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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:
September 28, 2016 - October 20, 2016
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
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:
Commission Regulation (EC) No.440/2008
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:
The log Koc of the test item was estimated using HPLC method. Based on calibration curves obtained by correlation of the retention time of heterogeneous reference items with their known adsorption coefficient, the log Koc of the test was estimated.
Using methanol/water no test item related signal was observed. Thus acetonitrile / water mixture was used in a second experiment.
Each reference item was injected separately to the HPLC system to determine the individual retention time of the compounds under test conditions. Subsequently a mixed solution of the reference items was injected three times and the inert compound was injected twice. Thereafter, the test item was injected at least in triplicate. After the analysis of the test item solution the mixed solution of the reference compounds was injected once again.
Key result
Type:
log Koc
Value:
> 4.2 dimensionless
Temp.:
25 °C
Type:
Koc
Value:
> 15 848.9 L/kg
Temp.:
25 °C
Type:
log Koc
Remarks:
extrapolated
Value:
7.2 dimensionless
Temp.:
25 °C
Type:
Koc
Remarks:
extrapolated
Value:
15 848 931.9 L/kg
Temp.:
25 °C
Details on results (HPLC method):
Based on the retention times the system independent capacity factors were calculated. Based on the capacity factor and on the calibration curved obtained by HPLC analysis, the log Koc of the test test item was calculated. log Koc (estimated): >> 4.2

The adsorption coefficient of the test item was found to be: log Koc >> 4.22

Table 1: Capacity factor k' and log Koc of the reference items (determined using HPLC-UV detection)

Item

Number of analysis

Retention time (min)

Capacity factor

Log k‘

Log Koc

Sodium nitrate (= dead time)

5

1.33

n.a.

n.a.

n.a.

Methyl benzoate

4

3.46

1.61

0.21

1.80

Pyrazophos

4

4.25

2.20

0.34

3.65

Acetanilide

4

3.02

1.27

0.11

1.25

Linuron

4

3.84

1.89

0.28

2.59

1,2,3 Trichlorobenzene

4

4.25

2.20

0.34

3.16

Diclofop-methyl

4

4.94

2.72

0.43

4.20

Table 2: Capacity factor k' and log Koc of test item (determined using HPLC-UV detection)

Test

Replicate No.

Retention time (min)

Capacity factor

Log k‘

Log Koc

 

1

8.567

5.45

0.74

7.2

 

2

8.547

5.44

0.74

7.2

 

3

8.510

5.41

0.73

7.1

Validity criteria fulfilled:
yes
Conclusions:
The log Koc of the test item was determined to be > 4.2. The extrapolated log Koc was determined to be 7.2.
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 present study estimated the log Koc of the test item using HPLC method. Based on calibration curves obtained by correlation of the retention time of 6 structurally heterogeneous reference items with their known adsorption coefficient, the log Koc of the test was estimated to be above 4.2.

Description of key information

The log Koc of the test was estimated to be above 4.2. The log Koc of the test item was determined to be > 4.2. The extrapolated log Koc was determined to be 7.2.

Key value for chemical safety assessment

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 present study estimated the log Koc of the test item using HPLC method. Based on calibration curves obtained by correlation of the retention time of 6 structurally heterogeneous reference items with their known adsorption coefficient, the log Koc of the test was estimated to be above 4.2.

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