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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:
From 14/10/2011 to 17/10/2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
This study was performed according to OECD Guideline 121 with GLP statement. All validity criteria were fulfilled. However, as a non specific detector was used, no guarantee about respective proportions of components is be provided, nor attempt of identification of peaks.
Reason / purpose:
reference to same study
Reason / purpose:
reference to other 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))
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
2011-03-07
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Water solubility: < 1 mg/L according to SDS
- Density at 20°C: 932 Kg/m^3
Radiolabelling:
no
Test temperature:
The temperature during the analytical sequence was 30°C.
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: Agilent HPLC pump
- Type, material and dimension of analytical (guard) column: Agilent Zorbax CN, particule size = 5 µm, mobile phase = methanol-water 55-45 v/v pH 7.5 at 30°C, flow rate = 0.25 mL/min, injected volume = 5 µL, length = 15 cm, internal diameter = 2.1 mm, wavelength analysis = 210 nm.
- Detection system: UV visible detector (210 nm)

MOBILE PHASES
- Type: methanol-water 55-45 v/v
- pH: 7.5 at 30°C
- Solutes for dissolving test and reference substances: methanol

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column (formamide)

REFERENCE SUBSTANCES
- Identity: Formamide, Acetanilide, Methyl benzoate, Triadimenol, Naphtalene, Phenanthrene, 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane.

DETERMINATION OF RETENTION TIMES
- Injected volume: 5 µL.
- Injection sequence: mixture of the analytical reference items (3 times), blank methanol, test item (3 times).

REPETITIONS
- Number of determinations: 3

EVALUATION
- Calculation of capacity factors k': k'=(tr-t0)/t0 where tr = HPLC retention time of test and reference substance (minutes), t0 = HPLC dead time (minutes).
- Determination of the log Koc value: log Koc = a + b x log k' where the a and b regression coefficients are obtained by linearly regressing the log of partition coefficients of reference substances against the log of capacity factors of the same substances.
Details on sampling:
Not applicable
Details on matrix:
Not applicable
Details on test conditions:
Not applicable
Computational methods:
Not applicable
Type:
log Koc
Value:
3.3
Temp.:
30 °C
Remarks on result:
other: 3.30; 3.31; 3.30 (3 determinations)
Details on results (HPLC method):
- Retention times of reference substances used for calibration: See table 5.4.1/1 in "Any other information on results incl. tables".
- Details of fitted regression line (log k' vs. log Koc): log Koc = 3.1585 log k' + 2.8625 with R² = 0.9753
- Graph of regression line attached and chromatograms : See in "Attached background material"
- Average retention data for test substance: 4.42 min (4.42; 4.43; 4.42 minutes, for the 3 determinations). See table 5.4.1/2 in "Any other information on results incl. tables")
Adsorption and desorption constants:
Not applicable
Recovery of test material:
Not applicable
Concentration of test substance at end of adsorption equilibration period:
Not applicable
Concentration of test substance at end of desorption equilibration period:
Not applicable
Details on results (Batch equilibrium method):
Not applicable
Statistics:
Not applicable

Table 5.4.1/1: Results for the reference substances

Products

Mean retention time (min)

Value of log k’

Value of log Koc

Formamide

1.86

-

-

Acetanilide

2.31

-0.61630043

1.25

Methyl benzoate

2.76

-0.31527043

1.80

Triadimenol

3.36

-0.09342169

2.40

Naphtalene

3.98

0.056822917

2.75

Phenanthrene

6.74

0.418906878

4.09

DDT

13.2

0.785100110

5.63

Values were calculated as the mean of 3 determinations. Using the capacity factor and the partition coefficient of the reference items, the following calibration curve was obtained:

log Koc = 3.1585 log k' + 2.8625 with R² = 0.9753

Table 5.4.1/2: Results for the test substance

Peak number

Retention time, min.

