log Koc of the Test Item – 2nd Measurement

Test Item

2nd lnj. tR in min

k

Log k

log Koc

Test item

10.669

2.43

0.39

7.34
>4.20*

* beyond log Koc value of the highest calibration substance (Diclofop-methyl)


Table 6: log Koc of the Test Item

 

log Koc

1st Measurement

7.38
>4.20

2nd Measurement

7.34
>4.20

Mean

7.36
>4.20

 

Conclusions:
The log Koc of the test item was determined to be > 4.2.
Executive summary:

The adsorption/desorption of the test item was determined according to EU-method C.19 and OECD 121 using the HPLC method. The retention time of the test item was compared with a calibration/regression curve obtained by the measurement of 7 standard chemicals. The retention time of the test item was 3.1 min. Comparing with the regression, a log Koc of 7.36 was calculated. However, this log Koc was above the highest standard chemical which had a log Koc of 4.2. Therefore, a log Koc of > 4.2 is considered for the test item.

Description of key information

The log Koc of the test item was determined to be > 4.2. The Koc was calculated to be 15849 L/kg.

Key value for chemical safety assessment

Koc at 20 °C:
15 849

Additional information

The adsorption/desorption of the test item was determined according to EU-method C.19 and OECD 121 using the HPLC method. The retention time of the test item was compared with a calibration/regression curve obtained by the measurement of 7 standard chemicals. The retention time of the test item was 3.1 min. Comparing with the regression, a log Koc of 7.36 was calculated. However, this log Koc was above the highest standard chemical which had a log Koc of 4.2. Therefore, a log Koc of > 4.2 is considered for the test item (reference 5.4.1-1).