Area % (UV 210 nm)

Log Koc

1

2.55

2.38

1.50

2.55

2.36

1.50

2.55

2.36

1.50

2

3.65

8.74

2.81

3.65

8.74

2.81

3.65

8.73

2.81

3

4.42

88.88

3.30

4.43

88.90

3.31

4.42

88.91

3.30

Log Koc were calculated using the regression equation ( log Koc = 3.1585 log k' + 2.8625) with the corresponding retention time. The value of the log Koc is 3.30 for the most important peak corresponding to the test item. This result issued from the 3 determinations is in the guideline tolerance for repeatability (+/- 0.25 log units).

Validity criteria fulfilled:
yes
Conclusions:
Log Koc = 3.30 (3.30; 3.31 and 3.30 for the three determinations).
Executive summary:

The adsorption/desorption behaviour of the test substance on soil and sewage sludge was evaluated in a study performed in accordance with OECD testing guideline 121 and GLP requirements.

The test item is injected on a liquid chromatography system where a partition occurs between the stationary phase of the column and the eluent phase (methanol-water 55 -45 v/v). Chemicals are retained according to their adsorption coefficient. Therefore, a relation exists between the retention time and the adsorption coefficient of a chemical product. A correlation of log k' (capacity factor k') versus log Koc is plotted for the appropriate reference substances (Formamide, Acetanilide, Methyl benzoate, Triadimenol, Naphtalene, Phenanthrene and 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane). The regression equation is performed at regular intervals, so that account can be taken of possible changes in column performance. Three determinations are performed and the value retained for log Koc of the test item is the mean of the three values obtained.

During the analysis, the temperature was 30°C and the pH value was 7.5.

Using the capacity factor and the partition coefficient of the reference items, the following calibration curve was obtained:

Log Koc = 3.1585 log k' + 2.8625 with R² = 0.9753.

Results:

The test substance contains 3 components (from 1 to 3) based on the chromatograms obtained. The mass spectrometry profile confirmed that the UV peak n°3 corresponds to the test item.

Retention time for the peak n°3 (min) : 4.42; 4.43 and 4.42 minutes for the three determinations.

Area % (UV, 210 nm): between 88.88 to 88.91%.

Log Koc: 3.30; 3.31 and 3.30 for the three determinations (average log Koc = 3.30).

All validity criteria were fulfilled. However, as a non specific detector was used, no guarantee about respective proportions of components is be provided, nor attempt of identification of peaks.

 

Description of key information

OECD 121, GLP, key study, validity 2:
Log Koc = 3.30 at 30°C.

Key value for chemical safety assessment

Koc at 20 °C:
1 995.3

Additional information

One valid key study is available to assess the adsorption/desorption behaviour of the test substance on soil and sewage sludge. This study was performed in accordance with OECD testing guideline 121 and GLP requirements.

The test item is injected on a liquid chromatography system where a partition occurs between the stationary phase of the column and the eluent phase (methanol-water 55 -45 v/v). Chemicals are retained according to their adsorption coefficient. Therefore, a relation exists between the retention time and the adsorption coefficient of a chemical product. A correlation of log k' (capacity factor k') versus log Koc is plotted for the appropriate reference substances. During the analysis, the temperature was 30°C and the pH value was 7.5. Using the capacity factor and the partition coefficient of the reference items, the following calibration curve was obtained:

Log Koc = 3.1585 log k' + 2.8625 with R² = 0.9753.

The test substance contains 3 components (from 1 to 3) based on the chromatograms obtained. The mass spectrometry profile confirmed that the UV peak n°3 corresponds to the test item. The retention times for the peak n°3 were 4.42; 4.43 and 4.42 minutes for the three determinations, corresponding to area comprised between 88.88 to 88.91% (UV, 210 nm). Log Koc, calculated using the precedent regression equation with the corresponding retention times, were 3.30; 3.31 and 3.30 for the three determinations. The average log Koc was 3.30.

All validity criteria were fulfilled. However, as a non specific detector was used, no guarantee about respective proportions of components is be provided, nor attempt of identification of peaks.

 

[LogKoc: 3.3]